Chromosomal imbalances in primary and metastatic melanomas revealed by comparative genomic hybridization

Abstract

Characteristic genetic changes underlying the metastatic progression of malignant melanoma is incompletely understood. The goal of our study was to explore specific chromosomal alterations associated with the aggressive behavior of this neoplasm. Comparative genomic hybridization was performed to screen and compare genomic imbalances present in primary and metastatic melanomas. Sixteen primary and 12 metastatic specimens were analyzed. We found that the pattern of chromosomal aberrations is similar in the two subgroups; however, alterations present only in primary and/or metastatic tumors were also discovered. The mean number of genetic changes was 6.3 (range 1-14) in primary and 7.8 (range 1-16) in metastatic lesions. Frequent losses involved 9p and 10q, whereas gains most often occurred at 1q, 6p, 7q, and 8q. Distinct, high-level amplifications were mapped to 1p12-p21 and 1p22-p31 in both tumor types.

Involvement of overexpressed wild-type BRAF in the growth of malignant melanoma cell lines

“…Comparative genomic hybridization (CGH) (Kallioniemi et al, 1992) has proven to be an useful technique for identifying novel regions of amplification. Although CGH studies have revealed a variety of chromosomal aberrations in MM (Bastian et al, 1998;Balazs et al, 2001), only one gene, CCND1, within an amplicon at 11q13, has been identified so far as a target oncogene in acral melanomas (Sauter et al, 2002).…”

Chromosomal imbalances in laryngeal and hypopharyngeal cancers detected by comparative genomic hybridization

“…Imprint preparations were made from fresh or frozen tissues and fixed as described previously (29). Six-micron sections were stained with hematoxylin and eosin for morphologic examination.…”

“…CGH experiments were carried out as described previously (29). Briefly, the hybridization mixture, consisting of 200 ng of each labeled DNA and 20 mg of unlabeled human Cot-1 DNA (Life Technologies, Gaithersburg, MD, USA), was precipitated and dissolved in hybridization mixture and denatured at 73°C (3-5 min) immediately before applying onto normal metaphase spreads (Vysis Inc.).…”

“…Only images showing uniform high-intensity fluorescence were analyzed. Image analysis and interpretation of CGH data were performed as described in detail previously (29). Briefly, a multicolor quantitative image processing system (ISIS, MetaSystems GmbH, Altussheim, Germany) connected to a Zeiss fluorescence microscope was used for data acquisition and for evaluation of the CGH experiments.…”

“…The lower and upper threshold values were defined as described. Gain of chromosomal regions was assumed at a ratio greater than 1.15 and loss was defined at ratio less than 0.85 (29). Amplifications were assumed only when the green-to-red ratio was above 1.5 or visual inspection revealed a bright and distinct green fluorescent signal at a subregion of the homologue chromosome.…”