Abstract 2851: The effects of nidogen-1 on proliferation and migration in claudin-low mammary tumor cells

Abstract Breast cancer is the most common type of cancer among women, with one subset of the triple-negative subtype, claudin-low, known to be very aggressive and metastatic. For invasion and metastasis to occur, cancer cells must cross basement membranes, which contain structural proteins such as laminin and collagen IV and linking proteins such as perlecan and nidogen, to colonize distant tissues. Nidogen is a glycoprotein that makes up 2-3% of basement membranes and has two types: nidogen-1 (NID1) and nidogen-2 (NID2). There have been limited studies on NID1 in cancer, with results demonstrating decreased invasiveness and metastatic capabilities in Nid1 silenced cells of various cancer types. In previous work, a murine cell line representative of the claudin-low subtype, known as RJ423, was developed; it demonstrated a 5000-fold increase in Nid1 expression compared to the luminal subtypes. To test whether high Nid1 expression contributes to the aggressive, metastatic nature of claudin-low tumors, Nid1 levels were knocked down in RJ423 cells and proliferation and migratory capabilities were assessed. Phospho-histone H3 immunofluorescence demonstrated that suppressing NID1 reduced RJ423 cell proliferation significantly. Also, proliferation was explored using flow cytometry to obtain cell cycle profiles, and it was observed that there was a reduction in the G2 phase of NID1-suppressed cells. Additionally, apoptosis was assessed through flow cytometry to determine annexin V levels, but suppression of NID1 levels did not alter apoptosis. Furthermore, invasion assays demonstrated a reduction in migration through collagen IV-coated wells using NID1-suppressed cells. Knockdown of Nid1 expression in RJ423 cells reduced the level of NID1 in conditioned media, and preliminary studies suggest that the levels of NID1 in conditioned media can influence tumor cell growth. These findings suggest that NID1 could be targeted to lessen the metastatic nature of claudin-low breast cancer. Citation Format: Rebecca Jagroop, Roger Moorehead. The effects of nidogen-1 on proliferation and migration in claudin-low mammary tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2851.