Neutrophil extracellular traps promote surgery-induced peritoneal carcinosis of metastatic colorectal cancer via modulation of CXCR2 and αv integrin

• Introduction: Peritoneal carcinosis (PC) is the third common site of metastatic colorectal cancer which characterized by a very low survival rate. Surgical trauma has been identified as an important factor in the progression of PC, postulated to be caused by the inflammatory response to tissue injury. The mechanism behind tumor metastasis remains poorly understood. However, existing evidence indicates that neutrophils, via Neutrophil Extracellular Traps (NETs), are implicated in the development of metastatic disease and recently identified as one of the most significant key players in promoting tumor progression. In this study, we highlight the mechanism by which NETs promote surgery-induced colon cancer cell peritoneal metastasis through regulation of key receptors, CXCR2 and αvβ3 integrin.Methods: We developed a murine model of surgical stress-induced PC by post-surgery inoculation of CT-26 murine colon cancer cell line. Surface expression of CXCR2 and αvβ3 on CT-26 cells were evaluated by flow cytometry live staining. Gene expression of extracellular matrix (ECM) proteins from wound incision wall was quantified using qRT-PCR. Function of CXCR2 and αvβ3 in tumor cell migration, proliferation, and adhesion were assessed by blocking assays using CXCR2 antagonist SB225002 and anti-CD51 in vitro and in vivo. Role of neutrophils in promoting cancer cell migration and adhesion was demonstrated using in vitro co-cultured migration and adhesion assays. NET formation was measured using modified ELISA technique of Histone-DNA complex. Depletion of NETs were achieved by daily intraperitoneal administration of 2mg/kg DNase I to mice for 10 days and tumor growth was evaluated by counting macroscopic nodules number on the peritoneum.Results: Blocking CXCR2 and Targeting αv integrin reduced tumor nodules number in vivo by 70% and 65% respectively and decreased cancer cell migration, proliferation, and adhesion in vitro. Incision wound tissue displayed pronounced reduction in ECM proteins mRNAs in treated mice with both CXCR2 antagonist and αv antibody. Mice treatment with DNase I significantly reduced tumor nodules number more than 90% compared to tumor control. Anti-CD51 decreased NET-induced CT-26 cell adhesion. Neutrophils stimulation with MIP-2 exhibits dose-dependent increase of NETosis. Co-culture of neutrophils and cancer cells provoked NETs formation and increased capacity of colon cancer cell migration while DNase I treatment abolished neutrophils NETs-induced tumor cell migration in vitroConclusion: Our novel findings implicate NETs in the development of PC due to surgical stress, suggesting that blocking NET formation might be an interesting potential therapeutic approach.

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MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Cancer och onkologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Cancer and Oncology (hsv//eng)

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