The GSTP1 Ile105Val polymorphism is not associated with susceptibility to colorectal cancer

Allele and genotype frequencies of CYP3A4, CYP3A5, CYP3A7, and GSTP1 gene polymorphisms among mainland Tibetan, Mongolian, Uyghur, and Han Chinese populations

Over 50% prescribed drugs are metabolised by cytochrome P450 3A (CYP3A) and glutathione S-transferase pi (GSTP1) adds a glutathione to the oxidative products by CYP3A, which increases the hydrophilic property of metabolites and facilitates the excretion. Single nucleotide polymorphisms (SNPs) of CYP3A and GSTP1 show a diverse allele and genotype frequencies distribution among the world populations. The present study aimed to investigate the genotype and allele frequency distribution patterns of CYP3A4, CYP3A5, CYP3A7 and GSTP1 polymorphisms among healthy participants in mainland Tibetan, Mongolian, Uyghur, and Han Chinese populations. Blood samples were collected from 842 unrelated healthy subjects (323 Tibetan, 134 Mongolian, 162 Uyghur, and 223 Han) for genotyping analysis. Variant allele frequencies of CYP3A4 rs2242480, CYP3A5 rs776746, CYP3A7 rs2257401, and GSTP1 Ile105Val were observed in Han (0.253, 0.686, 0.312 and 0.188), Tibetan (0.186, 0.819, 0.192 and 0.173), Mongolian (0.198, 0.784, 0.228 and 0.235) and Uyghur (0.179, 0.858, 0.182 and 0.250) respectively. The allele frequency of CYP3A7*1C in Uyghur (0.019) was higher than that in Tibetan (0.002, p < 0.01). There was a strong linkage disequilibrium between CYP3A4 rs2242480, CYP3A5 rs776746, and CYP3A7 rs2257401 among the four ethnic groups. The results might be useful for the precise medication in the Chinese populations.

Risk of Colorectal Carcinoma May Predispose to the Genetic Variants of the GST, CYP450, and TP53 Genes Among Nonsmokers in the Saudi Community

PURPOSE

Colorectal carcinoma (CRC) represents a considerable public health burden in Saudi Arabia. Several candidate genes and genetic variants have been associated with morbidity and mortality among patients with CRC. We explored whether allelic variants of the GSTM1, GSTT1, CYP450 (rs4646903 and rs1048943), and TP53 (rs1042522) genes predisposed nonsmoking Saudi individuals to increased risk for CRC.

PATIENTS AND METHODS

DNA from buccal cells of 158 participants (80 with CRC and 78 healthy controls) were analyzed for five SNPs using conventional PCR and TaqMan genotyping assays. The SNPStats software was utilized to choose the best interactive inheritance mode for selected SNPs (https://www.snpstats.net).

RESULTS

The mean age of diagnosis was 62.4±13.5 years (range, 40-83 years), with those aged 71-80 years and those aged 40-50 years accounting for the most diagnoses (35.7% and 28.6% of diagnosis, respectively). The GSTM1 and TP53 rs1042522 SNPs were associated with CRC (OR= 3.7; P< 0.0001, and OR= 1.6; P= 0.033, respectively). A plausible contribution to CRC was observed for the GSTM1 and TP53 rs1042522 SNPs (x ² _Yates= 14.7; P= 0.00013, and x ² _Yates= 11.2; P= 0.0008, respectively), while the GSTT1 null variant did not affect risk. Heterozygosity in the CYP450 (rs4646903 and rs1048943 SNPs) was associated with a significant risk for CRC. The GSTM1/GSTT1 and CYP450 rs4646903/rs1048943 SNP pairs were in linkage disequilibrium, and the associations were statistically significant (P= 0.01 and P= 4.6x10^‒7, respectively).

CONCLUSION

The GSTM1 and TP53 rs1042522 variants can increase the development of CRC in Saudi nonsmokers. Even the presence of one copy of a variant allele in the CYP1A1 gene can predispose CRC risk. Additional studies should also examine other SNP combinations with lifestyle factors that may help prevent, rather than facilitate, colorectal tumorigenesis.

GSTM1 and GSTP1 Genetic Polymorphisms and Their Associations With Acute Lymphoblastic Leukemia Susceptibility in a Jordanian Population

The genetic variations between different individuals in the xenobiotic detoxifying enzyme activity were shown to change susceptibility to acute lymphoblastic leukemia (ALL). The current study aimed to assess the association of GSTM1 and GSTP1 genetic polymorphisms with the susceptibility of ALL. This case-control study (N=264) involved 88 Jordanian ALL children and 176 healthy controls from an ethnically homogenous Jordanian children population. The polymerase chain reaction assay was used to genotype GSTM1 (null/present) and the polymerase chain reaction-restriction fragment length polymorphism technique was also applied to detect the genetic polymorphisms of GSTP1 (Ile105Val) at the rs1695 position. The biallelic analysis revealed that there was no association between GSTM1 double-null genotype and ALL (P=0.57). However, there was a strong association between GSTP1 (Ile105Val) polymorphism genotypes and alleles within GSTP1 gene and ALL (P=0.00049 and 0.000044, respectively). A combination between GSTM1 double-null genotype and rs1695 also showed an association with ALL (P=0.042). This study showed that the rs1695 single nucleotide polymorphism within the GSTP1 gene is strongly implicated in ALL among Jordanian children with ALL. These results indicate that genetic variants of GSTP1 gene influence the risk of developing ALL in the Jordanian children of Arab ancestry.

A systemic review of glutathione S-transferase P1 Ile105Val polymorphism and colorectal cancer risk

OBJECTIVES

To investigate the correlation between glutathione S-transferase P1 (GSTP1) Ile105Val polymorphism and colorectal cancer (CRC) risk.

METHODS

Studies were identified to investigate the association between GSTP1 Ile105Val polymorphism and CRC risk. Systematic computerized searches of the PubMed, Chinese National Knowledge Infrastructure, WANFANG and SinoMed were performed. Summary odds ratios (OR) and 95% confidence intervals (95% CI) were used to measure GSTP1 Ile105Val polymorphisms and CRC risk.

RESULTS

A total of 23 retrospective studies were included in the meta-analysis. During all studies including 6,981 cases and 8,977 controls, sample sizes ranged from 146 to 2,144. Overall, the pooled results revealed that Ile105Val polymorphism was not associated with CRC risk and confused results were found in subgroup analyses. Further meta-analyses were conducted after excluding low-quality studies. GSTP1 Ile105Val is associated with increased risk of CRC limited in studies with matched control. There was no significant heterogeneity in all genetic comparisons, but heterogeneity existed in subgroup analyses of heterozygous and dominant comparisons. The meta-regression analyses indicated that matched controls were the significant factor influencing between-study heterogeneity in all possible influential factors including published year, ethnicity, source of control, sample size, Hardy-Weinberg equilibrium (HWE) in control and matched controls. Sensitivity analysis revealed the pooled ORs were not changed before and after removal of each single study in all genetic comparisons, indicating the robustness of the results.

CONCLUSIONS

GSTP1 Ile105Val might be associated with increased risk of CRC. However, more high-quality case-control studies should be performed to confirm the authenticity of our conclusion.

GST gene polymorphisms and the risk of colorectal cancer development

Increasingly often, molecular studies of colorectal cancer focus on low penetrance genes. Among the factors potentially modifying the risk of contracting colorectal cancer is the glutathione S-transferase (GST) gene family, encoding enzymes of the glutathione transferase type. Proteins of the GST family (glutathione S-transferases) are enzymes detoxifying a wide range of hazardous substances, such as reactive oxygen species (ROS) or xenobionts. Thus, their role, among other things, is the protection of DNA against oxidative damage, which may lead to mutations, and in consequence, favour carcinogenesis. GST gene polymorphisms may affect the functioning of the encoded enzymes, exerting an effect on the level of DNA damage, and therefore may have an indirect influence on the risk of the development of cancer. At present, there are many studies available concerning GST gene polymorphisms as factors modulating the risk of developing cancer, including colorectal cancer.