Merkel cell carcinoma (MCC) is a neuroectodermal, AIDS-related cancer suspected to have a viral etiology. MCC is 13 times more common than expected among AIDS patients and occurs in post-transplant and other immunosuppressed patient populations. While rare, it is the most aggressive skin cancer and only 50% of patients with advanced disease survive 9 months or longer. There are no early detection markers and it is frequently misdiagnosed with other small round cell tumors. We identified a novel polyomavirus in MCC using digital transcriptome subtraction (DTS). This agent, Merkel carcinoma polyomavirus (MCPyV), is most closely related to African green monkey lymphotropic polyomavirus (LPyV). Between 15-30% of persons have antibodies to LPyV, which has led investigators to speculate on the existence of a closely related but undiscovered human virus. MCPyV has a 5387 bp genome and expresses T antigen proteins in MCC tumors. Most MCC are positive for an integrated MCPyV that is readily detected by PCR and by Southern blotting. In contrast only 8-16% of control tissues harbor detectable viral genome. On Southern blotting, the majority of MCPyV positive tumors show a monoclonal somatic insertion pattern suggesting that the virus contributes to clonal cell expansion. We have developed reagents required to study this new virus including infected cell lines, specific antibodies and an overlapping peptide library for the VP1 protein. Preliminary studies suggest that MCPyV is a common but not ubiquitous infection that contributes to MCC when the virus mutates and integrates into the host genome. Identification of specific biomarkers for MCPyV infection is essential to determine MCPyV's role in human cancers. We propose to develop screening blood tests for MCPyV infection using established polyomavirus immunodiagnostic techniques as well as new immunodiagnostic methods. We will identify and characterize human antibody responses to MCPyV infection using cell-based IFA, MCPyV peptide mapping and virus-like particle ELISA with sera from well-defined populations. These assays will be vetted for cross-reactivity to known human polyomaviruses to ensure assay specificity. We also propose generating specific monoclonal antibodies to be used to detect viral antigens in tissue microarrays so that common tumors can be screened for infection. Expression of viral proteins can also be correlated with cellular protein biomarker expression to determine clinical course and responsiveness to treatment. This is the first proposal for funding to study a new human tumor virus found in our laboratory, MCPyV, likely to cause Merkel cell carcinoma. Merkel cell carcinoma is a cancer of the elderly, AIDS, transplant and other immunosuppressed persons. It has the highest overall mortality rate among skin cancers and there are no specific preventive measures or diagnostic tests for MCPyV infection. If funded, this proposal will develop accurate blood assays to measure antibody proteins marking MCPyV infection and to measure viral proteins in tissues. These are required to understand human infection with this virus and to develop effective vaccines and drugs against MCPyV.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA136363-02
Application #
7691836
Study Section
AIDS-associated Opportunistic Infections and Cancer Study Section (AOIC)
Program Officer
Sorbara, Lynn R
Project Start
2008-09-25
Project End
2011-07-31
Budget Start
2009-08-01
Budget End
2010-07-31
Support Year
2
Fiscal Year
2009
Total Cost
$340,875
Indirect Cost
Name
University of Pittsburgh
Department
Genetics
Type
Schools of Medicine
DUNS #
004514360
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213
Velásquez, Celestino; Amako, Yutaka; Harold, Alexis et al. (2018) Characterization of a Merkel Cell Polyomavirus-Positive Merkel Cell Carcinoma Cell Line CVG-1. Front Microbiol 9:713
Kwun, H J; Wendzicki, J A; Shuda, Y et al. (2017) Merkel cell polyomavirus small T antigen induces genome instability by E3 ubiquitin ligase targeting. Oncogene 36:6784-6792
Kwun, Hyun Jin; Chang, Yuan; Moore, Patrick S (2017) Protein-mediated viral latency is a novel mechanism for Merkel cell polyomavirus persistence. Proc Natl Acad Sci U S A 114:E4040-E4047
Velásquez, Celestino; Cheng, Erdong; Shuda, Masahiro et al. (2016) Mitotic protein kinase CDK1 phosphorylation of mRNA translation regulator 4E-BP1 Ser83 may contribute to cell transformation. Proc Natl Acad Sci U S A 113:8466-71
Toptan, Tuna; Yousem, Samuel A; Ho, Jonhan et al. (2016) Survey for human polyomaviruses in cancer. JCI Insight 1:
Ho, Jonhan; Jedrych, Jaroslaw J; Feng, Huichen et al. (2015) Human polyomavirus 7-associated pruritic rash and viremia in transplant recipients. J Infect Dis 211:1560-5
Kwun, Hyun Jin; Shuda, Masahiro; Camacho, Carlos J et al. (2015) Restricted protein phosphatase 2A targeting by Merkel cell polyomavirus small T antigen. J Virol 89:4191-200
Wendzicki, Justin A; Moore, Patrick S; Chang, Yuan (2015) Large T and small T antigens of Merkel cell polyomavirus. Curr Opin Virol 11:38-43
Shuda, Masahiro; Velásquez, Celestino; Cheng, Erdong et al. (2015) CDK1 substitutes for mTOR kinase to activate mitotic cap-dependent protein translation. Proc Natl Acad Sci U S A 112:5875-82
Dulmage, B O; Feng, H; Mirvish, E et al. (2015) Black cat in a dark room: the absence of a directly oncogenic virus does not eliminate the role of an infectious agent in cutaneous T-cell lymphoma pathogenesis. Br J Dermatol 172:1449-51

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