Molecular Evaluation of the Impact of Polymorphic Variants in Apoptotic (Bcl-2/Bax) and Proinflammatory Cytokine (TNF-α/IL-8) Genes on the Susceptibility and Progression of Myeloproliferative Neoplasms: A Case-Control Biomarker Study

The regulation of apoptosis (the programmed cell death) is dependent on the crucial involvement of BCL2 and BAX. The Bax-248G>A and Bcl-2-938 C>A polymorphic variations in the promoter sequences of the Bax and Bcl-2 gene have been recently associated with low Bax expression, progression to advanced stages, treatment resistance, and shortened overall survival rate in some hematological malignancies, including chronic myeloid leukemia (CML) and other myeloproliferative neoplasms. Chronic inflammation has been linked to various stages of carcinogenesis wherein pro-inflammatory cytokines play diverse roles in influencing cancer microenvironment leading to cell invasion and cancer progression. Cytokines such as TNF-α and IL-8 have been implicated in cancer growth in both solid and hematological malignancies with studies showing their elevated levels in patients. Genomic approaches have in recent years provided significant knowledge with the regard to the association of certain SNPs (single nucleotide polymerphisms) either in a gene or its promoter that can influence its expression, with the risk and susceptibility to human diseases including cancer. This study has investigated the consequences of promoter SNPs in apoptosis genes Bax-248G>A (rs4645878)/Bcl-2-938C>A (rs2279115) and pro-inflammatory cytokines TNF-α rs1800629 G>A/IL-8 rs4073 T>A on the risk and susceptibility towards hematological cancers. The study design has 235 individuals both male and female enrolled as subjects that had 113 cases of MPDs (myeloproliferative disorders) and 122 healthy individuals as controls. The genotyping studies were conducted through ARMS PCR (amplification-refractory mutation system PCR). The Bcl-2-938 C>A polymorphism showed up in 22% of patients in the study, while it was observed in only 10% of normal controls. This difference in genotype and allele frequency between the two groups was significant (p = 0.025). Similarly, the Bax-248G>A polymorphism was detected in 6.48% of the patients and 4.54% of the normal controls, with a significant difference in genotype and allele frequency between the groups (p = 0.048). The results suggest that the Bcl-2-938 C>A variant is linked to an elevated risk of MPDs in the codominant, dominant, and recessive inheritance models. Moreover, the study indicated allele A as risk allele which can significantly increase the risk of MPDs unlike the C allele. In case of Bax gene covariants, these were associated with an increased risk of MPDs in the codominant inheritance model and dominant inheritance model. It was found that the allele A significantly enhanced the risk of MPDs unlike the G allele. The frequencies of IL-8 rs4073 T>A in patients was found to be TT (16.39%), AT (36.88%) and AA (46.72%), compared to controls who were more likely to have frequencies of TT (39.34%), AT (37.70%) and AA (22.95%) as such, respectively. There was a notable overrepresentation of the AA genotype and GG homozygotes among patients compared to controls in TNF-α polymorphic variants, with 6.55% of patients having the AA genotype and 84% of patients being GG homozygotes, compared to 1.63% and 69%, respectively in controls. The data from the current study provide partial but important evidence that polymorphisms in apoptotic genes Bcl-2-938C>A and Bax-248G>A and pro-inflammatory cytokines IL-8 rs4073 T>A and TNF-α G>A may help predict the clinical outcomes of patients and determine the significance of such polymorphic variations in the risk of myeloproliferative diseases and their role as prognostic markers in disease management using a case-control study approach.

Antiapoptotic Gene Genotype and Allele Variations and the Risk of Lymphoma

BACKGROUND

The findings of earlier investigations of antiapoptotic gene genotypes and allele variants on lymphoma risk are ambiguous. This study aimed to examine the relationship between the mutation in the antiapoptotic genes and lymphoma risk among Saudi patients.

METHODS

This case-control study included 205 patients, 100 of whom had lymphoma (cases) and 105 who were healthy volunteers (controls). We used tetra amplification refractory mutation polymerase chain reaction (PCR) to identify antiapoptotic genes such as B-cell lymphoma-2 (BCL2-938 C > A), MCL1-rs9803935 T > G, and survivin (BIRC5-rs17882312 G > C and BIRC5-rs9904341 G > C). Allelic-specific PCR was used to identify alleles such as BIRC5-C, MCL1-G, and BIRC5-G.

RESULTS

The dominant inheritance model among cases showed that mutations in all four antiapoptotic genes were more likely to be associated with the risk of lymphoma by the odds of 2.0-, 1.98-, 3.90-, and 3.29-fold, respectively, compared to controls. Apart from the BCL-2-A allele, all three specified alleles were more likely to be associated with lymphoma by the odds of 2.04-, 1.65-, and 2.11-fold, respectively.

CONCLUSION

Unlike healthy individuals, lymphoma patients are more likely to have antiapoptotic gene genotypes and allele variants, apart from BCL-2-A alterations. In the future, these findings could be used to classify and identify patients at risk of lymphoma.

Genetic polymorphisms of Bcl-2 promoter in cancer susceptibility and prognosis: a meta-analysis

Bcl-2 is critical for tumorigenesis. However, previous studies on the association of Bcl-2 promoter polymorphisms with predisposition to different cancer types are somewhat contradictory. Therefore, we performed this meta-analysis regarding the relationship between Bcl-2 promoter single nucleotide polymorphisms (SNPs) and cancer susceptibility and prognosis. Up to August 2016, 32 original publications were identified covering two Bcl-2 promoter SNPs (rs2279115 and rs1801018). Our results showed statistically significant association between rs2279115 and cancer susceptibility and prognosis in all four genetic models but not in rs1801018. Subgroups analysis indicated that rs2279115 was associated with a significantly higher risk of cancer susceptibility in Asia but not in Caucasian. Furthermore, rs2279115 was associated with a significantly higher risk in digestive system cancer and endocrine system cancer but not in breast cancer, respiratory cancer and hematopoietic cancer. Simultaneously, rs2279115 was correlated with a significantly higher risk of cancer prognosis in Asia but not in Caucasian. Considering these promising results, rs2279115 may be a tumor marker for cancertherapy in Asia. Sensitivity analysis show four gene model were stable, and no publication bias was observed in all four gene model. Large sample size, different ethnic population and different cancer type are warranted to validate this association.

Polymorphism in apoptotic BAX (-248G>A) gene but not in anti-apoptotic BCL2 (-938C>A) gene and its protein and mRNA expression are associated with cervical intraepithelial neoplasia

HPV is associated with cervical cancer and plays a crucial role in tumor formation. Apoptosis is regulated by different pathways involving genes that either promote (BCL2 gene) or inhibit (BAX gene) cell death. Our goal was to determine whether the BCL2-938C>A (rs2279115) and BAX-248G>A (rs4645878) single nucleotide polymorphisms (SNPs) are associated with squamous intraepithelial neoplasia (SIL) risk, and whether their phenotypic expression was impaired in these lesions. Two hundred and thirty-one cases showing SIL were classified as low SIL (LSIL, n = 101) or high SIL (HSIL, n = 130), and control subjects (n = 266) with no gynecologically proven SIL were recruited. No statistical difference in the genotype and allelic frequency of the BCL-2-938C>A polymorphism was observed among the groups. BCL2-938C/A and A/A homozygotes carriers had higher distribution of BCL-2-expressing cells in stroma in the SIL group. BCL2 mRNA-expression was not correlated with BCL2-938C>A SNPs in both groups. We did find a strong association of the BAX GG genotype and risk for SIL. No difference was observed between LSIL and HSIL groups. In BAX-248G/A and A/A homozygote carriers, the number of BAX-expressing cells was lower the epithelium area in SIL. However, mRNA expression was higher in SIL patients than in the control group. In conclusion, our data provide evidence that allele G carriers in the BAX-248G>A promoter SNP may influence the development of SIL. However, this genotype does not influence the SIL outcome. Additionally, we suggest a possible role of HPV infection in the inhibition of the expression of BAX protein, decreasing cell death, and favoring cervical carcinogenesis.

Polymorphisms of BCL2 and BAX Genes Associate with Outcomes in Advanced Non-small cell lung cancer Patients treated with platinum-based Chemotherapy

Single-nucleotide polymorphisms (SNP) of the gene belonging to the BCL2 family are thought to play a role in chemotherapy resistance. This study investigated the association of BCL2-938C>A(rs2279115) and BAX-248G>A(rs4645878) promoter region SNPs and the clinical responses and outcomes of 235 non-small cell lung cancer (NSCLC) patients treated with platinum-based chemotherapy. The data suggested that BAX-248GA and GA+AA genotype was associated with poor response [odds ratio (OR) 1.943, p = 0.039; OR 1.867, p = 0.038, respectively] to chemotherapy, and BCL2-938CA, CA+AA and BAX-248GA, AA and GA+AA were associated with poor progression-free survival (PFS) [hazard ratio (HR) 1.514, p = 0.004; HR 1.456, p = 0.009; HR 1.449, p = 0.013; HR 2.006, p = 0.010; HR 1.506, p = 0.003, respectively] and BCL2-938CA, AA and CA+AA and BAX-248GA, AA and GA+AA were associated with poor overall survival (OS) (HR 2.006, p < 0.001; HR 2.322, p < 0.001; HR 2.096, p < 0.001; HR 1.632, p = 0.001; HR 2.014, p = 0.010; HR 1.506, p < 0.001, respectively). Furthermore, combination of these two polymorphisms showed patients with 2–4 variant alleles of these two genes associated with poor PFS and OS (HR 1.637, p = 0.001; HR 2.365, p < 0.001). The data from the current study provide evidence that BCL2-938C>A and BAX-248G>A polymorphisms may be useful in predicting clinical outcomes of patients with advanced inoperable NSCLC to platinum-based chemotherapy.

Role of Bcl-2 -938 C>A polymorphism in susceptibility and prognosis of cancer: a meta-analysis

The association between B-cell lymphoma 2 (Bcl-2) polymorphism and cancer is under debate and remains elusive. This meta-analysis was performed to evaluate the relationships of Bcl-2 -938 C>A polymorphism (rs2279115) with susceptibility and prognosis of cancer. Odds ratios (ORs) were used to measure the association between Bcl-2 polymorphisms and cancer risk. Hazard ratios (HRs) were used to measure the association between Bcl-2 polymorphisms and cancer prognosis. On the basis of 26 studies about Bcl-2 -938C>A polymorphism and cancer, we found Bcl-2 -938 C>A polymorphism was significantly associated with increased cancer risk in dominant model (OR = 1.12, 95%CI: 1.00-1.25, P = 0.04), recessive model (OR = 1.38, 95%CI: 1.11-1.71, P = 0.004), allelic model (OR = 1.15, 95%CI: 1.04-1.28, P = 0.007) and homozygote comparison(OR = 1.44, 95%CI: 1.11-1.87, P = 0.006). Furthermore, Bcl-2 -938 C>A polymorphism was significantly associated with increased cancer risk in Asians but not in Caucasians. Moreover, Bcl-2 -938 C>A polymorphism was not significantly associated with the prognosis of cancer (AA vs CA: OR = 0.99, 95%CI: 0.77-1.27, P = 0.93; AA vs CC: OR = 0.92, 95%CI: 0.65-1.30, P = 0.63; AC vs CC: OR = 0.94, 95%CI: 0.80-1.11, P = 0.48; CC vs AA+CA: OR = 1.21, 95%CI: 0.69-2.13, P = 0.50; AA vs CC+CA: OR = 0.99, 95%CI: 0.48-2.04, P = 0.97). Studies with larger samples and gene-environment interactions are needed to validate our findings.

A Polymorphism (rs1801018, Thr7Thr) of BCL2 is Associated with Papillary Thyroid Cancer in Korean Population

Objectives

Among the apoptosis signals, B-cell CLL/lymphoma 2 (BCL2) is a well-known regulator of apoptosis with anti-apoptotic properties. We investigated here whether single nucleotide polymorphisms (SNPs) of the BCL2 were associated with host susceptibility of papillary thyroid cancer (PTC) occurrence and clinicopathologic parameters.

Methods

Ninety-two PTC patients and 222 control subjects were recruited. One promoter SNP (rs2279115, -938A/C) and one synonymous SNP (rs1801018, Thr7Thr) in the BCL2 gene were selected and genotyped using direct sequencing. Multiple logistic regression models were performed to evaluate odds ratios, 95% confidence intervals, and P-values.

Results

rs1801018 of the BCL2 gene was not associated with the development of PTC. In the clinicopathologic features, rs1801018 SNP was associated with the number and location. The G allele frequency of rs1801018 in PTC patients with multifocality (13.3%) was about four-fold higher than that in PTC patients with unifocality (3.4%). The G allele frequency of rs1801018 in PTC patients with both lobes (15.4%) was increased by about five-fold, compared to PTC patients with one lobe (3.2%).

Conclusion

The results suggest that synonymous SNP rs1801018 and the G allele of the BCL2 gene may be associated with the multifocality and bilaterality of PTC in Korean population.

BCL-2 (-938C > A) polymorphism is associated with breast cancer susceptibility

Background

BCL-2 (B-cell leukemia/lymphoma 2) gene has been demonstrated to be associated with breast cancer development and a single nucleotide polymorphism (SNP; -938C > A) has been identified recently. To investigate whether this polymorphism functions as a modifier of breast cancer development, we analyzed the distribution of genotype frequency, as well as the association of genotype with clinicopathological characteristics. Furthermore, we also studied the effects of this SNP on Bcl-2 expression in vitro.

Methods

We genotyped the BCL-2 (-938C > A) in 114 patients and 107 controls, and analyzed the estrogen receptor (ER), progestogen receptor (PR), C-erbB2 and Ki67 status with immunohistochemistry (IHC). Different Bcl-2 protein levels in breast cancer cell lines were determined using western blot. Logistic regression model was applied in statistical analysis.

Results

We found that homozygous AA genotype was associated with an increased risk (AA vs AC+CC) by 2.37-fold for breast cancer development and significant association was observed between nodal status and different genotypes of BCL-2 (-938C > A) (p = 0.014). AA genotype was more likely to develop into lobular breast cancer (p = 0.036). The result of western blot analysis indicated that allele A was associated with the lower level of Bcl-2 expression in breast cancer cell lines.

Conclusions

AA genotype of BCL-2 (-938C > A) is associated with susceptibility of breast cancer, and this genotype is only associated with the nodal status and pathological diagnosis of breast cancer. The polymorphism has an effect on Bcl-2 expression but needs further investigation.