Abstract

Molecular biological investigations of the last decade have not been able to definitively determine the source of oncogenic transformation [1]. In recent years, the theory of carcinogenesis by CSCs has become increasingly plausible [2], but where do the CSCs come from? So far, the origin of CSCs has been obscure and controversial [3]. At first, CSCs and normal human stem cells hSCs seem to be strongly related. They have both the capacity for self-renewal and multilineage differentiation. Accordingly, CSCs were thought to originate from normal stem cell mutants, progenitor cell mutants or transiently amplifying cells of unregulated self-renewal ability [4]. Other researchers thought that CSCs originated from adult cells by de-differentiation [5-7] or by de-differentiation of mutated cells that create stem cell-like characteristics. In other words, a fully differentiated cell undergoes mutations or extracellular signals that drive it back to a stem-like state(a). Even today, the origin of CSCs is vague and ambiguous.