c-Met: A potential therapeutic target for hepatocellular carcinoma

The approval of receptor tyrosine kinase (RTK) targeted agent sorafenib as the first effective drug for the systemic treatment of advanced hepatocellular carcinoma (HCC) represents a milestone in the treatment of this disease. A better understanding of HCC pathogenesis will lead to development of novel targeted treatments. As a typical member of the RTK family, c-Met represents an intriguing target for cancer therapy. The c-Met signaling pathway has been shown to be deregulated and to correlate with poor prognosis in a number of major human cancers. This review discusses the possibility of c-Met as a target in HCC treatment from the following respects: i) c-Met expression and activation profile in HCC, ii) relationship between c-Met and clinicopathologic state and prognosis of HCC, iii) role of c-Met signaling activity in HCC genesis and progression, and iv) strategy of c-Met pathway targeting therapy in HCC treatment.

Prospects for using pre-exposure prophylaxis to control the prevalence of HIV/AIDS in China

Although important progress has been achieved in combating HIV/AIDs over the past 30 years, HIV/AIDs is still a serious threat to today's world. In China, figures on the incidence of this disease have painted a less than optimistic outlook. As the prevailing methods of preventing HIV/AIDS are all partially effective, novel and effective preventive interventions are needed in order to control the spread of the disease. Pre-exposure prophylaxis (PrEP) is one of the most promising prevention strategies and has garnered great attention worldwide. Current clinical trials on the efficacy and safety of this strategy have had some favorable results though major challenges around the world remain. Thus, China has taken an active part in the PrEP study to limit the prevalence of HIV/AIDS. This article describes the status of the PrEP study and discusses the opportunities and challenges encountered when implementing this strategy in China.

Evidence-based research on traditional Japanese medicine, Kampo, in treatment of gastrointestinal cancer in Japan

Gastrointestinal cancer is a great threat to human health in Japan. Conventional anticancer therapies including surgery, radiation, and chemotherapy are the main strategies and play important roles in curing this disease or extending the life of patients with these cancers. On the other hand, patients undergo great suffering induced by these treatments. Kampo, the Japanese traditional medicine, has been used in clinics to reduce side effects and to improve the quality of life of gastrointestinal cancer patients in Japan. In order to testify to the efficacy and safety of these Kampo medicines and to clarify the underlying mechanisms, a number of clinical and basic studies were implemented in the past several decades. These studies suggested the benefits of Kampo medicine as an adjuvant to conventional anti-cancer therapies in treating gastrointestinal cancer. Since the safety and efficacy as well as quality control of traditional medicine have long been focused worldwide, the development course of Kampo medicine may provide reference to other countries in the world.

[Expression of c-Cbl, Cbl-b, and epidermal growth factor receptor in gastric carcinoma and their clinical significance]

BACKGROUND AND OBJECTIVE

c-Cbl and Cbl-b are two ubiquitous members of the Casitas B-lineage lymphoma (Cbl) family, which play important roles in the downregulation of epidermal growth factor receptor (EGFR) by acting as E3 ubiquitin ligases and multiadaptor proteins. This study investigated the expression of c-Cbl, Cbl-b, and EGFR in gastric carcinoma and its clinical significance.

METHODS

The expressions of c-Cbl, Cbl-b, and EGFR were detected by immunohistochemistry using tissue microarrays consisting of 124 specimens of gastric carcinoma and 16 specimens of normal gastric mucosa. The relationship between the expressions of c-Cbl, Cbl-b, and EGFR and clinicopathologic factors of gastric carcinoma were analyzed statistically.

RESULTS

The positive rates of c-Cbl, Cbl-b, and EGFR were higher in the gastric carcinoma group than in the normal group (71.0% vs. 18.0%, P<0.01; 82.3% vs. 25.0%, P<0.01; 56.5% vs. 12.5%, P<0.01, respectively). The expression of c-Cbl was positively correlated with depth of invasion (r=0.219, P=0.015), and TNM staging (r=0.266, P=0.003). The expression of Cbl-b was positively correlated with lymph node metastasis (r=0.190, P<0.034) and TNM staging (r=0.298, P<0.001). The expression of EGFR was positively correlated with depth of invasion (r=0.286, P<0.001) and TNM staging (r=0.362, P=0.000). The expression of both c-Cbl and Cbl-b was positively correlated with EGFR (r=0.241, P=0.007; r=0.183, P=0.042, respectively). Synchronous strong-positive expressions of c-Cbl, Cbl-b, and EGFR were observed in 27 specimens of gastric carcinoma, most of which were at advanced stage.

CONCLUSIONS

Overexpressions of c-Cbl, Cbl-b, and EGFR are closely related to the invasion and progression of gastric carcinoma. c-Cbl and Cbl-b may serve as novel molecular markers for gastric carcinoma.

β-Elemene induces apoptosis as well as protective autophagy in human non-small-cell lung cancer A549 cells

OBJECTIVES

β-Elemene, a novel traditional Chinese medicine, has been shown to be effective against a wide range of tumours. In this study, the antitumour effect of β-elemene on human non-small-cell lung cancer (NSCLC) A549 cells and the mechanism involved have been investigated.

METHODS

Cell viability and apoptosis were measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry, respectively. Protein expression was assayed by Western blotting. Autophagy was evaluated under fluorescence microscopy and transmission electron microscopy.

KEY FINDINGS

β-Elemene inhibited the viability of A549 cells in a dose-dependent manner. This suppression of cell viability was due to the induction of apoptosis. Further study showed that β-elemene inhibited the activity of the PI3K/Akt/mTOR/p70S6K1 signalling pathway, and at the same time it triggered a robust autophagy. The autophagy was characterized by the accumulation of punctate LC3 dots in the cytoplasm, morphological changes, and the increased levels of LC3-II as well as Atg5-Atg12 conjugated proteins. Inhibition of autophagy with chlorochine significantly enhanced the antitumour effect of β-elemene.

CONCLUSIONS

Our data indicated that β-elemene inhibited the activity of the PI3K/Akt/mTOR/p70S6K1 signalling pathway in human NSCLC A549 cells, which resulted in apoptosis as well as protective autophagy. A combination of β-elemene with autophagy inhibitor might be an effective therapeutic option for advanced NSCLC.

Ubiquitin ligase c-Cbl is involved in tamoxifen-induced apoptosis of MCF-7 cells by downregulating the survival signals

BACKGROUND

Tamoxifen (TAM) is a nonsteroidal antiestrogen that has been widely used in the treatment of breast cancer through its anti-estrogen activity. Recent studies show that TAM is cytotoxic to both estrogen receptor (ER)-positive and ER-negative cells via the induction of apoptosis. However, the molecular mechanisms of this effect are not well understood. In the present study, we investigated the roles of c-Src, ERK, AKT and c-Cbl ubiquitin ligases during TAM-induced apoptosis of MCF-7 cells.

MATERIAL AND METHODS

MCF-7 cell proliferation and apoptosis were measured by 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, and flow cytometry, respectively. c-Cbl expression, and the activity of c-Src, ERK, AKT were assayed by Western blotting. Overexpression of the wild and the dominant-negative type of c-Cbl (70Z/Cbl) were achieved by transient transfection of plasmids encoding c-Cbl and 70Z/Cbl, respectively, and were confirmed by Western blotting. Statistical analysis was performed using the t-test, and a p-value <0.05 was considered to be statistically significant.

RESULTS

A high concentration of TAM (25 μM) induced a time-dependent apoptosis of MCF-7 cells. ERK1/2 and AKT were activated during TAM-induced apoptosis. The ERK1/2 inhibitor PD98059, the PI3K/Akt inhibitor LY294002, and the c-Src inhibitor PP2 all enhanced TAM action. Moreover, the ubiquitin ligase c-Cbl was up-regulated during this process. Over-expression of c-Cbl significantly enhanced the apoptosis-inducing effects of TAM, while 70Z/Cbl suppressed the apoptosis-inducing effects of TAM. Further investigation revealed that, overexpression of c-Cbl significantly downregulated the c-Src protein levels and TAM-induced AKT activity. But 70Z/Cbl significantly upregulated TAM-induced ERK and AKT activity.

CONCLUSIONS

This study demonstrates that c-Src, ERK, and AKT played a protective role during TAM-induced apoptosis, and that c-Cbl sensitized MCF-7 cells to TAM by modulating the expression of c-Src, and TAM-induced ERK and AKT activity.

In vitro antitumor effect of the proteasome inhibitor bortezomib on human gastric cancer SGC7901 cells

AIM: To investigate the anti-tumor effect of bortezomib, a proteasome inhibitor, on human gastric cancer SGC7901 cells and to explore possible mechanism involved.

METHODS: Human gastric cancer SGC7901 cells were cultured and treated with different concentrations of bortezomib (1-500 nmol/L) for 24-48 h. Cell viability was determined by MTT assay. Apoptosis was detected by flow cytometry. The cleavage of PARP and caspase-3 and level of phosphor-Akt were determined by Western blot.

RESULTS: Bortezomib inhibited the viability of SGC7901 cells in a dose- and time-dependent manner. The IC₅₀ value at 48 h was 67.39 nmol/L. Treatment with 60 or 180 nmol/L of bortezomib induced cell cycle arrest at G₂/M phase at both 24 and 48 h but induced apoptosis only at 48 h. The cleavage of caspase-3 and PARP was observed in cells treated with 60 or 180 nmol/L of bortezomib for 48 h. Treatment with bortezomib for 48 h down-regulated the level of phosphor-Akt in SGC7901 cells.

CONCLUSION: Bortezomib induced apoptosis and cell cycle arrest at G₂/M phase by inhibiting the activity of the PI3K/Akt signaling pathway in human gastric cancer SGC7901 cells.

Treatment with β-elemene inhibits ERK activation and down-regulates GST-π expression in human gastric cancer cell line SGC7901/Adr

AIM: To investigate the effect of treatment with β-elemene on the activation of extracellular signal-regulated kinase (ERK) and expression of glutathione transferase-π (GST-π) in human gastric cancer cell line SGC7901/Adr.

METHODS: After SGC7901/Adr cells were treated with different concentrations of β-elemene for different durations, cell proliferation was measured by MTT assay, and protein expression was detected by Western blot. All experimental data were analyzed with the SPSS 13.0 software package.

RESULTS: β-elemene inhibited the proliferation of SGC7901/Adr cells in a time-dependent manner. The half maximal inhibitory concentrations of β-elemene at 24, 48, and 72 h in SGC7901/Adr cells were 53.48, 28.78 and 14.78 mg/L, respectively. In untreated control cells, ERK was basically phosphorylated. Treatment with β-elemene (50 mg/L) for 24 h significantly decreased the expression of phosphorylated ERK and GST-π in SGC7901/Adr cells.

CONCLUSION: β-elemene could inhibit the activation of the ERK signaling pathway and thereby down-regulate the expression of GST-π in SGC7901/Adr cells.

Role of PI3K/Akt and MAPK/ERK pathways in gastric cancer exosome-mediated promotion of tumor cell proliferation

AIM: To investigate the effect of gastric cancer exosomes on homologous tumor cell proliferation and to evaluate the role of PI3K/Akt and MAPK/ERK pathways in this process.

METHODS: Exosomes were isolated and purified from human gastric cancer MGC803 cells by serial centrifugation and sucrose gradient ultracentrifugation and observed by electron microscopy. Cell proliferation was measured by MTT assay, and protein expression was assayed by Western blot.

RESULTS: Gastric cancer exosomes had a characteristic saucer-like shape that was limited by a lipid bilayer, and their diameter ranged from 30 to 100 nm. CD9 and TSG101 were abundantly distributed on the surface of exosomes. Gastric cancer exosomes significantly increased MGC803 and SGC7901 cell proliferation in a time- and dose-dependent manner. Treatment with exosomes up-regulated the expression of phosphorylated Akt and ERK in a time-dependent manner.

CONCLUSION: Gastric cancer exosomes promote homologous tumor cell proliferation possibly by activating the PI3K/Akt and MAPK/ERK pathways.

Protective autophagy inhibits 5-FU-induced apoptosis in human gastric cancer cell line MGC803

AIM: To investigate whether 5-fluorouracil (5-FU) induces autophagy in human gastric cancer cell line MGC803 and to identify the role of autophagy in 5-FU -induced cell apoptosis.

METHODS: After cultured MGC803 cells were treated with 5-FU, cell proliferation was measured using MTT assay; cell apoptosis was determined by flow cytometry; protein expression was detected by Western blot; and autophagy was observed by fluorescent microscopy.

RESULTS: The concentration of 5-FU inducing a 50% inhibition of cell proliferation (IC₅₀) was 2.07 mg/L ± 1.14 mg/L in MGC803 cells. After treatment with 2 and 5 mg/L 5-FU for 48 h, the rates of cell apoptosis were 22.46% ± 3.21% and 32.27% ± 4.52%, respectively. Autophagy, characterized by an increase in the number of punctate LC3 dots and the level of LC3-II protein, was observed in cells treated with 5-FU. The activity of the PI3K/Akt/mTOR pathway was inhibited by 5-FU treatment. Inhibition of autophagy with chlorochine significantly enhanced 5-FU -induced apoptosis (P < 0.05).

CONCLUSION: 5-FU-induced protective autophagy prevents MGC803 cells from apoptosis. Combination therapy with 5-FU and autophagy inhibitors may be a promising therapeutic strategy for gastric cancer.

Role of tyrosine kinase Src in gastric cancer exosome-mediated promotion of tumor cell proliferation

AIM: To investigate the effect of gastric cancer exosomes on tumor cell proliferation and to evaluate the role of tyrosine kinase Src in this process.

METHODS: Exosomes were isolated and purified from gastric cancer SGC7901 cells by serial centrifugation and sucrose gradient ultracentrifugation and observed by electron microscopy. Cell proliferation was measured by MTT assay. Protein expression was assayed by Western blot.

RESULTS: Gastric cancer exosomes had a characteristic saucer-like shape that was limited by a lipid bilayer, and their diameter ranged from 30 to 100 nm. CD9 and TSG101 were abundant on the surface of exosomes. Gastric cancer exosomes significantly increased SGC7901 cell proliferation in a time- and dose-dependent manner. Compared with control cells, the proliferation of cells treated with 200 and 400 mg/L exosomes for 72 h were increased to 138% and 144%, respectively (both P < 0.01). The expression of phosphorylated Src in SGC7901 cells was up-regulated in a time- and dose-dependent manner after treatment with exosomes.

CONCLUSION: Gastric cancer exosomes promote tumor cell proliferation possibly by activating tyrosine kinase Src.

Bortezomib synergizes TRAIL-induced apoptosis in gastric cancer cells

Background/Aims Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) as a newly identified biological agent has shown promising antitumor effects in a wide range of cancers. However, gastric cancer cells are less sensitive than other cancer cells to TRAIL-induced apoptosis.Here, we combined TRAIL with bortezomib, a proteasomal inhibitor to induce apoptosis in three gastric cancer cell lines.Methods After the cells were treated with TRAIL and/or bortezomib, the cell viability, apoptosis and cell cycle distribution were examined. The levels of death receptors and the mitochondrial membrane potential were also detected. The expression of apoptosis-associated proteins was determined by Western blot.Results Bortezomib at low concentration significantly(P<0.05) enhanced the cytotoxic effect of TRAIL by enhancing apoptosis as well as cell cycle arrest at G2/M phase. The enhancement of efficiency of TRAIL by bortezomib involved up-regulation of death receptor 4 and 5, as well as reduction of the mitochondrial membrane potential. Further study showed that combined treatment with TRAIL and bortezomib down-regulated anti-apoptotic protein cIAP-1, and over expression of cIAP-1 significantly(P\0.05) reduced the synergistic effect between TRAIL and bortezomib.Conclusions Bortezomib synergizes TRAIL-induced apoptosis in human gastric cancer cells. The synergistic effect between these two drugs is associated with up-regulation of death receptors and down-regulation of cIAP-1.The combination of TRAIL and bortezomib might be an effective regimen for the treatment of advanced gastric cancer.

Oxaliplatin enhances TRAIL-induced apoptosis of gastric cancer BGC823 cells

AIM: To determine whether there is a synergistic effect between oxaliplatin and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in inducing the apoptosis of gastric cancer BGC823 cells.

METHODS: After BGC823 cells were cultured and treated with TRAIL and/or oxaliplatin, cell proliferation was measured using MTT assay; cell apoptosis was determined by flow cytometry after propidium iodide staining; and the distribution of lipid rafts and death receptors 4 (DR4) on cell membrane was analyzed by immunofluorescence staining with anti-cholera toxin B subunit, anti-DR4 antibody and rhodamine-conjugated fluorescent secondary antibody.

RESULTS: After BGC823 cells were treated with 1-1 000 µg/L TRAIL for 24 h, the reduced rates of cell proliferation did not exceed 20%. Treatment with 100 µg/L TRAIL for 24 h induced about 10% inhibition of cell proliferation and 4.12% ± 1.26% cell apoptosis. After BGC823 cells were treated with 1-50 mg/L oxaliplatin for 24 h, it was found that the half maximal inhibitory concentration (IC₅₀) was 37.36 mg/L ± 8.12 mg/L. Treatment with oxaliplatin (38 mg/L, IC₅₀ dose) plus TRAIL resulted in a dramatic increase in cell apoptosis when compared to treatment with TRAIL alone (19.83% ± 4.21% vs 40.42% ± 5.78%, P < 0.05). TRAIL at a concentration of 100 µg/L did not induce obvious lipid raft aggregation or DR4 clustering. Oxaliplatin (38 mg/L) significantly promoted lipid raft aggregation and DR4 clustering and induced the co-localization of DR4 and lipid rafts. Treatment with oxaliplatin and TRAIL for 24 h also induced DR4 clustering into aggregated lipid rafts.

CONCLUSION: Oxaliplatin enhances TRAIL-induced BGC823 cell apoptosis by clustering DR4 into lipid rafts.

Role of MAPK/ERK signaling pathway in gastric cancer exosome-induced apoptosis of Jurkat T cells

AIM: To investigate the role of the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated protein kinase (ERK) signaling pathway in gastric cancer exosome-induced apoptosis of Jurkat T cells.

METHODS: Gastric cancer exosomes were isolated and purified by serial centrifugation and sucrose gradient ultracentrifugation. The morphology of gastric cancer exosomes was observed by electron microscopy. Cell apoptosis was determined by propidium iodide staining and flow cytometry. The expression of caspase-3 and -8 and p-ERK was assayed by Western blot.

RESULTS: Gastric cancer exosomes, ranging in diameter from 30 to 100 nm, had a characteristic saucer-like shape that was limited by a lipid bilayer. These exosomes induced Jurkat T cell apoptosis in a time- and dose-dependent manner. Activation of caspase-3 and -8 and down-regulation of p-ERK expression were noted in exosome-induced apoptosis of Jurkat T cells.

CONCLUSION: Gastric cancer exosomes induce apoptosis of Jurkat T cells possibly by inhibiting the MAPK/ERK pathway.

Bortezomib enhances the sensitivity of gastric cancer cells to TRAIL-induced apoptosis by inhibiting the PI3K/Akt pathway

AIM: To investigate the effect of bortezomib on TRAIL-induced apoptosis in human gastric cancer cells, and to elucidate the role of the phosphoinositide 3-kinases (PI3K)/Akt signaling pathway in TRAIL-induced apoptosis of gastric cancer cells.

METHODS: Human gastric cancer MGC803 cells were cultured and treated with TRAIL and/or bortezomib. Cell viability was determined by MTT assay. Apoptosis was detected by flow cytometry. Caspase cleavage and the level of phosphor-Akt were determined by Western blot.

RESULTS: Cells were treated with either 20 or 50 nmol/L bortezomib, or 100 μg/L TRAIL for 24 h, or pretreated with bortezomib for 2 h followed by exposure to TRAIL for an additional 24 h. Compared with cells treated with TRAIL alone, cell viability was obviously lower and apoptosis rate was obviously higher in cells co-treated with TRAIL and 50 nmol/L bortezomib (cell viability: 35.1% ± 2.7% vs 71.0% ± 4.3%, P < 0.01; apoptosis rate: 31.3% ± 2.0% vs 8.2% ± 0.8%, P < 0.01). Pretreatment with 20 nmol/L bortezomib did not enhance the sensitivity of cells to TRAIL-induced apoptosis. TRAIL engagement led to PI3K/Akt activation. Bortezomib blocked the activation of PI3K/Akt signaling and enhanced the sensitivity of cells to TRAIL-induced apoptosis.

CONCLUSION: Bortezomib enhances TRAIL-induced apoptosis by blocking the activation of PI3K/Akt signaling pathway in human gastric cancer MGC803 cells.

The role of cbl family of ubiquitin ligases in gastric cancer exosome-induced apoptosis of Jurkat T cells

BACKGROUND. Exosomes are nanometer-sized vesicles with immunomodulatory functions, which are released by a diverse range of living cells. Although recent studies have shown that tumor-derived exosomes can suppress the function of T cells, the molecular mechanisms are not well understood. In the present study, we investigated the role of the Casitas B lineage lymphoma (cbl) family of ubiquitin ligases in gastric cancer exosome-induced apoptosis of Jurkat T cells. MATERIALS AND METHODS. By serial centrifugation and sucrose gradient ultracentrifugation, we isolated and purified the exosomes from gastric cancer SGC7901 cells, and identified them by electron microscopy and Western blotting. Cell apoptosis was detected using propidium iodide staining. Western blotting and RT-PCR was exploited to evaluate the expression of proteins and mRNA, respectively. RESULTS. Gastric cancer exosomes induced Jurkat T cell apoptosis in a time- and dose-dependent manner and activated caspases 3, 8 and 9. The expression of Cbl-b and c-Cbl was up-regulated during exosome-induced apoptosis of cells. Meanwhile, exosomes induced ubiquitination of the p85 subunit of phosphoinositide 3-kinase (PI3K) and reduced downstream Akt activity. Inhibition of proteasome led to partial restoration of Akt activity and cell apoptosis. DISCUSSION AND CONCLUSIONS. The Cbl family of ubiquitin ligases might be involved in regulation of exosome-induced apoptosis of Jurkat T cells by increasing PI3K proteasome degradation, inactivation of PI3K/Akt signaling, thus mediating some effects of caspase activation.

[Effects of Bufalin on SYK and CBL family proteins in induction of HL-60 cell apoptosis]

The study was aimed to explore the mechanism of SYK and CBL family of ubiquitin ligases in Bufalin-induced HL-60 cells apoptosis. Cell viability was tested by trypan blue staining and apoptosis was detected by using flow cytometry. The expressions of CBL and CBL-b and the phosphorylation of SYK were detected by using immunoprecipitation and Western blot. The results showed that Bufalin inhibited HL-60 cell proliferation in time- and dose-dependent manners. IC(50) of suppressing cell viability at 24, 48 and 72 hours were about 26.3, 7.8 and 2.0 nmol/L respectively. The high dose of bufalin already induced apoptosis of HL-60 cells at 8 hours. SYK was quickly phosphorylated, and the expressions of CBL and CBL-b were down-regulated after treatment with Bufalin. It is concluded that SYK activation and CBL protein down-regulation may be involved in Bufalin-induced HL-60 cell apoptosis.

Reversal effect of PI3-K inhibitor LY294002 on P-glycoprotein-mediated multidrug resistance of human leukemia cell line K562/DNR and gastric cancer cell line SGC7901/ADR

BACKGROUND AND OBJECTIVE

Phosphatidylinositol-3-kinase/protein kinase B (PI3-K/Akt) signaling pathway plays an important role in cell survival. This study was to explore the reversal effect of PI3-K inhibitor LY294002 on p-glycoprotein (P-gp)-mediated multidrug resistance in human leukemia cell line K562/DNR and gastric cancer cell line SGC7901/ADR.

METHODS

The cells were divided into simple drug-treated groups and LY294002 pretreated groups: the former groups received treatment of daunorubicin (DNR), adriamycin (ADR), vincristine (VCR) and etoposide (VP-16), respectively; the latter groups received pretreatment of LY294002 before drug treatment. Trypan blue dye exclusion method and MTT assay were used to detect the drug sensitivity of K562/DNR and SGC7901/ADR cells, and the effect of LY294002 on the drug resistance. The expression of P-gp and phosphorylated Akt (p-Akt) in K562/DNR, SGC7901/ADR and their parental cell lines K562 and SGC7901 was detected by Western blot. Intracellular drug accumulation was measured by flow cytometry (FCM).

RESULTS

LY294002 pretreatment significantly decreased the 50% inhibition concentration (IC(50)) of DNR, ADR, VCR and VP-16 for K562/DNR cells, with reverse efficiencies of 72.4%, 64.9%, 60.4% and 52.8%. In SGC7901/ADR cells, the similar result was obtained with a reverse efficiency of 31.0%. LY294002 pretreatment partially inhibited the expression of p-Akt and P-gp, and promoted the intracellular accumulation of DNR and ADR in K562/DNR and SGC7901/ADR cells, respectively.

CONCLUSION

LY294002 could partially reverse multidrug resistance in K562/DNR and SGC7901/ADR cells in vitro via inhibiting PI3-K/Akt pathway.

[The influence of bortezomib on HL-60 cell function induced by all-trans retinoic acid plus bufalin and its mechanism]

OBJECTIVE

To investigate changes in the adherent ability, the expression of adhesion related proteins Pyk2 and paxillin during HL-60 cells differentiation into granulocyte-monocyte induced by low-dose (LD) bufalin in combination with all-trans retinoic acid (ATRA), and to explore the effects of bortezomib on cellular adhesion and the expression of Pyk2 and paxillin.

METHODS

The expression of CD11b was detected by flow cytometry, cellular adherence ability by MTT assay, and the expressions of Pyk2, paxillin and tubulin by Western blot.

RESULTS

The combination of 5 nmol/L bufalin and 30 nmol/L ATRA induced HL-60 cells differentiation in a time-dependent manner, the percentages of CD11b positive cells treated for 2 d and 4 d being (20.0 +/- 2.8)% and (75.0 +/- 5.3)%, respectively, with the increasing of cellular adherence ability. Meanwhile the expressions of Pyk2 and Paxillin were also up-regulated in a time-dependent manner. Bortezomib suppressed HL-60 cell adhesion in a dose-dependent manner. At concentrations of 1 nmol/L and 10 nmol/L the adherence level were (7.8 +/- 0.1)% and (5.3 +/- 0.3)%, respectively, with down-regulation of Pyk2 but not Paxillin.

CONCLUSION

Pyk2 is involved in the regulation of cellular adherence function. Bortezomib might inhibit HL-60 cells adhension function by down-regulation of Pyk2 expression.

Dynamic of modernizing traditional Chinese medicine and the standards system for its development

This article reviewed the process of Traditional Chinese Medicine's modernization on a global scale. This process is motivated by the potential need for traditional medicine as a result of health transitions and increasing drug R&D based on know-how from TCM. The established standards system for modern medicine serves as a basic model yet has limitations in terms of comprehensively evaluating TCM. Spurred by policy committments, research to provide supplements suited to TCM's features and principles is underway. Advanced and interdisciplinary technology and methodology is expected to play an essential role in TCM development.

China-Japan enhance joint research cooperation for drug discoveries and development: News from CJMWDDT 2007 in Jinan, China

Viral hepatitis is currently a major global cause of morbidity and mortality. In some Asian countries like China and Japan, Hepatitis B and C in particular are the most common extremely infectious diseases and are likely to develop into liver cirrhosis. Furthermore, statistics indicate that patients with liver cirrhosis resulting from hepatitis B and C have an increased risk of developing hepatocellular carcinoma (HCC). Scientists have worked tirelessly to find curative therapeutic strategies to control chronic hepatitis and liver cirrhosis, accompanied by improvements in public health and living conditions. China's Shandong University and the University of Tokyo in Japan previously established a longterm cooperative relationship. Cooperative programs include co-training of postgraduates, exchanges of visiting scholars, academic symposia, and a bilateral international joint research program. Some substantive progress has been made as a result of bilateral endeavors. For instance, the Shandong University China-Japan Cooperation Center for Drug Discovery & Screening (SDU-DDSC) has enhanced to serve as an important platform for further close cooperation. At the same time, the International Advancement Center for Medicine & Health Research (IACMHR) - "Drug Discoveries and Therapeutics" and International Research and Cooperation Association for Bio & Socio-Sciences Advancement (IRCA-BSSA) - "BioScience Trends" were established (Visit http://www.ddtjournal.com and http://www.biosciencetrends.com ). The first China-Japan conference on new drug discoveries and therapeutics (CJMWDDT 2007) was recently held in Jinan, China May 27-29, 2007, which provided opportunities for further communication and cooperation and increased knowledge of new drug research and clinical cures for hepatitis. Financially supported by the National Natural Science Foundation of China (NSFC) and the Japan Society for the Promotion of Science (JSPS), the conference covered a wide range of topics in different areas of chemical biology, phytochemistry, medicinal chemistry, and pharmacology and it resulted in informed and genial discussions of hepatitis cures that yielded fruitful results. The active involvement and participation by attendees gave the conference a congenial atmosphere. In the end, an agreement was reached to work together on new drug discovery and effective hepatitis therapeutic strategies, and some agreements have resulted in the creation of handover protocols. The CJMWDDT 2007 was a highly successful scientific event that strengthened and promoted extensive cooperation between China and Japan for the development of new pharmaceutical products and hepatitis cures.

GMP implementation in China: A double-edged sword for the pharmaceutical industry

China's Good Manufacturing Practice (GMP) standards that mainly parallel WHO standards were made compulsory in 2004. However, GMP implementation had both positive as well as negative impacts on the pharmaceutical industry, with negatives including pharmaceutical companies suffering economic hardships, poor execution of GMP standards, and sequent health scares. This report briefly describes the problems with GMP implementation in China.

[Effect of bufalin-inducing apoptosis on Bcl-2 and PKC in HL-60 cells]

Previous study revealed that bufalin can inhibit proliferation, and induce apoptosis in some human cancer cell lines. However, the mechanism of its anticancer effect has not been fully understood. The present study was designed to investigate the effects of bufalin-induced apoptosis on Bcl-2 and PKC in human leukemic HL-60 cells. The cell viability was determined by trypan blue dye exclusion. The apoptosis was detected by morphology, flow cytometry and DNA agarose gel electrophoresis. The expressions of Bcl-2 and PKC were analyzed by Western blot, and activity of PKC was assayed by [gamma-(32)P] isotope incorporation method. The results showed as follows: (1) proliferation of HL-60 cells was inhibited by bufalin and the IC(50) at 24, 48, 72 hours were (25.8 +/- 2.1), (8.0 +/- 1.2) and (2.3 +/- 0.3) nmol/L, respectively. (2) apoptosis of HL-60 cells was induced when the cells were treated with bufalin at concentration of 50 nmol/L for 24 hours. (3) compared with control, treatment with bufalin at concentration of 50 nmol/L for 6 - 24 hours resulted in downregulation of protein expression, decrease of phosphorylation, and cleavage of Bcl-2, simultaneously. (4) the activity of total PKC was unchanged when HL-60 cells were exposed to 1 - 100 nmol/L bufalin for 30 minutes, but PKCbetaII underwent translocation from cytosol to membrane. It is concluded that apoptosis induced by bufalin is associated with downregulation of protein expression, dephosphorylation, and cleavage of Bcl-2 in HL-60 cells.