Anticancer effect of a combinatorial treatment of 5-fluorouracil and cell extract of some probiotic lactobacilli strains isolated from camel milk on colorectal cancer cells

Colorectal cancer (CRC) has the highest mortality rate among cancer types, emphasizing the need for auxiliaries to 5-fluorouracil (5-FU) due to resistance and side effects. Metabolites produced by probiotic bacteria exhibit promising anticancer properties against CRC. In the current study, the anticancer effects of cell extract of three potential probiotic lactobacilli strains isolated from camel milk, Lactobacillus helveticus, Lactobacillus gallinarum, and Lactiplantibacillus plantarum, as well as that of the standard probiotic strain Lacticaseibacillus rhamnosus GG (LGG), on the human colon cancer cell line (HT-29) and the normal HEK293 cell line separately or in combination with 5-FU, were evaluated. This study isolated strains from camel milk and compared their probiotic properties to those of LGG. The cell viability, cell apoptosis, and Th17 cytokine production were assessed using the MTT assay, acridine orange/ethidium bromide (AO/EB) staining, and flow cytometry techniques, respectively. The cell extracts of lactobacilli strains combined with 5-FU reduced HT-29 cell viability effectively and increased cell apoptosis. Nevertheless, the cell extracts of lactobacilli strains combined with 5-FU controlled the cytotoxic impact of 5-FU on HEK-293 cell viability and reduced cell apoptosis. No significant differences were observed among the strains. Moreover, the cell extracts from the strains combined with 5-FU increased the levels of cytokines IFN-γ, TNF-α, and IL-17A, all of which contribute to immunity against tumors. The performance of the studied strains was similar to that of the standard probiotic strain (LGG). The investigation revealed that cell extracts from lactobacilli strains may serve as a promising complementary anticancer treatment.