Molecular detection of TP53, Ki-Ras and p16INK4A promoter methylation in plasma of patients with colorectal cancer and its association with prognosis. Results of a 3-year GOIM (Gruppo Oncologico dell'Italia Meridionale) prospective study

BACKGROUND

Despite the improvement in detection and surgical therapy in the last years, the outcome of patients affected by colorectal carcinoma (CRC) remains limited by metastatic relapse. The aim of this study was to investigate the presence of free tumor DNA in the plasma of CRC patients in order to understand its possible prognostic role.

PATIENTS AND METHODS

Ki-Ras, TP53 mutations and p16(INK4A) methylation status were prospectively evaluated in tumor tissues and plasma of 66 CRC patients.

RESULTS

In 50 of the 66 primitive tumor cases (76%) at least one significant alteration was identified in Ki-Ras and/or TP53 and/or p16(INK4A) genes. Eighteen of the 50 patients presented the same alteration both in the plasma and in the tumor tissue. At univariate analysis, Ki-Ras mutations proved to be significantly related to quicker relapse (P <0.01), whereas only a trend towards statistical significance (P = 0.083) was observed for the TP53 mutations

CONCLUSIONS

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.

Detection and quantification of mammaglobin in the blood of breast cancer patients: can it be useful as a potential clinical marker? Preliminary results of a GOIM (Gruppo Oncologico dell'Italia Meridionale) prospective study

BACKGROUND

Mammaglobin is expressed mainly in mammary tissue, overexpressed in breast cancer (BC) and rarely in other tissue. The aim of this study was to assess the sensitivity and specificity of transcript MGB1 detection and to evaluate the role of MGB1 as potential clinical marker for the detection of disseminated cancer cells in the blood of BC patients.

PATIENTS AND METHODS

A consecutive series of 23 BC tissues, 36 peripheral blood BC samples and 35 healthy peripheral blood samples was prospectively recruited to investigate MGB1 expression by means of a quantitative Real Time RT-PCR assay.

RESULTS

MGB1 overexpression in tissue samples of BC patients is significantly associated only with high level of Ki67 (P <0.05). None of the samples from peripheral blood of 35 healthy female individuals were positive for MGB1 transcript. In contrast MGB1 mRNA expression was detected in three of 36 (8%) peripheral blood of BC patients.

CONCLUSIONS

Our preliminary results demonstrate that the detection of MGB1 transcript in peripheral blood of BC patients was specific but with low sensitivity. MGB1 overexpression by itself or in combination with Ki67 might be considered an index of BC progression.

Y179C, F486L and N550H are BRCA1 variants that may be associated with breast cancer in a Sicilian family: results of a 5-year GOIM (Gruppo Oncologico dell'Italia Meridionale) prospective study

BACKGROUND

Over 600 different pathogenic mutations have been identified in the BRCA1 gene. Nevertheless, numerous missense mutations of unknown biological function still exist. Understanding of biological significance of these mutations should help in genetic counselling to carriers and their families.

PATIENTS AND METHODS

A total of 104 patients with breast and/or ovarian cancer whose genetic counselling answered the criteria of the American Society of Clinical Oncology (ASCO 2003), were prospectively screened for mutations in all coding exons of the BRCA1 gene by automatic direct sequencing.

RESULTS

During these mutational screening procedures one case presented three mutations classified in the Breast Cancer Information Core Database as unknown variants. These were 655A/G found in exon 8 of BRCA1, 1575T/C and 1767A/C found in exon 11 of the same gene. The identification of the three unknown variants in the proband (16SIRIO) and in her mother and sister indicates that such alterations exist in cis.

CONCLUSIONS

Our results suggest that the charge and stechiometry variations determined by the changes in the amino acids Y179C, F486L and N550H might produce an effect on the conformation of the protein and, consequently, on its function.

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.

4843delC of the BRCA1 gene is a possible founder mutation in Southern Italy (Sicily)

BACKGROUND

The frequency and the type of BRCA1 mutations vary widely and might have different geographic and ethnic distribution. Most of these alterations are generally found in isolated populations as a consequence of the founder effect. The object of this study was to determine whether 4843delC, a deleterious mutation of the BRCA1 gene, might be due to a founder effect originating in the Sicilian region of Italy. This mutation was described by us for the first time and identified in two unrelated Sicilian families with hereditary breast/ovarian cancer. The two families were from the same geographical area (south-western area of Palermo, Sicily). The homogeneity of the ethnic group of the two families and the Single Nucleotide Polymorphism (SNPs) analysis of probands led us to perform a study of the allelotype of the various members.

PATIENTS AND METHODS

The analysis of the haplotype of the probands and of several family members was conducted by means of a study of the highly polymorphic microsatellites within or flanking the BRCA1 gene.

RESULTS

This analysis revealed the presence of a common allele associated with the mutation.

CONCLUSIONS

We therefore conclude that 4843delC of the BRCA1 gene is a possible founder mutation in the Sicilian population.