Lactobacillus acidophilus and Bifidobacterium longum exhibit antiproliferation, anti-angiogenesis of gastric and bladder cancer: Impact of COX2 inhibition

Abstract

BackgroundProbiotics have gained exponential attention worldwide because they are used as a therapeutic tool for management, prevention and treatment of diseases like cancer. Here, antiproliferation, anti-angiogenesis and antitumor effects of Lactobacillus acidophilus (LA) and Bifidobacterium longum (BL) were examined on gastric (AGS) and bladder (J253) cancer cell lines. MethodsCancer cell viability was monitored with MTT assay. The chick embryo chorioallantoic membrane (CAM) assay was used to screen tumor growth and hemoglobin content of cancer cells alone and with different LA and BL concentrations. Protein expression of COX2 was analyzed with Western blot in cell lines treated with LA, BL, celecoxib at 60 and 100 μM, or their combination. ResultsTreatment with either probiotic showed increased vacuolated gastric cancer (AGS) cells with significant morphological changes at high concentration (2.5 × 107 cfu/ml) of LA and BL bacteria compared to bladder cancer cells (J253). Similarly, AGS cells responded well to LA and BL and there was decreased cancer cell viability, tumor weight and hemoglobin content (p < 0.001). The probiotics were more potent against AGS than J253. High dose (2.5 × 107 cfu/ml) of probiotic bacteria when combined with 60 μM celecoxib downregulated COX2 expression in AGS by 70 % and 95 % (p < 0.001), without affecting COX1 expression. However, J253 cells did not show any changes in the expression of COX2 with probiotics, which is consistent with no effect on cancer cell viability and tumor angiogenesis. ConclusionsThis study is the first to document antiproliferation and anti-angiogenesis of LA and BL against gastric cancer by downregulating COX2 expression. LA and BL might be new, safe agents for targeting COX2 and suppressing growth of some cancers.