Molecular Cytogenetic Evaluation of 10 Uveal Melanoma Cell Lines

Uveal melanoma is the most common intraocular tumor in adults and often results in unilateral blindness and/or death. Previous cytogenetic characterizations of this tumor consistently revealed chromosomal abnormalities involving chromosomes 3, 6, and 8; reports of other abnormalities vary in frequency. We defined cytogenetic abnormalities of this tumor using complementary in situ hybridization techniques on 10 uveal melanoma cell lines. Synthesis of comparative genomic hybridization (CGH) and spectral karyotyping (SKY) results revealed that chromosomal rearrangement is involved in DNA sequence copy number abnormalities throughout the genome, but monosomy 3 was not found. Monosomy 3 is thought to be a significant prognostic indicator, so its absence was investigated further. Fluorescence in situ hybridization (FISH) for chromosome 3 revealed approximately 1 centromere signal per cell, but probes for 3p and 3q revealed multiple telomere signals per cell, suggesting chromosomal rearrangement without whole-chromosome loss. Based on combined CGH, SKY, and FISH data, we propose that chromosome 3 is more frequently involved in chromosomal rearrangements than whole-chromosome loss in uveal melanoma. Future approaches should be designed to confirm and enhance the resolution of regions of imbalance in primary tumors. Once identified, conserved chromosomal alterations that contribute to uveal melanoma may reveal the underlying aspects of uveal melanoma onset, metastasis and resistance to current treatment modalities.