Xia Pu

Genetic Variants in MicroRNA Biosynthesis Pathways and Binding Sites Modify Ovarian Cancer Risk, Survival, and Treatment Response

MicroRNAs (miRNA) play important roles in tumorigenesis. Genetic variations in miRNA processing genes and miRNA binding sites may affect the biogenesis of miRNA and the regulatory effect of miRNAs to their target genes, hence promoting tumorigenesis. This study analyzed 226 single nucleotide polymorphisms (SNP) in miRNA processing genes and miRNA binding sites in 339 ovarian cancer cases and 349 healthy controls to assess association with cancer risk, overall survival, and treatment response. Thirteen polymorphisms were found to have significant association with risk. The most significant were 2 linked SNPs (r(2) = 0.99), rs2740351 and rs7813 in GEMIN4 [odds ratio (OR) = 0.71; 95% confidence interval (CI), 0.57-0.87 and OR = 0.71; 95% CI, 0.57-0.88, respectively]. Unfavorable genotype analysis showed the cumulative effect of these 13 SNPs on risk (P for trend < 0.0001). Potential higher order gene-gene interactions were identified, which categorized patients into different risk groups according to their genotypic signatures. In the clinical outcome study, 24 SNPs exhibited significant association with overall survival and 17 SNPs with treatment response. Notably, patients carrying a rare homozygous genotype of rs1425486 in PDGFC had poorer overall survival [hazard ratio (HR) = 2.69; 95% CI, 1.67-4.33] and worse treatment response (OR = 3.38; 95% CI, 1.39-8.19), compared to carriers of common homozygous and heterozygous genotypes. Unfavorable genotype analyses also showed a strong gene-dosage effect with decreased survival and increased risk of treatment nonresponse in patients with greater number of unfavorable genotypes (P for trend < 0.0001). Taken together, miRNA-related genetic polymorphisms may impact ovarian cancer predisposition and clinical outcome both individually and jointly.

A genome-wide association study of bladder cancer identifies a new susceptibility locus within SLC14A1, a urea transporter gene on chromosome 18q12.3

Genome-wide and candidate-gene association studies of bladder cancer have identified 10 susceptibility loci thus far. We conducted a meta-analysis of two previously published genome-wide scans (4501 cases and 6076 controls of European background) and followed up the most significant association signals [17 single nucleotide polymorphisms (SNPs) in 10 genomic regions] in 1382 cases and 2201 controls from four studies. A combined analysis adjusted for study center, age, sex, and smoking status identified a novel susceptibility locus that mapped to a region of 18q12.3, marked by rs7238033 (P = 8.7 × 10(-9); allelic odds ratio 1.20 with 95% CI: 1.13-1.28) and two highly correlated SNPs, rs10775480/rs10853535 (r(2)= 1.00; P = 8.9 × 10(-9); allelic odds ratio 1.16 with 95% CI: 1.10-1.22). The signal localizes to the solute carrier family 14 member 1 gene, SLC14A1, a urea transporter that regulates cellular osmotic pressure. In the kidney, SLC14A1 regulates urine volume and concentration whereas in erythrocytes it determines the Kidd blood groups. Our findings suggest that genetic variation in SLC14A1 could provide new etiological insights into bladder carcinogenesis.

Genome-wide association study identifies multiple loci associated with bladder cancer risk

Candidate gene and genome-wide association studies (GWAS) have identified 11 independent susceptibility loci associated with bladder cancer risk. To discover additional risk variants, we conducted a new GWAS of 2422 bladder cancer cases and 5751 controls, followed by a meta-analysis with two independently published bladder cancer GWAS, resulting in a combined analysis of 6911 cases and 11 814 controls of European descent. TaqMan genotyping of 13 promising single nucleotide polymorphisms with P < 1 × 10(-5) was pursued in a follow-up set of 801 cases and 1307 controls. Two new loci achieved genome-wide statistical significance: rs10936599 on 3q26.2 (P = 4.53 × 10(-9)) and rs907611 on 11p15.5 (P = 4.11 × 10(-8)). Two notable loci were also identified that approached genome-wide statistical significance: rs6104690 on 20p12.2 (P = 7.13 × 10(-7)) and rs4510656 on 6p22.3 (P = 6.98 × 10(-7)); these require further studies for confirmation. In conclusion, our study has identified new susceptibility alleles for bladder cancer risk that require fine-mapping and laboratory investigation, which could further understanding into the biological underpinnings of bladder carcinogenesis.

PI3K/PTEN/AKT/mTOR pathway genetic variation predicts toxicity and distant progression in lung cancer patients receiving platinum-based chemotherapy

Non-small cell lung cancer (NSCLC) is still the leading cause of cancer-related deaths. The effect of the PI3K/PTEN/AKT/mTOR signaling pathway on cancer treatment, including NSCLC, has been well documented. In this study, we analyzed associations between genetic variations within this pathway and clinical outcomes following platinum-based chemotherapy in 168 patients with stage IIIB (wet) or stage IV NSCLC. Sixteen tagging SNPs in five core genes (PIK3CA, PTEN, AKT1, AKT2, and FRAP1) of this pathway and identified SNPs associated with development of toxicity and disease progression. We observed significantly increased toxicity for patients with PIK3CA:rs2699887 (OR: 3.86, 95% CI: 1.08-13.82). In contrast, a SNP in PTEN was associated with significantly reduced risk for chemotherapeutic toxicity (OR: 0.44, 95% CI: 0.20-0.95). We identified three SNPs in AKT1 resulting in significantly decreased risks of distant progression in patients carrying at least one variant allele with HRs of 0.66 (95% CI: 0.45-0.97), 0.52 (95% CI: 0.35-0.77), and 0.62 (95% CI: 0.42-0.91) for rs3803304, rs2498804, and rs1130214, respectively. Furthermore, these same variants conferred nearly 2-fold increased progression-free survival times. The current study provides evidence that genetic variations within the PI3K/PTEN/AKT/mTOR signaling pathway are associated with variation in clinical outcomes of NSCLC patients. With further validation, our findings may provide additional biomarkers for customized treatment of platinum-based chemotherapy for NSCLC.

Genome-Wide Association Study of Genetic Predictors of Overall Survival for Non–Small Cell Lung Cancer in Never Smokers

To identify the genetic factors that influence overall survival in never smokers who have non-small cell lung carcinoma (NSCLC), we conducted a consistency meta-analysis study using genome-wide association approaches for overall survival in 327 never smoker patients with NSCLC from The University of Texas MD Anderson Cancer Center (Houston, TX) and 293 cases from the Mayo Clinic (Rochester, MN). We then conducted a two-pronged validation of the top 25 variants that included additional validation in 1,256 patients with NSCLC from Taiwan and assessment of expression quantitative trait loci (eQTL) and differential expression of genes surrounding the top loci in 70 tumors and matched normal tissues. A total of 94 loci were significant for overall survival in both MD Anderson and Mayo studies in the consistency meta-analysis phase, with the top 25 variants reaching a P value of 10(-6). Two variants of these 25 were also significant in the Taiwanese population: rs6901416 [HR, 1.44; 95% confidence interval (CI), 1.01-2.06] and rs10766739 (HR, 1.23; 95%CI, 1.00-1.51). These loci resulted in a reduction of median survival time of at least eight and five months in three populations, respectively. An additional six variants (rs4237904, rs7976914, rs4970833, rs954785, rs485411, and rs10906104) were validated through eQTL analysis that identified significant correlations with expression levels of six genes (LEMD3, TMBIM, ATXN7L2, SHE, ITIH2, and NUDT5, respectively) in normal lung tissue. These genes were also significantly differentially expressed between the tumor and normal lung tissue. These findings identify several novel, candidate prognostic markers for NSCLC in never smokers, with eQTL analysis suggesting a potential biologic mechanism for a subset of these observed associations.

Variants in inflammation genes are implicated in risk of lung cancer in never smokers exposed to second-hand smoke

Lung cancer in lifetime never smokers is distinct from that in smokers, but the role of separate or overlapping carcinogenic pathways has not been explored. We therefore evaluated a comprehensive panel of 11,737 single-nucleotide polymorphisms (SNP) in inflammatory-pathway genes in a discovery phase (451 lung cancer cases, 508 controls from Texas). SNPs that were significant were evaluated in a second external population (303 cases, 311 controls from the Mayo Clinic). An intronic SNP in the ACVR1B gene, rs12809597, was replicated with significance and restricted to those reporting adult exposure to environmental tobacco smoke. Another promising candidate was an SNP in NR4A1, although the replication OR did not achieve statistical significance. ACVR1B belongs to the TGFR-β superfamily, contributing to resolution of inflammation and initiation of airway remodeling. An inflammatory microenvironment (second-hand smoking, asthma, or hay fever) is necessary for risk from these gene variants to be expressed. These findings require further replication, followed by targeted resequencing, and functional validation.

Cyclooxygenase-2 gene polymorphisms reduce the risk of oral premalignant lesions

Oral premalignant lesions (OPLs) have the potential to transform into malignant oral cancers. Overexpression of the cyclooxygenase‐2 gene (COX‐2) is observed frequently in OPLs and oral cancers, suggesting that this gene may play an important role in the progression of oral cancer. Single‐nucleotide polymorphisms of COX‐2 have been associated with the risk of multiple cancers; however, to date, their effects on OPL susceptibility have not been evaluated sufficiently.

The ability of bilirubin in identifying smokers with higher risk of lung cancer: a large cohort study in conjunction with global metabolomic profiling

Purpose: We aimed to identify serum metabolites as potential valuable biomarkers for lung cancer and to improve risk stratification in smokers. Experimental Design: We performed global metabolomic profiling followed by targeted validation of individual metabolites in a case–control design of 386 lung cancer cases and 193 matched controls. We then validated bilirubin, which consistently showed significant differential levels in cases and controls, as a risk marker for lung cancer incidence and mortality in a large prospective cohort composed of 425,660 participants. Results: Through global metabolomic profiling and following targeted validation, bilirubin levels consistently showed a statistically significant difference among healthy controls and lung cancer cases. In the prospective cohort, the inverse association was only seen in male smokers, regardless of smoking pack-years and intensity. Compared with male smokers in the highest bilirubin group (>1 mg/dL), those in the lowest bilirubin group (<0.75 mg/dL) had 55% and 66% increase in risks of lung cancer incidence and mortality, respectively. For every 0.1 mg/dL decrease of bilirubin, the risks for lung cancer incidence and mortality increased by 5% and 6% in male smokers, respectively (both P < 0.001). There was a significant interaction between low serum bilirubin level and smoking on lung cancer risk (Pinteraction = 0.001). Conclusion: Low levels of serum bilirubin are associated with higher risks of lung cancer incidence and mortality in male smokers and can be used to identify higher risk smokers for lung cancer. Clin Cancer Res; 21(1); 193–200. ©2014 AACR.

Role of Inflammatory Related Gene Expression in Clear Cell Renal Cell Carcinoma Development and Clinical Outcomes

PURPOSE Renal cell carcinoma is the eighth most common cancer in the United States and clear cell renal carcinoma is the most common type. Many signaling pathways are implicated in clear cell renal carcinoma development, including the inflammation pathway. However, less is known about how gene expression variation in this pathway influences clear cell renal carcinoma development and clinical outcomes. MATERIALS AND METHODS Gene expression in tumor and adjacent normal tissues from 93 patients was detected using a genome-wide expression array. A panel of 661 inflammation related genes was then analyzed. Differential expression patterns between tumor and normal tissues were identified. Association with recurrence or survival was evaluated with genes showing significant association tested further in a validation set of 258 tumors using an independent platform (quantitative real-time polymerase chain reaction). RESULTS We identified 151 genes with at least a two-fold change in gene expression between adjacent normal tissue and tumor, of which most were up-regulated in tumors. A total of 20 genes significantly associated with recurrence and/or overall survival were selected for further validation. In the replication data set high expression of GADD45G was significantly associated with a 2.09-fold (95% CI 1.08-6.14, p = 0.034) increased risk of recurrence while high CARD9, NCF2 and CIITA expression was significantly associated with a 2.52-fold (95% CI 1.24-5.12, p = 0.010), 2.26-fold (95% CI 1.12-4.58, p = 0.023) and 2.11-fold (95% CI 1.05-4.27, p = 0.037) increased risk of death, respectively. CONCLUSIONS Results suggest that inflammation gene expression may be significant prognostic biomarkers for the risk of recurrence (GADD45G) and death (CARD9, CIITA and NCF2) in patients with clear cell renal carcinoma.

Cigarette Experimentation in Mexican Origin Youth: Psychosocial and Genetic Determinants

Background: Established psychosocial risk factors increase the risk for experimentation among Mexican origin youth. Now, we comprehensively investigate the added contribution of select polymorphisms in candidate genetic pathways associated with sensation seeking, risk taking, and smoking phenotypes to predict experimentation. Methods: Participants (N = 1,118 Mexican origin youth) recruited from a large population-based cohort study in Houston, TX, provided prospective data on cigarette experimentation over 3 years. Psychosocial data were elicited twice—baseline and final follow-up. Participants were genotyped for 672 functional and tagging variants in the dopamine, serotonin, and opioid pathways. Results: After adjusting for gender and age, with a Bayesian False Discovery Probability set at 0.8 and prior probability of 0.05, six gene variants were significantly associated with risk of experimentation. After controlling for established risk factors, multivariable analyses revealed that participants with six or more risk alleles were 2.25 [95% confidence interval (CI), 1.62–3.13] times more likely to have experimented since baseline than participants with five or fewer. Among committed never-smokers (N = 872), three genes (OPRM1, SNAP25, HTR1B) were associated with experimentation as were all psychosocial factors. Among susceptible youth (N = 246), older age at baseline, living with a smoker, and three different genes (HTR2A, DRD2, SLC6A3) predicted experimentation. Conclusions: Our findings, which have implications for development of culturally specific interventions, need to be validated in other ethnic groups. Impact: These results suggest that variations in select genes interact with a cognitive predisposition toward smoking. In susceptible adolescents, the impact of the genetic variants appears to be larger than committed never-smokers. Cancer Epidemiol Biomarkers Prev; 21(1); 228–38. ©2011 AACR.