Microsatellite instability in malignant melanoma.

Defective mismatch repair has been detected in human colorectal and endometrial carcinomas which exhibit microsatellite instability (MIN). The purpose of this study was to search for MIN in melanoma. Paraffin-embedded neoplastic and non-neoplastic control cells were obtained from 20 untreated individuals with cutaneous malignant melanoma. Breslow thickness ranged from 0.2-7.4 mm (mean 1.4). Cells were carefully scraped from glass slides so that tumor and control DNA could be isolated and then amplified by polymerase chain reaction (PCR) at seven separate microsatellites localized to specific chromosome regions: 1p22 (D1S187), 5q11.2-13.3 (D5S107), 6q21-23.3 (D6S357), 9p21 (IFNA), 11p15.2 (D11S861), 17p13.1 (D17S786), and 18q11 (D18S34). Heterozygosity indices were > or = 0.70. Loci from these chromosome regions were chosen because of cytogenetic abnormalities reported in melanoma (1p, 6q, 9p), location of common oncogenes (11p-HRAS, 17p-TP53), or use in other MIN studies (5q, 18q). Five individuals (25%) demonstrated MIN. There was no correlation with tissue thickness. One individual demonstrated MIN at two loci and one individual demonstrated loss of heterozygosity. The results indicate that MIN occurs in melanoma, albeit less frequently than reported in carcinomas.

Rapid analysis of estrogen and progesterone receptors using gel-exclusion high-performance liquid chromatography.

Estrogen and progesterone receptors prepared from mouse, rat, and human uteri, as well as from human breast cancers, have been characterized by gel-exclusion high-performance liquid chromatography. The qualitative relationships previously established by sedimentation analysis between the cytoplasmic [aggregated (approximately 8S), deaggregated (approximately 4S), and trypsinized (approximately 3.6S)] and nuclear (approximately 5S) forms of the rat uterine estrogen receptor were maintained by this technique. Differences in the partition of estrogen and progesterone receptors from the same species as well as interspecies differences in these receptors were reproducibly observed. Multiple forms of human estrogen and progesterone receptors could clearly be resolved in a single analysis and were distinct from serum steroid binding tissue contaminants. Separation analyses, performed at flow rates up to 2 mL min-1, were capable of resolving all receptor forms in 10--12 min with the column returning to base line in 25 min. With this exclusion gel column (TSK-G3000SW) as a background upon which to reference different receptor forms, eight distinct partitions or elution positions have been enumerated. This approach has considerable promise for the rapid characterization of different forms of steroid-receptor proteins. Moreover, it should provide a critical advantage in minimizing the opportunities for receptor modification during separation analysis and in maximizing the opportunity to study short-lived interactions between receptors and physiologic or pharmacologic ligands.