Long Noncoding RNAs Hepatocyte Nuclear Factor 4A Antisense RNA 1 and Hepatocyte Nuclear Factor 1A Antisense RNA 1 are Involved in Ritonavir‐induced Cytotoxicity in Hepatoma Cells

Abstract

Ritonavir (RTV), a pharmacoenhancer used in anti‐HIV regimens, can induce liver damage. RTV is mainly metabolized by cytochrome P450 3A4 (CYP3A4) in the liver. HNF4A antisense RNA 1 (HNF4A‐AS1) and HNF1A antisense RNA 1 (HNF1A‐AS1) are long noncoding RNAs (lncRNAs) that regulate the expression of pregnane X receptor (PXR) and CYP3A4. This study investigated the role and molecular mechanisms of HNF4A‐AS1 and HNF1A‐AS1 in RTV‐induced hepatotoxicity. Small hairpin RNAs were used to knock down HNF4A‐AS1 and HNF1A‐AS1 in Huh7 and HepG2 cells. Lactate dehydrogenase and reactive oxygen species assays were performed to assess RTV‐induced hepatotoxicity. Chromatin immunoprecipitation qPCR was used to detect PXR enrichment and histone modifications in the CYP3A4 promoter. HNF4A‐AS1 knockdown increased PXR and CYP3A4 expression and exacerbated RTV‐induced cytotoxicity, whereas HNF1A‐AS1 knockdown generated the opposite phenotype. Mechanistically, enrichment of PXR and trimethylation of histone 3 lysine 4 (H3K4me3) in the CYP3A4 promoter was increased, and trimethylation of histone 3 lysine 27 (H3K27me3) was decreased after HNF4A‐AS1 knockdown. However, PXR and H3K4me3 enrichment decreased after HNF1A‐AS1 knockdown. Alterations in RTV‐induced hepatotoxicity caused by decreasing HNF4A‐AS1 or HNF1A‐AS1 were reversed by knockdown or overexpression of PXR. Increased susceptibility to RTV‐induced liver injury caused by the PXR activator rifampicin was attenuated by HNF4A‐AS1 overexpression or HNF1A‐AS1 knockdown. Taken together, these results revealed that HNF4A‐AS1 and HNF1A‐AS1 modulated RTV‐induced hepatotoxicity by regulating CYP3A4 expression, primarily by affecting the binding of PXR and histone modification status in the CYP3A4 promoter.

HNF4A-AS1 inhibits the progression of hepatocellular carcinoma by promoting the ubiquitin-modulated degradation of PCBP2 and suppressing the stability of ARG2 mRNA

“…HNF4A-AS1, the antisense strand of HNF4A, is highly expressed in liver tissue. It plays a regulatory role in the expression of CYP3A4 by in uencing the accumulation of PXR in the CYP3A4 promoter and modifying histones 13 . This regulation leads to the inhibition of P450 expression in the liver, preventing ritonavir-induced hepatotoxicity 14 .…”