Replication Competent Murine Gammaretroviruses in Commonly Used Prostate Cancer Cell

[Jemal]

Replication Competent Murine Gammaretroviruses in Commonly Used Prostate Cancer Cell Lines

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

Some random quotes:

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

 

[Jemal]

I think this study can be used to build a case both for and against XMRV?

You could say: "See, more evidence of contamination."
Or: "Even with Class II biosafety material and procedures, these murine gammaretroviruses are spreading inside laboratories. What if they managed to escape those labs? These viruses can infect human cells."

 

[Jemal]

I am getting the sick feeling this really all might have started with a contamination event... and that we are now products of that event.

 

[Enid]

Thanks Jemal - as a non scientist I'm looking forward to hearing quite what is this saying (and how it may relate to 2 friends - one XMRV positive and one MLV positive - if possible). Any explanation gratefully received. On a personal note I should add my old Dad died of Prostrate Cancer so closely related.

 

[omerbasket]

Listen, their study could be of importance, especially for future findings, but I don't understand what they are trying to say about XMRV.
First of all, they didn't find any XMRV. Second of all, the MLVs that they found were found in cell lines that were never used in the XMRV studies, at least not in the positive studies about ME/CFS (the WPI/NCI/CC study and the FDA/NIH study [which, by the way, I think that in that study they didn't use any cell line at all]).
Now, the WPI are checking their cell-lines every week for contamination. Moreover, if I'm not mistaken their 67% figure was reached without using a cell line.
Besides that, I doubt if the WPI ever had in their laboratories those cell lines that were found to be MLV-positive in the current study. That is because the WPI is exploring ME/CFS and other neuroimmune diseases, and not cancer. For the XMRV study, it is only known that the WPI used the following three cell lines: Raji, LNCaP and Sup-T1 cells.

Their conclusion, that "cancer cell lines should undergo routine screening for contaminating MLVs, much like the current practice of routine testing of cultured cells for mycoplasma" seems very reasonable to me, and I tend to agree with them. But I don't see the relevance for the XMRV-ME/CFS (or XMRV-prostate cancer) studies, and currently there is no indication for a connection between their findings and the findings of XMRV in human beings.

 

[Enid]

Thanks for your info omerbasket - guess this adds to the (necessarily) slow and painstaking researches being done/needed.

 

[Jemal]

Listen, their study could be of importance, especially for future findings, but I don't understand what they are trying to say about XMRV.
First of all, they didn't find any XMRV. Second of all, the MLVs that they found were found in cell lines that were never used in the XMRV studies, at least not in the positive studies about ME/CFS (the WPI/NCI/CC study and the FDA/NIH study [which, by the way, I think that in that study they didn't use any cell line at all]).
Now, the WPI are checking their cell-lines every week for contamination. Moreover, if I'm not mistaken their 67% figure was reached without using a cell line.
Besides that, I doubt if the WPI ever had in their laboratories those cell lines that were found to be MLV-positive in the current study. That is because the WPI is exploring ME/CFS and other neuroimmune diseases, and not cancer. For the XMRV study, it is only known that the WPI used the following three cell lines: Raji, LNCaP and Sup-T1 cells.

Their conclusion, that "cancer cell lines should undergo routine screening for contaminating MLVs, much like the current practice of routine testing of cultured cells for mycoplasma" seems very reasonable to me, and I tend to agree with them. But I don't see the relevance for the XMRV-ME/CFS (or XMRV-prostate cancer) studies, and currently there is no indication for a connection between their findings and the findings of XMRV in human beings.

Thanks for your take on this study Omer!

Then this study might actually say more about the security at some of these labs that use these cell lines? It doesn't sound too great that despite certain safety measures, other cell lines got "magically" infected as well?

 

[omerbasket]

Thanks for your info omerbasket - guess this adds to the (necessarily) slow and painstaking researches being done/needed.

I agree with that - I think that this tudy adds information, which is good - but it's only good of people do not misinterpret it and do too much of it. Perhaps some day this study would be able to help explain us something more than what it explains us today (which is that those cell lines that they checked are infected with MLVs, and that somehow their DU145 and LNCaP cell lines got infected with XMRV, even though they weren't infected with it before it reached their lab).

Thanks for your take on this study Omer!

Then this study might actually say more about the security at some of these labs that use these cell lines? It doesn't sound too great that despite certain safety measures, other cell lines got "magically" infected as well?

I too find it hard to understand what happened there. I doubt that the virus jumped into the cell lines. I guess that they did something with it, or to it, that got it infected, or that some of their tests were wrong for some reason (perhaps contaminated reagents?), or I don't know how. But if the virus decided just to move by itself to those cell lines... Well, then it is the world's first, as far as we know.

 

[Bob]

Link for this study:
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0020874

 

[Jemal]

Thanks Bob, I somehow forgot the link... edited the first post and added it.