Comparative genome hybridization analysis of laser-capture microdissected in situ melanoma

The progression of melanoma occurs through discrete stages with known clinical and histologic features. Although many molecular events that occur during the progression of invasive and metastatic melanomas have been elucidated, there is limited knowledge of genetic changes that occur in the earliest stages of melanoma development. In this pilot study, we investigated genetic changes that happen in in situ melanoma so that we can better understand early melanoma development.

DNA was extracted from five laser-capture microdissected Clark's level III melanomas, five in situ melanomas and five compound nevi all from sun exposed skin. Array-based comparative genomic hybridization was performed using Agilent 44 K platform.

The group of Clark's level III melanomas was characterized with multiple large deletions and duplications. In the group of in situ melanoma, deletions and duplications were limited in size. Deletions in in situ melanomas were present only on chromosomes 13q and 16q. Compound nevi did not show any significant chromosomal aberrations.

In situ melanomas show characteristic chromosomal aberrations that are limited compared to melanomas that invade the dermis. Deletion of 13q found in in situ melanomas, which encompass the Rb1 tumor suppressor gene, might be one of the first events in the development of melanoma.