Downregulation of AURKA and AURKB promotes a decrease in cell invasion in TNBC by modulating the expression of SNAIL1

Although chemotherapy is still the gold standard treatment in TNBC, patients often experience high levels of recurrence. Additionally, several studies have demonstrated that non-Hispanic Black (NHB) and Hispanic/Latino (H/L) women are more likely to be diagnosed and die from TNBC compared to non-Hispanic White women (NHW), indicating a significant health disparity in TNBC. While different molecular players can drive this aggressiveness and resistance in TNBC, mitotic kinases such as AURKA and AURKB are overexpressed in NHB diagnosed with TNBC. AURKA and AURKB play a pivotal role in regulating the cell cycle by promoting centrosome maturation, mitotic spindle formation, and proper chromosome alignment and segregation. However, when dysregulated, they can contribute to the epithelial-to-mesenchymal transition (EMT) by promoting the expression of EMT drivers. We hypothesize that the combined knockdown of AURKA and AURKB will significantly decrease the expression of EMT drivers and reduce the cells' ability to invade. TCGA data suggests a significant overexpression of AURKA and AURKB in breast cancer. Kaplan-Meier analysis indicates that overexpression of AURKA and AURKB is associated with a worse relapse-free survival rate compared to women who have normal expression. After performing the siRNA-mediated knockdown, MTT assay, immunoblotting, immunofluorescence, and invasion assays were performed. MTT data demonstrate that co-targeting AURKA and AURKB decrease cell viability; but most cells still proliferate. Immunoblotting data suggests that co-targeting AURKA and AURKB significantly decreases SNAIL expression in MDA-MB-157 (NHB), while immunofluorescence data indicate a decrease in Beta-catenin expression in both cell lines. Moreover, co-targeting AURKA and AURKB in both cell lines results in a significant reduction in the cells' ability to invade. Preliminary results in MDA-MB-231 (NHW) also suggest a decrease in the invasion capacity after a single knockdown of SNAIL1. Thus, this indicates that AURKA and AURKB can form a specific axis between beta-catenin and SNAIL1 in TNBC. As a future direction, we will use chemical inhibitors in combination to evaluate the expression of these EMT biomarkers. In addition, we will study tumour growth and metastasis rates in vivo models. In conclusion, since treatment options are limited in TNBC, our results suggest that combined targeting of AURKA and AURKB may be a potential approach to decrease the metastatic phenotype of TNBC while lowering the dose of each drug and thus the toxicity in patients.