Current Drug Metabolism - Volume 26, Issue 5, 2025

CYP1B1, a crucial drug-metabolizing enzyme, metabolizes both endogenous compounds and clinical drugs. The present study investigated the effects of CYP1B1 on the proliferation, migration, apoptosis, and ferroptosis of HCC cells. It further elucidated the regulatory role of m⁶A modification particularly via the methyltransferase METTL14 in regulating CYP1B1 mRNA stability and translation efficiency.

CCK-8, colony formation, wound healing, and transwell assays were employed to assess the role of CYP1B1 in HCC cell proliferation and migration. Ferroptosis-related assays, Western blot analysis, RNA immunoprecipitation, and RNA stability assays were conducted to elucidate the underlying molecular mechanisms. The Hepatocellular Carcinoma Database (HCCDB) was utilized for gene expression analysis of CYP1B1 and METTL14.

Upregulated CYP1B1 in HCC inhibits ferroptosis and promotes cell proliferation by mediating GPX4, without significantly affecting HCC cell migration or apoptosis. METTL14-mediated m⁶A modification negatively regulates CYP1B1 expression in HCC. Specifically, METTL14 (downregulated in HCC) catalyzes m⁶A methylation of CYP1B1 mRNA, reducing its stability, while YTHDF3 binds to CYP1B1 mRNA to decrease its expression.

These findings established a functional link between drug metabolism, m⁶A epigenetics, and iron-dependent cell death in HCC, highlighting CYP1B1 and its upstream m⁶A machinery as potential targets for developing precision therapies that enhance ferroptosis sensitivity in HCC. The clinical relevance of the identified molecular mechanisms necessitates additional in-depth exploration.

CYP1B1 promotes HCC cell proliferation by regulating GPX4-mediated ferroptosis resistance, while METTL14-mediated m⁶A modification serves as a key negative regulatory mechanism for CYP1B1. Targeting CYP1B1 as a therapeutic strategy holds substantial promise for future drug development in HCC.

Hepatic lipid accumulation (steatosis) is an early indicator of non-alcoholic fatty liver disease (NAFLD), preceding fibrosis and cirrhosis. Understanding its effects on drug-metabolizing enzymes (DMEs) and transporters is crucial for assessing potential alterations in drug disposition among NAFLD patients. This study aimed to replicate steatosis in an in vitro HepaRG cell model and analyze its impact on DMEs and transporters.

Differentiated HepaRG cells were treated with a mixture of saturated (palmitate) and unsaturated (oleate) fatty acids (in a 1:2 ratio at 0.5 mM), complexed with BSA for 72 hours to induce lipid accumulation. Confirmation of steatosis was performed using Oil Red O staining and triglyceride (TG) quantification, while cell viability was assessed via the WST-1 assay. RNA sequencing and SWATH-MS proteomic analysis were employed to identify differentially expressed transcripts and proteins in lipid-loaded cells compared to controls.

Lipid loading resulted in a ~6-fold increase in TG concentration without compromising cell viability. Transcriptomic analysis identified 393 differentially expressed transcripts (89 upregulated, 304 downregulated), while proteomic analysis detected 165 differentially expressed proteins (127 upregulated, 38 downregulated). Notably, key mRNA transcripts related to transcription factors (NR1I2, HNF4α), phase 1 DMEs (CYP1A2, 2B6, 2C8, 2C9, 2C19, 3A4), phase 2 DMEs (UGT1A6, 2B7, SULT2A1, 1E1), and transporters (ABCC11, ABCG5, SLCO2B1, SLC10A1) exhibited significant downregulation.

The observed alterations in DMEs and transporters suggest a potential shift in drug metabolism pathways under NAFLD conditions. Downregulation of transcription factors and metabolic enzymes could impact drug efficacy and toxicity, necessitating further research into the pharmacokinetic implications.

The in vitro hepatic steatosis model demonstrated significant changes in the expression of clinically relevant DMEs and transporters. These findings highlight the importance of considering NAFLD-induced metabolic alterations when assessing drug disposition in affected patients