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Arora, Reety (2012) MERKEL CELL POLYOMAVIRUS POSITIVE MERKEL CELL CARCINOMA - FROM DIAGNOSIS TO THERAPY. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Merkel cell polyomavirus (MCV) is one of the newer members of the polyomavirus family, recently discovered as clonally integrated into the genomes of a subset of Merkel cell carcinoma (MCC). MCV is the first polyomavirus that is widely accepted to cause a human cancer and its identification has resulted in a paradigm shift in the understanding of MCC biology. In the vast majority of the population, MCV is a harmless member of the normal human microbial flora, but can initiate an aggressive cancer if it integrates into the host genome and acquires a precise set of viral mutations that result in replication incompetence (in a susceptible host).
This dissertation describes how the identification of a new viral cause of MCC was harnessed to develop new diagnostic assays and therapeutic options for MCC. To assess MCV infection and its association with MCC as well as other human diseases, a monoclonal antibody that specifically recognizes both endogenous and transfected MCV large T antigen was developed. Using this antibody, specific nuclear localization of MCV T antigen in MCC tumor cells was demonstrated. A quantitative PCR assay revealed that MCV is present in MCC at >1 copy per tumor cell. These assays were used to survey non-MCC tissues including hematolymphoid malignancies, neuroendocrine tumors, and various dermatologic cancers.None showed association with MCV infection. Restricted expression of the MCV LT oncoprotein to MCC tumor cells provides the mechanistic underpinning supporting the notion that MCV causes a subset of MCC.
To investigate treatment options for MCC two methods were used. An in vitro drug screen of 1360 chemotherapeutic and pharmacologically active compounds resulted in the identification of a proteasome inhibitor, bortezomib, as a potent but nonselective candidate. To rationally and specifically target MCV positive MCC, deep-sequence profiles of MCV positive MCC tumors were compared to MCV negative MCC tumors. Among 64 cell death related genes, a seven fold differential expression of survivin was observed in MCV positive MCC. MCV T antigen knock down in MCV positive cell lines decreased survivin mRNA and protein expression. Also, exogenously expressed MCV T antigen increased survivin protein in non-MCC primary cells in an RB protein binding dependent manner. A survivin inhibitor, YM155 initiated selective nonapoptotic MCV positive MCC cell death. YM155 was nontoxic and halted MCV positive MCC xenograft tumor growth in mice while bortezomib was inactive and caused significant toxicity in vivo.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Arora, Reetyrea25@pitt.eduREA25
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairChang, Yuanyc70@pitt.eduYC70
Committee MemberKhan, Saleemkhan@pitt.eduKHAN
Committee MemberBrodsky, Jeffreyjbrodsky@pitt.eduJBRODSKY
Committee MemberPipas, Jamespipas@pitt.eduPIPAS
Committee MemberSmithgall, Thomastsmithga@pitt.eduTSMITHGA
Thesis AdvisorChang, Yuanyc70@pitt.eduYC70
Date: 10 May 2012
Date Type: Publication
Defense Date: 4 May 2012
Approval Date: 10 May 2012
Submission Date: 9 May 2012
Access Restriction: 5 year -- Restrict access to University of Pittsburgh for a period of 5 years.
Number of Pages: 260
Institution: University of Pittsburgh
Schools and Programs: School of Medicine > Integrative Molecular Biology
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: cancer, malignancy, virus, tumor virus, Merkel cell carcinoma, polyomavirus, survivin, drug screen, CM2B4 antibody, diagnosis, therapy
Date Deposited: 10 May 2012 11:47
Last Modified: 10 May 2017 05:15


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