Hepatocellular carcinoma (HCC) is a highly fatal disease recognized as a growing global health crisis. Traditional Chinese herbal medicines have been used to treat patients with cancer for many years in China. This study investigated the effects of licochalcone B (LCB), a flavonoid compound isolated from the root of Glycyrrhiza uralensis Fisch., on cell proliferation, DNA damage and TNF-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis in HCC cells. Our results showed that LCB inhibited cell proliferation and induced DNA damage, cell cycle arrest and apoptosis. Treatment with LCB significantly inhibited the Akt/mTOR pathway and activated endoplasmic reticulum (ER) stress and mitogen-activated protein kinase (MAPK) signaling pathway. Moreover, combined treatment with LCB and TRAIL yielded evident enhancements in the viability reduction and apoptosis. LCB upregulated death receptor 4 (DR4) and death receptor 5 (DR5) protein in a concentration- and time-dependent manner. The knockdown of DR5 significantly suppressed TRAIL-induced cleavage of PARP, which was enhanced by LCB. Treatment with an extracellular-regulated kinase (ERK) inhibitor (PD98059) or c-Jun N-terminal kinase (JNK) inhibitor (SP600125) markedly reduced the LCB-induced upregulation of DR5 expression and attenuated LCB-mediated TRAIL sensitization. In summary, LCB exhibits cytotoxic activity through modulation of the Akt/mTOR, ER stress and MAPK pathways in HCC cells and effectively enhances TRAIL sensitivity through the upregulation of DR5 expression in ERK- and JNK-dependent manner. Combination therapy with LCB and TRAIL may be an alternative treatment strategy for HCC.
Keywords: Apoptosis; DR5; ERK; JNK; Licochalcone B; TRAIL.
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