WEDNESDAY, July 19 (HealthDay News) -- A stem cell-like "side population" of ovarian cancer cells may explain why the cancer tends to become drug resistant with time, according to the results of an animal and human cell study published online July 18 in the Proceedings of the National Academy of Sciences Early Edition.
Patricia K. Donahoe, M.D., of the Massachusetts General Hospital and Harvard Medical School in Boston, and colleagues identified side populations of cells in two murine ovarian cancer cell lines that expressed breast cancer-resistance protein 1, which produces drug resistance by pumping lipophilic drugs out of the cell. Both cell lines had relatively large populations of such cells and may be good models for the study of ovarian cancer.
The researchers found that the side population cells formed tumors more quickly in mice than non-side population cells. Mullerian Inhibiting Substance (MIS) inhibited the proliferation of both cell types, but doxorubicin killed non-side population cells more effectively than side population cells. Similar types of stem cell-like cells were identified in human ovarian cancer cell lines and primary human ascites cells.
"A clinical testing model of side population cells or even purer subsets within the side population fraction are predicted to yield a more reliable insight into the development of effective therapeutic agents," the authors conclude. "Further work is needed and underway to more clearly define primary human ovarian cancer stem cells and their response to MIS in vivo."
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