Metallothioneins protect against isoconazole nitrate-induced antitumor activity through the maintenance of cellular redox homeostasis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the predominant histological subtype of primary liver cancer with high cancer-related mortality. Despite the development of clinical advances, the prognosis of HCC patients remains very poor, and beneficial therapeutic strategies are urgently needed. Isoconazole nitrate (ISN) is an azole derivative that exhibits potent and broad-spectrum fungistatic activities for the clinical therapy of dermatomycosis. However, the role and molecular mechanism underlying the anti-neoplastic activity of ISN against HCC remain unknown. Here, we provided the first evidence that ISN inhibited the proliferation and motility of HCC cells via the generation of excessive ROS. Transcriptome sequencing and subsequent Gene Ontology (GO) enrichment analysis revealed that the detoxification of inorganic compound (metallothionein (MT) family) was most enriched in response to ISN administration. Knockdown or inhibition of MTs synergistically improved the anti-HCC activity of ISN. Moreover, we confirmed that ISN facilitated the nuclear translocation of the nuclear factor erythroid 2-related factor 2 (NRF2) protein, which in turn increased the transcription of MT family genes by directly binding to the antioxidant response elements within the MT gene promoter. Taken together, our findings revealed a novel antitumor effect of ISN on HCC and delineated an important mechanism by which NRF2-mediated transcriptional activation of MTs protects HCC cells against ISN through the maintenance of cellular redox homeostasis and mitochondrial function. ISN combined with pharmacological inhibition of MTs may be a prospective and available therapeutic approach for the clinical treatment of HCC.