Jemal
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Replication Competent Murine Gammaretroviruses in Commonly Used Prostate Cancer Cell Lines
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http://www.plosone.org/article/info:doi/10.1371/journal.pone.0020874
Citation: Sfanos KS, Aloia AL, Hicks JL, Esopi DM, Steranka JP, et al. (2011) Identification of Replication Competent Murine Gammaretroviruses in Commonly Used Prostate Cancer Cell Lines. PLoS ONE 6(6): e20874. doi:10.1371/journal.pone.0020874
Editor: Jean-Pierre Vartanian, Institut Pasteur, France
Received: February 24, 2011; Accepted: May 11, 2011; Published: June 17, 2011
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There are also reports of retroviral infection of cell lines that clearly occurred during passage in culture, as the lines were never passaged in mice [9], [11]. Additional potential sources of cell line infection with retroviruses include laboratory contamination and the use of retroviral vectors in research [9]. Importantly, there are only rare examples where retroviral presence in cultured human cells could be traced back to a true infection of the patient. One well established example of this is the discovery of the human T-lymphotropic virus type 1 (HTLV-1) in cultured cells from patients with T-cell lymphomas [12].
The discovery of XMRV in the CWR22Rv1 cell line prompted us to interrogate additional prostate cancer cell lines for the presence of XMRV or other murine gammaretroviruses. If the source of retroviral infection is not from the prostate cancer patient, but introduced by passage through animals or laboratory contamination, then the presence of replication competent retroviruses in commonly used prostate cancer cell lines for research could potentially have confounding effects on experimental outcomes.
Out of concern that prostate cancer cell lines producing replication competent viruses could cross-contaminate other cell lines in our laboratory which are negative for MLVs, we tested current cultures in our laboratory for the presence of MLVs. We were surprised to find two instances where MLV-negative cell lines maintained in the laboratory (DU145, LNCaP) have become contaminated with MLVs (Figure S5). For example, when these cell lines were obtained directly from ATCC (LNCaP) or the NCI (DU145) they were negative for virus, indicating that the lines were contaminated at some point during culture in the laboratory. PCR analysis with XMRV-specific primers indicated that the contaminating virus was likely XMRV, potentially from culture alongside CWR22Rv1 (data not shown). These results suggest that if CWR22Rv1 cells are routinely cultured in a typical biomedical research laboratory setting (e.g. using standard Class II biosafety cabinets and procedures for cell culture in which two different cell lines are never present under the hood at the same time), that XMRV can infect and contaminate other cell lines.
Our study demonstrates that prostate cancer cell lines appear to have a propensity for infection by murine gammaretroviruses. We propose that this tendency may be due to the fact that most of the established prostate cancer cell lines were created by passage through immunocompromised mice. In fact, Bxv-1 is present in SCID and nude mice and tumor cells passaged through these animals can become infected with xenotropic MLVs [22]. Although the infection of human cell lines with murine gammaretroviruses has been previously described in the literature, what makes our current study particularly important is that prior to this study it was not known that multiple commonly used prostate cancer cell lines are contaminated with MLVs. In fact, we discovered during the course of our study that other cell lines maintained in the laboratory (DU145, LNCaP) have apparently become infected with XMRV in the laboratory.
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0020874