Abstract
PURPOSE: We aimed to elucidate the applicability of tumor organoids for inherent drug resistance of primary liver cancer (PLC) and mechanisms of acquired drug resistance. METHODS: PLC tissues were used to establish organoids, organoid-derived xenograft (ODX) and patient-derived xenograft (PDX) models. Acquired drug resistance was induced in hepatocellular carcinoma (HCC) organoids. Gene expression profiling was performed by RNA-sequencing. RESULTS: Fifty-two organoids were established from 153 PLC patients. Compared with establishing PDX models, establishing organoids of HCC showed a trend toward a higher success rate (29.0% vs. 23.7%) and took less time (13.0 ± 4.7 vs. 25.1 ± 5.4 days, p = 2.28 × 10(-13)). Larger tumors, vascular invasion, higher serum AFP levels, advanced stages and upregulation of stemness- and proliferation-related genes were significantly associated with the successful establishment of HCC organoids and PDX. Organoids and ODX recapitulated PLC histopathological features, but were enriched in more aggressive cell types. PLC organoids were mostly resistant to lenvatinib in vitro but sensitive to lenvatinib in ODX models. Stemness- and epithelial-mesenchymal transition (EMT)-related gene sets were found to be upregulated, whereas liver development- and liver specific molecule-related gene sets were downregulated in acquired sorafenib-resistant organoids. Targeting the mTOR signaling pathway was effective in treating acquired sorafenib-resistant HCC organoids, possibly via inducing phosphorylated S6 kinase. Genes upregulated in acquired sorafenib-resistant HCC organoids were associated with an unfavorable prognosis. CONCLUSIONS: HCC organoids perform better than PDX for drug screening. Acquired sorafenib resistance in organoids promotes HCC aggressiveness via facilitating stemness, retro-differentiation and EMT. Phosphorylated S6 kinase may be predictive for drug resistance in HCC.