Muyin extract inhibits non-small-cell lung cancer growth by inducing autophagy and apoptosis in vitro and in vivo

Abstract

Background: Non-small cell lung cancer (NSCLC) is a major subtype of lung cancer with a higher mortality rate. Both apoptosis and autophagy are crucial processes in the pathophysiology of NSCLC. Muyin extract (MSE) is a combination of Momordica cochinchinensis (Lour.) Spreng seeds and Epimedium brevicornu Maxim extract, with an optimal ratio of 1:1. Our previous research has firstly shown that MSE exerts a good anti-tumor activity, especially for NSCLC.

Purpose: This study aims to evaluate the inhibitory effect of MSE on NSCLC and explore the underlying mechanism.

Methods: In vitro, cell proliferation was examined by MTT and colony formation. Apoptosis was detected by annexin V-FITC/PI assay while autophagy was assessed by Acridine orange (AO) and Monodansylcadaverine (MDC) staining. In vivo, Lewis lung cancer cell transplanted mice model was established to measure the effect of MSE on tumor growth. Hematoxylin eosin (H & E) staining was used to observe the pathological changes of the tumor after MSE treatment. The apoptosis in tumor tissue was detected by TUNEL assay. Meanwhile, the cellular proliferation marker Ki67 and autophagy marker LC3Ⅱ were observed by immunohistochemistry staining. The IL-4 and IFN-γ concentrations in blood were tested by Elisa. The apoptosis related factors (Bcl-2, Bax Caspase-3, cleaved Caspase-3, Caspase-9 and p53), autophagy marker proteins (Atg-5, Becline-1, LC3Ⅱ/Ⅰand p62) as well as Akt/mTOR pathway were detected by western blotting.

Results: Present study showed that MSE greatly inhibited the proliferation of NSCLC in vitro and in vivo, together with apoptotic rate increasing. P53 and cleaved Caspase-3 levels were up-regulated while Bcl-2/Bax ratio, Caspase-3 and Caspase-9 levels were significantly down-regulated treated with MSE. Meanwhile, MSE activated autophagy, Atg-5, Becline-1 as well as the ratio of LC3Ⅱ/Ⅰ were notably up-regulated while p62 was down-regulated after MSE treatment. Importantly, MSE significantly blocked Akt/mTOR pathway, which is a common upstream signal triggered by autophagy and apoptosis. Furthermore, when co-treated with specific autophagy inhibitor, the inhibitory rate and anti-apoptotic Bcl-2 level were significantly reversed. Impressively, MSE remarkably increased IFN-γ/ IL-4 ratio while VP16 did not in animal model, and the inhibition rate in tumor weight after MSE treatment was higher than xiaojin pill.

Conclusion: Taken together, it is proved that MSE may be a promising oral TCM candidate for NSCLC therapy with immunity improvement. The underlying mechanisms could be associated with the induction of apoptosis and autophagy through blocking Akt/mTOR pathway, meanwhile, it may promote crosstalk between autophagy and apoptosis.

Keywords: Apoptosis; Autophagy; Epimedium brevicornu Maxim; Momordica cochinchinensis (Lour.) Spreng seeds; Muyin extract; NSCLC.