Increased expression of MyD88 and association with paclitaxel resistance in breast cancer.

MyD88 was reported to be associated with paclitaxel sensitivity in lung cancer; however, its roles in breast cancer remain unclear. The objective of this study is to investigate the expression and function of MyD88 in breast cancer. Immunohistochemistry (IHC) was used to analyze the expression of MyD88 in both breast cancer tissues and adjacent normal tissues. Real-time PCR and Western blots were further used to measure the messenger RNA (mRNA) and protein expression. The proliferation was assessed by WST-1. Flow cytometry was used to measure the cell cycle and apoptosis. The transwell assay was used to observe the change of migration and invasion of transfected cells. In breast cancer tissues, the expression of MyD88 was significantly higher than that in tumor-adjacent normal tissues (P < 0.001). MyD88 expression was found to be associated with the differentiation stages (P = 0.019). Kaplan-Meier survival curves showed statistically significant difference on survival in patients with high expression of MyD88 compared with those with normal expression of MyD88 (P = 0.018). Knockdown of MyD88 reduced the proliferation, migration, and invasion of MCF-7 cells and increased the sensitivity of MCF-7 cells to paclitaxel treatment through the inhibition of activation of NF-κB via PI3K/Akt. Our data indicate that MyD88 may be a potential target molecule to be used in diagnosis and treatment of breast cancer.