Dysfunction of mitochondria due to environmental carcinogens in nasopharyngeal carcinoma in the ethnic group of Northeast Indian population

Expression and functional implications of YME1L in nasopharyngeal carcinoma

Mitochondria play a crucial role in the progression of nasopharyngeal carcinoma (NPC). YME1L, a member of the AAA ATPase family, is a key regulator of mitochondrial function and has been implicated in various cellular processes and diseases. This study investigates the expression and functional significance of YME1L in NPC. YME1L exhibits significant upregulation in NPC tissues from patients and across various primary human NPC cells, while its expression remains relatively low in adjacent normal tissues and primary nasal epithelial cells. Employing genetic silencing through the shRNA strategy or knockout (KO) via the CRISPR-sgRNA method, we demonstrated that YME1L depletion disrupted mitochondrial function, leading to mitochondrial depolarization, reactive oxygen species (ROS) generation, lipid peroxidation, and ATP reduction within primary NPC cells. Additionally, YME1L silencing or KO substantially impeded cell viability, proliferation, cell cycle progression, and migratory capabilities, concomitant with an augmentation of Caspase-apoptosis activation in primary NPC cells. Conversely, ectopic YME1L expression conferred pro-tumorigenic attributes, enhancing ATP production and bolstering NPC cell proliferation and migration. Moreover, our findings illuminate the pivotal role of YME1L in Akt-mTOR activation within NPC cells, with Akt-S6K phosphorylation exhibiting a significant decline upon YME1L depletion but enhancement upon YME1L overexpression. In YME1L-silenced primary NPC cells, the introduction of a constitutively-active Akt1 mutant (caAkt1, at S473D) restored Akt-S6K phosphorylation, effectively ameliorating the inhibitory effects imposed by YME1L shRNA. In vivo studies revealed that intratumoral administration of YME1L-shRNA-expressing adeno-associated virus (AAV) curtailed subcutaneous NPC xenograft growth in nude mice. Furthermore, YME1L downregulation, concurrent with mitochondrial dysfunction and ATP reduction, oxidative injury, Akt-mTOR inactivation, and apoptosis induction were evident within YME1L-silenced NPC xenograft tissues. Collectively, these findings shed light on the notable pro-tumorigenic role by overexpressed YME1L in NPC, with a plausible mechanism involving the promotion of Akt-mTOR activation.

Associations between ALDH Genetic Variants, Alcohol Consumption, and the Risk of Nasopharyngeal Carcinoma in an East Asian Population

Nasopharyngeal carcinoma (NPC) and alcohol flush syndrome are thought to be strongly influenced by genetic factors and are highly prevalent amongst East Asians. Diminished activity of aldehyde dehydrogenase (ALDH), a major enzyme in the alcohol-metabolizing pathway, causes the flushing syndrome associated with alcoholic consumption. The genetic effect of ALDH isoforms on NPC is unknown. We therefore investigated the association between the genetic polymorphisms of all 19 ALDH isoforms and NPC among 458 patients with NPC and 1672 age- and gender-matched healthy controls in Taiwan. Single-nucleotide polymorphisms (SNPs) located between the 40,000 base pairs upstream and downstream of the 19 ALDH isoform coding regions were collected from two genome-wise association studies conducted in Taiwan and from the Taiwan Biobank. Thirteen SNPs located on ALDH4A1, ALDH18A1, ALDH3B2, ALDH1L2, ALDH1A2, and ALDH2 Glu487Lys (rs671) were associated with NPC susceptibility. Stratification by alcohol status revealed a cumulative risk effect for NPC amongst drinkers and non-drinkers, with odds ratios of 4.89 (95% confidence interval 2.15–11.08) and 3.57 (1.97–6.47), respectively. A synergistic effect was observed between SNPs and alcohol. This study is the first to report associations between genetic variants in 19 ALDH isoforms, their interaction with alcohol consumption and NPC in an East Asian population.

Association Between Mitochondrial DNA Copy Number and Head and Neck Squamous Cell Carcinoma: A Systematic Review and Dose-Response Meta-Analysis

Background

The association between mitochondrial DNA (mtDNA) copy number and head and neck squamous cell carcinoma (HNSCC) risk remains unclear. Therefore, we aimed to evaluate the relationship between mtDNA copy number and HNSCC risk.

Material/Methods

We searched PubMed, Web of Science, and EMBASE until August 2020. Studies that assessed the association between mtDNA copy number and HNSCC as the outcome of interest were included. We performed a 2-class and dose-response meta-analysis to assess the association between cancer risk and mtDNA.

Results

Eight articles (2 cohort studies and 6 case-control studies) with a total of 3913 patients were included in our meta-analysis. The overall results showed that mean mtDNA copy number level from 9 studies was 0.71 higher in patients with cancer than in non-cancer controls (the standardized mean differences (SMD) 0.71, 95% CI: 0.28–1.15, P<0.001). However, when 4 studies were pooled by dichotomizing mtDNA copy number at the median value into high- and low-content groups, no significant association between mtDNA content and overall cancer risk was found (odds ratio (OR)=0.87, 95% CI: 0.52–1.44, P=0.584). Furthermore, we observed a non-linear association from 3 studies between increased mtDNA copy number levels (P for nonlinearity <0.001).

Conclusions

The elevated mtDNA copy number could predict the risk of HNSCC as a biomarker. Moreover, there was non-linear relationship of risk between HNSCC and mtDNA copy number.

Role of Mitochondrial DNA (mtDNA) Variations in Cancer Development: A Systematic Review

mtDNA is the closed circular, ds-DNA present in mitochondria of eukaryotic cells and are inherited maternally. Besides being the power house of the cell, mitochondria are also responsible for the regulation of redox homeostasis, signaling, metabolism, immunity, survival and apoptosis. Lack of a 'Systematic Review' on mtDNA variations and cancers encouraged us to perform the present study. Pubmed', 'Embase' and 'Cochrane Library' databases were searched using keywords 'Mitochondrial DNA' OR 'mtDNA' OR 'mDNA' AND 'polymorphism' AND 'cancer' AND 'risk' to retrieve literature. Polymorphisms occupy first rank among mtDNA variations followed by CNV, MSI, mutations and hold a great potential to emerge as key predictors for human cancers.

Association Between Alcohol Consumption and Risk of Nasopharyngeal Carcinoma: A Comprehensive Meta-Analysis of Epidemiological Studies

BACKGROUND

Alcohol consumption is increasing all over the world, but whether it is an independent factor affecting the occurrence of nasopharyngeal carcinoma (NPC) is inconsistent in many studies. We aimed to explore the association between alcohol consumption and NPC risk by integrating existing evidence in a meta-analysis.

METHODS

We searched for relevant articles published up to August 2018 in PubMed, Cochrane Library, Web of Science, and China National Knowledge infrastructure (CNKI). The Newcastle-Ottawa scale was used to assess the quality of the included studies. Odds ratios (ORs) or relative risks were pooled to estimate the associations between alcohol consumption and NPC risk.

RESULTS

The meta-analysis of cohort studies showed no significant association between alcohol consumption and NPC, but pooled results from case-control studies indicated that ever drinking increased the probability of NPC versus nondrinking (OR = 1.10; 95% confidence interval [CI]: 1.01, 1.19). As compared with nondrinkers, high-frequency drinking (≥7 times/wk) increased the NPC probability (OR = 1.29; 95% CI: 1.05, 1.53) and low-frequency drinking (<7 times/wk) decreased the probability (OR = 0.77; 95% CI: 0.60, 0.94), as did shorter duration of drinking (<20 years) (OR = 0.64; 95% CI: 0.49, 0.79). On subgroup analyses, significant pooled results were observed for studies with high quality, with hospital-based controls and with adjustment for confounding factors, smoking, age, and sex.

CONCLUSIONS

The risk of NPC may increase with alcohol consumption. Ever drinking increased the risk versus nondrinking. Additionally, high-frequency drinking increased the risk, but low-frequency drinking decreased it to some extent. Further intensive studies based on well-designed methods are needed to examine the association.

Nasopharyngeal Carcinoma (NPC) Risk Factors: A Systematic Review and Meta-Analysis of the Association with Lifestyle, Diets, Socioeconomic and Sociodemographic in Asian Region

Objective:

Risk factors of nasopharyngeal carcinoma (NPC) have been linked with diets, life style and viral infections. NPC is more rampant in Asian populations than non-Asian countries. Our study aims to assess the validity of the suggestions provided by multiple case control studies demonstrating that salted fish consumption, smoking and alcohol consumption are associated with the risk of NPC in Asia.

Methods:

Search for related literature on salted fish, smoking and alcohol consumption were performed via Science Direct, PubMed databases and Google Scholar. Articles included in this study were from 2009 to 2017, with specific focus on salted fish, smoking and alcohol consumption as risk factors of NPC. This study excluded all articles published prior to 2009 and articles involving other cancers. Data were extracted independently by two different researchers and harmonized. Meta-analysis was conducted on the obtained data, by using R package Meta to create funnel and forest plots.

Results:

The meta-analysis revealed that salted fish, smoking and alcohol consumption were significantly associated to NPC risk with random effect model score showing OR of 1.41 at 95% confidence interval (CI) of 1.13-1.75 (P<0.01), OR of 1.89 at 95 % CI of 1.49 – 2.38, and OR: 1.42 at 95 % CI of 1.23 – 1.65 respectively. Our results also revealed significant association of salted meat, salted vegetables, house type, wood dust exposure associated with NPC risk with p values less than 0.05.

Conclusion:

This study proposes that salted fish intake, smoking and alcohol consumption might be linked to NPC risk in Asians. Further studies are necessary to ascertain the molecular mechanisms and clarify if the associated path that could function as therapeutic target.

Diagnostic potential of methylated DAPK in brushing samples of nasopharyngeal carcinoma

Background

The death-associated protein kinase (DAPK) gene is an important member of the apoptotic pathway and is inactivated by abnormal methylation in numerous cancers, including nasopharyngeal carcinoma (NPC). However, the diagnostic value of DAPK methylation in brushing samples and tissue samples of NPC remains unclear.

Methods

We conducted a systematic meta-analysis based on 17 studies (including 386 tissue cases, 233 brushing cases, and 296 blood cases).

Results

Our results revealed an association between methylated DAPK and increased risk of NPC in blood, brushing, and tissue samples. In addition, the comparison of the pooled sensitivity, specificity, and area under the curve of methylated DAPK in brushing and tissue samples demonstrated the non-inferior effectiveness of methylated DAPK in brushing samples to monitor the development of NPC.

Metabolic Phase I (CYPs) and Phase II (GSTs) Gene Polymorphisms and Their Interaction with Environmental Factors in Nasopharyngeal Cancer from the Ethnic Population of Northeast India

Multiple genetic and environmental factors and their interaction are believed to contribute in the pathogenesis of Nasopharyngeal Cancer (NPC). We investigate the role of Metabolic Phase I (CYPs) and Phase II (GSTs) gene polymorphisms, gene-gene and gene-environmental interaction in modulating the susceptibility to NPC in Northeast India. To determine the association of metabolic gene polymorphisms and environmental habits, 123 cases and 189 controls blood/swab samples were used for PCR and confirmed by Sanger sequencing. Analysis for GSTM1 and GSTT1 gene polymorphism was done by multiplex PCR. The T3801C in the 3'- flanking region of CYP1A1 gene was detected by PCR-RFLP method. The Logistic regression analysis was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI). The GSTM1 null genotype alone (OR = 2.76) was significantly associated with NPC risk (P < 0.0001). The combinations of GSTM1 null and GSTT1 null genotypes also higher, 3.77 fold (P < 0.0001), risk of NPC, while GSTM1 null genotype along with CYP1A1 T3801C TC + CC genotype had 3.22 (P = 0.001) fold risk. The most remarkable risk was seen among individual carrying GSTM1 null, GSTT1 null genotypes and CYP1A1 T3801C TC + CC genotypes (OR = 5.71, P = 0.001). Further; analyses demonstrate an enhanced risk of NPC in smoked meat (OR = 5.56, P < 0.0001) and fermented fish consumers (OR = 5.73, P < 0.0001) carrying GSTM1 null genotype. An elevated risk of NPC was noted in smokers (OR = 12.67, P < 0.0001) and chewers (OR = 5.68, P < 0.0001) with GSTM1 null genotype. However, smokers had the highest risk of NPC among individuals carrying GSTT1 null genotype (OR = 4.46, P = 0.001) or CYP1A1 T3801C TC + CC genotype (OR = 7.13, P < 0.0001). The association of null genotypes and mutations of metabolic neutralizing genes along with the environmental habits (tobacco smokers and chewers, smoke meat, fermented fishes) can be used as a possible biomarker for early detection and preventive measure of NPC.

Altered mitochondrial DNA copy number contributes to human cancer risk: evidence from an updated meta-analysis

Accumulating epidemiological evidence indicates that the quantitative changes in human mitochondrial DNA (mtDNA) copy number could affect the genetic susceptibility of malignancies in a tumor-specific manner, but the results are still elusive. To provide a more precise estimation on the association between mtDNA copy number and risk of diverse malignancies, a meta-analysis was conducted by calculating the pooled odds ratios (OR) and the 95% confidence intervals (95% CI). A total of 36 case-control studies involving 11,847 cases and 15,438 controls were finally included in the meta-analysis. Overall analysis of all studies suggested no significant association between mtDNA content and cancer risk (OR = 1.044, 95% CI = 0.866–1.260, P = 0.651). Subgroup analyses by cancer types showed an obvious positive association between mtDNA content and lymphoma and breast cancer (OR = 1.645, 95% CI = 1.117–2.421, P = 0.012; OR = 1.721, 95% CI = 1.130–2.622, P = 0.011, respectively), and a negative association for hepatic carcinoma. Stratified analyses by other confounding factors also found increased cancer risk in people with drinking addiction. Further analysis using studies of quartiles found that populations with the highest mtDNA content may be under more obvious risk of melanoma and that Western populations were more susceptible than Asians.

Influence of the CYP1A1 T3801C Polymorphism on Tobacco and Alcohol-Associated Head and Neck Cancer Susceptibility in Northeast India

BACKGROUND

Tobacco and alcohol contain or may generate carcinogenic compounds related to cancers. CYP1A1 enzymes act upon these carcinogens before elimination from the body. The aim of this study was to investigate whether CYP1A1 T3801C polymorphism modulates the relationship between tobacco and alcohol- associated head and neck cancer (HNC) susceptibility among the northeast Indian population.

MATERIALS AND METHODS

One hundred and seventy histologically confirmed HNC cases and 230 controls were included within the study. The CYP1A1 T3801C polymorphism was determined using PCR-RFLP, and the results were confirmed by DNA sequencing. Logistic regression (LR) and multifactor dimensionality reduction (MDR) approaches were applied for statistical analysis.

RESULTS

The CYP1A1 CC genotype was significantly associated with HNC risk (P=0.045). A significantly increased risk of HNC (OR=6.09; P<0.0001) was observed in individuals with combined habits of smoking, alcohol drinking and tobacco-betel quid chewing. Further, gene-environment interactions revealed enhanced risks of HNC among smokers, alcohol drinkers and tobacco-betel quid chewers carrying CYP1A1 TC or CC genotypes. The highest risk of HNC was observed among smokers (OR=7.55; P=0.009) and chewers (OR=10.8; P<0.0001) carrying the CYP1A1 CC genotype. In MDR analysis, the best model for HNC risk was the three-factor model combination of smoking, tobacco-betel quid chewing and the CYP1A1 variant genotype (CVC=99/100; TBA=0.605; P<0.0001); whereas interaction entropy graphs showed synergistic interaction between tobacco habits and CYP1A1.

CONCLUSIONS

Our results confirm that the CYP1A1 T3801C polymorphism modifies the risk of HNC and further demonstrated importance of gene-environment interaction.

Evaluation of Risk Factors for Nasopharyngeal Carcinoma in a High-risk Area of India, the Northeastern Region

Northeastern India is a major nasopharyngeal carcinoma (NPC) high risk-area although the rest of the country has very low incidence. A case-control study of 105 NPC cases and 115 controls was conducted to identify the potential risk factors for NPC development in this region. Information was collected by interviewer about socio-demographic characteristics, cigarette smoking, alcohol consumption, dietary history, occupational history, and a family history of cancer. Epstein-Barr viral load was assayed from the blood DNA by real time PCR. Associations between GSTs genotypes, cytochrome P450 family including CYP1A1, CYP2E1 and CYP2A6 polymorphisms and susceptibility to relationship between the diseases were studied using PCR-RFLP assay. Results indicate that Epstein-Barr virus load was significantly higher in patients compared to controls (p<0.0001). Furthermore, concentration of blood EBV-DNA was significantly higher in advanced stage disease (Stage III and IV) than in early stage disease (Stage I and II) (p<0.05). Presence of CYP2A6 variants that reduced the enzyme activity was significantly less frequent in cases than controls. Smoked meat consumption, exposure to smoke, living in poorly ventilated house and alcohol consumption were associated with NPC development among the population of Northeastern India. Thus, overall our study revealed that EBV viral load and genetic polymorphism of CYP2A6 along with living practices which include smoked meat consumption, exposure to smoke, living in poorly ventilated houses and alcohol consumption are the potential risk factors of NPC in north eastern region of India. Understanding of the risk factors and their role in the etiology of NPC are helpful forpreventive measures and screening.