Experimental Therapy of Hepatoma with Artemisinin and Its Derivatives: In vitro and In vivo Activity, Chemosensitization, and Mechanisms of Action

Abstract

Purpose: ART and its derivatives, clinically used antimalarial agents, have recently shown antitumor activities. However, the mechanisms underlying these activities remain unclear. This study was designed to determine their antitumor efficacy and underlying mechanisms of action in human hepatoma cells. Experimental Design: The in vitro cytotoxicities of ART, DHA, artemether, and artesunate were compared in human hepatoma cells, HepG2 (p53 wild-type), Huh-7 and BEL-7404 (p53 mutant), and Hep3B (p53 null), and a normal human liver cell line, 7702. Based on their activity and specificity, ART and DHA were further investigated for their in vitro and in vivo antitumor effects and their effects on the protein expression of genes associated with cell proliferation and apoptosis. Results: ART and DHA exerted the greatest cytotoxicity to hepatoma cells but significantly lower cytotoxicity to normal liver cells. The compounds inhibited cell proliferation, induced G 1 -phase arrest, decreased the levels of cyclin D1, cyclin E, cyclin-dependent kinase 2, cyclindependent kinase 4, and E2F1, and increased the levels of Cip1/p21 and Kip1/p27. They induced apoptosis, activated caspase-3, increased the Bax/Bcl-2 ratio and poly(ADP-ribose) polymerase, and down-regulated MDM2. In mice bearing HepG2 and Hep3B xenograft tumors, ART and DHA inhibited tumor growth and modulated tumor gene expression consistent with in vitro observations. DHA increased the efficacy of the chemotherapeutic agent gemcitabine. Conclusions: ART and DHA have significant anticancer effects against human hepatoma cells, regardless of p53 status, with minimal effects on normal cells, indicating that they are promising therapeutics for human hepatoma used alone or in combination with other therapies.

Dihydroartemisinin Induces Apoptosis by a Bak-Dependent Intrinsic Pathway

“…These findings corroborate recent in vitro data on increased efficacy of DHA in Molt-4 and glioma cells when combined with irradiation (48). Further reports from other laboratories showed beneficial effects of DHA on the cytotoxic action of sodium butyrate (49), doxorubicin (13), gemcitabine (50), temozolomide (51), carboplatin (13,38), and cyclophosphamide (52), respectively. Thus, a sensitizing effect of DHA can even be achieved in combination with other stimuli of the intrinsic apoptosis pathway.…”

In vitro study of the anti-cancer effects of artemisone alone or in combination with other chemotherapeutic agents

“…Changes in the cell cycle were observed after treatment with the agents; specifically, cell cycle arrest as reported previously [20,[34][35][36]. Our results showed that the compounds generally induced a simultaneous arrest at all phases of the cell cycle.…”

“…Studies have identified several potential mechanisms by which the artemisinins can act against cancer cells. They have been shown to be antiproliferative through action on key cell cycle regulatory proteins such as p21 waf1cip1 and cyclin D1 [20]; pro-apoptotic by manipulating the Bax:Bcl-2 rheostat [21,22]; antiangiogenic by targeting vascular endothelial growth factor [23,24]; and anti-migratory through their effects on αVβ3 integrins [25]. The multi-modal character of these antimalarial drugs, allied to their low host toxicity even at high doses [26,27], reinforces the priority for them to be developed as a novel anti-cancer agents.…”

“…Interestingly, ART and ATM had no effect on the p53 mutant cell line PANC-1. It maybe that an active form 15 of p53 is required for the cytostatic mechanism of ATM, however, other studies have shown that the artemisinins can exert their effects on p53 mutant [20] and p53 knockout [34] cell lines. More importantly, the DNA damaging qualities of this class of agent has yet to be fully elucidated, with a wealth of data highlighting both genotoxic and non-genotoxic effects [39].…”

Immunochemical Analysis of the Antimalarial Drugs Artemisinin and Artesunate

“…Recent studies have shed light on the mechanisms underlying the anticancer activities of AM, and synthetic approaches to preparing AM derivatives that display better efficacy and tolerability profiles have been conducted by several groups [13][14][15][16][17][18][19][20]. The expanded medicinal applications of AM-related compounds may increase the demand for AM in the future.…”