Selenium nanoparticles enhance anticancer effects by modulating LAMP1, autophagic machinery and P53 expressions in colon cancer cells

Colorectal cancer (CRC) is one of the most prevalent malignancies worldwide, with its incidence continuing to rise due to changes in lifestyle and dietary habits. Selenium, an essential trace element, possesses antioxidant, anti-inflammatory, and anticancer properties, making it a promising therapeutic candidate for CRC. This study aimed to synthesize nanomodified Selenium (Nano-Selenium), compare its anticancer efficacy with conventional Selenium and Sorafenib, evaluate its cytotoxicity toward normal colon epithelial cells, and investigate its underlying molecular mechanisms in colon cancer cells. Nano-Selenium was synthesized by dissolving Selenium in an oil phase containing Span 80 as a stabilizing emulsifier, followed by high-pressure homogenization to generate nanoparticles with diameters below 100 nm. Automated microscopic analysis demonstrated particle sizes ranging from 10 to 50 nm for Nano-Selenium, whereas conventional Selenium particles measured approximately 1–3 μm. Zeta potential analysis confirmed the superior physicochemical stability of Nano-Selenium over a 24-hour period. The antiproliferative activity of Selenium, Nano-Selenium, and Sorafenib was evaluated using MTT assays in Caco-2, HT-29, and HCT-116 colon cancer cell lines and the normal colon epithelial cell line NCM-460. Nano-Selenium exhibited significantly greater antiproliferative activity against all colon cancer cell lines while displaying lower cytotoxicity toward normal cells than conventional Selenium and Sorafenib. The IC₅₀ values of Nano-Selenium were below 5 µM in all cancer cell lines, compared with approximately 10 µM for conventional Selenium. In contrast, the IC₅₀ values in NCM-460 cells were approximately 27 µM for Nano-Selenium, 16 µM for conventional Selenium, and 14.5 µM for Sorafenib. Sorafenib exhibited IC₅₀ values of 12.2, 9.25, and 7.5 µM in Caco-2, HT-29, and HCT-116 cells, respectively. Unlike Selenium and Sorafenib, treatment of Caco-2 cells with 5 µM Nano-Selenium markedly reduced cell viability while inducing only minimal membrane damage, as evidenced by limited lactate dehydrogenase (LDH) release. Nano-Selenium significantly enhanced apoptosis by increasing early and late apoptotic populations, activating Caspase-3, upregulating the tumor suppressor p53, and downregulating lysosomal-associated membrane protein-1 (LAMP1). Furthermore, Nano-Selenium increased the expression of the autophagy-related proteins ATG5 and LC3B and disrupted autophagic flux, suggesting inhibition of lysosome–autophagosome fusion. ELISA analysis further demonstrated a time-dependent reduction in TNF-α levels accompanied by a marked increase in IL-6 levels. In conclusion, Nano-Selenium demonstrated superior anticancer efficacy and selectivity compared with conventional Selenium and Sorafenib by suppressing lysosomal function, disrupting autophagic flux, and activating p53-mediated apoptotic pathways while exerting minimal toxicity toward normal colon epithelial cells. These findings highlight Nano-Selenium as a promising therapeutic strategy for CRC. Keywords : Colon cancer, Nanomodified Selenium, LAMP1, P53, autophagy.