The Mutational Features of Aristolochic Acid-Induced Mouse and Human Liver Cancers

Aristolochic acid (AA) exposure has been statistically associated with human liver cancers. However, direct evidence of AA exposure-induced liver cancer is absent. This study aims to establish a direct causal relationship between AA exposure and liver cancers based on a mouse model and then explores the AA-mediated genomic alterations that could be implicated in human cancers with AA-associated mutational signature.

We subjected mice, including phosphatase and tensin homolog (Pten)-deficient ones, to aristolochic acid I (AAI) alone or a combination of AAI and CCl₄ . Significantly, AAI exposure induced mouse liver cancers, including hepatocellular carcinoma (HCC) and combined HCC and intrahepatic cholangiocarcinoma, in a dose-dependent manner. Moreover, AAI exposure also enhanced tumorigenesis in these CCl₄ -treated or Pten-deficient mice. AAI led to DNA damage and AAI-DNA adduct that could initiate liver cancers through characteristic adenine-to-thymine transversions, as indicated by comprehensive genomic analysis, which revealed recurrent mutations in Harvey rat sarcoma virus oncogene. Interestingly, an AA-associated mutational signature was mainly implicated in human liver cancers, especially from China. Moreover, we detected the AAI-DNA adduct in 25.8% (16/62) of paratumor liver tissues from randomly selected Chinese patients with HCC. Furthermore, based on phylogenetic analysis, the characteristic mutations were found in the initiating malignant clones in the AA-implicated mouse and human liver cancers where the mutations of tumor protein p53 and Janus kinase 1 were prone to be significantly enriched in the AA-affected human tumors.

This study provides evidence for AA-induced liver cancer with the featured mutational processes during malignant clonal evolution, laying a solid foundation for the prevention and diagnosis of AA-associated human cancers, especially liver cancers.