Genetic and Functional Evaluation of the Role of FOXO1 in Antituberculosis Drug-Induced Hepatotoxicity

Abstract

Background. The accumulation of the hepatotoxic substance protoporphyrin IX (PPIX) induced by aminolevulinate synthase 1 (ALAS1) activation is one of the important mechanisms of antituberculosis drug-induced hepatotoxicity (ATDH). Forkhead box protein O1 (FOXO1) may activate ALAS1 transcription. However, little is known about their roles in ATDH; we performed a study to determine the association between polymorphisms in the two genes and ATDH susceptibility. Then, we verified this possible association by cellular functional experiments. Materials and Methods. Tag single-nucleotide polymorphisms (TagSNPs) in the two genes were genotyped in 746 tuberculosis patients. The frequencies of the alleles, genotypes, genetic models, and haplotype distribution of the variants were compared between the case and control groups. L-02 cells and HepG2 cells were incubated with the indicated concentration of isoniazid (INH) and rifampicin (RIF) for the desired times, and then the expression levels of ALAS1 and FOXO1 mRNAs and proteins were detected. HepG2 cells were transiently transfected with FOXO1 siRNA to observe the effect of changes in the FOXO1 expression on the cell survival rate and ALAS1 expression. Results. The C allele at rs2755237 and the T allele at rs4435111 in the FOXO1 gene were associated with a decreased risk of ATDH. The expression of ALAS1 in both L-02 cells and HepG2 cells was increased by the coadministration of INH/RIF (600/200 μM) for 24 h. Although FOXO1 expression was reduced slightly by the same treatment, its content in the nucleus was significantly increased. However, the cell survival rate and ALAS1 expression level were not significantly altered by the downregulation of FOXO1 in HepG2 cells. Conclusions. Variants of the rs4435111 and rs2755237 loci in the FOXO1 gene were associated with susceptibility to ATDH. Coadministration of INH/RIF promoted the transfer of FOXO1 from the cytoplasm to the nucleus, but the functional significance of its nuclear translocation requires further verification.

The role of the genetic variant FECH rs11660001 in the occurrence of anti‐tuberculosis drug‐induced liver injury

“…27 Thus, monoallelic ALAS1 mice have a complex response to physiological and drug-induced hepatic haem demand. Additionally, as shown by another Chinese study, the occurrence of abnormal porphyrin metabolism is caused by multiple regulatory disorders at the same time, 25 and polymorphisms in ALAS1 might not be sufficient to alter overall enzyme activity.…”

“…In the present study, we found four SNPs in the ALAS1 gene were not associated with AT‐DILI in all patients and in the subgroup. Another recent study from China also found that the distributions of three SNPs (rs353556, rs3852071, and rs352169) in the ALAS1 gene had no significant differences between the AT‐DILI case group and control group in either allele or genotype frequencies 25 . Although ALAS1 is the first and rate‐limiting enzyme for haem biosynthesis under normal physiological conditions, 26 two Chinese studies did not observe correlations with susceptibility to AT‐DILI.…”

Combined electronic medical records and gene polymorphism characteristics to establish an anti-tuberculosis drug-induced hepatic injury (ATDH) prediction model and evaluate the prediction value

“…PXR is an important factor in activating ALAS1 transcription ( 8 ), and the transcriptional balance of the ALAS1 gene is coordinated by a complex combination of signaling pathways. The insulin-sensitive FOXO1 pathway can synergize the transcriptional regulation of ALAS1 by PXR ( 9 , 10 ), and our previous studies have identified genetic polymorphisms in PXR and FOXO1 that correlate with ATDH susceptibility ( 6 , 11 ).…”

“…While there is a lack of specific clinical symptoms and markers for the diagnosis of ATDH, single nucleotide polymorphisms (SNPs) have been shown to have potential clinical applications as molecular markers of the disease ( 4 ). However, the results of single nucleotide SNPs do not provide a complete and systematic picture of the relevance of the signaling pathway in which they are located to ATDH ( 5 , 6 ).…”

The role of genetic polymorphism in predictive model of ATDH

“…The insulinsensitive FOXO1 pathway can synergize the transcriptional regulation of ALAS1 by PXR [7,8]. Previous studies by the group have identi ed genetic polymorphisms in PXR and FOXO1 that correlate with ATDH susceptibility [9,10].…”