Purpose The prevalence of BRAF, NRAS, and p16CDKN2A mutations during melanoma progression remains inconclusive. We investigated the prevalence and distribution of mutations in these genes in different melanoma tissues. Patients and Methods In all, 291 tumor tissues from 132 patients with melanoma were screened. Paired samples of primary melanomas (n = 102) and synchronous or asynchronous metastases from the same patients (n = 165) were included. Tissue samples underwent mutation analysis (automated DNA sequencing). Secondary lesions included lymph nodes (n = 84), and skin (n = 36), visceral (n = 25), and brain (n = 44) sites. Results BRAF/NRAS mutations were identified in 58% of primary melanomas (43% BRAF; 15% NRAS); 62% in lymph nodes, 61% subcutaneous, 56% visceral, and 70% in brain sites. Mutations were observed in 63% of metastases (48% BRAF; 15% NRAS), a nonsignificant increase in mutation frequency after progression from primary melanoma. Of the paired samples, lymph nodes (93% consistency) and visceral metastases (96% consistency) presented a highly similar distribution of BRAF/NRAS mutations versus primary melanomas, with a significantly less consistent pattern in brain (80%) and skin metastases (75%). This suggests that independent subclones are generated in some patients. p16CDKN2A mutations were identified in 7% and 14% of primary melanomas and metastases, with a low consistency (31%) between secondary and primary tumor samples. Conclusion In the era of targeted therapies, assessment of the spectrum and distribution of alterations in molecular targets among patients with melanoma is needed. Our findings about the prevalence of BRAF/NRAS/p16CDKN2A mutations in paired tumor lesions from patients with melanoma may be useful in the management of this disease.

Molecular mechanisms involved in pathogenesis of malignant melanoma have been widely studied and novel therapeutic treatments developed in recent past years. Molecular targets for therapy have mostly been recognized in the RAS–RAF–MEK–ERK and PI3K–AKT signaling pathways; small-molecule inhibitors were drawn to specifically target key kinases. Unfortunately, these targeted drugs may display intrinsic or acquired resistance and various evidences suggest that inhibition of a single effector of the signal transduction cascades involved in melanoma pathogenesis may be ineffective in blocking the tumor growth. In this sense, a wider comprehension of the multiple molecular alterations accounting for either response or resistance to treatments with targeted inhibitors may be helpful in assessing, which is the most effective combination of such therapies. In the present review, we summarize the known molecular mechanisms underlying either intrinsic and acquired drug resistance either alternative roads to melanoma pathogenesis, which may become targets for innovative anticancer approaches.

We describe a patient with typical clinical features of the fragile X syndrome, but without cytogenetic expression of the fragile X or an amplified CCG trinucleotide repeat fragment. The patient has a previously uncharacterized submicroscopic deletion encompassing the CCG repeat, the entire FMR1 gene and about 2.5 megabases of flanking sequences. This finding confirms that the fragile X phenotype can exist, without amplification of the CCG repeat or cytogenetic expression of the fragile X, and that fragile X syndrome is a genetically homogeneous disorder involving FMR1. We also found random X-inactivation in the mother of the patient who was shown to be a carrier of this deletion.

Purpose of ReviewConventional clinico-pathological features in melanoma patients should be integrated with new molecular diagnostic, predictive, and prognostic factors coming from the expanding genomic profiles. Cutaneous melanoma (CM), even differing in biological behavior according to sun-exposure levels on the skin areas where it arises, is molecularly heterogeneous. The next-generation sequencing (NGS) approaches are providing data on mutation landscapes in driver genes that may account for distinct pathogenetic mechanisms and pathways. The purpose was to group and classify all somatic driver mutations observed in the main NGS-based studies.Recent FindingsWhole exome and whole genome sequencing approaches have provided data on spectrum and distribution of genetic and genomic alterations as well as allowed to discover new cancer genes underlying CM pathogenesis.SummaryAfter evaluating the mutational status in a cohort of 686 CM cases from the most representative NGS studies, three molecular CM subtypes were proposed: BRAFmut, RASmut, and non-BRAFmut/non-RASmut.

Allelic deletions, which are suggestive for the presence of tumor suppressor genes, represent a common event in endometrial cancer (EC). Previous loss-of-heterozygosity studies for human chromosome 10q identified a candidate deletion interval at 10q25-q26, which we further narrowed to a 160-kb region at 10q26, bounded by markers D10S1236 and WIAF3299. Using a positional candidate approach, we identified three alternative transcripts of a novel human gene, CASC2 (cancer susceptibility candidate 2; formely C10orf5). One of such transcripts, CASC2a, encodes a short protein of 102 amino acids with no similarity to any other known gene product. Three (7%) CASC2a mutations were identified in tumor DNA from 44 EC patients. While c.-156G>T and c.22C>T (p.Pro8Ser) are sequence variants with unknown functional significance, c.84delA is a mutation with a truncation effect on the predicted protein (p. Asn28fsX50). Expression studies by real-time RT-PCR on several normal and tumor cells revealed that CASC2a mRNA is downregulated in cancer, suggesting that it may act as a potential tumor suppressor gene. The very low mutation rate seems to also indicate that inactivation of CASC2a might probably be due to mechanisms different from genetic alterations.

To elucidate the function of the FMR1 gene, we applied RNA in situ hybridization to cryosections of mice from different developmental stages. The murine Fmr-1 was found transcribed in a ubiquitous manner with an expression pattern similar to glyceraldehyd phosphate dehydrogenase, Gapdh, which was used as a control gene. A significant difference in the Fmr-1 expression pattern, however, was markedly enhanced expression specifically confined to the testis and the fetal ovary. In the immature and mature testis an elevated level of Fmr-1 expression is found in type A1 spermatogonia. Expression in the testis is observed in fetal life, reaches the highest level in the immature testis, and declines early in adult life. In the mature ovary no specific Fmr-1 expression signal was found but enhanced levels were seen in the fetal ovary. At this developmental stage proliferation of oogonia takes place. It is suggested that FMR1 serves a special function during germ cell proliferation in males and females. These findings are discussed in the light of the current observation that fragile X patients produce only sperm with a premutation sized allele. Two hypotheses are put forward: (1) In males lack of FMR1 function results in a premeiotic defect preventing spermatogonia with a full mutation to reach meiosis. A fragile X mutation can be passed on to offsprings only as a premutation (selection hypothesis). (2) Transition of a premutation allele to full mutation occurs in a postzygotic stage after separation of the germ line and is restricted to soma cells (restriction hypothesis). Expression of FMR1 in proliferating germ cells is in line with both hypothesis.

The FMR1 gene, associated with fragile X syndrome, has recently been cloned and the sequence of partial cDNA clones is known. We have determined additional cDNA sequences both at the 5' and 3' end. We have characterized the expressed gene by means of RT-PCR in various tissues and have found that alternative splicing takes place in the FMR1 gene, which does not seem to be tissue specific. When the different alternative splicing events are combined, 12 distinct mRNA products could result from FMR1 expression in each tested tissue. In all these transcripts the open reading frame is maintained until the same stop codon. At the 3' end alternative use of polyadenylation signals is found. The alternative splicing allows functional diversity of the FMR-1 gene. Whether all the possible proteins will be synthesized and whether they will be functionally active has to be determined.

Cutaneous melanoma is a common and aggressive human skin cancers. Much is actually known about the molecular mechanisms underlying melanoma pathogenesis. The aim of the study was to evaluate any possible correlation between mutations in main growth-controlling genes (BRAF, NRAS, CDKN2A) and copy number variations in frequently amplified candidate genes (MITF, EGFR, CCND1, cMET, and cKIT) during melanoma initiation and progression.A large series of primary and secondary melanoma tissue samples (N = 274) from 232 consecutively-collected patients of Italian origin as well as 32 tumor cell lines derived from primary and metastatic melanomas underwent mutation screening and fluorescence in situ hybridization (FISH) analysis. Overall, BRAF, NRAS, and CDKN2A were found mutated in 62.5%, 12.5% and 59% cell lines and in 47%, 16%, 12% tumor tissues, respectively. Quite identical mutation patterns between primary tumors and metastatic lesions were found for BRAF and NRAS genes; mutations of CDKN2A gene appeared to be instead selected during tumor progression. In cell lines, high rates of gene amplifications were observed (varying from 12.5% for cKIT to 50% for MITF); vast majority of cell lines (75%) presented at least one amplified gene. Conversely, prevalence of gene amplification was significantly and progressively decreasing in melanoma metastases (12%) and primary melanomas (4%). Our findings suggest that gene amplifications may be acquired during the late phases of melanoma evolution and mostly act as “passenger” or “non-causative” alterations.