Neutrophil (PMN) infiltration and accumulation in mucosal tissues often leads to exacerbated inflammation and injury; both are major risk factors for cancer. Indeed, patients with Inflammatory Bowel Diseases, featuring en-masse PMN infiltration of the intestinal mucosa, are at a significantly higher risk of developing colorectal cancer (CRC). PMN pathology is often associated with genotoxic stress, which can lead to genomic instability and carcinogenesis, as well as with secretion of soluble proteinases that can dramatically alter tissue/tumor microenvironment and affect cell polarity, migration and proliferation. Our preliminary findings show that migrating PMNs release small membrane particles (microparticles, PMN-MPs) rich in micro-RNAs (miRNAs) and active metaloproteinases (MMPs). PMN-MPs were found to provide protection and efficient shuttle miRNAs and MMPs to surrounding epithelial/cancer cells to locally mediate potent effects on cellular function. Specifically, PMN-MP binding to cancer cells resulted in inhibition of the repair of double stranded DNA breaks (DSBs) by homologues recombination (HR), thus facilitating accumulation of DNA damage. Furthermore, PMN-MPs were found to potently cleave epithelial cadherins (which act as tumor suppressors), induce expression of vimentin (a key regulator of cell motility and EMT) and inactivation of tumor suppressor gene TP53, thus likely facilitating cellular transformation and EMT. We further found that ICAM-1 signaling (a PMN ligand expressed by metastatic tumor cells) triggered by direct PMN binding interactions with tumor cells increased tumor cell survival and proliferation, to likely promote colonization of distant organs. Thus, PMNs can play key roles in carcinogenesis and metastasis, but exactly how this happens is unclear. This proposal will examine PMN function at the primary tumor site (colon), the circulation, and sites of metastasis (liver) to test the overarching hypothesis that PMNs play a critical role in inflammation-driven CRC development and metastatic tissue colonization. The hypothesis will be tested through the three specific aims: Aim 1 will use an established and our own unique CRC mouse models in combination with PMN recruitment deficient mouse models to determine the role for PMN-derived micro-RNAs in promoting genomic instability and cellular transformation. Aim 2 will use innovative biochemical and molecular approaches to determine the role of PMNs/PMN-derived MPs in transcription of key EMT regulators and expression/localization of downstream junctional and cytoskeletal effector proteins, to promote EMT and tumor dissemination. Finally, Aim 3 will employ cutting edge intravital imaging of liver vasculature and tumor tissue in fluorescence reporter mice, complemented with flow cytometric analysis to determine whether ICAM-1-dependent, PMN-CRC cell binding interactions and the resulting signaling events promote CRC cell survival and growth, thus facilitating expansion of metastatic lesions. The outlined experiments will address the specific contribution of PMNs during several stages of tumor progression, thus will have a high likelihood of identifying multiple new targets for future therapeutic approaches aimed at preventing cancer growth and metastasis.
|Effective start/end date||1/1/18 → 12/31/21|
- American Cancer Society (RSG-17-235-01-CSM)