Metformin inhibits pancreatic cancer metastasis caused by SMAD4 deficiency and consequent HNF4G upregulation

Pancreatic ductal adenocarcinoma (PDAC) has poor prognosis due to limited therapeutic options. This study examines the roles of genome-wide association study identified PDAC-associated genes as therapeutic targets. We have identified HNF4G gene whose silencing most effectively repressed PDAC cell invasiveness. HNF4G overexpression is induced by the deficiency of transcriptional factor and tumor suppressor SMAD4. Increased HNF4G are correlated with SMAD4 deficiency in PDAC tumor samples and associated with metastasis and poor survival time in xenograft animal model and in patients with PDAC (log-rank P = 0.036; HR = 1.60, 95% CI = 1.03-2.47). We have found that Metformin suppresses HNF4G activity via AMPK-mediated phosphorylation-coupled ubiquitination degradation and inhibits in vitro invasion and in vivo metastasis of PDAC cells with SMAD4 deficiency. Furthermore, Metformin treatment significantly improve clinical outcomes and survival in patients with SMAD4-deficient PDAC (log-rank P = 0.022; HR = 0.31, 95% CI = 0.14-0.68) but not in patients with SMAD4-normal PDAC. Pathway analysis shows that HNF4G may act in PDAC through the cell-cell junction pathway. These results indicate that SMAD4 deficiency-induced overexpression of HNF4G plays a critical oncogenic role in PDAC progression and metastasis but may form a druggable target for Metformin treatment.

Genetic variation in DNA polymerase kappa gene is associated with the prognosis after platinum-based chemotherapy in small cell lung cancer patients / 中华肿瘤杂志

Objective@#To investigate the associations between genetic variations of DNA polymerase kappa (POLK) and treatment response to platinum-based chemotherapy of small cell lung cancer (SCLC), and to analyze the influencing factors on survival.@*Methods@#Five haplotype-tagging single nucleotide polymorphisms (htSNPs) of POLK were genotyped by Sequenom MassARRAY methods in 1 030 SCLC patients who received platinum-based chemotherapy, and had different response and survival time. The associations between SNPs and treatment response were analyzed by computing the odds ratios (ORs) and 95% confidence intervals (CIs) from logistic regression model. Cox regression was used for survival analysis between SNPs and overall survival by computing the hazard ratios (HRs) and 95% CIs.@*Results@#Among 1 030 cases, 558 (54.2%) cases received cis-platinum and etoposide treatment while others treated with carboplatin and etoposide. Seven hundred and eighty eight patients were chemotherapy responders in the study with a response rate of 76.5%. The median follow-up time of these patients was 22.0 months. Patients were followed up to get their survival information. The median survival time of these patients was 22.5 months. Six hundred and seventy three patients (65.3%) had died by the last date of follow-up to get their survival information (Dec 21, 2017). Five htSNPs of POLK were not associated with the chemotherapy response of SCLC patients who received platinum-based chemotherapy (all P>0.05). Multivariate Cox proportional hazards regression model analysis showed that, rs73120833 of POLK was significantly associated with the overall survival (OS) of SCLC patients, compared with POLK rs73120833 T allele, C allele can prolong OS (adjusted HR=0.87, 95% CI=0.77-0.97, P=0.021). The remaining 4 SNPS, including rs10077427, rs3756558, rs4549504 and rs5744545, were not significantly associated with overall survival. Age≤56, KPS> 80, limited-stage, chemotherapy response and radiation therapy can remarkably prolong OS (all P<0.05).@*Conclusion@#These results suggest that POLK genetic polymorphism rs73120833 plays an important role on the prognosis of SCLC patients, which can be potential genetic biomarker for SCLC personalized treatment.

Associations of Genetic Variations in Mismatch Repair Genes MSH3 and PMS1 with Acute Adverse Events and Survival in Patients with Rectal Cancer Receiving Postoperative Chemoradiotherapy / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Mismatch repair (MMR) deficiency plays a critical role in rectal cancer. This study aimed to explore the associations between genetic variations in seven MMR genes and adverse events (AEs) and survival of patients with rectal cancer treated with postoperative chemoradiotherapy (CRT). MATERIALS AND METHODS: Fifty single nucleotide polymorphisms in seven MMR (MLH1, MLH3, MSH2, MSH3, MSH6, PMS1 and PMS2) genes were genotyped by Sequenom MassARRAY method in 365 patients with locally advanced rectal cancer receiving postoperative CRT. The associations between genotypes and AEs were measured by odds ratios and 95% confidence intervals (CIs) by unconditional logistic regression model. The associations between genetic variations and survival were computed by the hazard ratios and 95% CIs by Cox proportional regression model. RESULTS: The most common grade ≥ 2 AEs in those 365 patients, in decreasing order, were diarrhea (44.1%), leukopenia (29.6%), and dermatitis (18.9%). Except 38 cases missing, 61 patients (18.7%) died during the follow-up period. We found MSH3 rs12513549, rs33013 and rs6151627 significantly associated with the risk of grade ≥ 2 diarrhea. PMS1 rs1233255 had an impact on the occurrence of grade ≥2 dermatitis. Meanwhile, PMS1 rs4920657, rs5743030, and rs5743100 were associated with overall survival (OS) time of rectal cancer. CONCLUSION: These results suggest that MSH3 and PMS1 polymorphisms may play important roles in AEs prediction and prognosis of rectal cancer patients receiving postoperative CRT, which can be potential genetic biomarkers for rectal cancer personalized treatment.

Genetic variations in MLH3 and MSH2 genes are associated with the sensitivity and prognosis in locally advanced rectal cancer patients receiving preoperative chemoradiotherapy / 中华肿瘤杂志

Objective@#To investigate the associations between genetic variations in DNA mismatch repair genes and sensitivity as well as prognosis to preoperative chemoradiotherapy in patients with locally advanced rectal cancer.@*Methods@#Fourteen haplotype-tagging single nucleotide polymorphisms (htSNPs) of MLH1, MLH3 and MSH2 genes were genotyped by Sequenom MassARRAY method in 146 patients with locally advanced rectal cancer who received preoperative chemoradiotherapy. The associations between genotypes and response to capecitabine-based neoadjuvant chemoradiotherapy (nCRT) were measured by odds ratios (ORs) and 95% confidence intervals (CIs), adjusted for sex, age, clinical stages and karnofsky performance score (KPS) by unconditional logistic regression model. The survival analyses were performed by the hazard ratios (HRs) and 95% CIs by Cox proportional regression model.@*Results@#Among 146 cases, 64 patients were nCRT responders with a response rate of 43.8%. MLH3 rs175057 C>T and MSH2 rs13019654 G>T loci were associated with the sensitivity to preoperative chemoradiotherapy. Compared with the rs175057 CC genotype, the adjusted OR for patients with CT and TT genotypes was 0.42 (95% CI: 0.19-0.91; P=0.029). Moreover, for rs13019654, the adjusted OR for patients with the GT or TT genotypes was 0.49 (95% CI: 0.24-0.98; P=0.047) than those with GG genotype. The remaining 12 SNPs, including rs1540354, rs4026175, rs1981929, rs2042649, rs2303428, rs3771273, rs4608577, rs4952887, rs6544991, rs6544997, rs10188090 and rs10191478, were not significantly associated with therapeutic response to preoperative chemoradiotherapy. Meanwhile, MLH3 rs175057 C>T locus was also associated with longer overall survival time in locally advanced rectal cancer (HR=0.44, 95% CI: 0.20-0.96, P=0.038), whereas MSH2 rs3771273 T>A, rs10188090 A>G and rs10191478 T>G loci were associated with shorter overall survival time (HR=1.74, 95% CI: 1.06-2.84, P=0.028; HR=1.64, 95% CI: 1.01-2.66, P=0.046; HR=1.71, 95% CI: 1.01-2.91, P=0.047, respectively). The remaining 10 SNPs, including rs1540354, rs4026175, rs1981929, rs2042649, rs2303428, rs4608577, rs4952887, rs6544991, rs6544997 and rs13019654, were not significantly associated with prognosis.@*Conclusions@#Genetic polymorphisms of MLH3 rs175057 and MSH2 rs13019654 loci can predict the nCRT response, while MLH3 rs175057 as well as MSH2 rs3771273, rs10188090 and rs10191478 may predict prognosis in patients with locally advanced rectal cancer who received preoperative chemoradiotherapy. Therefore, these SNPs could be used as potential genetic markers in the personalized therapy of rectal cancer.

CCGD-ESCC: A Comprehensive Database for Genetic Variants Associated with Esophageal Squamous Cell Carcinoma in Chinese Population / 基因组蛋白质组与生物信息学报·英文版

Esophageal squamous-cell carcinoma (ESCC) is one of the most lethal malignancies in the world and occurs at particularly higher frequency in China. While several genome-wide association studies (GWAS) of germline variants and whole-genome or whole-exome sequencing studies of somatic mutations in ESCC have been published, there is no comprehensive database publically available for this cancer. Here, we developed the Chinese Cancer Genomic Database-Esophageal Squamous Cell Carcinoma (CCGD-ESCC) database, which contains the associations of 69,593 single nucleotide polymorphisms (SNPs) with ESCC risk in 2022 cases and 2039 controls, survival time of 1006 ESCC patients (survival GWAS) and gene expression (expression quantitative trait loci, eQTL) in 94 ESCC patients. Moreover, this database also provides the associations between 8833 somatic mutations and survival time in 675 ESCC patients. Our user-friendly database is a resource useful for biologists and oncologists not only in identifying the associations of genetic variants or somatic mutations with the development and progression of ESCC but also in studying the underlying mechanisms for tumorigenesis of the cancer. CCGD-ESCC is freely accessible at http://db.cbi.pku.edu.cn/ccgd/ESCCdb.

Correlations between genetic variations of glutathione synthetase gene and the response to platinum-based chemotherapy and prognosis of small cell lung cancer patients / 中华肿瘤杂志

Objective@#To explore the associations between genetic variations of glutathione synthetase gene (GSS) and response to platinum-based chemotherapy of small cell lung cancer(SCLC), and to analyze the influencing factors on survival.@*Methods@#Four haplotype-tagging single nucleotide polymorphisms (htSNPs) of GSS were genotyped by Sequenom MassARRAY methods in 903 SCLC patients who received platinum-based chemotherapy, and had different response and survival time. The associations between genotypes and platinum-based chemotherapy response were measured by odds ratios (OR) and 95% confidence intervals (CI), adjusted for sex, age, smoking, KPS, staging and chemotherapy regiments, by unconditional logistic regression model. The hazard ratios (HR) were estimated by Cox proportional hazards regression model.@*Results@#Among the 903 patients, 462(51.2%) cases received cis-platinum and etoposide treatment while others were treated with carboplatin and etoposide. 656 patients were chemotherapy responders in the study with a response rate of 72.6%. Patients were followed up to get their survival information. The median survival time (MST) of these patients was 25.0 months.We found that rs725521 located in the 3′ near gene region of GSS was significantly associated with chemotherapy response. Compared with the T allele, patients with C allele had a worse chemotherapy response and an increased risk of no-responders (P=0.027). Rs7265992 and rs725521 of GSS were associated with the overall survival (OS) of SCLC patients who received platinum-based chemotherapy (HR=1.16, 95% CI=1.02-1.33, P=0.027; HR=1.17, 95% CI=1.05-1.31, P=0.006, respectively). The patients carrying 1 or 2 risk alleles and the patients carrying 3 or 4 risk alleles had worse MST than the patients without the rs7265992A and rs725521C risk alleles (24.0 and 22.0 versus 30.0 months), with the HR for death being 1.26 (95% CI=1.04-1.54) and with the HR of 1.52 (95%CI=1.18-1.97, P=0.001). Rs2025096 and rs2273684 were not associated with the OS of SCLC patients who received platinum-based chemotherapy. Age ≤ 56, KPS> 80, limited-stage, chemotherapy response and radiation therapy had a remarkably prolonged OS (all P<0.05).@*Conclusions@#These results suggest that GSS genetic polymorphism rs725521 plays an important role in the response to platinum-based chemotherapy, while rs7265992 and rs725521 have important effect on the prognosis of SCLC patients, which may be potential genetic biomarkers for personalized treatment of SCLC.

Genetic variation in SDC2 is associated with the risk of radiation esophagitis in patients with esophageal squamous cell carcinoma receiving radiotherapy / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To explore the associations between the genetic variations in the SDC2 gene and overall survival and risk of radiation esophagitis in patients with esophageal squamous cell carcinoma (ESCC).</p><p><b>METHODS</b>Eleven functional haplotype-tagging single nucleotide polymorphisms (htSNPs) of SDC2 were genotyped in 296 ESCC patients who received radiotherapy alone, and had different response and esophagitis. The associations between genotypes and risk of esophagitis were measured by odds ratios (ORs) and 95% confidence intervals (CIs), adjusted for sex, age, tumor location, staging, radiotherapy mode and total radiation dose. The hazard ratios (HRs) were estimated using Cox proportional hazards regression model.</p><p><b>RESULTS</b>The median survival time (MST) of these patients was 14 months. Of them, 260 (87.8%) had died until the last date of follow-up of 30 June, 2014. Clinical stage (stage IV vs. stage II) and total radiation dose (≥ 60 Gy vs. < 60 Gy) influence the overall survival time of the patient significantly. Cox proportional hazards regression model analysis showed that the subjects with rs61599409 T allele had an decreased hazard ratio as compared with those with C allele (adjusted HR = 0.82, 95% CI, 0.66-1.02), but the difference was not statistically significant (P = 0.071). The rest 10 htSNPs were not associated with the overall survival of ESCC patients treated with radiotherapy. Among this set of patients, 160 (54.1%) suffered from radiation esophagitis. We found that rs17788084 A > T SNP in the 3'-untranslational region of SDC2 was associated with esophagitis risk, with the OR being 0.48 (95% CI = 0.28-0.85, P = 0.011) for the TA or TT genotype compared with the AA genotype.</p><p><b>CONCLUSIONS</b>These results suggest that rs17788084 genetic variation in SDC2 is associated with risk of radiation esophagitis and might serve as a potential biomarker for personalized radiotherapy of ESCC.</p>

Genome-wide association study based risk prediction model in predicting lung cancer risk in Chinese / 中华流行病学杂志

<p><b>OBJECTIVE</b>To evaluate the predictive power of risk model by combining traditional epidemiological factors and genetic factors.</p><p><b>METHODS</b>Our previous GWAS data of lung cancer in Chinese were used in training set (Nanjing and Shanghai: 1473 cases vs. 1962 control) and testing set (Beijing and Wuhan: 858 cases vs. 1 115 control). All the single nucleotide polymorphisms (SNPs) associated with lung cancer risk were systematically selected and stepwise logistic regression analysis was used to select independent factors in the training set. The wGRS (weighted genetic score) was further used to calculate genetic risk score. To evaluate the contribution of the genetic factors, 3 risk models were established by using the training set, i.e. smoking model (based on smoking status) , genetic risk model (based on genetic risk score) and combined model (based on smoke and genetic risk score). The predictability of the models were evaluated by the areas under the receiver operating characteristic (ROC) curves, area under curve (AUC), net reclassification improvement (NRI) and integrated discrimination index (IDI). Besides, the results were further verified in the testing set.</p><p><b>RESULTS</b>In the training set, it was found that the AUC of the smoking, genetic risk and combined models were 0.65 (0.63-0.66), 0.60 (0.59-0.62) and 0.69 (0.67-0.71), respectively. Compared with combined model, the predictive power of other two models significantly declined, the difference was statistically significant (P<0.001). Furthermore, compared with the smoking model, the NRI of the combined model increased by 4.57% (2.23%-6.91%) and IDI increased by 3.11% (2.52%-3.69%) in the training set, the difference was statistically significant (P<0.001). Similarly, in the testing set NRI increased by 2.77%, the difference was not statistically significant (P=0.069) , and IDI increased by 3.16%, the difference was statistically significant (P<0.001).</p><p><b>CONCLUSION</b>This study showed that combining 14 genetic variants with traditional epidemiological factors could improve the predictive power of risk model for lung cancer. The model could be used in the screening of high-risk population of lung cancer in Chinese and provide evidence for the early diagnosis and treatment of lung cancer.</p>

Progress in single nucleotide polymorphism with cancer susceptibility and its clinical application / 中华检验医学杂志

Single nueleotide polymorphisms (SNPs) are the most common genetic variants in human genome.Candidate gene,genome-wide association studies (GWASs) and exome sequencing which base on SNPs have made a great progress in identifying cancer susceptibility.The development and application of high resolutions in SNPs has played an important role in clarifying the mechanism,prevention,diagnosis and targeted therapy in cancers.

Association of single nucleotide polymorphisms with radiation-induced esophagitis / 中华放射肿瘤学杂志

Objective To evaluate the relationship between single nucleotide polymorphism(SNP) of candidate genes and radiation-induced esophagitis (RIE) in patients with lung cancer. Methods Between Jan. 2004 and Aug. 2006,170 patients with pathologically diagnosed lung cancer were enrolled in this study. The total target dose was 45-70 Gy( median 60 Gy). One hundred and thirty-two patients were treated with three-dimensional conformal radiotherapy(3DCRT) and 38 with two-dimensional radiotherapy(2DRT).Forty-one patients received radiotherapy alone, 78 received sequential chemoradiotherapy and 51 received concurrent chemoradiotherapy. Thirty-seven SNPs in 20 DNA repair genes were analyzed by using PCR-based restrieted fragment length polymorphism(RFLP). These genes were apoptosis and inflammatory cytoking genes including ATM, ERCC1, XRCC3, XRCC1, XPD, XPC, XPG, NBS1, STK15, ZNF350, ADPRT,TP53, FAS, FASL, CYP2D6 * 4, CASPASE8, COX2,TGF-β, CD14 and ACE. The endpoint was grade ≥2 R I E. Results Forty of the 170 patients developed grade ≥2 R I E, including 36 in grade 2 and 4 in grade 3. Univariate analysis revealed that radiation technique and concurrent chemoradiotherapy were statistically significant relatives to the incidence of R I E (P = 0. 032,0.049) , and both of them had the trend associating with the esophagitis( P = 0.072,0. 094 ). An increased incidence of esophagitis was observed associating with the TGF-β1-509T and XPD 751 Lys/Lys genotypes ( χ2 = 5.65, P = 0.017 ;χ2 = 3.84, P = 0. 048 )in multivariate analysis. Conclusions Genetic polymorphisms in TGF-β1 gene and XPD gene have a significant association with radiation-induced esophagitis.

Study on the association between smoking behavior and dopamine receptor D2 gene polymorphisms among lung cancer cases / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate the possible association between dopamine D2 receptor (DRD2) TaqI A and TaqI B genotypes as well as smoking behavior and the risk of lung cancer among Chinese Han people.</p><p><b>METHODS</b>PCR was used to perform genotyping on peripheral WBC DNA from 326 lung cancer patients and 326 age, sex and ethnicity-matched healthy controls. Subjects were interviewed to obtain relevant information and lifetime history of tobacco use.</p><p><b>RESULTS</b>There were no statistically significant differences in the distribution of DRD2 genotypes between lung cancer cases and controls. The DRD2 genotypes and smoking status showed no correlation among cases and among controls as well. However, among controls, the frequency of the DRD2 * A2/A2 genotype in smokers who smoked > or = 25 cigarettes/day appeared to be higher than that in those who smoked < 25 cigarettes/day (42.5% versus 26.1%, P = 0.047). A similar trend was also found for the DRD2 * B2/B2 genotype, which was linked to the DRD2 * A2/A2 genotype, although the difference was not significant (40.0% versus 26.1%, P = 0.091). In contrast to controls, no association was found between the DRD2 genotypes and smoking among lung cancer cases.</p><p><b>CONCLUSION</b>Our results suggested that DRD2 * A2/A2 genotype might be associated with a greater smoking intensity in Chinese. Further studies are needed to confirm this preliminary finding.</p>

p53 gene codon 72 polymorphism and susceptibility to esophageal squamous cell carcinoma in a Chinese population / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the relationship between p53 codon 72 polymorphism and susceptibility to esophageal squamous cell carcinoma in China.</p><p><b>METHODS</b>The p53 genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism among 204 healthy controls and 91 patients with esophageal squamous cell carcinoma (ESCC).</p><p><b>RESULTS</b>There was no significant difference between patients and controls with respect to allele frequency for the p53 Pro allele (0.480 versus 0.588, P=0.11); however, the Pro/Pro genotype of p53 among cases (39.6%) was significantly (P<0.05) more frequent than that among controls (21.1%). Subjects homozygous for the p53 Pro allele had a more than 2-fold increased risk of developing ESCC (OR=2.18; 95%CI=1.10-4.35, adjusted for age, sex, and smoking), whereas the Arg/Pro genotype was not associated with elevated risk of the cancer (adjusted OR=0.84; 95%CI=0.42-1.68). No interaction between smoking and Pro/Pro genotype was observed for risk of ESCC.</p><p><b>CONCLUSION</b>The p53 codon 72 polymorphism may play a role in susceptibility to esophageal carcinogenesis.</p>

Lung cancer risk associated with genetic polymorphism in myeloperoxidase (-463 G/A) in a Chinese population / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To examine the relationship between susceptibility to lung cancer among Chinese and genetic polymorphism at nucleotide -463 (G/A) in myeloperoxidase (MPO), an enzyme found in lysosomes of phagocytes and involved in the formation of hydroxyl radicals and activation of various smoking-related carcinogens.</p><p><b>METHODS</b>The association of this polymorphism with lung cancer in a hospital-based case-control study of 314 patients and 320 age- and sex-matched controls was tested. The MPO genotypes were determined by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP).</p><p><b>RESULTS</b>The allele frequency for MPO-463A was found to be 11.0% for controls, compared with 15.0% for patients. Multivariate analysis showed an increased risk for overall lung cancer in subjects having GG genotype (OR, 1.7; 95% CI, 1.2 - 2.5), however, the elevated risk was limited to squamous cell carcinoma (OR, 2.4; 95% CI, 1.4 - 3.9; n = 177) but not to adenocarcinoma (OR, 1.3; 95% CI, 0.8 - 2.1; n = 137). In addition, the risky effect of the GG genotype on squamous cell carcinoma of the lung was evident only in the smokers and those who smoked >/= 26 pack-years (OR, 20.5; 95% CI, 5.6 - 75.3) as compared with GA and AA genotypes (OR, 6.2; 95% CI, 1.7 - 22.5) but not in the nonsmokers or those who smoked < 26 pack-years.</p><p><b>CONCLUSION</b>Our data support the hypothesis that -463A polymorphism in the MPO gene may reduce the susceptibility to lung cancer in the Chinese.</p>

Relationship between genetic polymorphism of methylenetetrahydrofolate reductase and the risk of acute lymphocytic leukemia / 解放军医学杂志

Objective To investigate the relationship between genetic polymorphism of methylenetetrahydrofolate reductase (MTHFR) and the risk of acute lymphocytic leukemia (ALL). Methods Eighty-three patients with ALL and a cohort of 83 matched healthy objects were included, and DNA was extracted from their peripheral blood. PCR-RFLP was used to determine the genotypes of MTHFR C677T and A1298C. The adjusted odds ratio (OR) and 95% confidence interval (CI) were calculated using unconditional logistic regression model. Results It was found that the frequency of the MTHFR C677T TT genotype among patients was significantly different from that among control objects (P=0.008). The MTHFR C677T TT genotype had an increased risk of ALL compared with that of 677CC genotype (OR=3.229, 95%CI: 1.328-7.847, P=0.01). No significant association between the MTHFR C677T CT genotype or A1298C polymorphism and the risk of leukemia. Conclusion The present findings suggest that 677C→T polymorphism in MTHFR may be a genetic susceptibility factor for acute lymphocytic leukemia.

CYP1A1 Gene Mutation and Susceptibility to Lung Cancer / 基础医学与临床

Individual susceptibility to cancer induced by environmental agents may be influenced by polymorphic metabolic genes responsible for the activation or detoxification of carcinogens．The association between genetic polymorphisms in cytochrome P4501A1 (CYP1A1) and lung cancer susceptibility has been extensively studied．The various CYP1A1 alleles exhibit population frequencies that depend on race and ethnicity．An increased risk of lung cancer in Asians was found to be associated with genetic polymorphisms in CYP1A1．However，reports from Caucasians are not consistant，probably suggesting the ethnic-sepecific effect of the polymorphisms in the locus on the cancer．Evidence also exists for the association between levels of carcinogen-DNA adducts or frequency of oncogene and tumor suppressor gene mutations and CYP1A1 polymorphisms．These findings provide a better understanding of the relationship between CYP1A1 and lung cancer susceptibility．

DAILY DIETARY INTAKES OF NITRATE, NITRITE AND VITAMIN C IN POPULATIONS AT DIFFERENT RISK OF GASTRIC CANCER / 营养学报

Daily dietary intakes of nitrate, nitrite and vitamin C were investigated in Chanle county, Fujian province, where gastric cancer was very common, with a marked geographic variation in mortality. The average daily intake of nitrate of residents in Zhanggang village (high risk area) was 132.75 mg, which was significantly higher than that (84.65 mg) in Shouzhan village (moderate risk area), but similar to that (113.12 mg) in Meihua village (low risk area). However, nitrite intake in Zhanggang village was greatly higher than that in Shouzhan and Meihua villages (3.36 mg vs 0.21 and 0.37 mg, respectively). The average daily intake of vitamin C in Shouzhan village was 56.37 mg, significantly lower than that in Zhanggang village (123.09 mg) and in Meihua village (105.90 mg). The molar ratio of vitamin C intake to nitrite in the three villages was 3.22, 3.30 and 4.33, respectively. It was invesely associated with the mortality of gastric cancer. The results suggested that nitrate and nitrite might be etiological factors of gastric cancer in the county.