The superiority of PMFs on reversing drug resistance of colon cancer and the effect on aerobic glycolysis-ROS-autophagy signaling axis

Background:Polymethoxylatedflavones(PMFs)are compounds present in citrus peels and other Rutaceae plants,which exhibit diverse biological activities,including robust antitumor and antioxidant effects.However,the mechanism of PMFs in reversing drug resistance to colon cancer remains unknown.In the present study,we aimed to investigate the potential connection between the aerobic glycolysis-ROS-autophagy signaling axis and the reversal of PTX resistance in colon cancer by PMFs.Methods:MTT Cell viability assay and colony formation assay were used to investigate the effect of PMFs combined with PTX in reversing HCT8/T cell resistance ex vivo;the mRNA and protein levels of the target were detected by SDS-PAGE(sodium dodecyl sulfate-polyacrylamide gel electrophoresis),quantitative real-timefluorescence polymerase chain reaction(qRT-PCR)and Western blot protein immunoblotting(WB);An HCT8/T cell xenograft model was established to investigate the MDR reversal activity of PMFs in vivo;The extracellular acidification rate(ECAR)and the oxygen consumption rate(OCR)were detected to assess the cellular oxygen consumption rate and glycolytic process.Results:HCT8/T cells demonstrated significant resistance to PTX,up-regulating the expression levels of ABCB1 mRNA,P-gp,LC3-I,and LC3-II protein,and increasing intracellular reactive oxygen species(ROS)content.PMFs mainly contain two active ingredients,nobiletin,and tangeretin,which were able to reverse drug resistance in HCT8/T cells in a concentration-dependent manner.PMFs exhibited high tolerance in the HCT8/T nude mouse model while increasing the sensitivity of PTX-resistant cells and suppressing tumor growth significantly.PMFs combined with PTX reduced extracellular acidification rate(ECAR)and oxygen consumption rate(OCR)in HCT8/T cells.Additionally,PMFs reduced intracellular ROS content,down-regulated the expression levels of autophagy-related proteins LC3-I,LC3-II,Beclin1,and ATG7,and significantly reduced the number of autophagosomes in HCT8/T cells.Conclusions:The present study demonstrated that PMFs could potentially reverse PTX resistance in colon cancer by regulating the aerobic glycolysis-ROS-autophagy signaling axis,which indicated that PMFs would be potential potentiators for future chemotherapeutic agents in colon cancer.

柑桔果皮中多甲氧基黄酮的LC-APCI-MS定性分析

黄酮化合物是具有多种生物活性的物质,广泛存在于自然界中.单纯为甲氧基取代的多甲氧基黄酮PMF是芸香科多种桔类所特有的,特别是在其果皮中有较高的含量.近年来有关桔皮PMF抗癌的研究取得了很大进展.PMF作为桔皮中的抗癌活性成分,对多种癌细胞有较强的抑制作用,受到国内外的广泛关注.……

5-Acetyl-6,7,8,4′-tetramethylnortangeretin induces apoptosis in multiple myeloma U266 cells

Multiple myeloma(MM)is one of the most common hematological malignancies and to date,it remains an incurable disease.In this study,we evaluated the inhibitory effect of 5-acetyloxy-6,7,8,4′-tetramethoxyflavone(5-ATMF),a compound from aged citrus peel extracts,on the MM U266 cell line.We found that the compound inhibited cell growth and induced cell apoptosis in multiple apoptotic assays.The apoptotic proteins caspase-3,caspase-9,and PARP(poly ADP-ribose polymerase)were cleaved when cells were treated with 5-ATMF.Along with the apoptosis process,the anti-apoptotic protein,Bcl-2(B-cell lymphoma-2),was significantly downregulated and the pro-apoptotic protein,Bax(Bcl-2 associated X protein),upregulated along with the release of cytochrome C(Cyt c)and the reduction of mitochondrial membrane potential(MMP).Notably,we found that the phosphorylation of Bad(Bcl-2/Bcl-XL-associated death promoter)was decreased but Bad remained unchanged in this process.On adding 5-ATMF to U266 cells,we observed that 5-ATMF repressed the phosphorylation of Akt(PKB Protein Kinase B PKB),thereby increasing the release of Cyt c and inhibiting the phosphorylation of Bad.These effects were enhanced by Ly294002,an inhibitor of Akt.These results suggested that 5-ATMF exerts a pro-apoptotic effect on U266 cells,possibly associated with the mitochondrial apoptotic pathway induced by the PI3K/Akt/Bad pathway.

Nobiletin and tangeretin(citrus polymethoxyflavones): an overview on their chemistry, pharmacology and cytotoxic activities against breast cancer

The fruit peel of Citrus species(Chenpi),particularly those of mandarin oranges,is a useful source of food and medicine in China.Flavonoids from the citrus fruit peel are mainly polymethoxyflavones(PMFs),of which nobiletin and tangeretin are the most abundant components.In the present review,we summarized the cytotoxic activities of these two PMFs to breast cancer cells.Studies have reported that these two compounds inhibit the growth of breast cancer cells by inducing apoptosis,cytostatic cell death and cell cycle arrest,or by inhibiting cell proliferation,metastasis and tumour angiogenesis,depending on the molecular subtypes of breast cancer.In vitro and in vivo cytotoxic activities involve different molecular targets and signalling pathways.Analyses on the structure-activity relationship(SAR)of nobiletin and tangeretin have shown that the presence of a methoxy group at C8 and a hydroxyl group at C3 or C5 are essential for anti-proliferative activity.Some future perspectives and research needs are suggested.Sources of information are from Pub Med,Pub Med Central,Science Direct,Google Scholar,J-Stage,Pub Chem and CNKI using keyword search.