Pectenotoxin-2 (PTX-2), which was first identified as a cytotoxic entity in marine sponges, has been reported to display significant cytotoxicity to human cancer cells where it inhibits mitotic separation and cytokinesis through the depolymerization of actin filaments. In the late stage of endoreduplication, the effects of PTX-2 on different cancer cells involves: (i) down-regulation of anti-apoptotic Bcl-2 members and IAP family proteins; (ii) up-regulation of pro-apoptotic Bax protein and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-receptor 1/receptor 2 (DR4/DR5); and (iii) mitochondrial dysfunction. In addition, PTX-2 induces apoptotic effects through suppression of the nuclear factor κB (NF-κB) signaling pathway in several cancer cells. Analysis of cell cycle regulatory proteins showed that PTX-2 increases phosphorylation of Cdc25c and decreases protein levels of Cdc2 and cyclin B1.
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