[if: I don't think we've seen this before. Apologies if we have - I did search + visually scan]
Journal of Virology, February 2010, p. 1874-1880, Vol. 84, No. 4
0022-538X/10/$012.00+0 doi:10.1128/JVI.01941-09
Copyright 2010, American Society for Microbiology. All Rights Reserved.
The Prostate Cancer-Associated Human Retrovirus XMRV Lacks Direct Transforming Activity but Can Induce Low Rates of Transformation in Cultured Cells{triangledown}
Michael J. Metzger, Christiana J. Holguin, Ramon Mendoza, and A. Dusty Miller*
Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, Washington 98109-1024
Received 13 September 2009/ Accepted 30 November 2009
The human retrovirus XMRV (xenotropic murine leukemia virus-related virus) is associated with prostate cancer, but a causal relationship has not been established. Here, we have used cultured fibroblast and epithelial cell lines to test the hypothesis that XMRV might have direct transforming activity but found only rare transformation events, suggestive of indirect transformation, even when the target cells expressed the human Xpr1 cell entry receptor for XMRV. Characterization of cells from three transformed foci showed that all were infected with and produced XMRV, and one produced a highly active transforming virus, presumably generated by recombination between XMRV and host cell nucleic acids. Given the sequence similarity of XMRV to mink cell focus-forming (MCF) viruses and the enhanced leukemogenic activity of the latter, we tested XMRV for related MCF-like cytopathic activities in cultured mink cells but found none. These results indicate that XMRV has no direct transforming activity but can activate endogenous oncogenes, resulting in cell transformation. As part of these experiments, we show that XMRV can infect and be produced at a high titer from human HT-1080 fibrosarcoma cells that express TRIM5{alpha} (Ref1), showing that XMRV is resistant to TRIM5{alpha} restriction. In addition, XMRV poorly infects NIH 3T3 cells expressing human Xpr1 but relatively efficiently infects BALB 3T3 cells expressing human Xpr1, showing that XMRV is a B-tropic virus and that its infectivity is regulated by the Fv1 mouse locus.
* Corresponding author. Mailing address: Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N., Seattle, WA 98109-1024. Phone: (206) 667-2890. Fax: (206) 667-6523. E-mail: dmiller@fhcrc.org
{triangledown} Published ahead of print on 9 December 2009.
Journal of Virology, February 2010, p. 1874-1880, Vol. 84, No. 4
0022-538X/10/$012.00+0 doi:10.1128/JVI.01941-09
Copyright 2010, American Society for Microbiology. All Rights Reserved.
Journal of Virology, February 2010, p. 1874-1880, Vol. 84, No. 4
0022-538X/10/$012.00+0 doi:10.1128/JVI.01941-09
Copyright 2010, American Society for Microbiology. All Rights Reserved.
The Prostate Cancer-Associated Human Retrovirus XMRV Lacks Direct Transforming Activity but Can Induce Low Rates of Transformation in Cultured Cells{triangledown}
Michael J. Metzger, Christiana J. Holguin, Ramon Mendoza, and A. Dusty Miller*
Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, Washington 98109-1024
Received 13 September 2009/ Accepted 30 November 2009
The human retrovirus XMRV (xenotropic murine leukemia virus-related virus) is associated with prostate cancer, but a causal relationship has not been established. Here, we have used cultured fibroblast and epithelial cell lines to test the hypothesis that XMRV might have direct transforming activity but found only rare transformation events, suggestive of indirect transformation, even when the target cells expressed the human Xpr1 cell entry receptor for XMRV. Characterization of cells from three transformed foci showed that all were infected with and produced XMRV, and one produced a highly active transforming virus, presumably generated by recombination between XMRV and host cell nucleic acids. Given the sequence similarity of XMRV to mink cell focus-forming (MCF) viruses and the enhanced leukemogenic activity of the latter, we tested XMRV for related MCF-like cytopathic activities in cultured mink cells but found none. These results indicate that XMRV has no direct transforming activity but can activate endogenous oncogenes, resulting in cell transformation. As part of these experiments, we show that XMRV can infect and be produced at a high titer from human HT-1080 fibrosarcoma cells that express TRIM5{alpha} (Ref1), showing that XMRV is resistant to TRIM5{alpha} restriction. In addition, XMRV poorly infects NIH 3T3 cells expressing human Xpr1 but relatively efficiently infects BALB 3T3 cells expressing human Xpr1, showing that XMRV is a B-tropic virus and that its infectivity is regulated by the Fv1 mouse locus.
* Corresponding author. Mailing address: Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N., Seattle, WA 98109-1024. Phone: (206) 667-2890. Fax: (206) 667-6523. E-mail: dmiller@fhcrc.org
{triangledown} Published ahead of print on 9 December 2009.
Journal of Virology, February 2010, p. 1874-1880, Vol. 84, No. 4
0022-538X/10/$012.00+0 doi:10.1128/JVI.01941-09
Copyright 2010, American Society for Microbiology. All Rights Reserved.
:tear: 
