Subset of Cancer Stem Cells Found to Suppress Chemotherapy Agent

New research suggests that for chemotherapy to be effective in treating lung cancers, it must be able to target a small subset of cancer stem cells, which they have shown share the same protective mechanisms as normal lung stem cells.

Current cancer therapies often succeed at initially eliminating the bulk of the disease, including all rapidly proliferating cells, but are eventually thwarted because they cannot eliminate a small reservoir of multiple-drug-resistant tumor cells, called cancer stem cells, which ultimately become the source of disease recurrence and eventual metastasis.

Scientists from the University of Pittsburgh School of Medicine (PA, USA) presented this groundbreaking study at the Tissue Engineering and Regenerative Medicine International Society (TERMIS) North American Chapter meeting being held June 13-16, 2007, in Toronto, Canada.

The University of Pittsburgh researchers, led by Vera Donnenberg, Ph.D., assistant professor of surgery and pharmaceutical sciences, University of Pittsburgh Schools of Medicine and Pharmacy, utilized cell-surface markers and dyes to identify cancer stem cells as well as normal adult stem cells and their progeny in samples obtained from normal lung and lung cancer tissue samples. The researchers identified a very small, rare set of resting cancer stem cells in the lung cancer samples that looked and behaved much like normal adult lung tissue stem cells. Both the cancer and normal stem cells were protected equally by multiple drug resistance transporters, even if most of the tumor responded to chemotherapy.

According to Dr. Donnenberg, the very fact that cancers can and do relapse after apparently successful therapy indicates the survival of a drug-resistant, tumor-initiating population of cells in many types of refractory cancers. "Because of the similarities between the way that normal stem cells and cancer stem cells protect themselves, cancer therapies have to be designed specifically to target cancer stem cells while sparing normal stem cells,” she explained.


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