by Lizzie Bennett
A University of Massachusetts Amhurst and Harvard Medical School combined research team have found that have found that several FDA approved chemotherapy drugs have the side effect of inducing stem cell tumours. Michele Markstein Of Amherst and Norbert Perrimon from Harvard found that the treatments lead to hyper proliferation in stem cells, and this is proven to lead to tumours and/or tumour recurrence.
“We discovered that several chemotherapeutics that stop fast growing tumors have the opposite effect on stem cells in the same animal, causing them to divide too rapidly. This was a surprise, because it showed that the same drug could have opposite actions on cells in the same animal: Suppressing tumor growth on one cell population while initiating growth in another. Not only is the finding of clinical interest, but with this study we used an emerging new non-traditional tool for assessing drugs using stem cells in the fruit fly gut.”
She adds, “We did these experiments in the fly because Drosophila stem cells, in the intestine, are very much like the stem cells in our intestine, and it’s a lot easier to do experiments in flies than humans or even mice.”
Further, Markstein explains, “When it comes to stem cells, it is important to conduct studies in living animals because stem cells are acutely attuned to the other cells in their microenvironment. Indeed the side effect that we observed is caused by damage that the chemotherapy drugs to cells in the stem cell microenvironment. The stem cells respond to this damage by hyper proliferating.”
The team has proved definitively that the fruit flies are sensitive to human chemotherapy drugs.
“We systematically fed the FDA-approved drugs to the flies and found that 14 suppressed tumor growth in the intestine. This was a great result, validating the relevance of flies as a clinical model. It was also very interesting, however, that we found that half these tumor-suppressing drugs had the opposite effect on the non-tumor stem cells, causing them to over-proliferate. This resulted in small growths or ‘tumors,’ that with the right genetic background could potentially become cancerous.”
Once again the Food and Drug Administration has approved drugs that can do more harm than good. They also approved the HPV vaccines Gardasil and Cervarix, which the lead developer later admitted could lead to devastating consequences.
The work of Markstein and Perrimon is backed up by other studies into the effect of Doxorubicin, a chemotherapy drug, in mice. Although the pathway that triggered the response was different the result was the same. The Mice showed a large increase in the inflammatory response which is known to trigger cancers.