Role of peptidylarginine deiminase 2 (PAD2) in mammary carcinoma cell migration

• Published in: BMC cancer Vol. 17; no. 1; p. 378
• Main Authors: Horibata, Sachi, Rogers, Katherine E, Sadegh, David, Anguish, Lynne J, McElwee, John L, Shah, Pragya, Thompson, Paul R, Coonrod, Scott A
• Format: Journal Article
• Language: English
• Published: England BioMed Central 26-05-2017; BMC
• Subjects: Animals; Breast cancer; Breasts; Carcinoma; Carcinoma, Intraductal, Noninfiltrating - metabolism; Carcinoma, Intraductal, Noninfiltrating - pathology; Cdc42 protein; Cell adhesion; Cell adhesion & migration; Cell Line, Tumor; Cell migration; Cell Movement - physiology; Citrulline; Cytology; Cytoskeleton; Ductal invasion; E-cadherin; Elongation; Female; Humans; Kinases; Mammary gland; Mammary hyperbranching; Mammary Neoplasms, Experimental - metabolism; Mammary Neoplasms, Experimental - pathology; Mesenchyme; Mice; Mice, Transgenic; Organoids; Peptidylarginine deiminase 2 (PAD2); Protein-arginine deiminase; Protein-Arginine Deiminases - metabolism; Rac1 protein; Regulatory proteins; RhoA protein; Rodents; Signal transduction; Transgenic mice; Tumor cell migration; Tumor cells; Tumors; Xenografts; Mammary hyperbranching; Ductal invasion; Peptidylarginine deiminase 2 (PAD2); Tumor cell migration
• ISSN: 1471-2407; 1471-2407
• DOI: 10.1186/s12885-017-3354-x

Penetration of the mammary gland basement membrane by cancer cells is a crucial first step in tumor invasion. Using a mouse model of ductal carcinoma in situ, we previously found that inhibition of peptidylarginine deiminase 2 (PAD2, aka PADI2) activity appears to maintain basement membrane integrity in xenograft tumors. The goal of this investigation was to gain insight into the mechanisms by which PAD2 mediates this process.
For our study, we modulated PAD2 activity in mammary ductal carcinoma cells by lentiviral shRNA-mediated depletion, lentiviral-mediated PAD2 overexpression, or PAD inhibition and explored the effects of these treatments on changes in cell migration and cell morphology. We also used these PAD2-modulated cells to test whether PAD2 may be required for EGF-induced cell migration. To determine how PAD2 might promote tumor cell migration in vivo, we tested the effects of PAD2 inhibition on the expression of several cell migration mediators in MCF10DCIS.com xenograft tumors. In addition, we tested the effect of PAD2 inhibition on EGF-induced ductal invasion and elongation in primary mouse mammary organoids. Lastly, using a transgenic mouse model, we investigated the effects of PAD2 overexpression on mammary gland development.
Our results indicate that PAD2 depletion or inhibition suppresses cell migration and alters the morphology of MCF10DCIS.com cells. In addition, we found that PAD2 depletion suppresses the expression of the cytoskeletal regulatory proteins RhoA, Rac1, and Cdc42 and also promotes a mesenchymal to epithelial-like transition in tumor cells with an associated increase in the cell adhesion marker, E-cadherin. Our mammary gland organoid study found that inhibition of PAD2 activity suppresses EGF-induced ductal invasion. In vivo, we found that PAD2 overexpression causes hyperbranching in the developing mammary gland.
Together, these results suggest that PAD2 plays a critical role in breast cancer cell migration. Our findings that EGF treatment increases protein citrullination and that PAD2 inhibition blocks EGF-induced cell migration suggest that PAD2 likely functions within the EGF signaling pathway to mediate cell migration.