Yuan Hung Wang

Arsenic in Drinking Water and Risk of Urinary Tract Cancer: A Follow-up Study from Northeastern Taiwan

The evidence linking arsenic in drinking water with increased urinary cancer risk comes from populations in relatively high exposure areas (>100 μg/L), whereas studies from lower exposure areas (<100 μg/L) reported inconsistent results. A previous study conducted in northeastern Taiwan, where residents were exposed to relatively lower concentrations, reported increased risk of urinary cancer in a dose-response way. Using the same cohort with longer follow-up, we conducted analysis to elucidate the relationship between ingested arsenic and urinary cancer in lower exposure groups and assessed the influence of duration, recency, and latency of drinking arsenic-containing well water. A total of 8,086 residents from northeastern Taiwan were followed for 12 years. Incident urinary cancer was ascertained through linkage with the national cancer registry. All analysis was done by Cox proportional hazards regression models. There were 45 incidences of urinary cancer and a monotonic increased risk of urinary cancer was found with increasing arsenic concentration (P < 0.001). For the highly exposed (>100 μg/L), the relative risks (RR) were >5-fold, whereas the risk was elevated but not significant for low exposure (<100 μg/L). Relative to the arsenic concentration <10 μg/L, those who drank well water with higher concentration from birth [RR, 3.69; 95% confidence interval (95% CI), 1.31-10.4], still drank at enrollment (RR, 3.50; 95% CI, 1.33-9.22), and drank for >50 years (RR, 4.12; 95% CI, 1.48-11.5) had a significantly increased risk of urinary cancer. When restricted to urothelial carcinoma, all risk estimates including concentration and characteristics of well water consumption were higher. Cancer Epidemiol Biomarkers Prev; 19(1); 101–10

The emerging role of SOX2 in cell proliferation and survival and its crosstalk with oncogenic signaling in lung cancer

Tumor cells have long been observed to share several biological characteristics with normal stem/progenitor cells; however, the oncogenic mechanisms underlying the lung stem/progenitor cell signaling remain elusive. Here, we report that SOX2, a self‐renewal factor in lung stem/progenitor cells, is highly expressed in a subclass of lung cancer cells, the proliferation, survival, and chemoresistance of which are dependent on SOX2 signaling. Overexpression of SOX2 promotes oncogenic phenotypes in lung cancer cells; knockdown of SOX2 attenuated cell proliferation. We observed that SOX2 increased the expression of epidermal growth factor receptor (EGFR), and EGFR activation further upregulated SOX2 levels, forming a positive feedback loop. SOX2 expression promoted chemoresistance, and silencing of SOX2 perturbed mitochondrial function, causing marked apoptosis and autophagy. SOX2 induced BCL2L1, the ectopic expression of which rescued the effects of SOX2 silencing on apoptosis, autophagy, and mitochondrial function. SOX2 promoted tumor formation, along with increased cell proliferation in a xenograft mouse model. SOX2 expression is associated with poor prognosis in lung cancer patients; moreover, SOX2, EGFR, and BCL2L1 expression levels were significantly correlated in lung tumors. Our findings support the emerging role of SOX2 in cell proliferation and survival by eliciting oncogenic EGFR and BCL2L1 signaling with potential applications as a prognosis marker and a therapeutic target in lung cancer. Stem Cells 2013;31:2607–2619

Association Between Survivin Gene Promoter -31 C/G Polymorphism and Urothelial Carcinoma Risk in Taiwanese Population

OBJECTIVES To investigate the association between survivin gene promoter -31 C/G polymorphism and urothelial carcinoma (UC) risk in a Taiwanese population. METHODS A total of 190 patients with pathologically confirmed UC and 210 unrelated controls without cancer were recruited at Chiayi Christian Hospital from August 2002 to May 2007. The -31 C/G polymorphism in the survivin gene promoter was determined using polymerase chain reaction-restriction fragment length polymorphism analysis. RESULTS Compared with study subjects carrying the G/G genotype, significantly increased UC risks were found for individuals carrying the C/G genotype (odds ratio 2.8; 95% confidence interval [CI] 1.7-4.6) and those with the C/C genotype (odds ratio 4.0; 95% CI 2.3-7.2). Those carrying the C/C or C/G genotype had a significantly increased UC risk of 3.2 (95% CI 1.9-5.2) compared with those with the G/G genotype. Among heavy smokers (> or = 30 pack-years), we found a significantly increased UC risk of 3.8 (95% CI 1.3-11.3) for individuals with the C/C or C/G genotype compared with those with the G/G genotype. Furthermore, patients with UC carrying the C/C genotype had a significantly greater prevalence of muscle-invasive (Stage T2-T4), high-grade (G3), or invasive, high-grade tumor compared with those carrying the G/G genotype. CONCLUSIONS These findings suggest that the -31 C/G polymorphism of the survivin gene promoter is associated with both the clinical tumor stage and the pathologic tumor grade and might be involved in the development of UC.

A significantly joint effect between arsenic and occupational exposures and risk genotypes/diplotypes of CYP2E1, GSTO1 and GSTO2 on risk of urothelial carcinoma.

Cigarette smoking, arsenic and occupational exposures are well-known risk factors for the development of urothelial carcinoma (UC). Therefore, the aim of this study is to investigate whether the effect of cigarette smoking, alcohol consumption, arsenic and occupational exposures on risk of UC could be modified by genetic polymorphisms of cytochrome P450 2E1 and glutathione S-transferase omega. A hospital-based case-control study consisted of 520 histologically confirmed UC cases, and 520 age- and gender-matched cancer-free controls were carried out from September 1998 to December 2007. Genotyping of CYP2E1, GSTO1 and GSTO2 was determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Subjects with both of cigarette smoking and alcohol consumption have a significantly increased UC risk (odds ratio [OR]=2.9; 95% confidence interval [CI]=1.9-4.4). Significantly increased UC risks of 1.5 and 1.9 were found for study subjects with high arsenic exposure and those who have been exposed to two or more occupational exposures, respectively. A significantly increased UC risk of 3.9 was observed in study subjects with H2-H2 diplotype of GSTO1 and GSTO2. The significantly highest UC risk of 9.0 was found for those with all environmental risk factors of cigarette smoking, alcohol consumption, arsenic and occupational exposures and two or more risk genotypes/diplotypes of CYP2E1, GSTO1 and GSTO2. Our findings suggest that a significantly joint effect of cigarette smoking, alcohol consumption, arsenic and occupational exposures and risk genotypes/diplotypes of CYP2E1, GSTO1 and GSTO2 on risk of UC was found.

Use of arsenic-induced palmoplantar hyperkeratosis and skin cancers to predict risk of subsequent internal malignancy

Hyperpigmentation, hyperkeratoses, and Bowens disease are hallmarks of chronic arsenic exposure. The association between arsenic-induced skin lesions and subsequent internal cancers is examined by using a community-based prospective study. The cohort was enrolled from an arseniasis-endemic area in southwestern Taiwan, where 2,447 residents participated in skin examinations during the late 1980s. The number of participants diagnosed with hyperpigmentation was 673; with hyperkeratosis, 243; and with skin cancer (Bowens disease or non-melanoma skin cancer), 378. Newly diagnosed internal cancers were ascertained through linkage with National Cancer Registry profiles. Cox regression was performed to estimate hazard ratios with 95% confidence intervals for potential risk predictors. Compared with participants without skin lesions, patients affected with skin cancers had a significantly increased risk of lung cancer (hazard ratio = 4.64, 95% confidence interval: 2.92, 7.38) and urothelial carcinoma (hazard ratio = 2.02, 95% confidence interval: 1.23, 3.30) after adjustment for potential confounders and cumulative arsenic exposure. Hyperkeratosis is significantly associated with an increased lung cancer risk (hazard ratio = 2.76, 95% confidence interval: 1.35, 5.67). A significant interactive effect on lung cancer risk between hyperkeratosis and cigarette smoking was identified, which suggests that patients with hyperkeratosis who have been exposed to arsenic should cease smoking.

CITED2 functions as a molecular switch of cytokine-induced proliferation and quiescence.

Transforming growth factor-α (TGF-α)-induced proliferation and transforming growth factor-β (TGF-β)-mediated quiescence are intricately balanced in normal lung-tissue homeostasis but are deregulated during neoplastic progression of lung cancer. Here, we show that Cbp/p300-interacting transactivator with Glu/Asp-rich carboxy-terminal domain 2 (CITED2), a novel MYC-interacting transcriptional modulator, responds to TGF-α induction and TGF-β suppression to orchestrate cellular proliferation and quiescence, respectively. Upon TGF-α induction, CITED2 was induced by MYC and further modulated MYC-mediated transcription in a feed-forward manner. CITED2 recruited p300 to promote MYC-p300-mediated transactivation of E2F3, leading to increased G1/S cell cycle progression. Moreover, CITED2 inhibited cellular quiescence by enhancing MYC-mediated suppression of p21CIP1. CITED2 interacted with histone deacetylase 1 (HDAC1) and potentiated MYC–HDAC1 complex formation. TGF-β stimulation provoked downregulation of CITED2, which abrogated MYC-HDAC1-mediated p21CIP1 suppression, causing cellular quiescence. Ectopic CITED2 expression enhanced tumor growth in nude mice; furthermore, CITED2 knockdown caused tumor shrinkage and increased overall host mouse survival rates. Expression of CITED2/MYC/E2F3/p21CIP1 signaling molecules was associated with poor prognosis of lung cancer patients. Thus, CITED2 functions as a molecular switch of TGF-α and TGF-β-induced growth control, and MYC-CITED2 signaling axis provides a new index for predicting clinical outcome.

Comparing the joint effect of arsenic exposure, cigarette smoking and risk genotypes of vascular endothelial growth factor on upper urinary tract urothelial carcinoma and bladder cancer

Arsenic exposure and cigarette smoking are environmental risk factors for urothelial carcinoma (UC). Vascular endothelial growth factor (VEGF) is the key regulator of angiogenesis in various malignancies. This study investigates the joint effect of arsenic exposure, cigarette smoking, and VEGF polymorphisms on UC risk. This was a hospital-based case-control study consisting of 730 histopathologically confirmed UC cases, including 470 bladder cancers, 260 upper urinary tract UCs (UUTUCs), and 850 age-matched controls, recruited from September 1998 to December 2009. UC risk was estimated by odds ratios and 95% confidence intervals using unconditional logistic regression. Ever smokers with high arsenic exposure had significantly increased risks of 5.7 and 6.4 for bladder cancer and UUTUC, respectively. Moreover, ever smokers with high arsenic exposure carrying 1 or 2 risk genotypes of the VEGF gene had a significantly increased risk of 6.6 for bladder cancer and a strikingly higher risk of 9.9 for UUTUC. Additionally, UUTUC cases with high arsenic exposure carrying 1 or 2 risk genotypes of the VEGF gene had a non-significant increased risk of advanced tumor stage. Our findings suggest that arsenic exposure, cigarette smoking, and risk genotypes of VEGF contribute to a higher risk of UUTUC than of bladder cancer.

GT-repeat polymorphism in the heme oxygenase-1 gene promoter is associated with cardiovascular mortality risk in an arsenic-exposed population in northeastern Taiwan.

Inorganic arsenic has been associated with increased risk of atherosclerotic vascular disease and mortality in humans. A functional GT-repeat polymorphism in the heme oxygenase-1 (HO-1) gene promoter is inversely correlated with the development of coronary artery disease and restenosis after clinical angioplasty. The relationship of HO-1 genotype with arsenic-associated cardiovascular disease has not been studied. In this study, we evaluated the relationship between the HO-1 GT-repeat polymorphism and cardiovascular mortality in an arsenic-exposed population. A total of 504 study participants were followed up for a median of 10.7 years for occurrence of cardiovascular deaths (coronary heart disease, cerebrovascular disease, and peripheral arterial disease). Cardiovascular risk factors and DNA samples for determination of HO-1 GT repeats were obtained at recruitment. GT repeats variants were grouped into the S (<27 repeats) or L allele (≥ 27 repeats). Relative mortality risk was estimated using Cox regression analysis, adjusted for competing risk of cancer and other causes. For the L/L, L/S, and S/S genotype groups, the crude mortalities for cardiovascular disease were 8.42, 3.10, and 2.85 cases/1000 person-years, respectively. After adjusting for conventional cardiovascular risk factors and competing risk of cancer and other causes, carriers with class S allele (L/S or S/S genotypes) had a significantly reduced risk of cardiovascular mortality compared to non-carriers (L/L genotype) [OR, 0.38; 95% CI, 0.16-0.90]. In contrast, no significant association was observed between HO-1 genotype and cancer mortality or mortality from other causes. Shorter (GT)n repeats in the HO-1 gene promoter may confer protective effects against cardiovascular mortality related to arsenic exposure.

Association of heme oxygenase-1 GT-repeat polymorphism with blood pressure phenotypes and its relevance to future cardiovascular mortality risk: An observation based on arsenic-exposed individuals

OBJECTIVE Heme oxygenase (HO)-1 is up-regulated as a cellular defense responding to stressful stimuli in experimental studies. A GT-repeat length polymorphism in the HO-1 gene promoter was inversely correlated to HO-1 induction. Here, we reported the association of GT-repeat polymorphism with blood pressure (BP) phenotypes, and their interaction on cardiovascular (CV) mortality risk in arsenic-exposed cohorts. METHODS Associations of GT-repeat polymorphism with BP phenotypes were investigated at baseline in a cross-sectional design. Effect of GT-repeat polymorphism on CV mortality was investigated in a longitudinal design stratified by hypertension. GT-repeat variants were grouped by S (<27 repeats) or L (≥ 27 repeats) alleles. Multivariate analyses were used to estimate the effect size after accounting for CV covariates. RESULTS Totally, 894 participants were recruited and analyzed. At baseline, carriers with HO-1 S alleles had lower diastolic BP (L/S genotypes, P = 0.014) and a lower possibility of being hypertensive (L/S genotypes, P = 0.048). After follow-up, HO-1 S allele was significantly associated with a reduced CV risk in hypertensive participants [relative mortality ratio (RMR) 0.27 (CI 0.11, 0.69), P = 0.007] but not in normotensive. Hypertensive participants without carrying the S allele had a 5.23-fold increased risk [RMR 5.23 (CI 1.99, 13.69), P = 0.0008] of CV mortality compared with normotensive carrying the S alleles. CONCLUSIONS HO-1 short GT-repeat polymorphism may play a protective role in BP regulation and CV mortality risk in hypertensive individuals against environmental stressors.

Comparison of Genome-wide DNA Methylation in Urothelial Carcinomas of Patients with and without Arsenic Exposure

BACKGROUND Arsenic is a well-documented carcinogen of human urothelial carcinoma (UC) with incompletely understood mechanisms. OBJECTIVES This study aimed to compare the genome-wide DNA methylation profiles of arsenic-induced UC (AsUC) and non-arsenic-induced UC (Non-AsUC), and to assess associations between site-specific methylation levels and cumulative arsenic exposure. METHODS Genome-wide DNA methylation profiles in 14 AsUC and 14 non-AsUC were analyzed by Illumina Infinium methylation27 BeadChip and validated by bisulfite pyrosequencing. Mean methylation levels (β¯) in AsUC and non-AsUC were compared by their ratio (β¯ ratio) and difference (Δβ¯). Associations between site-specific methylation levels in UC and cumulative arsenic exposure were examined. RESULTS Among 27,578 methylation sites analyzed, 231 sites had β¯ ratio >2 or <0.5 and 45 sites had Δβ¯ >0.2 or <-0.2. There were 13 sites showing statistically significant (q<0.05) differences in β¯ between AsUC and non-AsUC including 12 hypermethylation sites in AsUC and only one hypermethylation site in non-AsUC. Significant associations between cumulative arsenic exposure and DNA methylation levels of 28 patients were observed in nine CpG sites of nine gens including PDGFD (Spearman rank correlation, 0.54), CTNNA2 (0.48), KCNK17 (0.52), PCDHB2 (0.57), ZNF132 (0.48), DCDC2 (0.48), KLK7 (0.48), FBXO39 (0.49), and NPY2R (0.45). These associations remained statistically significant for CpG sites in CTNNA2, KLK7, NPY2R, ZNF132 and KCNK17 in 20 non-smoking women after adjustment for tumor stage and age. CONCLUSIONS Significant associations between cumulative arsenic exposure and methylation level of CTNNA2, KLK7, NPY2R, ZNF132 and KCNK17 were found in smoking-unrelated urothelial carcinoma. Arsenic exposure may cause urothelial carcinomas through the hypermethylation of genes involved in cell adhesion, proteolysis, transcriptional regulation, neuronal pathway, and ion transport. The findings of this study, which are limited by its small sample size and moderate dose-response relation, remain to be validated by further studies with large sample sizes.