Apoptosis inducing capacity of Holothuria arenicola in CT26 colon carcinoma cells in vitro and in vivo

OBJECTIVES Sea cucumber is one of the classes of echinoderms, which is considered as a health marine product and possess various biological characteristics with therapeutic application. The present investigation attempted to evaluate the potential of anti-cancer Persian Gulf sea cucumber species Holothuria arenicola (H. arenicola) aqueous extract on mice colon carcinoma cells in vitro and in vivo. MATERIALS AND METHODS The CT26 carcinoma cells were treated with various concentrations of extract in 24 and 48 hr, and then its anti-proliferative effect was measured by MTT assay and morphological observations. The apoptotic effect was examined by fluorescence microscopy (DNA fragmentation assay), Flow cytometry, caspase-3 and -9 colorimetric assays. The in vivo anti-tumor efficacy of sea cucumber extract on CT26 tumor cells transplanted in BALB/c mice was also investigated. RESULTS The results showed that the water extract of sea cucumber revealed remarkable anti-proliferative effect on CT26 tumor cells with IC50= 31 µg/ml with recruitment of intrinsic apoptotic pathway in vitro. In addition, the colon tumor volume in treated groups remarkably reduced in homozygous mice. Histopathological examination elucidated that sea cucumber extract attenuated tumor size and volume along with apoptosis characteristics. Moreover, RT-PCR analysis revealed that sea cucumber extract induced intrinsic apoptosis in vivo through suppression of Bcl-2 expression. CONCLUSION Our data confirmed this notion that sea cucumber administrates anti-cancer effect that can be used as complementary in preclinical experiments, so further characterization are recommended for detection sea cucumber metabolites and clinical application.