Naringin Potentiates Docetaxel-Induced Apoptosis in Breast Cancer Cells via Transient Interaction with the TUBB3 GTP-Binding Site

Breast Cancer (BC) is associated with the overexpression of tubulin isotypes, promoting malignant progression and poor prognosis in patients. Docetaxel (DTX) is a microtubule-targeting agent used in Cancer treatment and has been combined with natural compounds to improve the efficacy; however, limited studies have implicated a direct involvement of Flavanols in disrupting microtubule dynamic instability and cell sensitisation against DTX. In our study, we assessed the effect of the DTX and naringin (NRG) drug combination in breast Cancer and explored a potential direct interaction of NRG with tubulin isotypes. Hence, molecular dynamic simulation and bio-layer interferometry (BLI) were performed to assess the affinity of NRG to TUBB3. The anti-tumour effect of the DTX and NRG drug combination in BC was evaluated using various assays, including the alkaline comet assay and immunofluorescence assay. Additionally, DNA replication and the cell cycle were evaluated by western blot and FACS. The results indicated that NRG had a higher binding affinity toward tubulin isotypes, possessing a transient binding affinity to TUBB3, i.e., it exhibited a rapid association rate toward TUBB3 and increased the soluble tubulin (tubulin dimers) in the cell, which subsequently elevated DTX-induced microtubule polymerisation, cell cycle arrest, and DNA damage. Moreover, the expression of vital DNA replication and cell cycle regulatory proteins was drastically suppressed in the DTX-NRG combination. The study demonstrated that naringin enhanced the sensitivity of DTX in BC cells by directly interacting with TUBB3. These findings in our study provide a breakthrough insight into the GTP-binding site as a potential therapeutic modality to enhance the efficacy of microtubule-targeting agents.

Breast Cancer; Docetaxel; Drug combination; Naringin; TUBB3.