Antroquinonol displays anticancer potential against human hepatocellular carcinoma cells: a crucial role of AMPK and mTOR pathways. Biochem Pharmacol. 2010;79:162-171. [PMID: 19723512 DOI: 10.1016/j.bcp.2009.08.022]

Antroquinonol from ethanolic extract of mycelium of Antrodia cinnamomea protects hepatic cells from ethanol-induced oxidative stress through Nrf-2 activation

AIM OF THE STUDY

In recent years, the medicinal mushroom Antrodia cinnamomea, known as "niu-chang chih" has received much attention with regard to its possible health benefits; especially its hepatoprotective effects against various drugs, toxins, and alcohol induced liver diseases. However, the molecular mechanism underlying this protective effect of Antrodia cinnamomea and its active compound antroquinonol was poorly understood. In the present study we evaluated to understand the hepatoprotective efficacy of antroquinonol and ethanolic extracts of mycelia of Antrodia cinnamomea (EMAC) in vitro and in vivo.

MATERIALS AND METHODS

The protective mechanism of antroquinonol and EMAC against ethanol-induced oxidative stress was investigated in cultured human hepatoma HepG2 cells and ICR mice model, respectively. HepG2 cells were pretreated with antroquinonol (1-20μM) and oxidative stress was induced by ethanol (100mM). Meanwhile, male ICR mice were pretreated with EMAC for 10 days and hepatotoxicity was generated by the addition of ethanol (5g/kg). Hepatic enzymes, cytokines and chemokines were determined using commercially available assay kits. Western blotting and real-time PCR were subjected to analyze HO-1 and Nr-2 expression. EMSA was performed to monitor Nrf-2 ARE binding activity. Possible changes in hepatic lesion were observed using histopathological analysis.

RESULTS

Antroquinonol pretreatment significantly inhibited ethanol-induced AST, ALT, ROS, NO, MDA production and GSH depletion in HepG2 cells. Western blot and RT-PCR analysis showed that antroquinonol enhanced Nrf-2 activation and its downstream antioxidant gene HO-1 via MAPK pathway. This mechanism was then confirmed in vivo in an acute ethanol intoxicated mouse model: serum ALT and AST production, hepatocellular lipid peroxidation and GSH depletion was prevented by EMAC in a dose-dependent manner. EMAC significantly enhanced HO-1 and Nrf-2 activation via MAPKs consistent with in vitro studies. Ethanol-induced hepatic swelling and hydropic degeneration of hepatocytes was significantly inhibited by EMAC in a dose-dependent manner.

CONCLUSIONS

These results provide a scientific basis for the hepatoprotective effects of Antrodia cinnamomea. Data also imply that antroquinonol, a potent bioactive compound may be responsible for the hepatoprotective activity of Antrodia cinnamomea. Moreover, the present study highly supported our traditional knowledge that Antrodia cinnamomea as a potential candidate for the treatment of alcoholic liver diseases.

Antroquinonol reduces oxidative stress by enhancing the Nrf2 signaling pathway and inhibits inflammation and sclerosis in focal segmental glomerulosclerosis mice

Oxidative stress, inflammation, and fibrosis are involved in the development and progression of focal segmental glomerulosclerosis (FSGS), a common form of idiopathic nephrotic syndrome that represents a therapeutic challenge because it has a poor response to steroids. Antroquinonol (Antroq), a purified compound, is a major active component of a mushroom, namely Antrodia camphorata, that grows in the camphor tree in Taiwan, and it has inhibitory effects on nitric oxide production and inflammatory reactions. We hypothesized that Antroq might ameliorate FSGS renal lesions by modulating the pathogenic pathways of oxidative stress, inflammation, and glomerular sclerosis in the kidney. We demonstrate that Antroq significantly (1) attenuates proteinuria, renal dysfunction, and glomerulopathy, including epithelial hyperplasia lesions and podocyte injury; (2) reduces oxidative stress, leukocyte infiltration, and expression of fibrosis-related proteins in the kidney; (3) increases renal nuclear factor E2-related factor 2 (Nrf2) and glutathione peroxidase activity; and (4) inhibits renal nuclear factor-κB (NF-κB) activation and decreases levels of transforming growth factor (TGF)-β1 in serum and kidney tissue in a mouse FSGS model. Our data suggest that Antroq might be a potential therapeutic agent for FSGS, acting by boosting Nrf2 activation and suppressing NF-κB-dependent inflammatory and TGF-β1-mediated fibrosis pathways in the kidney.

The targets of curcumin

Curcumin (diferuloylmethane), an orange-yellow component of turmeric or curry powder, is a polyphenol natural product isolated from the rhizome of the plant Curcuma longa. For centuries, curcumin has been used in some medicinal preparation or used as a food-coloring agent. In recent years, extensive in vitro and in vivo studies suggested curcumin has anticancer, antiviral, antiarthritic, anti-amyloid, antioxidant, and anti-inflammatory properties. The underlying mechanisms of these effects are diverse and appear to involve the regulation of various molecular targets, including transcription factors (such as nuclear factor-kB), growth factors (such as vascular endothelial cell growth factor), inflammatory cytokines (such as tumor necrosis factor, interleukin 1 and interleukin 6), protein kinases (such as mammalian target of rapamycin, mitogen-activated protein kinases, and Akt) and other enzymes (such as cyclooxygenase 2 and 5 lipoxygenase). Thus, due to its efficacy and regulation of multiple targets, as well as its safety for human use, curcumin has received considerable interest as a potential therapeutic agent for the prevention and/or treatment of various malignant diseases, arthritis, allergies, Alzheimer's disease, and other inflammatory illnesses. This review summarizes various in vitro and in vivo pharmacological aspects of curcumin as well as the underlying action mechanisms. The recently identified molecular targets and signaling pathways modulated by curcumin are also discussed here.

A unique P-glycoprotein interacting agent displays anticancer activity against hepatocellular carcinoma through inhibition of GRP78 and mTOR pathways

P-glycoprotein (P-gp) overexpression has been demonstrated in many malignancies being a predominant mechanism by which cancer cells develop multidrug resistance. Several categories of P-gp inhibitors have been demonstrated to potentiate anticancer effect induced by cancer chemotherapeutic drugs through competitive inhibition of P-gp pumping activity. Few studies show the agent that selectively acts on P-gp and, by itself, causes cell apoptosis while remain P-gp-deficient cells unaffected. KNG-I-322, a desmosdumotin B derivative, displayed a direct interaction with P-gp and demonstrated selective anti-proliferative and apoptotic activities in P-gp overexpressed Hep3B/VIN other than P-gp-deficient Hep3B cells. KNG-I-322 induced an inhibitory effect on the phosphorylation of mTOR(Ser2448), p70S6K(Thr389) and 4E-BP(Thr37/46) in Hep3B/VIN but not Hep3B cells. The inhibition was fully blocked by the knockdown of P-gp using siRNA techniques. Notably, the P-gp inhibitor, verapamil, also directly interacted with P-gp but significantly diminished KNG-I-322-induced anti-proliferative activity. After the mechanism study, the data showed that KNG-I-322 induced a dramatic down-regulation of GRP78 expression, which was significantly inhibited by verapamil and completely diminished by the knockdown of P-gp. The protein profile analysis of detergent resistant membranes showed that upon the stimulation by KNG-I-322, the level of P-gp expression in non-raft fractions was dramatically increased and, concomitantly, the GRP78 expression was significantly decreased. Taken together, the data suggest that KNG-I-322 induces anticancer activity in Hep3B/VIN cells through a direct interaction with P-gp, leading to the inhibition of mTOR pathways and the induction of GRP78 down-regulation. The data support that KNG-I-322 is a selective anticancer agent against P-gp-overexpressed other than P-gp-deficient cancer cells.

Exogenous cell-permeable C6 ceramide sensitizes multiple cancer cell lines to Doxorubicin-induced apoptosis by promoting AMPK activation and mTORC1 inhibition

New chemotherapy-enhancing strategies are needed for better cancer therapy. Previous studies suggest that exogenous cell-permeable C6 ceramide may be a useful adjunct to the anti-tumor effects of chemotherapeutic agents (such as Taxol) against multiple cancers. Here we demonstrate that exogenous cell-permeable C6 ceramide largely sensitizes multiple progressive cancer cell lines to Doxorubicin-induced cell death and apoptosis. We found for the first time that Doxorubicin induces AMP-activated protein kinase (AMPK) activation in a reactive oxygen species-dependent manner. Activation of AMPK contributes to Doxorubicin-induced cancer cell death and apoptosis. Inhibition of AMPK by small interfering RNA knockdown or a pharmacological inhibitor reduces Doxorubicin-induced cancer cell apoptosis, whereas AMPK activator AICAR enhances it. Importantly, we found that C6 ceramide largely enhances Doxorubicin-induced activation of AMPK, which leads to mTOR complex 1 inhibition and chemo-sensitization. Our data suggest that the combination of C6 ceramide with traditional chemotherapy drugs such as Doxorubicin may have the potential to be used as a new therapeutic intervention against multiple cancers.

Cell cycle progression or translation control is not essential for vesicular stomatitis virus oncolysis of hepatocellular carcinoma

The intrinsic oncolytic specificity of vesicular stomatitis virus (VSV) is currently being exploited to develop alternative therapeutic strategies for hepatocellular carcinoma (HCC). Identifying key regulators in diverse transduction pathways that define VSV oncolysis in cancer cells represents a fundamental prerequisite to engineering more effective oncolytic viral vectors and adjusting combination therapies. After having identified defects in the signalling cascade of type I interferon induction, responsible for attenuated antiviral responses in human HCC cell lines, we have now investigated the role of cell proliferation and translation initiation. Cell cycle progression and translation initiation factors eIF4E and eIF2Bε have been recently identified as key regulators of VSV permissiveness in T-lymphocytes and immortalized mouse embryonic fibroblasts, respectively. Here, we show that in HCC, decrease of cell proliferation by cell cycle inhibitors or siRNA-mediated reduction of G(1) cyclin-dependent kinase activities (CDK4) or cyclin D1 protein expression, do not significantly alter viral growth. Additionally, we demonstrate that translation initiation factors eIF4E and eIF2Bε are negligible in sustaining VSV replication in HCC. Taken together, these results indicate that cellular proliferation and the initiation phase of cellular protein synthesis are not essential for successful VSV oncolysis of HCC. Moreover, our observations indicate the importance of cell-type specificity for VSV oncolysis, an important aspect to be considered in virotherapy applications in the future.

Inhibition of epidermal growth factor receptor signaling by Saussurea involucrata, a rare traditional Chinese medicinal herb, in human hormone-resistant prostate cancer PC-3 cells

Prostate carcinoma is the most frequently diagnosed malignancy and the second leading cause of death of men in the United States. To date, no effective therapeutic treatment allows abrogation of the progression of prostate cancer to more invasive forms. In this study, we identified Saussurea involucrata Kar. et Kir., a rare traditional Chinese medicinal herb, as a potential agent for androgen-independent prostate cancer patients and investigated its biological mechanism as an antineoplastic agent. S. involucrata caused a concentration- and time-dependent inhibition of cell proliferation in human hormone-resistant prostate cancer PC-3 cells. Moreover, in vitro studies in a panel of several types of human cancer cell lines revealed that S. involucrata inhibited cell proliferation with high potency. To evaluate the bioactive compounds, we successively extracted the S. involucrata with fractions of methanol (SI-1), ethyl acetate (SI-2), n-butanol (SI-3), and water (SI-4). Among these extracts, SI-2 contains the most effective bioactivity. SI-2 treatment resulted in significant time-dependent growth inhibition together with G1 phase cell cycle arrest and apoptosis in PC3 cells. In addition, SI-2 treatment strongly induced p21WAF1/CIP and p27KIP1 expression, independent of the p53 pathway, and downregulated expression of cyclin D1 and cyclin-dependent kinase 4 (CDK4). SI-2 treatment increased levels of Bax, cytochrome c, activated caspase-3, and active caspase-9 and decreased Bcl-2 expression level. One of the major targets for the therapy in prostate cancer can be epidermal growth factor receptor (EGFR). SI-2 markedly reduced phosphorylation of EGFR and inhibited activation of AKT and STAT3. Moreover, p.o. administration of SI-2 induced a dose-dependent inhibition of PC-3 tumor growth in vivo. In summary, our study identifies S. involucrata as an effective inhibitor of EGFR signaling in human hormone-resistant prostate cancer PC-3 cells. We suggest that S. involucrata could be developed as an agent for the management of EGFR-positive human cancers.