Loss of heterozygosity and methylation of p16 in renal cell carcinoma.

To investigate the possible role of genomic aberrations of chromosome 9p21 in the tumorigenesis of human renal cell carcinoma (RCC), 40 sporadic RCCs were studied using PCR analyses. The tumours were predominantly low stage and low grade. Loss of heterozygosity (LOH) was observed in nine of 39 informative cases, but no homozygous deletion was noticed. Hypermethylation of the promoter region of p16 occurred in eight of the 40 RCCs. No correlation was found between hypermethylation of the p16 gene and LOH on 9p21. A similar level of LOH and methylation was observed in the 40 RCCS regardless of histology, grade and stage. These results suggest that inactivation of p16 and the possibility of other unknown tumour suppressor genes located on other chromosomes could be involved in the pathogenesis of RCC.

[Loss of heterozygosity in the 9p21 region as an inactivation mechanism of the p16 suppressor gene]. / Pérdida de heterocigosidad en la región 9p21 como mecanismo de inactivación del gen supresor p16.

OBJECTIVE: To determine the loss of heterozygosity (LOH) on 9p21 (locus D9S1747) in patients with renal carcinoma by analysis of microsatellite polymorphisms. METHODS: 40 patients with sporadic renal cancer were studied. LOH on 9p21 was performed by analysis of microsatellite polymorphisms. RESULTS: 23.7% showed LOH on 9p21. No correlation was found between this genetic alteration and tumor features. CONCLUSIONS: LOH on 9p21 was found in 23.7% of the patients in this series. LOH was found in 26.9% of renal cell carcinomas, 25% of papillary carcinomas and 25% of Bellini duct carcinomas. LOH was not found in the other histological types.

Loss of heterozygosity on the short arm of chromosome 3 in renal cancer.

3% of human cancers are renal cell carcinomas (RCC). The most common chromosome abnormality found in this tumor is loss of heterozygosity (LOH) on the short arm of chromosome 3, which suggests that there must be one or more tumor suppressor genes between 3p14 and 3p21 near the VHL gene which play a relevant role in renal cancer development. DNA from normal and tumor tissue from 40 patients at various stages of RCC was analyzed for LOH at three microsatellites mapped to 3p (3p14.1-14.3; 3p21.2-21.3 and 3p25) by polymerase chain reaction). 42.5% of the tumors studied showed LOH on at least one locus. 30% showed LOH on only one locus; 5% on two loci and 7.5% on the three loci tested. LOH occurred only on nonpapillary tumors (p = 0.03). Interestingly, all the tumors with LOH on 3p21 were >/=25 mm (p = 0.04; relative risk 1.76, confidence interval: 1.3-2.3).

[5'CpG island methylation of the suppressor gene p16/CDKN2/MTS1 in renal carcinoma]. / Metilación de las islas 5'CpG del gen supresor p16/CDKN2/MTS1 en carcinoma renal.

OBJECTIVE: To determine the methylation status of the tumor suppressor gene p16 in patients with renal carcinoma by analysis of microsatellite polymorphisms. METHODS: 40 patients with sporadic renal cancer were studied. Tumor and normal tissue from each patient were tested for methylation status of the p16 gene by analysis of microsatellite polymorphisms. RESULTS: 20% showed methylation of p16. No correlation was found between this genetic alteration and tumor features. CONCLUSIONS: Methylation of p16 was found in 20% of the patients in this series. According to the analysis, 18.5% of renal cell carcinomas showed methylation, 50% of chromophobe cell carcinomas and 25% of carcinomas of Bellini's tubules. The rest of the histological types showed no methylation.

Prognostic value of the quantified expression of p185 in non-small cell lung cancer.

BACKGROUND: We sought to assess the relationship between tissue concentration of erb -b-2 or neu oncogene-encoded protein (p185(neu)) with overall survival in patients with non-small cell lung cancer. METHODS: Levels of protein p185(neu) were determined in 102 patients with the diagnosis of non-small cell lung cancer. Concentration of p185(neu) protein was determined by using enzyme immunoassay and evaluated by using several variables. The relative prognostic importance of this marker and its influence on other prognostic factors was evaluated by using the Cox regression model. RESULTS: The mean p185(neu) value in these samples was 250 +/- 200 U/mg (95% confidence interval, 210-290). This distinguished two groups within the tumoral population: those with less than 350 U/mg and those with 350 U/mg or greater (80th percentile). Multivariable analysis established an independent prognostic value for protein p185(neu). Patients with p185(neu) values of the 80th percentile or greater had a risk of death that was 2.11-fold (95% confidence interval, 1.10-4.05) that of patients with values of less than 350 U/mg (P =.03), and increases in the neu oncogene of 100 U/mg increased the probability of death by 17% (P =.02; 95% confidence interval, 1.04-1.31). CONCLUSION: This study shows that the p185(neu) expression is an objective and comparable variable for the assessment of phenotypic aggressivity in non-small cell lung cancer, and in the future, it could be included in daily clinical practice.

Use of possible synergistic expression of p53 and p185 as a prognostic tool for stage I non-small-cell lung cancer.

The possible interaction between the quantified overexpression of the oncoproteins p53 and p185 was evaluated. These proteins have already been independently defined as prognostic factors in non-small-cell lung cancer (NSCLC). p53 and p185 levels were determined in stage I patients (n = 40) from a sample of 102 NSCLC sufferers who underwent surgery for precocious disease during the period October 1991 to June 1994. The resected tumors were histologically classified and included 15 adenocarcinomas (37.5%), 1 large-cell carcinoma (2.5%), and 24 epidermoid (60%) carcinomas. The p53 concentration of tumor specimens was determined by luminescence immunoanalysis and was defined as positive if it was above the minimum value detectable by the method (0.01 ng/mg). The p185 protein was quantified by enzyme-linked immunoassay, and the 80th percentile of the frequency distribution was used as the reference cutoff value (348.8 U/mg). Survival and disease-free-survival (DFS) rates were estimated at 24 months after intervention. There were no significant differences in survival or DFS of patients with adenocarcinoma-type tumors for subjects with independent p185 values < 348.8 U/mg and those showing values >/= 348.8 U/mg. Neither were there differences observed between patients with positive and negative p53 values. In patients with epidermoid-type tumors the cumulative survival was significantly higher in p53-negative than in p53-positive patients (p = 0.03) and was also higher in patients with p185 levels < 348.8 U/mg than in those with values >/= 348.8 U/mg (p = 0.00001). These patients showed no significant differences with respect to recurrence rate. The possible synergistic behavior of p53 and p185 levels as a prognostic factor was evaluated in patients with epidermoid-type tumors. p53-negative and p53-positive patients were grouped according to a p185 level of less than or more than 348.8 U/mg. Significant differences were seen in both survival rates and DFS between groups. Individual analysis of relative risks showed an increased risk of death and greater recurrence rate in patients with p185 levels >/= 348.8 U/mg and a greater recurrence rate in patients with p53-positive values. Multivariate analysis established that the multiplicative, synergistic, prognostic effect of p53 and p185 was not significant. The existence of a significant, synergistic, prognostic effect of the p185 and p53 proteins in NSCLC could not be proven. However, a greater prognostic potential of the quantified overexpression of p185 with respect to that of p53 was established. An additive effect in the prognostic potential of both proteins was also observed (stratified analysis).

Expression of high p53 levels in colorectal cancer: a favourable prognostic factor.

The expression of p53 protein was examined in a series of 111 colorectal cancer adenocarcinomas with a long follow-up. A quantitative luminometric immunoassay (LIA) was used for the measurement of wild-type and mutant p53 protein in extracts from colorectal tumour cytosols, p53 being detected in 42% of the samples (range 0.0-52 ng (mg-1)). Using an arbitrary cut-off value of 2.7 ng mg(-1), 25% of the tumours were classified as manifesting high p53 levels. There was no association of p53 expression with patient age, sex, serum preoperative carcinoembryonic antigen (CEA) levels, tumour site and size, nodal status or TNM stage. Significant and independent correlation was found to exist between high p53 levels and prolonged disease-free survival (P = 0.05) at a median follow-up of 60 months. This survival advantage was most apparent among stage III cancer patients. The results from this study would suggest that expression of high p53 levels appear to be useful in selecting a group of colorectal cancer patients with a better prognosis.

[Prognostic value of heterozygosity loss in chromosome 3p in non-microcytic bronchogenic carcinoma]. / Valor pronóstico de la pérdida de heterozigosidad en el cromosoma 3p en el carcinoma broncogénico no microcítico.

BACKGROUND: Recent advances on carcinogenesis have led to the recognition of different patterns of behaviour of non-small cell lung cancers apart from those guided by the TNM staging system and the histologic subtype. The frequent genetic loss on chromosome 3p in all kinds of lung carcinoma leads to the suspect of the presence of a tumor suppressor gene located in that place. The aim of this work was to compare the different clinical features and evolution after treatment of the patients with non small cell lung carcinoma with and without loss of heterozygosity (LOH) on 3p. PATIENTS AND METHOD: Forty-five operated on non-small cell lung cancer patients were evaluated. The mean age was 64.4 years and all the patients were male. Seven patients had been previously treated for another epithelial neoplasm. 82.2% of the patients were heavy tobacco smokers. Most of the tumors (62.2%) were squamous cell carcinomas. Samples of tumoral and non tumoral lung tissue were immediately frozen after surgery. DNA from the tissue was extracted; then PCR amplification of microsatellites in regions 3p14 and 3p21 was performed. To determine the LOH in the regions analyzed a polyacrylamide gel electrophoresis was performed. RESULTS: Twenty-five percent of the informative samples for 3p14 and 21.9% for 3p21 showed LOH. There was an statistical relationship between the LOH on 3p14 and the history of tobacco smoking and the adenocarcinoma histologic subtype (p < 0.05). There was a higher number of relapses and a shorter disease-free interval in those patients harboring 3p21 LOH. CONCLUSIONS: LOH on 3p can be detected in non-small cell lung carcinoma. Patients with loss of heterozygosity on 3p21 have a worse evolution after a curative intended surgical resection.