Arjunolic acid from Rhodomyrtus tomentosa suppresses growth of non-small cell lung cancer via inducing autophagy and apoptosis

Abstract

Introduction

non‑small cell lung cancer (NSCLC), a kind of lung cancer (LC), led to a large number of cancer-related deaths. Rhodomyrtus tomentosa (R. tomentosa), a traditional Chinese medicine, has proven to possess potential inhibitory activities in NSCLC, but the active material basis and possible mechanism remain unclear. This study aims to clarify the active compound from R. tomentosa and the mechanism of that inhibits NSCLC.

Methods

To clarify the anti-NSCLC material basis of R. tomentosa, a bioassay-guided fractionation of the ethanolic extract of R. tomentosa was performed. The anticancer effects were evaluated through in-vitro and in-vivo models, and the cell viability and the levels of PARP cleavage were measured through MTT assays, flow cytometry, and western blot assays. The core target was recognized by Network pharmacology analysis and further confirmed by western blot and molecular docking experiments.

Results

As a result, an active compound, Arjunolic acid (AA), was isolated from the anti-NSCLC fraction which repressed the proliferation and migration of A549, PC9, and H1975 cell lines in a dose- and time-dependent manner. AA exhibited the most potent inhibition of cell viability in PC9 cells for 24 and 48 h (IC₅₀ = 199.0 ± 7.47, 120.8 ± 6.72 μM) and in A549 cells for 72 h (IC₅₀ = 65.06 ± 18.33 μM). Moreover, AA induced apoptosis and autophagy in three NSCLC cell lines and also effectively suppressed tumor growth in the Lewis lung cancer (LLC) tumor-bearing C57BL/6 mice. AA-induced apoptosis is associated with increased levels of PARP cleavage. Additionally, AA could induce autophagy through the downregulation of p62 and upregulation of LC3 Ⅱ/I ratio. Network pharmacology analysis indicated that IL-6 might be a core target of AA in the treatment of NSCLC.

Discussion

These data reveal that AA exerts anti-NSCLC effects by inducing apoptosis and autophagy which may be associated with the expression of IL-6 protein.