Thidiazuron suppresses breast cancer via targeting miR-132 and dysregulation of the PI3K-Akt signaling pathway mediated by the miR-202-5p-PTEN axis.

Chemo-resistance and metastasis are the most common causes of breast cancer recurrence and death. Thidiazuron (TDZ) is a plant growth regulator (phytohormone) whose biological effects on humans and animals has not yet been determined. In this study, we investigated the anticancer activity of this phytohormone on the drug resistant-triple negative breast cancer cell line MDA-MB-231. Treatment of the breast cancer cells with TDZ (1-50 μmol/L) caused more stressful environment and induced a significant increase in active caspase-positive cells. In addition, TDZ treatment (5 and 10 μmol/L) significantly attenuated the migration and the invasiveness of these highly metastatic cancer cells. Mechanistically, TDZ reduces cancer progression and invasiveness by targeting miR-202-5p, which stimulates the expression of phosphatase and tensin homolog (PTEN), the tumor suppressor that downregulates the PI3K-Akt signaling pathway. Treatment with TDZ significantly upregulates miRNA-132, the suppressor of breast cancer proliferation, which is also implicated in dysregulation of the TEN-Akt-NFκB signaling pathway. Interestingly, our molecular docking analysis revealed a potential non-covalent interaction between TDZ and Akt, PTEN, and PI3K. These findings suggest that TDZ suppresses breast cancer metastasis by targeting miRNA-132, the miR-202-5p-PTEN axis, and the PI3K-Akt signaling pathway downstream.