Mitochondrial mass and DNA repair in breast cancer stem cells

Two recent studies by Lisanti and co-workers provide new insights into the importance of mitochondria and the cancer stem cell and its resistance to therapy. Lisanti demonstrated that WNT1/FGF3 enhances breast cancer stem cell (BCSC) expansion via a paracrine loop associated with the induction of mitochondrial biogenesis [1]. Furthermore, Lisanti showed that mitochondria are enriched within BCSC, and that mitochondrial enriched human BCSC are resistant to DNA damage [2]. These finding are consistent with the prior findings that stem cells are resistant to current therapies due to increased DNA repair capacity. The findings by Lisanti are also consistent with prior studies in which an RNAi screen identified Wnt as an inducer of mitochondrial biogenesis [3]. Importantly these studies add to the growing understanding that, in contrast with the reduction in mitochondrial mass in normal stem cells, mitochondrial protein abundance is increased in cancer stem cells.