TP53 Codon 72 Polymorphisms and Lung Cancer Risk in the Bangladeshi Population

A review on the genetic polymorphisms and susceptibility of cancer patients in Bangladesh

Cancer is one of the major health burdens worldwide, and genetic polymorphisms in individuals are closely associated with cancer susceptibility. Like in many other developing countries, the risk of cancer is increasing among Bangladeshi population. Genetic polymorphisms in xenobiotic metabolic enzymes (CYP1A1, CYP2A6, CYP3A4, CYP3A5, NAT2, SULT1A), cell cycle regulatory proteins (TP53, HER2, MDM2, miR-218-2, TGFB), cell signaling protein (CDH1), DNA repair proteins (BRCA1, BRCA2, EXO1, RAD51, XRCC2, ECCR1, ERCC4, XPC, ERCC2), and others (HLA-DRB1, INSIG2, GCNT1P5) have been found to be associated with various cancers like cancers of breast, bladder, cervix, colon, lung, prostate, etc. in different studies with Bangladeshi population. In this review article, we have discussed these gene polymorphisms associated with cancers in the Bangladeshi population, and also made a comparison with other ethnic groups. This will probably be helpful in understanding drug effects, drug resistance, and personalized medicine in the population of this region.

The cell cycle regulatory gene polymorphisms TP53 (rs1042522) and MDM2 (rs2279744) in lung cancer: a meta-analysis

Lung cancer is one of the most common types of cancer in the world. Although the mechanism of lung cancer is still unknown, a large number of studies have found a link between gene polymorphisms and the risk of lung cancer. The tumor suppressor p53 plays a crucial role in maintaining genomic stability and tumor prevention. MDM2 is a critical regulator of the p53 protein. Despite the importance of p53 pathway in cancer, data on the contribution of SNPs of TP53 (rs1042522) and MDM2 (rs2279744) to the development of lung cancer are very contradictory. A metaanalysis that collects quantitative data from individual studies and combines their results has the advantage of improving accuracy, providing reliable estimates, and resolving those issues in which studies on individual associations are not effective enough. The aim of this study was to determine whether the TP53 (rs1042522) and MDM2 (rs2279744) polymorphisms confer susceptibility to lung cancer. A meta-analysis was conducted on the associations between the TP53 (rs1042522) and MDM2 (rs2279744) polymorphisms and lung cancer. A total of 51 comparison studies including 25,366 patients and 25,239 controls were considered in this meta-analysis. The meta-analysis showed no association between lung cancer and MDM2 (rs2279744) under any model. A noteworthy association of TP53 (rs1042522) with susceptibility to lung cancer in overall pooled subjects was observed under three different models (allele contrast, homozygote contrast (additive) and dominant). Stratification by ethnicity indicated an association between the TP53 (rs1042522) and lung cancer in Asians and Caucasians. This meta-analysis demonstrates that the TP53 (rs1042522), but not MDM2 (rs2279744) polymorphism may confer susceptibility to lung cancer.

TP53 Arg72Pro and XPD Lys751Gln Gene Polymorphisms and Risk of Lung Cancer in Bangladeshi Patients

Background:

Tumor suppressor gene (TP53) is considered as the most frequently mutated gene in almost all forms of human cancer. Moreover, genetic variations in the XPD gene affect the DNA repair capacity increasing cancer susceptibility. Polymorphisms within these genes can play a major role in determining individual lung cancer susceptibility. However, several studies have investigated this possibility; but reported conflicting results. Therefore, the objective of this study was to investigate the role of TP53 Arg72Pro and XPD Lys751Gln gene polymorphisms on lung cancer susceptibility in the Bangladeshi population.

Materials and Methods:

Study subjects comprised of 180 lung cancer patients and 200 healthy volunteers. Genetic polymorphism of TP53 was determined by multiplex PCR-based method, while XPD genotypes were analyzed using Polymerase Chain Reaction-based Restriction Fragment Length Polymorphism (PCR-RFLP) method. Lung cancer risk was estimated as odds ratio (OR) and 95% confidence interval (CI).

Results:

From the results, no significant association between TP53 Arg72Pro polymorphism and lung cancer risk was observed. Whereas, patients with homozygous mutant variants (Gln/Gln) of XPD at codon 751 were found significantly associated with lung cancer risk when compared to the control (OR=3.58; 95% CI=1.58-8.09; p=0.002). Lung cancer risk was found significantly higher with Gln/Gln variants of XPD among smokers (OR=4.03; 95% CI=1.11-14.63; p=0.026). Significant increased risk of lung cancer was found with Arg/Pro genotypes of TP53, Lys/Gln and Gln/Gln variants of XPD in individuals with family history of cancer (OR=3.44; 95% CI=1.36-8.72; p=0.011; OR=3.17; 95% CI=1.20-8.39; p=0.024; OR=16.35; 95% CI=0.92-289.5; p=0.007, respectively).

Conclusion:

The findings indicated that homozygous mutant variants (Gln/Gln) of XPD were associated with increased lung cancer risk, whereas TP53 Arg72Pro polymorphism was not associated with risk of lung cancer among Bangladeshi patients.

Association of TP53 Codon 72 Arg>Pro Polymorphism with Breast and Lung Cancer Risk in the South Asian Population: A Meta-Analysis

BACKGROUND

A transversion missense polymorphism of the TP53 tumor suppressor gene at the codon 72 codes proline instead of arginine causes an altered p53 protein expression and has been found to be associated with an elevated risk of various cancer; especially breast and lung cancer. As the previous case-control studies on the South Asian population have shown controversial results, we performed a meta-analysis to evaluate a precise estimation of the relationship between the TP53 Arg72Pro polymorphism with breast and lung cancer.

METHODS

A total of 12 related studies on the South Asian population have been included through comprehensive database searching. Six studies were selected for breast cancer meta-analysis involving 950 cases and 882 controls; the other six studies were for lung cancer meta-analysis including 975 cases and 1397 controls. The results have been determined by using the Review Manager (RevMan) 5.3. Additionally, the stability of our analysis was assessed by heterogeneity, publication bias analysis and sensitivity testing.

RESULTS

A significantly increased risk of breast cancer was found in Pro allele (Pro vs. Arg), co-dominant model 2 (Pro/Pro vs. Arg/Arg), dominant model (Pro/Pro + Arg/Pro vs. Arg/Arg). In case of lung cancer, significantly increased risk was found in the allele, co-dominant 1, co-dominant 2, co-dominant 3, dominant, and recessive models. No association with other genetic models with breast and lung cancer risk was found in the South Asian population.

CONCLUSIONS

Our results indicate that TP53 Arg72Pro polymorphism is a risk factor for the development of breast cancer and lung cancer in the South Asian population.

A cohort study on the association of MDM2 SNP309 with lung cancer risk in Bangladeshi population

BACKGROUND/AIMS

Bangladesh is a densely populated country with an increased incidence of lung cancer, mostly due to smoking. Therefore, elucidating the association of mouse double minute 2 homolog (MDM2) single nucleotide polymorphism (SNP) 309 (rs2279744) with lung cancer risk from smoking in Bangladeshi population has become necessary.

METHODS

DNA was extracted from blood samples of 126 lung cancer patient and 133 healthy controls. The MDM2 SNP309 was genotyped by polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP), using the restriction enzymes MspA1I. Logistic regression was then carried out to calculate odds ratios (ORs) and 95% confidence intervals (CIs) to estimate the risk of lung cancer. A meta-analysis of SNP309 was also carried out on 12,758 control subjects and 11,638 patient subjects.

RESULTS

In multivariate logistic regression, significantly increased risk of lung cancer was observed for MDM2 SNP309 in the dominant model (TG + GG vs. TT: OR, 2.13; 95% CI, 1.29 to 3.53). Stratification analysis revealed that age, sex, obesity, and smoking also increases the risk of lung cancer when carrying the MDM2 SNP309. Our meta-analysis revealed that MDM2 SNP309 was considerably associated with lung cancer in Asian populations (TG + GG vs. TT: OR, 1.32; 95% CI , 1.12 to 1.56; p = 0.019 for heterogeneity).

CONCLUSION

The MDM2 SNP309 was associated with high risk of lung cancer in Bangladeshi and Asian population, particularly with increased age, smoking, and body mass index.

The TP53 gene rs1042522 C>G polymorphism and neuroblastoma risk in Chinese children

TP53, a tumor suppressor gene, plays a critical role in cell cycle control, apoptosis, and DNA damage repair. Previous studies have indicated that the TP53 gene Arg72Pro (rs1042522 C>G) polymorphism is associated with susceptibility to various types of cancer. We evaluated the association of the TP53 gene rs1042522 C>G polymorphism with neuroblastoma susceptibility in a hospital-based study among the Chinese Han population. Enrolled were 256 patients and 531 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) generated using logistic regression models were used to determine the strength of the association of interest. No association was detected between rs1042522 C>G polymorphism and neuroblastoma risk. In our stratification analysis of age, gender, sites of origin, and clinical stages, we observed that subjects with rs1042522 CG/GG genotypes had a lower risk of developing neuroblastoma in the mediastinum (Adjusted OR=0.52, 95% CI=0.33-0.82, P=0.005) than those carrying the CC genotype. These results indicate that TP53 gene rs1042522 C>G polymorphism may exert a weak and site-specific effect on neuroblastoma risk in Southern Chinese children and warrant further confirmation.

Association between the TP53 and CYP2E1*5B gene polymorphisms and non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the most common form of lung cancer. Genetic polymorphisms in tumour suppressor genes and genes encoding xenobiotic metabolising enzymes alter the activity of their corresponding enzymes and are important individual susceptibility factors for NSCLC. Because of the lack of information in literature, the aim of our study was to investigate the role of the tumour suppressor gene TP53 (Arg72Pro) and the xenobiotic metabolising CYP2E1*5B gene polymorphisms on the risk of NSCLC development. The study population consisted of 172 patients and 172 controls (156 men and 16 women in each group). Genetic polymorphisms were determined with real-time polymerase chain reaction (PCR) and PCR restriction fragment length polymorphism (PCR-RFLP). Multivariate analysis showed a significant association with NSCLC for the combination between the TP53 codon72 Arg/Pro and the Pro/Pro genotypes (OR 2.21, 95 % CI 1.390-3.51; p=0.001). We also analysed whether combinations of these gene variants with GSTM1, GSTT1, GSTP1 exon 5 (Ile105Val), and GSTP1 exon 6 (Ala114Val) gene polymorphisms were associated with the NSCLC risk. A significant increase in the risk was observed for the following combinations: TP53 codon72 variant with GSTM1 null (OR 2.22, 95 % CI 1.23-4.04; p=0.009), GSTT1 null (OR 2.98, 95 % CI 1.49-5.94; p=0.002), and GSTP1 (Ala114Val) variant genotypes (OR 3.38, 95 % CI 1.54-7.41; p=0.002). Further studies with larger samples are needed to verify these findings.