title: Merkel cell polyomavirus-infected Merkel cell carcinoma cells require expression of viral T antigens.
abstract: Merkel cell carcinoma (MCC) is the most aggressive skin cancer. Recently, it was demonstrated that human Merkel cell polyomavirus (MCV) is clonally integrated in approximately 80% of MCC tumors. However, direct evidence for whether oncogenic viral proteins are needed for the maintenance of MCC cells is still missing. To address this question, we knocked down MCV T-antigen (TA) expression in MCV-positive MCC cell lines using three different short hairpin RNA (shRNA)-expressing vectors targeting exon 1 of the TAs. The MCC cell lines used include three newly generated MCV-infected cell lines and one MCV-negative cell line from MCC tumors. Notably, all MCV-positive MCC cell lines underwent growth arrest and/or cell death upon TA knockdown, whereas the proliferation of MCV-negative cell lines remained unaffected. Despite an increase in the number of annexin V-positive, 7-amino-actinomycin D (7-AAD)-negative cells upon TA knockdown, activation of caspases or changes in the expression and phosphorylation of Bcl-2 family members were not consistently detected after TA suppression. Our study provides the first direct experimental evidence that TA expression is necessary for the maintenance of MCV-positive MCC and that MCV is the infectious cause of MCV-positive MCC.
authors.affiliation: Molecular Virology Program, University of Pittsburgh Cancer Institute, 5117 Centre Ave., Pittsburgh, PA 15213, USA.
authors.forename: Roland
authors.initials: R
authors.lastname: Houben
authors.forename: Masahiro
authors.initials: M
authors.lastname: Shuda
authors.forename: Rita
authors.initials: R
authors.lastname: Weinkam
authors.forename: David
authors.initials: D
authors.lastname: Schrama
authors.forename: Huichen
authors.initials: H
authors.lastname: Feng
authors.forename: Yuan
authors.initials: Y
authors.lastname: Chang
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Moore
authors.forename: Jürgen C
authors.initials: JC
authors.lastname: Becker
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000952:Antigens, Polyomavirus Transforming / Q000235:genetics / Q000378:metabolism*; D015266:Carcinoma, Merkel Cell / Q000473:pathology / Q000821:virology*; D002453:Cell Cycle / Q000502:physiology; D045744:Cell Line, Tumor; D002470:Cell Survival; D005260:Female; D055785:Gene Knockdown Techniques; D006801:Humans; D008297:Male; D008875:Middle Aged; D011120:Polyomavirus / Q000276:immunology* / Q000378:metabolism; D027601:Polyomavirus Infections / Q000378:metabolism / Q000473:pathology / Q000821:virology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology / Q000821:virology*
chemical_list: D000952:Antigens, Polyomavirus Transforming; D019253:Proto-Oncogene Proteins c-bcl-2
references.citation: PLoS One. 2009;4(3):e4958
references.pmid: 19305499
references.citation: J Am Acad Dermatol. 2010 Sep;63(3):400-3
references.pmid: 20584559
references.citation: PLoS Pathog. 2009 Mar;5(3):e1000363
references.pmid: 19325891
references.citation: Cancer Res. 2006 Dec 1;66(23):11348-59
references.pmid: 17145881
references.citation: Science. 2008 Feb 22;319(5866):1096-100
references.pmid: 18202256
references.citation: J Am Acad Dermatol. 1993 Nov;29(5 Pt 1):715-22
references.pmid: 8227544
references.citation: J Invest Dermatol. 2009 Jan;129(1):246-8
references.pmid: 18650846
references.citation: J Virol. 2009 Dec;83(23):12118-28
references.pmid: 19759150
references.citation: Oncogene. 2005 Nov 21;24(52):7746-55
references.pmid: 16299534
references.citation: Int J Cancer. 2002 Sep 10;101(2):137-45
references.pmid: 12209990
references.citation: Int J Cancer. 1995 Jan 3;60(1):100-7
references.pmid: 7814141
references.citation: Int J Cancer. 2006 Jun 15;118(12):3030-44
references.pmid: 16404738
references.citation: J Invest Dermatol. 2009 Jan;129(1):250-2
references.pmid: 18650847
references.citation: J Exp Med. 1980 Dec 1;152(6):1709-19
references.pmid: 6778951
references.citation: Am J Surg Pathol. 2009 Sep;33(9):1378-85
references.pmid: 19609205
references.citation: J Natl Cancer Inst. 2009 Nov 4;101(21):1510-22
references.pmid: 19776382
references.citation: Science. 1996 Sep 6;273(5280):1384-6
references.pmid: 8703072
references.citation: Int J Cancer. 2009 Sep 15;125(6):1243-9
references.pmid: 19499546
references.citation: Virus Res. 1999 Jan;59(1):113-27
references.pmid: 10854170
references.citation: Exp Dermatol. 2009 Mar;18(3):193-8
references.pmid: 19400830
references.citation: Proc R Soc Med. 1965 May;58:295-300
references.pmid: 14283879
references.citation: PLoS Pathog. 2009 Sep;5(9):e1000578
references.pmid: 19750217
references.citation: J Clin Oncol. 2006 Sep 10;24(26):4356-65
references.pmid: 16963733
references.citation: Proc Natl Acad Sci U S A. 2008 Oct 21;105(42):16272-7
references.pmid: 18812503
references.citation: Oncogene. 2006 Aug 28;25(38):5277-85
references.pmid: 16936748
references.citation: J Surg Oncol. 2005 Jan 1;89(1):1-4
references.pmid: 15611998
references.citation: Virology. 2009 Feb 20;384(2):304-16
references.pmid: 19022468
references.citation: Lancet. 2002 Feb 9;359(9305):497-8
references.pmid: 11853800
references.citation: Int J Cancer. 2010 Apr 1;126(7):1724-31
references.pmid: 19810102
references.citation: J Invest Dermatol. 2009 Jan;129(1):248-50
references.pmid: 18633441
references.citation: Int J Cancer. 2009 Sep 15;125(6):1250-6
references.pmid: 19499548
references.citation: Nat Med. 2005 Jul;11(7):725-30
references.pmid: 16015365
references.citation: J Virol. 1992 Jul;66(7):3979-85
references.pmid: 1318392
references.citation: J Pathol. 2009 May;218(1):48-56
references.pmid: 19291712
references.citation: Semin Cancer Biol. 2009 Aug;19(4):218-28
references.pmid: 19505649
references.citation: Oncogene. 2006 Aug 28;25(38):5286-93
references.pmid: 16936749
references.citation: Oncogene. 2005 Nov 21;24(52):7729-45
references.pmid: 16299533
references.citation: Cell Mol Life Sci. 2009 Jan;66(1):1-8
references.pmid: 19023519
references.citation: Cancer Res. 2008 Jul 1;68(13):5009-13
references.pmid: 18593898
references.citation: J Natl Cancer Inst. 2009 Jul 1;101(13):938-45
references.pmid: 19535775
references.citation: J Am Acad Dermatol. 2008 Mar;58(3):375-81
references.pmid: 18280333
references.citation: Mol Oncol. 2009 Aug;3(4):366-75
references.pmid: 19559660
references.citation: EMBO J. 1993 Dec;12(12):4739-46
references.pmid: 8223482
references.citation: Int J Cancer. 2009 Jul 15;125(2):356-61
references.pmid: 19384948
references.citation: J Immunol. 1998 Jun 1;160(11):5239-45
references.pmid: 9605119
references.citation: Science. 1994 Dec 16;266(5192):1865-9
references.pmid: 7997879