Breast Cancer and Stem Cells

Cancer spheres made by laboratory generated NBLE breast cancer stem cell line. Courtesy: Anurag N. Paranjape, Ph.D. student

Cancer stem cells (CSCs) are a subpopulation of cancer cells endowed with stem cell properties and are proposed to be major drivers of tumor initiation and progression. Furthermore, being resistant to conventional therapies, the CSCs are predicted to be main culprits leading to tumor relapse. The primary focus of Dr. Rangarajan’s laboratory is to understand the origin and biology of CSCs, and to develop strategies to target them towards more effective cancer treatment.

The “stem cell theory” of cancer predicts that cancers originate in the normal, adult stem cells. To test this, Dr. Rangarajan’s group introduced various oncogenes into stem/progenitor cells of normal breast tissue cultured as floating ‘mammospheres’. A specific “oncogene combination” converted these cells into tumorigenic cells. Interestingly, a significant sub-population of these transformed cells harbored CSCs that initiated new tumors in test animals. Furthermore, gene expression analyses revealed striking similarities between the mammosphere-derived tumors generated within laboratory mice and naturally-arising breast adenocarcinomas encountered in the clinic.  This lent early evidence to the provocative notion that solid tumors may originate in adult stem cells. Further, this laboratory-generated breast “cancer stem cell line” also offers a unique system for deciphering the mechanisms of self-renewal in CSCs, and drug-screening.

Dr. Rangarajan’s contribution to the emerging field of ‘cancer stem cell biology’ earned her the National (Junior) Women Bioscientist Award by the Department of Biotechnology, Govt. of India.

Photo credit: Deepak Modi