Abstract
Hepatocellular carcinoma (HCC) is one of the major causes of cancer-related death worldwide. High Akt activation and aberrant β-catenin expression contribute to HCC cell proliferation, stem cell generation, and metastasis. Several signaling pathway-specific inhibitors are in clinical trials and display different efficacies against HCC. In this study, we observed that a β-catenin inhibitor (FH535) displays antiproliferative effect on transformed human hepatocytes (THH). A combination treatment of these cells with FH535 and Akt inhibitor (AZD5363) exerted a stronger effect on cell death. Treatment of THH with AZD5363 and FH535 inhibited cell-cycle progression, enhanced autophagy marker protein expression, and autophagy-associated death, while FH535 treatment alone induced apoptosis. The use of chloroquine or z-VAD further verified these observations. Autophagy flux was evident from lowering marker proteins LAMP2, LAPTM4B, and autophagic protein expression by confocal microscopy using mCherry-EGFP-LC3 reporter construct. A combination treatment with AZD5363 and FH535 enhanced p53 expression, by modulating MDM2 activation; however, AZD5363 treatment alone restricted p53 to the nucleus by inhibiting dynamin-related protein activation. Nuclear p53 plays a crucial role for activation of autophagy by regulating the AMPK–mTOR-ULK1 pathway. Hep3B cells with null p53 did not modulate autophagy-dependent death from combination treatment. Together, our results strongly suggested that a combination treatment of Akt and β-catenin inhibitors exhibits efficient therapeutic potential for HCC.
Highlights
Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and occurs most often in people with chronic liver diseases, such as metabolic disorder, alcohol consumption, and cirrhosis caused by hepatitis B virus (HBV) or hepatitis C virus (HCV) infection
We have shown that HCV-infected primary human hepatocytes exhibit high expression of β-catenin9. β-catenin inhibitors may be applicable for the prevention of organ fibrosis, second-line HCC prevention, and treating β-catenin-driven cancer
Our results suggested a high efficacy of FH535, displaying a better inhibitory effect on transformed human hepatocytes (THH) growth at 72 h when compared with AZD5363 (Fig. 1a, b) or when tested with the other inhibitors (Lin[28] inhibitor—C1632, Raf kinase inhibitor—sorafenib, mTOR inhibitor—AZD8055, and Stat[3] inhibitor—Stattic—data not shown)
Summary
HCC is the most common type of primary liver cancer and occurs most often in people with chronic liver diseases, such as metabolic disorder, alcohol consumption, and cirrhosis caused by hepatitis B virus (HBV) or hepatitis C virus (HCV) infection. Patra et al Cell Death and Disease (2020)11:540. A wide range of solid and hematological malignancies show dysregulated PI3K/Akt/mTOR signaling due to mutations in multiple signaling components. Deregulation of the PI3K/Akt/mTOR pathway is increasingly implicated in HCC4. A serine/threonine-specific protein kinase, plays a key role in multiple cellular processes, including gene transcription and cell proliferation. AZD5363 is an Akt protein kinase inhibitor that binds to and inhibits all Akt isoforms[5]. Inhibition of Akt prevents the phosphorylation of AKT substrates that mediate cellular processes, such as cell division, apoptosis, glucose, and fatty acid metabolism. Targeting Akt is used as a therapy for a variety of human cancers
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