---

RA-XII, a bicyclic hexapeptidic glucoside isolated from Rubia yunnanensis Diels, exerts antitumor activity by inhibiting protective autophagy and activating Akt-mTOR pathway in colorectal cancer cells

作者 Wang, Jing; Wang, Jia; Li, Ling; Feng, Li; Wang, Yu-Rong; Wang, Zhe; Tan, Ning-Hua

期刊 JOURNAL OF ETHNOPHARMACOLOGY , FEB 10 2021,:266

DOI 10.1016/j.jep.2020.113438 PubMed 33017635

摘要 Ethnopharmacological relevance: The roots of Rubia yunnanensis Diels (Chinese name ''Xiao-Hong-Shen''), a traditional Chinese medicine native to Yunnan province (China), have a long history of use for treating several diseases, such as tuberculosis, rheumatism and cancers. A bicyclic hexapeptidic glucoside named RA-XII was isolated from R. yunnanensis, which has been reported to exert anti-inflammatory and antitumor activities.Aim of the study: This study was designed to investigate the antitumor activity and potential mechanism of RA-XII on colorectal cancer (CRC) cell lines.Materials and methods: Sulforhodamine B assay, clonogenic assay and cell cycle analysis were conducted to assess the anti-proliferative activity of RA-XII on CRC cells. GFP-LC3B plasmid transfection, MDC and AO staining assays, cathepsin activity assay, and siRNAs against several genes were used to investigate the effect of RA-XII on autophagy. Western blotting was used to examine the expression levels of proteins associated with cell cycle arrest, apoptosis and autophagy. Human CRC xenograft-bearing BALB/c nude mice were used to evaluate the antitumor effect of RA-XII in vivo.Results: RA-XII showed favorable antineoplastic activity in SW620 and HT29 cells in vitro and in vivo. RA-XII did not induce apoptosis indicated by no obvious changes on mitochondrial membrane potential and apoptosisrelated marker proteins in SW620 or HT29 cells. Treatment of RA-XII inhibited the formation of autophagosomes, which is implied by the GFP-LC3 fluorescent dots, MDC-stained autophagic vesicles and LC3 protein expression. It was indicated that RA-XII suppressed autophagy by regulating several signaling pathways including mTOR and NF-kappa B pathways. Pharmacological or genetic inhibition of autophagy could enhance the cytotoxicity of RA-XII while autophagy inducer could rescue RA-XII-induced cell death. Besides, RA-XII could increase the susceptibility of CRC cells to bortezomib.Conclusion: Our study demonstrated that RA-XII exerted antitumor activity independent of apoptosis, and suppressed protective autophagy by regulating mTOR and NF-kappa B pathways in SW620 and HT29 cell lines, which suggested that RA-XII is a key active ingredient for the cancer treatment of Rubia yunnanensis and possesses a promising prospect as an autophagy inhibitor for CRC therapy.

涉及物种 紫参 Rubia yunnanensis