Differential expression of protein kinase C subtypes during ginsenoside Rh2-lnduced apoptosis in SK-N-BE(2) and C6Bu-1 cells

Anticancer property of ginsenoside Rh2 from ginseng

Ginseng has been used as a well-known traditional Chinese medicine since ancient times. Ginsenosides as its main active constituents possess a broad scope of pharmacological properties including stimulating immune function, enhancing cardiovascular health, increasing resistance to stress, improving memory and learning, developing social functioning and mental health in normal persons, and chemotherapy. Ginsenoside Rh2 (Rh2) is one of the major bioactive ginsenosides from Panax ginseng. When applied to cancer treatment, Rh2 not only exhibits the anti-proliferation, anti-invasion, anti-metastasis, induction of cell cycle arrest, promotion of differentiation, and reversal of multi-drug resistance activities against multiple tumor cells, but also alleviates the side effects after chemotherapy or radiotherapy. In the past decades, nearly 200 studies on Rh2 in the treatment of cancer have been published, however no specific reviews have been conducted by now. So the purpose of this review is to provide a systematic summary and analysis of the anticancer effects and the potential mechanisms of Rh2 extracted from Ginseng then give a future prospects about it. In the end of this paper the metabolism and derivatives of Rh2 also have been documented.

Enzastaurin inhibits ABCB1-mediated drug efflux independently of effects on protein kinase C signalling and the cellular p53 status

The PKCβ inhibitor enzastaurin was tested in parental neuroblastoma and rhabdomyosarcoma cell lines, their vincristine-resistant sub-lines, primary neuroblastoma cells, ABCB1-transduced, ABCG2-transduced, and p53-depleted cells. Enzastaurin IC₅₀s ranged from 3.3 to 9.5 μM in cell lines and primary cells independently of the ABCB1, ABCG2, or p53 status. Enzastaurin 0.3125 μM interfered with ABCB1-mediated drug transport. PKCα and PKCβ may phosphorylate and activate ABCB1 under the control of p53. However, enzastaurin exerted similar effects on ABCB1 in the presence or absence of functional p53. Also, enzastaurin inhibited PKC signalling only in concentrations ≥ 1.25 μM. The investigated cell lines did not express PKCβ. PKCα depletion reduced PKC signalling but did not affect ABCB1 activity. Intracellular levels of the fluorescent ABCB1 substrate rhodamine 123 rapidly decreased after wash-out of extracellular enzastaurin, and enzastaurin induced ABCB1 ATPase activity resembling the ABCB1 substrate verapamil. Computational docking experiments detected a direct interaction of enzastaurin and ABCB1. These data suggest that enzastaurin directly interferes with ABCB1 function. Enzastaurin further inhibited ABCG2-mediated drug transport but by a different mechanism since it reduced ABCG2 ATPase activity. These findings are important for the further development of therapies combining enzastaurin with ABC transporter substrates.

p53-dependent Fas expression is critical for Ginsenoside Rh2 triggered caspase-8 activation in HeLa cells

We have recently reported that Ginsenoside Rh2 (G-Rh2) induces the activation of two initiator caspases, caspase-8 and caspase-9 in human cancer cells. However, the molecular mechanism of its death-inducing function remains unclear. Here we show that G-Rh2 stimulated the activation of both caspase-8 and caspase-9 simultaneously in HeLa cells. Under G-Rh2 treatment, membrane death receptors Fas and TNFR1 are remarkably upregulated. However, the induced expression of Fas but not TNFR1 was contributed to the apoptosis process. Moreover, significant increases in Fas expression and caspase-8 activity temporally coincided with an increase in p53 expression in p53-non-mutated HeLa and SK-HEP-1 cells upon G-Rh2 treatment. In contrast, Fas expression and caspase-8 activity remained constant with G-Rh2 treatment in p53-mutated SW480 and PC-3 cells. In addition, siRNA-mediated knockdown of p53 diminished G-Rh2-induced Fas expression and caspase-8 activation. These results indicated that G-Rh2-triggered extrinsic apoptosis relies on p53-mediated Fas over-expression. In the intrinsic apoptotic pathway, G-Rh2 induced strong and immediate translocation of cytosolic BAK and BAX to the mitochondria, mitochondrial cytochrome c release, and subsequent caspase-9 activation both in HeLa and in SW480 cells. p53-mediated Fas expression and subsequent downstream caspase-8 activation as well as p53-independent caspase-9 activation all contribute to the activation of the downstream effector caspase-3/-7, leading to tumor cell death. Taken together, we suggest that G-Rh2 induces cancer cell apoptosis in a multi-path manner and is therefore a promising candidate for anti-tumor drug development.

A new platinum(II) compound anticancer drug candidate with selective cytotoxicity for breast cancer cells

[Pt(O,O′-acac)(γ-acac)(DMS)] (PtAcD) is able to induce apoptosis in various human cancer cells, including the cisplatin-resistant human breast carcinoma MCF-7 cells. Here, to confirm that PtAcD has the potentiality for therapeutic intervention, we studied its effects in primary cultured epithelial breast cells obtained from cancers and also from the corresponding histologically proven non-malignant tissue adjacent to the tumor. We demonstrated that PtAcD (1) is more cytotoxic in cancer than in normal breast cells; (2) activated NAD(P)H oxidase, leading to PKC-ζ and PKC-α tanslocations; (3) activated antiapoptotic pathways based on the PKC-α, ERK1/2 and Akt kinases; (4) activated PKC-ζ and, only in cancer cell PKC-δ, responsible for the sustained phosphorylation of p38 and JNK1/2, kinases both of which are involved in the mitochondrial apoptotic process. Moreover, crosstalk between ERK/Akt and JNK/p38 pathways affected cell death and survival in PtAcD-treated breast cell. In conclusion, this study adds and extends data that highlight the pharmacological potential of PtAcD as an anti breast cancer drug.

A novel oral dosage formulation of the ginsenoside aglycone protopanaxadiol exhibits therapeutic activity against a hormone-insensitive model of prostate cancer

This study focuses on determining the pharmacokinetics, biodistribution, and efficacy of the ginsenoside aglycone protopanaxadiol (aPPD) administered as a single agent in a novel oral dosage formulation. To obtain these data and to characterize the stability of aPPD, appropriate analytical assay development was carried out. The solubility and stability of aPPD were determined, and the compound was formulated for oral gavage. aPPD levels in blood and tissues following oral administration to nu/nu nude mice were determined using liquid chromatography-mass spectrometry/mass spectrometry. The efficacy of aPPD was determined upon oral administration to nu/nu nude mice bearing PC-3 human prostate cancer xenograft tumors. Immunohistochemical analysis of tumor tissues was performed to establish apoptotic indices and Ki-67 expression as markers of proliferation. The maximum solubility of aPPD in ethanol was 68.4 mg/ml. aPPD administered at a dose of 70 mg/kg yielded a T(max) of approximately 40 min and a C(max) value of 3.9 ± 1.4 μg/ml, and no toxicity was observed. aPPD accumulated largely in the stomach and small intestine and was also present in the brain. This dose engendered a significant delay in PC-3 tumor growth, an increase in apoptotic index, and a decrease in Ki-67 levels. We have shown that aPPD is a stable compound that can be formulated for oral gavage. Pharmacokinetic studies demonstrate the ability of this compound to be absorbed after oral administration. Future studies will assess the activity and pharmacokinetics of aPPD when administered in combination with standard chemotherapy.

Current evaluation of the millennium phytomedicine- ginseng (II): Collected chemical entities, modern pharmacology, and clinical applications emanated from traditional Chinese medicine

This review, a sequel to part 1 in the series, collects about 107 chemical entities separated from the roots, leaves and flower buds of Panax ginseng, quinquefolius and notoginseng, and categorizes these entities into about 18 groups based on their structural similarity. The bioactivities of these chemical entities are described. The 'Yin and Yang' theory and the fundamentals of the 'five elements' applied to the traditional Chinese medicine (TCM) are concisely introduced to help readers understand how ginseng balances the dynamic equilibrium of human physiological processes from the TCM perspectives. This paper concerns the observation and experimental investigation of biological activities of ginseng used in the TCM of past and present cultures. The current biological findings of ginseng and its medical applications are narrated and critically discussed, including 1) its antihyperglycemic effect that may benefit type II diabetics; in vitro and in vivo studies demonstrated protection of ginseng on beta-cells and obese diabetic mouse models. The related clinical trial results are stated. 2) its aphrodisiac effect and cardiovascular effect that partially attribute to ginseng's bioactivity on nitric oxide (NO); 3) its cognitive effect and neuropharmacological effect that are intensively tested in various rat models using purified ginsenosides and show a hope to treat Parkinson's disease (PD); 4) its uses as an adjuvant or immunotherapeutic agent to enhance immune activity, appetite and life quality of cancer patients during their chemotherapy and radiation. Although the apoptotic effect of ginsenosides, especially Rh2, Rg3 and Compound K, on various tumor cells has been shown via different pathways, their clinical effectiveness remains to be tested. This paper also updates the antioxidant, anti-inflammatory, anti-apoptotic and immune-stimulatory activities of ginseng, its ingredients and commercial products, as well as common side effects of ginseng mainly due to its overdose, and its pharmacokinetics.

Molecular mechanisms of ginsenoside Rh2-mediated G1 growth arrest and apoptosis in human lung adenocarcinoma A549 cells

Ginsenoside Rh2 (Rh2), a purified ginseng saponin, has been shown to have antiproliferative effects in certain cancer cell types. However, the molecular mechanisms of Rh2 on cell growth and death have not been fully clarified. In this study, the antiproliferative effect of Rh2 in human lung adenocarcinoma A549 cells was investigated. Treatment of A549 cells with 30 mug/ml Rh2 resulted in G(1) phase arrest, followed by progression to apoptosis. This Rh2-mediated G(1) arrest was accompanied by downregulation of the protein levels and kinase activities of cyclin-D1, cyclin-E and Cdk6, and the upregulation of pRb2/p130. In addition, Rh2-induced apoptosis was confirmed by TUNEL assay and DNA fragmentation analysis. Administration of Rh2 caused an increase in the expression levels of TRAIL-RI (DR4) death receptor but did not alter the levels of other death receptors or Bcl-2 family molecules. Furthermore, the Rh2-induced apoptosis was significantly inhibited by DR4:Fc fusion protein, which inhibits TRAIL-DR4-mediated apoptosis. In addition, caspase-2, caspase-3 and caspase-8 were highly activated upon Rh2 treatment. Inhibitors of caspase-2, caspase-3 and caspase-8 markedly prevented the cell death induced by Rh2. Inhibitor of caspase-8 significantly inhibited the activation of caspase-2, caspase-3 and caspase-8. These observations indicate that multiple G(1)-related cell cycle regulatory proteins are regulated by Rh2 and contribute to Rh2-induced G(1) growth arrest. The increase in the expression level of DR4 death receptor may play a critical role in the initiation of Rh2-triggered apoptosis, and the activation of the caspase-8/caspase-3 cascade acts as the executioner of the Rh2-induced death process.

Ginsenoside Rh2 induces apoptosis via activation of caspase-1 and -3 and up-regulation of Bax in human neuroblastoma

In human neuroblastoma SK-N-BE(2) cells undergoing apoptotic death induced by ginsenoside Rh2, a dammarane glycoside that was isolated from Panax ginseng C. A. Meyer, caspase-1 and caspase-3 were activated. The expression of Bax was increased in the cells treated with ginsenoside Rh2, whereas Bcl-2 expression was not altered. Treatment with caspase-1 inhibitor, Ac-YVAD-CMK, or caspase-3 inhibitor, Z-DEVD-FMK, partially inhibited ginsenoside Rh2-induced cell death but almost suppressed the cleavage of the 116 kDa PARP into a 85 kDa fragment. When the levels of p53 were examined in this process, p53 accumulated rapidly in the cells treated early with ginsenoside Rh2. These results suggest that activation of caspase-1 and -3 and the up-regulation of Bax are required in order for apoptotic death of SK-N-BE(2) cells to be induced by ginsenoside Rh2, and p53 plays an important role in the pathways to promote apoptosis.

Effects of ginsenosides Rg3 and Rh2 on the proliferation of prostate cancer cells

Ginseng has an anti-cancer effect in several cancer models. This study was to characterize active constituents of ginseng and their effects on proliferation of prostate cancer cell lines, LNCaP and PC3. Cell proliferation was measured by [3H]thymidine incorporation, the intracellular calcium concentration by a dual-wavelength spectrophotometer system, effects on mitogen-activated protein (MAP) kinases by Western blotting, and cell attachment and morphologic changes were observed under a microscope. Among 11 ginsenosides tested, ginsenosides Rg3 and Rh2 inhibited the proliferation of prostate cancer cells. EC50s of Rg3 and Rh2 on PC3 cells were 8.4 microM and 5.5 microM, respectively, and 14.1 microM and 4.4 microM on LNCaP cells, respectively. Both ginsenosides induced cell detachment and modulated three modules of MAP kinases activities differently in LNCaP and PC3 cells. These results suggest that ginsenosides Rg3 and Rh2-induced cell detachment and inhibition of the proliferation of prostate cancer cells may be associated with modulation of three modules of MAP kinases.

Protein kinase C-zeta modulates thromboxane A(2)-mediated apoptosis in adult ventricular myocytes via Akt

We hypothesized that thromboxane A(2) (TxA(2)) receptor stimulation directly induces apoptosis in adult cardiac myocytes. To investigate this, we exposed cultured adult rat ventricular myocytes (ARVM) to a TxA(2) mimetic [1S-[1alpha,2alpha(Z),3beta(1E,3S*),4alpha]]-7-[3-[3-hydroxy-4-(4-iodophenoxy)-1-butenyl]-7-oxabicyclo[2.2.1]hept-2-yl]-5-heptenoic acid (I-BOP) for 24 h. Stimulation with I-BOP induced apoptosis in a dose-dependent manner and was completely prevented by a TxA(2) receptor antagonist, SQ-29548. We further investigated the role of protein kinase C (PKC) in this process. TxA(2) stimulation resulted in membrane translocation of PKC-zeta but not PKC-alpha, -betaII, -delta, and -epsilon at 3 min and 1 h. The activation of PKC-zeta by I-BOP was confirmed using an immune complex kinase assay. Treatment of ARVM with a cell-permeable PKC-zeta pseudosubstrate peptide (zeta-PS) significantly attenuated apoptosis by I-BOP. In addition, I-BOP treatment decreased baseline Akt activity and its decrease was reversed by treatment with zeta-PS. The inhibition of phosphatidylinositol 3-kinase upstream of Akt by wortmannin or LY-294002 abolished the antiapoptotic effect of zeta-PS. Therefore, our results suggest that the activation of PKC-zeta modulates TxA(2) receptor-mediated apoptosis at least, in part, through Akt activity in adult cardiac myocytes.

Anticarcinogenic effect and enhancement of metastatic potential of BALB/c 3T3 cells by ginsenoside Rh(2)

It has been reported that ginsenoside Rh(2), a purified ginseng saponin with a dammarane skeleton, has anticarcinogenic effects on mammalian cells. To determine the significance of these effects on multistage carcinogenesis, we utilized the BALB / c 3T3 cell system. In an in vitro two-stage neoplastic transformation assay, the initiating activity of 3-methylcholanthrene (3-MCA) was suppressed by Rh(2) (>or= 1 x 10(-5) M) in both BALB / c 3T3 A31-1-1 cells and the more carcinogen-susceptible variant A31-1-13 cells. The suppressive effects in this concentration range were thought to be caused by suppression of DNA replication via indirect Cdk2 inhibition. On the other hand, the promotion steps of both the target cells were not affected by Rh(2) even if the transformation frequency was enhanced by a tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA). To examine the other effects of Rh(2) on carcinogenesis, we turned our attention to the metastatic phenotype. Using metastatic src-transformed A31-1-1 cells, we found that Rh(2) augmented the metastatic potential in an experimental metastasis assay. These data indicate that Rh(2) has diverse effects on the expression of the transformed phenotype in BALB / c 3T3 cells, but support the idea that growth suppression is likely to be a major mechanism of the anticarcinogenic effects of Rh(2).