Survival of the Fittest: Cancer Stem Cells in Therapeutic Resistance and Angiogenesis

In an increasing number of cancers, tumor populations called cancer stem cells (CSCs), or tumor-initiating cells, have been defined in functional assays of self-renewal and tumor initiation. Moreover, recent work in several different cancers has suggested the CSC population as a source of chemotherapy and radiation-therapy resistance within tumors. Work in glioblastoma and breast cancers supports the idea that CSCs may possess innate resistance mechanisms against radiation- and chemotherapy-induced cancer cell death, allowing them to survive and initiate tumor recurrence. Several resistance mechanisms have been proposed, including amplified checkpoint activation and DNA damage repair as well as increased…