Abstract 3645: OSM-induced LOXL2 expression hinges on upregulation of c-Myc and promotes tumor growth and metastasis, IL-1beta plays synergistic role in LOXL2 expression
Authors: Dinca Simion , Wolf Cody , Bond Laura , Jorcyk Cheryl 
Published: April 2023

Ductal carcinoma is the most commonly diagnosed breast cancer in women, the presence of metastases drops patient five-year survival from 95% to an abysmal 27%. This makes studying the mechanisms that promote metastasis of critical importance. Research shows that the extracellular matrix (ECM) of the tumor microenvironment (TME) plays an important role in invasive ductal carcinoma (IDC) progression and metastasis. Specifically; the density, stiffness, and orientation of collagen I fibers in the stroma all impact IDC motility, invasion, and metastasis. Lysyl oxidase-like 2 (LOXL2) is a secreted enzymatic protein that is implicit in ECM remodeling. By catalyzing an oxidative reaction in peptidyl lysine/hydroxylysine present on collagen I fibers, LOXL2 initiates crosslinking of the fibers. Our previous publication demonstrates that interleukin-6-related pro-inflammatory cytokine signaling, specifically oncostatin M (OSM), led to the overexpression and secretion of the LOXL2 enzyme. This increased the metastatic potential of IDC cells by promoting the crosslinking and alignment of collagen I fibers, which in turn led to increased invasion in 3D collagen I matrices. Thus, we hypothesize that OSM-induced LOXL2 expression, secretion, and subsequent collagen I fiber crosslinking and alignment, leads to an increase in IDC metastasis. In vivo studies utilizing nude athymic mice injected with either MCF7-Luc-EV control or MCF7-Luc-OSM overexpressing cells were performed in conjunction with LOXL2 inhibition using specially designed chow containing either LOXL2 SMI or control. Further analysis of OSM signaling pathways was performed in MCF7 and MDA-MB-468 IDC cells to determine mechanism for OSM induction of LOXL2. Our studies demonstrate that canonical OSM signaling pathways (pERK, pSTAT3, and pAKT) all contribute to LOXL2 expression in MCF7 cells suggesting a possible mediator protein we identified as c-Myc. Furthermore, OSM-induced LOXL2 played a significant role in OSM promoted tumor growth and metastasis as LOXL2 inhibition led to decreased tumor size and far less metastatic lesions. We also analyzed and confirmed a synergistic interaction between OSM and interleukin-1beta (IL-1β) in LOXL2 expression. These results confirm the significance of LOXL2 expression in OSM promoted metastasis and suggests LOXL2 would be an important target for future breast cancer therapies, specifically in patients with elevated levels of OSM. Furthermore, the synergistic interaction between OSM and IL-1β in LOXL2 expression suggests that patients with high levels of both cytokines are at even greater risk of metastasis, making these great markers for determining at risk IDC patients.

Citation Format: Simion Dinca, Cody Wolf, Laura Bond, Cheryl Jorcyk. OSM-induced LOXL2 expression hinges on upregulation of c-Myc and promotes tumor growth and metastasis, IL-1beta plays synergistic role in LOXL2 expression. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3645.