Association between p53 mutation and clinicopathological features of non-small cell lung cancer

Impact of glutathione S transferases P1 (Ile105Val) variants on the risk of GSTp, phosphorylated c-Jun kinase, and P53 phenotypic expression and their implications on overall survival outcomes in non-small cell lung cancer patients treated with chemotherapy

AIM

This study focused on GST-M1, T1 null, and P1 Ile105Val variant genotypes associated with the risk of altered expression of GSTp, pJNK, and P53 in NSCLC patients. These markers and overall survival (OS) were correlated with a key set of clinicopathological characteristics.

METHODS

Genotyping of GST- M1, T1 (+/-), and P1 (Ile105Val) was performed using PCR-RFLP.The expression of GSTp, pJNK, and P53 phenotypes was assessed by immunohistochemistry. The Spearman test was used to examine the correlation between GSTp, pJNK, and P53. Kaplan-Meier test was used for OS analysis.

RESULTS

GSTP1 Val/Val and Ile/Val genotypes notably increased GSTp expression by 1.8 and 1.7 fold, respectively (p = 0.04,p = 0.06). GSTP1 Val/Val and Ile/Val genotypes considerably reduced P53 expression by 0.61 and 0.57 fold, respectively (p = 0.03& p = 0.05), respectively. GSTp, pJNK, and P53 were significantly co-expressed (p < 0.001). GSTp and pJNK expression showed a moderate negative correlation (ρ = -0.32, p = 0.046). In contrast, GSTp and P53 expression exhibited a strong negative correlation (ρ = -0.53, p < 0.0001). There was no correlation between P53 and pJNK expression(ρ = 0.07, p = 0.54). The patient's median OS was 8.9 months, and it was significantly related to pack-years, stage, metastasis, and GSTM1(-/-) genotypes (p > 0.05). SQCLC showed poor OS than ADC (5.7 months vs.9.1 months, p = 0.2). Stage IV and metastasis significantly reduced the OS (p = 0.001). The tumour size and lymph nodes reflected poor OS (p = 0.07&p = 0.06). Gemcitabine+Cisplatin and Gefitinib showed a slightly higher rate of survival (9.3 months and 8.1 months) than Pemtrexe+Cisplatin treatment (7.0 months,p = 0.8). Multivariate analysis revealed that pack-years and GSTp were independent predictors for OS (p = 0.03).

CONCLUSION

GSTp, pJNK, and P53 showed interconnected cascading. Age, pack-year, stage, and GSTp were found to be significant predictive factors for OS.Pack-years, GSTp independent OS predictor.

Coalterations of p53 and PTEN tumor suppressor genes in non-small cell lung carcinoma patients

The inactivation of p53 and PTEN tumor suppressor genes is a common genetic event in lung cancer. However, data on the effect of the joint inactivation of tumor-suppressor genes in non-small cell lung carcinoma (NSCLC) are lacking. The purpose of this study was to investigate the alterations in PTEN and p53 genes, as well as to evaluate their mutual role in NSCLC pathogenesis and their impact on survival rate. To that end, polymerase chain reaction single-strand conformational polymorphism (PCR-SSCP), sequencing, methylation-specific PCR, and fragment analysis were used. The results obtained were correlated with clinicopathologic parameters, the level of genomic instability, and patient survival. Overall, 13% of specimens had aberrant p53 only, 13% had inactive PTEN only, and 50% of samples had both genes altered. Correlation analyses showed that the mutual inactivation of p53 and PTEN was a frequent event that was associated significantly with the increased level of genomic instability and lymph node invasion implying their synergistic effect in promoting metastatic phenotype of this kind of cancer. In addition, our results revealed a significant association of joint alterations of these genes with dramatically shortened survival indicating that aberrant p53 and PTEN could be used as an adverse prognostic factor for NSCLC patients' outcome. Our findings established the relevance of the combinatorial inactivation of p53 and PTEN in NSCLC progression and identified a subgroup of patients with a particularly aggressive disease.

Promoter hypermethylation of tumor suppressor and tumor-related genes in non-small cell lung cancers

Aberrant methylation of promoter CpG islands is known to be a major inactivation mechanism of tumor suppressor and tumor-related genes. To determine the clinicopathological significance of gene promoter methylation in non-small cell lung cancer (NSCLC), we examined the promoter methylation status of the APC, DAP-kinase, E-cadherin, GSTP1, hMLH1, p16, RASSF1A and RUNX3 genes in 75 NSCLCs and corresponding non-neoplastic lung tissues by methylation-specific PCR (MSP). The frequencies of methylation in NSCLCs and corresponding non-neoplastic lung tissues were: 37% (28 of 75) and 48% (36 of 75) for APC, 28% (21 of 75) and 13% (10 of 75) for DAP-kinase, 29% (22 of 75) and 15% (11 of 75) for E-cadherin, 1% (1 of 75) and 0% (0 of 75) for GSTP1, 7% (5 of 75) and 0% (0 of 75) for hMLH1, 31% (23 of 75) and 0% (0 of 75) for p16, 43% (32 of 75) and 4% (3 of 75) for RASSF1A, and 20% (15 of 75) and 3% (2 of 75) for RUNX3, respectively. Methylation of p16 was more frequent in squamous cell carcinomas than in adenocarcinomas (P < 0.05), and was associated with tobacco smoking (P < 0.05). On the contrary, methylation of APC and RUNX3 was more frequent in adenocarcinomas than in squamous cell carcinomas (P < 0.05). Thus, a different set of genes is thought to undergo promoter methylation, which leads to the development of different histologies. In addition, methylation of p16, RASSF1A and RUNX3 was mostly cancer-specific (P < 0.05), and may be utilized as a molecular diagnostic marker of NSCLCs.

Aberrant expression of pRb, p16, p14ARF, MDM2, p21 and p53 in stage I adenocarcinomas of the lung

Cancers are always associated with cell cycle abnormalities. To clarify the cell cycle abnormalities present in lung adenocarcinomas, various cell cycle regulatory proteins of both the pRb and p53 pathways were studied immunohistochemically in 50 cases of stage I adenocarcinoma of the lung. In regard to the pRb pathway, most adenocarcinomas showed frequent expression of both p16 and pRb proteins, and aberrant expression in the pRb pathway was observed in about one-quarter of stage I adenocarcinomas. In regard to the p53 pathway, the frequency of immunohistochemical positivity was 8% for p14ARF, 64% for MDM2, 20% for p53 and 24% for p21. In this pathway, the immunohistochemical profile of p14ARF-negative/MDM2-positive/p53-negative is characteristic of stage I adenocarcinoma of the lung. An inverse relationship was found between MDM2 and p53 protein and was associated with the differentiation status of stage I adenocarcinoma of the lung. Our results suggest that the disruption of the pRb and p53 pathways is frequently observed in the early stages of lung adenocarcinoma and might play an important role in the growth and differentiation of adenocarcinoma of the lung.

Role of p53 as a prognostic factor for survival in lung cancer: a systematic review of the literature with a meta-analysis

The role of p53, as a prognostic factor for survival in lung cancer, is controversial and the purpose of the present systematic review of the literature is to determine this effect. Published studies were identified with the objective to aggregate the available survival results after a methodological assessment using a scale specifically designed by the European Lung Cancer Working Party (ELCWP). To be eligible, a study had to deal with p53 assessment in lung cancer (primary site) only, and to provide a survival comparison according to the p53 status. Among the 74 eligible papers, 30 identified p53 abnormalities as a univariate statistically significant poor prognostic factor and 56 provided sufficient data to allow survival results aggregation. There was no significant difference between the trials that either showed or did not show a prognostic effect of p53 according to the methodological score or to the laboratory technique used. The studies were categorized by histology, disease stage, treatment and laboratory technique. Combined hazard ratios suggested that an abnormal p53 status had an unfavourable impact on survival: in any stage nonsmall cell lung cancer (NSCLC) the mean (95% confidence interval) was 1.44 (1.20-1.72) (number of studies included in the subgroup was 11), 1.50 (1.32-1.70) in stages I-II NSCLC (n=19), 1.68 (1.23-2.29) in stages I-IIIB NSCLC (n=5), 1.68 (1.30-2.18) in stages III-IV NSCLC (n=9), 1.48 (1.29-1.70) in surgically resected NSCLC (n=20), 1.37 (1.02-1.85) in squamous cell carcinoma (n=9), 2.24 (1.70-2.95) in adenocarcinoma (n=9), 1.57 (1.28-1.91) for a positive immunohistochemistry with antibody 1801 (n=8), 1.25 (1.09-1.43) for a positive immunohistochemistry with antibody DO-7 (n=16), and 1.65 (1.35-2.00) for an abnormal molecular biology test (n=13). Data were insufficient to determine the prognostic value of p53 in small cell lung cancer. In each subgroup of nonsmall cell lung cancer, p53 abnormal status was shown to be associated with a poorer survival prognosis.

Standardized perfusion value: universal CT contrast enhancement scale that correlates with FDG PET in lung nodules

The standardized enhancement value and standardized perfusion value allow comparison between different methods for quantification of contrast enhancement during computed tomography (CT). Standard perfusion values calculated from CT measurements of perfusion within pulmonary nodules compared favorably with those derived from previously reported enhancement data and correlated with standardized uptake values obtained from positron emission tomographic images (r = 0.8, P <.01).

Prognostic significance of p53 mutations in non-small cell lung cancer: a meta-analysis of 829 cases from eight published studies

Mutation of the p53 tumor suppressor gene is considered a possible marker of poor survival among patients with non-small cell lung cancer (NSCLC). This report presents the results of a meta-analysis of the available data addressing this issue. Using previously described methods, a protocol was developed for a meta-analysis examining the prognostic significance of p53 mutations in NSCLC. Two-year survival data derived from 829 patients in eight published studies were analyzed using a general variance-based method employing confidence intervals described by Greenland (Epidemiol. Rev. 9 (1986) 1-30). The outcome of interest was a summary relative risk (RRs) reflecting the risk of death at 2 years associated with p53 mutation positive versus p53 negative disease. Prior to calculation of a RRs, an analysis for homogeneity (Q) showed Q to equal 22.3. With 8 degrees of freedom, this yielded a P value corresponding to P<0.005. This indicated substantial heterogeneity across studies in terms of their estimate of effect. Although a RRs of 1.52 was found when all eight studies were combined (favoring a negative prognostic role for p53 mutation), the validity of this estimate is questionable since the existing heterogeneity indicates that factors other than p53 mutation account for the variability in RRs across studies. Sensitivity analyses suggested that selection bias might represent an important source of variability in that p53 mutations may differ in their effects on biological behavior of NSCL tumors. Other possible confounders include smoking history, race, geographic location of study and socio-economic status. The available data do not support a clear role for p53 mutation as a prognostic marker in NSCLC. It appears that multiple sources of bias may contribute to spurious association of p53 mutation status and survival. Future analyses must control for possible confounders in order to determine whether certain p53 mutations are truly associated with poor clinical outcome.

Association between smoking and tumor progression in Japanese women with adenocarcinoma of the lung

We studied the effect of smoking on tumor progression in 3312 patients with lung cancer registered at the National Matsudo Hospital and National Cancer Center Hospital East between 1977 and 1996. The odds ratios of the following variables for tumor extent (localized versus advanced disease) and hazard ratios for survival were calculated in both sexes separately using the logistic regression and Cox proportional hazard models, respectively: smoking history, number of cigarettes smoked per day, pack-years smoked, age, histological type, and the year of admission. Of the 943 women, 367 (38.9%) were smokers and 694 (73.6%) had adenocarcinoma, whereas of the 2369 men, 2255 (95.2%) were smokers and 1010 (42.6%) had adenocarcinoma. In female adenocarcinoma patients, the odds ratio (95% confidence interval) for advanced disease and the hazard ratio (95% confidence interval) for survival with an increase of 30 cigarettes smoked per day were 2.86 (1.49-5.49) and 1.52 (1.13-2.04), respectively, but in those with non-adenocarcinoma, the odds ratio and hazard ratio were 0.96 (0.41-2.23) and 1.13 (0.75-1.70), respectively. In male patients, smoking history influenced tumor progression regardless of histological type, but the odds ratios and hazard ratios were lower than those for women with adenocarcinoma. In conclusion, smoking habit was closely correlated with progression of adenocarcinoma in women. This association was not observed in women with non-adenocarcinoma and was weaker in men, suggesting various effects of smoking on lung cancer development depending on gender and the histological type of the tumor.