Our molecular and clinical results are in agreement with previous findings but provide additional information into the biologic mechanisms involved in HR-HPV oropharyngeal cancer in comparison to HPV-negative tumors. According to the reduced risk of relapse and second tumors associated with HR-HPV positivity of oropharyngeal cancer, the therapeutic strategy and follow-up procedures should be reviewed.

To evaluate the mutational profiles associated with BRAF mutations in human melanoma, we have studied BRAF, RAS, PTEN, TP53, CDKN2A and CDK4 genes and their expression in melanoma lesions. Owing to the lack of sufficient material from fresh specimens, we employed short-term cell lines obtained from melanoma biopsies. In all, 41 melanoma obtained from eight primary lesions, 20 nodal, 11 cutaneous and two visceral metastases from patients with sporadic (n ¼ 31), familial (n ¼ 4) and multiple melanoma (n ¼ 2) were analysed. The results revealed novel missense mutations in the BRAF, PTEN, CDKN2A and CDK4 genes. Overall, activating mutations of BRAF and loss of functional p16 and ARF were detected in the majority of melanomas (29/41, 36/41 and 29/41, respectively), while PTEN alterations/loss, NRAS and TP53 mutations occurred less frequently (6/41, 6/41 and 10/41, respectively). In the resulting 12 mutational profiles, p16/ARF loss associated with mutated BRAF V599E was the most represented (n ¼ 15). In addition, TP53 and PTEN mutations were always accompanied with BRAF alterations, while PTEN loss was found in association with CDKN2A or TP53 mutations in the absence of BRAF activation. The p16/ARFD þ BRAF/ RAS profile was significantly associated with a longer survival, while complex mutational profiles were detected in highly aggressive disease and poor survival. These data support the existence of several molecularly defined melanoma groups which likely reflect different clinical/ biological behaviour, thus suggesting that a more extensive molecular classification of melanoma would significantly impact its clinical management.

Purpose: The issue of whether colon and rectal cancer should be considered as a single entity or two distinct entities is still debated, and there is a need to improve studies addressing the heterogeneity of the pathogenetic pathway leading to sporadic colorectal cancers (SCRCs) as well as to identify biological and/or molecular differences between colon and rectal cancers.Experimental Design: Specimens of SCRCs were analyzed for somatic mutations in APC, K-ras, and TP53 genes and loss-of-heterozygosity of chromosome 18.Results: Eleven SCRCs showed microsatellite instability. APC mutation frequency was significantly lower in microsatellite instability (MIN؉) than in MIN؊ SCRCs. All MIN؊ SCRCs showed ␤-catenin overexpression. A combined analysis of the biomarkers revealed two pathways mainly represented by MIN؊ SCRCs and differently followed on the basis of tumor location, APC-K-ras-TP53-Ch18q and APC-TP53-Ch18q.Conclusions: The APC-␤-catenin pathway is inactivated in MIN؊ SCRCs and represents the first hit of SCRC development. Two preferential pathways followed by SCRCs occur, one K-ras dependent, in agreement with the Fearon and Vogelstein model, and the other K-ras independent. Significant differences between colon and rectal tumors occur in our series of MIN؊ SCRCs. The different pathways observed and their distribution can be summarized as follows: (a) K-ras mutations were more commonly detected in colon than in rectum; (b) the number of mutations detected was significantly higher in colon than in rectal tumors; and (c) a mutational pattern restricted to the APC gene was more common in rectal than in colon tumors. This molecular characterization can be translated into a clinical setting to improve diagnosis and to direct a rationale pharmacological treatment.

Purpose:The aim of this study was to acquire further insights into the pathogenetic pathways of head and neck squamous cell carcinomas (HNSCC) that may be useful for identifying new biomarkers instrumental in developing more specific treatment approaches. Experimental Design: Cell cycle regulators and epidermal growth factor receptor (EGFR) and BRAF genes were analyzed in a series of 90 oropharyngeal SCCs of a cohort of surgically treated patients from a single institution, and the results were matched with the presence of high-risk human papillomavirus (HR-HPV) DNA and theTP53 status. Results: At least four distinct groups of tumors were identified sharing a common histology but displaying different molecular/cytogenetic patterns: (a) 19% were HPV-positive SCCs whose lack of alterations of the investigated genes could explain their particular natural history, which requires less aggressive treatment; (b) 37% were HPV-negative SCCs carryingTP53 mutations, which may be more effectively treated by drugs acting through p53-independent apoptosis; (c) 34% were HPV-negative SCCs carrying wild-typeTP53 and loss of 9p21 (p16 INK4a and p15 INK4b) and/or cyclin D1overexpression that justify treatment with DNA-damaging drugs followed by cell cycle inhibitors; and (d) 10% were HPV-negative lacking tumor suppressor genes and cell cycle alterations.The second, third, and fourth groups also showed an increased copy number of EGFR and chromosome 7 (43%) that might justify the additional or alternative use of EGFR inhibitors. Conclusions: Our findings suggest that assessing HPV, TP53, 9p21, and EGFR status may be crucial to finding more tailored and beneficial treatments for oropharyngeal SCCs.Head and neck squamous cell carcinomas (HNSCC) are usually treated with surgery and/or radiotherapy, and advanced cases may be also treated with concomitant chemotherapy and radiotherapy. However, a greater understanding of the complex process leading to the transformation and maintenance of the malignant phenotype of HNSCC might help in the identification of diagnostic, prognostic, or predictive markers as well as of new therapeutic targets.Despite their shared histology, the presence or absence of high-risk human papillomavirus (HR-HPV) identifies two distinct HNSCC entities with different clinical properties and genetic-molecular patterns. Clinically, the tumors with integrated viral DNA show a more favorable outcome than those that are HR-HPV negative (1). At molecular level, the HR-HPVpositive HNSCCs are characterized by the lack of p16INK4a gene deletion coupled with p16 protein expression (2) and a unique gene expression profile (3), with a decreased occurrence of TP53 mutations, cyclin D up-regulation/amplification, 14-3-3j and RASSF1A promoter methylation (4), and loss of heterozygosity at 17p, 9p, and 3p (5, 6). These latter are common alterations in patients with HPV-negative HNSCCs.Clinical behavior of HPV-negative HNSCCs is heterogeneous, and it is warranted to better characterized this gray zone. The most frequent mo...

SUMMARY:Karyotypic complexities associated with frequent loss or rearrangement of a number of chromosome arms, deletions, and mutations affecting the TP53 region, and molecular alterations of the INK4A gene have been reported in sporadic and/or neurofibromatosis type I (NF1)-related malignant peripheral nerve sheath tumors (MPNSTs). However, no investigations addressing possible different pathogenetic pathways in sporadic and NF1-associated MPNSTs have been reported. This lack is unexpected because, despite similar morphologic and immunophenotypic features, NF1-related cases are, by definition, associated with NF1 gene defects. Thus, we investigated the occurrence of TP53 and p16INK4A gene deregulation and the presence of microsatellite alterations at markers located at 17p, 17q, 9p21, 22q, 11q, 1p, or 2q loci in MPNSTs and neurofibromas either related (14 cases) or unrelated (14 cases) to NF1. Our results indicate that, in MPNSTs, p16INK4A inactivation almost equally affects both groups. However, TP53 mutations and loss of heterozygosity involving the TP53 locus (43% versus 9%), and p53 wild type overexpression, related or not to mdm2 overexpression (71% versus 25%), seem to mainly be restricted to sporadic MPNSTs. In NF1-associated MPNSTs, our microsatellite results are consistent with the occurrence of somatic inactivation by loss of heterozygosity of the second NF1 allele. (Lab Invest 2001, 81:833-844).