Molecular characterization of novel melanoma cell lines.

We isolated two novel cell lines from different types of sporadic human malignant melanoma: the hmel1 line was obtained from a melanoma skin metastasis and the hmel9 cell line from a primary superficial spreading melanoma. The karyotype and pigmentation parameters were assessed in these cell lines. Cytogenetic analysis in early stages of culture revealed that both cell lines had chromosome instability and simultaneous growth of heteroploid subpopulations. The molecular analysis of some genes involved in melanoma showed that both cell lines harbor BRAF mutations. The unpigmented hmel1 and the pigmented hmel9 lines were found to express the tyrosinase gene. The tyrosine hydroxylase activity was detectable only in hmel9 cells and practically absent in the hmel1 cell line. This activity was found to be correlated with the relative tyrosinase protein amount in both melanoma cell lines. The biological behaviour in the two melanoma cell lines, derived from two different types of melanoma lesions displaying distinct clinical and histopathological features, confirms the heterogeneous characteristics of sporadic melanoma. Similarities and/or differences between cell lines extracted from different melanoma cases could be useful in the future for diagnostic, prognostic and therapeutic purposes.