Abstract LB261: Establishment and characterization of a paclitaxel-resistant human triple-negative breast cancer cell line

Abstract

Abstract Triple-negative breast cancer (TNBC) is a lethal female cancer, of which paclitaxel resistance is a major factor limiting treatment outcomes, and continued unmet needs for more effective therapeutic strategies are arduous. The aim of this study is to establish a paclitaxel-resistant TNBC cell line and to characterize the underlying mechanism for potential strategies to overcome the resistance. The human TNBC cell line MDA-MB-231 was exposed to stepwise escalating paclitaxel concentration from 0.5 to 50 nM and a resistant cell line T50R was selected. The IC50 of paclitaxel was 2 and >100 nM in MDA-MB-231 and T50R cells respectively. However, T50R cells required 50 nM Taxol for proliferation. When cultured in the absence of paclitaxel, T50R cells arrested at mitotic stage with high levels of spindle abnormalities. Since induction of microtubule (MT) stabilization plays critical roles in paclitaxel’s potency, we thus measure cell MT polymerization and kinetochore-MT stability. The results showed that, compared to parental MDA-MB-231 cells, the interphase MTs were less polymerized and the kinetochore-MTs were less stable in T50R cells, indicating that the MT dynamic instability was significantly increased in T50R cells. Thus, the increased dynamic unstable MTs in T50R cells might contribute to drug requirement for cell growth and counteract with paclitaxel effects, and consequently lead to drug-resistant phenotype. Identification and interference of endogenous regulators involved in the increased MT instability in T50R cells might provide leads to overcome paclitaxel resistance. Citation Format: Ling-Huei Yih, Hsiao-Hui Kuo, Chieh-Ting Fang. Establishment and characterization of a paclitaxel-resistant human triple-negative breast cancer cell line [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB261.