Cancer Stem Cells and the Unicellular Life Cycle of Cancer

Abstract

Does cancer stem cells (CSCs) really originate from abnormal human stem cells (hSCs)? And is cancer a disease of cell differentiation in multicellular organisms or does it have deeper roots in the evolutionary history of life? Cancer stem cells were found in tumors of various tissues and organs as well as in established tumor cell lines. Like normal stem cells, CSCs are capable of self-renewal, quiescence, and cell differentiation. They invade other tissues and cause secondary tumors, metastases and cancer recurrence. CSCs express the embryonic stem cell markers OCT4, NANOG, SOX2 and YAP [1]. All these findings led previous cancer researchers to the assumption that CSCs arise from deficient human stem cells (hSCs). Some cancer researchers regarded cancer as a “stem cell disease” [2].