Functional genetic variants of CTLA-4 and risk of tobacco-related oral carcinoma in high-risk North Indian population

Impact of the cytotoxic T-lymphocyte associated antigen-4 rs231775 A/G polymorphism on cancer risk

Background

Cytotoxic T-lymphocyte associated antigen-4 (CTLA-4) is an immunosuppressive checkpoint that is involved in the development and metastasis of cancers. Several studies revealed that CTLA-4 rs231775A/G polymorphism may be associated with the risk of cancer in some populations, but the conclusions of these studies are not consistent.

Methods

We conducted a pooled analysis with eligible studies to explore the association between the CTLA-4 rs231775 variant and cancer risk. Additionally, we used in silico tools to evaluated the expression of CTLA-4 on urinary system cancer. Moreover, we adopted the enzyme-linked immunosorbent assay (ELISA), and Gene Set Enrichment Analysis (GSEA) to investigate the effects of CTLA-4 on bladder cancer (BLCA).

Results

In total, 92 case-control studies involving 29,987 patients with cancer and 36,484 healthy individuals (controls) were included in the pooled analysis. In the stratified analysis based on cancer type, the rs231775 A/G polymorphism was associated with increased bladder cancer risk in the heterozygote contrast model (OR = 1.23, 95% CI = 1.01-1.51, P = 0.040). The race-stratified analysis revealed that East Asians with the GG genotype had a 12% lower risk of developing cancer than those with the GA + AA genotype (95% CI = 0.81-0.95, P = 0.001). The in silico analysis showed that CTLA-4 expression was augmented in patients with BLCA. The ELISA results revealed that CTLA-4 expression was reduced in patients with BLCA carrying the AA genotype. Several signaling pathways, including cytokine-cytokine receptor interactions and T-cell receptor signaling, were associated with CTLA-4 expression.

Conclusion

The CTLA-4 rs231775 A/G polymorphism is associated with cancer risk in East Asian population. This polymorphism is especially associated with BLCA.

Evidence of Association between CTLA-4 Gene Polymorphisms and Colorectal Cancers in Saudi Patients

Cytotoxic T lymphocyte antigen-4 (CTLA-4) has been identified as an immunosuppressive molecule involved in the negative regulation of T cells. It is highly expressed in several types of autoimmune diseases and cancers including colorectal cancer (CRC). (1) Objective: To explore the association between CTLA-4 single nucleotide polymorphisms (SNP) and risk to (CRC) in the Saudi population. (2) Methods: In this case-control study, 100 patients with CRC and 100 matched healthy controls were genotyped for three CTLA-4 SNPs: rs11571317 (-658C > T), rs231775 (+49A > G) and rs3087243 (CT60 G > A), using TaqMan assay method. Associations were evaluated using odds ratios (ORs) and 95% confidence intervals (95% CIs) for five inheritance models (co-dominant, dominant, recessive, over-dominant and log-additive). Furthermore, CTLA-4 expression levels were evaluated using quantitative real-time PCR (Q-RT-PCR) in colon cancer and adjacent colon tissues. (3) Results: Our result showed a significant association of the G allele (OR = 2.337, p < 0.0001) and GG genotype of the missense SNP +49A > G with increased risk of developing CRC in codominant (OR = 8.93, p < 0.0001) and recessive (OR = 16.32, p < 0.0001) models. Inversely, the AG genotype was significantly associated with decreased risk to CRC in the codominant model (OR = 0.23, p < 0.0001). In addition, the CT60 G > A polymorphism exhibited a strong association with a high risk of developing CRC for the AA genotype in codominant (OR = 3.323, p = 0.0053) and in allele models (OR = 1.816, p = 0.005). No significant association was found between -658C > T and CRC. The haplotype analysis showed that the G-A-G haplotype of the rs11571317, rs231775 and rs3087243 was associated with high risk for CRC (OR = 57.66; p < 0.001). The CTLA-4 mRNA gene expression was found significantly higher in tumors compared to normal adjacent colon samples (p < 0.001). (4) Conclusions: Our findings support an association between the CTLA-4 rs231775 (+49A > G) and rs3087243 (CT60 G > A) polymorphisms and CRC risk in the Saudi population. Further validation in a larger cohort size is needed prior to utilizing these SNPs as a potential screening marker in the Saudi population.

A Novel Role for the Soluble Isoform of CTLA-4 in Normal, Dysplastic and Neoplastic Oral and Oropharyngeal Epithelia

Background: Head and neck cancer (HNC) has a high mortality rate, with late diagnosis remaining the most important factor affecting patient survival. Therefore, it is imperative to identify markers that aid in early detection and prediction of disease progression. HNCs evade the immune system by different mechanisms, including immune checkpoints. Cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) is an immune checkpoint receptor that downregulates anti-tumour immune responses, with evidence of involvement in HNC. The less studied, alternatively spliced, soluble isoform (sCTLA-4) also plays an immunosuppressive role that contributes to immune escape. We quantified sCTLA-4 in normal, potentially malignant, and malignant oral and oropharyngeal tissues to elucidate any role in tumourigenesis and identify its potential as a biomarker for diagnosis and patient stratification. Methods: Normal, low- and high-grade epithelial dysplasia, and squamous cell carcinoma oral and oropharyngeal biopsies were selectively stained for sCTLA-4 and quantified using the image analysis software QuPath. Results: Distinct sCTLA-4 staining patterns were observed, in which normal epithelial sCTLA-4 expression correlated with keratinocyte differentiation, while disrupted expression, both in intensity and localisation, was observed in dysplastic and neoplastic tissues. Conclusions: Our data indicate an additional, previously unknown role for sCTLA-4 in epithelial cell differentiation and proliferation. Furthermore, our findings suggest the potential of sCTLA-4 as a biomarker for predicting disease progression and patient stratification for targeted HNC therapies.

Cytotoxic T-lymphocyte antigen 4 polymorphisms and breast cancer susceptibility: Evidence from a meta-analysis

BACKGROUND

Cytotoxic T-lymphocyte antigen 4 (CTLA-4) is an immune checkpoint and regulates the immune function of T cells. However, previous findings regarding the association of CTLA-4 polymorphisms and breast cancer remain inconclusive. Therefore, we performed a meta-analysis to investigate the potential effects of five polymorphisms (-1722 T/C, -1661 A/G -318 C/T, +49 A/G, and CT60 A/G) in the CTLA-4 gene on breast cancer susceptibility.

METHODS

Relevant literatures were systematically searched through electronic databases including PubMed, EMBASE, and Web of Science up to October 10, 2021. Available data were extracted and odds ratios (ORs) with 95% confidence intervals were used to estimate the pooling effect size. The Newcastle-Ottawa Scale was applied for assessing the quality of included studies. We conducted subgroup analyses based on ethnicity and control sources to explore levels of heterogeneity. Moreover, sensitivity analysis and publication bias were assessed.

RESULTS

Finally, a total of 12 eligible studies regarding CTLA-4 polymorphisms and breast cancer were included. For overall analyses, only the +49 A/G polymorphism was significantly associated with breast cancer under allelic (OR = 1.19), dominant (OR = 1.27), and recessive (OR = 1.27) models. Ethnicity-based subgroup analysis found that the +49 A/G polymorphism has a significant risk (OR = 2.03) of breast cancer under the recessive model in the non-Asian population. Studies with hospital-based controls showed that the +49 A/G polymorphism has significant breast cancer risks under allelic (OR = 1.44), dominant (OR = 1.86), and recessive (OR = 1.60) models. In addition, those with population-based controls found that -1722 T/C polymorphism has a significant breast cancer risk under allelic (OR = 1.19) and dominant (OR = 1.26) models.

CONCLUSION

This meta-analysis suggested that CTLA-4 + 49 A/G polymorphism may significantly associate with breast cancer susceptibility. Future studies containing various populations are helpful for evaluating the impacts of CTLA-4 polymorphisms on breast cancer susceptibility.

Unraveling molecular mechanisms of Head and neck cancer

Malignancies that develop from mucosal epithelium of the upper aerodigestive tract are known as head and neck squamous cell carcinomas (HNSCC). Heterogeneity, late stage diagnosis and high recurrence rate are big hurdles in head and neck treatment regimen. Presently, the biomarkers available for diagnosis and prognosis of HNSCC are based on smoking as the major risk habit. This review shed light on the differential environment of HNSCC in smokeless tobacco consuming Indian patients. Frequent mutation in genes involved in DNA repair pathway (p53), cell proliferation (PIK3CA, HRAS) and cell death (CASP8, FADD) are common in western population. On the contrary, the genes involved in metastasis (MMPs, YAP1), lymphocyte proliferation (TNFRSF4, CD80), cell-cell adhesion (DCC, EDNRB), miRNA processing (DROSHA) and inflammatory responses (TLR9, IL-9) are mutated in Indian HNSCC patients. Gene ontology enrichment analysis highlighted that responses to chemical stimulus, immune pathways and stress pathways are highly enriched in Indian patients.

Comprehensive Analysis of 29,464 Cancer Cases and 35,858 Controls to Investigate the Effect of the Cytotoxic T-Lymphocyte Antigen 4 Gene rs231775 A/G Polymorphism on Cancer Risk

In our previous studies, we found that the rs231775 polymorphism of cytotoxic T-lymphocyte antigen 4 (CTLA-4) is associated with risks of different cancer types; however, the association remains controversial and ambiguous, so we conducted an in-depth meta-analysis to verify the association. A complete search of the PubMed, Google Scholar, Embase, Chinese databases, and Web of Science was conducted without regard to language limitations, covering all publications since November 20, 2021. The search criteria for cancer susceptibility associated with the polymorphism in the CTLA-4 gene rs231775 resulted in 87 case-control studies with 29,464 cases and 35,858 controls. The association strength was analyzed using odds ratios and 95% confidence intervals. Overall, we found that the CTLA-4 rs231775 polymorphism may reduce cancer risk. A stratified cancer type analysis showed that CTLA-4 rs231775 polymorphism was a risk factor for colorectal cancer and thyroid cancer; on the other hand, it was a protective factor for breast cancer, liver cancer, cervical cancer, bone cancer, head and neck, and pancreatic cancer. We also classified cancer into five systems and observed an increased association with digestive tract cancer, decreased associations with orthopedic tumors, tumors of the urinary system, and gynecological tumors. In the subgroup based on race, decreased relationships were observed in both Asians and Caucasians. The same decreased association was also shown in the analysis of the source of control analysis. Our present study indicates that the CTLA-4 rs231775 polymorphism contributes to cancer development and aggression.

Identification and Validation of a Hypoxia-Immune-Based Prognostic mRNA Signature for Oral Squamous Cell Carcinoma

BACKGROUND

Oral squamous cell carcinoma (OSCC) is a commonly encountered head and neck malignancy. Increasing evidence shows that there are abnormal immune response and chronic cell hypoxia in the development of OSCC. However, there is a lack of a reliable hypoxia-immune-based gene signature that may serve to accurately prognosticate OSCC.

METHODS

The mRNA expression data of OSCC patients were extracted from the TCGA and GEO databases. Hypoxia status was identified using the t-distributed Stochastic Neighbor Embedding (t-SNE) algorithm. Both ESTIMATE and single-sample gene-set enrichment analysis (ssGSEA) were used for further evaluation of immune status. The DEGs in different hypoxia and immune status were determined, and univariate Cox regression was used to identify significantly prognostic genes. A machine learning method, least absolute shrinkage and selection operator (LASSO) Cox regression analysis, allowed us to construct prognostic gene signature to predict the overall survival (OS) of OSCC patients.

RESULTS

A total of 773 DEGs were identified between hypoxia high and low groups. According to immune cell infiltration, patients were divided into immune high, medium, and low groups and immune-associated DEGs were identified. A total of 193 overlapped DEGs in both immune and hypoxia status were identified. With the univariate and LASSO Cox regression model, eight signature mRNAs (FAM122C, RNF157, RANBP17, SOWAHA, KIAA1211, RIPPLY2, INSL3, and DNAH1) were selected for further calculation of their respective risk scores. The risk score showed a significant association with age and perineural and lymphovascular invasion. In the GEO validation cohort, a better OS was observed in patients from the low-risk group in comparison with those in the high-risk group. High-risk patients also demonstrated different immune infiltration characteristics from the low-risk group and the low-risk group showed potentially better immunotherapy efficacy in contrast to high-risk ones.

CONCLUSION

The hypoxia-immune-based gene signature has prognostic potential in OSCC.

Correlative analysis between cytotoxic T lymphocyte antigen 4 genetic polymorphisms and head and neck cancer susceptibility: A protocol for systematic review and meta-analysis

BACKGROUND

Previous published studies have reported the association of cytotoxic T lymphocyte antigen 4 (CTLA-4) genetic polymorphisms with the susceptibility to head and neck cancer, but the results remain controversial. We therefore will conduct a meta-analysis to investigate the relationship between CTLA-4 genetic polymorphisms and head and neck cancer susceptibility.

METHODS

We will systematically search case-control studies for potential eligible studies from Cochrane Library, EMBASE, Google Scholar, PubMed, China Biomedical Database, WanFang database, and China National Knowledge Infrastructure (CNKI). Additionally, we will also examine other sources to avoid missing potential trials. Two authors will independently collect and perform the study selection, data extraction, and study methodological quality. Statistical analyses were utilized using STATA 12.0 and RevMan 5.3, and the odds ratios (ORs) with 95% confidence intervals (95% CI) were used to estimate the strength of the association of CTLA-4 genetic polymorphisms with the susceptibility to head and neck cancer.

RESULTS

This protocol study will assess the relationship between CTLA-4 genetic polymorphisms and head and neck cancer susceptibility.

CONCLUSION

The findings of this study will provide systematic evidence for future guidance developing and clinical decision making in patients with head and neck cancer.

ETHICS AND DISSEMINATION

Ethical approval will not be required as this study is a systematic review.

PROTOCOL REGISTRATION NUMBER

DOI 10.17605/OSF.IO/BFJTZ (https://osf.io/bfjtz/).

Immune Checkpoint Inhibitors in Oral Cavity Squamous Cell Carcinoma and Oral Potentially Malignant Disorders: A Systematic Review

Cancers of the oral cavity cause significant cancer-related death worldwide. While survival rates have improved in recent years, new methods of treatment are being investigated to limit disease progression and to improve outcomes, particularly in oral cavity squamous cell carcinoma (OSCC) and oral potentially malignant disorders (OPMD). The emerging treatment modality of immunotherapy targets immune checkpoint molecules including PD-1 and its ligand PD-L1, CTLA-4, LAG-3, and TIM-3 to enhance the host immune response against tumours, and to limit the growth and progression of cancer cells. In this systematic review, we searched five databases for keywords pertaining to oral cancers and OPMDs, along with immune checkpoint inhibitors, in order to summarize the current status of their use and efficacy in these diseases. A total of 644 different articles were identified between 2004 and 2019, with 76 deemed suitable for inclusion in the study, providing a total of 8826 samples. Combined results show expression of PD-1 and PD-L1 in the majority of OPMD and OSCC samples, with expression correlating with increased progression and decreased survival rates. Immunotherapy agents pembrolizumab and nivolumab target PD-1 and have been shown to prolong survival rates and improve disease outcomes, especially in combination with chemotherapy or radiotherapy. Despite the equivocal nature of current evidence, there is support for the prognostic and predictive value of immune checkpoint molecules, especially PD-L1, and many studies provide support for the effective use of immune checkpoint inhibitors in the management of OSCC. Limited data is available for OPMD, therefore this should be the focus of future research.

Association between the cytotoxic T-lymphocyte antigen 4-318C/T polymorphism and malignant tumor risk

The cytotoxic T-lymphocyte antigen 4 (CTLA-4) polymorphic loci -318 cytosine/thymine (-318C/T) has been previously implicated in malignant tumor susceptibility. However, there were no precise conclusions about the correlation, the results from published studies were inconclusive. The aim of the current meta-analysis was to investigate the associations between CTLA-4 -318C/T polymorphisms and risk of malignant tumors in Asian population. We conducted a search in PubMed, Embase, the Chinese Journals Full-Text Database, Chinese Biomedical Database, and the Wanfang database. All studies were published up to September 30, 2015. Two reviewers analysed the data independently. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the association. In total, 20 case-controlled studies with 3,539 cases and 4,690 controls were included in the final meta-analysis. The overall estimation demonstrated a significant association between CTLA-4 -318C/T polymorphism and malignant tumor risk in the Asian populations (TT+TC vs. CC: OR, 1.28; 95% CI, 1.07-1.53. TT vs. TC+CC: OR, 1.43; 95% CI, 1.03-1.99; TT vs. CC: OR, 1.51; 95% CI, 1.09-2.10. TC vs. CC: OR, 1.26; 95% CI, 1.06-1.50. T vs. C: OR, 1.25, 95% CI, 1.05-1.47). In the subgroup analysis by countries, we found that the dominant model (TT+TC vs. CC) revealed an increased risk of developing malignant tumors in the Chinese study population (OR, 1.41; 95% CI, 1.13-1.76), but no association was demonstrated in the other countries. The current meta-analysis suggests that CTLA-4 -318C/T polymorphism is significantly associated with the risk of malignance tumors in Asian populations, especially in those from China. Further studies for additional Asian countries are required to further evaluate the association.

CTLA4 polymorphisms and de novo malignancy risk after renal transplantation in Chinese recipients

Genetic polymorphisms in cytotoxic T lymphocyte-associated antigen 4 (CTLA4) play an influential role in graft rejection and the long-term clinical outcome of organ transplantation. We investigated the association of five CTLA4 single-nucleotide polymorphisms (SNPs) (rs733618 C/T, rs4553808 A/G, rs5742909 C/T, rs231775 A/G, and rs3087243 G/A) with de novo malignancy in 1463 Chinese renal transplantation (RT) recipients who underwent a 192-month follow-up. Multivariate analyses revealed that recipient rs231775 genotype is significantly associated with tumorigenesis (P = 0.012). Multiplicative interaction between rs231775 AA and possible risk factors of malignancy revealed two significant results: rs231775 AA × primary diseases and rs231775 AA × number of HLA-mismatch. The frequency of haplotype TACAG was significantly higher in the tumor group (17.07%) than that in the nontumor group (1.53%). In addition, aristolochic acid nephropathy (P = 0.003) and the time of discovery of tumor (P = 0.000) also were independently associated with tumorigenesis. Our data show that the CTLA4 genotype rs231775 AA may be one of risk factors for the development of malignancy and haplotype TACAG was susceptible haplotype in Chinese kidney transplant recipients.

RAGE gene polymorphism and environmental factor in the risk of oral cancer

Oral squamous cell carcinoma is a common neoplasm that is known to be causally associated with genetic factors and environmental carcinogens. The receptor for advanced glycosylation endproducts (RAGE) is a transmembrane protein of the immunoglobulin superfamily with broad specificity for multiple ligands, and it has been shown to play vital roles in several pathophysiologic processes, including diabetes, Alzheimer disease, renal disease, cardiovascular disease, and cancer. The present study aimed to assess the influences of RAGE gene polymorphisms, combined with environmental carcinogens on the predisposition to oral tumorigenesis. Five polymorphisms of the RAGE gene-including -374T>A (rs1800624), -429T>C (rs1800625), 1704G>T (rs184003), Gly82Ser (rs2070600), and a 63-bp deletion allele (-407 to -345)-were examined from 592 controls and 618 patients with oral cancer. We found that individuals carrying the polymorphic allele of rs1800625 are more susceptible to oral cancer (odds ratio [OR], 1.899; 95% confidence interval [CI], 1.355 to 2.661; adjusted OR [AOR], 2.053; 95% CI, 1.269 to 3.345) after adjustment for age, sex, betel nut chewing, and tobacco consumption. Moreover, we observed a significant association of rs1800625 variants with late-stage tumors (stage III/IV, OR, 1.736; 95% CI, 1.126 to 2.677; AOR, 1.771; 95% CI, 1.101 to 2.851) and large-size tumors (>2 cm in the greatest dimension; OR, 1.644; 95% CI, 1.083 to 2.493; AOR, 1.728; 95% CI, 1.089 to 2.741). Based on behavioral exposure of environmental carcinogens, the presence of 4 RAGE single-nucleotide polymorphisms (SNPs), combined with betel quid chewing and/or tobacco use, greatly augmented the risk of oral cancer. In addition, carriers of particular haplotypes of the 4 RAGE SNPs examined are more prone to develop oral cancer. These results indicate an involvement of RAGE SNP rs1800625 in the development of oral squamous cell carcinoma and implicate the interaction between RAGE gene polymorphisms and environmental mutagens as a predisposing factor of oral carcinogenesis.

Associations between the cytotoxic T lymphocyte antigen 4 polymorphisms and risk of bone sarcomas

Cytotoxic T lymphocyte antigen 4 (CTLA-4) genetic polymorphisms are implicated to be associated with susceptibility to bone sarcomas, but published studies have reported inconclusive results. The objective of our study was to conduct a meta-analysis investigating the associations between CTLA-4 gene polymorphisms and risk of bone sarcomas. PubMed and Embase databases were searched for all articles published up to June 2, 2013. Odds ratio (OR) with a 95 % confidence interval (95 % CI) was used to assess the association. Finally, 11 individual studies with a total of 2,951 cases with bone sarcomas and 3,396 controls were included in the meta-analysis. There were four studies on the CTLA-4 49G/A polymorphism, three studies on CTLA-4 318C/T polymorphism, two studies on CTLA-4 1661A/G polymorphism, and two studies on CTLA-4 60A/G polymorphism. Overall, CTLA-4 49G/A polymorphism was obviously associated with risk of bone sarcomas (A vs. G: OR = 1.36, 95 % CI = 1.20-1.54; AA vs. GG: OR = 2.24, 95 % CI = 1.67-2.99; AA vs.

AG/GG

OR = 2.00, 95 % CI = 1.53-2.62; AA/GA vs. GG: OR = 1.35, 95 % CI = 1.14-1.61). However, CTLA-4 318C/T, 1661A/G, and 60A/G polymorphisms were not associated with risk of bone sarcomas. The current meta-analysis suggests that CTLA-4 49G/A polymorphism is obviously associated with risk of bone sarcomas. More studies are needed to further evaluate the associations between CTLA-4 polymorphisms and risk of bone sarcomas.

Lack of association between cytotoxic T-lymphocyte antigen 4 (CTLA-4) -1722T/C (rs733618) polymorphism and cancer risk: from a case-control study to a meta-analysis

BACKGROUND

The association between cytotoxic T-lymphocyte antigen 4 (CTLA-4) gene -1722T/C polymorphism (rs733618) and cancer has been widely assessed, and a definitive conclusion remains elusive. We first performed a hospital based case-control study to measure this association of esophageal cancer with CTLA-4 -1722T/C polymorphism in Han Chinese population, and then carried out a meta-analysis to obtain a comprehensive evaluation for this issue.

METHODOLOGY/PRINCIPAL FINDINGS

This case-control study involved 629 esophageal squamous cell carcinoma (ESCC) cases and 686 age and gender well matched cancer-free controls. PCR-LDR (polymerase chain reaction-ligase detection reactions) method was used to identify genotypes. Meta-analysis was conducted by STATA (v12.0) software. This case-control study showed no significant difference in the genotype and allele distributions of CTLA-4 -1722T/C polymorphism between esophageal cancer cases and control subjects, in accord with the findings of the further meta-analysis in all genetic models. Evidence of large heterogeneity was observed among all eligible studies in the recessive model. Further subgroup analyses by ethnicity, cancer type and system, detected null associations in this meta-analysis.

CONCLUSION

This case-control study and the further meta-analysis, failed to identify the association between CTLA-4 -1722T/C polymorphism and cancer risk.

Association between CTLA-4 60G/A and -1661A/G polymorphisms and the risk of cancers: a meta-analysis

PURPOSE

CTLA-4 is one of the most fundamental immunosuppressive cotykines which belongs to the immunoglobulin super-family, and is expressed mainly on activated T cells. Previous studies have reported the existence of CTLA4 60G/A and CTLA4 -1661A/G polymorphism in cancers. However, the effects remain conflicting. Hence, we performed a meta-analysis to investigate the association between these polymorphisms and cancer risk.

METHODS

We searched the Pubmed and Web of Science databases until October 24, 2013 to obtain relevant published studies. Pooled odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for the relationship between CTLA4 gene polymorphisms and cancer susceptibility were calculated by stata 11 software. Heterogeneity tests, sensitivity analyses and publication bias assessments were also performed in our meta-analysis.

RESULTS

A total of 22 articles comprising 31 case-control studies concerning the CTLA-4 60G/A and CTLA-4 -1661A/G polymorphisms were included in the meta-analysis. The pooled results suggested the CTLA-4 60G/A polymorphism was significantly associated with an increased skin cancer risk (AA vs. GG: OR = 1.32, 95%CI = 1.09-1.59; AA vs. GA+GG: OR = 1.26, 95%CI = 1.07-1.48). For CTLA-4 -1661 A/G polymorphism, the results showed that the CTLA-4 -1661A/G polymorphism was significantly associated with an increased cancer risk (GA vs. AA: OR = 1.44, 95%CI = 1.13-1.82; GA+GG vs. AA: OR = 1.35, 95%CI = 1.07-1.69; G vs. A: OR = 1.21, 95%CI = 1.01-1.47), especially in gastric cancer, breast cancer, other cancers and in Asians population subgroups.

CONCLUSION

Our meta-analysis suggests that the CTLA-4 -1661A/G polymorphism is a potential factor for the susceptibility of cancer, especially in gastric cancer, breast cancer and other cancers, and the CTLA-4 60G/A polymorphism is significantly associated with increased skin cancer risk. The effect of the CTLA-4 -1661A/G polymorphism on cancer susceptibility especially exists in Asians and population based subjects.

Association between cytotoxic T lymphocyte antigen-4 +49A/G, -1722T/C, and -1661A/G polymorphisms and cancer risk: a meta-analysis

Cytotoxic T lymphocyte antigen-4 (CTLA-4), a key gene that contributes to the susceptibility and clinical course of cancer, is an important down-regulator of T cell activation and proliferation. The +49A/G polymorphism is commonly studied because of its association with cancer risks. However, other polymorphisms, such as -1722T/C and -1661A/G, have not been studied in detail. We performed a meta-analysis using 43 eligible case-control studies with a total of 19,089 patients and 21,388 controls to examine the association between CTLA-4 +49A/G, -1722T/C, and -1661A/G polymorphisms and cancer risk. We searched the PubMed and EMBASE databases for all articles published up to July 17, 2013. Individuals with the +49 A allele (AA/AG vs. GG, odds ratio (OR) = 1.21, 95% confidence interval (95% CI) = 1.16-1.27) and -1661 G allele (AG/GG vs. AA, OR = 1.52, 95% CI = 1.34-1.73) had increased cancer risk. However, no significant association between cancer risk and the -1722T/C polymorphism was found (CC/CT vs. TT, OR = 1.04, 95% CI = 0.92-1.16). In subgroup analysis for the +49A/G polymorphism, increased cancer risk remained in the subgroups of Asians (OR = 1.25, 95 % CI = 1.18-1.31), patients with breast cancer (OR = 1.28, 95% CI = 1.15-1.42), and patients with lung cancer (OR = 1.20, 95 % CI = 1.07-1.35). For the -1661A/G polymorphism, increased cancer risk remained in the subgroups of Asians (OR = 1.52, 95% CI = 1.34-1.73), patients with breast cancer (OR = 1.48, 95% CI = 1.07-2.03), and patients with oral cancer (OR = 3.16, 95% CI = 1.84-5.45). However, no significant increase in cancer risk was found in the subgroups for the -1722T/C polymorphism. In conclusion, the results suggest that +49A/G and -1661A/G polymorphisms in CTLA-4 are risk factors for cancers, whereas the -1722T/C polymorphism is not associated with an increased risk of cancer.

Association between the cytotoxic T-lymphocyte antigen 4 +49A/G polymorphism and bladder cancer risk

Cytotoxic T-lymphocyte antigen 4 (CTLA-4) is a potent immunoregulatory molecule that suppresses antitumor response by downregulating T cell activation. The most studied CTLA-4 +49A/G polymorphism has been associated with various cancers risks. However, little is known about the association between CTLA-4 +49A/G polymorphism and bladder cancer risk. A hospital-based case-control study was conducted in 300 patients with bladder cancer and 300 healthy controls matched with age and sex. The CTLA-4 +49A/G polymorphism was genotyped using polymerase chain reaction-restriction fragment length polymorphism. Patients with bladder cancer had a significantly lower frequency of CTLA-4 +49GG genotype [odds ratio (OR) = 0.44, 95 % confidence interval (CI) = 0.23, 0.85; P = 0.01] and G allele (OR = 0.73, 95 % CI = 0.56, 0.96; P = 0.02) than healthy controls. When stratifying by the stage, grade, and histological type of bladder cancer, we found no statistical association. This is the first study to highlight the significant association between CTLA-4 +49A/G polymorphism and bladder cancer risk. Additional studies are needed to confirm this finding.

Single nucleotide polymorphism in hMLH1 promoter and risk of tobacco-related oral carcinoma in high-risk Asian Indians

hMLH1 is a member of mismatch repair genes (MMR) that plays a crucial role in correcting replication errors, cell cycle arrest, apoptosis and oxidative stress. We explored the risk associated with hMLH1 -93 A>G (rs 1800734) single nucleotide polymorphism (SNP) with the oral squamous cell carcinoma (OSCC) in Asian Indians. We genotyped 242 patients with tobacco-related OSCC and 205 healthy controls by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. The frequency of AA genotype was found to be significantly (Pc<0.0006) lower in patients as compared to the controls (21.49% vs. 47.8%) while GG genotype showed significantly higher (Pc<0.0006) prevalence in patients as compared to the healthy controls (41.32% vs. 13.66%). In logistic regression analysis AG (adjusted OR=1.95, 95% CI=0.72-5.26) and GG genotype (adjusted OR=4.5, 95% CI=1.54-13.16, P=0.006) appeared susceptible when compared with the wild-type AA genotype. The allelic distribution showed that variant G allele is significantly higher (Pc<0.0004) in patients and associated with increased risk (adjusted OR=2.36, 95% CI=1.33-4.19, P=0.003) as compared to the wild-type A allele. Altogether, our results suggest that the hMLH1 -93 A>G polymorphism is associated with the higher risk of tobacco-related OSCC in Asian Indians and could be useful in screening population at a higher risk.