Effect of Astragalus Polysaccharide on EMT of A549/DDP Lung Adenocarcinoma Xenograft： An Exploration Based on PI3K/Akt Signaling Pathway / 中国实验方剂学杂志

ABSTRACT

Objective:To investigate the effect of Astragalus polysaccharide （APS） on transforming growth factor-<italic>β</italic>₁ （TGF-<italic>β</italic>₁）-induced epithelial mesenchymal transition （EMT） of A549/DDP lung adenocarcinoma xenograft and its potential molecular mechanism. Method:BALB/c nude mice were randomly divided into the non-loading group （A549/DDP cells not loaded with TGF-<italic>β</italic>₁）， model group， cisplatin group， and combined group （A549/DDP cells overexpressing TGF-<italic>β</italic>₁）. Mice in the combined group were treated with intragastric administration of APS （0.3 g·kg^-1·d^-1） and intraperitoneal injection of cisplatin （0.003 5 g·kg^-1）， while those in the cisplatin group only received intraperitoneal injection of cisplatin （0.003 5 g·kg^-1）. After drug intervention， the nude mice were sacrificed and the xenograft and lung were harvested， followed by the weighing of tumor and the calculation of the inhibition rate. The number of tumors metastasizing to the lung was counted under the microscope. The pathological features of tumors and their metastasis to the lung tumor were observed by hematoxylin-eosin （HE） staining. The protein and mRNA expression levels of EMT molecular markers E-cadherin， Vimentin， <italic>α</italic>-smooth muscle actin （<italic>α</italic>-SMA）， and phosphatidylinositol 3-kinase/protein kinase B （PI3K/Akt） in the xenograft were detected by immunohistochemistry， Western blot， and Real-time polymerase chain reaction （Real-time PCR）. Result:Compared with the non-loading group， the model group exhibited increased tumor weight and pulmonary metastatic nodules （<italic>P</italic><0.05）， sparse tumor cell junctions， long spindle cells， massive metastatic nodules in the lung， down-regulated E-cadherin protein and mRNA expression， and up-regulated Vimentin and <italic>α</italic>-SMA protein and mRNA expression and p-PI3K and p-Akt protein expression （<italic>P</italic><0.05）. Compared with the model group and cisplatin group， the combined group displayed decreased tumor weight and pulmonary metastatic nodules （<italic>P<</italic>0.05）， tight tumor cell junctions， round or oval cells， no obvious lung metastasis， up-regulated E-cadherin protein and mRNA expression （<italic>P</italic><0.05）， and down-regulated Vimentin and <italic>α</italic>-SMA protein and mRNA expression （<italic>P</italic><0.05） and p-PI3K and p-Akt protein expression （<italic>P</italic><0.05）. There was no significant difference in PI3K or Akt protein expression among groups. Conclusion:APS has a certain inhibitory effect against EMT in lung adenocarcinoma A549/DDP cells， which may be related to the inhibition of activated PI3K/Akt protein expression.