Aberrant methylation within RUNX3 CpG island associated with the nuclear and mitochondrial microsatellite instability in sporadic gastric cancers. Results of a GOIM (Gruppo Oncologico dell'Italia Meridionale) prospective study.

BACKGROUND: Gastric cancer (GC) development is a multistep process, during which numerous alterations accumulate in nuclear and mitochondrial DNA. A deficiency of repair machinery brings about an accumulation of errors introduced within simple repetitive microsatellite sequences during replication of DNA. Aberrant methylation is related to microsatellite instability (MSI) by the silencing of the hMLH1 gene. The aim of this study is to investigate a possible relationship between the RUNX3 promoter methylation, nuclear microsatellite instability (nMSI) and mitochondrial microsatellite instability (mtMSI), in order to clarify its biological role in GC. PATIENTS AND METHODS: nMSI and mtMSI were evaluated in a consecutive series of 100 GC patients. For the analysis of the nMSI, we followed the National Cancer Institute guidelines. mtMSI was assessed by analyzing a portion of the displacement-loop region. The aberrant methylation of RUNX3 was analyzed in 40 GC patients by methylation-specific PCR. RESULTS: Overall, 55% of GC demonstrated methylation of the RUNX3 promoter; 82% of GC was classified as stable microsatellite instability, 5% as low-level microsatellite instability and 13% as high-level microsatellite instability (MSI-H); mtMSI was detected in 11% of GC. A significant association was found between mtMSI and tumor-node-metastasis staging, furthermore an interesting association between MSI-H status, mtMSI and RUNX3 methylation. CONCLUSION: These data suggest that RUNX3 is an important target of methylation in the evolution of mtMSI and nMSI-H GC.

Aurora-A overexpression as an early marker of reflux-related columnar mucosa and Barrett's oesophagus.

BACKGROUND: The development of oesophageal adenocarcinoma is generally closely associated with the presence of a specialised intestinal-type epithelium such as that found in Barrett's oesophagus (BO). A particular histological condition is when the distal oesophagus showing cardiac and/or fundic mucosa without intestinal metaplasia cannot be defined as 'Barrett's mucosa' [condition that we call 'columnar-lined oesophagus' (CLO)] and up till now, there has been no agreement in literature about the management of this condition. Aurora-A overexpression leads to centrosome amplification, chromosomal instability and aneuploidy in mammalian cells. PATIENTS AND METHODS: A prospective study was carried out on 28 consecutive patients who presented columnar mucosa above the gastro-oesophageal junction (GOJ) at endoscopy. As controls, two more biopsies were obtained, one on the normal-appearing squamous oesophagus above the GOJ, as far as possible from the columnar mucosa (controls A), and one taken 1 cm below the GOJ (controls B). The Aurora-A and p53 expression levels were analysed respectively by Quantitative Real Time PCR and immunohistochemistry. RESULTS: Twelve patients were affected by BO (43%) while the other 16 patients (57%) had a CLO. Nine of 28 (32%) cases were focally positive for p53 immunostaining. All the BO/CLO samples were positive for the Aurora-A transcript with regard to controls. Furthermore, 13 of 28 (46%) cases showed overexpression (above the median for the whole group). CONCLUSION: Due to the low number of cases, we are not at present able to state that statistically significant quantitative differences in Aurora-A messenger RNA expression exist between CLO and BO cases with and without dysplasia and p53-positive immunostaining. Further studies on a larger number of cases with a follow-up period are necessary in order to establish the risk of progression and the correct management of these subjects.

Significance of P16INK4A hypermethylation gene in primary head/neck and colorectal tumors: it is a specific tissue event? Results of a 3-year GOIM (Gruppo Oncologico dell'Italia Meridionale) prospective study.

BACKGROUND: Methylation of the p16 promoter is one of the most frequent mechanisms of gene inactivation; its incidence is extremely variable according to the type of tumor involved. Our purpose was to analyze the hypermethylation of the p16 promoter in laryngeal squamous cell carcinomas (LSCC), salivary gland (SG) tumors and in colorectal cancer (CRC), to detect any possible association with the clinicopathological features and to determine the prognostic significance of the p16 gene in the tumors analyzed. PATIENTS AND METHODS: The hypermethylation of the p16 promoter was prospectively analyzed, by MSP, in a consecutive series of 64 locally advanced LSCC patients, in a consecutive series of 33 SG tumor patients and in a consecutive series of 66 sporadic CRC patients. RESULTS: Hypermethylation was observed in 9% of the LSCC cases, in all cases of SG cancer and in 21% of the CRC cases. No significant association was observed between p16 hypermethylation and clinicopathological variables in all the tissue samples analyzed. Moreover at univariate analysis p16 mutations were not independently related at disease relapse and death in LSCC and CRC. CONCLUSIONS: The results of this study suggest that the lack of p16 function could happen in advanced stage of SG tumors.