Effect Of Dendrobium Officinalis On Autophagy And Tumor Suppressor Gene Expression In Nude Mouse Xenograft Of Lung Adenocarcinoma

Objective: The inhibitory effect of dendrobium officinalis on human lung adenocarcinoma xenograft and its mechanism were studied in nude mice.Methods: 1,The cells were cultured and identified by HE staining and immunohistochemical staining.2,Establishment and experimental study of A549 lung adenocarcinoma xenograft model in nude mice: nude mice were randomly divided into 6 groups,including blank control group,negative control group(model group),positive control group(cyclophosphamide group,CTX group),dendrobium officinalis low concentration group,dendrobium officinalis medium concentration group,and dendrobium officinalis high concentration group.Nude mice blank control group and the negative control group normal saline lavage(30 ml/kg),intraperitoneal injection of cyclophosphamide group dosage(every other day,0.025 g/kg),the concentration of low concentration dendrobium officinalis,medium dendrobium officinalis,high concentration of dendrobium officinalis each day to 6.25 g / kg,12.5 g/kg,25 g/kg lavage,during the period of drug delivery,measuring tumors had once every other day.The day after the drug was stopped,the nude mice were sacrificed,and the tumor body was weighed and measured before use.3,Histopathological changes of transplanted tumor tissues in each group were observed by HE staining.Immunohistochemistry was used to observe the effect of dendrobium officinale on the protein expression of autophagy related factor Beclin1 and proliferation index Ki67 in transplanted tumor tissues of nude mice.RT-PCR was used to detect the effects of dendrobium officinale on the expression of tumor suppressor genes p53,p16 and EGFR in transplanted tumor tissues of nude mice.Results: 1.The human lung adenocarcinoma cell lines were identified and the A549 lung adenocarcinoma xenograft mouse model was successfully established.2.Compared with the negative control group(model group),the drugs in the positive control group and the low,medium and high concentration dendrobium officinalis group all slowed down the growth of transplanted tumor in nude mice and reduced the tumor volume,and the difference was statistically significant(P<0.05).The tumor inhibition rates of cyclophosphamide group and low,medium and high 3.concentrations reached 62%,51%,52% and 56%,respectively,and showed a dose-dependent relationship.3.Immunohistochemical results showed that,compared with the negative control group,Beclin1 positive expression rate of dendrobium officinale with medium concentration,dendrobium officinale with high concentration and positive control group gradually increased,while Ki67 positive rate of dendrobium officinale with high concentration and positive control group gradually decreased.RT-PCR results showed that compared with the negative control group,the EGFR m RNA levels in the transplanted tumor tissues of nude mice in the medium and high concentration dendrobium officinale groups were down-regulated,and the difference in the high concentration dendrobium officinale group was statistically significant(P<0.05).The levels of p53 and p16 m RNA in transplanted tumor tissues of nude mice in dendrobium officinalis group were up-regulated.Among them,compared with the negative control group,the difference of p16 m RNA in transplanted tumor tissues of nude mice treated with dendrobium officinale at medium concentration and high concentration was statistically significant(P<0.05).The differences of p53 m RNA in transplanted tumor tissues of nude mice in dendrobium officinale group at different concentrations were statistically significant(P<0.05).Conclusions: Dendrobium officinale inhibited the growth of transplanted tumor tissue in nude mice with lung adenocarcinoma A549 cells,and its mechanism may be related to the up-regulation of autophagy related factor Beclin1 and the expression of tumor suppressor genes p16 and p53,and the down-regulation of EGFR.Apoptosis may be induced by initiating autophagy.