Search

The antimicrobial peptide cathelicidin inhibits development of colitis-associated colon cancer. However, the role of cathelicidin in colon cancer metastasis remains unknown. We hypothesized that cathelicidin is effective in inhibiting colon cancer metastasis. Human colon cancer HT-29 cells were injected intravenously into nude mice. Control HA-tagged adeno-associated virus (HA-AAV) or cathelicidin-overexpressing AAV (CAMP-HA-AAV) were injected intravenously into nude mice on the same day. Four weeks later, the nude mice were assessed for lung and liver metastases. Human colon cancer SW620 cells were used to study the effect of cathelicidin on cell migration and cytoskeleton. Incubation of SW620 cells with cathelicidin dose-dependently reduced cell migration, disrupted cytoskeletal structure, and reduced βIII-tubulin (TUBB3) mRNA expression. The addition of the P2RX7 antagonist KN62, but not the FPRL1 antagonist WRW4, prevented the LL-37-mediated inhibition of cell migration and TUBB3 mRNA expression. The CAMP-HA-AAV-overexpressing group showed significantly reduced human CK20 protein (by 60%) and TUBB3 mRNA expression (by 40%) in the lungs and liver of the HT-29-loaded nude mice, compared to the HA-AAV control group. Intraperitoneal injection of KN62 reversed the CAMP-HA-AAV-mediated inhibition of human CK20 and TUBB3 expression in the lungs and liver of HT-29-loaded nude mice. In conclusion, cathelicidin inhibits colon cancer metastasis via a P2RX7-dependent pathway. Keywords: colon cancer, metastasis, antimicrobial peptide

The proline-rich Akt substrate of 40 kDa (PRAS40) protein is not only a substrate of the protein kinase Akt but also a component of the mTOR complex 1 (mTORC1), thus it links the Akt and the mTOR pathways. We investigated the potential protective role of PRAS40 in cerebral ischemia and its underlying mechanisms by using rats with lentiviral over-expression of PRAS40 and mice with PRAS40 gene knockout (PRAS40 KO). Our results show that gene transfer of PRAS40 reduced infarction size in rats by promoting phosphorylation of Akt, FKHR (FOXO1), PRAS40, and mTOR. In contrast, PRAS40 KO increased infarction size. Although the PRAS40 KO under normal condition did not alter baseline levels of phosphorylated proteins in the Akt and mTOR pathways, PRAS40 KO that underwent stroke exhibited reduced protein levels of p-S6K and p-S6 in the mTOR pathway but not p-Akt, or p-PTEN in the Akt pathway. Furthermore, co-immunoprecipitation suggests that there were less interactive effects between Akt and mTOR in the PRAS40 KO. In conclusion, PRAS40 appears to reduce brain injury by converting cell signaling from Akt to mTOR.

Background & Aims: Cathelicidin (LL-37 in human and mCRAMP in mice) represents a family of endogenous antimicrobial peptides with anti-inflammatory effects. LL-37 also suppresses collagen synthesis, an important fibrotic response, in dermal fibroblasts. Here, we determined whether exogenous cathelicidin administration modulates intestinal fibrosis in two animal models of intestinal inflammation and in human colonic fibroblasts. Methods: C57BL/6J mice (n = 6 per group) were administered intracolonically with a trinitrobenzene sulphonic acid (TNBS) enema to induce chronic (6â7 weeks) colitis with fibrosis. We administered mCRAMP peptide (5 mg/kg every 3 day, week 5â7) or cathelicidin gene (Camp)-expressing lentivirus (107 infectious units week 4) intracolonically or intravenously, respectively. We then infected 129Sv/J mice with Salmonella typhimurium orally to induce cecal inflammation with fibrosis. Camp-expressing lentivirus (107 infectious units day 11) was administered intravenously. Results: TNBS-induced chronic colitis was associated with increased colonic collagen (col1a2) mRNA expression. Intracolonic cathelicidin (mCRAMP peptide) administration or intravenous delivery of lentivirus-overexpressing cathelicidin gene significantly reduced colonic col1a2 mRNA expression in TNBS-exposed mice compared with vehicle administration. Salmonella infection also caused increased cecal inflammation associated with collagen (col1a2) mRNA expression that was prevented by intravenous delivery of Camp-expressing lentivirus. Exposure of human primary intestinal fibroblasts and human colonic CCD-18Co fibroblasts to transforming growth factor-β1 (TGF-β1) and/or insulin-like growth factor 1 induced collagen protein and mRNA expression, which was reduced by LL-37 (3â5 μM) through a MAP kinase-dependent mechanism. Conclusions: Cathelicidin can reverse intestinal fibrosis by directly inhibiting collagen synthesis in colonic fibroblasts. Keywords: Antimicrobial Peptide, Collagen, Inflammatory Bowel Disease