Mechanism of Induction of P-gp Activity During MET Induced by DEX in Lung Cancer Cell Line.

Lung cancer metastasis often leads to a poor prognosis for patients. Mesenchymal-epithelial transition (MET) is one key process associated with metastasis. MET has also been linked to multidrug drug resistance (MDR). MDR arises from the overactivity of drug efflux transporters such as P-glycoprotein (P-gp) which operate at the cell plasma membrane, under the regulatory control of the scaffold proteins ezrin (Ezr), radixin (Rdx), and moesin (Msn), collectively known as ERM proteins. The current study was intended to clarify the functional changing of P-gp and the underlying mechanisms in the context of dexamethasone (DEX)-induced MET in lung cancer cells. We found that the mRNA and membrane protein expression of Ezr and P-gp was increased in response to DEX treatment. Moreover, the DEX-treated group exhibited an increase in Rho123 efflux, and it was reversed by treatment with the P-gp inhibitor verapamil or Ezr siRNA. The decrease in cell viability with paclitaxel (PTX) treatment was mitigated by pretreatment with DEX. The increased expression and activation of P-gp during the progression of lung cancer MET was regulated by Ezr. The regulatory mechanism of P-gp expression and activity may differ depending on the cell status.