hTERT gene amplification and clinical significance in pleural effusions of patients with lung cancer

PIF1 Affects the Proliferation and Apoptosis of Cervical Cancer Cells by Influencing TERT

Introduction

Cervical cancer is a common malignancy in female and it is a serious disease threatening women’s lives. We aimed to explore whether PIF1 helicase expression could affect cell proliferation and apoptosis, and whether its mechanisms were related to the expression and activity of TERT.

Methods

Western blot analysis was used to detect the expressions of PIF1 and TERT in End1/E6E7, Hela, SiHa, Ca-Ski and C-33A cells and apoptosis-related proteins (Bax, Bcl-2 and Caspase-3). RT-qPCR and Western blot analysis determined the expressions of PIF1 and TERT after transfection. After transfection or cycloastragenol (CAG) treatment, the proliferation, apoptosis, cell cycle and telomerase TERT activity were analyzed by CCK-8 assay, flow cytometry analysis and ELISA assay. Co-immunoprecipitation assay was used to verify the interactions between PIF1 and TERT.

Results

The expressions of PIF1 and TERT in End1/E6E7, Hela, SiHa, Ca-Ski and C-33A cells were increased. As PIF1 and TERT expressions in C-33A cells showed the minimum increase, C-33A cells were chosen for the next study. PIF1 interference inhibited the proliferation, decreased the ratio of G2/M phase and promoted apoptosis of transfected cells, and PIF1 interference promoted the expressions of Bax and Caspase-3 and suppressed the Bcl-2 expression. Furthermore, PIF1 interference down-regulated the telomerase activity. The effect of PIF1 overexpression was opposite to that of PIF1 interference. Co-immunoprecipitation assay demonstrated that PIF1 could combine with TERT. CAG treatment effectively reversed the effect of PIF1 interference on proliferation, cycle and apoptosis of C-33A cells transfected with shRNA-PIF1. Moreover, CAG treatment increased the expressions of PIF1 and TERT.

Discussion

PIF1 helicase could promote the proliferation and suppress the apoptosis of cervical cancer cells by down-regulating the activity of telomerase TERT.

Tankyrase 2 (TNKS2) polymorphism associated with risk in developing non-small cell lung cancer in a Chinese population

OBJECTIVES

We investigated the association between poly(ADP-ribose) polymerase Tankyrase 2 (TNKS2) single-nucleotide polymorphisms (SNPs) and the risk of developing non-small cell lung cancer (NSCLC) in a Han Chinese population.

METHODS

Five-hundred NSCLC cases and 500 healthy controls were genotyped for four TNKS2 tagging SNPs (rs1538833, rs1538833, rs1340420, and rs1340420). The association between genotype and NSCLC risk was evaluated by computing the odds ratio (OR) and 95% confidence interval (CI) using multivariate unconditional logistic regression analyses.

RESULTS

Individual alleles of the four TNKS2 SNPs were not associated with NSCLC risk in the studied Chinese population. However, patients carrying TNKS2 rs1340420 G/G and A/G genotypes were associated with a lower risk of developing NSCLC and adenocarcinoma (OR=0.14; 95% CI=0.02-1.15 and OR=0.11; 95% CI=0.03-0.91, respectively), whereas females patients homozygous for the TNKS2 rs1770474 T allele, a rare type, were associated with a higher risk of developing squamous-cell carcinoma (SCC) (OR=4.67; 95% CI=0.87-25.01).

CONCLUSION

TNKS2 rs1340420 SNP was associated with lower NSCLC risk, whereas rs1770474 SNP was associated with higher SCC risk, suggesting that these two SNPs may be useful predictors of risk of developing NSCLC and SCC in this Chinese population.

Genetic polymorphisms of TERT and CLPTM1L, cooking oil fume exposure, and risk of lung cancer: a case-control study in a Chinese non-smoking female population

Genetic polymorphisms of telomerase reverse transcriptase (TERT) and cleft lip and palate transmembrane 1-like (CLPTM1L) genes in chromosome 5p15.33 region were previously identified to influence the risks of lung cancer. This study aimed to investigate the association between polymorphisms in TERT and CLPTM1L genes with the risk of lung cancer, as well as the interaction of the polymorphisms and the environmental risk factors in Chinese non-smoking females. A hospital-based case-control study of 524 cases and 524 controls was conducted. Two polymorphisms were determined by Taqman allelic discrimination method. The statistical analyses were performed mostly with SPSS. This study showed that the individuals with the TG or GG genotypes of TERT polymorphism (rs2736100) were at an increased risk for lung cancer compared with those carrying the TT genotype in Chinese non-smoking females [adjusted odds ratios (ORs) were 1.44 and 1.85, 95 % confidence intervals (CIs) were 1.09-1.90 and 1.29-2.65, respectively]. The stratified analysis suggested that increased risks were more pronounced in lung adenocarcinoma (corresponding ORs were 1.71 and 2.30, 95 % CIs were 1.25-2.35 and 1.54-3.43). Our results showed that exposure to cooking oil fume was associated with increased risk of lung cancer in Chinese non-smoking females (adjusted ORs 1.59, 95 % CI 1.13-2.23). However, we did not observe a significant interaction of cooking oil fume and TERT polymorphism on lung cancer among Chinese non-smoking females. TERT polymorphism (rs2736100) might be a genetic susceptibility factor for lung cancer in non-smoking females in China.

TERT rs2736100 polymorphism contributes to lung cancer risk: a meta-analysis including 49,869 cases and 73,464 controls

Some studies investigated the association of TERT rs2736100 polymorphism with lung cancer (LC). But the results were not consistent. We performed a meta-analysis to examine the association between rs2736100 and LC. Databases including PubMed, EMBASE, Wanfang, and China National Knowledge Infrastructure (CNKI) were searched. Data were extracted, and pooled odds ratios (ORs) with 95 % confidence intervals (CIs) were calculated. A total of 19 studies including 49,869 cases and 73,464 controls were involved in this meta-analysis. Overall, a significant association between TERT rs2736100 polymorphism and LC risk was observed (OR=1.23, 95 % CI 1.18-1.28, P<0.00001). This polymorphism was also significantly associated with LC risk in Asians (OR=1.27, 95 % CI 1.22-1.33, P<0.00001), Caucasians (OR=1.14, 95 % CI 1.10-1.18, P<0.00001), female patients (OR=1.37, 95 % CI 1.24-1.51, P<0.00001), male patients (OR=1.23, 95 % CI 1.15-1.31, P<0.00001), adenocarcinoma patients (OR=1.35, 95 % CI 1.28-1.41, P<0.00001), squamous cell carcinoma patients (OR=1.13, 95 % CI 1.04-1.21, P=0.002), small cell lung cancer patients (OR=1.09, 95 % CI 1.03-1.16, P=0.004), current smokers (OR=1.22, 95 % CI 1.17-1.27, P<0.00001), former smokers (OR=1.14, 95 % CI 1.08-1.21, P<0.0001), and never smokers (OR=1.37, 95 % CI 1.31-1.43, P<0.00001), respectively. This meta-analysis suggested that TERT rs2736100 polymorphism was a risk factor for LC.

Silencing tankyrase and telomerase promotes A549 human lung adenocarcinoma cell apoptosis and inhibits proliferation

Telomeres are the end structures of chromosomes in mammalian cells; they play a pivotal role in maintaining the stability of the chromosome and become shorter with each cell division. However, several types of tumor cells express telomerase in very high levels to overcome this crisis and achieve the ability to proliferate endlessly. The telomerase inhibitors can partly inhibit tumor cell proliferation and promote apoptosis, but their roles are only limited. Tankyrase is a poly(ADP-ribose) polymerase which has synergistic effect on telomerase, and is expressed in lung cancer cells in high levels. In the present study, antisense oligonucleotides of telomerase (ashTERT) and tankyrase (asTANKS) were used as specific inhibitors to silence the expression of target genes in A549 human lung adenocarcinoma cells by transfection. The results showed that ashTERT and asTANKS suppressed the expression of telomerase and tankyrase significantly; both inhibited the activity of telomerase and the combination group achieved better effect, but only ashTERT shortened the length of telomeres, asTANKS did not. Further studies showed that ashTERT and asTANKS-promoted A549 apoptosis was not mediated by downregulation of the expression of the anti-apoptotic gene BCL-2 or upregulation of the expression of the pro-apoptotic gene BAX, but by adjusting the two isoforms proportion of myeloid cell leukemia-1 (MCL-1) which can interact with tankyrase directly. MCL-1short (MCL-1S), a pro-apoptotic gene, increased more than MCL-1Long (MCL-1L) which is an anti-apoptotic gene, leading to A549 cell apoptosis and a similar result was obtained in nude mice in vivo. The present study suggests that combination of the inhibitors of telomerase and tankyrase can be used as a strategy for the treatment of lung cancer in humans.

Genetic polymorphisms of TERT and CLPTM1L and risk of lung cancer--a case-control study in a Chinese population

BACKGROUND/OBJECTIVES

Genetic variants of telomerase reverse transcriptase (TERT) and cleft lip and palate trans-membrane 1 like (CLPTM1L) genes in chromosome 5p15.33 region were previously identified to influence the susceptibility to lung cancer. We examined the association of single nucleotide polymorphisms (SNPs) in TERT and CLPTM1L genes with lung cancer and explored their potential modifying effects on the relationship between environmental risk factors and lung cancer in a Chinese population.

METHODS

We genotyped rs2736100 (TERT) and rs401681 (CLPTM1L) SNPs in a case-control study with 399 lung cancer cases and 466 controls form Taiyuan, China. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using unconditional logistic regression models. Potential confounders were controlled for in the adjusted models.

RESULTS

We found that the GG genotype of TERT was positively associated with lung cancer (OR=1.47, 95% CI: 1.00-2.16). The association was stronger in participants older than 60years, exposed to low indoor air pollution and adenocarcinoma and squamous cell carcinoma (SCC) in recessive model analysis. The GA genotype of CLPTM1L was inversely associated with lung cancer (OR=0.72, 95% CI: 0.54-0.97). The association was stronger in participants 60 years old or younger, males, heavy smokers, exposed to low indoor air pollution and SCC in dominant model analysis. Individuals carrying both TERT and CLPTM1L risk genotypes had higher risk of lung cancer (OR=1.80, 95% CI: 1.15-2.82). Significant interaction was observed between CLPTM1L and indoor air pollution in association with lung cancer.

CONCLUSIONS

Our results reiterate that genetic variants of TERT and CLPTM1L contribute to lung cancer susceptibility in Chinese population. These associations need to be verified in larger and different populations.