Luteolin enhances drug chemosensitivity by downregulating the FAK/PI3K/AKT pathway in paclitaxel-resistant esophageal squamous cell carcinoma

Drug resistance is a key factor underlying the failure of tumor chemotherapy. It enhances the stem-like cell properties of cancer cells, tumor metastasis and relapse. Luteolin is a natural flavonoid with strong anti-tumor effects. However, the mechanism(s) by which luteolin protects against paclitaxel (PTX)-resistant cancer cell remains to be eluci- dated. The inhibitory effect of luteolin on the proliferation of EC1/PTX and EC1 cells was detected by cell counting kit-8 assay. Colony formation and flow cytometry assays were used to assess clonogenic capacity, cell cycle and apoptosis. Wound healing and Transwell invasion tests were used to investigate the effects of luteolin on the migration and inva- sion of EC1/PTX cells. Western blotting was used to detect the protein levels of EMT-related proteins and stem cell markers after sphere formation. Parental cells and drug-resistant cells were screened by high-throughput sequencing to detect the differential expression of RNA and differential genes. ELISA and western blotting were used to verify the screened PI3K/Akt signaling pathway, key proteins of which were explored by molecular docking. Hematoxylin and eosin staining and TUNEL staining were used to observe tumor xenografts on morphology and apoptosis in nude mice. The present study found that luteolin inhibited tumor resistance (inhibited prolif- eration, induced cell cycle arrest and apoptosis and hindered migration invasion, EMT and stem cell spherification) in vitro in PTX-resistant esophageal squamous cell carcinoma (ESCC) cells. In addition, luteolin enhanced drug sensitivity and promoted the apoptosis of drug-resistant ESCC cells in combination with PTX. Mechanistically, luteolin may inhibit the PI3K/AKT signaling pathway by binding to the active sites of focal adhesion kinase (FAK), Src and AKT. Notably, luteolin lowered the tumorigenic potential of PTX-resistant ESCC cells but did not show significant toxicity in vivo. Luteolin enhanced drug chemosensitivity by downregulating the FAK/PI3K/AKT pathway in PTX-resistant ESCC and could be a promising agent for the treatment of PTX-resistant ESCC cancers.