Publications by authors named "Steven T Sizemore"

20 Publications

  • Page 1 of 1

Pten regulates collagen fibrillogenesis by fibroblasts through SPARC.

PLoS One 2021 3;16(2):e0245653. Epub 2021 Feb 3.

Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, United States of America.

Collagen deposition contributes to both high mammographic density and breast cancer progression. Low stromal PTEN expression has been observed in as many as half of breast tumors and is associated with increases in collagen deposition, however the mechanism connecting PTEN loss to increased collagen deposition remains unclear. Here, we demonstrate that Pten knockout in fibroblasts using an Fsp-Cre;PtenloxP/loxP mouse model increases collagen fiber number and fiber size within the mammary gland. Pten knockout additionally upregulated Sparc transcription in fibroblasts and promoted collagen shuttling out of the cell. Interestingly, SPARC mRNA expression was observed to be significantly elevated in the tumor stroma as compared to the normal breast in several patient cohorts. While SPARC knockdown via shRNA did not affect collagen shuttling, it notably decreased assembly of exogenous collagen. In addition, SPARC knockdown decreased fibronectin assembly and alignment of the extracellular matrix in an in vitro fibroblast-derived matrix model. Overall, these data indicate upregulation of SPARC is a mechanism by which PTEN regulates collagen deposition in the mammary gland stroma.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0245653PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7857610PMC
February 2021

The transcriptional repressor BCL11A promotes breast cancer metastasis.

J Biol Chem 2020 08 23;295(33):11707-11719. Epub 2020 Jun 23.

Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA

The phenotypes of each breast cancer subtype are defined by their transcriptomes. However, the transcription factors that regulate differential patterns of gene expression that contribute to specific disease outcomes are not well understood. Here, using gene silencing and overexpression approaches, RNA-Seq, and splicing analysis, we report that the transcription factor B-cell leukemia/lymphoma 11A (BCL11A) is highly expressed in triple-negative breast cancer (TNBC) and drives metastatic disease. Moreover, BCL11A promotes cancer cell invasion by suppressing the expression of muscleblind-like splicing regulator 1 (), a splicing regulator that suppresses metastasis. This ultimately increases the levels of an alternatively spliced isoform of integrin-α6 (), which is associated with worse patient outcomes. These results suggest that BCL11A sustains TNBC cell invasion and metastatic growth by repressing MBNL1-directed splicing of Our findings also indicate that BCL11A lies at the interface of transcription and splicing and promotes aggressive TNBC phenotypes.
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http://dx.doi.org/10.1074/jbc.RA120.014018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7450125PMC
August 2020

A Genome-Wide Pooled shRNA Screen Identifies PPP2R2A as a Predictive Biomarker for the Response to ATR and CHK1 Inhibitors.

Cancer Res 2020 08 10;80(16):3305-3318. Epub 2020 Jun 10.

Department of Radiation Oncology, The Ohio State University James Comprehensive Cancer Center and College of Medicine, Ohio.

There is currently a lack of precise predictive biomarkers for patient selection in clinical trials of inhibitors targeting replication stress (RS) response proteins ATR and CHK1. The objective of this study was to identify novel predictive biomarkers for the response to these agents in treating non-small cell lung cancer (NSCLC). A genome-wide loss-of-function screen revealed that tumor suppressor PPP2R2A, a B regulatory subunit of protein phosphatase 2 (PP2A), determines sensitivity to CHK1 inhibition. A synthetic lethal interaction between PPP2R2A deficiency and ATR or CHK1 inhibition was observed in NSCLC and and was independent of p53 status. ATR and CHK1 inhibition resulted in significantly increased levels of RS and altered replication dynamics, particularly in PPP2R2A-deficient NSCLC cells. Mechanistically, PPP2R2A negatively regulated translation of oncogene c-Myc protein. c-Myc activity was required for PPP2R2A deficiency-induced alterations of replication initiation/RS and sensitivity to ATR/CHK1 inhibitors. We conclude that PPP2R2A deficiency elevates RS by upregulating c-Myc activity, rendering cells reliant on the ATR/CHK1 axis for survival. Our studies show a novel synthetic lethal interaction and identify PPP2R2A as a potential new predictive biomarker for patient stratification in the clinical use of ATR and CHK1 inhibitors. SIGNIFICANCE: This study reveals new approaches to specifically target PPP2R2A-deficient lung cancer cells and provides a novel biomarker that will significantly improve treatment outcome with ATR and CHK1 inhibitors.
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http://dx.doi.org/10.1158/0008-5472.CAN-20-0057DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7518641PMC
August 2020

Pathological Analysis of Lung Metastasis Following Lateral Tail-Vein Injection of Tumor Cells.

J Vis Exp 2020 05 20(159). Epub 2020 May 20.

Department of Radiation Oncology, Arthur G. James Comprehensive Cancer Center and Richard L. Solove Research Institute, The Ohio State University Medical Center;

Metastasis, the primary cause of morbidity and mortality for most cancer patients, can be challenging to model preclinically in mice. Few spontaneous metastasis models are available. Thus, the experimental metastasis model involving tail-vein injection of suitable cell lines is a mainstay of metastasis research. When cancer cells are injected into the lateral tail-vein, the lung is their preferred site of colonization. A potential limitation of this technique is the accurate quantification of the metastatic lung tumor burden. While some investigators count macrometastases of a pre-defined size and/or include micrometastases following sectioning of tissue, others determine the area of metastatic lesions relative to normal tissue area. Both of these quantification methods can be exceedingly difficult when the metastatic burden is high. Herein, we demonstrate an intravenous injection model of lung metastasis followed by an advanced method for quantifying metastatic tumor burden using image analysis software. This process allows for investigation of multiple end-point parameters, including average metastasis size, total number of metastases, and total metastasis area, to provide a comprehensive analysis. Furthermore, this method has been reviewed by a veterinary pathologist board-certified by the American College of Veterinary Pathologists (SEK) to ensure accuracy.
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http://dx.doi.org/10.3791/61270DOI Listing
May 2020

Stromal Platelet-Derived Growth Factor Receptor-β Signaling Promotes Breast Cancer Metastasis in the Brain.

Cancer Res 2021 Feb 23;81(3):606-618. Epub 2020 Apr 23.

The Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio.

Platelet-derived growth factor receptor-beta (PDGFRβ) is a receptor tyrosine kinase found in cells of mesenchymal origin such as fibroblasts and pericytes. Activation of this receptor is dependent on paracrine ligand induction, and its preferred ligand PDGFB is released by neighboring epithelial and endothelial cells. While expression of both PDGFRβ and PDGFB has been noted in patient breast tumors for decades, how PDGFB-to-PDGFRβ tumor-stroma signaling mediates breast cancer initiation, progression, and metastasis remains unclear. Here we demonstrate this paracrine signaling pathway that mediates both primary tumor growth and metastasis, specifically, metastasis to the brain. Elevated levels of PDGFB accelerated orthotopic tumor growth and intracranial growth of mammary tumor cells, while mesenchymal-specific expression of an activating mutant PDGFRβ (PDGFRβ) exerted proproliferative signals on adjacent mammary tumor cells. Stromal expression of PDGFRβ also promoted brain metastases of mammary tumor cells expressing high PDGFB when injected intravenously. In the brain, expression of PDGFRβ was observed within a subset of astrocytes, and aged mice expressing PDGFRβ exhibited reactive gliosis. Importantly, the PDGFR-specific inhibitor crenolanib significantly reduced intracranial growth of mammary tumor cells. In a tissue microarray comprised of 363 primary human breast tumors, high PDGFB protein expression was prognostic for brain metastases, but not metastases to other sites. Our results advocate the use of mice expressing PDGFRβ in their stromal cells as a preclinical model of breast cancer-associated brain metastases and support continued investigation into the clinical prognostic and therapeutic use of PDGFB-to-PDGFRβ signaling in women with breast cancer. SIGNIFICANCE: These studies reveal a previously unknown role for PDGFB-to-PDGFRβ paracrine signaling in the promotion of breast cancer brain metastases and support the prognostic and therapeutic clinical utility of this pathway for patients..
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http://dx.doi.org/10.1158/0008-5472.CAN-19-3731DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7581545PMC
February 2021

LIN9 and NEK2 Are Core Regulators of Mitotic Fidelity That Can Be Therapeutically Targeted to Overcome Taxane Resistance.

Cancer Res 2020 04 13;80(8):1693-1706. Epub 2020 Feb 13.

Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio.

A significant therapeutic challenge for patients with cancer is resistance to chemotherapies such as taxanes. Overexpression of LIN9, a transcriptional regulator of cell-cycle progression, occurs in 65% of patients with triple-negative breast cancer (TNBC), a disease commonly treated with these drugs. Here, we report that LIN9 is further elevated with acquisition of taxane resistance. Inhibiting LIN9 genetically or by suppressing its expression with a global BET inhibitor restored taxane sensitivity by inducing mitotic progression errors and apoptosis. While sustained LIN9 is necessary to maintain taxane resistance, there are no inhibitors that directly repress its function. Hence, we sought to discover a druggable downstream transcriptional target of LIN9. Using a computational approach, we identified NIMA-related kinase 2 (NEK2), a regulator of centrosome separation that is also elevated in taxane-resistant cells. High expression of was predictive of low survival rates in patients who had residual disease following treatment with taxanes plus an anthracycline, suggesting a role for this kinase in modulating taxane sensitivity. Like LIN9, genetic or pharmacologic blockade of NEK2 activity in the presence of paclitaxel synergistically induced mitotic abnormalities in nearly 100% of cells and completely restored sensitivity to paclitaxel, . In addition, suppressing NEK2 activity with two distinct small molecules potentiated taxane response in multiple models of TNBC, including a patient-derived xenograft, without inducing toxicity. These data demonstrate that the LIN9/NEK2 pathway is a therapeutically targetable mediator of taxane resistance that can be leveraged to improve response to this core chemotherapy. SIGNIFICANCE: Resistance to chemotherapy is a major hurdle for treating patients with cancer. Combining NEK2 inhibitors with taxanes may be a viable approach for improving patient outcomes by enhancing mitotic defects induced by taxanes alone.
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http://dx.doi.org/10.1158/0008-5472.CAN-19-3466DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7165041PMC
April 2020

NEDD4 expression is associated with breast cancer progression and is predictive of a poor prognosis.

Breast Cancer Res 2019 12 19;21(1):148. Epub 2019 Dec 19.

Department of Breast Surgery, The First Affiliated Hospital, Sun Yat-sen University, No.58 of Zhongshan 2nd Road, Yuexiu District, Guangzhou, 510080, China.

Background: A role for neural precursor cell-expressed developmentally downregulated gene 4 (NEDD4) in tumorigenesis has been suggested. However, information is lacking on its role in breast tumor biology. The purpose of this study was to determine the role of NEDD4 in the promotion of the growth and progression of breast cancer (BC) and to evaluate the clinicopathologic and prognostic significance of NEDD4.

Methods: The impact of NEDD4 expression in BC cell growth was determined by Cell Counting Kit-8 and colony formation assays. Formalin-fixed paraffin-embedded specimens were collected from 133 adjacent normal tissues (ANTs), 445 BC cases composed of pre-invasive ductal carcinoma in situ (DCIS, n = 37), invasive ductal carcinomas (IDC, n = 408, 226 without and 182 with lymph node metastasis), and 116 invaded lymph nodes. The expression of NEDD4 was analyzed by immunohistochemistry. The association between NEDD4 expression and clinicopathological characteristics was analyzed by chi-square test. Survival was evaluated using the Kaplan-Meier method, and curves were compared using a log-rank test. Univariate and multivariate analyses were performed using the Cox regression method.

Results: NEDD4 promoted BC growth in vitro. In clinical retrospective studies, 16.5% of ANTs (22/133) demonstrated positive NEDD4 staining. Strikingly, the proportion of cases showing NEDD4-positive staining increased to 51.4% (19/37) in DCIS, 58.4% (132/226) in IDC without lymph node metastasis, and 73.1% (133/182) in BC with lymph node metastasis (BCLNM). In addition, NEDD4-positive staining was associated with clinical parameters, including tumor size (P = 0.030), nodal status (P = 0.001), estrogen receptor status (P = 0.035), and progesterone receptor status (P = 0.023). Moreover, subset analysis in BCLNM revealed that high NEDD4 expression correlated with an elevated risk of relapse (P = 0.0276). Further, NEDD4 expression was an independent prognostic predictor. Lastly, the rates for 10-year overall survival and disease-free survival were significantly lower in patients with positive NEDD4 staining than those in BC patients with negative NEDD4 staining BC (P = 0.0024 and P = 0.0011, respectively).

Conclusions: NEDD4 expression is elevated in BC and is associated with BC growth. NEDD4 correlated with clinicopathological parameters and predicts a poor prognosis. Thus, NEDD4 is a potential biomarker of poor prognosis and a potential therapeutic target for BC treatment.
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http://dx.doi.org/10.1186/s13058-019-1236-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6923956PMC
December 2019

Pyruvate kinase M2 regulates homologous recombination-mediated DNA double-strand break repair.

Cell Res 2018 11 8;28(11):1090-1102. Epub 2018 Oct 8.

Department of Radiation Oncology, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, USA.

Resistance to genotoxic therapies is a primary cause of treatment failure and tumor recurrence. The underlying mechanisms that activate the DNA damage response (DDR) and allow cancer cells to escape the lethal effects of genotoxic therapies remain unclear. Here, we uncover an unexpected mechanism through which pyruvate kinase M2 (PKM2), the highly expressed PK isoform in cancer cells and a master regulator of cancer metabolic reprogramming, integrates with the DDR to directly promote DNA double-strand break (DSB) repair. In response to ionizing radiation and oxidative stress, ATM phosphorylates PKM2 at T328 resulting in its nuclear accumulation. pT328-PKM2 is required and sufficient to promote homologous recombination (HR)-mediated DNA DSB repair through phosphorylation of CtBP-interacting protein (CtIP) on T126 to increase CtIP's recruitment at DSBs and resection of DNA ends. Disruption of the ATM-PKM2-CtIP axis sensitizes cancer cells to a variety of DNA-damaging agents and PARP1 inhibition. Furthermore, increased nuclear pT328-PKM2 level is associated with significantly worse survival in glioblastoma patients. Combined, these data advocate the use of PKM2-targeting strategies as a means to not only disrupt cancer metabolism but also inhibit an important mechanism of resistance to genotoxic therapies.
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http://dx.doi.org/10.1038/s41422-018-0086-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6218445PMC
November 2018

Stromal PTEN determines mammary epithelial response to radiotherapy.

Nat Commun 2018 07 17;9(1):2783. Epub 2018 Jul 17.

Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, 29425, USA.

The importance of the tumor-associated stroma in cancer progression is clear. However, it remains uncertain whether early events in the stroma are capable of initiating breast tumorigenesis. Here, we show that in the mammary glands of non-tumor bearing mice, stromal-specific phosphatase and tensin homolog (Pten) deletion invokes radiation-induced genomic instability in neighboring epithelium. In these animals, a single dose of whole-body radiation causes focal mammary lobuloalveolar hyperplasia through paracrine epidermal growth factor receptor (EGFR) activation, and EGFR inhibition abrogates these cellular changes. By analyzing human tissue, we discover that stromal PTEN is lost in a subset of normal breast samples obtained from reduction mammoplasty, and is predictive of recurrence in breast cancer patients. Combined, these data indicate that diagnostic or therapeutic chest radiation may predispose patients with decreased stromal PTEN expression to secondary breast cancer, and that prophylactic EGFR inhibition may reduce this risk.
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http://dx.doi.org/10.1038/s41467-018-05266-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6050339PMC
July 2018

Synthetic Lethality of PARP Inhibition and Ionizing Radiation is p53-dependent.

Mol Cancer Res 2018 07 28;16(7):1092-1102. Epub 2018 Mar 28.

Department of Radiation Oncology, University of Arkansas for Medical Sciences, Little Rock, Arkansas.

PARP inhibitors (PARPi) are potentially effective therapeutic agents capable of inducing synthetic lethality in tumors with deficiencies in homologous recombination (HR)-mediated DNA repair such as those carrying BRCA1 mutations. However, BRCA mutations are rare, the majority of tumors are proficient in HR repair, and thus most tumors are resistant to PARPi. Previously, we observed that ionizing radiation (IR) initiates cytoplasmic translocation of BRCA1 leading to suppression of HR-mediated DNA repair and induction of synthetic PARPi lethality in wild-type BRCA1 and HR-proficient tumor cells. The tumor suppressor p53 was identified as a key factor that regulates DNA damage-induced BRCA1 cytoplasmic sequestration following IR. However, the role of p53 in IR-induced PARPi sensitization remains unclear. This study elucidates the role of p53 in IR-induced PARPi cytotoxicity in HR-proficient cancer cells and suggests p53 status may help define a patient population that might benefit from this treatment strategy. Sensitization to PARPi following IR was determined and utilizing human breast and glioma tumor cells carrying wild-type BRCA1 and p53, and in associated cells in which p53 function was modified by knockdown or mutation. In breast and glioma cells with proficient HR repair, IR-induced BRCA1 cytoplasmic sequestration, HR repair inhibition, and subsequent PARPi sensitization and was dependent upon functional p53. Implications: p53 status determines PARP inhibitor sensitization by ionizing radiation in multiple BRCA1 and HR-proficient tumor types and may predict which patients are most likely to benefit from combination therapy. .
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http://dx.doi.org/10.1158/1541-7786.MCR-18-0106DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6713455PMC
July 2018

Mitotic Vulnerability in Triple-Negative Breast Cancer Associated with LIN9 Is Targetable with BET Inhibitors.

Cancer Res 2017 10 14;77(19):5395-5408. Epub 2017 Aug 14.

Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio.

Triple-negative breast cancers (TNBC) are highly aggressive, lack FDA-approved targeted therapies, and frequently recur, making the discovery of novel therapeutic targets for this disease imperative. Our previous analysis of the molecular mechanisms of action of bromodomain and extraterminal protein inhibitors (BETi) in TNBC revealed these drugs cause multinucleation, indicating BET proteins are essential for efficient mitosis and cytokinesis. Here, using live cell imaging, we show that BET inhibition prolonged mitotic progression and induced mitotic cell death, both of which are indicative of mitotic catastrophe. Mechanistically, the mitosis regulator was a direct target of BET proteins that mediated the effects of BET proteins on mitosis in TNBC. Although BETi have been proposed to function by dismantling super-enhancers (SE), the gene lacks an SE but was amplified or overexpressed in the majority of TNBCs. In addition, its mRNA expression predicted poor outcome across breast cancer subtypes. Together, these results provide a mechanism for cancer selectivity of BETi that extends beyond modulation of SE-associated genes and suggest that cancers dependent upon LIN9 overexpression may be particularly vulnerable to BETi. .
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http://dx.doi.org/10.1158/0008-5472.CAN-17-1571DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5626629PMC
October 2017

Follistatin is a metastasis suppressor in a mouse model of HER2-positive breast cancer.

Breast Cancer Res 2017 06 5;19(1):66. Epub 2017 Jun 5.

Department of Pharmacology, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH, 44106-4965, USA.

Background: Follistatin (FST) is an intrinsic inhibitor of activin, a member of the transforming growth factor-β superfamily of ligands. The prognostic value of FST and its family members, the follistatin-like (FSTL) proteins, have been studied in various cancers. However, these studies, as well as limited functional analyses of the FSTL proteins, have yielded conflicting results on the role of these proteins in disease progression. Furthermore, very few have been focused on FST itself. We assessed whether FST may be a suppressor of tumorigenesis and/or metastatic progression in breast cancer.

Methods: Using publicly available gene expression data, we examined the expression patterns of FST and INHBA, a subunit of activin, in normal and cancerous breast tissue and the prognostic value of FST in breast cancer metastases, recurrence-free survival, and overall survival. The functional effects of activin and FST on in vitro proliferation, migration, and invasion of breast cancer cells were also examined. FST overexpression in an autochthonous mouse model of breast cancer was then used to assess the in vivo impact of FST on metastatic progression.

Results: Examination of multiple breast cancer datasets revealed that FST expression is reduced in breast cancers compared with normal tissue and that low FST expression predicts increased metastasis and reduced overall survival. FST expression was also reduced in a mouse model of HER2/Neu-induced metastatic breast cancer. We found that FST blocks activin-induced breast epithelial cell migration in vitro, suggesting that its loss may promote breast cancer aggressiveness. To directly determine if FST restoration could inhibit metastatic progression, we transgenically expressed FST in the HER2/Neu model. Although FST had no impact on tumor initiation or growth, it completely blocked the formation of lung metastases.

Conclusions: These data indicate that FST is a bona fide metastasis suppressor in this mouse model and support future efforts to develop an FST mimetic to suppress metastatic progression.
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http://dx.doi.org/10.1186/s13058-017-0857-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5460489PMC
June 2017

Stromal PDGFR-α Activation Enhances Matrix Stiffness, Impedes Mammary Ductal Development, and Accelerates Tumor Growth.

Neoplasia 2017 Jun 11;19(6):496-508. Epub 2017 May 11.

The Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210, USA; Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH 43210, USA. Electronic address:

The extracellular matrix (ECM) is critical for mammary ductal development and differentiation, but how mammary fibroblasts regulate ECM remodeling remains to be elucidated. Herein, we used a mouse genetic model to activate platelet derived growth factor receptor-alpha (PDGFRα) specifically in the stroma. Hyperactivation of PDGFRα in the mammary stroma severely hindered pubertal mammary ductal morphogenesis, but did not interrupt the lobuloalveolar differentiation program. Increased stromal PDGFRα signaling induced mammary fat pad fibrosis with a corresponding increase in interstitial hyaluronic acid (HA) and collagen deposition. Mammary fibroblasts with PDGFRα hyperactivation also decreased hydraulic permeability of a collagen substrate in an in vitro microfluidic device assay, which was mitigated by inhibition of either PDGFRα or HA. Fibrosis seen in this model significantly increased the overall stiffness of the mammary gland as measured by atomic force microscopy. Further, mammary tumor cells injected orthotopically in the fat pads of mice with stromal activation of PDGFRα grew larger tumors compared to controls. Taken together, our data establish that aberrant stromal PDGFRα signaling disrupts ECM homeostasis during mammary gland development, resulting in increased mammary stiffness and increased potential for tumor growth.
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http://dx.doi.org/10.1016/j.neo.2017.04.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5440288PMC
June 2017

Changes in BAI1 and nestin expression are prognostic indicators for survival and metastases in breast cancer and provide opportunities for dual targeted therapies.

Mol Cancer Ther 2015 Jan 5;14(1):307-14. Epub 2014 Nov 5.

Department of Neurological Surgery, James Comprehensive Cancer Center, The Ohio State University Medical Center, Columbus, Ohio. Department of Radiation Oncology, James Comprehensive Cancer Center, The Ohio State University Medical Center, Columbus, Ohio.

The 2-year survival rate of patients with breast cancer brain metastases is less than 2%. Treatment options for breast cancer brain metastases are limited, and there is an unmet need to identify novel therapies for this disease. Brain angiogenesis inhibitor 1 (BAI1) is a GPCR involved in tumor angiogenesis, invasion, phagocytosis, and synaptogenesis. For the first time, we identify that BAI1 expression is significantly reduced in breast cancer and higher expression is associated with better patient survival. Nestin is an intermediate filament whose expression is upregulated in several cancers. We found that higher Nestin expression significantly correlated with breast cancer lung and brain metastases, suggesting both BAI1 and Nestin can be therapeutic targets for this disease. Here, we demonstrate the ability of an oncolytic virus, 34.5ENVE, to target and kill high Nestin-expressing cells and deliver Vstat120 (extracellular fragment of BAI1). Finally, we created two orthotopic immune-competent murine models of breast cancer brain metastases and demonstrated 34.5ENVE extended the survival of immune-competent mice bearing intracranial breast cancer tumors.
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http://dx.doi.org/10.1158/1535-7163.MCT-14-0659DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4297221PMC
January 2015

GABA(A) receptor pi (GABRP) stimulates basal-like breast cancer cell migration through activation of extracellular-regulated kinase 1/2 (ERK1/2).

J Biol Chem 2014 Aug 10;289(35):24102-13. Epub 2014 Jul 10.

From the Departments of Pharmacology and Genetics and Division of General Medical Sciences-Oncology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106

Breast cancer is a heterogeneous disease comprised of distinct subtypes predictive of patient outcome. Tumors of the basal-like subtype have a poor prognosis due to inherent aggressiveness and the lack of targeted therapeutics. Basal-like tumors typically lack estrogen receptor-α, progesterone receptor and HER2/ERBB2, or in other words they are triple negative (TN). Continued evaluation of basal-like breast cancer (BLBC) biology is essential to identify novel therapeutic targets. Expression of the pi subunit of the GABA(A) receptor (GABRP) is associated with the BLBC/TN subtype, and herein, we reveal its expression also correlates with metastases to the brain and poorer patient outcome. GABRP expression in breast cancer cell lines also demonstrates a significant correlation with the basal-like subtype suggesting that GABRP functions in the initiation and/or progression of basal-like tumors. To address this postulate, we stably silenced GABRP in two BLBC cell lines, HCC1187 and HCC70 cells. Decreased GABRP reduces in vitro tumorigenic potential and migration concurrent with alterations in the cytoskeleton, specifically diminished cellular protrusions and expression of the BLBC-associated cytokeratins, KRT5, KRT6B, KRT14, and KRT17. Silencing GABRP also decreases phosphorylation of extracellular regulated kinase 1/2 (ERK1/2) in both cell lines and selective inhibition of ERK1/2 similarly decreases the basal-like cytokeratins as well as migration. Combined, these data reveal a GABRP-ERK1/2-cytokeratin axis that maintains the migratory phenotype of basal-like breast cancer. GABRP is a component of a cell surface receptor, thus, these findings suggest that targeting this new signaling axis may have therapeutic potential in BLBC.
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http://dx.doi.org/10.1074/jbc.M114.593582DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4148843PMC
August 2014

Hypomethylation of the MMP7 promoter and increased expression of MMP7 distinguishes the basal-like breast cancer subtype from other triple-negative tumors.

Breast Cancer Res Treat 2014 Jul 22;146(1):25-40. Epub 2014 May 22.

Department of Pharmacology, Case Western Reserve University School of Medicine, 10900 Euclid Ave., Cleveland, OH, 44106-4965, USA.

Identification of novel targets for the treatment of basal-like breast cancer is essential for improved outcomes in patients with this disease. This study investigates the association of MMP7 expression and MMP7 promoter methylation with subtype and outcome in breast cancer patient cohorts. Immunohistochemical analysis was performed on a breast cancer tissue microarray and validated in independent histological samples. MMP7 expression significantly correlated with patient age, tumor size, triple-negative (TN) status, and recurrence. Analysis of publically available datasets confirmed MMP7 gene expression as a prognostic marker of breast cancer metastasis, particularly metastasis to the brain and lungs. Methylation of the MMP7 promoter was assessed by methylation-specific PCR in a panel of breast cancer cell lines and patient tumor samples. Hypomethylation of the MMP7 promoter significantly correlated with TN status in DNA from patient tumor samples, and this association was confirmed using The Cancer Genome Atlas (TCGA) dataset. Evaluation of a panel of breast cancer cell lines and data from the Curtis and TCGA breast carcinoma datasets revealed that elevated MMP7 expression and MMP7 promoter hypomethylation are specific biomarkers of the basal-like molecular subtype which shares considerable, but not complete, overlap with the clinical TN subtype. Importantly, MMP7 expression was identified as an independent predictor of pathological complete response in a large breast cancer patient cohort. Combined, these data suggest that MMP7 expression and MMP7 promoter methylation may be useful as prognostic biomarkers. Furthermore, MMP7 expression and promoter methylation analysis may be effective mechanisms to distinguish basal-like breast cancers from other triple-negative subtypes. Finally, these data implicate MMP7 as a potential therapeutic target for the treatment of basal-like breast cancers.
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http://dx.doi.org/10.1007/s10549-014-2989-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4716673PMC
July 2014

Protein kinase C Beta in the tumor microenvironment promotes mammary tumorigenesis.

Front Oncol 2014 23;4:87. Epub 2014 Apr 23.

Department of Molecular and Cellular Biochemistry, College of Medicine, The Ohio State University , Columbus, OH , USA ; Comprehensive Cancer Center, The Ohio State University , Columbus, OH , USA.

Protein kinase C beta (PKCβ) expression in breast cancer is associated with a more aggressive tumor phenotype, yet the mechanism for how PKCβ is pro-tumorigenic in this disease is still unclear. Interestingly, while it is known that PKCβ mediates angiogenesis, immunity, fibroblast function and adipogenesis, all components of the mammary tumor microenvironment (TME), no study to date has investigated whether stromal PKCβ is functionally relevant in breast cancer. Herein, we evaluate mouse mammary tumor virus-polyoma middle T-antigen (MMTV-PyMT) induced mammary tumorigenesis in the presence and absence of PKCβ. We utilize two model systems: one where PKCβ is deleted in both the epithelial and stromal compartments to test the global requirement for PKCβ on tumor formation, and second, where PKCβ is deleted only in the stromal compartment to test its role in the TME. MMTV-PyMT mice globally lacking PKCβ live longer and develop smaller tumors with decreased proliferation and decreased macrophage infiltration. Similarly, when PKCβ is null exclusively in the stroma, PyMT-driven B6 cells form smaller tumors with diminished collagen deposition. These experiments reveal for the first time a tumor promoting role for stromal PKCβ in MMTV-PyMT tumorigenesis. In corroboration with these results, PKCβ mRNA (Prkcb) is increased in fibroblasts isolated from MMTV-PyMT tumors. These data were confirmed in a breast cancer patient cohort. Combined these data suggest the continued investigation of PKCβ in the mammary TME is necessary to elucidate how to effectively target this signaling pathway in breast cancer.
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http://dx.doi.org/10.3389/fonc.2014.00087DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4006052PMC
May 2014

FOXC1 is enriched in the mammary luminal progenitor population, but is not necessary for mouse mammary ductal morphogenesis.

Biol Reprod 2013 Jul 11;89(1):10. Epub 2013 Jul 11.

Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.

Expression of FOXC1, a forkhead box transcription factor, correlates with the human basal-like breast cancer (BLBC) subtype, and functional analyses have revealed its importance for in vitro invasiveness of BLBC cells. Women diagnosed with this breast tumor subtype have a poorer outcome because of the lack of targeted therapies; thus, continued investigation of factors driving these tumors is critical to uncover novel therapeutic targets. Several processes that dictate normal mammary morphogenesis parallel cancer progression, and enforced expression of FOXC1 can induce a progenitor state in more-differentiated mammary epithelial cells. Consequently, evaluating how FOXC1 functions in the normal gland is critical to further understand BLBC biology. Although FOXC1 is well known to control normal development of a number of tissues, its role in the mammary gland has not yet been investigated. Herein, we describe FOXC1 expression patterning in the normal breast, where it is localized to the basal/myoepithelium, suggesting that FOXC1 would be required for normal development. However, mammary glands lacking Foxc1 have no overt defect in ductal outgrowth, alveologenesis, or lineage specification. Of significant interest, we found that expression of FOXC1 is enriched in the normal luminal progenitor population, which is the postulated cell of origin of BLBC. These results indicate that FOXC1 is unnecessary for mammary morphogenesis and that its role in BLBC likely involves processes that are unrelated to cell lineage specification.
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http://dx.doi.org/10.1095/biolreprod.113.108001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6322436PMC
July 2013

The forkhead box transcription factor FOXC1 promotes breast cancer invasion by inducing matrix metalloprotease 7 (MMP7) expression.

J Biol Chem 2012 Jul 29;287(29):24631-40. Epub 2012 May 29.

Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA.

Therapeutic options for treatment of basal-like breast cancers are limited and identification of molecular targets for novel therapies to treat this aggressive cancer is urgently needed. Recently, FOXC1, a forkhead box transcription factor, was identified as a functionally important biomarker of breast cancer aggressiveness and the basal-like breast cancer subtype. However, the mechanism through which FOXC1 controls aggressiveness of basal-like breast cancer remains to be elucidated. Here, we identify matrix metalloprotease 7 (MMP7) as a key downstream effector of FOXC1-mediated invasiveness. Expression of FOXC1 and MMP7 is significantly correlated in breast cancer samples and cell lines at both the mRNA and protein levels. Transient expression of FOXC1 in nontransformed mammary epithelial cell lines resulted in significantly increased expression of MMP7 and an MMP7-dependent increase in invasiveness. In reciprocal experiments, silencing endogenous FOXC1 in basal-like breast cancer cell lines resulted in decreased expression of MMP7 without decreased expression of other matrix metalloproteinases. We also demonstrate that elevated co-expression of FOXC1 and MMP7 is an independent predictor of patient outcome in multivariate analyses of two breast cancer patient cohorts. Together, our findings identify MMP7 as a novel mechanism through which FOXC1 may regulate the basal-like breast cancer invasive phenotype and the propensity of these cancers to metastasize. Furthermore, our findings demonstrate for the first time a correlation between MMP7 expression and basal-like breast cancers, suggesting that MMP7 may be a useful therapeutic target for treatment of this disease.
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http://dx.doi.org/10.1074/jbc.M112.375865DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3397891PMC
July 2012

Cloning and characterization of scon-3+, a new member of the Neurospora crassa sulfur regulatory system.

Eukaryot Cell 2002 Dec;1(6):875-83

Department of Biochemistry and Molecular Biology, Wright State University, Dayton, Ohio 45435, USA.

The sulfur regulatory system of Neurospora crassa consists of a group of sulfur-regulated structural genes (e.g., arylsulfatase) that are under coordinate control of the CYS3 positive regulator and sulfur controller (SCON) negative regulators. Here we report on the cloning of scon-3(+), which encodes a polypeptide of 171 amino acids and is a Skp1 family homolog. Repeat-induced point mutation of scon-3(+) resulted in a phenotype of constitutive expression of arylsulfatase, a phenotype consistent with other sulfur controller mutants. Northern analysis indicated that, unlike other members of the sulfur regulatory system, expression of scon-3(+) is not under the direct control of the CYS3 transcriptional activator. In particular, scon-3(+) mRNA was detectable under sulfur repressing or derepressing conditions in a Deltacys-3 mutant. In yeast, Skp1p and an F-box protein binding partner are core constituents of a class of E3 ubiquitin ligases known as SCF complexes. The N. crassa negative regulator SCON2 contains an F-box motif essential for the operation of the sulfur regulatory system and suggests a role for an SCF complex in the N. crassa sulfur regulatory system. A crucial set of experiments, by using a yeast two-hybrid approach with confirming coimmunoprecipitation assays, demonstrated that SCON3 interacts with SCON2 in a manner dependent upon the F-box motif of SCON2. The protein-protein interaction detected between SCON2 and SCON3 represents the initial demonstration in a filamentous fungus of functional interaction between putative core components of a SCF complex.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC138751PMC
http://dx.doi.org/10.1128/ec.1.6.875-883.2002DOI Listing
December 2002