BACKGROUND:Lycium barbarum polysaccharide has many biological activities and has been found to have potential effects on promoting wound healing. OBJECTIVE:To investigate the mechanism of lycium barbarum polysaccharide in tumor necrosis factor-α-mediated keratinocyte apoptosis and its effect on the healing of burn wounds. METHODS:(1)In vitro experiment:Keratinocytes were divided into four groups:cells were cultured in the α-MEM medium(complete medium)containing 15%fetal bovine serum and 1%glutamine in normal group,cultured in the complete medium containing lycium barbarum polysaccharide in positive control group,cultured in the complete medium containing tumor necrosis factor-α in model group,and cultured in the complete medium containing lycium barbarum polysaccharide and tumor necrosis factor-α in experimental group.After 24 hours of culture,cell proliferation was detected using cell counting kit-8 assay;Cleaved caspase-8,TNF R1,FADD,and LC3 were detected using western blot.Then an autophagy inhibitor group(the complete medium containing 3-methyladenine)and an autophagy inhibitor+lycium barbarum polysaccharide group(the complete medium containing lycium barbarum polysaccharide,tumor necrosis factor-α,and 3-methyladenine)were set up.After 24 hours of culture,keratinocyte apoptosis was detected by flow cytometry.(2)In vivo experiment:Six Sprague-Dawley rats were randomly divided into a control group and an experimental group,with three rats in each group.Four deep Ⅱ degree burn wounds with a diameter of 2 cm were made on the back of each rat.At 24 hours after modeling,mice in the control and experimental groups were coated with normal saline and lycium barbarum polysaccharide solution,respectively,once a day.Wound healing was observed regularly after treatment.Samples were taken 28 days after treatment and the pathologic pattern of the wound was observed. RESULTS AND CONCLUSION:(1)In vitro experiment:Addition of lycium barbarum polysaccharide alone did not affect cell proliferation and apoptosis and the expression of apoptotic and autophagic proteins in keratinocytes.After the addition of tumor necrosis factor α,the proliferation of keratinocytes was inhibited,the apoptotic rate increased,and the expression of apoptotic and autophagic proteins was elevated,while lycium barbarum polysaccharide could antagonize the above effects of tumor necrosis factor-α.Lycium barbarum polysaccharide combined with autophagy inhibitors further reduced the apoptotic rate of keratinocytes.(2)In vivo experiment:The wound healing rate of rats in the experimental group was higher than that of the control group at 12,16,20,24,and 28 days after treatment(P＜0.05,P＜0.01).Hematoxylin-eosin staining results at 28 days after treatment showed an intact and well-defined epidermis of the wound in the experimental group compared with the control group.To conclude,lycium barbarum polysaccharide protects the integrity of skin epidermal tissue and promotes wound healing by inhibiting autophagy and apoptosis of keratinocytes.

BACKGROUND:Clinical treatment for colon cancer mainly includes fluorouracil,irinotecan and oxaliplatin-based therapy.Studies have shown that membrane transport proteins such as ATP-binding cassette transport protein of G2(ABCG2)mediate the transport of these drugs.However,when patients develop resistance to these chemotherapeutic drugs,the high expression of ABCG2 leads to a significant decrease in the therapeutic effect and raises the problem of drug resistance in colon cancer.New drugs and treatments are urgently needed to improve the efficacy.Lycium barbarum polysaccharide has a wide range of biological activities.It can be used as anti-tumor drug to overcome the damage to normal cells in the process of chemotherapy and radiotherapy in tumor patients. OBJECTIVE:To explore the reversal effect of Lycium barbarum polysaccharide in combination with oxaliplatin on colon cancer drug-resistant cells through in vitro experiments to investigate the possible molecular mechanism of Lycium barbarum polysaccharide reversal on colon cancer drug-resistant cells. METHODS:Colon cancer cell line HCT116 and oxaliplatin-resistant cell line HCT116-OXR were selected for in vitro experiments.The optimal intervention concentration and intervention time of Lycium barbarum polysaccharide and oxaliplatin were determined by CCK8 assay of cell proliferation.Samples were further divided into the HCT116 control group,HCT116-OXR blank treatment group,Lycium barbarum polysaccharide group(2.5 mg/mL Lycium barbarum polysaccharide),and oxaliplatin group(10 μmol/L oxaliplatin),and Lycium barbarum polysaccharide + oxaliplatin group(2.5 mg/mL Lycium barbarum polysaccharide +10 μmol/L oxaliplatin).Cell apoptosis was detected by flow cytometry.The protein expression levels of phosphomannose isomerase(PMI)and ABCG2 were detected by immunofluorescence and western blot assay.Phosphatidylinositol3-kinase(PI3K),protein kinase B(AKT),B-cell lymphoma 2(Bcl-2)and BCL2-Associated X(Bax)were detected by western blot assay. RESULTS AND CONCLUSION:(1)HCT116-OXR was more sensitive to Lycium barbarum polysaccharide compared to HCT116(P<0.05).(2)Compared with the HCT116-OXR blank group,Lycium barbarum polysaccharide + oxaliplatin could promote apoptosis of HCT116-OXR cells(P<0.05).The protein expression of Bcl-2 was significantly down-regulated(P<0.05);the protein expression of Bax was significantly up-regulated(P<0.05);the protein expression of ABCG2,PMI,PI3K and AKT was significantly down-regulated(P<0.05).(3)These results indicate that Lycium barbarum polysaccharide reverses drug resistance in colon cancer by inhibiting PMI/PI3K/AKT signaling pathway,which lays the foundation for studying the molecular mechanism of Lycium barbarum polysaccharide's sensitizing chemotherapeutic effects.