Glioblastomas are one of the most aggressive and commonly occurring brain tumors (1) Patients diagnosed with glioblastomas have a life expectancy of about fourteen months with medical treatments, including surgery, chemotherapy, and radiation therapy. Although common and lethal, the causes of glioblastomas and effective treatments still remain unclear to the medical field. In fact, one of the most commonly used medications in chemotherapy, temozolomide, tends to only be temporarily effective with cancer relapsing in a few months. (1) To develop more effective therapies to treat glioblastomas, researchers must first understand the disease itself, pinpointing what factors make the cancer cells so aggressive, and how to bypass these factors.
Through a study of the genetic evolution of glioblastomas, scientists have found that the recurrence of cancer might be due to the presence of certain cancers cells that have similar properties to those of stem cells. Because cancer stem cells have the ability to differentiate into all cell types, they could easily self-renew and form new tumorous cells. Specifically in this study, glioblastoma stem-cell like cells (or GSCs) are subclones to the cancer cells in the primary cancer. (1) However, GSCs are distinct in that they exhibit different genetic characteristics, which would help them survive chemotherapy treatments unlike their normal cancer cell counterparts. (1) A comparison of the cells in the primary tumor with those of the recurrent tumor reveals that there are common cell types present in both tumors. (1) The study concludes that there is a possibility that after surviving through the chemotherapy, the subclones would go through genetic evolution under therapeutic pressure, similar to the differentiation process that stem cells go through in response to signals sent by transcription factors and growth factors. (1)
Moreover, this evolution process tends to increase those cancer cells’ resistance to chemotherapy, making suppression of recurrent tumors even more difficult. In most cases, cancer cells in patients with relapsing tumors would not respond to chemotherapy treatments as effectively as the first time, making it even more difficult to treat the relapsing tumors. (1) As shown in this study, the recurrent tumors, while revealing similar phylogenetic characteristics as primary tumors, glioblastoma stem cell-like cells also exhibit divergent accumulation of mutations, which means that these tumors might have evolved genetically and possess different properties from primary tumors. (1)
Weiwen Cui is currently a Freshman at UC Berkeley. Growing up in a physician family, she has always wanted to learn more about diseases and treatments for them. After taking a DeCal course at UC Berkeley, Weiwen realized her interests in stem cells and the related research, and decided to become a guest blogger for SSSCR. Outside academics, she also likes reading, traveling, and tennis.