Pamidronate induced anti-proliferative, apoptotic, and anti-migratory effects in hepatocellular carcinoma

Unusual Partners: γδ-TCR-Based T Cell Therapy in Combination with Oncolytic Virus Treatment for Diffuse Midline Gliomas

Due to the minimal survival benefits of existing therapies for pediatric diffuse midline glioma (DMG) patients, new therapeutic modalities are being investigated. Immunotherapies such as CAR-T cells and oncolytic viruses (OVs) are part of these efforts, as evidenced by the increasing number of clinical trials. αβ T cells engineered with a high-affinity γ9δ2 T-cell receptor (TEGs) are immune cells designed to target metabolic changes in malignant or virally infected cells via BTN2A1 and BTN3A. Because the expression of BTN2A1 and BTN3A can be altered in tumor and infected cells, combining TEGs and OVs could potentially enhance the anti-tumor response. We investigated this hypothesis in the following study. We demonstrate that TEGs can indeed target DMG, which expresses BTN2A1 and BTN3A at varying levels, and that OVs can further enhance the expression of BTN3A-but not BTN2A1-in DMG. Functionally, TEGs killed DMG cell cultures, and this killing was further increased after OV infection of the DMGs with either adenovirus Δ24-RGD or reovirus R124 under suboptimal conditions. However, this additive effect was lost when γ9δ2 TCR-ligand interaction was boosted by pamidronate. This study demonstrates the additive effect of combining OVs and Vγ9Vδ2 TCR-engineered immune cells under suboptimal conditions and supports a combination strategy to enhance the efficacy of both therapeutic modalities.

Metabolism as a New Avenue for Hepatocellular Carcinoma Therapy

Hepatocellular carcinoma is today the sixth leading cause of cancer-related death worldwide, despite the decreased incidence of chronic hepatitis infections. This is due to the increased diffusion of metabolic diseases such as the metabolic syndrome, diabetes, obesity, and nonalcoholic steatohepatitis (NASH). The current protein kinase inhibitor therapies in HCC are very aggressive and not curative. From this perspective, a shift in strategy toward metabolic therapies may represent a promising option. Here, we review current knowledge on metabolic dysregulation in HCC and therapeutic approaches targeting metabolic pathways. We also propose a multi-target metabolic approach as a possible new option in HCC pharmacology.

Cellular Genome-Scale Metabolic Modeling Identifies New Potential Drug Targets Against Hepatocellular Carcinoma

Genome-scale metabolic modeling (GEM) is one of the key approaches to unpack cancer metabolism and for discovery of new drug targets. In this study, we report the Transcriptional Regulated Flux Balance Analysis-CORE (TRFBA-), an algorithm for GEM using key growth-correlated reactions using hepatocellular carcinoma (HCC), an important global health burden, as a case study. We generated a HepG2 cell-specific GEM by integrating this cell line transcriptomic data with a generic human metabolic model to forecast potential drug targets for HCC. A total of 108 essential genes for growth were predicted by the TRFBA-CORE. These genes were enriched for metabolic pathways involved in cholesterol, sterol, and steroid biosynthesis. Furthermore, we silenced a predicted essential gene, 11-beta dehydrogenase hydroxysteroid type 2 (HSD11B2), in HepG2 cells resulting in a reduction in cell viability. To further identify novel potential drug targets in HCC, we examined the effect of nine drugs targeting the essential genes, and observed that most drugs inhibited the growth of HepG2 cells. Some of these drugs in this model performed better than Sorafenib, the first-line therapeutic against HCC. A HepG2 cell-specific GEM highlights sterol metabolism to be essential for cell growth. HSD11B2 downregulation results in lower cell growth. Most of the compounds, selected by drug repurposing approach, show a significant inhibitory effect on cell growth in a wide range of concentrations. These findings offer new molecular leads for drug discovery for hepatic cancer while also illustrating the importance of GEM and drug repurposing in cancer therapeutics innovation.

Targeting Lipid Metabolism in Liver Cancer

Cancer cells are highly dependent on different metabolic pathways for sustaining their survival, growth, and proliferation. Lipid metabolism not only provides the energetic needs of the cells but also provides the raw material for cellular growth and the signaling molecules for many oncogenic pathways. Mainly processed in the liver, lipids play an essential role in the physiology of this organ and in the pathological progression of many diseases such as metabolic syndrome and hepatocellular carcinoma (HCC). The progression of HCC is associated with inflammation and complex metabolic reprogramming, and its prognosis remains poor because of the lack of effective therapies despite many years of dedicated research. Defects in hepatic lipid metabolism induce abnormal gene expression and rewire many cellular pathways involved in oncogenesis and metastasis, implying that interfering with lipid metabolism within the tumor and the surrounding microenvironment may be a novel therapeutic approach for treating liver cancer patients. Therefore, this review focuses on the latest advances in drugs targeting lipid metabolism and leading to promising outcomes in preclinical studies and some ongoing clinical trials.

Inhibition of growth and migration of cholangiocarcinoma cells by pamidronate

Pamidronate has been hypothesized to effectively inhibit cancer cell growth and metastasis in bone tissue. Furthermore, pamidronate (Pami) exerts various direct effects against several cancer cell types, including growth and migration. The present study aimed to determine the underlying mechanism of Pami's effect on the proliferation and migration of cholangiocarcinoma (CCA) cells. KKU-100 cells were used to determine the effects of Pami on cell death and migration. The following were assessed: Sulforhodamine B, colony formation, apoptosis via flow cytometry, reactive oxygen species (ROS) production and caspase-3 activity. In addition, the effects of the test compound on the mevalonate (MVA) signaling pathway were determined via western blotting and reverse transcription-quantitative PCR. Cell migration was observed via wound healing, Matrigel and gelatin zymography. The results indicated that Pami induced CCA cell death and inhibited colony formation in a dose-dependent manner, with IC₅₀ values of 444.67±44.05 µM at 24 h and 147.33±17.01 µM at 48 h. Furthermore, Pami treatment suppressed colony formation at a lower concentration than growth inhibition with IC₅₀ values of 5.36±0.31 µM. The mechanism of growth inhibition was determined to potentially be associated with increased ROS generation and stimulated caspase-3 enzyme activity, leading to the induction of apoptosis. Furthermore, Pami treatment interfered with the MVA signaling pathway by reducing Rac1 protein levels and modulating the gene and protein expression of RhoA. Furthermore, Pami suppressed CCA cell migration by decreasing matrix metalloproteinase (MMP)2 and MMP9 levels. Additionally, Pami treatment activated CCA cell death and inhibited CCA migration at low concentrations. Pami significantly decreased the protein expression levels of Rac1 in the MVA signaling pathway and may therefore be beneficial for developing a novel chemotherapeutic method for CCA.

Antiproliferative and antimigratory activities of bisphosphonates in human breast cancer cell line MCF-7

Bisphosphonates (BPs) are antiresorptive drugs that act as effective inhibitors of cancer cell proliferation. However, not all bisphosphonates are equally effective against breast cancer cells in vitro. The present study investigated the extent to which three BPs decrease the viability of MCF-7 human breast cancer cells, stimulate cell apoptosis and inhibit cell migration by modulating proteins in the mevalonate pathway. The three BPs exerted direct anticancer effects against MCF-7 cells in a dose- and time-dependent manner, with pamidronate demonstrating the highest efficacy. In addition, the BPs inhibited colony formation ability. The activity of BPs against MCF-7 cells was inhibited by the mevalonate product geranylgeranyl pyrophosphate, which was potentiated by doxorubicin. It was also identified that BPs modulated Ras-related C3 botulinum toxin substrate 1, Ras homolog gene family member A and cell division control protein 42 homolog gene expression. Consistent with the observed growth inhibitory effects, BPs also inhibited the cell cycle by promoting G1 phase arrest and the downregulation of cyclin D1 and upregulation of p21. Additionally, BPs were revealed to induce reactive oxygen species expression, caspase-3 activity and increase the mitochondrial transmembrane potential, which was associated with apoptosis. BP-induced cancer cell apoptosis was detected by acridine orange/ethidium bromide staining and flow cytometry analysis, and was identified to be associated with the induction of caspase-3 and cytochrome c protein expression. Furthermore, BPs significantly decreased cancer cell migration in a dose-dependent manner and reduced matrix metallopeptidase-9 protein expression. In summary, the current study demonstrated that BPs exhibited a direct anticancer effect and an antimigratory effect on MCF-7 cells. These findings suggest that BPs may be developed as a therapeutic option for breast cancer and may serve as sensitizing chemotherapeutic agents.

Aberrant Metabolism in Hepatocellular Carcinoma Provides Diagnostic and Therapeutic Opportunities

Hepatocellular carcinoma (HCC) accounts for over 80% of liver cancer cases and is highly malignant, recurrent, drug-resistant, and often diagnosed in the advanced stage. It is clear that early diagnosis and a better understanding of molecular mechanisms contributing to HCC progression is clinically urgent. Metabolic alterations clearly characterize HCC tumors. Numerous clinical parameters currently used to assess liver functions reflect changes in both enzyme activity and metabolites. Indeed, differences in glucose and acetate utilization are used as a valid clinical tool for stratifying patients with HCC. Moreover, increased serum lactate can distinguish HCC from normal subjects, and serum lactate dehydrogenase is used as a prognostic indicator for HCC patients under therapy. Currently, the emerging field of metabolomics that allows metabolite analysis in biological fluids is a powerful method for discovering new biomarkers. Several metabolic targets have been identified by metabolomics approaches, and these could be used as biomarkers in HCC. Moreover, the integration of different omics approaches could provide useful information on the metabolic pathways at the systems level. In this review, we provided an overview of the metabolic characteristics of HCC considering also the reciprocal influences between the metabolism of cancer cells and their microenvironment. Moreover, we also highlighted the interaction between hepatic metabolite production and their serum revelations through metabolomics researches.

Targeting the mevalonate pathway is a novel therapeutic approach to inhibit oncogenic FoxM1 transcription factor in human hepatocellular carcinoma

Dysregulation of cell metabolism is a hallmark of cancer. The mevalonate pathway in lipid metabolism has been implicated as a potential target of cancer therapy for hepatocellular carcinoma (HCC). The role of the Forkhead Box M1 (FoxM1) transcription factor in HCC development has been well documented, however, its involvement in cancer metabolism of HCC has not been fully determined. Here, we hypothesized that FoxM1 is involved in the mevalonate pathway of cholesterol biosynthesis in HCC. Inhibition of the mevalonate pathway by statins, inhibitors of 3-hydroxy-3-methylglutaryl CoA reductase (HMGCR), resulted in reduced expression of FoxM1 and increased cell death in human hepatoma cells. Re-exposure of mevalonate, a product of HMGCR, restored these effects. Likewise, knockdown of HMGCR reduced FoxM1 expression, indicating that FoxM1 expression was regulated by the mevalonate pathway in HCC. Mechanistically, protein geranylgeranylation was found to be responsible for FoxM1 expression and geranylgeranylated proteins, including RhoA, Rac1 or Cdc42, were shown to be involved in this process. In surgically resected human HCC tissues, the gene expression of FoxM1 had a positive correlation with that of the mevalonate pathway-related genes, such as HMGCR or sterol regulatory element-binding protein 2 (SREBP2). Furthermore, the gene expression of FoxM1 along with that of HMGCR or SREBP2 defined prognosis of HCC patients, suggesting the clinical significance of the mevalonate-FoxM1 pathway in human HCC. Our data indicate that FoxM1 links the mevalonate pathway to oncogenic signals in HCC. Thus, we propose a novel therapeutic approach to inhibit FoxM1 by targeting the mevalonate pathway for HCC.

Antitumor activity of pamidronate in breast cancer cells transformed by low doses of α-particles and estrogen in vitro

Human breast cancer is a major cause of global morbidity and mortality in women and it is a process that involves numerous molecular and cellular alterations attributed to environmental substances and agents such as hormones. Bisphosphonates, such as pamidronate, are potent antiresorptive drugs used to the treatment of metabolic bone disease, exerting anti-proliferative, anti-migratory and apoptotic effects. The aim of this study was to evaluate gene and protein expression involved in these processes. An in vitro model was developed with the MCF-10F immortalized breast epithelial cell line exposed to low radiation doses of high LET (linear energy transfer) α-particles (150 keV/µm) and cultured in the presence of 17β-estradiol (estrogen). This model consisted of the following cell lines: i) MCF-10F, normal; ii) Alpha3, non-malignant; iii) Alpha5, pre-tumorigenic, and iv) Tumor2, derived from Alpha5 injected into the nude mice. Our previous results have shown that Alpha5 and Tumor2 increased cell proliferation, anchorage independency, invasive capabilities and tumor formation in nude mice in comparison to control. Expression of the gene (RT-qPCR) and protein (western blotting, flow cyto-metry) was measured. The results indicated that pamidronate decreased invasion, migration and Rho-A, c-Ha-ras, p53, Serpin-1, Caveolin-1, Bcl-xL and NFκB gene and protein expression. Thus, it seems that pamidronate may impinge upon cellular proliferation, invasion, metastasis and apoptosis and it may exert antitumor activity in breast cancer cells transformed by low doses of α-particles and estrogen in vitro.

Bisphosphonate prodrugs: synthesis and biological evaluation in HuH7 hepatocarcinoma cells

We investigated the biological effects of new synthesized bisphosphonates (BPs) on HuH7 hepatocarcinoma cells. BPs containing p-bromophenyl (R1 = p-Br, Ph, 2) in their side chain were the more potent to inhibit HuH7 cell viability. In addition, phenyl diesterified analogues (R2 = R3 = Ph, 2a) were more potent than methyl (R2 = R3 = Me, 2b) or non-esterified BPs (2) inducing more necrosis suggesting that they better entered into cells. Phosphodiesterase inhibitor (IBMX) reversed the effect of the esterified BPs and not that of non-esterified ones suggesting role of cell phosphodiesterases to release active BPs. BP analogues inhibited HuH7 cell migration but esterified ones had no effect on invasion due to the hiding of phosphonic groups. All together, these results indicated the therapeutic interest of these new BP prodrugs.

Anticancer activity of Zea mays leaf extracts on oxidative stress-induced Hep2 cells

Cancer is one of the leading causes of death in humans. It is believed that plants can provide potential bioactive compounds for the development of "new leads" to combat cancer and other diseases. The present study focuses on the ability of the different extracts (aqueous, methanol, and chloroform) of the leaves of Zea mays in influencing the process of apoptosis induced by hydrogen peroxide (H2O2) in Hep2 (laryngeal carcinoma) cells. Various apoptosis-related parameters, such as cell viability, morphological changes, nuclear changes, and apoptotic index were characterized. sulforhodamine B and MTT assays were used to quantify the extent of cell death in the group exposed to H2O2, plant extracts, and their combination. Treatment with H2O2 caused cytotoxicity in cancer cells. The administration of leaf extract also caused an increase in the death of cancer cells. Oxidatively stressed cancer cells co-treated with all the Z. mays leaf extracts (except the chloroform extract) demonstrated cytotoxicity on a par with the H2O2-treated groups. This indicated that the aqueous and methanol leaf extracts did not influence the cytotoxic action of H2O2 in the cancer cells. Thus, various apoptosis-related events in Hep2 cells exposed to leaf extract throw light on the potential anticancer activity of the Z. mays leaves. The maximum activity was exerted by the methanolic extract followed by the aqueous and chloroform extracts.

The role of Raf kinase inhibitor protein in rheumatoid fibroblast-like synoviocytes invasiveness and cytokine and matrix metalloproteinase expression

Fibroblast-like synoviocytes (FLS) play an important role in the pathogenesis of rheumatoid arthritis. Raf kinase inhibitor protein (RKIP) negatively regulates the Raf/MEK/ERK and NF-κB pathway. The role of RKIP in rheumatoid FLS is unknown. The purpose of the present study was to investigate the function of RKIP in rheumatoid FLS. Rheumatoid FLS were transfected with either RKIP-expressing plasmids or RKIP small interfering RNA (siRNA). RKIP protein was detected in rheumatoid synovial tissue (ST) and FLS. RKIP overexpression significantly decreased IL-6 mRNA expression in TNF-α-stimulated rheumatoid FLS. RKIP overexpression also showed a decreased trend in IL-8, MMP-1, and MMP-3 mRNA expression in TNF-α-stimulated rheumatoid FLS. RKIP silencing resulted in significantly increased MMP-1 and MMP-3 mRNA expression in TNF-α-stimulated rheumatoid FLS. RKIP silencing also increased IL-6 and IL-8 mRNA expression in TNF-α-stimulated rheumatoid FLS, but this increase did not reach statistical significance. TNF-α-induced ERK and NF-κB activation was suppressed in FLS with RKIP overexpression. RKIP silencing resulted in a significantly higher invasion index in TNF-α-stimulated rheumatoid FLS compared to controls. These results suggest that RKIP might be a potential therapeutic target for rheumatoid arthritis.

Chrysophanol induces necrosis through the production of ROS and alteration of ATP levels in J5 human liver cancer cells

Anthraquinone compounds have been shown to induce apoptosis in different cancer cell types. Effects of chrysophanol, an anthraquinone compound, on cancer cell death have not been well studied. The goal of this study was to examine if chrysophanol had cytotoxic effects and if such effects involved apoptosis or necrosis in J5 human liver cancer cells. Chrysophanol induced necrosis in J5 cells in a dose- and time-dependent manner. Non-apoptotic cell death was induced by chrysophanol in J5 cells and was characterized by caspase independence, delayed externalization of phosphatidylserine and plasma membrane disruption. Blockage of apoptotic induction by a general caspase inhibitor (z-VAD-fmk) failed to protect cells against chrysophanol-induced cell death. The levels of reactive oxygen species production and loss of mitochondrial membrane potential (DeltaPsi(m)) were also determined to assess the effects of chrysophanol. However, reductions in adenosine triphosphate levels and increases in lactate dehydrogenase activity indicated that chrysophanol stimulated necrotic cell death. In summary, human liver cancer cells treated with chrysophanol exhibited a cellular pattern associated with necrosis and not apoptosis.

Aminobisphosphonate-pretreated dendritic cells trigger successful Vgamma9Vdelta2 T cell amplification for immunotherapy in advanced cancer patients

Hepatocellular carcinoma (HCC) and colorectal carcinoma with hepatic metastases (mCRC) are cancers with poor prognosis and limited therapeutic options. New approaches are needed and adoptive immunotherapy with Vgamma9Vdelta2 T lymphocytes represents an attractive strategy. Indeed, Vgamma9Vdelta2 T cells were shown to exhibit efficient lytic activity against various human tumor cell lines, and in vitro Vgamma9Vdelta2 T expansion protocol based on single phosphoantigen stimulation could be easily performed for healthy donors. However, a low proliferative response of Vgamma9Vdelta2 T cells was observed in about half of the cancer patients, leading to an important limitation in the development of Vgamma9Vdelta2 T cell-based immunotherapy. Here, for the first time in the context of cancer patients, Vgamma9Vdelta2 T cell expansions were performed by co-culturing peripheral blood mononuclear cell (PBMCs) with autologous dendritic cells (DCs) pretreated with aminobisphosphonate zoledronate. For patients not responding to the conventional culture protocol, co-culture of PBMC with zoledronate-pretreated DCs induced strong cell expansion and allowed reaching a minimal rate of purity of 70% of Vgamma9Vdelta2 T cells. The potent immunostimulatory activity of zoledronate-treated DCs was associated with higher amount of isopentenyl pyrophosphate (IPP) in the culture and was correlated with better ability to activate Vgamma9Vdelta2 T cells as measured by IFN-gamma production. Moreover, we demonstrated that the cytotoxic level of Vgamma9Vdelta2 T cells against freshly autologous tumor cells isolated from patients could be significantly increased by pretreating the tumor cells with zoledronate. Thus, this method of generating Vgamma9Vdelta2 T cells leads eligible for Vgamma9Vdelta2 T cell adoptive immunotherapy the HCC and mCRC patients.

Nitrogen-containing bisphosphonate, YM529/ONO-5920, inhibits tumor metastasis in mouse melanoma through suppression of the Rho/ROCK pathway

The small GTPases of the Ras and Rho families are widely involved in tumorigenesis and metastasis. We recently showed that YM529/ONO-5920, a new developed bisphosphonate, inhibits the mevalonate pathway, is required for the prenylation of the small GTPases. In this study, we investigated whether YM529/ONO-5920 inhibits tumor cell migration, invasion, adhesion, and metastasis in B16BL6 cells, a mouse melanoma cell line. It was found that YM529/ONO-5920 significantly inhibited lung metastasis, cell migration, invasion, and adhesion at concentrations that did not show anti-proliferative effects on B16BL6 cells. YM529/ONO-5920 also inhibited the expression of matrix metalloproteinases (MMPs) and very late antigens (VLAs). Furthermore, YM529/ONO-5920 suppressed Rho activation, but not activation of Ras. The results indicate that YM529/ONO-5920 suppresses the Rho/ROCK pathways, thereby inhibiting B16BL6 cell migration, invasion, adhesion and metastasis. These findings suggest that YM529/ONO-5920 has potential clinical applications for the treatment of tumour cell metastasis.

Targeted therapy for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide. The major etiologies and risk factors for development of HCC are well defined and some steps of hepatocellular carcinogenesis have been elucidated. Despite these scientific advances and the implementation of measures for early detection of HCC in patients who are at risk of this disease, survival of patients has not improved greatly over the past three decades. This situation is partly due to the limited therapeutic options available. While surgery and percutaneous or transarterial interventions are effective for patients with limited or compensated underlying liver disease, more than 80% of patients present with multifocal HCC and/or advanced liver disease, or have comorbidities at the time of diagnosis. Treatment options for these patients have previously been limited to best supportive care. The effectiveness of targeted therapy with monoclonal antibodies or small-molecule kinase inhibitors has now been demonstrated for the treatment of different tumors. In 2007, the multitargeted kinase inhibitor, sorafenib, was found to prolong survival significantly for patients with advanced HCC. This Review discusses the mechanisms of targeted therapies and clinical studies that have investigated these therapies in patients with HCC. Perspectives for future developments are also provided.

A novel third generation bisphosphonate, minodronate (YM529), prevented proliferation and migration of hepatocellular carcinoma cells through inhibition of mevalonate pathway

AIM

Skeletal metastases and bone metasitasis are a common occurrence in patients with advanced hepatocellular carcinoma (HCC). Bisphosphonates (BPs), which are used for the treatment of osteoporosis and tumor-associated hypercalcemia, have recently been reported to decrease skeletal morbidity in patients with metastatic bone disease. Several studies revealed that nitrogen-containing BPs (N-BPs) could inhibit tumor growth and migration, indicating the possibility that N-BPs have direct inhibitory effects. We aimed to determine the effects of novel a N-BP (YM529) on human HCC cells in vitro.

METHODS

HCC cells were treated with various concentrations of YM529 and the growth inhibition rate was determined. Apoptosis was evaluated by caspase-3/7 assay and caspase-9 cleavage detection. The effects of YM529 on the migration of HCC cells induced by hepatocyte growth factor (HGF) were determined by cell migration assay. To evaluate the involvement of the mevalonate pathway, farnesol (FOH) and geranylgeraniol (GGOH) were added.

RESULTS

YM529 inhibited the proliferation of HCC cells in a dose-dependent manner. The activation of caspase-3/7 and cleavage of caspase-9 demonstrated the involvement of apoptosis in cytotoxicity. GGOH reduced the growth inhibitory effect of YM529 and suppressed the induction of caspase-3/7 activities by YM529 on HCC cells. YM529 inhibited tumor cell migration induced by HGF and this effect was reduced by co-treatment with GGOH.

CONCLUSION

YM529 inhibited the cell proliferation and migration of HCC cells, implicating the involvement of the mevalonate pathway. These results suggest that N-BPs are potential agents for the treatment of HCC skeletal metastases.

Rho GTPases in hepatocellular carcinoma

Rho GTPases are major regulators of signal transduction pathways and play key roles in processes including actin dynamics, cell cycle progression, cell survival and gene expression, whose deregulation may lead to tumorigenesis. A growing number of in vitro and in vivo studies using tumor-derived cell lines, primary tumors and animal cancer models strongly suggest that altered Rho GTPase signaling plays an important role in the initiation as well as in the progression of hepatocellular carcinoma (HCC), one of the deadliest human cancers in the world. These alterations can occur at the level of the GTPases themselves or of one of their regulators or effectors. The participation into the tumorigenic process can occur either through the over-expression of one of these components which presents an oncogenic activity as illustrated with RhoA and C or through the attenuation of the expression of a component presenting tumor suppressor activity as for Cdc42 or the RhoGAP, DLC-1. Consequently, these observations reflect the heterogeneity and the complexity of liver carcinogenesis. Recently, pharmacological approaches targeting Rho GTPase signaling have been used in HCC-derived models with relative success but remain to be validated in more physiologically relevant systems. Therefore, therapeutic approaches targeting Rho GTPase signaling may provide a novel alternative for anti-HCC therapy.

Bisphosphonates in cancer therapy

Bisphosphonates are the standard of care in the treatment of malignant bone diseases, because of their ability to inhibit osteoclast-mediated bone destruction. We review here preclinical evidence that bisphosphonates also exert direct antitumour effects and antiangiogenic properties. Furthermore, we describe new insights on how bisphosphonates may act synergistically in combination with antineoplastic drugs or gammadelta T cells to exhibit antitumour activity. These findings reveal new exciting possibilities to fully exploit the antitumour potential of bisphosphonates in the clinical practice.

Mevalonate pathway: a review of clinical and therapeutical implications

Mevalonate pathway is an important metabolic pathway which plays a key role in multiple cellular processes by synthesizing sterol isoprenoids, such as cholesterol, and non-sterol isoprenoids, such as dolichol, heme-A, isopentenyl tRNA and ubiquinone. While extensively studied in regard with cholesterol synthesis and its implications in cardiovascular diseases, in recent years the mevalonate pathway has become a challenging and, in the meantime, fascinating topic, when a large number of experimental and clinical studies suggested that inhibition of non-sterol isoprenoids might have valuable interest in human pathology. These molecules that are essential for cell growth and differentiation appear to be potential interesting therapeutic targets for many areas of ongoing research: oncology, autoimmune disorders, atherosclerosis, and Alzheimer disease. Also, considerable progress has been made in the past decade in understanding the pathophysiology of two auto-inflammatory disorders resulting from an inherited deficiency of mevalonate kinase, the first committed enzyme of the mevalonate pathway. Here we present a brief description of the biochemistry of the mevalonate pathway, together with a review of the current knowledge of the clinical and therapeutical implications of this fascinating and complex metabolic pathway.

Loss of Raf kinase inhibitor protein promotes cell proliferation and migration of human hepatoma cells

BACKGROUND & AIMS

The Raf kinase inhibitor protein (RKIP) has been identified as a suppressor of the mitogen-activated protein kinase (MAPK) pathway. Loss of RKIP function promotes tumor metastasis in prostate cancer and melanoma. The insulin-like growth factor I (IGF-I)-mediated MAPK cascade is often activated in hepatocellular carcinoma (HCC), but the role of RKIP in the molecular pathogenesis of these tumors is unknown. This study was performed to evaluate the role of RKIP in the development of HCC.

METHODS

The levels of RKIP expression in HCC tumor and corresponding peritumoral tissues were determined by immunohistochemistry and Western blot analysis. The underlying mechanisms of RKIP were assessed with immunoblot analysis, Raf kinase activity assay, cell proliferation, and migration assays after either overexpression or knockdown of RKIP expression in HCC cell lines.

RESULTS

RKIP expression is down-regulated in human HCC compared with adjacent peritumoral tissues. Low RKIP levels were correlated with enhanced extracellular signal-regulated-kinase (ERK)/MAPK pathway activation. Reconstitution experiments antagonized IGF-I-mediated MAPK pathway activation, resulting in reduced nuclear accumulation of phospho-ERK. In contrast, knockdown of RKIP expression using small interfering RNA induced activation of the ERK/MAPK pathway. Ectopic expression of RKIP altered HCC cell proliferation and migration.

CONCLUSIONS

Our findings indicate that down-regulation of RKIP expression is a major factor in activation of the IGF-I/ERK/MAPK pathway during human hepatocarcinogenesis.