Heteronemin, a Marine Sesterterpenoid-Type Metabolite, Induces Apoptosis in Prostate LNcap Cells via Oxidative and ER Stress Combined with the Inhibition of Topoisomerase II and Hsp90

Abstract

Heteronemin, a marine sesterterpenoid-type natural product, possesses diverse bioactivities, especially antitumor effect. Accumulating evidence shows that heteronemin may act as a potent anticancer agent in clinical therapy. To fully understand the antitumor mechanism of heteronemin, we further explored the precise molecular targets in prostate cancer cells. Initially, heteronemin exhibited potent cytotoxic effect against LNcap and PC3 prostate cancer cells with IC50 1.4 and 2.7 μM after 24 h, respectively. In the xenograft animal model, the tumor size was significantly suppressed to about 51.9% in the heteronemin-treated group in comparison with the control group with no significant difference in the mice body weights. In addition, the results of a cell-free system assay indicated that heteronemin could act as topoisomerase II (topo II) catalytic inhibitor through the elimination of essential enzymatic activity of topoisomerase IIα expression. We found that the use of heteronemin-triggered apoptosis by 20.1–68.3%, caused disruption of mitochondrial membrane potential (MMP) by 66.9–99.1% and promoted calcium release by 1.8-, 2.0-, and 2.1-fold compared with the control group in a dose-dependent manner, as demonstrated by annexin-V/PI, rhodamine 123 and Fluo-3 staining assays, respectively. Moreover, our findings indicated that the pretreatment of LNcap cells with an inhibitor of protein tyrosine phosphatase (PTPi) diminished growth inhibition, oxidative and Endoplasmic Reticulum (ER) stress, as well as activation of Chop/Hsp70 induced by heteronemin, suggesting PTP activation plays a crucial rule in the cytotoxic activity of heteronemin. Using molecular docking analysis, heteronemin exhibited more binding affinity to the N-terminal ATP-binding pocket of Hsp90 protein than 17-AAG, a standard Hsp90 inhibitor. Finally, heteronemin promoted autophagy and apoptosis through the inhibition of Hsp 90 and topo II as well as PTP activation in prostate cancer cells. Taken together, these multiple targets present heteronemin as an interesting candidate for its future development as an antiprostatic agent.

13-Acetoxysarcocrassolide Exhibits Cytotoxic Activity against Oral Cancer Cells through the Interruption of the Keap1/Nrf2/p62/SQSTM1 Pathway: The Need to Move Beyond Classical Concepts

“…The determination of calcium accumulation, MMP disruption, and ROS generation was reported previously [ 24 , 65 ]. Fluorescent calcium indicator (Fluo 3, 5 mM), JC-1 cationic dye (1.25 μg/mL), and the carboxy derivative of fluorescein (carboxy-H2DCFDA, 1.0 mM) were used to determine calcium accumulation, MMP disruption, and ROS generation, respectively.…”

“…Accumulating evidence shows that the disruption of calcium cellular concentration, mitochondrial membrane potential, and ROS homeostasis contribute to the induction of apoptosis [22][23][24]. Therefore, we examined whether 13-AC-induced apoptosis involves the disruption of calcium cellular concentration, mitochondrial membrane potential (MMP), and ROS homeostasis in Ca9-22 cells.…”

“…In nude mice, the xenograft animal model was established following the reported literature [24,25]. The National Laboratory Animal and Research Center (Taipei, Taiwan) was the supplier for the six-week-old male immunodeficient athymic mice.…”

Blue-Print Autophagy in 2020: A Critical Review

“…Lee et al have studied the effect of sesterterpenoid metabolite heteronemin , isolated from marine sponge Hyrtios sp. [ 113 ], in human prostate cancer LNCaP cells [ 114 ]. Apart from the anticancer activity in vitro and in vivo, which was related to oxidative stress, ER-stress, topoisomerase II and Hsp90 inhibition, the researchers observed the upregulation of cellular LC3B-II under the treatment and suggested activation of cytoprotective autophagy by the drug [ 114 ].…”

“…[ 113 ], in human prostate cancer LNCaP cells [ 114 ]. Apart from the anticancer activity in vitro and in vivo, which was related to oxidative stress, ER-stress, topoisomerase II and Hsp90 inhibition, the researchers observed the upregulation of cellular LC3B-II under the treatment and suggested activation of cytoprotective autophagy by the drug [ 114 ]. Even though the co-treatment with autophagy inhibitors 3-methyladenine and chloroquine increased the cytotoxic effects of the heteronemin in the cells, future additional experiments are essential to confirm the autophagy-inducing activity of the studied sesterterpenoid.…”