Abstract 2545: Nek2 and other mitotic kinases are downstream of the E2F activators, and may modulate the epithelial-to-mesenchymal transition in breast cancer

Abstract

Abstract The E2F transcription factors have been extensively studied in cancer since they are known for their role in the regulation of cell cycle progression, centrosome duplication, cell survival, and other functions. We recently demonstrated that the E2F activators (E2F1, E2F2, and E2F3) regulate mitosis through the elevated expression of multiple mitotic proteins including Sgo1, Nek2, Hec1, BubR1, and Mps1. We have shown that Mps1 triggers EMT through multiple mechanisms. NIMA-related kinase 2 (Nek2) is a centrosome-associated protein kinase particularly abundant in cells during the G2-M phase, which primary function is to phosphorylate centrosome linker proteins to cause centrosome disjunction and the formation of the bipolar mitotic spindle. Previous results from our lab showed that overexpression of Nek2 in HCC1954 (Her2+ breast cancer cell line) with a knock down for E2F3 rescued a high centrosome amplification pattern and enhances the formation of invasive protrusions. cBioportal analysis using the TCGA database showed Nek2 mRNA alterations in 9.1% of breast cancer patients and is predominantly present in tumors that are ER-, PR-, and Her2- (25%). Similarly, analysis using the METABRIC database showed Nek2 mRNA alterations in 6.1% of breast cancer patients and is predominantly present in tumors from basal (24%), Her2+ (10%), and luminal B (13.9%) subtypes. Based on these results, we hypothesize that Nek2 overexpression has a role in the epithelial-to-mesenchymal (EMT) pathway leading to cell migration and invasion as prelude to metastasis in breast cancer. To address this, we used MCF10A non-tumorigenic mammary cells with or without the overexpression of Nek2 (MCF10A/GFP and MCF10A/GFP-Nek2). Our preliminary data indicates that overexpression of GFP-Nek2 in mammary epithelial cells enhances levels of vimentin, whereas decreased the levels of E-cadherin, suggesting a role of Nek2 in a mesenchymal state. Likewise, siRNA-mediated silencing of Nek2 in mesenchymal breast cancer cells modulates markers of EMT. Because inhibitors are available for Nek2, it would be feasible to target this kinase to combat metastatic HR- breast cancers. Our work will allow the identification of mechanistic molecular pathways influenced by Nek2 role in driving invasion and metastasis to highlight this mitotic kinase as a potential prognostic marker for high-risk breast tumors. Citation Format: Yainyrette Rivera-Rivera, Mihaela Marina, Harold I. Saavedra. Nek2 and other mitotic kinases are downstream of the E2F activators, and may modulate the epithelial-to-mesenchymal transition in breast cancer [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 2545.