The calcium channel agonist Bay K 8644 promotes the growth of human liver cancer HepG2 cells in vitro: suppression with overexpressed regucalcin


Hepatocellular carcinoma is one of the most prevalent malignant diseases and causes a third of cancer-related death. The consequences of altered calcium homeostasis in cancer cells may contribute to tumor progression. Regucalcin plays an inhibitory role in calcium signaling linked to transcription regulation. Regucalcin gene expression is downregulated in the tumor tissues of liver cancer patients, suggesting an involvement as a suppressor in hepatocarcinogenesis. We investigated whether Bay K 8644, an agonist of the L-type Ca2+ channel, promotes the growth of human liver cancer and if the effect of Bay K 8644 is suppressed by overexpressed regucalcin using the HepG2 cell model. The colony formation and growth of HepG2 cells were promoted by culturing with Bay K 8644 (0.1–10 nM). This effect was suppressed by inhibitors of signaling processes linked to cell proliferation, including PD98059 and wortmannin. Death of HepG2 cells was stimulated by Bay K 8644 with higher concentrations (25 and 100 nM). The effects of Bay K 8644 on cell growth and death were abolished by verapamil, an antagonist of calcium channel. Mechanistically, culturing with Bay K 8644 increased levels of mitogen-activated protein kinase (MAPK) and phospho-MAPK. Notably, overexpressed regucalcin suppressed Bay K 8644-promoted growth and death of HepG2 cells. Furthermore, overexpressed regucalcin prevented growth and increased death induced by thapsigargin, which induces the release of intracellular stored calcium. Thus, higher regucalcin expression suppresses calcium signaling linked to the growth of liver cancer cells, providing a novel strategy in treatment of hepatocellular carcinoma with delivery of the regucalcin gene.

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Data availability

The datasets used during the present study are available from the corresponding author upon reasonable request.


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This study was supported in part by funds provided by the University of Hawaii Cancer Center and the B.H. and Alice C. Beams Endowed Professorship in Cancer Research from the John A. Burns School of Medicine (J.W.R.), and the Foundation for Biomedical Research on Regucalcin, Japan (M.Y.).

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MY conceived the study. MY designed, and MY, TM and JWR performed the experiments. All authors discussed the findings. MY wrote the manuscript, and all authors edited the manuscript. All authors read and approved the manuscript and agree to be accountable for all aspects of the research in ensuring that the accuracy or integrity of any part of the work are appropriately investigated and resolved.

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Correspondence to Masayoshi Yamaguchi.

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Yamaguchi, M., Murata, T. & Ramos, J.W. The calcium channel agonist Bay K 8644 promotes the growth of human liver cancer HepG2 cells in vitro: suppression with overexpressed regucalcin. Mol Cell Biochem (2020).

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  • Regucalcin
  • Bay K 8644
  • Cell proliferation
  • Liver cancer
  • HepG2 cells
  • Calcium signaling
  • Thapsigargin
  • Carcinogenesis