Genetic polymorphism of Arg213His variant in the SULT1A1 gene is associated with reduced susceptibility to lung cancer in North Indian population

Synergistic polymorphic interactions of phase II metabolizing genes and their association toward lung cancer susceptibility in North Indians

Lung cancer is a multifactorial carcinoma with diverse heterogeneity. Genetic variations in drug-metabolizing enzymes may lead to defective detoxification and clearance of carcinogenic compounds. The high-order gene-gene interaction has been carried out between different genotypes of Phase II detoxification genes (NQO1, SULT1A1, NAT2, and EPHX1). Our results depict the genetic combination of SULT1A1 R213H with NAT2 × 5B L161L, SULT1A1 R213H with NAT2 × 5C K268R, EPHX1 H139R and NAT2 × 5B L161L exhibit a protective effect towards lung cancer risk. Further, the triple combinations of NQO1 P187S, EPHX1 Y113H, and EPHX1 H139R; NQO1 P187S, EPHX1 Y113H, and NAT2 × 6 R197Q; NQO1 P187S, EPHX1 Y113H, and NAT2 × 7 G286E; SULT1A1 R213H, EPHX1 H139R, and NAT2 × 7 G286E suggested a two-fold increased risk of lung cancer for subjects. Genetic polymorphisms of phase II detoxifying genes (NAT2, NQO1, EPHX1, SULT1A1) are prognostic markers for lung cancer.

Aha1 Is an Autonomous Chaperone for SULT1A1

The cochaperone Aha1 activates HSP90 ATPase to promote the folding of its client proteins; however, very few client proteins of Aha1 are known. With the use of an ascorbate peroxidase (APEX)-based proximity labeling method, we identified SULT1A1 as a proximity protein of HSP90 that is modulated by genetic depletion of Aha1. Immunoprecipitation followed by Western blot analysis showed the interaction of SULT1A1 with Aha1, but not HSP90. We also observed a reduced level of SULT1A1 protein upon genetic depletion of Aha1 but not upon pharmacological inhibition of HSP90, suggesting that the SULT1A1 protein level is regulated by Aha1 alone. Maturation-dependent interaction assay results showed that Aha1, but not HSP90, binds preferentially to newly synthesized SULT1A1. Reconstitution of Aha1-depleted cells with wild-type Aha1 and its E67K mutant, which is deficient in interacting with HSP90, restored SULT1A1 protein to the same level. Nonetheless, complementation of Aha1-depleted cells with an Aha1 mutant lacking the first 20 amino acids, which disrupts its autonomous chaperone function, was unable to rescue the SULT1A1 protein level. Together, our study revealed, for the first time, Aha1 as an autonomous chaperone in regulating SULT1A1. SULT1A1 is a phase-II metabolic enzyme, where it adds sulfate groups to hydroxyl functionalities in endogenous hormones and xenobiotic chemicals to improve their solubilities and promote their excretion. Thus, our work suggests the role of Aha1 cochaperone in modulating the detoxification of endogenous and environmental chemicals.

Predictive role of polymorphic variants of phase II drug metabolising enzyme in modulating toxicity in North Indian lung cancer patients undergoing chemotherapy

Genetic polymorphism of drug-metabolizing enzymes such as NQO1, SULT1A1, EPHX1, and NAT2 alters its activity which hampers the detoxification and disposal of chemotherapeutic compounds. Thus, in the present study, we have comprehensively investigated the associations between SNPs of the Phase II detoxifying genes and its relationship towards platinum-induced toxicity of lung cancer patients.A total of 273 samples were enrolled in this study and polymorphisms of gene NQO1 (609C > T), SULT1A1 (Arg²¹³ His), EPHX1 (Tyr¹¹³His, His¹³⁹Arg), and NAT2 (481C > T, 803A > G, 590 G > A, 857 G > A) were evaluated in our study for their associated adverse events caused due to the administration of platinum-based chemotherapy to the lung cancer patients.For NQO1 609C > T polymorphism, the TT genotype showed reduced risk of constipation (OR =0.10, p=0.04) and anorexia (OR =0.15, p=0.03). For SULT1A1 Arg²¹³His, heterozygous genotype (Arg/His) (AOR =0.38, p=0.006) and combined genotype (Arg/His + His/His) were not associated with increased risk of nephrotoxicity (AOR =0.38, p= 0.004). For NAT2, heterozygous (NAT2*4/*6) and combined genotypes (NAT2*4/*4 + *4/*6) for NAT2*6 polymorphism exhibit 2.4 folds (p=0.005), and two-folds (p=0.01) increased risk of hematological toxicity. The heterozygous (AOR =0.45, p=0.004) and variant genotype (AOR =0.39, p=0.02) for NAT2*5C had decreased risk for hematological toxicity. The heterozygous genotype for NAT2*7 polymorphism showed two-fold increased risk for developing thrombocytopenia.This study provides association of NAT2 polymorphic variants in predicting haematological toxicity.