Combination of WIN55,212-2 and auranofin synergistically suppresses
human hepatocellular carcinoma HepG2 cell proliferation and
tumorigenesis and induces cellular senescence and apoptosis via Wnt/
β-catenin signaling
Abstract
WIN55,212-2(WIN) is a cannabinoid receptor agonist. We previously found
that WIN may induce cell cycle arrest and inhibit the proliferation and
migration of hepatocellular carcinoma (HCC) BEL7402 cells. Auranofin
(AUR) is an FDA-approved drug against rheumatoid arthritis that is
currently enrolled in clinical trials as an anti-tumor agent. However,
the precise functions of WIN and/or AUR on HCC carcinogenesis remain
unexplored. In the present study, we aimed to study the synergistic
antitumor effects and the associated underlying mechanisms of AUR/WIN
combination therapy on HCC. We showed that WIN/AUR cotreatment
synergistically suppressed HepG2 cell proliferation, migration and
invasion. Western blot assay found that WIN/AUR cotreatment
synergistically downregulated the expression of Bcl-2, cyclin D1,
β-catenin, c-myc, and MMP-9 and increased the expression of Bip and
ATF4, further activating Caspase3, Caspase 8, Caspase 9 and PARP
cleavage. Cotreatment of AUR/WIN also arrested cell cycle at the G1
phase and induced senescence and apoptosis, evidenced by an increase in
the number of SA-β-gal + senescent cells and loss of
mitochondrial membrane potential (MMP) in AUR/WIN-cotreated cells.
Luciferase reporter assay found that the activation of Wnt/β-catenin
signaling was significantly suppressed upon WIN/AUR cotreatment in
comparison with other groups. Moreover, WIN/AUR cotreatment
synergistically inhibited tumor growth in subcutaneous xenograft mice
models. In conclusion, our results demonstrated WIN/AUR-mediated
apoptosis and suppressive effects on cell growth, migration and invasion
were associated with Bcl-2 downregulation, endoplasmic reticulum (ER)
stress and caspase activation, leading to downregulation of
Wnt/β-catenin signaling. Therefore, WIN/AUR cotreatment may present
promising combination therapy for the treatment of HCC.