Guo-Sheng Wu

Anti-cancer natural products isolated from chinese medicinal herbs.

In recent years, a number of natural products isolated from Chinese herbs have been found to inhibit proliferation, induce apoptosis, suppress angiogenesis, retard metastasis and enhance chemotherapy, exhibiting anti-cancer potential both in vitro and in vivo. This article summarizes recent advances in in vitro and invivo research on the anti-cancer effects and related mechanisms of some promising natural products. These natural products are also reviewed for their therapeutic potentials, including flavonoids (gambogic acid, curcumin, wogonin and silibinin), alkaloids (berberine), terpenes (artemisinin, β-elemene, oridonin, triptolide, and ursolic acid), quinones (shikonin and emodin) and saponins (ginsenoside Rg3), which are isolated from Chinese medicinal herbs. In particular, the discovery of the new use of artemisinin derivatives as excellent anti-cancer drugs is also reviewed.

Oridonin Induces Apoptosis, Inhibits Migration and Invasion on Highly-Metastatic Human Breast Cancer Cells

Oridonin, a natural tetracycline diterpenoid isolated from Chinese herb Rabdosia rubescens, has been reported to be a potent cytotoxic agent against a wide variety of tumors. However, its effect on highly metastatic breast cancer cells has not been addressed. In this study, we investigated the effects of oridonin on growth, migration and invasion of highly-metastatic human breast cancer cells. Our results showed that oridonin induced potent growth inhibition on human breast cancer cells MCF-7 and MDA-MB-231 in a time- and dose-dependent manner. According to the flow cytometric analysis, oridonin suppressed MCF-7 cell growth by cell cycle arrest at the G2/M phase and caused accumulation of MDA-MB-231 cells in the Sub-G1 phase. The induced apoptotic effect of oridonin was further confirmed by a morphologic characteristics assay and TUNEL assay. Oridonin triggered the reduction of Bcl-2/Bax ratio, caspase-8, NF-κB (p65), IKKα, IKKβ, phospho-mTOR, and increased expression level of cleaved PARP, Fas and PPARγ in a time-dependent manner. Immunofluorescent analysis showed that γH2AX-containing nuclear foci were significant in oridonin-treated MDA-MB-231 cells. Meanwhile, oridonin significantly suppressed MDA-MB-231 cell migration and invasion, decreased MMP-2/MMP-9 activation and inhibited the expression of Integrin β1 and FAK. In conclusion, oridonin inhibited the growth and induced apoptosis in breast cancer cells, which might be related to DNA damage and activation of intrinsic or extrinsic apoptotic pathways. Moreover, oridonin also inhibited tumor invasion and metastasis in vitro possibly via decreasing the expression of MMPs and regulating the Integrin β1/FAK pathway in MDA-MB-231 cells.

Ganoderic acid DM, a natural triterpenoid, induces DNA damage, G1 cell cycle arrest and apoptosis in human breast cancer cells

Ganoderic acid DM (GADM) is a triterpenoid isolated from Ganoderma lucidum, a well-known edible medicinal mushroom. In the present study, we found that GADM effectively inhibited cell proliferation and colony formation in MCF-7 human breast cancer cells, which was much stronger than that of MDA-MB-231 breast cancer cells. GADM both concentration- and time-dependently mediated G1 cell cycle arrest and significantly decreased the protein level of CDK2, CDK6, cycle D1, p-Rb and c-Myc in MCF-7 cells. Moreover, GADM obviously induced DNA fragmentation and cleavage of PARP which are the characteristics of apoptosis and decreased the mitochondrial membrane potential in MCF-7 cells. Besides, we also showed that GADM elicited DNA damage as measured by comet assay which is a sensitive method for DNA damage detection. γ-H2AX, a marker of DNA damage, was also slightly up-regulated after treated with GADM for 6h, suggesting that the G1 cell cycle arrest and apoptosis induced by GADM may be partially resulted from GADM-induced DNA damage. These results have advanced our current understandings of the anti-cancer mechanisms of GADM.

Anti-cancer properties of triterpenoids isolated from Ganoderma lucidum -- a review

Introduction: Triterpenoids isolated from Ganoderma lucidum are a class of naturally occurring compounds and structurally highly oxidized lanostanes. Accumulated data show that triterpenoids exhibit a broad spectrum of anti-cancer properties, including anti-proliferative, anti-metastatic and anti-angiogenic activities. A systematic summary and knowledge of future prospects are necessary to facilitate further studies on this species. Areas covered: This review aims to summarize and analyze the current knowledge on the anti-cancer properties and mechanisms of G. lucidum triterpenoids (GLTs) and discuss the future prospects of the application of GLTs in cancer treatment. Expert opinion: Extensive research over the last 10 years has provided evidence of the anti-cancer activities of GLTs in different stages of carcinogenesis. These activities include cell cycle arrest, induction of apoptosis and autophagy, and suppression of metastasis and angiogenesis. However, the exact molecular mechanisms involved in these processes remain unclear. Androgen receptor, nuclear factor-kappa B, activator protein-1, p53 and 14-3-3 are reportedly involved in the anti-cancer properties of GLTs. Animal models further shed light on the development of GLTs as anti-cancer agents. However, more research and clinical trials are necessary to exploit these compounds.

Platycodin D induces apoptosis, and inhibits adhesion, migration and invasion in HepG2 hepatocellular carcinoma cells.

BACKGROUND Platycodin D (PD), a triterpenoid saponin isolated from the Chinese medicinal herb Platycodonis radix, possesses anti-cancer effects in several cancer cell lines. The aim of this study was to evaluate its anti- cancer activities in hepatocellular carcinoma cells. MATERIALS AND METHODS MTT and colony formation assays were performed to evaluate cell proliferation, along with flow cytometry and Western blotting for apoptosis. Cell adhesion was tested by observing cellular morphology under a microscope, while the transwell assay was employed to investigate the cell migration and invasion. RESULTS PD concentration-dependently inhibited cell proliferation in both HepG2 and Hep3B cells, and significantly suppressed colony formation and induced apoptosis in HepG2 cells. The protein levels of cleaved poly ADP-ribose polymerase (PARP) and Bax were up-regulated while that of survivin was down-regulated after treatment with PD. Moreover, PD not only obviously suppressed the adhesion of HepG2 cells to Matrigel, but also remarkably depressed their migration and invasion induced by 12-O-tetradecanoylphorbol 13-acetate (TPA). CONCLUSIONS PD presents anti-cancer potential in hepatocellular carcinoma cells via inducing apoptosis, and inhibiting cell adhesion, migration and invasion, indicating promising features as a lead compound for anti-cancer agent development.

Cucurbitacin B induced ATM-mediated DNA damage causes G2/M cell cycle arrest in a ROS-dependent manner.

Cucurbitacins are a class of triterpenoids widely distributed in plant kingdom with potent anti-cancer activities both in vitro and in vivo by inducing cycle arrest, autophagy, and apoptosis. Cucurbitacin B (Cuc B), could induce S or G2/M cell cycle arrest in cancer cells while the detailed mechanisms remain to be clear. This study was designed to precisely dissect the signaling pathway(s) responsible for Cuc B induced cell cycle arrest in human lung adenocarcinoma epithelial A549 cells. We demonstrated that low concentrations of Cuc B dramatically induced G2/M phase arrest in A549 cells. Cuc B treatment caused DNA double-strand breaks (DSBs) without affecting the signal transducer and activator of transcription 3 (STAT3), the potential molecular target for Cuc B. Cuc B triggers ATM-activated Chk1-Cdc25C-Cdk1, which could be reversed by both ATM siRNA and Chk1 siRNA. Cuc B also triggers ATM-activated p53-14-3-3-σ pathways, which could be reversed by ATM siRNA. Cuc B treatment also led to increased intracellular reactive oxygen species (ROS) formation, which was inhibited by N-acetyl-l-cysteine (NAC) pretreatment. Furthermore, NAC pretreatment inhibited Cuc B induced DNA damage and G2/M phase arrest. Taken together, these results suggested that Cuc B induces DNA damage in A549 cells mediated by increasing intracellular ROS formation, which lead to G2/M cell phase arrest through ATM-activated Chk1-Cdc25C-Cdk1 and p53-14-3-3-σ parallel branches. These observations provide novel mechanisms and potential targets for better understanding of the anti-cancer mechanisms of cucurbitacins.

Synergistic anti-cancer activity of the combination of dihydroartemisinin and doxorubicin in breast cancer cells.

BACKGROUND Dihydroartemisinin (DHA) exhibits potent anti-malarial and anti-cancer activities. This study aimed to investigate the anti-proliferative effects of a combination of DHA and doxorubicin (DOX) on human breast cancer cells. METHODS MTT assay and the combination index (CI) were used to show the anti-proliferative effects and calculate the synergism potential, respectively. Flow cytometry assay was used to detect apoptosis and the intracellular accumulation of DOX. JC-1 staining was used to determine the mitochondrial membrane potential. Western blot analysis was used to detect the protein expression of some apoptosis-related molecules. RESULTS Asynergistic anti-proliferative effect was found, and the enhanced anti-cancer activity was observed to be accompanied by the prompt onset of apoptosis in MCF-7 cells. The combinative treatment remarkably decreased the mitochondrial membrane potential and activated caspase cascades more than the mono-treatment. Pretreatment with DHA also did not influence the accumulation of DOX in MCF-7 cells. CONCLUSION This study presented a new opportunity to enhance the effectiveness of future treatment regimens of breast cancer using DOX.

Anti-angiogenic effect of furanodiene on HUVECs in vitro and on zebrafish in vivo.

ETHNOPHARMACOLOGICAL RELEVANCE Furanodiene is an active ingredient of the traditional Chinese medicine, Rhizoma Curcumae, commonly used for the treatment of cancer in China. AIM OF THE STUDY To investigate the anti-cancer property of Rhizoma Curcumae, this study describes the anti-angiogenic activities of furanodiene in human umbilical vein endothelial cells (HUVECs) in vitro and in zebrafish in vivo. MATERIALS AND METHODS HUVECs were treated with different doses of furanodiene in the presence or absence of vascular endothelial growth factor (VEGF). The anti-proliferative effect of furanodiene was measured using the XTT assay. The anti-migration and anti-invasion activities of this compound were investigated with a wound-healing migration model and a three-dimensional cell invasion model, respectively. The effects of furanodiene on HUVEC differentiation were assessed by in vitro tube formation in Matrigel™. The expression of related proteins was detected by Western blot. Morphological observations of zebrafish were evaluated in transgenic Tg (fli1: EGFP) zebrafish embryos. RESULTS Our results showed that furanodiene exposure could significantly inhibit the proliferation of HUVECs in a dose-dependent manner and inhibit VEGF-induced proliferation at a low dose. Relative to the VEGF-induced control, the number of invading and migrating cells was significantly reduced in the furanodiene-treated groups. Furanodiene also dramatically suppressed tube formation and p-Akt (Ser473), p-Erk 1/2 (Thr202/Tyr204), ICAM-1, p-p85 (Ser428) as well as p85 protein expression. Furthermore, exposure to furanodiene inhibited angiogenesis in the zebrafish model. CONCLUSIONS This study demonstrated that furanodiene exposure exhibits a potential anti-angiogenic effect through suppression of endothelial cell growth, invasion, migration and tube formation via regulation of the PI3K pathway. This potential anti-angiogenic effect of furanodiene may play an important role in the anti-tumor activity of the traditional Chinese medicine, Rhizoma Curcumae.

Ganoderiol A-enriched extract suppresses migration and adhesion of MDA-MB-231 cells by inhibiting FAK-SRC-paxillin cascade pathway.

Cell adhesion, migration and invasion are critical steps for carcinogenesis and cancer metastasis. Ganoderma lucidum, also called Lingzhi in China, is a traditional Chinese medicine, which exhibits anti-proliferation, anti-inflammation and anti-metastasis properties. Herein, GAEE, G. lucidum extract mainly contains ganoderiol A (GA), dihydrogenated GA and GA isomer, was shown to inhibit the abilities of adhesion and migration, while have a slight influence on that of invasion in highly metastatic breast cancer MDA-MB-231 cells at non-toxic doses. Further investigation revealed that GAEE decreased the active forms of focal adhesion kinase (FAK) and disrupted the interaction between FAK and SRC, which lead to deactivating of paxillin. Moreover, GAEE treatment downregulated the expressions of RhoA, Rac1, and Cdc42, and decreased the interaction between neural Wiskott-Aldrich Syndrome protein (N-WASP) and Cdc42, which impair cell migration and actin assembly. To our knowledge, this is the first report to show that G.lucidum triterpenoids could suppress cell migration and adhesion through FAK-SRC-paxillin signaling pathway. Our study also suggests that GAEE may be a potential agent for treatment of breast cancer.

Ganoderma lucidum extract induces G1 cell cycle arrest, and apoptosis in human breast cancer cells.

Ganoderma lucidum (Fr.) Karst is a traditional Chinese herb that has been widely used for centuries to treat various diseases including cancer. Herein, an ethanol-soluble and acidic component (ESAC), which mainly contains triterpenes, was prepared from G. lucidum and its anti-tumor effects in vitro were tested on human breast cancer cells. Our results showed that ESAC reduced the cell viability of MCF-7 and MDA-MB-231 cells in a concentration-dependent manner with IC(50) of about 100 μg/mL and 60 μg/mL, respectively. DNA damage was detected by Comet assay and the increased expression of γ-H2AX after ESAC treatment was determined in MCF-7 cells. Moreover, ESAC effectively mediated G1 cell cycle arrest in both concentration- and time-dependent manners and induced apoptosis as determined by Hoechst staining, DNA fragment assay and Western blot analysis in MCF-7 cells. In conclusion, ESAC exerts anti-proliferation effects by inducing DNA damage, G1 cell cycle arrest and apoptosis in human breast cancer cells.