Publications by authors named "Hui-Zi Chen"

24 Publications

  • Page 1 of 1

Fibroblast growth factor receptors in cancer: genetic alterations, diagnostics, therapeutic targets and mechanisms of resistance.

Br J Cancer 2021 Mar 3;124(5):880-892. Epub 2020 Dec 3.

Department of Internal Medicine, The Ohio State University Comprehensive Cancer Center, Columbus, OH, USA.

Fibroblast growth factor receptors (FGFRs) are aberrantly activated through single-nucleotide variants, gene fusions and copy number amplifications in 5-10% of all human cancers, although this frequency increases to 10-30% in urothelial carcinoma and intrahepatic cholangiocarcinoma. We begin this review by highlighting the diversity of FGFR genomic alterations identified in human cancers and the current challenges associated with the development of clinical-grade molecular diagnostic tests to accurately detect these alterations in the tissue and blood of patients. The past decade has seen significant advancements in the development of FGFR-targeted therapies, which include selective, non-selective and covalent small-molecule inhibitors, as well as monoclonal antibodies against the receptors. We describe the expanding landscape of anti-FGFR therapies that are being assessed in early phase and randomised controlled clinical trials, such as erdafitinib and pemigatinib, which are approved by the Food and Drug Administration for the treatment of FGFR3-mutated urothelial carcinoma and FGFR2-fusion cholangiocarcinoma, respectively. However, despite initial sensitivity to FGFR inhibition, acquired drug resistance leading to cancer progression develops in most patients. This phenomenon underscores the need to clearly delineate tumour-intrinsic and tumour-extrinsic mechanisms of resistance to facilitate the development of second-generation FGFR inhibitors and novel treatment strategies beyond progression on targeted therapy.
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http://dx.doi.org/10.1038/s41416-020-01157-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7921129PMC
March 2021

Characterization of Clonal Evolution in Microsatellite Unstable Metastatic Cancers through Multiregional Tumor Sequencing.

Mol Cancer Res 2021 Mar 23;19(3):465-474. Epub 2020 Nov 23.

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

Microsatellites are short, repetitive segments of DNA, which are dysregulated in mismatch repair-deficient (MMRd) tumors resulting in microsatellite instability (MSI). MSI has been identified in many human cancer types with varying incidence, and microsatellite instability-high (MSI-H) tumors often exhibit increased sensitivity to immune-enhancing therapies such as PD-1/PD-L1 inhibition. Next-generation sequencing (NGS) has permitted advancements in MSI detection, and recent computational advances have enabled characterization of tumor heterogeneity via NGS. However, the evolution and heterogeneity of microsatellite changes in MSI-positive tumors remains poorly described. We determined MSI status in 6 patients using our previously published algorithm, MANTIS, and inferred subclonal composition and phylogeny with Canopy and SuperFreq. We developed a simulated annealing-based method to characterize microsatellite length distributions in specific subclones and assessed the evolution of MSI in the context of tumor heterogeneity. We identified three to eight tumor subclones per patient, and each subclone exhibited MMRd-associated base substitution signatures. We noted that microsatellites tend to shorten over time, and that MMRd fosters heterogeneity by introducing novel mutations throughout the disease course. Some microsatellites are altered among all subclones in a patient, whereas other loci are only altered in particular subclones corresponding to subclonal phylogenetic relationships. Overall, our results indicate that MMRd is a substantial driver of heterogeneity, leading to both MSI and subclonal divergence. IMPLICATIONS: We leveraged subclonal inference to assess clonal evolution based on somatic mutations and microsatellites, which provides insight into MMRd as a dynamic mutagenic process in MSI-H malignancies.
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http://dx.doi.org/10.1158/1541-7786.MCR-19-0955DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7939074PMC
March 2021

Efficacy of FGFR Inhibitors and Combination Therapies for Acquired Resistance in FGFR2-Fusion Cholangiocarcinoma.

Mol Cancer Ther 2020 03 7;19(3):847-857. Epub 2020 Jan 7.

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

The fibroblast growth factor receptor (FGFR) signaling pathway is aberrantly activated in approximately 15% to 20% of patients with intrahepatic cholangiocarcinoma. Currently, several FGFR kinase inhibitors are being assessed in clinical trials for patients with FGFR-altered cholangiocarcinoma. Despite evidence of initial responses and disease control, virtually all patients eventually develop acquired resistance. Thus, there is a critical need for the development of innovative therapeutic strategies to overcome acquired drug resistance. Here, we present findings from a patient with FGFR2-altered metastatic cholangiocarcinoma who enrolled in a phase II clinical trial of the FGFR inhibitor, infigratinib (BGJ398). Treatment was initially effective as demonstrated by imaging and tumor marker response; however, after 8 months on trial, the patient exhibited tumor regrowth and disease progression. Targeted sequencing of tumor DNA after disease progression revealed the kinase domain p.E565A and p.L617M single-nucleotide variants (SNV) hypothesized to drive acquired resistance to infigratinib. The sensitivities of these SNVs, which were detected post-infigratinib therapy, were extended to include clinically relevant FGFR inhibitors, including AZD4547, erdafitinib (JNJ-42756493), dovitinib, ponatinib, and TAS120, and were evaluated Through a proteomics approach, we identified upregulation of the PI3K/AKT/mTOR signaling pathway in cells harboring the p.E565A mutation and demonstrated that combination therapy strategies with FGFR and mTOR inhibitors may be used to overcome resistance to FGFR inhibition, specific to infigratinib. Collectively, these studies support the development of novel combination therapeutic strategies in addition to the next generation of FGFR inhibitors to overcome acquired resistance in patients.
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http://dx.doi.org/10.1158/1535-7163.MCT-19-0631DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7359896PMC
March 2020

Detection of Microsatellite Instability Biomarkers via Next-Generation Sequencing.

Methods Mol Biol 2020 ;2055:119-132

Division of Medical Oncology, Department of Internal Medicine, Comprehensive Cancer Center, The Ohio State University, Columbus, OH, USA.

A high level of microsatellite instability (MSI-H+) is an emerging predictive and prognostic biomarker for immunotherapy response in cancer. Recently, MSI-H+ has been detected in a variety of cancer types, in addition to the classical cancers associated with Lynch Syndrome. Clinical testing for MSI-H+ is currently performed primarily through traditional polymerase chain reaction (PCR) or immunohistochemistry (IHC) assays. However, next-generation sequencing (NGS)-based approaches have been developed which have multiple advantages over traditional assays. For instance, NGS has the ability to interrogate thousands of microsatellite loci compared with just 5-7 loci that are detected by PCR. In this chapter, we detail the biochemical and computational steps to detect MSI-H+ from analysis of paired tumor and normal samples through NGS. We begin with DNA extraction, describe sequencing library preparation and quality control (QC), and outline the bioinformatics steps necessary for sequence alignment, preprocessing, and MSI-H+ detection using the software tool MANTIS. This workflow is intended to facilitate more widespread usage and adaptation of NGS-powered MSI detection, which can be eventually standardized for routine clinical testing.
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http://dx.doi.org/10.1007/978-1-4939-9773-2_5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7010320PMC
November 2020

Tumor heterogeneity and acquired drug resistance in FGFR2-fusion-positive cholangiocarcinoma through rapid research autopsy.

Cold Spring Harb Mol Case Stud 2019 08 1;5(4). Epub 2019 Aug 1.

Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio 43210, USA.

Cholangiocarcinoma is a highly aggressive and lethal malignancy, with limited treatment options available. Recently, FGFR inhibitors have been developed and utilized in FGFR-mutant cholangiocarcinoma; however, resistance often develops and the genomic determinants of resistance are not fully characterized. We completed whole-exome sequencing (WES) of 11 unique tumor samples obtained from a rapid research autopsy on a patient with FGFR-fusion-positive cholangiocarcinoma who initially responded to the pan-FGFR inhibitor, INCB054828. In vitro studies were carried out to characterize the novel FGFR alteration and secondary mutation identified. Multisite WES and analysis of tumor heterogeneity through subclonal inference identified four genetically distinct cancer cell populations, two of which were only observed after treatment. Additionally, WES revealed an N549H mutation hypothesized to confer resistance to the FGFR inhibitor INCB054828 in a single tumor sample. This hypothesis was corroborated with in vitro cell-based studies in which cells expressing fusion were sensitive to INCB054828 (IC value of 10.16 nM), whereas cells with the addition of the N549H mutation were resistant to INCB054828 (IC value of 1527.57 nM). Furthermore, the N549H secondary mutation displayed cross-resistance to other selective FGFR inhibitors, but remained sensitive to the nonselective inhibitor, ponatinib. Rapid research autopsy has the potential to provide unprecedented insights into the clonal evolution of cancer throughout the course of the disease. In this study, we demonstrate the emergence of a drug resistance mutation and characterize the evolution of tumor subclones within a cholangiocarcinoma disease course.
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http://dx.doi.org/10.1101/mcs.a004002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6672025PMC
August 2019

Characterization of a KLK2-FGFR2 fusion gene in two cases of metastatic prostate cancer.

Prostate Cancer Prostatic Dis 2019 12 1;22(4):624-632. Epub 2019 May 1.

Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA.

Background: The fibroblast growth factor receptor (FGFR) signaling pathway is activated in multiple tumor types through gene amplifications, single base substitutions, or gene fusions. Multiple small molecule kinase inhibitors targeting FGFR are currently being evaluated in clinical trials for patients with FGFR chromosomal translocations. Patients with novel gene fusions involving FGFR may represent candidates for kinase inhibitors.

Methods: A targeted RNA-sequencing assay identified a KLK2-FGFR2 fusion gene in two patients with metastatic prostate cancer. NIH3T3 cells were transduced to express the KLK2-FGFR2 fusion. Migration assays, Western blots, and drug sensitivity assays were performed to functionally characterize the fusion.

Results: Expression of the KLK2-FGFR2 fusion protein in NIH3T3 cells induced a profound morphological change promoting enhanced migration and activation of downstream proteins in FGFR signaling pathways. The KLK2-FGFR2 fusion protein was determined to be highly sensitive to the selective FGFR inhibitors AZD-4547, BGJ398, JNJ-42756943, the irreversible inhibitor TAS-120, and the non-selective inhibitor Ponatinib. The KLK2-FGFR2 fusion did not exhibit sensitivity to the non-selective inhibitor Dovitinib.

Conclusions: Importantly, the KLK2-FGFR2 fusion represents a novel target for precision therapies and should be screened for in men with prostate cancer.
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http://dx.doi.org/10.1038/s41391-019-0145-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6824932PMC
December 2019

Genomic characterization of metastatic ultra-hypermutated interdigitating dendritic cell sarcoma through rapid research autopsy.

Oncotarget 2019 Jan 8;10(3):277-288. Epub 2019 Jan 8.

Department of Internal Medicine, Division of Medical Oncology, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio, USA.

Interdigitating dendritic cell sarcoma (IDCS) is an extremely rare cancer of dendritic cell origin that lacks a standardized treatment approach. Here, we performed genomic characterization of metastatic IDCS through whole exome sequencing (WES) of tumor tissues procured from a patient who underwent research autopsy. WES was also performed on a treatment-naïve tumor biopsy sample obtained from prior surgical resection. Our analyses revealed ultra-hypermutation, defined as >100 mutations per megabase, in this patient's cancer, which was further characterized by the presence of three distinct mutational signatures including UV radiation and APOBEC signatures. To characterize clonal heterogeneity, we used the bioinformatics tool Canopy to leverage single nucleotide and copy number variants to catalog six subclones across various metastatic tumors. Truncal alterations, defined as being present in all clonal tumor cell populations, in this patient's cancer include point mutations in and and amplifications of and , which are likely driver mutations. In summary, we have performed genomic characterization evaluating tumor mutational burden (TMB) and heterogeneity in a patient with metastatic IDCS. Despite ultra-hypermutation, this patient's cancer was not responsive to treatment with PD-1 inhibition. Our results underscore the importance of characterizing clonal heterogeneity in TMB-high cancers.
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http://dx.doi.org/10.18632/oncotarget.26352DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6349455PMC
January 2019

Rapid Research Autopsy: Piecing the Puzzle of Tumor Heterogeneity.

Trends Cancer 2019 01 17;5(1):1-5. Epub 2018 Dec 17.

Department of Internal Medicine, Division of Medical Oncology, The Ohio State University, Columbus, OH, USA; Comprehensive Cancer Center, The Ohio State University, Columbus, OH, USA. Electronic address:

Tumor heterogeneity decreases the effectiveness of anticancer therapies and is an important topic in translational cancer research, given its relevance in clinical oncology. Here, we discuss how rapid research autopsy of cancer patients can elucidate heterogeneity-associated processes including cancer evolution and acquired therapeutic resistance. In practice, rapid research autopsy is performed shortly after a patient's passing to procure multiple metastatic tumor samples for genomic studies through next-generation sequencing and development of patient-derived xenografts or organoids. Mechanistic insights gained from research autopsy studies of cancer patients can help identify new targets for therapeutic intervention. Finally, the success of research autopsy programs is bolstered by collaboration across different medical and scientific disciplines in addition to support from patients and families.
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http://dx.doi.org/10.1016/j.trecan.2018.11.004DOI Listing
January 2019

Metastatic Calcinosis Cutis Associated With a Selective FGFR Inhibitor.

JAMA Dermatol 2019 Jan;155(1):122-123

Division of Dermatology, Department of Medicine, The Ohio State University, Columbus.

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http://dx.doi.org/10.1001/jamadermatol.2018.4070DOI Listing
January 2019

Implementing precision cancer medicine in the genomic era.

Semin Cancer Biol 2019 04 30;55:16-27. Epub 2018 May 30.

Department of Internal Medicine, Division of Medical Oncology, Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, United States. Electronic address:

The utilization of genomic data to direct treatment for cancer patients represents the central tenet in precision oncology, in which a patient is matched to a specific drug or therapy based on the genetic drivers detected in his or her tumor rather than the tumor's histologic classification. The expected but not always realized outcomes of molecularly matched therapies include increased response rates, more durable responses, deeper responses, and decreased number of therapy-related side effects. In this review, we will discuss different facets of utilizing genomic data to direct the increasingly complex care of cancer patients. We discuss the enlarging compendium of actionable genomic alterations and the development of novel molecular diagnostic assays for clinical application. Finally, we present an overview of the growing number of genomics-driven clinical trials and conclude with a discussion of future challenges in the implementation of precision oncology.
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http://dx.doi.org/10.1016/j.semcancer.2018.05.009DOI Listing
April 2019

Tumor spread through air space (STAS) is an important predictor of clinical outcome in stage IA lung adenocarcinoma.

J Thorac Dis 2017 Aug;9(8):2283-2285

The James Cancer Hospital and Solove Research Institute, Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210, USA.

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http://dx.doi.org/10.21037/jtd.2017.07.69DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5594112PMC
August 2017

Landscape of Microsatellite Instability Across 39 Cancer Types.

JCO Precis Oncol 2017 3;2017. Epub 2017 Oct 3.

The Ohio State University, Columbus, OH.

Purpose: Microsatellite instability (MSI) is a pattern of hypermutation that occurs at genomic microsatellites and is caused by defects in the mismatch repair system. Mismatch repair deficiency that leads to MSI has been well described in several types of human cancer, most frequently in colorectal, endometrial, and gastric adenocarcinomas. MSI is known to be both predictive and prognostic, especially in colorectal cancer; however, current clinical guidelines only recommend MSI testing for colorectal and endometrial cancers. Therefore, less is known about the prevalence and extent of MSI among other types of cancer.

Methods: Using our recently published MSI-calling software, MANTIS, we analyzed whole-exome data from 11,139 tumor-normal pairs from The Cancer Genome Atlas and Therapeutically Applicable Research to Generate Effective Treatments projects and external data sources across 39 cancer types. Within a subset of these cancer types, we assessed mutation burden, mutational signatures, and somatic variants associated with MSI.

Results: We identified MSI in 3.8% of all cancers assessed-present in 27 of tumor types-most notably adrenocortical carcinoma (ACC), cervical cancer (CESC), and mesothelioma, in which MSI has not yet been well described. In addition, MSI-high ACC and CESC tumors were observed to have a higher average mutational burden than microsatellite-stable ACC and CESC tumors.

Conclusion: We provide evidence of as-yet-unappreciated MSI in several types of cancer. These findings support an expanded role for clinical MSI testing across multiple cancer types as patients with MSI-positive tumors are predicted to benefit from novel immunotherapies in clinical trials.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5972025PMC
http://dx.doi.org/10.1200/PO.17.00073DOI Listing
October 2017

E2f8 mediates tumor suppression in postnatal liver development.

J Clin Invest 2016 08 25;126(8):2955-69. Epub 2016 Jul 25.

E2F-mediated transcriptional repression of cell cycle-dependent gene expression is critical for the control of cellular proliferation, survival, and development. E2F signaling also interacts with transcriptional programs that are downstream of genetic predictors for cancer development, including hepatocellular carcinoma (HCC). Here, we evaluated the function of the atypical repressor genes E2f7 and E2f8 in adult liver physiology. Using several loss-of-function alleles in mice, we determined that combined deletion of E2f7 and E2f8 in hepatocytes leads to HCC. Temporal-specific ablation strategies revealed that E2f8's tumor suppressor role is critical during the first 2 weeks of life, which correspond to a highly proliferative stage of postnatal liver development. Disruption of E2F8's DNA binding activity phenocopied the effects of an E2f8 null allele and led to HCC. Finally, a profile of chromatin occupancy and gene expression in young and tumor-bearing mice identified a set of shared targets for E2F7 and E2F8 whose increased expression during early postnatal liver development is associated with HCC progression in mice. Increased expression of E2F8-specific target genes was also observed in human liver biopsies from HCC patients compared to healthy patients. In summary, these studies suggest that E2F8-mediated transcriptional repression is a critical tumor suppressor mechanism during postnatal liver development.
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http://dx.doi.org/10.1172/JCI85506DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4966321PMC
August 2016

Canonical and atypical E2Fs regulate the mammalian endocycle.

Nat Cell Biol 2012 Nov 14;14(11):1192-202. Epub 2012 Oct 14.

Solid Tumor Biology Program, Department of Molecular Virology, Immunology and Medical Genetics, Department of Molecular Genetics, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio 43210, USA.

The endocycle is a variant cell cycle consisting of successive DNA synthesis and gap phases that yield highly polyploid cells. Although essential for metazoan development, relatively little is known about its control or physiologic role in mammals. Using lineage-specific cre mice we identified two opposing arms of the E2F program, one driven by canonical transcription activation (E2F1, E2F2 and E2F3) and the other by atypical repression (E2F7 and E2F8), that converge on the regulation of endocycles in vivo. Ablation of canonical activators in the two endocycling tissues of mammals, trophoblast giant cells in the placenta and hepatocytes in the liver, augmented genome ploidy, whereas ablation of atypical repressors diminished ploidy. These two antagonistic arms coordinate the expression of a unique G2/M transcriptional program that is critical for mitosis, karyokinesis and cytokinesis. These results provide in vivo evidence for a direct role of E2F family members in regulating non-traditional cell cycles in mammals.
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http://dx.doi.org/10.1038/ncb2595DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3616487PMC
November 2012

Atypical E2F repressors and activators coordinate placental development.

Dev Cell 2012 Apr;22(4):849-62

Solid Tumor Biology Program, Department of Molecular Virology, Immunology and Medical Genetics, Human Cancer Genetics Program, Comprehensive Cancer Center, College of Medicine and Public Health, The Ohio State University, Columbus, OH 43210, USA.

The evolutionarily ancient arm of the E2f family of transcription factors consisting of the two atypical members E2f7 and E2f8 is essential for murine embryonic development. However, the critical tissues, cellular processes, and molecular pathways regulated by these two factors remain unknown. Using a series of fetal and placental lineage-specific cre mice, we show that E2F7/E2F8 functions in extraembryonic trophoblast lineages are both necessary and sufficient to carry fetuses to term. Expression profiling and biochemical approaches exposed the canonical E2F3a activator as a key family member that antagonizes E2F7/E2F8 functions. Remarkably, the concomitant loss of E2f3a normalized placental gene expression programs, corrected placental defects, and fostered the survival of E2f7/E2f8-deficient embryos to birth. In summary, we identified a placental transcriptional network tightly coordinated by activation and repression through two distinct arms of the E2F family that is essential for extraembryonic cell proliferation, placental development, and fetal viability.
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http://dx.doi.org/10.1016/j.devcel.2012.01.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3483796PMC
April 2012

Cell proliferation in the absence of E2F1-3.

Dev Biol 2011 Mar 23;351(1):35-45. Epub 2010 Dec 23.

Department of Molecular Virology, Immunology and Medical Genetics, Comprehensive Cancer Center, College of Medicine, The Ohio State University, Columbus, OH 43210, USA.

E2F transcription factors regulate the progression of the cell cycle by repression or transactivation of genes that encode cyclins, cyclin dependent kinases, checkpoint regulators, and replication proteins. Although some E2F functions are independent of the Retinoblastoma tumor suppressor (Rb) and related family members, p107 and p130, much of E2F-mediated repression of S phase entry is dependent upon Rb. We previously showed in cultured mouse embryonic fibroblasts that concomitant loss of three E2F activators with overlapping functions (E2F1, E2F2, and E2F3) triggered the p53-p21(Cip1) response and caused cell cycle arrest. Here we report on a dramatic difference in the requirement for E2F during development and in cultured cells by showing that cell cycle entry occurs normally in E2f1-3 triply-deficient epithelial stem cells and progenitors of the developing lens. Sixteen days after birth, however, massive apoptosis in differentiating epithelium leads to a collapse of the entire eye. Prior to this collapse, we find that expression of cell cycle-regulated genes in E2F-deficient lenses is aberrantly high. In a second set of experiments, we demonstrate that E2F3 ablation alone does not cause abnormalities in lens development but rescues phenotypic defects caused by loss of Rb, a binding partner of E2F known to recruit histone deacetylases, SWI/SNF and CtBP-polycomb complexes, methyltransferases, and other co-repressors to gene promoters. Together, these data implicate E2F1-3 in mediating transcriptional repression by Rb during cell cycle exit and point to a critical role for their repressive functions in cell survival.
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http://dx.doi.org/10.1016/j.ydbio.2010.12.025DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3868453PMC
March 2011

Allele-specific tumor spectrum in pten knockin mice.

Proc Natl Acad Sci U S A 2010 Mar 1;107(11):5142-7. Epub 2010 Mar 1.

Department of Molecular Genetics, College of Biological Sciences, Comprehensive Cancer Center, Ohio State University, Columbus, OH 43210, USA.

Germline mutations in the tumor suppressor gene PTEN (phosphatase and tensin homology deleted on chromosome 10) cause Cowden and Bannayan-Riley-Ruvalcaba (BRR) syndromes, two dominantly inherited disorders characterized by mental retardation, multiple hamartomas, and variable cancer risk. Here, we modeled three sentinel mutant alleles of PTEN identified in patients with Cowden syndrome and show that the nonsense Pten(4-5) and missense Pten(C124R) and Pten(G129E) alleles lacking lipid phosphatase activity cause similar developmental abnormalities but distinct tumor spectra with varying severity and age of onset. Allele-specific differences may be accounted for by loss of function for Pten(4-5), hypomorphic function for Pten(C124R), and gain of function for Pten(G129E). These data demonstrate that the variable tumor phenotypes observed in patients with Cowden and BRR syndromes can be attributed to specific mutations in PTEN that alter protein function through distinct mechanisms.
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http://dx.doi.org/10.1073/pnas.0912524107DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2841921PMC
March 2010

E2f1-3 switch from activators in progenitor cells to repressors in differentiating cells.

Nature 2009 Dec;462(7275):930-4

Department of Molecular Virology, Immunology and Medical Genetics, College of Medicine, The Ohio State University, Columbus, Ohio 43210, USA.

In the established model of mammalian cell cycle control, the retinoblastoma protein (Rb) functions to restrict cells from entering S phase by binding and sequestering E2f activators (E2f1, E2f2 and E2f3), which are invariably portrayed as the ultimate effectors of a transcriptional program that commit cells to enter and progress through S phase. Using a panel of tissue-specific cre-transgenic mice and conditional E2f alleles we examined the effects of E2f1, E2f2 and E2f3 triple deficiency in murine embryonic stem cells, embryos and small intestines. We show that in normal dividing progenitor cells E2f1-3 function as transcriptional activators, but contrary to the current view, are dispensable for cell division and instead are necessary for cell survival. In differentiating cells E2f1-3 function in a complex with Rb as repressors to silence E2f targets and facilitate exit from the cell cycle. The inactivation of Rb in differentiating cells resulted in a switch of E2f1-3 from repressors to activators, leading to the superactivation of E2f responsive targets and ectopic cell divisions. Loss of E2f1-3 completely suppressed these phenotypes caused by Rb deficiency. This work contextualizes the activator versus repressor functions of E2f1-3 in vivo, revealing distinct roles in dividing versus differentiating cells and in normal versus cancer-like cell cycles.
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http://dx.doi.org/10.1038/nature08677DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2806193PMC
December 2009

E2F3 is a mediator of DNA damage-induced apoptosis.

Mol Cell Biol 2010 Jan 16;30(2):524-36. Epub 2009 Nov 16.

Department of Biochemistry, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216, USA.

The E2F transcription factors have emerged as critical apoptotic effectors. Herein we report that the E2F family member E2F3a can be induced by DNA damage through transcriptional and posttranslational mechanisms. We demonstrate that the posttranslational induction of human E2F3a is dependent on the checkpoint kinases. Moreover, we show that human E2F3a is a substrate for the checkpoint kinases (chk kinases) and that mutation of the chk phosphorylation site eliminates the DNA damage inducibility of the protein. Furthermore, we demonstrate that E2F1 and E2F2 are transcriptionally induced by DNA damage in an E2f3-dependent manner. Finally, using both in vitro and in vivo approaches, we establish that E2f3 is required for DNA damage-induced apoptosis. Thus, our data reveal the novel ability of E2f3 to function as a master regulator of the DNA damage response.
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http://dx.doi.org/10.1128/MCB.00938-09DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2798461PMC
January 2010

Emerging roles of E2Fs in cancer: an exit from cell cycle control.

Nat Rev Cancer 2009 Nov;9(11):785-97

Human Cancer Genetics Program, Department of Molecular Virology, Immunology and Medical Genetics and Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210, USA.

Mutations of the retinoblastoma tumour suppressor gene (RB1) or components regulating the RB pathway have been identified in almost every human malignancy. The E2F transcription factors function in cell cycle control and are intimately regulated by RB. Studies of model organisms have revealed conserved functions for E2Fs during development, suggesting that the cancer-related proliferative roles of E2F family members represent a recent evolutionary adaptation. However, given that some human tumours have concurrent RB1 inactivation and E2F amplification and overexpression, we propose that there are alternative tumour-promoting activities for the E2F family, which are independent of cell cycle regulation.
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http://dx.doi.org/10.1038/nrc2696DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3616489PMC
November 2009

Synergistic function of E2F7 and E2F8 is essential for cell survival and embryonic development.

Dev Cell 2008 Jan;14(1):62-75

Department of Molecular Virology, The Ohio State University, Columbus, OH 43210, USA.

The E2f7 and E2f8 family members are thought to function as transcriptional repressors important for the control of cell proliferation. Here, we have analyzed the consequences of inactivating E2f7 and E2f8 in mice and show that their individual loss had no significant effect on development. Their combined ablation, however, resulted in massive apoptosis and dilation of blood vessels, culminating in lethality by embryonic day E11.5. A deficiency in E2f7 and E2f8 led to an increase in E2f1 and p53, as well as in many stress-related genes. Homo- and heterodimers of E2F7 and E2F8 were found on target promoters, including E2f1. Importantly, loss of either E2f1 or p53 suppressed the massive apoptosis in double-mutant embryos. These results identify E2F7 and E2F8 as a unique repressive arm of the E2F transcriptional network that is critical for embryonic development and control of the E2F1-p53 apoptotic axis.
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http://dx.doi.org/10.1016/j.devcel.2007.10.017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2253677PMC
January 2008

Activation of the Nrf2/antioxidant response pathway increases IL-8 expression.

Eur J Immunol 2005 Nov;35(11):3258-67

Department of Internal Medicine, The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University College of Medicine and Public Health, Columbus, OH, USA.

Oxidant stress can initiate or enhance inflammatory responses during tissue injury, possibly through activation of redox-sensitive chemokines. Because the transcription factor Nrf2 (NF-E2-related factor 2) is responsive to oxidative stress, and induces expression of cytoprotective and antioxidant genes that attenuate tissue injury, we postulated that Nrf2 may also regulate chemokine expression. To test this hypothesis, Nrf2 expression was directly increased in primary human kidney mesangial cells and aortic endothelial cells, or cell lines with an adenoviral construct, and the effects on the pro-inflammatory chemokine interleukin-8 (IL-8) were assessed. Nrf2 expression significantly increased IL-8 mRNA levels and protein secretion. Nrf2 caused only a weak induction of IL-8 transcription, but significantly increased the half-life of IL-8 mRNA. These data demonstrate that activation of the Nrf2/antioxidant response pathway induces expression of IL-8. The dominant mechanism of Nrf2-mediated IL-8 induction is through mRNA stabilization. Considering the evidence that Nrf2 activation is mainly cytoprotective, these observations raise the possibility that under certain circumstances IL-8 may serve an anti-inflammatory role and thereby contribute to the resolution of tissue injury.
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http://dx.doi.org/10.1002/eji.200526116DOI Listing
November 2005

Unexpected sensitivity of synthetic Renilla luciferase control vectors to treatment with a cyclopentenone prostaglandin.

Biotechniques 2003 Dec;35(6):1144-6, 1148

Ohio State University College of Medicine and Public Health, Columbus, OH, USA.

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http://dx.doi.org/10.2144/03356bm04DOI Listing
December 2003