Utilization of a UPLC-MS/MS Approach to Elucidate the Role of ABCB1-Mediated Paclitaxel Resistance in Non-Small Cell Lung Cancer Cells.

[OBJECTIVES] Acquired resistance to paclitaxel represents a critical barrier to the effective chemotherapy of non-small cell lung cancer (NSCLC). The present study aimed to elucidate the molecular and pharmacological mechanisms promoting paclitaxel resistance in NSCLC and to explore potential strategies for overcoming this resistance.

[METHODS] Here, we report an integrated pharmacological and analytical approach to quantify paclitaxel disposition and overcome resistance in a A549/TAX cell model (paclitaxel-resistant A549 cells).

[RESULTS] Cell counting kit-8 (CCK-8) assay, colony formation, and apoptosis assays confirmed that A549/TAX cells exhibited marked resistance to paclitaxel relative to parental A549 cells. Based on transcriptome profiling by RNA sequencing analysis and validation by western blotting assay, we found that the expression of the ATP-binding cassette subfamily B member 1 (ABCB1) (the encoded protein is termed P-glycoprotein) was significantly upregulated in resistant cells. By using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), we demonstrated that ABCB1 overexpression promotes enhanced efflux of intracellular paclitaxel, thereby lowering its cytotoxic accumulation. Genetic silencing of ABCB1 or pharmacological inhibition with the specific P-glycoprotein modulator elacridar or tariquidar restored intracellular paclitaxel levels, as determined by UPLC-MS/MS, and synergistically decreased cell viability as observed in CCK-8 assay.

[CONCLUSION] These findings reveal that the ABCB1-mediated drug efflux is a crucial mechanism underlying paclitaxel resistance in NSCLC cells, with UPLC-MS/MS serving as a sensitive analytical method to detect paclitaxel concentration. Inhibition of ABCB1 is a promising therapeutic strategy to resensitize resistant tumor cells to paclitaxel.