[Associations of genetic variations in pyroptosis related genes with acute adverse events in postoperative rectal cancer patients receiving concurrent chemoradiotherapy].

Objective: This study aims to investigate the associations between genetic variations of pyroptosis pathway related key genes and adverse events (AEs) of postoperative chemoradiotherapy (CRT) in patients with rectal cancer. Methods: DNA was extracted from the peripheral blood which was collected from 347 patients before CRT. Sequenom MassARRAY was used to detect the genotypes of 43 haplotype-tagging single nucleotide polymorphisms (htSNPs) in eight pyroptosis genes, including absent in melanoma 2 (AIM2), caspase-1 (CASP1), caspase-4(CASP4), caspase-5 (CASP5), caspase-11 (CASP11), gasdermin D (GSDMD), gasdermin E (GSDME) and NLR family pyrin domain containing 3 (NLRP3). The associations between 43 htSNPs and AEs were evaluated by the odd ratios (ORs) and 95% confidence intervals (CIs) by unconditional logistic regression models, adjusted for sex, age, clinical stage, tumor grade, Karnofsky performance status (KPS), surgical procedure, and tumor location. Results: Among the 347 patients with rectal cancer underwent concurrent CRT with capecitabine after surgery, a total of 101(29.1%) occurred grade ≥ 2 leukopenia. rs11226565 (OR=0.41, 95% CI: 0.21-0.79, P=0.008), rs579408(OR=1.54, 95% CI: 1.03-2.29, P=0.034) and rs543923 (OR=0.63, 95% CI: 0.41-0.98, P=0.040) were significantly associated with the occurrence of grade ≥ 2 leukopenia. One hundred and fifty-six (45.0%) had grade ≥ 2 diarrhea, two SNPs were significantly associated with the occurrence of grade ≥ diarrhea, including CASP11 rs10880868 (OR=0.55, 95% CI: 0.33-0.91, P=0.020) and GSDME rs2954558 (OR=1.52, 95% CI: 1.01-2.31, P=0.050). In addition, sixty-six cases (19.0%) developed grade ≥2 dermatitis, three SNPs that significantly associated with the risk of grade ≥2 dermatitis included GSDME rs2237314 (OR=0.36, 95% CI: 0.16-0.83, P=0.017), GSDME rs12540919 (OR=0.52, 95% CI: 0.27-0.99, P=0.045) and NLRP3 rs3806268 (OR=1.51, 95% CI: 1.03-2.22, P=0.037). There was no significant difference in the association between other genetic variations and AEs of rectal cancer patients (all P>0.05). Surgical procedure and tumor location had great impacts on the occurrence of grade ≥2 diarrhea and dermatitis (all P<0.01). Conclusion: The genetic variants of CASP4, CASP11, GSDME and NLRP3 are associated with the occurrence of AEs in patients with rectal cancer who received postoperative CRT, suggesting they may be potential genetic markers in predicting the grade of AEs to achieve individualized treatment of rectal cancer.

Sandwich excision in patients with placenta percreta involving maternal bladder.

OBJECTIVE: Our aim is to describe and assess a Sandwich Excision (placenta-uterine-bladder excision together) surgical technique for women with clinically confirmed placenta percreta involving the maternal bladder. PATIENTS AND METHODS: A retrospective cohort study was performed on all patients with clinically confirmed placenta percreta involving the maternal bladder who underwent Sandwich Excision at our large academic institution from January 1, 2014, to June 30, 2019. RESULTS: Twenty-three patients were included. Four patients underwent hysterectomy, and one patient underwent subhysterectomy. The mean duration of surgery was 228.04 ± 85.59 minutes (range, 90.00-503.00 minutes). The mean estimated blood loss was 5,269.57 ± 2,745.81 mL (range, 1,000.00-12,500.00 mL). No thromboembolic events occurred, and there were no maternal or neonatal deaths among the subjects in this study. CONCLUSIONS: Sandwich excision is associated with a low rate of hysterectomy in women with placenta percreta involving the maternal bladder. The procedure is a relatively safe technique and can be performed safely by experienced obstetricians who are familiar with the uterus-bladder space. Meanwhile, the success rates and complications of the Sandwich Excision in these patients also need to be evaluated in prospective studies.

[Genetic variations in apoptosis genes are associated with acute adverse events in postoperative rectal cancer patients receiving concurrent chemoradiotherapy].

Objective: To investigate the associations between the genetic variations of apoptosis genes and the adverse events of postoperative concurrent chemoradiotherapy in patients with rectal cancer. Methods: We enrolled 362 patients with stage Ⅱ to Ⅲ rectal cancer who received concurrent chemoradiotherapy. Whole blood sample (2 ml) was collected from patient at the time of enrollment before therapy. Sequenom MassARRAY was used to detect the genotypes of 29 haplotype-tagging single nucleotide polymorphisms (htSNPs) in eight apoptosis genes, including Fas cell surface death receptor(FAS), Fas ligand(FASL), apoptotic peptidase activating factor 1(APAF1), BCL2 associated X(BAX), TNF-related apoptosis-inducing ligand(TRAIL), TNF-related apoptosis-inducing ligand receptor 1(TRAILR1), TNF-related apoptosis-inducing ligand receptor 2(TRAILR2) and caspase-7(CASP7). The associations between genotypes and adverse events of chemoradiotherapy were measured by unconditional logistic regression model. Results: Three hundred and sixty two patients were treated with total mesorectal excision surgery followed by a total radiation dose of 50 Gy applied in 25 fractions over a period of 5 weeks concurrently with daily administration of capecitabine (1 600 mg/m(2) per day, continuously for 2 weeks and taking a week off every 21-day cycle). One hundred and six patients (29.3%) had grade≥2 myelosuppression. Three SNPs associated with the risk of grade ≥2 myelosuppression included FAS rs1468063 (OR=1.51, 95% CI: 1.07-2.15, P=0.020), APAF1 rs11296996 (OR=0.69, 95% CI: 0.49-0.98, P=0.039) and BAX rs4645904 (OR=0.69, 95% CI: 0.50-0.97, P=0.030). One hundred and sixty one patients (44.5%) developed grade≥2 diarrhea. Five SNPs that significantly associated with risk of grade≥2 diarrhea included APAF1 rs11296996 (OR=1.42, 95% CI: 1.02-2.00, P=0.040), rs74619561 (OR=2.16, 95% CI: 1.27-3.68, P=0.005), CASP7 rs12263370 (OR=1.67, 95% CI: 1.05-2.66, P=0.029), rs12247479 (OR=1.85, 95% CI: 1.12-3.08, P=0.017) and TRAIL rs112822654 (OR=0.68, 95% CI: 0.48-0.96, P=0.027). The remaining SNPs were not related to the adverse events of chemoradiotherapy (all P>0.05). Grade≥2 myelosuppression occurred less frequently in male than in female (P=0.046); Surgical treatment and tumor location had great impact on the occurrence of grade≥2 diarrhea (all P<0.001) and dermatitis (all P<0.05). Conclusions: The genetic variations of FAS, APAF1, BAX, TRAIL and CASP7 are related to the adverse events of concurrent chemoradiotherapy in patients with rectal cancer, which may be potential genetic biomarkers for individualized treatment of rectal cancer.

[Genetic variation in DNA polymerase kappa gene is associated with the prognosis after platinum-based chemotherapy in small cell lung cancer patients].

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.

[Genetic variations in MLH3 and MSH2 genes are associated with the sensitivity and prognosis in locally advanced rectal cancer patients receiving preoperative chemoradiotherapy].

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.

[Correlations between genetic variations of glutathione synthetase gene and the response to platinum-based chemotherapy and prognosis of small cell lung cancer patients].

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 DNA repair gene RAD52 is associated with the response to platinum-based chemotherapy in SCLC patients].

OBJECTIVE: To explore the associations between genetic variations of DNA repair gene RAD52 and response to platinum-based chemotherapy of small cell lung cancer (SCLC), and to analyze the influencing factors on survival. METHODS: Nine haplotype-tagging single nucleotide polymorphisms (htSNPs) of RAD52 were genotyped by Sequenom Mass ARRAY technology in 939 SCLC patients who received platinum-based chemotherapy, and had different response and survival time. The associations between genotypes and platinum-based chemotherapy response were analyzed by odds ratios (ORs) and 95% confidence intervals (CIs), adjusted for sex, age, smoking, KPS, staging and chemotherapy regimens, by unconditional logistic regression model. The relative ratios (RRs) were estimated using Cox proportional hazards regression model. RESULTS: Among the 939 cases, 483 (51.4%) cases received cis-platinum and etoposide treatment while others treated with carboplatin and etoposide. Six hundred and eighty two 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 months. We found that rs10774474 SNP which located in the 5'-flanking region of RAD52 was significantly associated with chemotherapy response. Compared with the TT genotype, patients with TA and AA genotype had a worse chemotherapy response and increased risk of no-response (P=0.004). Correlation analysis showed that patients with KPS >80 had a better chemotherapy response than those with KPS≤80 (P=0.001). The patients with extensive-stage had a worse chemotherapy response than those with limited-stage (P<0.001). Cox proportional hazards regression model analysis showed that nine htSNPs of RAD52 were not associated with the overall survival (OS) of SCLC patients who received platinum-based chemotherapy. Age≤56, KPS>80, limited-stage, chemotherapy response and radiation therapy can remarkably prolong OS (allP<0.05). CONCLUSIONS: These results suggest that RAD52 genetic polymorphism rs10774474 plays an important role in the response to platinum-based chemotherapy, and may be a potential genetic biomarker for SCLC personalized treatment.

Cryptorchidism in LhrKO animals and the effect of testosterone-replacement therapy.

BACKGROUND: The objective of the current study was to characterize the morphological and genetic basis of cryptorchidism. METHODS AND RESULTS: We investigated cryptorchidism in LH receptor (Lhr) knockout (LhrKO) mice and how testosterone-replacement therapy (TRT) worked to correct the phenotype. The results revealed that while gubernacular development was indistinguishable between Lhr-null and wild-type animals until 7 days of age, it was subsequently severely impaired in null animals. This was due to a reduction in mesenchymal cell division, differentiation into cremaster muscle cells and their delayed maturation. While transcript levels of Hoxa10, Hoxa11, Desrt and Dll1 were indistinguishable, the levels of Notch1, Numb and Lgr8 in the gubernaculum and Insl3 in the testes were lower in Lhr-null than in wild-type siblings. The TRT, which completed testicular descent into the scrotum, corrected the morphological changes and the expression of Lgr8, Numb and Notch, but not Insl3, to wild-type levels. Transection of the genitofemoral nerve did not prevent the TRT effect. CONCLUSION: In summary, cryptorchidism in Lhr-null animals was caused by defects in the gubernacular development due to testosterone deficiency. TRT reversed all the morphological and gene expression changes except Insl3, suggesting that testosterone, not INSL3, secreted by Leydig cells, facilitates the completion of testicular descent.

Targeted disruption of LH receptor gene revealed the importance of uterine LH signaling.

Numerous previous studies have demonstrated that LH and hCG can directly regulate several uterine functions. We investigated in the present study, whether uterine phenotype in LH receptor knockout animals resulted also from the absence of direct actions of LH in the uterus. The phenotype consisted of marked growth reduction of uterus, decreased thickness of endometrial and myometrial layers, number of endometrial glands, height of luminal epithelium and vascular space. Analysis of uterine gene expression by mouse genome U74Av2 Affymetrix genechips revealed a differential expression of 155 genes by more than 3-fold (range 3-53-fold) between null and wild-type animals. Of these, 89 genes decreased and 66 increased in uterus of null animals. Semi-quantitative RT-PCR confirmed the differential expression of several selected genes. The decreased genes can be clustered into 18 functional families and the increased into 15 functional families. Semi-quantitative RT-PCR, Western blotting and immunocytochemistry demonstrated a decreased expression of ERbeta, PR-A, PR-B and AR in uterus of null animals as compared with wild-type siblings. Twenty-one-day estradiol and progesterone replacement therapy did not normalize the decrease in the number of endometrial glands and several genes that either decreased or increased in expression. The partial success of therapy suggests that direct LH actions could be required to completely normalize the uterus. In summary, findings on the knockout model reaffirm that LH and hCG control uterine functions directly as well as indirectly through increasing ovarian synthesis of steroid hormones and both actions are required for normal uterine biology.

Dependence of uterine cyclooxygenase2 expression on luteinizing hormone signaling.

Several previous studies have demonstrated that uterine Cox2 (also known as Ptgs2) is required for implantation. Luteinizing hormone (LH) released from anterior pituitary gland and human chorionic gonadotropin released from placenta (hCG) can upregulate the uterine Cox2 gene expression. The Lhcgr knockout (herein designated LHRKO) animals have implantation failure even after estradiol and progesterone therapy. These findings led us to investigate the dependence of uterine Cox2 gene expression on LH signaling in LHRKO animals. The results revealed that, while Cox1 (also known as Ptgs1) mRNA levels were similar, Cox2 mRNA levels were lower in uterus of null animals than in wild-type siblings. Treatment with hCG did not increase Cox2 mRNA levels in null endometrial stromal or myometrial smooth-muscle cells unless gene therapy was performed to introduce native LHCGR. The Cox1 mRNA levels, on the other hand, did not change regardless of the introduction of native or activated Lhcgr or hCG treatment. The Cox2 mRNA increase paralleled the cAMP raise, suggesting that LH uses the cAMP second messenger system. Treating the wild-type uterine cells with hCG resulted in a Cox2 but not Cox1 mRNA increase. This increase became exaggerated when additional native LHCGR were introduced by gene therapy. In conclusion, deletion and reinsertion of Lhcgr further support that uterine Cox2 gene expression is dependent on LH signaling.

Expression of COX-2 in stomach cancers and its relation to their biological features.

BACKGROUND/AIM: Cyclooxygenase-2 (COX-2) is one of the key isoenzymes in the production of prostaglandins, and is believed to be involved in carcinogenesis. This study was conducted to examine the role of COX-2 in the development and biological behavior of stomach cancer. METHODS: Expression of COX-2 at the mRNA and protein levels was analyzed using RT-PCR and immunoblotting assay in 50 cancerous and corresponding non-cancerous tissue specimens. Also, COX-2 expression was detected by an immunohistochemical method in 55 paraffin-embedded gastric adenocarcinoma tissues. RESULTS: Of the 50 carcinoma tissue samples analyzed, 38 (76.0%) had overexpression of COX-2 as compared to the paired non-cancerous specimens. The overexpression of COX-2 (91.7%) was more prevalent in tumors with sizes of >5 cm than those (61.5%) of 6 metastatic nodes compared to those with

Ser326Cys polymorphism in hOGG1 gene and risk of esophageal cancer in a Chinese population.

Ser326Cys polymorphism in the hOGG1 gene, which is involved in the repair of 8-hydroxyguanine in oxidatively damaged DNA, has been identified and the variant genotype appears to be related to susceptibility to certain cancers. We investigated the association between Ser326Cys polymorphism and squamous-cell carcinoma of the esophagus among a Chinese population. hOGG1 gene polymorphism was detected by PCR-based single-strand conformation polymorphism and DNA sequencing among 201 normal controls and 196 patients with esophageal cancer from Linxian, China, a high-risk area for the disease. The association between this genetic polymorphism and risk of the cancer was examined by a multivariate analysis. We found that the distribution of hOGG1 Ser326Cys genotypes among controls (Ser/Ser, 33.8%; Ser/Cys, 52.8%; and Cys/Cys, 13.4%) was significantly different from that among esophageal cancer cases (39.8%, 38.8% and 21.4%, respectively) (p < 0.05). Homozygosity for the Cys/Cys genotype significantly increased the risk of developing esophageal squamous-cell carcinoma, with the odds ratio (OR) adjusted for age, sex and smoking being 1.9 (95% confidence interval [CI] = 1.3-2.6). Although smoking alone also significantly increased esophageal cancer risk in this case-control study (adjusted OR = 2.6; 95% CI = 1.7-3.9), no significant interaction between smoking and the Cys/Cys genotype was observed in terms of risk. Our results suggest that the hOGG1 326Cys allele might play a role in the carcinogenesis of the esophagus.

Frequency of CYP2A6 gene deletion and its relation to risk of lung and esophageal cancer in the Chinese population.

Cytochrome P450 2A6 (CYP2A6) plays an important role in the oxidation of nicotine and in the activation of tobacco-related carcinogens, such as N-nitrosodimethylamine, N-nitrosodiethylamine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone. It has been suggested that individuals with defective CYP2A6 alleles are at a lower risk of becoming smokers and of developing lung and other tobacco-related cancers. We examined the relationship between the CYP2A6 gene deletion and susceptibility to lung and esophageal cancer in a Chinese population via a hospital-based case-control study. The CYP2A6 gene deletion was determined by a PCR-based approach in 326 healthy controls, 149 patients with esophageal squamous-cell carcinoma and 151 patients with lung cancer. The allele frequency of the CYP2A6*4 deletion was 8.6% among controls compared with 8.4% among cases with esophageal squamous-cell carcinoma (p = 0.29) or 13.2% among cases with lung cancer (p < 0.01). Individuals who harbored at least one CYP2A6*4 deletion allele were at a 2-fold increased risk of developing lung cancer (95% confidence interval [CI] = 1.2-3.2) compared with those without a defective CYP2A6 allele. This effect was mainly limited to squamous-cell carcinoma and to non-smokers, although a joint effect of CYP2A6 deletion and tobacco smoking on lung cancer risk was observed among heavy smokers. The overall risk of esophageal cancer did not appear to be associated with this CYP2A6 genetic polymorphism (odds ratio [OR] = 1.2, 95% CI = 0.7-2.1). However, stratified analysis suggested an excess risk with borderline significance (OR = 2.1; 95% CI = 1.0-4.5) related to the CYP2A6*4 allele among non-smokers. The distribution of CYP2A6 genotype frequency was not significantly different (p = 0.40) between smokers (n = 174) and non-smokers (n = 152) in this study population. Our results demonstrate that the CYP2A6 gene deletion is associated with an increased risk of lung and esophageal cancer but not with a reduced tendency to smoke.

Impact of genetic polymorphisms in cytochrome P450 2E1 and glutathione S-transferases M1, T1, and P1 on susceptibility to esophageal cancer among high-risk individuals in China.

Esophageal cancer, which is prevalent in China, is believed to be induced by environmental carcinogens such as nitrosamines and other agents. The disproportionate geographical distribution of this cancer among individuals suggests a role for gene-environment interactions in developing the disease. We have shown in our preliminary study that a genetic polymorphism in cytochrome P450 2E1 (CYP2E1) that is known to activate nitrosamines may be a susceptibility factor involved in the early events leading to the development of esophageal cancer (Lin et al., Cancer Epidemiol. Biomark. Prev., 7: 1013-1018, 1998). This relatively larger study was conducted to compare the results with our previous findings. One hundred and fifty cases with esophageal cancer, 146 cases with esophageal dysplasia, and 150 normal controls were residents of Linxian, China, a high-risk area. Genomic DNA samples were assayed for restriction fragment length polymorphisms in the CYP2E1 and GSTP1 loci by PCR amplification followed by digestion with RsaI and Alw26I, respectively. Deletion of the GSTM1 and GSTT1 genes was detected by multiplex PCR. The distribution of CYP2E1 c1/c1 allele frequency was found to be significantly different between controls (44.0%) and cases with cancer (71.3%) or cases with dysplasia (70.6%; P < 0.0001). Individuals having the c1/c1 genotype were at a 3.1-fold [95% confidence interval (CI), 2.4-3.9] increased risk of developing dysplasia and a 3.2-fold (95% CI, 2.5-4.1) increased risk of developing squamous cell carcinoma of the esophagus. Although polymorphisms in the GSTT1 and GSTP1 were not significantly different between cases with cancer or cases with dysplasia and controls, the frequency of the GSTM1 non-null (+/+ and +/0) genotypes appeared to be overrepresented in cases with cancer compared with controls (odds ratio, 2.3; 95% CI, 1.8-3.0). Furthermore, a joint effect of the CYP2E1 c1/c1 genotype and GSTM1 non-null genotype on the cancer risk was observed, showing an odds ratio of 8.5 (95% CI, 3.7-19.9). These results demonstrate that CYP2E1 and perhaps GSTM1 are genetic determinants in the development of squamous cell carcinoma of the esophagus.

Human CYP1B1 Leu432Val gene polymorphism: ethnic distribution in African-Americans, Caucasians and Chinese; oestradiol hydroxylase activity; and distribution in prostate cancer cases and controls.

Cytochrome P4501B1 (CYP1B1) is involved in the activation of many carcinogens and in the metabolism of steroid hormones, including 17beta-oestradiol (E2) and testosterone. We report a significant difference in the allele frequencies of two point mutations in the coding region of the CYP1B1 gene among Caucasian (n = 189), African-American (n = 52) and Chinese (Linxian) (n = 109) populations. A (C to G) transversion at position 1666 in exon 3, which results in an amino acid substitution of Leu432 to Val, was present in African-Americans with an allele frequency for Va1432 of 0.75, in Caucasians of 0.43, and in Chinese of 0.17. A (C to T) transition at position 1719 in exon 3, with no amino acid change (Asp449), appeared to be closely linked with the Val432 variant. Results using human lung microsomal preparations from individuals with the CYP1B1Val/Val and CYP1B1Leu/Leu genotypes indicate that Val432 variant may be a high activity allele and thus may contribute to the interindividual differences in CYP1B1 activity. Because CYP1B1 is involved in hormone and carcinogen metabolism, and given the disparate rates of prostate cancer among ethnic groups, we also evaluated the association of the CYP1B1 Leu432Val polymorphism with prostate cancer risk in a pilot case-control study. Among Caucasians, 34% of men with cancer (n = 50) were homozygous for the Val432 polymorphism, while only 12% of matched control subjects (n = 50) had this genotype. These preliminary data indicate that genetic polymorphisms in CYP1B1 might play an important role in human prostate carcinogenesis.

Low frequency of CYP2A6 gene polymorphism as revealed by a one-step polymerase chain reaction method.

Human cytochrome P450 2A6 (CYP2A6) has been shown to metabolically activate carcinogens and mutagens. Genetic polymorphisms for CYP2A6 have been reported previously in different ethnic groups using a two-step polymerase chain reaction (PCR) method to identify CYP2A6*1, CYP2A6*2 and CYP2A6*3. Moreover, a new truncated allele has been recently identified in a Japanese population. We report here a one-step PCR amplification of the CYP2A6 gene from human genomic DNA and the detection of intact CYP2A6 alleles by restriction enzyme digestion. The diagnostic exon (exon 3) of the CYP2A6 gene was amplified from human genomic DNA with a primer pair. The forward primer is unique to the CYP2A6 gene, which eliminates previous problems in amplifying two highly homologous CYP2A genes, CYP2A7 and CYP2A13, in humans. The resulting PCR products (214 bp) were digested with XcmI or DdeI to detect the presence of CYP2A6*2 or CYP2A6*3 alleles, respectively. The allelic frequencies for CYP2A6*2 were 2.3% (n = 320) in the Caucasian and 0.7% (n = 71) in the Chinese populations, respectively. CYP2A6*3 allelic frequency in the Chinese population was 0.7%; while no CYP2A6*3 allele was detected in the Caucasian population. The allelic frequencies are relatively low and the reason for this discrepancy between different methods is discussed.

Development of an antipeptide antibody that binds to the C-terminal region of human CYP1B1.

An antipeptide antibody was raised against a 14-mer synthetic peptide (CDFRANPNEPA KMN) corresponding to the amino acid sequence from 491 to 504 of human cytochrome P-450 (CYP)1B1. Rabbit-derived antisera demonstrated the ability to induce moderately high antibody titers (>1:10(5)) as judged by enzyme-linked immunosorbent assay. In Western blot analysis, the purified antibody recognized a single protein band (estimated as 56 kDa) in microsomes prepared from human and rodent tissues. No significant cross-reactivity to either human CYP1A1 or human CYP1A2 protein was detected. Titration studies using recombinant human CYP1B1 and an enhanced chemiluminescence-based detection method demonstrated a minimal detection sensitivity for this antiserum at about 0.34 ng/band in 8 x 7-cm minigels. The immunoprecipitation and immunoinhibition results indicate that this antisera recognizes the nondenatured human CYP1B1 protein but does not inhibit its enzyme activity. Using this antibody, CYP1B1 protein was detected in nine different human tissues and in cultured cells induced by various chemicals. This highly specific, highly sensitive antibody provides an important tool to study tissue distribution and cellular expression levels of CYP1B1, with negligible cross-reactivity from the other members of the CYP1 family.

Susceptibility to esophageal cancer and genetic polymorphisms in glutathione S-transferases T1, P1, and M1 and cytochrome P450 2E1.

Genetic polymorphisms in enzymes involved in carcinogen metabolism have been shown to influence susceptibility to cancer. Cytochrome P450 2E1 (CYP2E1) is primarily responsible for the bioactivation of many low molecular weight carcinogens, including certain nitrosamines, whereas glutathione S-transferases (GSTs) are involved in detoxifying many other carcinogenic electrophiles. Esophageal cancer, which is prevalent in China, is hypothesized to be related to environmental nitrosamine exposure. Thus, we conducted a pilot case-control study to examine the association between CYP2E1, GSTM1, GSTT1, and GSTP1 genetic polymorphisms and esophageal cancer susceptibility. DNA samples were isolated from surgically removed esophageal tissues or scraped esophageal epithelium from cases with cancer (n = 45), cases with severe epithelial hyperplasia (n = 45), and normal controls (n = 46) from a high-risk area, Linxian County, China. RFLPs in the CYP2E1 and the GSTP1 genes were determined by PCR amplification followed by digestion with RsaI or DraI and Alw26I, respectively. Deletion of the GSTM1 and GSTT1 genes was examined by a multiplex PCR. The CYP2E1 polymorphism detected by RsaI was significantly different between controls (56%) and cases with cancer (20%) or severe epithelial hyperplasia (17%; P < 0.001). Persons without the RsaI variant alleles had more than a 4-6-fold risk of developing severe epithelial hyperplasia (adjusted odds ratio, 6.0; 95% confidence interval, 2.3-16.0) and cancer (adjusted odds ratio, 4.8; 95% confidence interval, 1.8-12.4). Polymorphisms in the GSTs were not associated with increased esophageal cancer risk. These results indicate that CYP2E1 may be a genetic susceptibility factor involved in the early events leading to the development of esophageal cancer.

Species differences in the biotransformation of the food-borne carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine by hepatic microsomes and cytosols from humans, rats, and mice.

A comparative study on the metabolic activation and detoxification of the food-borne carcinogen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), by human, rat, and mouse hepatic subcellular fractions was conducted to elucidate the mechanism of the interspecies and organ-specific differences in genotoxicity and carcinogenesis. Incubation of PhIP with human, rat, and mouse hepatic microsomes each generated two metabolites, which were identified as N-hydroxy-PhIP and 4'-hydroxy-PhIP. However, the rates of formation of these metabolites differed significantly between species. Human hepatic microsomes had the highest capacity to convert PhIP to the genotoxic metabolite, N-hydroxy-PhIP, with a mean +/- SD value (9.69 +/- 5.15 nmol/mg protein/30 min, N = 3) that was 1.8-fold and 1.4-fold higher than that of rats (5.25 +/- 1.63, N = 3) and mice (6.89 +/- 0.55, N = 3) p < 0.05), respectively. Rodent microsomes were also able to convert PhIP to its nongenotoxic 4'-hydroxy derivative; however, this detoxification pathway was negligible in human hepatic microsomes. The ratio of N-hydroxylation to 4'-hydroxylation was 97:1, 3.3:1, and 1.7:1 for humans, rats, and mice, respectively. The capacities for the further metabolic activation of N-hydroxy-PhIP by cytosolic O-acetyltransferase, sulfotransferase, L-prolyl-tRNA synthetase, and an ATP-dependent kinase(s) were examined using PhIP-DNA binding as a measure of bioactivation. Acetyl coenzyme A-dependent DNA binding of N-hydroxy-PhIP was detected with both human and rodent hepatic cytosols, and showed a significant interspecies difference.(ABSTRACT TRUNCATED AT 250 WORDS)

Advantages and limitations of laboratory methods for measurement of carcinogen-DNA adducts for epidemiological studies.

In molecular epidemiological studies, the measurement of carcinogen-DNA adducts in human tissues can provide direct evidence of current exposure to chemical carcinogens. Moreover, data on steady state DNA adduct levels and the rate of cell proliferation can be related not only to carcinogen-target tissue dosimetry but may also be useful in assessment of human cancer risk. Thus far, laboratory methods for adduct detection have primarily utilized 32P-postlabelling, immunoassays, and mass spectrometry. However, accurate quantitation of DNA adducts requires knowledge of the structural identity and chemical properties of carcinogen-base adducts, the availability of synthetic standards for recovery determinations, and the development of complementary methods to corroborate analytical findings.