@article {129163, title = {Methyltransferase-independent function of enhancer of zeste homologue 2 maintains tumorigenicity induced by human oncogenic papillomavirus and polyomavirus.}, journal = {Tumour Virus Res}, year = {2023}, month = {2023 May 25}, pages = {200264}, abstract = {

Merkel cell polyomavirus (MCV) and high-risk human papillomavirus (HPV) are human tumor viruses that cause Merkel cell carcinoma (MCC) and oropharyngeal squamous cell carcinoma (OSCC), respectively. HPV E7 and MCV large T (LT) oncoproteins target the retinoblastoma tumor suppressor protein (pRb) through the conserved LxCxE motif. We identified enhancer of zeste homolog 2 (EZH2) as a common host oncoprotein activated by both viral oncoproteins through the pRb binding motif. EZH2 is a catalytic subunit of the polycomb 2 (PRC2) complex that trimethylates histone H3 at lysine 27 (H3K27me3). In MCC tissues EZH2 was highly expressed, irrespective of MCV status. Loss-of-function studies revealed that viral HPV E6/E7 and T antigen expression are required for Ezh2 mRNA expression and that EZH2 is essential for HPV(+)OSCC and MCV(+)MCC cell growth. Furthermore, EZH2 protein degraders reduced cell viability efficiently and rapidly in HPV(+)OSCC and MCV(+)MCC cells, whereas EZH2 histone methyltransferase inhibitors did not affect cell proliferation or viability within the same treatment period. These results suggest that a methyltransferase-independent function of EZH2 contributes to tumorigenesis downstream of two viral oncoproteins, and that direct targeting of EZH2 protein expression could be a promising strategy for the inhibition of tumor growth in HPV(+)OSCC and MCV(+)MCC patients.

}, issn = {2666-6790}, doi = {10.1016/j.tvr.2023.200264}, author = {Khattri, Michelle and Amako, Yutaka and Gibbs, Julia R and Collura, Joseph L and Arora, Reety and Harold, Alexis and Li, Meng Yen and Harms, Paul W and Ezhkova, Elena and Shuda, Masahiro} } @article {74444, title = {DETECTing Merkel Cell Polyomavirus in Merkel Tumors.}, journal = {Front Mol Biosci}, volume = {7}, year = {2020}, month = {2020}, pages = {10}, abstract = {

Merkel cell carcinoma (MCC) is a rare, aggressive skin cancer caused either by Merkel cell polyomavirus (MCV) T antigen expression, post-integration (~80\% cases), or by UV-mediated DNA damage. Interestingly, overall survival of MCV-positive Merkel cell carcinoma patients is better, making this differential information of significant diagnostic and prognostic value. Also, MCV provides a direct target for therapy in MCC patients. Currently, the methods used for diagnosis of MCV in tumors are often discordant and unreliable. Here we used a guided molecular scissors based-DNA Endonuclease Targeted CRISPR Trans Reporter (DETECTR) technique to develop an molecular diagnostic tool for MCV-positive MCC. DETECTR couples recombinase polymerase based amplification of target MCV DNA with Cas12a mediated detection. CRISPR diagnostics couple specific detection followed by cutting of the pathogenic DNA by the Cas enzyme-gRNA complex, with non-specific cutting of ssDNA that provides a measurable visual cue. To detect MCV DNA in MCC, we designed Cas12a gRNAs targeting the MCV DNA and tested their targeting efficiency, and sensitivity using a fluorophore quencher labeled reporter assay. We show that MCV DETECTR system can detect MCV integrated in Merkel tumor rapidly, specifically and with femto-molar sensitivity. Our study is a preliminary, proof-of-principle analysis showing the use of CRISPR for MCV diagnosis. Further validation in human tumor samples is needed for its clinical use in the near future. This new system is promising and we hope it can be coupled with immunohistochemical studies to diagnose the viral status of MCC in clinics soon.

}, issn = {2296-889X}, doi = {10.3389/fmolb.2020.00010}, author = {Arora, Reety and Gupta, Komal and Vijaykumar, Anjali and Krishna, Sudhir} } @article {82354, title = {Merkel Cell Polyomavirus in Merkel Cell Carcinoma: Integration Sites and Involvement of the KMT2D Tumor Suppressor Gene.}, journal = {Viruses}, volume = {12}, year = {2020}, month = {2020 Aug 31}, abstract = {

Merkel cell carcinoma (MCC) is an uncommon, lethal cancer of the skin caused by either Merkel cell polyomavirus (MCPyV) or UV-linked mutations. MCPyV is found integrated into MCC tumor genomes, accompanied by truncation mutations that render the MCPyV large T antigen replication incompetent. We used the open access HPV Detector/Cancer-virus Detector tool to determine MCPyV integration sites in whole-exome sequencing data from five MCC cases, thereby adding to the limited published MCPyV integration site junction data. We also systematically reviewed published data on integration for MCPyV in the human genome, presenting a collation of 123 MCC cases and their linked chromosomal sites. We confirmed that there were no highly recurrent specific sites of integration. We found that chromosome 5 was most frequently involved in MCPyV integration and that integration sites were significantly enriched for genes with binding sites for oncogenic transcription factors such as LEF1 and ZEB1, suggesting the possibility of increased open chromatin in these gene sets. Additionally, in one case we found, for the first time, integration involving the tumor suppressor gene , adding to previous reports of rare MCPyV integration into host tumor suppressor genes in MCC.

}, issn = {1999-4915}, doi = {10.3390/v12090966}, author = {Arora, Reety and Choi, Jae Eun and Harms, Paul W and Chandrani, Pratik} } @article {51247, title = {Dual inhibition of MDM2 and MDM4 in virus-positive Merkel cell carcinoma enhances the p53 response.}, journal = {Proc Natl Acad Sci U S A}, volume = {116}, year = {2019}, month = {2019 Jan 15}, pages = {1027-1032}, abstract = {

Merkel cell polyomavirus (MCV) contributes to approximately 80\% of all Merkel cell carcinomas (MCCs), a highly aggressive neuroendocrine carcinoma of the skin. MCV-positive MCC expresses small T antigen (ST) and a truncated form of large T antigen (LT) and usually contains wild-type p53 (TP53) and RB (RB1). In contrast, virus-negative MCC contains inactivating mutations in TP53 and RB1. While the MCV-truncated LT can bind and inhibit RB, it does not bind p53. We report here that MCV LT binds to RB, leading to increased levels of ARF, an inhibitor of MDM2, and activation of p53. However, coexpression of ST reduced p53 activation. MCV ST recruits the MYC homologue MYCL (L-Myc) to the EP400 chromatin remodeler complex and transactivates specific target genes. We observed that depletion of EP400 in MCV-positive MCC cell lines led to increased p53 target gene expression. We suspected that the MCV ST-MYCL-EP400 complex could functionally inactivate p53, but the underlying mechanism was not known. Integrated ChIP and RNA-sequencing analysis following EP400 depletion identified MDM2 as well as CK1α, an activator of MDM4, as target genes of the ST-MYCL-EP400 complex. In addition, MCV-positive MCC cells expressed high levels of MDM4. Combining MDM2 inhibitors with lenalidomide targeting CK1α or an MDM4 inhibitor caused synergistic activation of p53, leading to an apoptotic response in MCV-positive MCC cells and MCC-derived xenografts in mice. These results support dual targeting of MDM2 and MDM4 in virus-positive MCC and other p53 wild-type tumors.

}, issn = {1091-6490}, doi = {10.1073/pnas.1818798116}, author = {Park, Donglim Esther and Cheng, Jingwei and Berrios, Christian and Montero, Joan and Cort{\'e}s-Cros, Marta and Ferretti, St{\'e}phane and Arora, Reety and Tillgren, Michelle L and Gokhale, Prafulla C and DeCaprio, James A} } @article {74436, title = {MCV Truncated Large T antigen interacts with BRD4 in tumors}, journal = {Matters}, year = {2019}, month = {01/2019}, abstract = {

Among Polyomaviridae family of viruses, Merkel Cell Polyomavirus (MCV) is the only human polyomavirus with convincing data supporting its classification as a direct causative agent of a human skin malignancy, Merkel Cell Carcinoma. Oncogenic transformation by MCV requires the integration of the viral genome into the human genome, truncation of the large T antigen (LT) to render the viral genome replication deficient and expression of small T antigen oncoprotein. The chromatin binding protein BRD4, was recently shown to transcriptionally regulate the expression of virus oncoproteins, thereby enhancing the tumorigenesis of virus-associated cancers, such as HPV associated cervical cancer. Previous work by Wang et al. revealed that BRD4 interacts with MCV full length LT during viral replication. In this study, we demonstrated that MCV truncated tumor LT antigen also interacts with BRD4 protein. We showed that the MCV tumor LT antigen and BRD4 protein complex co-localizes within the nucleus. Furthermore, we tested whether BRD4 protein transcriptionally regulates MCV Non Coding Control Region (NCCR), where we found that though full length LT and sT together, along with the BRD4 protein showed enhanced transcriptional activity whereas tumor truncated LT did not. These findings on the interactions of the MCV tumor truncated LT antigen with the BRD4 protein add to existing knowledge about interactions with LT and its role in tumorigenesis, and assist in efforts to more precisely define new therapy targets for this disease.

}, doi = {10.19185/matters.201811000004}, author = {Arora, Reety and Vats, A and Chimankar, V} } @article {66090, title = {Merkel cell polyomavirus is implicated in a subset of Merkel cell carcinomas, in the Indian subcontinent.}, journal = {Microb Pathog}, year = {2019}, month = {2019 Oct 07}, pages = {103778}, abstract = {

Merkel cell carcinoma is a rare, lethal cancer histopathologically composed of cells showing similarity with mechanoreceptor Merkel cells. Merkel cell tumors manifest in two distinct forms. While a virus called Merkel cell polyomavirus is involved in the pathogenesis of one form of Merkel tumor, the other is driven by ultraviolet (UV)-linked mutations. In this study we investigated 18 cases, from the Indian population, of Merkel cell carcinoma for immunohistochemical (IHC) expression of Merkel cell polyomavirus (MCV) T antigen, including 12 cases tested by PCR, to identify viral etiopathology. We tested the tumors with two sensitive antibodies (CM2B4 and Ab3), targeting the viral large T antigen protein and with PCR primers targeting the N terminus of T antigen. Overall, we observed 38.8\% (7/18) tumors displaying positive IHC expression of Merkel cell polyomavirus T antigen and 25\% (3/12) tumors showing positive results, by both, immunohistochemistry and PCR. This constitutes the first report from India showing implication of MCV in Merkel cell carcinomas. Moreover, this is one of the larger series of Merkel cell carcinomas, tested for MCV, by both immunohistochemistry and PCR, in this part of the world. These results further indicate that a slightly more number of such cases in India are likely to be caused by UV-linked damage, as opposed to Merkel cell polyomavirus mediated tumorigenesis, which is definitely implicated in a subset of cases.

}, issn = {1096-1208}, doi = {10.1016/j.micpath.2019.103778}, author = {Arora, Reety and Rekhi, Bharat and Chandrani, Pratik and Krishna, Sudhir and Dutt, Amit} } @article {53190, title = {A SUV39H1-low chromatin state characterises and promotes migratory properties of cervical cancer cells.}, journal = {Exp Cell Res}, year = {2019}, month = {2019 Feb 14}, abstract = {

Metastatic progression is a major cause of mortality in cervical cancers, but factors regulating migratory and pre-metastatic cell populations remain poorly understood. Here, we sought to assess whether a SUV39H1-low chromatin state promotes migratory cell populations in cervical cancers, using meta-analysis of data from The Cancer Genome Atlas (TCGA), immunohistochemistry, genomics and functional assays. Cervical cancer cells sorted based on migratory ability in vitro have low levels of SUV39H1 protein, and SUV39H1 knockdown in vitro enhanced cervical cancer cell migration. Further, TCGA SUV39H1-low tumours correlated with poor clinical outcomes and showed gene expression signatures of cell migration. SUV39H1 expression was examined within biopsies, and SUV39H1 cells within tumours also demonstrated migratory features. Next, to understand genome scale transcriptional and chromatin changes in migratory populations, cell populations sorted based on migration in vitro were examined using RNA-Seq, along with ChIP-Seq for H3K9me3, the histone mark associated with SUV39H1. Migrated populations showed SUV39H1-linked migratory gene expression signatures, along with broad depletion of H3K9me3 across gene promoters. We show for the first time that a SUV39H1-low chromatin state associates with, and promotes, migratory populations in cervical cancers. Our results posit SUV39H1-low cells as key populations for prognosis estimation and as targets for novel therapies.

}, issn = {1090-2422}, doi = {10.1016/j.yexcr.2019.02.010}, author = {Rodrigues, Calvin and Pattabiraman, Chitra and Vijaykumar, Anjali and Arora, Reety and Narayana, Suma Mysore and Kumar, Rekha V and Notani, Dimple and Varga-Weisz, Patrick and Krishna, Sudhir} }