Induction of cytoprotective autophagy by morusin via AMP-activated protein kinase activation in human non-small cell lung cancer cells

Abstract

BACKGROUND/OBJECTIVES: Morusin, a marker component of Morus alba L., possesses anticancer activity. The objective of this study was to determine autophagy-inducing effect of morusin in non-small cell lung cancer (NSCLC) cells and investigate the underlying mechanism. SUBJECTS/METHODS: Autophagy induction and the expression of autophagy-related proteins were analyzed by LC3 immunofluorescence and western blot, respectively. The role of autophagy and AMP-activated protein kinase (AMPK) was determined by treating NSCLC cells with bafilomycin A1, an autophagy inhibitor, and compound C, an AMPK inhibitor. Cytotoxicity and apoptosis induction were determined by MTT assay, trypan blue exclusion assay, annexin V-propidium iodide (PI) double staining assay, and cell cycle analysis. RESULTS: Morusin increased the formation of LC3 puncta in the cytoplasm and upregulated the expression of autophagy-related 5 (Atg5), Atg12, beclin-1, and LC3II in NSCLC cells, demonstrating that morusin could induce autophagy. Treatment with bafilomycin A1 markedly reduced cell viability but increased proportions of sub-G1 phase cells and annexin V-positive cells in H460 cells. These results indicate that morusin can trigger autophagy in NSCLC cells as a defense mechanism against morusin-induced apoptosis. Furthermore, we found that AMPK and its downstream acetyl-CoA carboxylase (ACC) were phosphorylated, while mammalian target of rapamycin (mTOR) and its downstream p70S6 kinase (p70S6K) were dephosphorylated by morusin. Morusin-induced apoptosis was significantly increased by treatment with compound C in H460 cells. These results suggest that morusin-induced AMPK activation could protect NSCLC cells from apoptosis probably by inducing autophagy. CONCLUSIONS: Our findings suggest that combination treatment with morusin and autophagy inhibitor or AMPK inhibitor might enhance the clinical efficacy of morusin for NSCLC.

Antitumor Effect of Morusin via G1 Arrest and Antiglycolysis by AMPK Activation in Hepatocellular Cancer

“…Notably, compound K suppressed glycolysis in hepatocellular cells [ 38 ], and Lapachol inhibited glycolysis in melanoma cancer cells [ 39 ]. Moreover, Morusin induced autophagy in lung cancer cells by activating AMPK [ 40 ].…”

Targeting Autophagy with Natural Products as a Potential Therapeutic Approach for Cancer

“…Morusin has been highlighted for its versatile potential against human pathologies, including cancer and immune dysfunctions. Morusin treatment leads to mTOR1 inhibition and the subsequent activation of AMPK, resulting in ULK1-mediated autophagy activation [ 135 , 136 ]. Naringin inhibits human gastric carcinoma, via the induction of autophagy, by activating Beclin1 and LC3-II via the activation of MAPKs pathways [ 243 ].…”

Apoptotic and anti‐Warburg effect of Morusin via ROS mediated inhibition of FOXM1/c‐Myc signaling in prostate cancer cells

“…In the same line, though Morusin isolated from Morus alba was reported to exhibit antitumor effect in colon (Zhou et al, 2021), liver (Cho et al, 2021), lung (Park & Park, 2020), stomach (Wang et al, 2017), ovarian (Xue et al, 2018), glioblastoma (Park et al, 2016), prostate (Lim et al, 2015), and pancreas (Kim et al, 2016) cancers with apoptotic, antiprolifertaive, and autophagic mechanisms through several signaling pathways, the underlying molecular mechanisms of Morusin still remain unclear until now. Hence, in the current work, the apoptotic mechanism of Morusin was examined in prostate cancer cells in connection with ROS/FOXM1/c-Myc signaling axis.…”