Cancer stem cells and ovarian cancer : Characteristics, importance and potential applications in clinical practice
Abstract
Ovarian cancer is the most malignant and the second most common gynecological cancer which encompasses a heterogeneous group of tumors with a different etiology. Extra-ovarian tissues may play a role in the development of ovarian cancer, despite this issue is still debated.
This disease is associated with a strong chemoresistance and tendency to recurrence, and asymptomatic behaviour at early stages. Effective screening markers have not been established yet.
Cancer stem cells have been postulated to play a role within tumor formation and by the establishment of chemotherapy-resistant population of malignant cells after the surgery and application of chemotherapy. These cells are multipotent cells capable of un-limited divisions and have potential to induce tumorigenesis in immune-suppressed mice.
Their detailed characterization is still an open issue, however there have been identified several markers associated with ovarian cancer stem cells. The major markers of ovarian cancer stem cells identified so far are CD133, ALDH, CD44, CD117, CD24 and EpCAM.
Their occurrence in primary tumors may be associated with patients' prognosis; however there are insufficient data for definite conclusions. Dynamic processes of carcinogenesis result also in changes of cancer stem cells phenotypes based on the microenvironmental changes within the tumor.
The markers may thus be acquired, or lost, as it has been proven experimentally. As regards the possibility to use targeted, specific therapy approaches, there are some promising studies, suggesting this may be a method of potential treatment.
Further characterization and functional studies of cancer stem cells will be necessary for the elucidation of carcinogenesis, chemoresistance and metastases formation-associated processes. The most recent results on ovarian cancer stem cells research are presented in this paper.