Researchers at UCLA's Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research have discovered a mechanism in adult stem cells by which the cells suppress their ability to initiate cancer during their dormant phase, an understanding that could be exploited for better cancer prevention strategies. The study was led by Andrew White, post-doctoral fellow, and William Lowry, associate professor of molecular, cell and developmental biology in the life sciences and the Maria Rowena Ross Term Chair in Cell Biology.
The study was published online ahead of print in Nature Cell Biology on December 15, 2013.
Hair follicle stem cells (HFSC), the tissue-specific adult stem cells that generate the hair follicles, are also the cells of origin for cutaneous squamous cell carcinoma (SCC), a common skin cancer. These HFSCs cycle between periods of activation, during which they can grow, and quiescence, when they remain dormant.
Using mouse models, White and Lowry applied known cancer-causing genes (oncogenes) to HFSCs and found that during cell quiescence, the cells could not be made to initiate SCC. Once the HFSC were in their active period, they began growing cancer.
“We found that this tumor suppression via adult stem cell quiescence was mediated by Pten, a gene important in regulating the cell's response to signaling pathways,” White said, “therefore, stem cell quiescence is a novel form of tumor suppression in hair follicle stem cells, and Pten must be present for the suppression to work.”
Understanding cancer suppression through quiescence could better inform preventative strategies in patients susceptible to SCC, such as organ transplant patients, or those taking the drug vemurafenib for melanoma, another type of skin cancer. This study also may reveal parallels between SCC and other cancers in which stem cells have a quiescent phase.
In mitotic cells there is the interphase which could be said as a dormant stage. Is there such an interphase in adult stem cells? Does a stem cell undergo four phases that mitotic adult cell undergoes to produce two daughter cells? Is there a way to prolong the interphase stage in both the adult stem cell and the mitotic adult cell? it is probable that the cancerous adult mitotic cells have acquired damage like injury in DNA when still adult stem cells to turn cancerous as adult mitotic cells.