Specific TP53 mutations in L3 domain alone (only in DFS) or in combination with specific Ki-ras mutations at codon 13 are associated with a worse prognosis in sporadic CRC.

Detection of Ki-Ras and TP53 mutation in plasma should be significantly related to disease recurrence. These data suggest that patients with a high risk of recurrence can be identified by means of the analysis of tumor-derived plasma DNA with the use of fairly non-invasive techniques.

The p16INK4a gene, localized within chromosome 9p21, has been identified as a cyclin-dependent kinase inhibitor and may negatively regulate the cell cycle acting as a tumor suppressor. Genetic alterations involving the 9p21 region are common in human cancers. A consecutive series of 64 untreated patients (median of follow up 53 months) undergoing surgical resection for locally advanced laryngeal squamous-cell carcinomas (LSCCs) has been studied prospectively. Our purpose was to investigate p16 alterations (9p21 allelic loss, hypermethylation and point mutations) and their possible association with clinico-pathological data and flow cytometric variables (DNA-ploidy and S-phase fraction (SPF)), and to determine the possible prognostic role of this gene in these tumors. PCR-based techniques were used for investigating 9p21 loss of heterozygosity (LOH) and methylation promoter status of the p16 gene. p16 mutations were detected by PCR-SSCP (single strand conformation polymorphism) and sequencing. 9p21 LOH was detected in 16/62 (26%) informative tumors, point mutations in 5% (3/64) and hypermethylation in 9% (6/64) of the cases. p16 alterations were significantly associated with high SPF and DNA-aneuploidy. By univariate analysis, poor histologic differentiation, stage IV, DNA-aneuploidy and p16 point mutations proved to be significantly related to quicker relapse, whereas these same factors, and in addition high SPF, 9p21 LOH and any p16 alterations were significantly related to shorter overall survival. By Cox proportional hazards analysis only histologic grade (G3) and p16 point mutations were independently related to both disease relapse and death. Our study has identified p16 point mutations as important biomolecular indicators in LSCCs.

The present study is the first BRCA1 disease-associated mutations analysis in Southern Italian families. The early age of onset of such tumors and the association with the HBOC familial profile could be two valid screening factors for the identification of BRCA1 mutation carriers. Finally, we identified a BRCA1 mutation with a possible founder effect.

The putative role of TP53 and p16 INK4A tumor suppressor genes and Ras oncogenes in the development and progression of salivary gland neoplasias was studied in 28 cases of pleomorphic adenomas (PA), 4 cases of cystic adenocarcinomas, and 1 case of carcinoma ex-PA. Genetic and epigenetic alterations in the above genes were analyzed by Polymerase Chain Reaction/Single Strand Conformational Polymorphism (PCR/SSCP) and sequencing and by Methylation Specific-PCR (MS-PCR). Mutations in TP53 were found in 14% (4/28) of PAs and in 60% (3/5) of carcinomas. Mutations in H-Ras and K-Ras were identified in 4% (1/28) and 7% (2/28) of PAs, respectively. Only 20% (1/5) of carcinomas screened displayed mutations in K-Ras. p16 INK4A promoter hypermethylation was found in 14% (4/28) of PAs and 100% (5/5) carcinomas. All genetic and epigenetic alterations were detected exclusively in the epithelial and transitional tumor components, and were absent in the mesenchymal parts. Our analysis suggests that TP53 mutations and p16 INK4A promoter methylation, but not alterations in the H-Ras and K-Ras genes, might be involved in the malignant progression of PA into carcinoma.