Centipeda minima extracts and the active sesquiterpene lactones have therapeutic efficacy in non-small cell lung cancer by suppressing Skp2/p27 signaling pathway

Ethnophamacological relevance: Centipeda minima (L.) A. Braun & Asch (C. minima) was applied to treat nasal allergy, headache, cough, and even nasopharyngeal carcinoma in traditional Chinese medicine. However, the underlying anticancer mechanisms of C. minima and its active components have not been systematically illustrated.

Aim of the study: The study aims to examine the therapeutic efficacy of the ethanol extract of C. minima (ECM) and its active components in non-small cell lung cancer (NSCLC) and illustrate the underlying mechanisms.

Materials and methods: The main chemical components in the ethanol extract of C. minima (ECM) and the supercritical CO₂ fluid extract of C. minima (CM-SFE) were determined by using ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). The antitumor effects of ECM and CM-SFE were examined by using NSCLC cell xenografts. The flow cytometry, cell colony formation, wound-healing, transwell assay, and Western blotting were conducted to investigate the anticancer properties of ECM, CM-SFE, and these sesquiterpene lactones that abundantly distributed in these extracts.

Results: We first determined that ECM contains high levels of sesquiterpene lactones. ECM can markedly induce cell cycle arrest and suppress migration and invasion of NSCLC cells. Mechanistically, ECM promoted proteasome-dependent degradation of Skp2 protein and induced the accumulation of its substrates p27; whereas Skp2 overexpression can attenuate the inhibitory effects of ECM on NSCLC proliferation and migration. Moreover, ECM at 200-600 mg/kg can significantly inhibit tumor growth and metastasis in A549-luciferase cell orthotopic xenografts by suppressing Skp2 expression. The sesquiterpene lactones that abundantly distributed in ECM, including 6-O-angeloylplenolin (6-OAP), arnicolide D (ArD) and arnicolide C (ArC), were also demonstrated to decrease Skp2 while increase p27 protein level, thereby significantly inducing cell cycle arrest and suppressing migration of NSCLC cells. Notably, CM-SFE, which mainly consisted of 6-OAP, ArD and ArC, exhibited much stronger anti-NSCLC activity than that of ECM in A549-luciferase cell orthotopic xenografts.

Conclusion: Our results demonstrate that the active components in C. minima possesses potential anti-NSCLC activities by suppressing Skp2/p27 signaling pathway, and these active sesquiterpene lactones can be further developed as potent Skp2 inhibitor to treat NSCLC.