Studies On Nobiletin-enhanced Efficacy Of Anticancer Drugs And Its Mechanisms

Nobiletin is one of the citrus polymethoxyflavone and has been shown to exert a widerange of pharmacological activities.In order to provides scientific basis for the research of nobiletin in the field of antitumor and to explores its potential application value,it is important to evaluate the effects of nobiletin alone and in combination with anti-cancer drugs.(1)The effects and mechanism of nobiletin in combination with bicalutamide on VCaP and PC-3 cells were chosen as models to study the effects of nobiletin and bicalutamide on prostate cancer.The cell viability was analyzed by MTT assay and trypan blue exclusion assay.The synergistic action of nobiletin and bicalutamide was confirmed using isobologram analysis.The inhibitory effect of 30?M nobiletin in combination with 30?M bicalutamide on apoptosis,colony formation and migration in VCaP and PC-3 cells were detecting by PI staining,colony formation assay and wound-healing assay,respectively.NF-?B-luciferase reporter gene expression assay was used to analyze the NF-?B activity in VCaP and PC-3 cells.Expression of proteins was determined by Western blot.(2)The effects and mechanism of nobiletin in combination with gemcitabine on PANC-1 cells were chosen as models to study the effects of nobiletin and gemcitabine on pancreatic cancer.Changes in cell proliferation,migration and invasion were analyzed by MTT assay,sphere formation assay,wound-healing assay and Transwell assay.The synergistic action of nobiletin and gemcitabine was confirmed using isobologram analysis.Expression of proteins was determined by Western blot.(1)Nobiletin enhanced the effects of bicalutamide on prostate cancer via down regulation of NF-?B,Erk1/2 and STAT3 activation.Treating the cells with nobiletin and bicalutamide alone significantly inhibit the cell viability in VCaP and PC-3 cells.Combination treatment of nobiletin and bicalutamide produced an enhanced inhibitory effect on the growth of prostate cancer cells,the CI value was<1,cell viability were 86.7% to 29.8% in VCaP and 63.3% to 20.4% in PC-3.Compared to treatment alone group,combination treatment of nobiletin and bicalutamide synergistically inhibited VCaP and PC-3 cells colony formation,migration(% cell motility was 53.7 in VCaP and 58.6 in PC-3)and induced apoptosis(% apoptosis cell were 36.0 in VCaP and 34.2 in PC-3).Mechanistic studies demonstrate that nobiletin and bicalutamide significantly inhibited the expression of NF-?B,p-STAT3,p-Erk1/2,survivin and c-myc.(2)Nobiletin inhibited proliferation,migration,and invasion and enhanced the anti-cancer effect of gemcitabine in pancreatic cancer cells.Nobiletin significantly inhibited the cell viability and sphere formation of PANC-1 cells in a concentration-dependent way,cell viability was 81.6% to 47.2%.Nobiletin significantly inhibited PANC-1 cell migration and invasion via down regulating MMP-2.Wound-healing assay and Transwell assay shown that cell migration were 54.4%-32.6% and 67.7%-35.6%,respectively.The percent of cell invasion were 74.1%-40.8%.The inhibitory effect of nobiletin on PANC-1 cells were related to down regulation of p-STAT3/STAT3 and p-mTOR/mTOR.Furthermore,the combination of nobiletin and gemcitabine synergistically inhibited PANC-1 cell viability(CI<1,cell viability was 56.8%-46.1%)and sphere formation(% of sphere formation were 57.4%-15.9%);mechanistic studies demonstrated that the synergistic inhibition of proliferation was associated with a significant decrease in the expression of p-STAT3.Our results shown that nobiletin enhanced the anti-cancer effect of bicalutamide and gemcitabine in prostate cancer cells and in pancreatic cancer,respectively.Nobiletin may be a promising candidate for prostate and pancreatic cancer adjuvant treatment.