Tobacco carcinogen-metabolizing genes CYP1A1, GSTM1, and GSTT1 polymorphisms and their interaction with tobacco exposure influence the risk of head and neck cancer in Northeast Indian population

GSTM1 and GSTT1 deletions in penile cancer are associated with TNM stage but not with HPV DNA status

Deletions of the GSTT1 and GSTM1 are associated with chemical carcinogenesis and genitourinary malignancies like bladder cancer, where they correlate with increased tumor aggressiveness. In uterine cervical lesions, GSTT1 and GSTM1 deletions have also been suggested to facilitate the persistence of human papillomavirus (HPV) infection and HPV-induced carcinogenesis. This work addresses the hypothesis that GSTT1/GSTM1 deletions are associated with presence of HPV DNA and aggressiveness in penile cancer, a rare malignancy with HPV+ and HPV- subtypes. Tumor DNA samples and medical records from HPV+ and HPV- penile cancer patients were analyzed. Each sample was screened for GSTT1 and GSTM1 deletions and for the presence of HPV DNA using PCR-based techniques. 74.5 % of samples contained HPV DNA. 61.8 % of cases showed T2 and T3 staging. There were no differences in the frequencies of GSTT1/GSTM1 genotypes between HPV+ and HPV- cases (p>0.05). GSTT1wt/GSTMnull patients were more likely to have higher TNM stages compared with other genotypes (p=0.012), but no differences were observed concerning perineural invasion nor lymphovascular invasion. These findings indicate that GSTT1 and GSTM1 deletions are common in HPV+ and HPV- penile cancers. GSTM1 deletions in the presence of wild-type GSTT1 seems to be associated with tumor progression, and additional studies are warranted to confirm its potential as a prognostic marker in penile cancer.

Glutathione S-transferase theta 1 (GSTT1) deletion polymorphism and susceptibility to head and neck carcinoma: a systematic review with five analyses

Glutathione S-transferase theta 1 (GSTT1) enzyme plays a key role in the neutralization of electrophilic compounds such as carcinogens. Herein, we aimed to evaluate GSTT1 deletion polymorphism and susceptibility to head and neck carcinoma (HNC) according to 107 articles in a systematic review with five analyses. The databases of PubMed/Medline, Web of Science, Scopus, and Cochrane Library from the beginning of each database until June 21, 2023, with no restrictions to identify pertinent articles. The RevMan 5.3 software was used to calculate the effect sizes, which were displayed as the odds ratio (OR) along with a 95% confidence interval (CI). Both the publication bias and sensitivity analyses were performed using the CMA 3.0 software. A trial sequential analysis (TSA) was conducted. Of the 1966 records retrieved from four databases, 107 articles were included in the analysis. The combined analysis revealed that the pooled OR was 1.28 (95% CI: 1.14 to 1.44; p-value < 0.0001). The pooled OR was highest in mixed ethnicity. Nasopharyngeal cancer had the highest OR (1.84), followed by oral cancer (OR = 1.20), and laryngeal cancer (OR = 1.17). Studies with less than 200 samples had a higher OR compared to those with 200 or more samples. The studies with a quality score of 7 or more had a higher OR compared to those with a score of less than 7. When both age and sex are considered, while the OR of 1.42 is significant, the high heterogeneity suggests caution in interpreting these results. There is no evidence of publication bias. TSA reported that the study does not have sufficient statistical power. This comprehensive meta-analysis revealed a significant association between the GSTT1 null genotype and an increased risk of HNC, with variations based on factors such as ethnicity, cancer type, sample size, control source, and quality score.

Health effects associated with chewing tobacco: a Burden of Proof study

Chewing tobacco use poses serious health risks; yet it has not received as much attention as other tobacco-related products. This study synthesizes existing evidence regarding the health impacts of chewing tobacco while accounting for various sources of uncertainty. We conducted a systematic review and meta-analysis of chewing tobacco and seven health outcomes, drawing on 103 studies published from 1970 to 2023. We use a Burden of Proof meta-analysis to generate conservative risk estimates and find weak-to-moderate evidence that tobacco chewers have an increased risk of stroke, lip and oral cavity cancer, esophageal cancer, nasopharynx cancer, other pharynx cancer, and laryngeal cancer. We additionally find insufficient evidence of an association between chewing tobacco and ischemic heart disease. Our findings highlight a need for policy makers, researchers, and communities at risk to devote greater attention to chewing tobacco by both advancing tobacco control efforts and investing in strengthening the existing evidence base.

Gene-gene and gene-environment interaction: an important predictor of oral cancer among smokeless tobacco users in Karachi

Objective: To determine the risk for oral cancer caused by simultaneous occurrence of more than one of the tested cytochrome P450 1A1MspI, glutathione S-transferaseM1 null gnd Glutathione S-transferasesT1 null gene polymorphisms. Method: The cross-sectional case-control study was conducted from December 2011 to October 2016 at the Ziauddin University, Karachi, in collaboration with Dow University of Health Sciences, Karachi, and comprised oral squamous cell carcinoma cases in group A and healthy tobacco habit-matched controls in group B. All investigations were done using standardised laboratory protocols. The outcomes were determined in terms of association of various combinations of cytochrome P450 1A1MspI, glutathione S-transferasesM1 null and glutathione S-transferases T1 null polymorphisms with oral cancer. Data was analysed using SPSS 20. Results: Of the 238 subjects, 140(58.8%) were in group A and 98(41.2%) were in group B. Mean ages in group A and B were 47.1±12.22 and 41.6±14.58 years, respectively. Male/Female ratio in group A was 1.88:1 while 83.4% were using tobacco. When cytochrome P450 1A1MspI homozygous (m2/m2) and glutathione S-transferasesM1 null variants occured simultaneously in an individual, an odds ratio of 12.8 (95% confidence interval: 1.20-135.5; p=0.03) among overall tobacco chewers was observed. For glutathione S-transferasesM1 not null and glutathione S-transferasesT1 null variant combination among overall tobacco users, the conferred odds ratio was 4.58 (95% confidence interval: 0.99-21.2; p=0.05). The other studied gene combinations did not reveal significant associations (p>0.05). ---Continue

Association between the CYP1A1 MspI polymorphism and risk of head and neck cancer: a meta-analysis

The studies recommended the relationship between lots of polymorphisms with the head and neck cancers (HNCs) risk. Herein, we reported the association between the CYP1A1 MspI polymorphism and the risk of HNC in an updated meta-analysis. The PubMed/MEDLINE, Web of Science, Cochrane Library, and Scopus databases were searched until March 31, 2021, without any restrictions. Odds ratios (ORs) and 95% confidence intervals (CIs) were applied to assess a relationship between CYP1A1 MspI polymorphism and the HNC risk based on five applied genetic models by RevMan 5.3 software. Other analyses (sensitivity analysis, meta-regression, and bias analysis) were performed by CMA 2.0 software. Trial sequential analysis (TSA) was done by TSA software (version 0.9.5.10 beta). Among the databases and other sources, 501 recorded were identified that at last, 29 studies were obtained for the analysis. The pooled ORs were 1.28 (95%CI 1.09, 1.51; P = 0.003), 1.68 (95%CI 1.16, 2.45; P = 0.007), 1.24 (95%CI 1.03, 1.50; P = 0.02), 1.26 (95%CI 1.07, 1.48; P = 0.005), and 1.66 (95%CI 1.27, 2.16; P = 0.0002) for allelic, homozygous, heterozygous, recessive, and dominant models, respectively. Therefore, the m2 allele and m1/m2 and m2/m2 genotypes had significantly increased risks in HNC patients. With regards to stable results and enough samples, the findings of the present meta-analysis recommended that there was an association between CYP1A1 MspI polymorphism and the HNC risk.

Glutathione S-transferase Polymorphisms in Head and Neck Squamous Cell Carcinoma Treated with Chemotherapy and/or Radiotherapy

BACKGROUND/AIM

The Glutathione S-transferases (GSTs) are important carcinogen-metabolizing enzymes. Polymorphisms involved in these enzymes can modulate the development and treatment of head and neck cancer. To investigate the association of GSTs polymorphisms with head and neck cancer and risk factors, clinical-pathological features, and survival time of the patients treated with chemotherapy and/or radiotherapy.

METHODS

The GST gene polymorphisms were evaluated in 197 cases and 514 controls by PCR-RFLP-Polymerase Chain Reaction Restriction Fragment Length Polymorphism.

RESULTS

The GSTP-313 was associated with a decreased risk for HNSCC (p=0.050). The GSTP1 haplotype analysis revealed a higher frequency of the AC and AT haplotypes in the case group than in the control group (p=0.013 and p=0.019, respectively), and the opposite for G-C haplotype (p = 0.015). Yet, the different combinations between the genotypes were associated with an increased risk of cancer. The study showed no association between the polymorphisms and primary tumor site, clinical-pathological characteristics, treatment (chemotherapy and/or radiotherapy) and survival time of the patients.

CONCLUSION

The GST polymorphisms combination showed an increased risk for carcinogenesis, and studies with larger casuistry can contribute to the clarification of the role in individual patient differences for the response to chemotherapy and/or radiotherapy and identify biomarkers of susceptibility.

Association between polymorphisms in the CYP1A1, CYP2E1 and GSTM1 genes, and smoking, alcohol and upper digestive tract carcinomas in a high-incidence area of northern China

Metabolic gene variants, smoking, and alcohol consumption are important upper digestive tract cancer (UDTC) risk factors. However, the gene-gene and gene-environment interactions remain unclear. A case-control study in a high incidence area for upper digestive tract cancer was conducted in China. DNA was extracted from buffy coat samples for PCR or PCR-restriction fragment length polymorphism. Smoking and alcohol drinking status was determined by questionnaires. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the associations. After adjusting for confounding factors, smoking increased esophageal cancer (EC), gastric cardia cancer (GCC) and gastric antral carcinoma (GAC) risk by 3.594, 4.658, and 3.999-fold, respectively. Alcohol consumption increased EC, GCC and GAC risk by 1.953, 2.442 and 1.765-fold, respectively. The cytochrome P4501A1 (CYP1A1) rs4646903 T>C polymorphism increased GCC risk, the cytochrome P4502E1 (CYP2E1) rs2031920 C>T polymorphism increased EC risk, while the GSTM1 null genotype decreased EC risk. An association existed between the following: CYP1A1 rs4646903 and smoking in EC, GCC and GAC; CYP1A1 rs4646903 and alcohol consumption in EC and GCC; CYP2E1 rs2031920 and smoking in EC, GCC and GAC and CYP2E1 rs2031920 and alcohol consumption in EC and GCC. No association was observed between CYP1A1 and CYP2E1. The glutathione S-transferase mu 1 (GSTM1) null genotype decreased EC risk (OR=0.510). Smoking/drinking are upper digestive tract cancer risk factors. The CYP1A1 rs4646903 and CYP2E1 rs2031920 polymorphisms were risk factors of GCC or EC, and the GSTM1 null genotype may serve a protective role against EC. The results of the present study indicated that gene-environment interactions increase the risk of UDTC.

Survivin Promoter Polymorphism (-31 C/G): A Genetic Risk Factor for Oral Cancer

Background: The polymorphism of survivin gene at its promoter region is one of the risk factors for OSCC . This polymorphism involves substitution of G for C (9904341), and it is present at the cell cycle dependent elements and cell cycle homology region repressor binding motif of promoter. This study aimed to find the association between survivin -31C/G polymorphism and prevalence of OSCC in a subset of Pakistani population. Methodology: This case-control study was conducted on 47 cases with and 101 healthy individuals with no family history of cancer. We used polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) protocols. Results: The most common site of oral cancer in our research was the buccal mucosa followed by tongue and the least one was the labial mucosa. The histological tumor type of all 47 cases was squamous cell type. In our research, stage II had the highest prevalence, accounting for 34% of patients, while the prevalence of stage I was 31% in the case group. The prevalence of stage III and IV was 25% and 8%, respectively. The numbers of moderately and poorly differentiated tumors were equal. We found a significant association between the CC genotype of survivin and OSCC prevalence (OR was 9.395 at 95% CI: 1.0202-86.5251, p-value= 0.04). The GG genotype also showed significant P value (OR: 0.4709 with 95% CI: 0.2323- 0.9546 at a P VALUE of 0.0367). while no significant P value was noted for CG genotype (OR: 1.4317 with 95% CI: 0.7513 -2.8658, p- value= 0.31). Conclusion: Survivin -31G/C polymorphism was strongly associated with OSCC prevalence. The C allele was more common in case group as compared to healthy individuals living in Pakistan.

Association of DFNA5, SYK, and NELL1 variants along with HPV infection in oral cancer among the prolonged tobacco-chewers

Southeast Asia, especially India, is well known for the highest use of smokeless tobacco. These products are known to induce oral squamous cell carcinoma. However, not all long-term tobacco-chewers develop oral squamous cell carcinoma. In addition, germline variants play a crucial role in susceptibility, prognosis, development, and progression of the disease. These prompted us to study the genetic susceptibility to oral squamous cell carcinoma among the long-term tobacco-chewers. Here, we presented a retrospective study on prolonged tobacco-chewers of Northeast India to identify the potential protective or risk-associated germline variants in tobacco-related oral squamous cell carcinoma along with HPV infection. Targeted re-sequencing (n = 60) of 170 genetic regions from 75 genes was carried out in Ion-PGM™ and validation (n = 116) of the observed variants was done using Sequenom iPLEX MassARRAY™ platform followed by polymerase chain reaction-based HPV genotyping and p16-immunohistochemistry study. Subsequently, estimation of population structure, different statistical and in silico approaches were undertaken. We identified one nonsense-mediated mRNA decay transcript variant in the DFNA5 region (rs2237306), associated with Benzo(a)pyrene, as a protective factor (odds ratio = 0.33; p = 0.009) and four harmful (odds ratio > 2.5; p < 0.05) intronic variants, rs182361, rs290974, and rs169724 in SYK and rs1670661 in NELL1 region, involved in genetic susceptibility to tobacco- and HPV-mediated oral oncogenesis. Among the oral squamous cell carcinoma patients, 12.6% (11/87) were HPV positive, out of which 45.5% (5/11) were HPV16-infected, 27.3% (3/11) were HPV18-infected, and 27.3% (3/11) had an infection of both subtypes. Multifactor dimensionality reduction analysis showed that the interactions among HPV and NELL1 variant rs1670661 with age and gender augmented the risk of both non-tobacco- and tobacco-related oral squamous cell carcinoma, respectively. These suggest that HPV infection may be one of the important risk factors for oral squamous cell carcinoma in this population. Finally, we newly report a DFNA5 variant probably conferring protection via nonsense-mediated mRNA decay pathway against tobacco-related oral squamous cell carcinoma. Thus, the analytical approach used here can be useful in predicting the population-specific significant variants associated with oral squamous cell carcinoma in any heterogeneous population.

Assessment of DNA repair susceptibility genes identified by whole exome sequencing in head and neck cancer

Head and neck cancer (HNC), the sixth most common cancer globally, stands second in India. In Northeast (NE) India, it is the sixth most common cause of death in males and seventh in females. Prolonged tobacco and alcohol consumption constitute the major etiological factors for HNC development, which induce DNA damage. Therefore, DNA repair pathway is a crucial system in maintaining genomic integrity and preventing carcinogenesis. The present work was aimed to predict the consequence of significant germline variants of the DNA repair genes in disease predisposition. Whole exome sequencing was performed in Ion Proton™ platform on 15 case-control samples from the HNC-prevalent states of Manipur, Mizoram, and Nagaland. Variant annotation was done in Ion Reporter™ as well as wANNOVAR. Subsequent statistical and bioinformatics analysis identified significant exonic and intronic variants associated with HNC. Amongst our observed variants, 78.6% occurred in ExAC, 94% reported in dbSNP and 5.8% & 9.3% variants were present in ClinVar and HGMD, respectively. The total variants were dispersed among 199 genes with DSBR and FA pathway being the most mutated pathways. The allelic association test suggested that the intronic variants in HLTF and RAD52 gene significantly associated (P < 0.05) with the risk (OR > 5), while intronic variants in PARP4, RECQL5, EXO1 and PER1 genes and exonic variant in TDP2 gene showed protection (OR < 1) for HNC. MDR analysis proposed the exonic variants in MSH6, BRCA2, PALB2 and TP53 genes and intronic variant in RECQL5 genetic region working together during certain phase of DNA repair mechanism for HNC causation. In addition, other intronic and 3'UTR variations caused modifications in the transcription factor binding sites and miRNA target sites associated with HNC. Large-scale validation in NE Indian population, in-depth structure prediction and subsequent simulation of our recognized polymorphisms is necessary to identify true causal variants related to HNC.

The rs3957357C>T SNP in GSTA1 Is Associated with a Higher Risk of Occurrence of Hepatocellular Carcinoma in European Individuals

Glutathione S-transferases (GSTs) detoxify toxic molecules by conjugation with reduced glutathione and regulate cell signaling. Single nucleotide polymorphisms (SNPs) of GST genes have been suggested to affect GST functions and thus to increase the risk of human hepatocellular carcinoma (HCC). As GSTA1 is expressed in hepatocytes and the rs3957357C>T (TT) SNP is known to downregulate GSTA1 mRNA expression, the aims of this study were: (i) to explore the relationship between the TT SNP in GSTA1 and the occurrence of HCC; (ii) to measure GSTA1 mRNA expression in HCCs. For that purpose, we genotyped non-tumor-tissue-derived DNA from 48 HCC patients and white-blood-cell-derived DNA from 37 healthy individuals by restriction fragment length polymorphism (RFLP). In addition, expression of GSTA1 mRNA was assessed by real-time PCR in 18 matching pairs of HCCs and non-tumor livers. Survival analysis was performed on an annotated microarray dataset containing 247 HCC patients (GSE14520). The GSTA1 TT genotype was more frequent in HCC than in non-HCC patients (27% versus 5%, respectively), suggesting that individuals carrying this genotype could be associated with 2-fold higher risk of developing HCCs (odds ratio = 2.1; p = 0.02). Also, we found that GSTA1 mRNA expression was lower in HCCs than in non-tumor livers. HCCs expressing the highest GSTA1 mRNA levels were the smallest in size (R = -0.67; p = 0.007), expressed the highest levels of liver-enriched genes such as ALB (albumin, R = -0.67; p = 0.007) and COL18A1 (procollagen type XVIII, R = -0.50; p = 0.03) and showed the most favorable disease-free (OR = 0.54; p<0.001) and overall (OR = 0.56; p = 0.006) outcomes. Moreover, GSTA1 was found within a 263-gene network involved in well-differentiated hepatocyte functions. In conclusion, HCCs are characterized by two GSTA1 features: the TT SNP and reduced GSTA1 gene expression in a context of hepatocyte de-differentiation.

Association of the recurrence and canceration rate of vocal leukoplakia with interleukin-10 promoter variants over a 2-year period

Conclusion This study indicates that IL-10 promoter polymorphism variants, smoking, and alcohol consumption increase the risk of recurrence and canceration in vocal leukoplakia. Objective This prospective, clinical trial was performed to evaluate the association of interleukin (IL)-10 promoter polymorphism variants and canceration and recurrence rates in vocal leukoplakia (a pre-cancerous laryngeal carcinoma lesion) over a 2-year period. Participants and method Sixty-one post-operative patients with vocal leukoplakia were enrolled in this prospective, observational study and genotyped for the IL-10 promoter gene (IL-10-1082 A/G, -819 T/C and -592 A/C) using pyrosequencing, and responded to a 2-year follow-up survey. Recurrence and canceration rates were used to evaluate the association between the genotype variants and the clinical outcome. Results There was an increased canceration rate in the variant genotype group compared to that in the normal genotype group in the 2-year follow-up period (18.4% vs 0%, p-value = 0.038). Compared with the non-smoker group, the smoker group had a higher recurrence rate of vocal leukoplakia (29.3% vs 5%, p-value =0.044). Likewise, the recurrence rate in the alcohol consumption group was also higher (30.6% vs 8%, p-value =0.034). The percentage of cancerization in the alcohol consumption group was significantly higher than that in the non-alcohol consumption group (19.4% vs 0%, p-value =0.035).

Promoter Hypermethylation Profiling Identifies Subtypes of Head and Neck Cancer with Distinct Viral, Environmental, Genetic and Survival Characteristics

BACKGROUND

Epigenetic and genetic alteration plays a major role to the development of head and neck squamous cell carcinoma (HNSCC). Consumption of tobacco (smoking/chewing) and human papilloma virus (HPV) are also associated with an increase the risk of HNSCC. Promoter hypermethylation of the tumor suppression genes is related with transcriptional inactivation and loss of gene expression. We investigated epigenetic alteration (promoter methylation of tumor-related genes/loci) in tumor tissues in the context of genetic alteration, viral infection, and tobacco exposure and survival status.

METHODOLOGY

The study included 116 tissue samples (71 tumor and 45 normal tissues) from the Northeast Indian population. Methylation specific polymerase chain reaction (MSP) was used to determine the methylation status of 10 tumor-related genes/loci (p16, DAPK, RASSF1, BRAC1, GSTP1, ECAD, MLH1, MINT1, MINT2 and MINT31). Polymorphisms of CYP1A1, GST (M1 & T1), XRCC1and XRCC2 genes were studied by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and multiplex-PCR respectively.

PRINCIPAL FINDINGS

Unsupervised hierarchical clustering analysis based on methylation pattern had identified two tumor clusters, which significantly differ by CpG island methylator phenotype (CIMP), tobacco, GSTM1, CYP1A1, HPV and survival status. Analyzing methylation of genes/loci individually, we have found significant higher methylation of DAPK, RASSF1, p16 and MINT31 genes (P = 0.031, 0.013, 0.031 and 0.015 respectively) in HPV (+) cases compared to HPV (-). Furthermore, a CIMP-high and Cluster-1 characteristic was also associated with poor survival.

CONCLUSIONS

Promoter methylation profiles reflecting a correlation with tobacco, HPV, survival status and genetic alteration and may act as a marker to determine subtypes and patient outcome in HNSCC.

Polycyclic aromatic hydrocarbons and cytochrome P450 in HIV pathogenesis

High prevalence of cigarette smoking in HIV patients is associated with increased HIV pathogenesis and disease progression. While the effect of smoking on the occurrence of lung cancer has been studied extensively, the association between smoking and HIV pathogenesis is poorly studied. We have recently shown the possible role of cytochrome P450 (CYP) in smoking/nicotine-mediated viral replication. In this review, we focus on the potential role of CYP pathway in polycyclic aromatic hydrocarbons (PAH), important constituents of cigarette smoke, mediated HIV pathogenesis. More specifically, we will discuss the role of CYP1A1 and CYP1B1, which are the major PAH-activating CYP enzymes. Our results have shown that treatment with cigarette smoke condensate (CSC) increases viral replication in HIV-infected macrophages. CSC contains PAH, which are known to be activated by CYP1A1 and CYP1B1 into procarcinogens/toxic metabolites. The expression of these CYPs is regulated by aryl hydrocarbon receptors (AHR), the cellular target of PAH, and an important player in various diseases including cancer. We propose that PAH/AHR-mediated CYP pathway is a novel target to develop new interventions for HIV positive smokers.