MicroRNAs (miRNAs) have emerged as key players in tumor angiogenesis. Interleukin-17C (IL-17C) was identified to promote colorectal cancer (CRC) progression. Therefore, we aimed to investigate the effect of IL-17C on tumor angiogenesis, the involvement of miR-23a-3p in IL-17C signaling, and the direct target gene of miR-23a-3p in CRC. In vitro and ex vivo angiogenesis, a mouse xenograft experiment, and immunostaining were performed to test the effect of IL-17C on tumor angiogenesis. ELISA, quantitative real time PCR, and gene silencing were used to uncover the underlying mechanism. IL-17C induced angiogenesis of intestinal endothelial cells, subsequently enhancing cell invasion and migration of DLD-1 cells. IL-17C-stimulated DLD-1 cells produced vascular endothelial growth factor (VEGF) to enhance angiogenesis. Moreover, IL-17C markedly accelerated xenograft tumor growth, which was manifested by substantially reduced tumor growth when treated with the VEGF receptor 2 inhibitor Ki8751. Accordingly, Ki8751 suppressed the expression of IL-17C-stimulated PECAM and VE-cadherin in xenografts. Furthermore, IL-17C activated STAT3 to increase the expression of miR-23a-3p that suppressed semaphorin 6D (SEMA6D) expression, thereby permitting VEGF production. Taken together, our study demonstrates that IL-17C promotes tumor angiogenesis through VEGF production via a STAT3/miR-23a-3p/SEMA6D axis, suggesting its potential as a novel target for anti-CRC therapy.

To develop a 5-aminosalicylic acid (5-ASA)-based anticolitic drug with enhanced therapeutic activity, a colon-targeted codrug constituting 5-ASA and a GPR109A agonist was designed. 5-ASA azo-coupled with nicotinic acid (ASA-azo-NA) was synthesized, and the colon specificity and anticolitic effects were evaluated. Approximately 89% of ASA-azo-NA was converted to 5-aminonicotinic acid (5-ANA) and 5-ASA after 24 h of incubation in the cecal contents. 5-ANA was identified as a GPR109A agonist (concentration that gives half-maximal response (EC 50 ): 18 μM) in a cellbased assay. Upon oral gavage of ASA-azo-NA (oral ASA-azo-NA) and sulfasalazine (oral SSZ), a colon-targeted 5-ASA prodrug, cecal accumulation of 5-ASA was comparable, and 5-ANA was barely detectable in the blood, while it was detected up to 62.7 μM with oral 5-ANA. In parallel, oral ASAazo-NA did not elicit an adverse skin response. In murine macrophage and human colon carcinoma cells, activation of GPR109A by 5-ANA elevated the level of the anti-inflammatory cytokine IL-10, suppressed NF-κB activation, and potentiated the inhibitory activity of 5-ASA on NF-κB. Oral ASA-azo-NA ameliorated rat colitis and was more effective than oral SSZ, which were substantially blunted following cotreatment with the GPR109A antagonist, mepenzolate. In conclusion, ASA-azo-NA is a colon-targeted anticolitic codrug with a reduced risk of skin toxicity induced by the GPR109A agonist, therapeutically surpassing a current 5-ASA-based anti-inflammatory bowel disease drug in a rat colitis model.

Intestinal wound healing is a new therapeutic goal for inflammatory bowel disease (IBD) as complete healing of the mucosa is the key element of clinical remission in IBD. Previous studies showed that termination of inflammation can be achieved by adding pro-resolving lipids like DHA and EPA exogenously. However, the roles of these lipids in mucosal healing have not been investigated. To recapitulate intestinal healing process, mice were received dextran sodium sulfate (DSS) for 7 days in the drinking water followed by regular tap water for 5 additional days. DSS-induced intestinal inflammation featuring body weight loss, histological tissue damage, increased cytokine production and infiltration of inflammatory cells was gradually reduced upon switching to water. To investigate whether endogenous lipids play a role in mucosal healing, the lipidomics analysis of mouse serum was performed. Reduced levels of arachidonic acid, the biosynthetic precursor of prostaglandin F (PGF)2α, 19H-PGF1α, the metabolite of prostacyclin, and 20H-PGF2α, the metabolite of PGF2α, suggest subsiding inflammation. In contrast, increased levels of an active metabolite of resolvin D1 along with decreased levels of its precursor DHA as well as decreased levels of the precursor of resolvin E, 18-hydroxy-eicosapentaenoic acid, suggest inauguration of mucosal healing by endogenous lipids. Furthermore, exogenously supplied fish oil enhanced the process even further. These results suggest the presence of mucosal healing regulated by endogenous pro-healing lipids and also indicate that the remission state of IBD could be prolonged by enhancing the levels of these lipids.

Protease-activated receptor 2 (PAR2) regulates inflammatory responses and lipid metabolism. However, its precise role in colitis remains unclear. Here, we aimed to investigate the function of PAR2 in high-fat diet fed mice with colitis and its potential role in autophagy. PAR2+/+ and PAR2-/- mice were fed a high-fat diet (HFD) for 7 days before colitis induction with dextran sodium sulfate. Deletion of PAR2 and a HFD significantly exacerbated colitis as shown by increased mortality, body weight loss, diarrhea or bloody stools, colon length shortening, and mucosal damage. Pro-inflammatory cytokine levels were elevated in HFD-fed PAR2-/- mice and in cells treated with the PAR2 antagonist GB83, palmitic acid (PA), and a cytokine cocktail (CC). Damaging effects of PAR2 blockage were associated with autophagy regulation by reducing the levels of YAP1, SIRT1, PGC-1α, Atg5, and LC3A/B-I/II. Additionally, mitochondrial dysfunction was demonstrated only in cells treated with GB83, PA, and CC. Reduced cell viability and greater induction of apoptosis, as shown by increased levels of cleaved caspase-9, cleaved caspase-3, and cleaved PARP, were observed in cells treated with GB83, PA, and CC but not in those treated with only PA and CC. Collectively, protective effects of PAR2 were elucidated during inflammation accompanied by high-fat environment by promoting autophagy and inhibiting apoptosis, suggesting PAR2 as a therapeutic target for inflammatory bowel disease co-occurring with metabolic syndrome.

Inflammatory mediators modulate inflammatory pathways during the development of colorectal cancer. Inflammatory mediators secreted by both immune and tumor cells can influence carcinogenesis, progression, and tumor metastasis. The gut microbiota, which colonize the entire intestinal tract, especially the colon, are closely linked to colorectal cancer through an association with inflammatory mediators such as tumor necrosis factor, nuclear factor kappa B, interleukins, and interferons. This association may be a potential therapeutic target, since therapeutic interventions targeting the gut microbiota have been actively investigated in both the laboratory and in clinics and include fecal microbiota transplantation and probiotics.