Publications by authors named "Johannes Linxweiler"

30 Publications

  • Page 1 of 1

Molecular imaging and biochemical response assessment after a single cycle of [Ac]Ac-PSMA-617/[Lu]Lu-PSMA-617 tandem therapy in mCRPC patients who have progressed on [Lu]Lu-PSMA-617 monotherapy.

Theranostics 2021 16;11(9):4050-4060. Epub 2021 Feb 16.

Department of Nuclear Medicine, Saarland University - Medical Center, Homburg, Germany.

Despite the promising results of prostate-specific membrane antigen (PSMA)-targeted Lu radioligand therapy in metastatic castration-resistant prostate carcinoma (mCRPC), some patients do not respond and other patients with initially good response develop resistance to this treatment. In this study, we investigated molecular imaging and biochemical responses after a single cycle of [Ac]Ac-PSMA-617/[Lu]Lu-PSMA-617 tandem therapy in patients who had progressed on [Lu]Lu-PSMA-617 monotherapy. Seventeen patients with mCRPC were included in a retrospective, monocenter study. Molecular imaging-based response was assessed by modified PERCIST criteria using the whole-body total lesion PSMA (TLP) and molecular tumour volume (MTV) derived from [Ga]Ga-PSMA-11 PET/CT. Biochemical response was evaluated according to PCWG3 criteria using the prostate-specific antigen (PSA) serum value. Concordance and correlation statistics as well as survival analyses were performed. Based on the molecular imaging-based response assessment, 5 (29.4%) patients showed partial remission and 7 (41.2%) had stable disease. The remaining 5 (29.4%) patients had further progression, four with an increase in TLP/MTV of >30% and one with stable TLP/MTV but appearance of new metastases. Based on the biochemical response assessment, 5 (29.4%), 8 (47.1%), and 4 (23.5%) patients showed partial remission, stable disease, and progressive disease, respectively. A comparison of the response assessment methods showed a concordance of 100% (17/17) between TLP and MTV and 70.6% (12/17) between TLP/MTV and PSA. Patients with partial remission, independently assessed by each method, had better overall survival (OS) than patients with either stable or progressive disease. The difference in OS was statistically significant for the molecular imaging response assessment (median OS not reached vs. 8.3 m, = 0.044), but not for the biochemical response assessment (median OS 18.1 m vs. 9.4 m, = 0.468). Based on both assessment methods, [Ac]Ac-PSMA-617/[Lu]Lu-PSMA-617 tandem therapy is an effective treatment for the highly challenging cohort of patients with mCRPC who have progressed on [Lu]Lu-PSMA-617 monotherapy. Molecular imaging response and biochemical PSA response were mostly concordant, though a considerable number of cases (29.4%) were discordant. Molecular imaging response reflecting the change in total viable tumour burden appears to be superior to PSA change in estimating survival outcome after tandem therapy.
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http://dx.doi.org/10.7150/thno.56211DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7977444PMC
February 2021

Robotic Salvage Lymph Node Dissection in Recurrent Prostate Cancer: Lessons Learned from 68 Cases and Implications for Future Clinical Management.

J Urol 2021 Feb 22:101097JU0000000000001697. Epub 2021 Feb 22.

Department of Urology, Saarland University, Homburg/Saar, Germany.

Purpose: Salvage lymph node dissection is a rescue treatment for patients with nodal recurrence after radical prostatectomy. Very limited data are available on robotic salvage lymph node dissection. Our purpose was to investigate perioperative and oncological outcomes of robotic salvage lymph node dissection in a large monocentric series.

Materials And Methods: Perioperative data, complications within 30 days after surgery and oncological outcomes as assessed by histology, prostate specific antigen changes, prostate specific antigen nadir after salvage lymph node dissection, and time to further therapy were analyzed. To identify predictive factors for oncological outcome, Kaplan-Meier and Cox-regression analyses were performed. For cases with a mismatch between preoperative positron emission tomography/computed tomography and the number of histologically positive lymph nodes, prostate specific membrane antigen immunohistochemistry was performed on removed lymph nodes.

Results: A total of 68 patients underwent robotic salvage lymph node dissection with a median operation time of 126 minutes, a blood loss of 50 ml, and a length of stay of 4 days. No major complications (>Clavien 3) occurred. Median followup was 12.1 months. Median time to further therapy was 12.4 months, 37% of patients experienced complete biochemical response (prostate specific antigen <0.2 ng/ml) and 11% reached an undetectable prostate specific antigen, which was maintained for >1 year in 3 cases. Lower preoperative prostate specific antigen, longer time between radical prostatectomy and salvage lymph node dissection, preoperative prostate specific membrane antigen positron emission tomography/computed tomography and complete biochemical response after salvage lymph node dissection were significant predictors of longer therapy-free survival (all p <0.005). Prostate specific membrane antigen immunohistochemistry revealed that prostate specific membrane antigen positron emission tomography/computed tomography tends to miss small lymph node metastases <5 mm.

Conclusions: Robotic salvage lymph node dissection is a feasible approach with low perioperative morbidity and delays further systemic therapy in most patients. Prostate specific membrane antigen positron emission tomography/computed tomography detection is mostly limited to tumor foci >5 mm.
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http://dx.doi.org/10.1097/JU.0000000000001697DOI Listing
February 2021

Can local treatment prolong the sensitivity of metastatic prostate cancer to androgen deprivation or even prevent castration resistance?

World J Urol 2021 Jan 27. Epub 2021 Jan 27.

Department of Urology and Pediatric Urology, Saarland University, Homburg/Saar, Germany.

Purpose: A number of observational clinical studies suggest that prior primary tumor treatment favorably influences the course of metastatic prostate cancer (PCa), but its mechanisms of action are still speculative. Here, we describe the long-lasting sensitivity to various forms of androgen deprivation in patients after radical prostatectomy (RP) for locally advanced PCa as one potential mechanism.

Methods: A consecutive series of 115 radical prostatectomies after inductive therapy for T4 prostate cancer was re-analyzed, and long-term survival, as well as recurrence patterns and responses to different forms of hormonal manipulation, were assessed.

Results: The estimated biochemical response-free, PCa-specific, and overall survival rates after 200 months were 20%, 65%, and 47% with a median overall survival of 156 months. The majority of patients, although not cured of locally advanced PCa (84/115), showed long-term survival after RP. PCa-specific and overall survival rates of these 84 patients with biochemical recurrence were 61% and 44% at 150 months. Long-term sensitivity to ADT was found to be the main reason for the favorable tumor-specific survival in spite of biochemical recurrence.

Conclusions: Sensitivity to primary or secondary hormonal manipulation was the main reason for the long-term survival of patients who had not been cured by surgery only. The results suggest that treatment of the primary tumor-bearing prostate delays castration-resistant PCa and enhances the effect of hormonal therapies in a previously unknown manner. The underlying cellular and molecular mechanisms need to be explored in more detailed analyses, which could profoundly impact treatment concepts of locally advanced and metastatic PCa.
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http://dx.doi.org/10.1007/s00345-020-03568-3DOI Listing
January 2021

[When a urological emergency indicates an internal medical crisis : Priapism as the first clinical manifestation of leukemia].

Urologe A 2021 Jan;60(1):67-70

Klinik für Urologie und Kinderurologie, Universität des Saarlandes, Kirrberger Straße, Gebäude 6, 66424, Homburg/Saar, Deutschland.

Priapism as a sign of a severe hematological disease is a rare event, which has to be considered as both a urological and a hematological emergency that requires immediate treatment. This article describes a clinical case of priapism as the first clinical manifestation of a hitherto undiagnosed chronic myeloid leukemia (CML) and discusses the results of a literature review on this topic.
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http://dx.doi.org/10.1007/s00120-020-01326-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7819961PMC
January 2021

Open versus robot-assisted partial nephrectomy: A longitudinal comparison of 880 patients over 10 years.

Int J Med Robot 2021 Feb 21;17(1):1-8. Epub 2020 Sep 21.

Department of Urology and Pediatric Urology, Saarland University, Homburg/Saar, Germany.

Background: Most comparisons between robot-assisted partial nephrectomy (RAPN) and open partial nephrectomy (OPN) indicate the superiority of RAPN, but the learning curve is often not considered.

Methods: All consecutive partial nephrectomies from the very first RAPN at a single tertiary referral centre (n = 818, 500 RAPN vs. 313 OPN) were retrospectively analyzed. Complications, success rates and surgical outcomes were compared. Inequalities between cohorts and the inherent learning curve were controlled by subgroup comparisons, regression analyses, and propensity score matching.

Results: Overall, RAPN had fewer complications, less blood loss, and shorter length of stay. However, an inherent learning curve caused higher complications for the first 4 years. Thereafter, perioperative outcomes clearly favoured RAPN, even for more complex tumours.

Conclusions: In one of the largest monocentric cohorts over more than 10 years, RAPN was found to be superior to OPN. However, not all advantages of RAPN are immediate because a learning curve must be passed.
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http://dx.doi.org/10.1002/rcs.2167DOI Listing
February 2021

Cancer-associated fibroblasts stimulate primary tumor growth and metastatic spread in an orthotopic prostate cancer xenograft model.

Sci Rep 2020 07 28;10(1):12575. Epub 2020 Jul 28.

Department of Urology and Pediatric Urology, Saarland University, Kirrberger Straße 100, Gebäude 6, 66424, Homburg/Saar, Germany.

The unique microenvironment of the prostate plays a crucial role in the development and progression of prostate cancer (PCa). We examined the effects of cancer-associated fibroblasts (CAFs) on PCa progression using patient-derived fibroblast primary cultures in a representative orthotopic xenograft model. Primary cultures of CAFs, non-cancer-associated fibroblasts (NCAFs) and benign prostate hyperplasia-associated fibroblasts (BPHFs) were generated from patient-derived tissue specimens. These fibroblasts were coinjected together with cancer cells (LuCaP136 spheroids or LNCaP cells) in orthotopic PCa xenografts to investigate their effects on local and systemic tumor progression. Primary tumor growth as well as metastatic spread to lymph nodes and lungs were significantly stimulated by CAF coinjection in LuCaP136 xenografts. When NCAFs or BPHFs were coinjected, tumor progression was similar to injection of tumor cells alone. In LNCaP xenografts, all three fibroblast types significantly stimulated primary tumor progression compared to injection of LNCaP cells alone. CAF coinjection further increased the frequency of lymph node and lung metastases. This is the first study using an orthotopic spheroid culture xenograft model to demonstrate a stimulatory effect of patient-derived CAFs on PCa progression. The established experimental setup will provide a valuable tool to further unravel the interacting mechanisms between PCa cells and their microenvironment.
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http://dx.doi.org/10.1038/s41598-020-69424-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7387494PMC
July 2020

Current Role of Multiparametric MRI and MRI Targeted Biopsies for Prostate Cancer Diagnosis in Germany: A Nationwide Survey.

Urol Int 2020 8;104(9-10):731-740. Epub 2020 Jul 8.

Department of Urology and Pediatric Urology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.

Introduction: Multiparametric MRI (mpMRI) and MRI targeted biopsies (MRtb) are a new standard in prostate cancer (PCa) screening and diagnosis. Guidelines already include this approach for patients at risk. We aimed to gather information from German urologists about their knowledge, routine use, and attitude toward mpMRI and consecutive biopsy methods.

Materials And Methods: An anonymous online questionnaire was sent via Survey Monkey to the members of the German Society of Urology (DGU). Statistical analyses were performed using SPSS version 25.0.

Results: 496 members with a median age of 48.6 years (±11.7) participated in the survey. The majority rated mpMRI of the prostate as a very useful diagnostic tool (72.7%). MRtb of the prostate was considered as very advantageous (71.5%). MpMRI was used by 95.9%, and 83.2% also recommended MRtb predominantly in clinical institutions. For targeted biopsy, MRI-ultrasound fusion biopsy was clearly favored (75.8%). MpMRI was mostly used in patients with previously negative biopsy (90.9%) and in patients under active surveillance (60.9%). Arguments against the use of prostate mpMRI are costs (84.9%) and/or lack of sufficient radiological infrastructure (17.4%).

Conclusion: Our data illustrate the meanwhile high acceptance and clinical use of the prostate mpMRI and MRtb in Germany.
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http://dx.doi.org/10.1159/000508755DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7592851PMC
July 2020

Robot-Assisted versus Laparoscopic Donor Nephrectomy: A Comparison of 250 Cases.

J Clin Med 2020 May 26;9(6). Epub 2020 May 26.

Department of Urology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humbold-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, 10117 Berlin, Germany.

Living kidney donation is the best treatment for end-stage renal disease, however, the best surgical approach for minimally-invasive donor nephrectomy (DN) is still a matter of debate. This bi-centric study aimed to retrospectively compare perioperative outcomes and postoperative kidney function after 257 transperitoneal DNs including 52 robot-assisted (RDN) and 205 laparoscopic DNs (LDN). As primary outcomes, the intraoperative (operating time, warm ischemia time (WIT), major complications) and postoperative (length of stay, complications) results were compared. As secondary outcomes, postoperative kidney and graft function were analyzed including delayed graft function (DGF) rates, and the impact of the surgical approach was assessed. Overall, the type of minimally-invasive donor nephrectomy (RDN vs. LDN) did not affect primary outcomes, especially not operating time and WIT; and major complication and DGF rates were low in both groups. A history of smoking and preoperative kidney function, but not the surgical approach, were predictive for postoperative serum creatinine of the donor and recipient. To conclude, RDN and LDN have equivalent perioperative results in experienced centers. For this reason, not the surgical approach, but rather the graft- (preoperative kidney function) and patient-specific (history of smoking) aspects impacted postoperative kidney function.
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http://dx.doi.org/10.3390/jcm9061610DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7355615PMC
May 2020

Neuron-specific enolase has potential value as a biomarker for [F]FDG/[Ga]Ga-PSMA-11 PET mismatch findings in advanced mCRPC patients.

EJNMMI Res 2020 May 24;10(1):52. Epub 2020 May 24.

Department of Nuclear Medicine, Saarland University-Medical Center, Kirrberger Str. 100, Geb. 50, 66421, Homburg, Germany.

Background: PSMA-targeted radioligand therapy (PSMA-RLT) yielded impressive results in the metastasized castration-resistant prostate carcinoma (mCRPC) setting. High expression of PSMA is essential for successful PSMA-RLT. However, some patients develop [F]FDG-avid lesions with low or no PSMA expression ([F]FDG/[Ga]Ga-PSMA-11 mismatch findings on PET/CT) in the course of treatment. Those lesions are not affected by PSMA-RLT and a change in therapy management is needed. To enable early mismatch detection, possible blood parameters as indicators for the occurrence of [F]FDG/[Ga]Ga-PSMA-11 mismatch findings on PET/CT were evaluated.

Methods: Retrospective study of N = 66 advanced mCRPC patients with dual [Ga]Ga-PSMA-11 and [F]FDG PET/CT imaging within 4 weeks, who were referred for or received [Lu]Lu-PSMA-617 radioligand therapy. Prostate-specific antigen (PSA), neuron-specific enolase (NSE), gamma-glutamyltransferase (GGT), and alkaline phosphatase (ALP) were tested as indicators for the occurrence of [F]FDG/[Ga]Ga-PSMA-11 mismatch findings. Additional to absolute values, relative changes (ΔPSA, ΔNSE, ΔGGT, ΔALP) over a period of 4 ± 1 weeks prior to [F]FDG PET/CT were analyzed.

Results: In total, 41/66 (62%) patients revealed at least one [F]FDG/[Ga]Ga-PSMA-11 mismatch finding on PET/CT. These mismatch findings were detected in 13/41 (32%) patients by screening for and in 28/41 (68%) patients during PSMA-RLT. NSE serum level (55.4 ± 44.6 μg/l vs. 18.5 ± 8 μg/l, p < 0.001) and ΔNSE (93.8 ± 124.5% vs. 2.9 ± 39.5%, p < 0.001) were significantly higher in the mismatch group than in the non-mismatch group. No significant differences were found for serum PSA (p = 0.424), ΔPSA (p = 0.417), serum ALP (p = 0.937), ΔALP (p = 0.611), serum GGT (p = 0.773), and ΔGGT (p = 0.971). For NSE and ΔNSE, the maximum value of the Youden index in ROC analysis was at a cut-off level of 26.8 μg/l (sensitivity 78%, specificity 96%) and at + 13.9% (sensitivity 84%, specificity 75%), respectively. An introduced scoring system of both parameters achieved a sensitivity of 90% and a specificity of 88% for the occurrence of [F]FDG/[Ga]Ga-PSMA-11 mismatch.

Conclusion: We observed a significantly higher absolute serum concentration and a higher relative increase of NSE in advanced mCRPC patients with [F]FDG-avid and insufficient PSMA expressing metastases ([F]FDG/[Ga]Ga-PSMA-11 mismatch findings on PET/CT) in our cohort. NSE might be used as a potential laboratory indicator for [F]FDG/[Ga]Ga-PSMA-11 mismatch findings, if this observation is confirmed in future, ideally prospective, studies in larger patient cohorts.
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http://dx.doi.org/10.1186/s13550-020-00640-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7246282PMC
May 2020

New insights in the paradigm of upregulation of tumoral PSMA expression by androgen receptor blockade: Enzalutamide induces PSMA upregulation in castration-resistant prostate cancer even in patients having previously progressed on enzalutamide.

Eur J Nucl Med Mol Imaging 2020 03 3;47(3):687-694. Epub 2020 Jan 3.

Department of Nuclear Medicine, Saarland University, Kirrberger Str. 100, Geb. 50, 66421, Homburg, Germany.

Purpose: There is preliminary evidence for prostate-specific membrane antigen (PSMA) upregulation effects of androgen receptor blockade in prostate cancer. In an attempt to find the best condition for PSMA radioligand therapy in metastatic castration-resistant prostate cancer (mCRPC) patients, we evaluated the effect of oral enzalutamide in patients, predominantly having previously progressed on enzalutamide treatment.

Methods: Ten patients with advanced mCRPC scheduled for PSMA radioligand therapy were examined with Ga-PSMA-11 PET/CT before and after a mean of 11.8 days of enzalutamide 160 mg/day. Imaging results were compared using total PSMA tumor burden quantification. We assessed whole-body total lesion PSMA (TLP), defined as SUV × tumor volume and calculated TLP-to-liver ratio (TLP-LR), TLP-to-parotid gland ratio (TLP-PR), and TLP-to-kidney ratio (TLP-KR).

Results: The mean (median) increase of TLP-LR, TLP-PR, and TLP-KR in the cohort was 49.3% (38.8%), 45.1% (23.5%), and 54.9% (37.6%), respectively. These increases were statistically significant (p = 0.002, p = 0.014, and p = 0.014), while PSA values did not change significantly (p = 0.846). Seven of the 10 patients had previously undergone enzalutamide treatment with eventual progression, formally classified as treatment failure. No side effects were noted in the short term.

Conclusions: Our results suggest that enzalutamide could be considered as a PSMA radioligand treatment enhancing primer medication, which may increase PSMA expression by a dimension of 50% in mCRPC. The effect was shown even in patients having previously failed enzalutamide treatment for arrest of progression in the mCRPC setting. Our observation deserves evaluation in a prospective setting.
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http://dx.doi.org/10.1007/s00259-019-04674-0DOI Listing
March 2020

Publisher Correction: Extracellular vesicles in urological malignancies: an update.

Nat Rev Urol 2020 01;17(1):62

Department of Urology and Pediatric Urology, Saarland University, Homburg/Saar, Germany.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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http://dx.doi.org/10.1038/s41585-019-0279-yDOI Listing
January 2020

Extracellular vesicles in urological malignancies: an update.

Nat Rev Urol 2020 01 11;17(1):11-27. Epub 2019 Dec 11.

Department of Urology and Pediatric Urology, Saarland University, Homburg/Saar, Germany.

Extracellular vesicles (EVs) have an essential functional role in local tumour progression, metastatic spread and the emergence of drug resistance in bladder, kidney and prostate cancer. Thus, EVs could be diagnostic, prognostic and predictive biomarkers for these malignancies. Virtually all biomolecules (including DNA, mRNA, microRNA, long non-coding RNA, proteins and lipids) packaged into EVs have been tested as biomarkers in blood and urine samples. The results are very heterogeneous, but promising biomarker candidates have been identified. Differing methods of EV isolation, characterization and analysis of their content have been used owing to a lack of international consensus; hence, comparing study results is challenging. Furthermore, validation of potential biomarkers in independent cohorts or prospective trials has rarely been performed. Future efforts to establish EV-derived biomarkers need to adequately address these points. In addition, emerging technologies such as mass spectroscopy and chip-based approaches can identify surface markers specific for cancer-associated EVs and will enable specific separation from blood and urine EVs, which probably will improve their performance as biomarkers. Moreover, EVs could be harnessed as therapeutic drug delivery vehicles for precise and effective anticancer therapy.
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http://dx.doi.org/10.1038/s41585-019-0261-8DOI Listing
January 2020

Non-coding RNAs as biomarkers in liquid biopsies with a special emphasis on extracellular vesicles in urological malignancies.

Expert Rev Mol Diagn 2020 02 18;20(2):151-167. Epub 2019 Sep 18.

Department of Urology and Pediatric Urology, Saarland University, Homburg, Germany.

: Non-coding RNAs (ncRNAs) are important regulators of cellular signaling in tumor-related processes. They can not only be detected in tumor tissues, but also in body fluids. ncRNAs are released into circulation as cell-free RNAs in at least two ways: bound to proteins like Ago2 or packed in extracellular vesicles (EV). Therefore, they have a great potential to serve as biomarkers in liquid biopsies. This review gives an overview of the current knowledge concerning ncRNAs and EVs as putative liquid biomarkers in urological tumor diseases.: Literature was searched for ncRNAs including microRNA, long non-coding RNA, small interfering RNA, small nuclear RNA, small nucleolar RNA and PIWI-interacting RNA in blood (serum, plasma) and urine samples from urological tumor (urothelial, kidney, prostate, testicular germ cell, penile cancer) patients.: The data demonstrate an important potential of circulating non-coding RNAs as biomarkers in liquid biopsies for diagnosis and follow-up of patients with urological tumors. To translate these markers into clinical practice, independent and prospective validation, standardization of isolation and quantification techniques are inevitable. Another task is the development of predictive ncRNA biomarkers to overcome problems associated with tumor heterogeneity and to select patients individually for systemic therapies.
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http://dx.doi.org/10.1080/14737159.2019.1665998DOI Listing
February 2020

Patient-derived, three-dimensional spheroid cultures provide a versatile translational model for the study of organ-confined prostate cancer.

J Cancer Res Clin Oncol 2019 Mar 24;145(3):551-559. Epub 2018 Nov 24.

Department of Urology, Saarland University, Homburg, Saar, Germany.

Purpose: To generate and characterize 3D spheroid suspension cultures from radical prostatectomy (RP) specimens as a versatile model system for organ-confined prostate cancer (PCa).

Methods: Cancerous tissue samples from RP specimens were excised by a uropathologist. Preparation of 3D spheroids was done by mechanical disintegration and limited enzymatic digestion followed by serial filtration through 100 μm- and 40 μm-cell strainers. Thereafter, spheroids were cultured in a modified stem cell medium and characterized by a live/dead assay, whole-spheroid immunohistochemistry (IHC; CK5, CK8, AMACR, PSA, Ki67, AR, αSMA, Vimentin, E-Cadherin) and PSA-measurements in culture medium. Furthermore, their response to pharmaceutical treatment with docetaxel, bicalutamide, enzalutamide and abiraterone was tested.

Results: 173 RP cases were included. The median preoperative PSA-level was 16.12 ng/ml [range 0.99;345], the median Gleason score was 7b [6;10]. 64 cases were excluded due to low tumor content in frozen sections (43) or to insufficient spheroid formation (21). In the remaining 109 cases, spheroids formed successfully and stayed viable for up to several months. IHC analysis revealed AR-, CK8-, and AMACR-positivity in nearly all cases, while CK5-positive cells were detectable only occasionally as were α-SMA and Vimentin. E-Cadherin was positive in most cases. Furthermore, spheroids proved to be amenable to cryopreservation. While abiraterone had no effect and docetaxel only a moderate effect, spheroid viability was markedly reduced upon bicalutamide and enzalutamide treatment.

Conclusions: Multicellular 3D spheroids can be generated from patient-derived RP tissue samples and serve as an innovative in vitro model of organ-confined PCa.
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http://dx.doi.org/10.1007/s00432-018-2803-5DOI Listing
March 2019

Two Years of Gynecomastia Caused by Leydig Cell Tumor.

Case Rep Urol 2018 19;2018:7202560. Epub 2018 Jul 19.

Department of Urology and Pediatric Urology, Saarland University, Homburg/Saar, Germany.

Gynecomastia is a common incidental finding in males that can be caused by various benign or malignant diseases. In rare cases, it results from Leydig cell tumors, a rare entity accounting for 3% of all testicular neoplasms. Some of them are hormonally active but seldom cause symptomatic endocrine disturbance. Here we report on a 32-year-old male presenting with gynecomastia which he had already been suffering from for two years. Although he had been seen by three other specialists, including a urologist, none of them found the small mass in the upper pole of his right testis. We decided to perform testis-sparing surgery which confirmed the diagnosis of a hormonally active Leydig cell tumor. During follow-up, hormonal status normalized, and gynecomastia began to resolve.
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http://dx.doi.org/10.1155/2018/7202560DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6077527PMC
July 2018

Robotic salvage lymph node dissection for nodal-only recurrences after radical prostatectomy: Perioperative and early oncological outcomes.

Surg Oncol 2018 Jun 24;27(2):138-145. Epub 2018 Feb 24.

Department of Urology, Saarland University, Kirrberger Straße 100, Building 6, Homburg/Saar, Germany. Electronic address:

Background: Salvage lymph node dissection (sLND) - performed open or minimally-invasive - is a treatment modality that can be offered to patients with nodal recurrence after radical prostatectomy (RP), especially in times where modern imaging methods like choline- or PSMA-PET/CT are available. Yet, there are only very limited data on the safety and oncological effectiveness of robotic sLND.

Methods: We retrospectively identified patients who underwent robotic sLND at our institution between 2013 and 2017 for nodal recurrence after RP, which had been diagnosed either by F-choline- or Ga-PSMA-PET/CT. We analyzed perioperative data and early oncological outcomes with a focus on the comparison of patients with preoperative choline- vs. those with preoperative PSMA-PET/CT.

Results: We identified 36 patients who underwent robotic sLND at a median time of 45.3 months [range 3.1;228.6] after RP, with nodal recurrences detected in 25 patients by PSMA- and in 11 by choline-PET/CT. Median preoperative PSA, operation time and blood loss were 1.98 ng/ml [range 0.09;35.15], 129.5 min [range 65;202] and 50 ml [range 0;400], respectively. No high-grade complications occurred. A median number of 6.5 [range 1;25] lymph nodes were removed with a median of 1 [range 0;9] tumor-occupied node. None of the patients received any adjuvant treatment. Median postoperative PSA-change was -57% [range -100; +58] in the PSMA- and +10% [range -91; +95] in the choline-group (p = 0.015). 44% of patients in the PSMA- and 18% of patients in the choline-group experienced complete biochemical response (cBCR; PSA <0.2 ng/ml). Median time from sLND to the initiation of further therapy was 12 months [range 2;21.5] in the PSMA-group and 4.7 months [range 2.2;18.9] in the choline-group (p = 0.001).

Conclusions: This is the hitherto largest series on robotic sLND for nodal recurrence after RP. Robotic sLND is a feasible therapeutic option with low morbidity, which can at least delay the initiation of further therapy - in some patients up to several years. However, the extend of sLND has to be standardized and randomized trials are needed to finally define the oncological effectiveness of this approach.
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http://dx.doi.org/10.1016/j.suronc.2018.02.010DOI Listing
June 2018

Radical prostatectomy in T4 prostate cancer after inductive androgen deprivation: results of a single-institution series with long-term follow-up.

BJU Int 2019 01 7;123(1):58-64. Epub 2018 Jun 7.

Department of Urology and Pediatric Urology, Saarland University, Homburg/Saar, Germany.

Objectives: To determine the outcomes of complete surgical resection of T4 prostate cancer after inductive androgen-deprivation therapy (ADT), as inductive ADT and subsequent radical prostatectomy (RP) is not recommended by any guideline yet.

Patients And Methods: A monocentric RP database was queried for patients initially diagnosed with T4 prostate cancer, considered primarily as inoperable because of a fixed mass defined by rectal examination in combination with high PSA level and/or large foci of biopsy confirmed undifferentiated prostate cancer. Treatment consisted of primary ADT until PSA nadir with consecutive RP. Patients underwent retropubic RP (RRP) or robot-assisted laparoscopic RP (RALP) after inductive ADT until achievement of the PSA nadir, which is in general reached after 6-7 months. The intraoperative course and complications were analysed. Finally, Kaplan-Meier estimates were calculated for overall survival (OS) and prostate cancer-specific survival (PCSS).

Results: We retrospectively identified 116 patients treated between 2000 and 2014. At diagnosis, the median (range) PSA level was 37.6 (2.44-284) ng/mL. The preoperative median (range) PSA after inductive ADT was 0.73 (0.01-34) ng/mL. Thereafter, patients underwent RRP or, since 2006, RALP. The median (95% confidence interval) OS was 156 (118.9-193.1) months. The PCSS at 150 months was 82%.

Conclusions: Surgical therapy of primarily inoperable prostate cancer is feasible and safe after inductive ADT. The OS of this cohort seems comparable with results described for patients with primary operable high-risk prostate cancer.
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http://dx.doi.org/10.1111/bju.14393DOI Listing
January 2019

A novel mouse model of human prostate cancer to study intraprostatic tumor growth and the development of lymph node metastases.

Prostate 2018 06 24;78(9):664-675. Epub 2018 Mar 24.

Department of Urology, Saarland University, Homburg/Saar, Germany.

Background: In this study, we aimed to establish a versatile in vivo model of prostate cancer, which adequately mimics intraprostatic tumor growth, and the natural routes of metastatic spread. In addition, we analyzed the capability of high-resolution ultrasonography (hrUS), in vivo micro-CT (μCT), and 9.4T MRI to monitor tumor growth and the development of lymph node metastases.

Methods: A total of 5 × 10 VCaP cells or 5 × 10 cells of LuCaP136- or LuCaP147 spheroids were injected into the prostate of male CB17-SCID mice (n = 8 for each cell type). During 12 weeks of follow-up, orthotopic tumor growth, and metastatic spread were monitored by repetitive serum-PSA measurements and imaging studies including hrUS, μCT, and 9.4T MRI. At autopsy, primary tumors and metastases were harvested and examined by histology and immunohistochemistry (CK5, CK8, AMACR, AR, Ki67, ERG, and PSA). From imaging results and PSA-measurements, tumor volume doubling time, tumor-specific growth rate, and PSA-density were calculated.

Results: All 24 mice developed orthotopic tumors. The tumor growth could be reliably monitored by a combination of hrUS, μCT, MRI, and serum-PSA measurements. In most animals, lymph node metastases could be detected after 12 weeks, which could also be well visualized by hrUS, and MRI. Immunohistochemistry showed positive signals for CK8, AMACR, and AR in all xenograft types. CK5 was negative in VCaP- and focally positive in LuCaP136- and LuCaP147-xenografts. ERG was positive in VCaP- and negative in LuCaP136- and LuCaP147-xenografts. Tumor volume doubling times and tumor-specific growth rates were 21.2 days and 3.9 %/day for VCaP-, 27.6 days and 3.1 %/day for LuCaP136- and 16.2 days and 4.5 %/day for LuCaP147-xenografts, respectively. PSA-densities were 433.9 ng/mL per milliliter tumor for VCaP-, 6.5 ng/mL per milliliter tumor for LuCaP136-, and 11.2 ng/mL per milliliter tumor for LuCaP147-xenografts.

Conclusions: By using different monolayer and 3D spheroid cell cultures in an orthotopic xenograft model, we established an innovative, versatile in vivo model of prostate cancer, which enables the study of both intraprostatic tumor growth as well as metastatic spread to regional lymph nodes. HrUS and MRI are feasible tools to monitor tumor growth and the development of lymph node metastases while these cannot be visualized by μCT.
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http://dx.doi.org/10.1002/pros.23508DOI Listing
June 2018

Combinational chromosomal aneuploidies and HPV status for prediction of head and neck squamous cell carcinoma prognosis in biopsies and cytological preparations.

J Cancer Res Clin Oncol 2018 Jun 20;144(6):1129-1141. Epub 2018 Mar 20.

Department of Otorhinolaryngology, Saarland University Medical Center, Kirrberger Street 100, 66421, Homburg (Saar), Germany.

Purpose: Head and neck squamous cell carcinoma (HNSCC) is one of the most common human cancer types with a very poor prognosis despite improvements in therapeutic modalities. The major known risk factors are tobacco use and alcohol consumption or infection with high-risk human papilloma viruses (HPV), especially in oropharyngeal tumors. The current management based on the assessment of a variety of clinical and pathological parameters does not sufficiently predict outcome.

Methods: Chromosomal alterations detected in HNSCCs were characterized by metaphase comparative genomic hybridization (CGH) and correlated with clinical parameters as well as survival time. Candidate regions were validated by quantitative polymerase chain reaction, fluorescence-in situ-hybridization (FISH) on dapped tumor tissue and liquid-based cytological smear preparations. In addition, HPV status was determined by polymerase chain reaction and simultaneous immunocytochemical p16-Ki67 staining.

Results: The most frequent DNA copy number gains were observed on chromosome arms 3q, 8q, 5p, 7q, 12p, and 12q. DNA copy number decreases occurred most frequently at 3p, 17p, 4q, and 5q. FISH analysis verified in part the observed alterations by CGH on dapped tissues and was especially able to detect the most frequent DNA copy changes in cytological specimens.

Conclusion: The combination of HPV status and prognostic copy number alteration detected by FISH in biopsies or cytological specimens may be an applicable protocol for screening head and neck cancer patients prior to therapy.
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http://dx.doi.org/10.1007/s00432-018-2629-1DOI Listing
June 2018

Kidney autotransplantation after nephrectomy and work bench surgery as an ultimate approach to nephron-sparing surgery.

World J Surg Oncol 2018 Feb 20;16(1):35. Epub 2018 Feb 20.

Department of Urology and Pediatric Urology, University of Saarland, Kirrbergerstr. 6, 66421, Homburg/Saar, Germany.

Background: Kidney autotransplantation (KAT) is the ultimate approach for nephron-sparing surgery. It is a rarely used method in renal tumor surgery today as minimal invasive and open techniques for nephron-sparing surgery improve constantly. In this publication, the complication rate and the long-term functional and oncological outcome at a single center are analyzed.

Methods: A prospectively constructed database of patients with renal tumors who underwent renal surgery was retrospectively analyzed to identify patients with KAT and describe surgical and oncological outcomes and to obtain long-term follow-up. Data collection included detailed surgical technique, complications (Clavian-Dindo), and hospital stay, as well as functional and oncological outcome and long-term follow-up.

Results: Between 1976 and 2013, 12 patients (median age 50.5 years) underwent KAT for highly complex renal masses: in five cases for complex renal cell carcinoma (RCC), five cases for complex upper urinary tract carcinoma (UTUC), one case for a renal metastasis, and one case for nephroblastoma. The nephrectomy or nephron-ureterectomy was performed open via a flank or transabdominal. The median surgical time was 360 min (range 270-490 min). Intraoperatively, six cases required blood transfusions (50%). Six patients (50%) developed significant postoperative complications (Clavian-Dindo > 2). In two patients, intermittent hemodialysis for delayed graft function (16.6%) was needed, and in six cases (50%), additional blood transfusions postoperatively were necessary. At discharge from hospital, all patients had functioning grafts. The median hospital stay was 29.5 days (range 18-35). At follow-up (median follow-up of 83.5 ± 40.7 months), six patients had died (50%)-all with functioning grafts (free from hemodialysis). In five cases, recurrence of primary tumor or metastatic disease was recorded. In four cases, the recurrent carcinoma could be resected; in detail, UTUC in three cases and one partial nephrectomy of the autotransplanted kidney was performed. One patient suffered from bone and lung metastasis. Two patients died finally tumor-related. Five patients (41.6%) are presently alive, without evidence of tumor relapse. One patient developed terminal renal failure requiring hemodialysis 105 months after autotransplantation. One additional patient was lost to follow-up; after 69 months, this patient had a functioning kidney and no evidence of disease-recurrence at the last follow-up. A cumulative number of 1424 months without hemodialysis was gained for these 12 patients. In the literature to date, most KAT are performed in benign disease, with minor but frequent complication. Here, we report the largest series of KAT for malignant kidney tumors. The complication rates are similar, compared to the recently reported series for benign indications with an improved graft survival rate. Since KAT requires a complex and challenging surgical approach, it should be performed by experienced kidney transplant surgeons.

Conclusion: In very complex cases involving renal tumors and multi-morbidity, patients should be counseled well before KAT is considered. At the same time, KAT should not be abandoned in these very rare cases, especially when a nephron-sparing approach is otherwise not feasible. KAT can maintain renal function and quality of life and extend expectancy of life.
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http://dx.doi.org/10.1186/s12957-018-1338-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5819675PMC
February 2018

Experimental imaging in orthotopic renal cell carcinoma xenograft models: comparative evaluation of high-resolution 3D ultrasonography, in-vivo micro-CT and 9.4T MRI.

Sci Rep 2017 10 27;7(1):14249. Epub 2017 Oct 27.

Department of Urology, Saarland University, Homburg/Saar, Germany.

In this study, we aimed to comparatively evaluate high-resolution 3D ultrasonography (hrUS), in-vivo micro-CT (μCT) and 9.4T MRI for the monitoring of tumor growth in an orthotopic renal cell carcinoma (RCC) xenograft model since there is a lack of validated, non-invasive imaging tools for this purpose. 1 × 10 Caki-2 RCC cells were implanted under the renal capsule of 16 immunodeficient mice. Local and systemic tumor growth were monitored by regular hrUS, μCT and MRI examinations. Cells engrafted in all mice and gave rise to exponentially growing, solid tumors. All imaging techniques allowed to detect orthotopic tumors and to precisely calculate their volumes. While tumors appeared homogenously radiolucent in μCT, hrUS and MRI allowed for a better visualization of intratumoral structures and surrounding soft tissue. Examination time was the shortest for hrUS, followed by μCT and MRI. Tumor volumes determined by hrUS, μCT and MRI showed a very good correlation with each other and with caliper measurements at autopsy. 10 animals developed pulmonary metastases being well detectable by μCT and MRI. In conclusion, each technique has specific strengths and weaknesses, so the one(s) best suitable for a specific experiment may be chosen individually.
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http://dx.doi.org/10.1038/s41598-017-14759-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5660163PMC
October 2017

Initial evidence for Sec62 as a prognostic marker in advanced head and neck squamous cell carcinoma.

Oncol Lett 2016 Mar 20;11(3):1661-1670. Epub 2016 Jan 20.

Department of Otorhinolaryngology, Saarland University and Clinic of Urology and Pediatric Urology, Saarland University Medical Center, Homburg D-66421, Germany.

Head and neck squamous cell carcinoma (HNSCC) is a malignancy with an increasing incidence. To aid with the selection of the most appropriate therapy, biomarkers have become a specific research focus. Sec62 is involved in endoplasmic reticulum stress tolerance and cell migration, and has been identified as a novel prognostic marker for non-small cell lung cancer. In addition, Sec62 may be a promising candidate in HNSCC. Pretreatment biopsies of 35 patients with locally advanced HNSCC, who were treated with definitive chemoradiation therapy without prior surgery, were examined for the expression of Sec62 protein, as well as the expression of epidermal growth factor receptor (EGFR), p16 and survivin proteins. Immunohistological results were correlated with patient overall survival (OS) and progression-free survival (PFS) times. In the present patient cohort, 12/35 cases (34%) demonstrated strong and 8/35 cases (23%) moderate Sec62 staining intensity. Additionally, in 11/35 cases (31%), weak staining was observed, and only 4/35 cases (11%) were Sec62-negative. Notably, a high Sec62 protein level was associated with a significantly poorer OS and PFS (P=0.020 and P=0.028, respectively). Furthermore, higher nuclear survivin expression showed a weak trend for poorer OS rate (P=0.079), whilst neither cytoplasmic survivin, EGFR nor p16 influenced OS or PFS significantly. The present study indicated that Sec62 is a promising prognostic marker for HNSCC. Increased Sec62 protein expression may indicate a poorer prognosis in advanced HNSCC. As the present study was focused on patients treated by chemoradiation therapy, further studies with larger patient cohorts and alternative treatment approaches are required in order to define the prognostic value of Sec62 in HNSCC.
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http://dx.doi.org/10.3892/ol.2016.4135DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4774472PMC
March 2016

Spheroid culture of LuCaP 136 patient-derived xenograft enables versatile preclinical models of prostate cancer.

Clin Exp Metastasis 2016 Apr 12;33(4):325-37. Epub 2016 Feb 12.

Department of Urology, Stanford University School of Medicine, Stanford, CA, 94305, USA.

LuCaP serially transplantable patient-derived xenografts (PDXs) are valuable preclinical models of locally advanced or metastatic prostate cancer. Using spheroid culture methodology, we recently established cell lines from several LuCaP PDXs. Here, we characterized in depth the features of xenografts derived from LuCaP 136 spheroid cultures and found faithful retention of the phenotype of the original PDX. In vitro culture enabled luciferase transfection into LuCaP 136 spheroids, facilitating in vivo imaging. We showed that LuCaP 136 spheroids formed intratibial, orthotopic, and subcutaneous tumors when re-introduced into mice. Intratibial tumors responded to castration and were highly osteosclerotic. LuCaP 136 is a realistic in vitro-in vivo preclinical model of a subtype of bone metastatic prostate cancer.
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http://dx.doi.org/10.1007/s10585-016-9781-2DOI Listing
April 2016

Organ-Preserving Surgical Treatment of a Horseshoe Kidney Occupied by a Large Renal Cell Carcinoma with Extensive Venous Invasion: A Case Report.

Urol Int 2018 11;100(2):245-247. Epub 2016 Feb 11.

Department of Urology, Saarland University Medical Center, Homburg/Saar, Germany.

The horseshoe kidney is one of the most common congenital disorders affecting the urogenital system. Following a fusion of the lower kidney poles, which in turn lead to the formation of an isthmus, this anatomical variation is accompanied by other characteristic properties like an incomplete ascension, ventral rotation of the pelvices as well as atypical vascular supply. Even though renal carcinoids and Wilms tumors are more common in horseshoe kidneys, the incidence of renal cell carcinomas seems to be unaffected. Here we report the case of a locally advanced renal cell carcinoma with extensive venous invasion occurring in a horseshoe kidney and its complex surgical management. The whole primary tumor as well as a majority of venous tumor thrombi could be removed by a combination of 2/3 nephrectomy and cavotomy with thrombectomy. During 1 year of follow-up, the patient neither suffered from a tumor relapse, nor did he require renal replacement therapy. Thus, we conclude that even in cases of RCC where advanced disease is associated with complex anatomical situations, organ-preserving surgical treatment should be pursued to achieve excellent functional and oncological results.
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http://dx.doi.org/10.1159/000443671DOI Listing
September 2018

Orthotopic tumorgrafts in nude mice: A new method to study human prostate cancer.

Prostate 2015 Oct 12;75(14):1526-37. Epub 2015 Jun 12.

Institute for Clinical and Experimental Surgery, Saarland University, Homburg/Saar, Germany.

Background: In vivo model systems in prostate cancer research that authentically reproduce tumor growth are still sparse. While orthotopic implantation is technically difficult, particularly in the mouse, most models favor subcutaneous tumor growth. This however provides little information about natural tumor growth behavior and tumor stroma interaction. Furthermore, established prostate cancer cell lines grown as in vivo xenografts are not able to reflect the variety of tumor specific growth patterns and growth behavior in men. Primary cell cultures are difficult to handle and an induction of orthotopic tumors has not been successful yet. Therefore, a tumorgraft model using tumor tissue from prostatectomy specimens was developed.

Methods: Balb/c nude mice were used to graft fresh prostate tumor tissue by renal subcapsular and orthotopic implantation. Testosterone propionate was supplemented. Animals were tracked by means of 30 MHz ultrasound to monitor tumor engraftment and growth. Autopsy, histology, PSA measurements as well as immunostaining and PCR for human tissue were performed to confirm orthotopic tumor growth.

Results: Renal subcapsular engraftment was seen in 2 of 3 mice. Orthotopic engraftment was observed in 7 of 11 animals (63.6%) with an overall engraftment of 5 out of 9 patient specimens (55.6%). Ultrasound confirmed the tumor growth over time. Of interest, the tumorgrafts not only retained essential features of the parental tumors, but also stained positive for tumor specific markers such as AR, PSA, and AMACR. Tumor positive animals showed highly elevated serum PSA levels with confirmation of a human specific PCR sequence and a human endothelial cell lining in the tumor vessels.

Conclusions: Standardized implantation of fresh tumor tissue in nude mice prostates generates tumorgrafts with histological properties of organ-confined prostate cancer. These tumorgrafts display a new approach for an optimized in vivo model of prostate cancer and will allow further investigations on specific pathways of tumor initiation and progression as well as therapeutic response.
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http://dx.doi.org/10.1002/pros.23027DOI Listing
October 2015

Structure of the mammalian oligosaccharyl-transferase complex in the native ER protein translocon.

Nat Commun 2014 ;5:3072

Department of Molecular Structural Biology, Max-Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany.

In mammalian cells, proteins are typically translocated across the endoplasmic reticulum (ER) membrane in a co-translational mode by the ER protein translocon, comprising the protein-conducting channel Sec61 and additional complexes involved in nascent chain processing and translocation. As an integral component of the translocon, the oligosaccharyl-transferase complex (OST) catalyses co-translational N-glycosylation, one of the most common protein modifications in eukaryotic cells. Here we use cryoelectron tomography, cryoelectron microscopy single-particle analysis and small interfering RNA-mediated gene silencing to determine the overall structure, oligomeric state and position of OST in the native ER protein translocon of mammalian cells in unprecedented detail. The observed positioning of OST in close proximity to Sec61 provides a basis for understanding how protein translocation into the ER and glycosylation of nascent proteins are structurally coupled. The overall spatial organization of the native translocon, as determined here, serves as a reliable framework for further hypothesis-driven studies.
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http://dx.doi.org/10.1038/ncomms4072DOI Listing
November 2015

Targeting cell migration and the endoplasmic reticulum stress response with calmodulin antagonists: a clinically tested small molecule phenocopy of SEC62 gene silencing in human tumor cells.

BMC Cancer 2013 Dec 5;13:574. Epub 2013 Dec 5.

Department of Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Saarland, Germany.

Background: Tumor cells benefit from their ability to avoid apoptosis and invade other tissues. The endoplasmic reticulum (ER) membrane protein Sec62 is a key player in these processes. Sec62 is essential for cell migration and protects tumor cells against thapsigargin-induced ER stress, which are both linked to cytosolic Ca²⁺. SEC62 silencing leads to elevated cytosolic Ca²⁺ and increased ER Ca²⁺ leakage after thapsigargin treatment. Sec62 protein levels are significantly increased in different tumors, including prostate, lung and thyroid cancer.

Methods: In lung cancer, the influence of Sec62 protein levels on patient survival was analyzed using the Kaplan-Meier method and log-rank test. To elucidate the underlying pathophysiological functions of Sec62, Ca²⁺ imaging techniques, real-time cell analysis and cell migration assays were performed. The effects of treatment with the calmodulin antagonists, trifluoperazine (TFP) and ophiobolin A, on cellular Ca²⁺ homeostasis, cell growth and cell migration were compared with the effects of siRNA-mediated Sec62 depletion or the expression of a mutated SEC62 variant in vitro. Using Biacore analysis we examined the Ca²⁺-sensitive interaction of Sec62 with the Sec61 complex.

Results: Sec62 overproduction significantly correlated with reduced patient survival. Therefore, Sec62 is not only a predictive marker for this type of tumor, but also an interesting therapeutic target. The present study suggests a regulatory function for Sec62 in the major Ca²⁺ leakage channel in the ER, Sec61, by a direct and Ca²⁺-sensitive interaction. A Ca²⁺-binding motif in Sec62 is essential for its molecular function. Treatment of cells with calmodulin antagonists mimicked Sec62 depletion by inhibiting cell migration and rendering the cells sensitive to thapsigargin treatment.

Conclusions: Targeting tumors that overproduce Sec62 with calmodulin antagonists in combination with targeted thapsigargin analogues may offer novel personalized therapeutic options.
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http://dx.doi.org/10.1186/1471-2407-13-574DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3878975PMC
December 2013

Analysis of protein translocation into the endoplasmic reticulum of human cells.

Methods Mol Biol 2013 ;1033:285-99

Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany.

The development of small-interfering RNA (siRNA)-mediated gene-silencing strategies has made it possible to study the transport of precursors of soluble and membrane proteins into the endoplasmic reticulum (ER) of human cells. In these approaches, a certain target gene is silenced in the cell type of choice, followed by analysis of the effect of this silencing on the biogenesis of a single or set of precursor polypeptide(s) in cell culture or in cell-free assays involving semi-permeabilized cells and in vitro translations systems. These approaches allow for functional analysis of components of the ER-resident protein transport machinery as well as the elucidation of their potential cell-type variations and regulatory mechanisms. The gene-silencing and subsequent plasmid-based complementation carries the additional benefit of facilitating analysis of the consequences of disease-linked mutations in ER transport components.
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http://dx.doi.org/10.1007/978-1-62703-487-6_18DOI Listing
March 2014

BiP-mediated closing of the Sec61 channel limits Ca2+ leakage from the ER.

EMBO J 2012 Aug 13;31(15):3282-96. Epub 2012 Jul 13.

Department of Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany.

In mammalian cells, signal peptide-dependent protein transport into the endoplasmic reticulum (ER) is mediated by a dynamic protein-conducting channel, the Sec61 complex. Previous work has characterized the Sec61 channel as a potential ER Ca(2+) leak channel and identified calmodulin as limiting Ca(2+) leakage in a Ca(2+)-dependent manner by binding to an IQ motif in the cytosolic aminoterminus of Sec61α. Here, we manipulated the concentration of the ER lumenal chaperone BiP in cells in different ways and used live cell Ca(2+) imaging to monitor the effects of reduced levels of BiP on ER Ca(2+) leakage. Regardless of how the BiP concentration was lowered, the absence of available BiP led to increased Ca(2+) leakage via the Sec61 complex. When we replaced wild-type Sec61α with mutant Sec61αY344H in the same model cell, however, Ca(2+) leakage from the ER increased and was no longer affected by manipulation of the BiP concentration. Thus, BiP limits ER Ca(2+) leakage through the Sec61 complex by binding to the ER lumenal loop 7 of Sec61α in the vicinity of tyrosine 344.
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http://dx.doi.org/10.1038/emboj.2012.189DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3411083PMC
August 2012

Sec62 bridges the gap from 3q amplification to molecular cell biology in non-small cell lung cancer.

Am J Pathol 2012 Feb 21;180(2):473-83. Epub 2011 Dec 21.

Department of Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany.

The molecular carcinogenesis of lung cancer has yet to be clearly elucidated. We investigated the possible oncogenic function of SEC62 in lung cancer, which was predicted based on our previous findings that lung and thyroid cancer tissue samples exhibited increased Sec62 protein levels. The SEC62 gene locus is at 3q26.2, and 3q amplification is reportedly the most common genomic alteration in non-small cell lung cancer. We analyzed SEC62 mRNA and protein levels in tissue samples from lung cancer patients by real-time quantitative PCR, Western blot, and IHC and found significantly increased SEC62 mRNA and protein levels in tumors compared with tumor-free tissue samples from the same patients. Correlation analyses revealed significantly higher Sec62 levels in tumors with lymph node metastases compared with nonmetastatic tumors, as well as in poorly compared with moderately differentiated tumors. On the basis of these promising results, we examined the role of Sec62 in cancer cell biology in vitro. Cell migration assays with lung and thyroid cancer cells showed distinct stimulation of migration in SEC62-overexpressing cells and inhibition of migration in Sec62-depleted cells. Moreover, we found that SEC62 silencing sensitized the cells to thapsigargin-induced endoplasmic reticulum stress. Thus, our results indicate that SEC62 represents a potential candidate oncogene in the amplified 3q region in cases of non-small cell lung cancer and harbors various functions in cancer cell biology.
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http://dx.doi.org/10.1016/j.ajpath.2011.10.039DOI Listing
February 2012