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Background: Several microorganisms inhabit the mammalian gastrointestinal tract and are associated with the pathogenesis of various diseases, including cancer. Recent studies have indicated that several probiotics produce antitumor molecules and inhibit host tumor progression. We demonstrated that heptelidic acid (HA), a sesquiterpene lactone derived from the probiotic Aspergillus oryzae, exerts antitumor effects against pancreatic cancer in vitro and in vivo. In this study, the antitumor effects of HA against extraintestinal melanoma were assessed in vitro and in vivo., Results: Sulforhodamine B (SRB) assay revealed that the growth of B16F10 cells was significantly inhibited by HA in a concentration-dependent manner. The enzymatic activity of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) decreased in proportion with the growth inhibition effect of HA. Moreover, oral HA administration significantly suppressed the growth of transplanted B16F10 tumors without any significant changes in biochemical test values. Moreover, GAPDH activity in the transplanted tumor tissues in the HA group significantly decreased compared with that in the PBS group., Conclusion: This study suggests that orally administered HA was absorbed in the gastrointestinal tract, reached the cancer cells transplanted in the skin, and inhibited GAPDH activity, thereby inhibiting the growth of extraintestinal melanoma cells. Thus, this study proposes a novel system for extraintestinal tumor regulation via gut bacteria-derived bioactive mediators., (© 2022. The Author(s).)

Intake of probiotics or fermented food produced by some probiotic bacteria is believed to exert anti-tumor functions in various cancers, including pancreatic cancer, because several studies have demonstrated the anti-tumor effects of probiotic bacteria in vitro and in vivo in animal carcinogenesis models. However, the mechanisms underlying the anticancer effects of probiotics on pancreatic cancer have not been clarified. In this study, we assessed the anti-tumor effects of probiotic bacteria against pancreatic cancer cells. Among the known probiotic bacteria, Aspergillus oryzae exhibited a strong pancreatic tumor suppression effect. The culture supernatant of A. oryzae was separated by HPLC. Heptelidic acid was identified as an anti-tumor molecule derived from A. oryzae by LC-MS and NMR analysis. The anti-tumor effect of heptelidic acid was exhibited in vitro and in vivo in a xenograft model of pancreatic cancer cells. The anti-tumor effect of heptelidic acid was exerted by the p38 MAPK signaling pathway. Heptelidic acid traverses the intestinal mucosa and exerts anti-tumor effects on pancreatic cancer cells. This is a novel anti-tumor mechanism induced by beneficial bacteria against pancreatic cancer in which bacterial molecules pass through the intestinal tract, reach the extra-intestinal organs, and then induce apoptosis via an inducible signaling pathway.

Inflammatory bowel disease (IBD), such as ulcerative colitis (UC) and Crohn's disease (CD), is an intractable intestinal inflammation associated with the disruption of the intestinal mucosa. We previously demonstrated that Lactobacillus brevis -derived long-chain polyphosphate (poly P) improved the intestinal barrier function by the upregulation of cell adhesion and relieved intestinal inflammation, thereby exerting a curing effect on colitis in vitro , in vivo , and in an investigator-initiated clinical study of UC. However, how poly P improves mucosal defects induced by intestinal inflammation has not been elucidated. In this study, we detected the accumulation of platelets in inflamed tissues induced by poly P in a dextran sulfate sodium- (DSS-) induced colitis mouse model. A light transmission aggregometry analysis and scanning electron microscopy showed that poly P promoted the platelet aggregation. An SRB assay and ki-67 staining showed that the supernatant of poly P-treated platelet-rich plasma (PRP) increased intestinal epithelial cell growth. A wound healing assay showed that the supernatant of poly P-treated PRP, but not poly P itself, accelerated wound healing. A Western blotting analysis indicated that mitogen-activated protein kinase activation was induced by the supernatant of poly P-treated human PRP in the epithelial cells and its wound healing effect was significantly decreased by the inhibition of ERK signaling. These data suggested that platelet-derived mediators induced by poly P improved intestinal inflammation through the promotion of epithelial cell growth by the activation of the ERK signaling pathway. The mechanism is a novel host-microbe interaction through mammalian platelet-derived mediators induced by bacterial molecules., Competing Interests: Dr. Fujiya obtained sodium polyphosphate used for the production of calcium polyphosphate in this study from Kamui Pharma Inc., (Copyright © 2021 Shotaro Isozaki et al.)