Salmonella alters heparanase expression and reduces tumor metastasis

Salmonella causes salmonellosis, is a facultative anaerobe and is one of the common Gram-negative bacteria. Salmonella has anti-tumor potential and tumor-targeting activity. The heparin sulfate on cell surfaces can be cleaved by heparanase that is an endo-β-D-glucuronidase. Heparanase can destroy the extracellular matrix and is involved in tumor metastasis and angiogenic activity. Previously, Salmonella was demonstrated to inhibit tumor metastasis. It remains unclear whether Salmonella inhibits metastasis by regulating heparanase. The expression of heparanase in Salmonella-treated tumor cells was found to be decreased. Transwell and wound-healing assays demonstrated the inhibition of cell migration after Salmonella treatment. Salmonella was found to influence the levels of phosphate-protein kinase B (P-AKT) and phosphate-extracellular regulated protein kinases (P-ERK), which are involved in heparanase expression. Salmonella reduced the heparanase expression induced upregulating PERK and PAKT signaling pathways. The mice bearing an experimental metastasis tumor model was used to evaluate the anti-tumor metastatic effects of Salmonella. Compared with the control group, Salmonella significantly reduced the number of metastatic nodules and enhanced survival. The results of our study indicate that Salmonella plays a vital role in the inhibition of tumor metastasis through the downregulation of heparanase.