Biogenic selenium nanoparticles produced by <i>Lactobacillus casei</i> ATCC 393 inhibit colon cancer cell growth <i>in vitro</i> and <i>in vivo</i>

Abstract

Selenium compounds exhibit excellent anticancer properties but have a narrow therapeutic window. Selenium nanoparticles, however, are less toxic compared to other selenium forms, and their biogenic production leads to improved bioavailability. Herein, we used the probiotic strain <i>Lactobacillus casei</i> ATCC 393, previously shown to inhibit colon cancer cell growth, to synthesize biogenic selenium nanoparticles. We examined the anticancer activity of orally administered <i>L. casei</i>, <i>L. casei</i>-derived selenium nanoparticles and selenium nanoparticle-enriched <i>L. casei</i>, and investigated their antitumor potential in the CT26 syngeneic colorectal cancer model in BALB/c mice. Our results indicate that <i>L. casei</i>-derived selenium nanoparticles and selenium nanoparticle-enriched <i>L. casei</i> exert cancer-specific antiproliferative activity <i>in vitro.</i> Moreover, the nanoparticles were found to induce apoptosis and elevate reactive oxygen species levels in cancer cells. It is noteworthy that, when administered orally, selenium nanoparticle-enriched <i>L. casei</i> attenuated the growth of colon carcinoma in mice more effectively than the isolated nanoparticles or <i>L. casei</i>, suggesting a potential additive effect of the nanoparticles and the probiotic. To the best of our knowledge this is the first comparative study examining the anticancer effects of selenium nanoparticles synthesized by a microorganism, the selenium nanoparticle-enriched microorganism and the sole microorganism.