CYP1A1 Ile462Val polymorphism contributes to colorectal cancer risk: A meta-analysis

Low-Penetrance Susceptibility Variants in Colorectal Cancer-Current Outlook in the Field

Colorectal cancer (CRC) is one of the most frequent and mortality-causing neoplasia, with various distributions between populations. Strong hereditary predispositions are the causatives of a small percentage of CRC, and most cases have no transparent genetic background. This is a vast arena for exploring cancer low-susceptibility genetic variants. Nonetheless, the research that has been conducted to date has failed to deliver consistent conclusions and often features conflicting messages, causing chaos in this field. Therefore, we decided to organize the existing knowledge on this topic. We screened the PubMed and Google Scholar databases. We drew up markers by gene locus gathered by hallmark: oncogenes, tumor suppressor genes, genes involved in DNA damage repair, genes involved in metabolic pathways, genes involved in methylation, genes that modify the colonic microenvironment, and genes involved in the immune response. Low-penetration genetic variants increasing the risk of cancer are often population-specific, hence the urgent need for large-scale testing. Such endeavors can be successful only when financial decision-makers are united with social educators, medical specialists, genetic consultants, and the scientific community. Countries' policies should prioritize research on this subject regardless of cost because it is the best investment. In this review, we listed potential low-penetrance CRC susceptibility alleles whose role remains to be established.

Assessment of the association of CYP1A1 gene polymorphisms with the susceptibility of cervical cancer: A case-control study and meta-analysis

Background

Cervical cancer (CC) is the second most common type of female malignancy in Bangladesh. Polymorphisms in the CYP1A1 gene have been reported to be associated with CC in different populations. This case-control study with meta-analysis was undertaken to assess the relation of CYP1A1 rs4646903 and rs1048943 polymorphisms with the susceptibility of CC.

Methods

A total of 185 CC patients and 220 controls were recruited, and the PCR-RFLP (Polymerase chain reaction-restriction fragment length polymorphism) technique was applied for genotyping. Again, 42 eligible studies (24 with rs4646903 and 18 with rs1048943) were included for meta-analysis, and RevMan 5.3 and the MetaGenyo web-based tool were used.

Results

The rs4646903 polymorphism was significantly linked with CC in all association models, namely, additive 1, additive 2, dominant, recessive, overdominant, and allele models (OR = 2.41, 4.75, 2.67, 3.61, 2.13, and 2.44 with corresponding 95% CI = 1.55-3.76, 1.81-12.45, 1.75-4.07, 1.39-9.35, 1.38-3.30, and 1.71-3.48, respectively). On the contrary, rs1048943 showed no association (p > 0.05) with CC. Haplotype analysis revealed AT and AC haplotypes significantly decreased (OR = 0.45) and increased (OR = 4.86) CC risk, respectively, and SNPs are in strong linkage disequilibrium (D' = 0.912, r² = 0.448). Again, rs4646903 carriers with a contraception history and >5 years of taking contraceptives showed an enhanced risk of CC (OR = 2.39, OR = 3.05). Besides, rs1048943 carriers aged >40 years (OR = 0.44), conceived first child aged ≤18 years (OR = 3.45), and history of contraceptives (OR = 2.18) were significantly linked with CC. Our meta-analysis found that for CYP1A1 rs4646903 codominant 1 (COD 1), codominant 2 (COD 2), codominant 3 (COD 3), dominant model (DM), recessive model (RM), and allele model (AM) in Caucasians and overdominant model (OD) in the overall population are associated with an elevated risk of CC, whereas rs1048943 is also associated with CC in overall, Caucasians and Asians in some genetic models.

Conclusion

Our case-control study and meta-analysis summarize that CYP1A1 rs4646903 and rs1048943 polymorphisms may be correlated with cervical cancer.

A Study on the Mechanism of Herbal Drug FDY003 for Colorectal Cancer Treatment by Employing Network Pharmacology

Colorectal cancer (CRC) originates from the uncontrolled growth of epithelial cells in the colon or rectum. Annually, 1.9 million new CRC cases are being reported, causing 0.9 million deaths worldwide. The suppressive effects of the herbal prescription FDY003, a mixture of Cordyceps militaris, Lonicera japonica Thunberg, and Artemisia capillaris Thunberg, against CRC have previously been reported. Nonetheless, the multiple compound-multiple target mechanisms of FDY003 in CRC cells have not been fully elucidated. In this study, we used network pharmacology (NP) to analyze the polypharmacological mechanisms of action of FDY003 in CRC treatment. FDY003 promoted the suppression of viability of CRC cells and strengthened their sensitivity to anticancer drugs. The NP study enabled the investigation of 17 pharmaceutical compounds and 90 CRC-related genes that were targets of the compounds. The gene ontology terms enriched with the CRC-related target genes of FDY003 were those involved in the control of a variety of phenotypes of CRC cells, for instance, the decision of apoptosis and survival, growth, stress response, and chemical response of cells. In addition, the targeted genes of FDY003 were further enriched in various Kyoto Encyclopedia of Genes and Genomes pathways that coordinate crucial pathological processes of CRC; these are ErbB, focal adhesion, HIF-1, IL-17, MAPK, PD-L1/PD-1, PI3K-Akt, Ras, TNF, and VEGF pathways. The overall analysis results obtained from the NP methodology support the multiple-compound-multiple-target-multiple-pathway pharmacological features of FDY003 as a potential agent for CRC treatment.

Frequency of CYP1A1*2A polymorphisms and deletion of the GSMT1 gene in a Peruvian mestizo population

The polymorphic variants of CYP1A1 and the deletion of GSTM1 are present in the Peruvian mestizo population. Wild type and mutated genotypes (WT/*2A and *2A/ *2A) were identified, whose allele frequencies are 0.31 (T allele) and 0.69 (C allele), respectively; 53% with wild type GSTM1 (+) and 47% with null GSTM1. The frequency in Iquiteño emigrants was 0.72 CYP1A1*2A and 25% GSTM1 (-); from Lima 0.67 CYP1A1*2A and 33% of GSTM1 (-). The Hardy-Weinberg equilibrium test for the studied population showed that both frequencies are out of balance, p > .05.

The presence of the risk allele of the CYP1A1*2A polymorphism and the deletion in the GSTM1 gene are high, which could be indicative of a phase I and II metabolic imbalance in this group of Peruvian populations, with potential risks of activating agents procarcinogens thus affecting the incidence of tumor pathologies with an environmental component.

Low penetrance genetic polymorphisms as potential biomarkers for colorectal cancer predisposition

Colorectal cancer is a leading form of cancer in both males and females. Early detection of individuals at risk of colorectal cancer allows proper treatment and management of the disease to be implemented, which can potentially reduce the burden of colorectal cancer incidence, morbidity and mortality. In recent years, the role of genetic susceptibility factors in mediating predisposition to colorectal cancer has become more and more apparent. Identification of high-frequency, low-penetrance genetic polymorphisms associated with the cancer has therefore emerged as an important approach which can potentially aid prediction of colorectal cancer risk. However, the overwhelming amount of genetic epidemiology data generated over the past decades has made it difficult for one to assimilate the information and determine the exact genetic polymorphisms that can potentially be used as biomarkers for colorectal cancer. This review comprehensively consolidates, based primarily on results from meta-analyses, the recent progresses in the search of colorectal cancer-associated genetic polymorphisms, and discusses the possible mechanisms involved.

CYP1A1, CYP2E1 and EPHX1 polymorphisms in sporadic colorectal neoplasms

AIM

To investigate the contribution of polymorphisms in the CYP1A1, CYP2E1 and EPHX1 genes on sporadic colorectal cancer (SCRC) risk.

METHODS

Six hundred forty-one individuals (227 patients with SCRC and 400 controls) were enrolled in the study. The variables analyzed were age, gender, tobacco and alcohol consumption, and clinical and histopathological tumor parameters. The CYP1A1*2A, CYP1A1*2C CYP2E1*5B and CYP2E1*6 polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The EPHX1 Tyr113His, EPHX1 His139Arg and CYP1A1*2C polymorphisms were detected by real-time PCR. Chi-squared test and binary logistic regression were used in the statistical analysis. Haplotype analysis was conducted using the Haploview program, version 2.05.

RESULTS

Age over 62 years was a risk factor for SCRC development (OR = 7.54, 95%CI: 4.94-11.50, P < 0.01). Male individuals were less susceptible to SCRC (OR = 0.55, 95%CI: 0.35-0.85, P < 0.01). The CYP2E1*5B polymorphism was associated with SCRC in the codominant (heterozygous genotype: OR = 2.66, 95%CI: 1.64-4.32, P < 0.01), dominant (OR = 2.82, 95%CI: 1.74-4.55, P < 0.01), overdominant (OR = 2.58, 95%CI: 1.59-4.19, P < 0.01), and log-additive models (OR = 2.84, 95%CI: 1.78-4.52, P < 0.01). The CYP2E1*6 polymorphism was associated with an increased SCRC risk in codominant (heterozygous genotype: OR = 2.81, 95%CI: 1.84-4.28, P < 0.01; homozygous polymorphic: OR = 7.32, 95%CI: 1.85-28.96, P < 0.01), dominant (OR = 2.97, 95%CI: 1.97-4.50, P < 0.01), recessive (OR = 5.26, 95%CI: 1.35-20.50, P = 0.016), overdominant (OR = 2.64, 95%CI: 1.74-4.01, P < 0.01), and log-additive models (OR = 2.78, 95%CI: 1.91-4.06, P < 0.01). The haplotype formed by the minor alleles of the CYP2E1*5B (C) and CYP2E1*6 (A) polymorphisms was associated with SCRC (P = 0.002). However, the CYP1A1*2A, CYP1A1*2C, EPHX1 Tyr113His and EPHX1 His139Arg polymorphisms were not associated with SCRC.

CONCLUSION

In conclusion, the results demonstrated that CYP2E1*5B and CYP2E1*6 minor alleles play a role in the development of SCRC.

Associations between CYP1A1 rs1048943 A > G and rs4646903 T > C genetic variations and colorectal cancer risk: Proof from 26 case-control studies

Cytochrome P450 1A1 (CYP1A1) enzyme is one of the most important metabolizing enzymes responsible for the metabolism of numerous xenobiotics. Numerous individual case-control studies have investigated the associations between the CYP1A1 rs1048943 A > G and rs4646903 T > C genetic variations and colorectal cancer (CRC) risk, but the conclusions were controversial. To obtain a scientific conclusion, we performed a meta-analysis based on a total of 26 publications, including 20 studies with 8665 cases and 9953 controls on rs1048943 A > G and 19 studies with 6416 cases and 7551 controls on rs4646903 T > C, respectively. The pooled analysis indicated that rs1048943 A > G was associated with an increased risk of CRC (G vs. A: OR = 1.28, 95% CI = 1.08-1.52; GG vs. AA: OR = 1.54, 95% CI = 1.25-1.91; GA vs. AA: OR = 1.26, 95% CI = 1.00-1.60; GG/GA vs. AA: OR = 1.31, 95% CI = 1.05-1.64; GG vs. GA/AA. OR = 1.56, 95% CI = 1.26-1.91). Stratification analysis showed the association between rs1048943 A > G and CRC risk was more obvious in studies with the population-based (PB) design or high quality score. The association between rs4646903 T > C and CRC risk did not reach statistical significance in the pooled analysis as well as stratification analysis. This meta-analysis demonstrated CYP1A1 rs1048943 A > G may increase the susceptibility to CRC instead of rs4646903 T > C. This conclusion suggested CYP1A1 may contribute to the pathogenesis of CRC.

CYP1A1 Ile462Val polymorphism as a risk factor in cervical cancer development in the Polish population

Background and objective

There are inconsistent data of the cytochrome P450 1A1 (CYP1A1) Ile462Val (rs1048943) single nuclear polymorphism (SNP) as a genetic susceptibility factor for cervical cancer in various populations. Moreover, little is known about the interaction of this SNP with other risk factors, including contraceptive use, postmenopausal status, parity, and tobacco smoking.

Methods

Polymerase chain reaction-restriction fragment length polymorphism was used to study the prevalence of the CYP1A1 Ile462Val SNP in women with cervical cancer (n = 456) and controls (n = 495).

Results

Logistic regression analysis adjusting for age, parity, oral contraceptive use, tobacco smoking, and menopausal status demonstrated that that the CYP1A1 Ile/Val polymorphism was not associated with an increased risk of cervical cancer in all patients. The adjusted odds ratio (OR) for patients with the Ile/Val genotype vs. Ile/Ile genotype was 1.539 (95 % confidence interval [CI] 0.932–2.541, p = 0.091). However, an increase in cervical cancer risk was seen among patients with a positive history of tobacco smoking and parity. The adjusted OR for positive history of tobacco smoking with the Ile/Val vs. Ile/Ile genotypes was 2.978 (95 % CI 1.382–6.418, p = 0.0052). The adjusted OR for parity with the Ile/Val vs. Ile/Ile genotype was 1.739 (95 % CI 1.006–3.009, p = 0.0472).

Conclusion

Our genetic study suggests that the CYP1A1 Ile462Val SNP may be a risk factor for cervical cancer among patients with a positive history of tobacco smoking and parity.

Meta-analysis of the CYP1A2 -163C>A polymorphism and lung cancer risk

Many published studies have concerned associations between the CYP1A2 -163 C>A polymorphism and risk of lung cancer, but the results have been inconsistent. Therefore, we performed a meta-analysis to obtain a more precise estimate. We searched the PubMed database up to March 1, 2013 for relevant cohort and case-control studies. Supplementary search was conducted manually by searching the references of the included studies and relevant meta-analyses. A meta-analysis was performed using RevMan 5.2 software for calculation of pooled odds ratios (ORs) and relevant 95% confidence intervals (CIs) after data extraction. Finally, seven case-control studies and one nested case-control study involving 1,675 lung cancer patients and 2,393 controls were included. The meta-analysis showed that there was no association of CYP1A2 -163 C>A polymorphism with risk of lung cancer overall [(OR=0.89, 95%CI= 0.74-1.07) for C vs. A; (OR=0.73, 95%CI= 0.50-1.07) for AA vs. CC ; (OR=0.82, 95%CI= 0.62-1.09) for AC vs. CC; (OR=0.79, 95%CI= 0.58-1.07) for (AC+AA) vs. CC; and (OR=0.87, 95%CI= 0.67-1.13) for AA vs. (CC+AC)]. Subgroup analysis indicated that there was an associationbetween CYP1A2 -163C>A polymorphism and lung cancer risk for population-based controls, a trend risk for SCCL (squamous cell carcinoma of lung) and Caucasians. These results suggested that -163 C>A polymorphism is likely to be associated with risk of lung cancer compared with population-based controls.

CYP1A1 Ile462Val polymorphism and colorectal cancer risk in Polish patients

Colorectal cancer (CRC) is an epidemiological problem of a great importance in Poland; each year approximately 14,600 new cases of the disease are diagnosed. Mortality associated with CRC reaches approximately 10,400 cases per year (according to the National Cancer Registry). The 5-year survival rate is approximately 25 %, which is one of the lowest rates in Europe. The etiology of sporadic colorectal cancer (CRC) is multifactorial and has been attributed to an interplay between both environmental and genetic risk factors. In addition, there is a general consensus that genetic factors may modulate the influence of environmental insults. Following these assumptions, we performed a study on widely described polymorphisms in xenobiotic-metabolizing enzymes and DNA repair genes which may influence individual susceptibility to cancer. We selected five candidate polymorphisms in following genes: ERCC1 Asp118Asn (rs11615), XPC i11C/A (rs2279017), XRCC3 Met241Thr (rs861539) CYP1A1 Ile462Val (rs1048943) and NAT2 A803G (rs1208) and assessed the importance of chosen SNPs on groups consisting of 478 CRC patients and 404 controls. Only CYP1A1 Ile462Val was statistically significant in CRC patients over 50 years old: OR 2.05 (1.29–3.28); p = 1.25E−02 and this association was more pronounced in the female group of CRC patients after the age of 50: OR 2.72 (1.43–5.14); p = 1.14E−02.

Genetic variations in the xenobiotic-metabolizing enzymes CYP1A1, CYP1A2, CYP2C9, CYP2C19 and susceptibility to colorectal cancer among Turkish people

Cytochrome P450 (CYP) enzymes are genetically polymorphic and play key roles in the metabolism of xenobiotics. Colorectal cancer (CRC) is one of the most common malignant tumors in Turkey as well as in the world. In this study, it was aimed both to evaluate the effects of CYP variants on the susceptibility to CRC and to predict the individual response of the Turkish people to xenobiotics metabolized by CYP enzymes. For that, we assessed the association of CYP1A1, CYP1A2, CYP2C9, and CYP2C19 polymorphisms in patients with CRC in the Turkish population through a case-control study. Distributions of the variants were determined in 104 patients with CRC and 183 healthy volunteers. As results, CYP1A1 6235T/C was significantly associated with CRC risk (odds ratio [OR]=2.53; 95% confidence interval [CI]=0.99-6.45; p=0.046). In a haplotype-based analysis, CYP1A1 haplotype C6235-A2455 might be associated with the development of CRC (OR=2.70; 95% CI=0.58-5.90; p=0.046). We believe that the findings are the first results of CYP allele distributions in the Turkish population and provide an understanding of the epidemiological studies that correlate therapeutic approaches and etiology of CRC especially in Turkish patients.

MspI and Ile462Val polymorphisms in CYP1A1 and overall cancer risk: a meta-analysis

BACKGROUND

Cytochrome P450 1A1 (CYP1A1) is a member of the CYP1 family, which is a key enzyme in the metabolism of many endogenous substrates and exogenous carcinogens. To date, many studies have examined the association between CYP1A1 MspI and Ile462Val polymorphisms and cancer risk in various populations, but their results have been conflicting rather than consistent.

METHODS

To assess this relationship more precisely, a meta-analysis based on 198 publications was performed. Odds ratios (OR) and corresponding 95% confidence intervals (CIs) were used to assess the association. The statistical heterogeneity across studies was examined with a chi-square-based Q-test.

RESULTS

Overall, a significant elevated risk of cancer was associated with CYP1A1 MspI and Ile462Val polymorphisms for all genetic models studied. Further stratified analysis by cancer types revealed that the MspI polymorphism may increase the risk of lung cancer and cervical cancer whereas the Ile462Val polymorphism may contribute to a higher risk of lung cancer, leukemia, esophageal carcinoma, and prostate cancer. In the subgroup analysis by ethnicity, obvious associations were found in the Asian population for the MspI polymorphism while an increased risk of cancer was observed in Asians and Caucasians for the Ile462Val polymorphism.

CONCLUSIONS

The results of this meta-analysis suggest that CYP1A1 MspI and Ile462Val polymorphisms contribute to increased cancer susceptibility among Asians. Additional comprehensive system analyses are required to validate this association and other related polymorphisms.

Novel insights into etiologies of leukemia: a HuGE review and meta-analysis of CYP1A1 polymorphisms and leukemia risk

We conducted a meta-analysis to investigate the association of 2 single nucleotide polymorphisms in the cytochrome P450, family 1, subfamily 1A1 gene (CYP1A1), CYP1A1*2A and CYP1A1*2C, with the risk of developing different subtypes of leukemia in adults and children. A total of 26 studies published between 1999 and 2011 were identified by searching the PubMed, EMBASE, Medline, and Web of Science databases. The odds ratios for the CYP1A1 polymorphisms and leukemia risk were calculated. The cumulative evidence in genetic associations was graded by using the Venice criteria of the Human Genome Epidemiology Network (Atlanta, Georgia). The results showed that the cumulative evidence was moderate for the association of the CYP1A1*2A variant with leukemia in Caucasians and with childhood acute lymphoid leukemia in Caucasians. In addition, there was moderate evidence that children who carry both the CYP1A1*2A variant and the glutathione S-transferase M1 null genotype have an increased risk of acute lymphoid leukemia. For the CYP1A1*2C polymorphism, the cumulative evidence of an association with leukemia risk was moderate for adults and weak for children. Logistic regression analysis demonstrated an interaction between the CYP1A1*2C polymorphism and age. This meta-analysis showed that the CYP1A1*2A and CYP1A1*2C polymorphisms were associated with an increased risk of leukemia, and that the associations might vary by ethnicity, gene-gene interactions, age, and leukemia subtype.

CYP1A1, GSTM1, GSTT1 and NQO1 polymorphisms and colorectal adenomas in Japanese men

AIM: To investigate the role of functional genetic polymorphisms of metabolic enzymes of tobacco carcinogens in the development of colorectal adenomas.

METHODS: The study subjects were 455 patients with colorectal adenomas and 1052 controls with no polyps who underwent total colonoscopy in a preretirement health examination at two Self Defense Forces hospitals. The genetic polymorphisms studied were CYP1A1*2A (rs 4646903), CYP1A1*2C (rs 1048943), GSTM1 (null or non-null genotype), GSTT1 (null or non-null genotype) and NQO1 C609T (rs 1800566). Genotypes were determined by the polymerase chain reaction (PCR)-restriction fragment length polymorphism or PCR method using genomic DNA extracted from the buffy coat. Cigarette smoking and other lifestyle factors were ascertained by a self-administered questionnaire. The associations of the polymorphisms with colorectal adenomas were examined by means of OR and 95%CI, which were derived from logistic regression analysis. Statistical adjustment was made for smoking, alcohol use, body mass index and other factors. The gene-gene interaction and effect modification of smoking were evaluated by the likelihood ratio test.

RESULTS: None of the five polymorphisms showed a significant association with colorectal adenomas, nor was the combination of GSTM1 and GSTT1. A borderline significant interaction was observed for the combination of CYP1A1*2C and NQO1 (P = 0.051). The OR associated with CYP1A1*2C was significantly lower than unity among individuals with the NQO1 609CC genotype. The adjusted OR for the combination of the CYP1A1*2C allele and NQO1 609CC genotype was 0.61 (95%CI: 0.42-0.91). Although the interaction was not statistically significant (P = 0.24), the OR for individuals carrying the CYP1A1*2C allele and GSTT1 null genotype decreased significantly compared with those who had neither CYP1A1*2C allele nor GSTT1 null genotype (adjusted OR: 0.69, 95%CI: 0.49-0.97). Smoking did not modify the associations of the individual polymorphisms with colorectal adenomas. There was no measurable effect modification of smoking even regarding the combination of the genetic polymorphisms of the phase I and phase II enzymes.

CONCLUSION: Combination of the CYP1A1*2C and NQO1 609CC genotypes was associated with a decreased risk of colorectal adenomas regardless of smoking status.

Meta-analysis of the association of CYP1A1 polymorphisms with gastric cancer susceptibility and interaction with tobacco smoking

The association of two cytochrome P4501A1 (CYP1A1) polymorphisms, m1 (T6235C transition) and m2 (A4889G transition), with gastric cancer risk is inconclusive. We conducted a meta-analysis of all available studies to evaluate the potential role of the polymorphisms and their interactions with tobacco smoking in gastric cancer susceptibility. Published literature from PubMed was retrieved by two investigators independently. Fourteen case-control studies with 2,032 gastric cancer cases and 5,099 controls were selected. A fixed effects model or a random-effects model was used to estimate the odds ratio (OR) for the CYP1A1 polymorphisms and the occurrence of gastric cancer. Significant associations between CYP1A1 m1 and m2 polymorphisms and gastric cancer susceptibility were not observed in all genetic models in the overall analyses. Subgroup analyses by ethnicity and source of controls did not reveal significant associations with gastric cancer risk. Stratification analysis by smoking status found that carriers of the heterozygous and homozygous m1 genotypes decreased the susceptibility of gastric cancer among ever-smokers (pooled OR = 0.56, 95 % CI 0.36-0.89, fixed effects). In contrast, the m2 genotypes (G/G and A/G) did not show any relevance to gastric cancer risk among the smoking population (pooled OR = 1.30, 95 % CI 0.84-2.00, fixed effects). Overall, we found that the CYP1A1 polymorphism itself, either m1 or m2, did not represent an independent genetic risk factor influencing gastric cancer. However, subgroup analyses suggest that carriers of the heterozygous and homozygous m1 genotype who are exposed to tobacco smoke have a significantly lower risk of developing gastric cancer. To explain the observed reduction of gastric cancer risk, we proposed a novel hypothesis of "observation bias". This hypothesis is also applicable to explain the combined effects of other genetic polymorphisms and environmental factors on the risk of developing cancers, and the rationality of the hypothesis needs to be further investigated.

Association between CYP1A1 polymorphism and colorectal cancer risk: a meta-analysis

Colorectal cancer is one of the most common forms of cancer and is the third leading cause of cancer-related death worldwide. Published data on the association between CYP1A1 (MspI and Ile ( 462 ) Val) polymorphisms and colorectal cancer risk are inconclusive. To address these issues, we carried out a meta-analysis of available case-control study. Online electronic searches of PubMed were performed. We identified 17 studies (6,673 colorectal cancer patients and 8,102 control subjects) that examined the association between CYP1A1 (MspI and Ile ( 462 ) Val) polymorphisms and risk of colorectal cancer. For CYP1A1 MspI polymorphism, we performed a meta-analysis from 13 studies including 5,468 cases and 6,492 controls. Overall, there was no statistically significant association between CYP1A1 MspI polymorphism and colorectal cancer susceptibility. In the subgroup analyses based on ethnicities, no statistically significant associations were observed in all genetic models. With respect to CYP1A1 Ile ( 462 ) Val polymorphism, a total of 14 studies including 6,654 cases and 7,859 controls were involved in this meta-analysis. The CYP1A1 Ile ( 462 ) Val polymorphism was associated with risk of colorectal cancer. Ethnic subgroup analyses revealed that significant associations were found in Asians and Caucasians. In summary, this meta-analysis suggests that CYP1A1 Ile ( 462 ) Val polymorphism was a low-penetrance susceptibility gene in colorectal cancer development. On the contrary, CYP1A1 MspI polymorphism does not seem capable of modifying colorectal cancer risk.

Association between polymorphism of the tumor necrosis factor alpha-308 gene promoter and colon cancer in the Chinese population

Tumor necrosis factor (TNF) is a type of cytokine that inhibits tumorigenesis. Several studies have assessed the relationship between the polymorphism of TNF-alpha 308G/A and the susceptibility to colon cancer; however, the results have been controversial. A case-control study was carried out to investigate whether TNF-alpha 308G/A gene polymorphism was associated with the risk of colon cancer in a group of 180 cases and 180 controls from Heilongjiang, China. DNA was isolated from peripheral blood, and gene polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism. Results of our study showed that colon cancer cases had a significantly higher frequency of TNF-alpha 308AA genotype (odds ratio=9.42, 95% confidence interval=1.18, 75.15; p=0.03) than controls. When stratified by the tumor location, tumor size, growth pattern, differentiation, and stage of colon cancer, no statistically significant results was observed. The present study demonstrated that TNF-alpha 308AA genotype was associated with a higher risk of colon cancer in the Chinese population. Confirmation of these findings in other populations is required.