According to the theory of cancer stem cells, tumors consist of a heterogeneous cell population in which only few cells endowed with tumorigenic potential are able to sustain tumor growth and progression. To test the hypothesis of cancer stem cells in human melanomas, melanoma cells obtained both from fresh tumor specimens and melanoma cell lines were cultured in Stem Cell Medium (SCM). Cells growing as melanospheres and displaying self-renewing capacity and multipotency were established starting both from fresh tumor specimens and melanoma cell lines. Melanosphere-derived cells were endowed with strong tumor initiating potential and intradermal injections of as few as 101/102 cells generated tumors in SCID mice. Moreover tumorigenic potential was maintained into secondary and tertiary recipients. Primary xenografts and serially transplanted tumors displayed the same heterogeneous expression pattern of melanoma markers found in the patient\#8217;s original tumor as evaluated by histological staining. Expression of stem cell markers such as CD133, CD166, and neural crest-associated markers (Nestin and NGFR) was revealed on melanospheres generated from melanoma cell lines and post-surgery specimens as well. However, no direct and unique correlation between any of these markers and the ability to form tumor in nude mice was evidenced. Taken together, these data indicate that melanomas do contain cells endowed with cancer stem cell properties (self renewal, clonogenicity, multipotency and tumor initiating capacity), although further studies are needed to elucidate molecular and biological features of this subset of cells composing the tumor mass.

Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr 197.

100th AACR Annual Meeting-- Apr 18-22, 2009; Denver, CO