Plancitoxin I from the venom of crown-of-thorns starfish (Acanthaster planci) induces oxidative and endoplasmic reticulum stress associated cytotoxicity in A375.S2 cells

The crown-of-thorns starfish Acanthaster planci is a venomous starfish whose venom provokes strong cytotoxicity. In the present study, the purified cytotoxic toxin of A. planci venom (CAV) was identified as plancitoxin I protein by mass spectrum analyses. This study aims to investigate the molecular mechanism underlying the cytotoxicity function of plancitoxin I by focusing on the oxidative stress, mitochondrial dysfunction and endoplasmic reticulum (ER) stress pathway in human melanoma A375.S2 cells. The results indicated that after being treated with CAV toxin, A375.S2 cells significantly decreased viability in a dose-dependent manner. The CAV was found to reduce the cellular antioxidant enzymes such as SOD and CAT, and there was a significant decrease in total thiol level and mtDNA integrity, and it enhanced the lipid peroxidation. In addition, CAV increased cytosolic Ca(2+) concentration, and enhanced the expression of the ER molecular chaperones GRP78 and CHOP in a dose-dependent manner. CAV significantly elevated the activity of caspase-3, -8 and -9, and reduced the ratio of Bcl-2/Bax. The cells exhibited apoptosis were determined by using propidium iodide (PI) staining of DNA fragmentation (sub-G1 peak). In summary, the results demonstrated that plancitoxin I inhibits the proliferation of A375.S2 cells through induction of oxidative stress, mitochondrial dysfunction and ER stress associated apoptosis.

Antioxidative and anticancer activities of various ethanolic extract fractions from crown-of-thorns starfish (Acanthaster planci)

Many studies currently researching marine invertebrates to determine the therapeutic potential of their bioactive materials have been showing very promising results. The crown-of-thorns starfish Acanthaster planci, an Echinodermata of the class Asteroidea, is infamous as the unique venomous starfish and as a destroyer of coral reefs. Starfish possesses many useful pharmacological and biological characteristics. In this study, A. planci was extracted with 70% ethanol and lyophilized to obtain an ethanol fraction. The ethanol fraction was dissolved with water and defatted with petroleum ether to obtain a non-polar fraction. The residual solution was successively partitioned with ethylacetate and butanol to obtain an ethylacetate fraction and butanol fraction, respectively. Four fractions were used to examine the antioxidant and anticancer properties. The ethanol fraction of A. planci contained the highest antioxidant effects such as ABTS, DPPH, Fe(2+) chelating activity and reducing power when compared with four fractions. Among the four fractions, the butanol fraction was especially shown to inhibit human malignant melanoma A375.S2 cells' proliferation, which is involved in the apoptotic progression. This fraction could induce apoptosis and even necrosis in A375.S2 cells as evidenced by double staining with an Annexin V-FITC and PI assay and DNA fragmentation analysis. These results indicated that the starfish A. planci is a good resource for obtaining the biologically active substances for antioxidant and anticancer effects.