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

Abstract

<strong><em>Objective(s):</em></strong>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<em> Holothuria arenicola (H. arenicola) </em>aqueous extract on mice colon carcinoma cells <em>in vitro</em> and <em>in vivo</em>. <strong><em>Materials and Methods:</em></strong> 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 <em>in vivo</em> anti-tumor efficacy of sea cucumber extract on CT26 tumor cells transplanted in BALB/c mice was also investigated. <strong><em>Results: </em></strong>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 <em>in vitro</em>. 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 <em>in vivo</em> through suppression of Bcl-2 expression. <strong><em>Conclusion:</em></strong> 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.