ABSTRACT
Cancer stem cells (CSCs) are units in cancer evolution.The elucidation the origin of CSCs has great significance on prevention and treatment of cancers.This paper discusses possible origins,genetic pathways and mechanisms of CSC on the basis of the literature and authors' research.Normal stem cells could be malignantly transformed to CSC through long term accumulation of gene mutations.Induction to pluripotent stem cells by reprogramming is a possible pathway for somatic cells to become CSCs.Dedifferentiation of cancer cells to CSCs is another pathway.Epithelial-mesenchymal transition (EMT),which is an important mechanism for cellular plasticity,plays important roles in cancer metastasis and stemness of cancer cells.Cell-fusion inducing EMT could be a mechanism for the genesis of CSCs.Infection of some virus is also related to the genesis of CSCs.The complexity of cancer biology was also discussed.