Therapeutic Role of Secondary Metabolites from Probiotic Strains for Ehrlich Solid Tumors in Mice

Abstract

This study aimed to screen the bioactive components in Streptococcus equinus WC1 (SE-WC1) and Limosilactobacillus reuteri GM4 (LR-GM4) and estimate the therapeutic role in Ehrlich solid tumors (EST) mice model. Forty-four male albino EST mice were assigned into 7 groups and treated daily for 2 weeks, including the EST group, the EST mice that received SE-WC1 at a low or a high dose (0.5 ml *106 or 0.5 ml *108 cfu), the EST mice that received LR-GM4 at the low or the high dose (0.5 ml *106 or 0.5 ml *108 cfu), and the EST mice that received SE-WC1 plus LR-GM4 at the low or the high dose. Tumors were harvested, weighed, examined, and used for the determination of apoptosis-related gene expression. Samples of the intestine, liver, and kidney were gathered for histological examination. The GC-MS identified 24 and 36 bioactive compounds in SE-WC1 and LR-GM4, respectively. The main compound in SE-WC1 was lupeol; however, the main compound in LR-GM4 was retinaldehyde. EST mice showed disturbances in Bcl-2, Bax, and p53 mRNA expression along with histological changes in the intestine, liver, and kidney. Administration of both bacterial strains reduced the tumor weight, alleviated the disturbances in the gene expression, and improved the histological structure of the intestine, liver, and kidney in a dose-dependent. Moreover, LR-GM4 was more effective than SE-WC1 due to its higher content of bioactive compounds. It could be concluded that these strains of probiotics are promising for the treatment of solid tumors.