Smoking correlates with increased cytoskeletal protein-related coding region mutations in the lung and head and neck datasets of the cancer genome atlas

4NQO enhances differential activation of DNA repair proteins in HPV positive and HPV negative HNSCC cells

Tobacco exposure and human papillomavirus (HPV) infection are among the main risk factors for the development of head and neck squamous cell carcinoma (HNSCC). Interestingly, recent studies show that tumors from HPV positive (HPV+) smokers and non-smokers have similar mutational profiles, which suggests that HPV could prevent mutation induction or accumulation in the intermediate risk group composed of HPV+ smokers. Hence, we tested this observation by analyzing the effects of 4-Nitroquinoline N-oxide (4NQO), a mutagen and smoking mimetic, in NOK (normal oral keratinocytes), NOK^E6.E7 (NOK cells transfected with E6.E7 oncogenes of HPV), HPV+ and HPV negative (HPV-) HNSCC cells. Oxidative DNA damage, γH2AX foci formation, DNA repair protein activation, cell cycle phase analysis, apoptotic cell death, cell viability and clonogenic cell survival were analyzed after 4NQO treatment in NOK, NOK^E6.E7, HPV+ and HPV- HNSCC cells. 4NQO increased oxidative base damage and γH2AX foci formation in NOK^E6.E7, HPV+ and HPV- HNSCC cells. Phosphorylation of homologous recombination (HR) repair proteins was higher in NOK^E6.E7 and HPV+ HNSCC cells compared to NOK and HPV- HNSCC cells respectively. HPV+ and HPV- HNSCC cells showed differential activation of cell cycle regulatory proteins, increased apoptosis, and decreased cell viability upon 4NQO-induced DNA damage. Taken together, 4NQO (a smoking mimetic), induced higher activation of HR repair in HPV+ HNSCC cells compared to HPV- HNSCC cells. This may allow for increased mutational resistance and help explain why HPV+ smokers have a worse prognosis than HPV+ non-smokers.

Smoking is Associated with Lung Adenocarcinoma and Lung Squamous Cell Carcinoma Progression through Inducing Distinguishing lncRNA Alterations in Different Genders

BACKGROUND

Smoking participates in pathogenesis of lung cancer. Long non-coding RNAs (lncRNAs) play some specific roles during development of lung cancers.

OBJECTIVE

To investigate effects of smoking on lncRNA alterations in lung cancer.

METHODS

There are 522 lung adenocarcinoma (LUAD) and 504 lung squamous cell carcinoma (LUSC) participants. Clinical and lncRNA genetic data were downloaded from The Cancer Genome Atlas (TCGA) database. LncRNA alterations were analyzed in lung cancer patients. Smoking category and packs were evaluated. Correlations between smoking and LncRNA alterations were analyzed. Kaplan-Meier analysis was performed to determine overall survival and disease free survival.

RESULTS

There are more non-smokers in LUSC than in LUAD. In both LUAD and LUSC, smoking could increase total mutation counts and fraction of copy number alterations. Smoking index positively correlated with total mutations in LUAD, but not in LUSC. Smoking could trigger lncRNA alterations both in LUAD and LUSC. Smoking regulated different lncRNA between male and female. EXOC3-AS1 and LINC00603 alterations were positively correlated with smoking index in male LUAD smokers. In female LUAD smokers, smoking index was positively correlated with SNHG15, TP53TG1 and LINC01600 and negatively with LINC00609 and PTCSC3. In both male and female LUSC patients, smoking increased or decreased several lncRNA alterations. DGCR5 alteration increased in male LUSC than in female LUSC patients. In female LUSC patients, LOH12CR2 alteration was positively correlated with smoking index.

CONCLUSIONS

Smoking promoted LUAD and LUSC development by affecting different lncRNA alterations in different genders.

A Novel Signature for Predicting Prognosis of Smoking-Related Squamous Cell Carcinoma

Tobacco smoking is an established risk factor for squamous cell carcinoma (SCC). We obtained smoking-related SCC, including cervical SCC (CSCC), esophageal SCC (ESCC), head and neck SCC (HNSC), and lung SCC (LUSC), from The Cancer Genome Atlas (TCGA) database to investigate the association between smoking status (reformed and current smoking) and prognosis. We found that reformed smokers had a better prognosis than current smokers in CSCC (p = 0.003), HNSC (p = 0.019), and LUSC (p < 0.01) cohorts. Then, we selected LUSC cohorts as the training cohort and other SCC cohorts as the test cohorts. Function analysis revealed that homologous recombination (HR) was the most significant pathway involved in smoking-induced LUSC. Moreover, the effect of cross-talk between the smoking status and HR deficiency (HRD) on the prognosis was further evaluated, revealing that quitting smoking with high HRD scores could significantly improve patients’ prognosis (p < 0.01). To improve prognosis prediction and more effectively screen suitable populations for platinum drugs and poly-ADP-ribose polymerase (PARP) inhibitors, we constructed a risk score model using smoking- and HRD-related genes in LUSC. The risk score model had high power for predicting 2-, 3-, and 5-year survival (p < 0.01, AUC = 0.67, 0.66, and 0.66). In addition, the risk scores were an independent risk factor for LUSC (HR = 2.34, 95%CI = 1.70–3.23). The practical nomogram was also built using the risk score, smoking status, and other clinical information with a good c-index (0.72, 95%CI = 0.70–0.74). Finally, we used other TCGA SCC cohorts to confirm the reliability and validity of the risk score model (p < 0.01 and AUC > 0.6 at 2, 3, and 5 years in CSCC and HNSC cohorts). In conclusion, the present study suggested that smoking cessation should be a part of smoking-related SCC treatment, and also provided a risk score model to predict prognosis and improve the effectiveness of screening the platinum/PARP population.

Plakophilin-2 Promotes Lung Adenocarcinoma Development via Enhancing Focal Adhesion and Epithelial-Mesenchymal Transition

Background

Lung cancer is one of the most aggressive tumors with high incidence and mortality, which could be classified into lung squamous cell carcinoma (LUSC) and lung adenocarcinoma (LUAD). Overexpression of Plakophilin-2 (PKP2) has been reported in multiple malignancies. However, the expression and function mechanism of PKP2 in LUAD remain illusive.

Methods

Real-time PCR (RT-PCR) was conducted to assess the expression of PKP2 in LUAD cells and tissues. An integrated analysis of PKP2 expression in The Cancer Genome Atlas (TCGA) was further performed. The effect of PKP2 on cell proliferation and invasion potential were then evaluated with loss-of-function assays in vitro. Xenograft nude mouse models were used to determine the role of PKP2 in LUAD tumorigenicity in vivo. Bioinformatics prediction, immunohistochemistry and Western blot were performed to examine whether PKP2 promoted LUAD development via enhancing focal adhesion and epithelial–mesenchymal transition.

Results

PKP2 expression was highly expressed in LUAD tissues compared with that in normal tissues and predicated poor prognosis of LUAD patients. TCGA LUAD cohort analysis also showed that high expression of PKP2 indicated unfavorable outcomes in LUAD patients. PKP2 expression was also upregulated in lung cancer cells. Functionally, knockdown of PKP2 suppressed lung cancer cell proliferation and invasion in vitro, while inhibited xenograft lung tumor development in vivo. Mechanistically, we demonstrated that high expression of PKP2 in LUAD was correlated with enhanced EMT and focal adhesion. Knockdown of PKP2 inhibited the expression of EMT-related Vimentin and N-cadherin and focal adhesion-associated expression of BMP4, ICAM1, and VCAM1 in xenograft tumors and lung cancer cells.

Conclusion

In summary, our findings indicate that PKP2 functions as an oncogene in LUAD, which could be utilized as a novel diagnostic and therapeutic marker for LUAD treatment.

Tobacco carcinogens and the methionine metabolism in human bladder cancer

Cigarette smoking is a strong risk factor for bladder cancer. It has been shown that the duration of smoking is associated with a poor prognosis and a higher risk of recurrence. This is due to tobacco carcinogens forming adducts with DNA and proteins that participate in the DNA repair mechanisms. Additionally, polymorphisms of genes responsible for methyl group transfer in the methionine cycle and dosages of vitamins (from diet and supplements) can cause an increased risk of bladder cancer. Upregulated DNA methyltransferase 1 expression and activity results in a high level of methylated products of metabolism, as well as hypermethylation of tumor suppressor genes. The development of a market that provides new inhibitors of DNA methyltransferase or alternatives for current smokers is essential not only for patients but also for people who are under the danger of secondhand smoking and can experience its long-term exposure consequences.

Mutational analysis of head and neck squamous cell carcinoma stratified by smoking status

Smoking has historically been recognized as a negative prognostic factor in head and neck squamous cell carcinoma (HNSCC). This study aimed to assess the mutational differences between heavy smokers (>20 pack years) and never smokers among the HNSCC patients within The Cancer Genome Atlas (TCGA). Single nucleotide variation and copy number aberration differences between heavy smokers and never smokers were compared within human papillomavirus-positive (HPV-positive) (n = 67) and HPV-negative (n = 431) TCGA cohorts with HNSCC, and the impact of these mutations on survival were assessed. No genes were differentially mutated between smoking and never-smoking patients with HPV-positive tumors. By contrast, in HPV-negative tumors, NSD1 and COL1A11 were found to be more frequently mutated in heavy smokers, while CASP8 was more frequently altered in never smokers. HPV-negative patients with NSD1 mutations experienced significantly improved overall survival compared with NSD1 WT patients. This improved prognosis was validated in an independent cohort of 77 oral cavity cancer patients and a meta-analysis that included 2 additional data sets (688 total patients, hazard ratio for death 0.44, 95% CI, 0.30-0.65). NSD1 mutations are more common in HPV-negative heavy smokers, define a cohort with favorable prognosis, and may represent a clinically useful biomarker to guide treatment deintensification for HPV-negative patients.

Differential Effect of Smoking on Gene Expression in Head and Neck Cancer Patients

Smoking is a well-known behavior that has an important negative impact on human health, and is considered to be a significant factor related to the development and progression of head and neck squamous cell carcinomas (HNSCCs). Use of high-dimensional datasets to discern novel HNSCC driver genes related to smoking represents an important challenge. The Cancer Genome Atlas (TCGA) analysis was performed in three co-existing groups of HNSCC in order to assess whether gene expression landscape is affected by tobacco smoking, having quit, or non-smoking status. We identified a set of differentially expressed genes that discriminate between smokers and non-smokers or based on human papilloma virus (HPV)16 status, or the co-occurrence of these two exposome components in HNSCC. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways classification shows that most of the genes are specific to cellular metabolism, emphasizing metabolic detoxification pathways, metabolism of chemical carcinogenesis, or drug metabolism. In the case of HPV16-positive patients it has been demonstrated that the altered genes are related to cellular adhesion and inflammation. The correlation between smoking and the survival rate was not statistically significant. This emphasizes the importance of the complex environmental exposure and genetic factors in order to establish prevention assays and personalized care system for HNSCC, with the potential for being extended to other cancer types.

Elucidating feed-forward apoptosis signatures in breast cancer datasets: Higher FOS expression associated with a better outcome

Overstimulation of pro-proliferative pathways and high level expression of pro-proliferative transcription factors (TFs) can lead to apoptosis. This is likely due to TF binding sites for pro-proliferative TFs common to pro-proliferative and pro-apoptosis-effector genes. Certain clinical datasets have indicated that molecular markers associated with higher proliferation rates lead to improved outcomes for patients with cancer. These observations have been extensively assessed on a general basis, however there has been little work dissecting feed-forward apoptosis signaling pathways that may represent specific distinctions between a pro-proliferative mechanism and a pro-apoptotic mechanism in samples from patients with cancer. Using The Cancer Genome Atlas datasets and bioinformatic approaches, the present study reports that higher FOS expression levels, along with higher FOS target apoptosis-effector gene expression, is associated with an increased survival, while higher POU2F1 expression is associated with a reduced survival (average difference of 25.9 months survival). In summary, in the datasets examined FOS represents an apoptosis-driver and high POU2F1 represents a driver mechanism for cancer development.

Smoking intensity and bladder cancer aggressiveness at diagnosis

OBJECTIVE

To explore the relation between cigarette smoking intensity and bladder cancer aggressiveness at first diagnosis.

METHODS

Patients diagnosed with urinary bladder cancer (BC) between 1995-2011 under the age of 75 years were retrospectively identified from the Netherlands Cancer Registry and invited for a study on genetic and lifestyle risk factors for BC. Information on patients' self-reported smoking history was retrieved by means of a postal questionnaire. Tumors were stratified regarding the risk of progression defined by tumor stage and grade. Multinomial logistic regression was used to analyze the relation between smoking intensity and aggressiveness of the tumor.

RESULTS

The UBC study population comprised 323 (17.4%) never smokers, 870 (46.8%) former cigarette smokers, and 630 (33.9%) current cigarette smokers. A higher smoking amount was a risk factor of getting high-risk non-muscle invasive bladder cancer (NMIBC) compared with low-risk NMIBC in ever and former cigarette smokers (OR: 1.02 per cigarette smoked, 95% CI: 1.00-1.03 and OR: 1.03, 95% CI: 1.01-1.05, respectively). A statistically significant dose-response increase in the risk of a more aggressive cancer type (high-risk NMIBC and MIBC) was observed with increasing smoking duration among former smokers (p for trend 0.035 and 0.008, respectively). No significant association of the evaluated smoking intensity variables was observed in current smokers. A longer time of smoking cessation correlated with a lower odds of a more aggressive cancer.

CONCLUSION

We observed a weak increase in the risk of a more aggressive tumor type with increasing smoking intensity in former smokers, but this association was absent in current smokers. This conflicting result may suggest that there is no strong relation between smoking intensity and bladder cancer aggressiveness. Analyses of prospective studies with longitudinal smoking assessment may provide a more definitive answer to the research question.

Smoking correlates with increased cytoskeletal protein-related coding region mutations in the lung and head and neck datasets of the cancer genome atlas

Cancer from smoking tobacco is considered dependent on mutagens, but significant molecular aspects of smoking‐specific, cancer development remain unknown. We defined sets of coding regions for oncoproteins, tumor suppressor proteins, and cytoskeletal‐related proteins that were compared between nonsmokers and smokers, for mutation occurrences, in the lung adenocarcinoma (LUAD), head and neck squamous carcinoma (HNSC), bladder carcinoma (BLCA), and pancreatic adenocarcinoma ( PAAD) datasets from the cancer genome atlas (TCGA). We uncovered significant differences in overall mutation rates, and in mutation rates in cytoskeletal protein‐related coding regions (CPCRs, including extracellular matrix protein coding regions), between nonsmokers and smokers in LUAD and HNSC (P < 0.001), raising the question of whether the CPCR mutation differences lead to different clinical courses for nonsmoker and smoker cancers. Another important question inspired by these results is, whether high smoker cancer mutation rates would facilitate genotoxicity or neoantigen‐based therapies. No significant, mutation‐based differences were found in the BLCA or PAAD datasets, between nonsmokers and smokers. However, a significant difference was uncovered for the average number of overall cancer mutations, in LUAD, for persons who stopped smoking more than 15 years ago, compared with more recent smokers (P < 0.032).