Fu-Xiang Ran

Cytotoxic activity of some Asarum plants.

The cytotoxic activity against some tumor cell lines of 16 commonly used species of Asarum was evaluated in this study. All of these plants were widely used in Asian countries as traditional medicines or folk medicines. Their inhibitory activities against four tumor cell lines (HL-60, BGC-823, KB and Bel-7402) were compared. It was observed that 10 of the tested extracts (eight ethanol extracts and two water extracts) among 32 extracts of these plants showed cytotoxic activity. Those 95% ethanol extractions from A. caudigerellum, A. forbesii, A. inflatum and A. maximum exhibited the highest cytotoxic activity, and 95% ethanol extracts or water extracts of A. sieboldii var. seoulense, A. himalaicum, A. splendens and A. crispulatum showed selective activity against one or two cells among the tested tumor cells. This is the first report of Asarum plants possessing cytotoxic activity against tumor cell lines.

YSY01A, a Novel Proteasome Inhibitor, Induces Cell Cycle Arrest on G2 Phase in MCF-7 Cells via ERα and PI3K/Akt Pathways

Given that the proteasome is essential for multiple cellular processes by degrading diverse regulatory proteins, inhibition of the proteasome has emerged as an attractive target for anti-cancer therapy. YSY01A is a novel small molecule compound targeting the proteasome. The compound was found to suppress viability of MCF-7 cells and cause limited cell membrane damage as determined by sulforhodamine B assay (SRB) and CytoTox 96® non-radioactive cytotoxicity assay. High-content screening (HCS) further shows that YSY01A treatment induces cell cycle arrest on G2 phase within 24 hrs. Label-free quantitative proteomics (LFQP), which allows extensive comparison of cellular responses following YSY01A treatment, suggests that various regulatory proteins including cell cycle associated proteins and PI3K/Akt pathway may be affected. Furthermore, YSY01A increases p-CDC-2, p-FOXO3a, p53, p21Cip1 and p27Kip1 but decreases p-Akt, p-ERα as confirmed by Western blotting. Therefore, YSY01A represents a potential therapeutic for breast cancer MCF-7 by inducing G2 phase arrest via ERα and PI3K/Akt pathways.

Effects of CS-1 on A431 cell proliferation, cell cycle, and epidermal growth factor receptor signal transduction

CS-1, a new alkaloid with a molecular formula of C(21)H(20)O(8)N(2)S, is extracted from traditional Chinese medicine. Previous studies have shown that CS-1 can inhibit the proliferation of several human carcinoma cells in vivo and in vitro. The aims of this study are to investigate the anti-tumor effect and mechanism of CS-1 in epidermal growth factor receptor (EGFR) signaling pathway in human A431 cell line. Through the sulforhodamine B assay, we found that CS-1 inhibited A431 cell proliferation in the concentration- and time-dependent manners. The inhibitory rate ranged from 14.5% to 87.8% after 24 h of incubation. High content screening (HCS) multi-parameters cytotoxicity analysis showed that CS-1 at high concentration had slight cytotoxicity that resulted from the cell permeabilization and slight reduction in total mitochondrial mass, whereas no change in nucleus size/morphology and lysosomal mass-pH was found. The cytotoxicity of CS-1 was not a major reason for its anti-proliferative effect. Cell cycle analysis indicated that CS-1 induced G1-phase arrest in A431 cells in a time-dependent manner at high concentration (2.5 μM), and S-phase arrest at low concentration (0.625 μM). The HCS assay also showed that CS-1 could inhibit the EGFR internalization, extracellular-signal-regulated kinase (Erk)/mitogen-activated protein kinase translocation to nucleus, the accumulation of phosphorylated protein kinase B (Akt), signal transducer and activator of transcription 3 (STAT3), and cyclin D1 in the nucleus. These results were confirmed by the western blot analysis. CS-1 might inhibit the epidermal growth factor binding to its receptor, resulting in the inhibition of the accumulation of phosphorylated Erk and Akt, and STAT3 in the nucleus, and affecting the transcription of cyclin D1 and cell cycle arrest in G1/S phase.

Angiogenesis inhibition and cell cycle arrest induced by treatment with Pseudolarix acid B alone or combined with 5-fluorouracil

Angiogenesis inhibitors combined with chemotherapeutic drugs have significant efficacy in the treatment of a variety of cancers. Pseudolarix acid B (PAB) is a traditional pregnancy-terminating agent, which has previously been shown to reduce tumor growth and angiogenesis. In this study, we used the high content screening assay to examine the effects of PAB on human umbilical vein endothelial cells (HUVECs). Two hepatocarcinoma 22-transplanted mouse models were used to determine PAB efficacy in combination with 5-fluorouracil (5-Fu). Our results suggested that PAB (0.156-1.250 μM) inhibited HUVECs motility in a concentration-dependent manner without obvious cytotoxicity in vitro. In vivo, PAB (25 mg/kg/day) promoted the anti-tumor efficacy of 5-Fu (5 mg/kg/2 days) in combination therapy, resulting in significantly higher tumor inhibition rates, lower microvessel density values, and prolonged survival times. It was also demonstrated that PAB acted by blocking the cell cycle at both the G(1)/S boundary and M phase, down-regulation of vascular endothelial growth factor, hypoxia-inducible factor 1α and cyclin E expression, and up-regulation of cdc2 expression. These observations provide the first evidence that PAB in combination with 5-Fu may be useful in cancer treatment.

Proteasome Inhibitor YSY01A Abrogates Constitutive STAT3 Signaling via Down-regulation of Gp130 and JAK2 in Human A549 Lung Cancer Cells

Proteasome inhibition interfering with many cell signaling pathways has been extensively explored as a therapeutic strategy for cancers. Proteasome inhibitor YSY01A is a novel agent that has shown remarkable anti-tumor effects; however, its mechanisms of action are not fully understood. Here we report that YSY01A is capable of suppressing cancer cell survival by induction of apoptosis. Paradoxically, we find that YSY01A abrogates constitutive activation of STAT3 via proteasome-independent degradation of gp130 and JAK2, but not transcriptional regulation, in human A549 non-small cell lung cancer cells. The reduction in gp130 and JAK2 can be restored by co-treatment with 3-methyladenine, an early-stage autophagy lysosome and type I/III PI3K inhibitor. YSY01A also effectively inhibits cancer cell migration and lung xenograft tumor growth with little adverse effect on animals. Thus, our findings suggest that YSY01A represents a promising candidate for further development of novel anticancer therapeutics targeting the proteasome.

Anticancer Effect of a Novel Proteasome Inhibitor,YSY01A,via G2/M Arrest in PC-3M Cells in vitro and in vivo

YSY01A is a new tripeptideboronic acid and an analog of PS341. However, YSY01As antitumor effects and mechanism have not yet been elucidated. This study demonstrates that YSY01A inhibited proteasome activity by combining with the chymotrypsin-like (CT-L) site (β5i/β5), the post-glutamyl peptide hydrolase (PGPH) site (β1i/β1) and the trypsin-like (T-L) site (β2i/β2) in special fluorgonic substrates and proteasome probe tests. We explored the anticancer effect using methyl thiazolyltetrazolium (MTT) or sulforhodamine B (SRB), and PC-3M cells were sensitive to YSY01A among the four cancer cell types tested. The YSY01A antiproliferative effect was stronger than that of PS341. In vivo, YSY01A (1.25, 2.25, and 3.25 mg/kg) inhibited PC-3M cell xenograft tumor growth, and the tumor volume inhibition rate was approximately 40% to 60%. YSY01A arrested PC-3M cells in the G2/M phase of the cell cycle by flow cytometry (FCM). Many proteins related to the cell cycle were analyzed using western blot, and YSY01A was shown to increase p21, p27, cyclinB1, P-cdc2 (tyr15) and wee1 protein expression in both cells and tumor tissue in a concentration-dependent manner. YSY01A, a proteasome inhibitor, exerts anticancer effects on PC-3M cells in vitro and in vivo. The mechanism of the YSY01A-mediated antitumor effect is that the cell cycle is arrested at the G2/M stage. This study suggests that YSY01A may be a novel therapeutic agent for prostate cancer.

Inhibition Effect and Mechanism of YSY-01A,a Novel Proteasome Inhibitor,on Tumor-induced Angiogenesis

Compound YSY-01A is a recently synthesized proteasome inhibitor.It has been proved for potent growth-inhibitory effect on tumor cells in previous studies.However,the effect of YSY-01A on tumor angiogenesis remains unclear.Our research aims to reveal the inhibition effect and mechanism of YSY-01A on tumor-induced angiogenesis.Firstly,we combined the Sulforhodamine B(SRB) assay and Transwell co-culture model to observe the inhibition of YSY-01A on human umbilical vein endothelial cells(HUVECs) proliferation induced by tumor cells(HT-29 cells).In succession,high content screening(HCS) assay was used to investigate effect of YSY-01A on NF-κB nuclear translocation in HT-29 cells.Finally,Western blot was used to measure the expression of hypoxia-inducible factor-1α(HIF-1α) and vascular endothelial growth factor(VEGF) in HT-29 cells inhibited by YSY-01A.To further determine mechanism of inhibition,SRB and HCS methods were used to investigate the effect of YSY-01A against HUVECs proliferation and motility,respectively.The results showed that YSY-01A could prohibit HUVECs proliferation induced by HT-29 cells in a concentration-dependent manner.Furthermore,YSY-01A significantly inhibited NF-κB nuclear translocation and reduced the expression of HIF-1α and VEGF in HT-29 cells.Further investigation revealed concentration-dependent suppress of YSY-01A on HUVECs proliferation and motility without obvious cytotoxic effect.In conclusion,through proteasome inhibition,YSY-01A could down-regulate pro-angiogenesis factors expression in tumor cells and exhibit remarkable anti-angiogenesis activity on vascular endothelial cells.