Attributes of Oct4 in stem cell biology: perspectives on cancer stem cells of the ovary

Epithelial ovarian cancer (EOC) remains the most lethal of all the gynaecological malignancies with drug resistance
and recurrence remaining the major therapeutic barrier in the management of the disease. Although several
studies have been undertaken to understand the mechanisms responsible for chemoresistance and subsequent
recurrence in EOC, the exact mechanisms associated with chemoresistance/recurrence continue to remain elusive.
Recent studies have shown that the parallel characteristics commonly seen between embryonic stem cells (ESCs)
and induced pluripotent stem cells (iPSC) are also shared by a relatively rare population of cells within tumors that
display stem cell-like features. These cells, termed ‘cancer initiating cells’ or ‘cancer stem cells (CSCs)’ have been
shown not only to display increased self renewal and pluripotent abilities as seen in ESCs and iPSCs, but are also
highly tumorigenic in in vivo mouse models. Additionally, these CSCs have been implicated in tumor recurrence
and chemoresistance, and when isolated have consistently shown to express the master pluripotency and
embryonic stem cell regulating gene Oct4. This article reviews the involvement of Oct4 in cancer progression and
chemoresistance, with emphasis on ovarian cancer. Overall, we highlight why ovarian cancer patients, who initially
respond to conventional chemotherapy subsequently relapse with recurrent chemoresistant disease that is
essentially incurable.