Synergistic Inhibition of Lactobacillus Rhamnosus and Cisplatin on the Multiplication of Tumoral Cells in BALB/c Mice with Breast Cancer

The probiotic strains of Lactic Acid Bacillus (LAB) not only affect gastrointestinal tract microflora and stimulate local immune system of this tract but also modify and stimulate systemic immunity by influence on lymph nodes and spleen. Several studies have shown the anti-tumor effect of these kinds of bacteria. This study was designed to assess the probiotic effects of lactobacillus rhamnosus on cisplatin efficacy among Balb/c mice with breast cancer. L. rhamnosus strain was inoculated in MRS agar and cultivated for 24 h at 37 °C. Female BalbC mice (n=20) with invasive ductal carcinoma transplantation were divided into four groups: Control, L. rhamnosus, cisplatin and cisplatin plus L. rhamnosus. Cisplatin (5 mg/kg, i.p.) was injected twice a week. Lr was administered daily by gastric intubation (3×10 8 CFU/day). The tumor size was measured every 3 days and mice were sacrificed 24 h after the last injection and tumor tissue was removed for more tests. The results showed that oral administration of L. rhamnosus decreased the growth rate of tumor (p<0.05). One reason for antineoplastic effect of lactobacilli is immune system enhancement. The results of delayed-type hypersensitivity show the stimulation of immune system and inhibition of tumor growth by this mechanism. In pathologic assessments probiotic administration increased the antineoplastic effect of cisplatin. According to the findings of this study it can be expected that human studies also show the satisfactory effect of lactobacillus administration besides common therapeutic methods for cancer treatment.