Abstract C141: Inactivating the mitotic kinases TTK and NEK2 as a promising approach for the reduction of metastasis in triple-negative breast cancer in non-Hispanic Blacks and Hispanic/Latinas

Abstract Triple-negative breast cancer (TNBC) is the most aggressive type of breast cancer in women worldwide. It is associated with uncontrolled cell proliferation, increased rates of centrosome amplification, genetic instability, and invasive capacity. Advanced stages of TNBC with distant metastasis are virtually incurable, with chemotherapy as the primary treatment option. Non- Hispanic Black (NHB) and Hispanic/Latino (H/L) women have lower 5-year survival rates when compared to non-Hispanic White (NHW) women with breast cancer, in part because their breast tumors are detected at higher stages, and due to elevated rates of TNBC. Women with a higher percentage of African ancestry have been shown to have a higher expression of multiple mitotic kinases. Mitotic kinases, such as TTK, maintain genomic integrity, while NEK2 modulates centrosome separation and microtubule organization. However, their overexpression in breast cancer is associated with cell proliferation, chromosome instability, aneuploidy, and early stages of metastasis (the epithelial-to-mesenchymal transition, or EMT, cell migration and invasion). A tissue microarray confirmed associations between TTK overexpression, proliferation, and EMT markers in breast tumors and the TNBC subtype. Thus, we aim to measure protein and mRNA expression levels of EMT markers upon downregulation of TTK and NEK2. To address this, mesenchymal TNBC cell lines, MDA-MB-231 (NHW) or MDA-MB-157 (NHB), were cultured in DMEM and 10% FBS, followed by TTK siRNA, NEK2 siRNA, or double transfection. TRIzol was then used for protein and RNA extraction. Western blot and qPCR analyses measured EMT markers' protein and mRNA expression levels, respectively. Preliminary results from these experiments showed that silencing of TTK, NEK2, or TTK/NEK2 resulted in a reduction of the mRNA expression levels of Vimentin, N-cadherin, and β-Catenin in MDA-MB- 231 cell lines. Moreover, data showed a decrease in Vimentin in all treatment groups at the protein level. TTK/NEK2 knockdown also reduced N-cadherin and β-Catenin protein expression levels. These preliminary data suggest that silencing of mitotic kinases TTK and NEK2 may be a promising approach for targeting early stages of metastasis in TNBCs. Because of their increased expression in women of African heritage, anti-mitotic kinase inactivation can be a novel approach that can highly benefit women of the West African diaspora with breast cancer, including African American and Caribbean Hispanics, specifically by diminishing cancer cell survival and metastasis. Citation Format: Alexandra N Aquino-Acevedo, Ángel D. Colón-Burgos, Gretchen M. Albarrán-Acosta, Marileana Rodríguez-Ruiz, Joel A. Orengo-Orengo, Melanie E. Cruz- Robles, Harold I. Saavedra. Inactivating the mitotic kinases TTK and NEK2 as a promising approach for the reduction of metastasis in triple-negative breast cancer in non-Hispanic Blacks and Hispanic/Latinas abstract. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr C141.