[Effect of Src tyrosine kinase inhibition on the drug-resistance as well as MDR1 and LRP expression of the human cis-platinum-resistant lung cancer cell line A549/DDP]

Hesperetin reverses P‑glycoprotein‑mediated cisplatin resistance in DDP‑resistant human lung cancer cells via modulation of the nuclear factor‑κB signaling pathway

Lung cancer is the leading cause of cancer-associated mortality worldwide. Cisplatin (DDP) is a first-line chemotherapeutic drug for the treatment of lung cancer; however, the majority of patients develop resistance to DDP. P-glycoprotein (P-gp), also referred to as multidrug resistance (MDR) protein 1, is associated with an MDR phenotype, which results in failure of cancer chemotherapy; thus, identifying effective MDR pump inhibitors may improve the outcomes of patients who develop resistance to treatment. Hesperetin is a derivative of hesperidin, which is extracted from tangerine peel and exhibits multiple antitumor properties. In the present study, human lung adenocarcinoma A549 and A549/DDP cells were treated with different concentrations of hesperetin and DDP, respectively. Furthermore, rhodamine 123 efflux assays, Cell Counting Kit-8 assays, immunofluorescence, reverse transcription-quantitative PCR and western blot analysis were used to elucidate the mechanisms underlying the effects of hesperetin On A549/DDP cells. Additionally, a xenograft model of lung cancer in nude mice was established to explore the effects of hesperetin on A549/DDP cell growth in vivo. The results demonstrated that hesperetin sensitized A549/DDP cells to DDP. In vivo, hesperetin pretreatment significantly inhibited tumor growth. Mechanistically, hesperetin markedly decreased the expression of P-gp and increased the intracellular accumulation of the P-gp substrate, rhodamine 123, in A549/DDP cells. In addition, pretreatment of A549/DDP cells with hesperetin significantly inhibited nuclear factor (NF)-κB (p65) activity and its nuclear translocation. Taken together, the results of the present study suggest that hesperetin reversed P-gp-mediated MDR by decreasing P-gp expression in A549/DDP cells, which was associated with inhibition of the NF-κB signaling pathway. These findings may provide the basis for the use of hesperetin clinically to reverse MDR.

β-elemene reverses the drug resistance of A549/DDP lung cancer cells by activating intracellular redox system, decreasing mitochondrial membrane potential and P-glycoprotein expression, and inducing apoptosis

BACKGROUND

β-elemene (β-ELE) injection is a new anticancer drug extracted from Curcuma zedoaria Roscoe that has been widely used to treat malignant tumors. Recent studies show that β-ELE reverses the drug resistance of tumor cells. To explore the possible mechanisms of β-ELE, we investigated its effects on cisplatin (DDP)-resistant human lung adenocarcinoma A549/DDP cells.

METHODS

The effects of β-ELE on the growth of A549/DDP cells in vitro were determined by MTT assay. Apoptosis was assessed by fluorescence microscopy with Hoechst 33258 staining, flow cytometry with Annexin V-FITC/propium iodide double staining; mitochondrial membrane potential using JC-1 fluorescence probe and laser confocal scanning microscopy, and intracellular reactive oxygen species levels were measured by 2',7'-dichlorfluorescein-diacetate staining and flow cytometry; and contents of cytosolic glutathione were determined by glutathione assay kits. Intracellular Rhodamine-123 fluorescence intensity was detected by flow cytometry, and the expression of P-glycoprotein (P-gp) was detected by Western blotting.

RESULTS

β-ELE inhibited the proliferation of A549/DDP cells in a time- and dose-dependent manner. Furthermore, β-ELE enhanced the sensitivity of A549/DDP cells to cisplatin and reversed the drug resistance of A549/DDP cells. Consistent with a role in activating apoptosis, β-ELE decreased mitochondrial membrane potential, increased intracellular reactive oxygen species concentration and intracellular accumulation of Rhodamine-123, decreased the cytoplasmic glutathione levels and the expression of P-gp in a time- and dose-dependent manner.

CONCLUSIONS

These results define a pathway of β-ELE function that involves decreased mitochondrial membrane potential and P-gp expression activated intracellular redox system, and induced apoptosis leading to reverse drug resistance.