Gene Sequence Characterizes Drug Resistant Breast Cancer Stem Cells

Residual breast cancer cells that have survived conventional hormonal treatment or chemotherapy express a distinctive gene signature linked to both tumor initiation and resistance to further drug treatment.

Investigators at Baylor College of Medicine (Houston, TX, USA) had found previously that following conventional chemotherapy for breast cancer the residual cancerous tissue contained a high percentage of tumor-initiating breast cancer stem cells that were resistant to further drug treatment.

In the current study, the investigators screened breast tissue from treated patients as well as breast cancer cells growing in tissue culture for a common DNA sequence that would characterize breast stem cells. They reported in the August 3, 2009, online edition of the journal Proceedings of the [U.S.] National Academy of Sciences (PNAS) that they had found a gene signature that encoded for the CD44+/CD24−/low cell-surface antigen as being common to both residual tumor tissue and beast cancer culture cells.

"We have found that gene expression patterns in a subset of these resistant cancer cells differ from those associated with the bulk of the epithelial cells in the tumor. These patterns resemble expression patterns more closely associated with cells with a mesenchymal (a form of connective tissue) phenotype (or appearance),” said senior author Dr. Jenny Chang, professor of medicine at Baylor College of Medicine. "This study supports a growing body of evidence that there is a particular subpopulation of cells in breast cancer that may be responsible for disease recurrence, resistance to treatment, and perhaps metastasis.”

The gene signature identified in this study will now be the target of research to develop drugs that can augment conventional therapy to eradicate all populations of cells within tumors.

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Baylor College of Medicine