Selenium-enriched Arthrospira platensis potentiates docetaxel, oxaliplatin, and topotecan anticancer activity in epithelial tumors

Abstract

Docetaxel (DOC), oxaliplatin (OXA), and topotecan (TOPO) are effective chemotherapy agents in human cancers, but their clinical use is limited by severe side effects. Arthrospira platensis, a cyanobacterium that is widely used as a nutritional supplement, can accumulate in a dose- and time-dependent manner high amounts of selenium (Se), a trace element with potential anticancer effects. In this study, we (1) tested the in vitro effects of A. platensis enriched with Se alone or combined with DOC, OXA, or TOPO (IC50 concentrations) on cell proliferation, in situ apoptosis, and reactive oxygen species (ROS) production in human epithelial colorectal adenocarcinoma (Caco-2) and prostate cancer (DU145) cell lines and (2) assessed the in vivo effect on tumor growth in mice xenografted with renal carcinoma cells (RCC 786-0). Neither Se nor Se-enriched A. platensis affected the viability significantly. Incubation of Caco-2 or DU145 cells with Se + DOC, Se + OXA, or Se + TOPO-enriched A. platensis increased significantly the cytotoxicity of each drug by 85–99 % (compared with cells treated with anticancer drug alone) through promotion of caspase-3-mediated apoptosis and reduction of ROS production. In vivo, treatment with Se + TOPO-enriched A. platensis for 4 weeks significantly reduced tumor growth compared with placebo or Se-enriched A. platensis alone (p < 0.05). The Se + antimitotic drug-enriched A. platensis formulation using Se-enriched A. platensis as a vector for anticancer drug delivery could represent a new strategy for the development of effective and less toxic treatments against cancer.