Variable levels of bcl-2, bcl-x and bax mRNA in bladder cancer progression

Does the Presence of Heavy Metals Influence the Gene Expression and Oxidative Stress in Bladder Cancer?

Heavy metal toxicity is associated with cancer progression. Studies have reported the relation between some metal ions and bladder cancer (BC). Direct influence of such agents in bladder carcinogenesis is still needed. Total 49 BC patients were included in the study. Level of Pb, Cr, Hg and Cd, oxidative stress markers, and gene expression of Bcl-2, Bax, IL-6, AKT, and P38 genes were detected in cancer and non-cancerous tissues obtained from bladder cancer patients. Concentrations of Pb, Cr, and Cd were significantly elevated in cancer tissues than normal, while Hg level was significantly increased in normal tissue than cancer. MDA level was significantly higher and SOD activity was lower in the cancer tissues compared to non-cancerous. The expressions of Bcl-2, IL-6, AKT, and P38 were significantly increased in the cancer tissues than in normal tissues while Bax level was significantly increased in non-cancerous tissue than in cancer tissue. In cancer tissue, there were significant correlations between Cr level with expression of Bax, AKT, and P38 while Cd level was significantly correlate with Bax, IL-6, AKT, and P38expression. The correlation between Cr and Cd with the expression of Bax, IL-6, AKT, and P38 may indicate a carcinogenic role of these metals on progression of bladder cancer.

Lack of association between Bax promoter (-248G>A) single nucleotide polymorphism and susceptibility towards cancer: evidence from a meta-analysis

BACKGROUND

The Bcl-2-associated X protein (Bax) is a proapoptotic member of the Bcl-2 family known to be activated and upregulated during apoptosis. Single nucleotide polymorphisms (SNPs) in Bax promoter may participate in the process of carcinogenesis by altering its own expression and the cancer related genes. Bax-248G>A polymorphism has been implicated to alter the risk of cancer, but the listed results are inconsistent and inconclusive. In the present study, we performed a meta-analysis to systematically summarize the possible association of this polymorphism with the risk of cancer.

METHODOLOGY

We conducted a search of case-control studies on the associations of Bax-248G>A polymorphism with susceptibility to cancer in Pub Med, Science Direct, Wiley Online Library and hand search. Data from all eligible studies based on some key search terms, inclusion and exclusion criteria were extracted for this meta-analysis. Hardy-Weinberg equilibrium (HWE) in controls, power calculation, heterogeneity analysis, Begg's funnel plot, Egger's linear regression test, forest plot and sensitivity analysis were performed in the present study.

RESULTS

Cancer risk associated with Bax-248G>A polymorphism was estimated by pooled odds ratios (ORs) and 95% confidence intervals (95% CIs). The pooled ORs were calculated in allele contrast, homozygous comparison, heterozygous comparison, dominant and recessive model. Statistical significance was checked through Z and p-value in forest plot. A total of seven independent studies including 1772 cases and 1708 controls were included in our meta-analysis. Our results showed that neither allele frequency nor genotype distributions of this polymorphism were associated with risk for cancer in any of the genetic model. Furthermore, Egger's test did not show any substantial evidence of publication bias.

CONCLUSIONS/SIGNIFICANCE

This meta-analysis suggests that the Bax-248G>A polymorphism is not an important cancer risk factor. Nevertheless, additional well-designed studies with larger sample size focusing on different ethnicities and cancer types are required to further validate the results.

Bladder cancer SNP panel predicts susceptibility and survival

Bladder cancer is the fourth most common malignancy in men and the eighth most common in women in western countries. Single nucleotide polymorphisms (SNPs) in genes that regulate telomere maintenance, mitosis, inflammation, and apoptosis have not been assessed extensively for this disease. Using a population-based study with 832 bladder cancer cases and 1,191 controls, we assessed genetic variation in relation to cancer susceptibility or survival. Findings included an increased risk associated with variants in the methyl-metabolism gene, MTHFD2 (OR 1.7 95% CI 1.3-2.3), the telomerase TEP1 (OR 1.8 95% CI 1.2-2.6) and decreased risk associated with the inflammatory response gene variant IL8RB (OR 0.6 95% CI 0.5-0.9) compared to wild-type. Shorter survival was associated with apoptotic gene variants, including CASP9 (HR 1.8 95% CI 1.1-3.0). Variants in the detoxification gene EPHX1 experienced longer survival (HR 0.4 (95% CI 0.2-0.8). These genes can now be assessed in multiple study populations to identify and validate SNPs appropriate for clinical use.

Modification of alternative splicing of Bcl-x pre-mRNA in bladder cancer cells

To modify the splicing pattern of Bcl-x and compare the effect of this approach with that of the antisense gene therapy in BIU-87 cell line of bladder cancer, by using 5'-Bcl-x AS to target downstream alternative 5'-Bcl-x splice site to shift splicing from Bcl-xL to Bcl-xS and 3'-Bcl-x AS antisense to the 3'-splice site of exon III in Bcl-x pre-mRNA to down regulation of Bcl-xL expression, the inhibitory effects on cancer cells by modification of alternative splicing and antisense gene therapy were observed and compared by microscopy, MTT Assay, RT-PCR, FACS, Western bloting and clone formation. The growth of cells BIU-87 was inhibited in a dose- and time-dependent manner. Its inhibitory effect began 12 h after the exposure, reaching a maximum value after 72h. The number of cells decreased in S phase and the number increased in G1 phase. The ability to form foci was reduced and the antisense gene therapy was approximately half as efficient as modification of alternative splicing in inducing apoptosis. It is concluded that modification of splicing pattern of Bcl-x pre-mRNA in bladder cancer cell BIU-87 is better than antisense gene therapy in terms of tumor inhibition.

αCP-4, Encoded by a Putative Tumor Suppressor Gene at 3p21, But Not Its Alternative Splice Variant αCP-4a, Is Underexpressed in Lung Cancer

alpha CP-4 is an RNA-binding protein coded by PCBP4, a gene mapped to 3p21, a common deleted region in lung cancer. In this study we characterized the expression of alpha CP-4 and alpha CP-4a, an alternatively spliced variant of alpha CP-4, in lung cancer cell lines and non-small cell lung cancer (NSCLC) samples from early stage lung cancer patients. In NSCLC biopsies, an immunocytochemical analysis showed cytoplasmic expression of alpha CP-4 and alpha CP-4a in normal lung bronchiolar epithelium. In contrast, alpha CP-4 immunoreactivity was not found in 47% adenocarcinomas and 83% squamous cell carcinomas, whereas all of the tumors expressed alpha CP-4a. Besides, lack of alpha CP-4 expression was associated with high proliferation of the tumor (determined by Ki67 expression). By fluorescence in situ hybridization, >30% of NSCLC cell lines and tumors showed allelic losses at PCBP4, correlating with the absence of the protein. On the other hand, no mutations in the coding region of the gene were found in any of the 24 cell lines analyzed. By Northern blotting and real-time reverse transcription-PCR, we detected the expression of alpha CP-4 and alpha CP-4a messages in NSCLC and small cell lung cancer cell lines. Our data demonstrate an abnormal expression of alpha CP-4 in lung cancer, possibly associated with an altered processing of the alpha CP-4 mRNA leading to a predominant expression of alpha CP-4a. This may be considered as an example of alternative splicing involved in tumor suppressor gene inactivation. Finally, induction of alpha CP-4 expression reduced cell growth, in agreement with its proposed role as a tumor suppressor, and suggesting an association of this RNA-binding protein with lung carcinogenesis.