Ras pathway activation in hepatocellular carcinoma and anti-tumoral effect of combined sorafenib and rapamycin in vivo

Temsirolimus combined with sorafenib in hepatocellular carcinoma: a phase I dose-finding trial with pharmacokinetic and biomarker correlates

BACKGROUND

Based upon preclinical evidence for improved antitumor activity in combination, this phase I study investigated the maximum-tolerated dose (MTD), safety, activity, pharmacokinetics (PK), and biomarkers of the mammalian target of rapamycin inhibitor, temsirolimus, combined with sorafenib in hepatocellular carcinoma (HCC).

PATIENTS AND METHODS

Patients with incurable HCC and Child Pugh score ≤B7 were treated with sorafenib plus temsirolimus by 3 + 3 design. The dose-limiting toxicity (DLT) interval was 28 days. The response was assessed every two cycles. PK of temsirolimus was measured in a cohort at MTD.

RESULTS

Twenty-five patients were enrolled. The MTD was temsirolimus 10 mg weekly plus sorafenib 200 mg twice daily. Among 18 patients at MTD, DLT included grade 3 hand-foot skin reaction (HFSR) and grade 3 thrombocytopenia. Grade 3 or 4 related adverse events at MTD included hypophosphatemia (33%), infection (22%), thrombocytopenia (17%), HFSR (11%), and fatigue (11%). With sorafenib, temsirolimus clearance was more rapid (P < 0.05). Two patients (8%) had a confirmed partial response (PR); 15 (60%) had stable disease (SD). Alpha-fetoprotein (AFP) declined ≥50% in 60% assessable patients.

CONCLUSION

The MTD of sorafenib plus temsirolimus in HCC was lower than in other tumor types. HCC-specific phase I studies are necessary. The observed efficacy warrants further study.

Obesity-induced gut microbial metabolite promotes liver cancer through senescence secretome

Obesity has become more prevalent in most developed countries over the past few decades, and is increasingly recognized as a major risk factor for several common types of cancer. As the worldwide obesity epidemic has shown no signs of abating, better understanding of the mechanisms underlying obesity-associated cancer is urgently needed. Although several events were proposed to be involved in obesity-associated cancer, the exact molecular mechanisms that integrate these events have remained largely unclear. Here we show that senescence-associated secretory phenotype (SASP) has crucial roles in promoting obesity-associated hepatocellular carcinoma (HCC) development in mice. Dietary or genetic obesity induces alterations of gut microbiota, thereby increasing the levels of deoxycholic acid (DCA), a gut bacterial metabolite known to cause DNA damage. The enterohepatic circulation of DCA provokes SASP phenotype in hepatic stellate cells (HSCs), which in turn secretes various inflammatory and tumour-promoting factors in the liver, thus facilitating HCC development in mice after exposure to chemical carcinogen. Notably, blocking DCA production or reducing gut bacteria efficiently prevents HCC development in obese mice. Similar results were also observed in mice lacking an SASP inducer or depleted of senescent HSCs, indicating that the DCA-SASP axis in HSCs has key roles in obesity-associated HCC development. Moreover, signs of SASP were also observed in the HSCs in the area of HCC arising in patients with non-alcoholic steatohepatitis, indicating that a similar pathway may contribute to at least certain aspects of obesity-associated HCC development in humans as well. These findings provide valuable new insights into the development of obesity-associated cancer and open up new possibilities for its control.

Actionable gene expression-based patient stratification for molecular targeted therapy in hepatocellular carcinoma

Background

The effectiveness of molecular targeted agents is modest in hepatocellular carcinoma (HCC). Efficacy of molecular targeted therapies has been better in cancer patients with high expression of actionable molecules defined as cognate target molecules. However, patient stratification based on the actionable molecules dictating the effectiveness of targeted drugs has remained understudied in HCC.

Experimental Design & Results

Paired tumor and non-tumoral tissues derived from a total of 130 HCC patients were studied. Real-time RT-PCR was used to analyze the mRNA expression of actionable molecules in the tissues. mRNA levels of EGFR, VEGFR2, PDGFRβ, FGFR1, and mTOR were up-regulated in tumors compared to non-tumors in 35.4, 42.3, 61.5, 24.6, and 50.0% of patients, respectively. Up-regulation of EGFR was observed at early stage and tended to gradually decrease toward late stages (BCLC stage A: 41.9%; B: 30.8%; C: 17.6%). Frequency of VEGFR2 expression in tumors at stage C was lower than that in the other stages (BCLC stage A: 45.9%; B: 41.0%; C: 29.4%). PDGFRβ and mTOR were observed to be up-regulated in more than 50% of tumors in all the stages whereas FGFR1 was up-regulated in only about 20% of HCC irrespective of stages. A cluster analysis of actionable gene expression revealed that HCC can be categorized into different subtypes that predict the effectiveness of molecular targeted agents and combination therapies in clinical trials. Analysis of in vitro sensitivity to sorafenib demonstrated that HCC cells with up-regulation of PDGFRβ and c-Raf mRNA are more susceptible to sorafenib treatment in a dose and time-dependent manner than cells with low expression of the genes.

Conclusions

mRNA expression analysis of actionable molecules could provide the rationale for new companion diagnostics-based therapeutic strategies in the treatment of HCC.

Sorafenib treatment for recurrent hepatocellular carcinoma after liver transplantation

BACKGROUND

With an increasing number of patients with hepatocellular carcinoma (HCC) undergoing liver transplantation (OLT), HCC recurrence remains the main limiting factor for long-term survival. We herein report our experience with sorafenib treatment for HCC recurrence post-OLT.

PATIENTS AND METHODS

We reviewed data on transplanted HCC patients receiving sorafenib for HCC recurrence.

RESULTS

Fourteen patients were included for the period November 2006 to February 2011. There were 9 men and 5 women of median age of 57 years. Twelve patients (86%) received rescue grafts through Eurotransplant allocation. Median values for alpha fetoprotein levels, Model for End-Stage Liver Disease score, sorafenib daily dose, and length of treatment were 97 ng/mL, 10, 400 mg, and 6.5 months, respectively. Sorafenib side effects led to discontinuation (n = 4) or reduction (n = 2) of the daily dose. Four patients experienced tumor progression during treatment. Seven patients are currently alive, 3 patients died of tumor progression, and 4 patients of non-tumor-related causes of death. Median survival was 25 months.

CONCLUSION

Sorafenib treatment for HCC recurrence in transplant recipients represents a challenging oncologic approach that requires further validation in prospective, multicenter studies.

Functional crosstalk between AKT/mTOR and Ras/MAPK pathways in hepatocarcinogenesis: implications for the treatment of human liver cancer

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death worldwide, with limited treatment options. AKT/mTOR and Ras/MAPK pathways are frequently deregulated in human hepatocarcinogenesis. Recently, we generated an animal model characterized by the co-expression of activated forms of AKT and Ras in the mouse liver. We found that concomitant activation of AKT/mTOR and Ras/MAPK cascades leads to rapid liver tumor development in AKT/Ras mice, mainly through mTORC1 induction. To further define the role of mTORC1 cascade in AKT/Ras induced HCC development, the mTORC1 inhibitor Rapamycin was administered to AKT/Ras mice at the time when small tumors started to emerge in the liver. Of note, Rapamycin treatment significantly delayed hepatocarcinogenesis in AKT/Ras mice. However, some microscopic lesions persisted in the livers of AKT/Ras mice despite the treatment and rapidly gave rise to HCC following Rapamycin withdrawal. Mechanistically, Rapamycin inhibited mTORC1 and mTORC2 pathways, lipogenesis and glycolysis, resulting in inhibition of proliferation in the treated livers. However, activated ERK and its downstream effectors, Mnk1 and eIF4E, were strongly upregulated in the residual lesions. Concomitant suppression of AKT/mTOR and Ras/MAPK pathways was highly detrimental for the growth of AKT/Ras cells in vitro. The study indicates the existence of a complex interplay between AKT/mTOR and Ras/MAPK pathways during hepatocarcinogenesis, with important implications for the understanding of HCC pathogenesis as well as for its prevention and treatment.

Activity of the mTOR inhibitor RAD001, the dual mTOR and PI3-kinase inhibitor BEZ235 and the PI3-kinase inhibitor BKM120 in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most deadly cancers worldwide with only few therapeutic options for patients with advanced disease. There is growing evidence indicating that activation of the PI3K/Akt/mTOR pathway plays an important role in HCC and therefore represents a promising target for novel therapeutic approaches. The aim of this study was to evaluate and compare the antitumour activity of the mTOR inhibitor RAD001, the dual mTOR and PI3-kinase inhibitor BEZ235 and the PI3-kinase inhibitor BKM120 in vitro and in vivo.

EXPERIMENTAL DESIGN

The antitumour effects of RAD001, BEZ235 and BKM120 were analysed in seven hepatoma cell lines as mono and combination therapy with Doxorubicin, Cisplatin, Irinotecan or 5-Flourouracil in vitro and in xenografts. Cell-cycle progression, apoptosis, and autophagy were analysed. Furthermore, effects on mitochondrial respiration and glycolysis were assessed.

RESULTS

Treatment with RAD001, BEZ235 and BKM120 markedly reduced tumour cell viability. Combination of PI3K inhibitors with chemotherapy was most effective. RAD001, BEZ235 and BKM120 reduced tumour growth mainly by inhibiting cell-cycle progression rather than by inducing apoptosis. Interestingly, the antitumour effects were strongly associated with a reduction of mitochondrial respiration. BKM120, which exhibited the strongest antiproliferative effect, most strongly impaired oxidative phosphorylation compared with the other drugs.

CONCLUSIONS

In this study, BKM120 showed the strongest antitumour activity. Our findings suggest impairment of mitochondrial function as a relevant mechanism of BKM120. Moreover, combination of PI3K and mTOR inhibitors with cytotoxic agents could be promising option for non-cirrhotic HCC patients.

Tumor-initiating stem-like cells and drug resistance: carcinogenesis through Toll-like receptors, environmental factors, and virus

Neoplasms contain distinct subpopulations of cells known as tumor-initiating stem-like cells (TICs) that have been identified as key drivers of tumor growth and malignant progression with drug resistance. Stem cells normally proliferate through self-renewing divisions in which the two daughter cells differ markedly in their proliferative potential, with one displaying the differentiation phenotypes and another retaining self-renewing activity. Therefore, understanding the molecular mechanisms of hepatocarcinogenesis will be required for the eventual development of improved therapeutic modalities for treating hepatocellular carcinoma (HCC). Hepatitis C virus (HCV) and hepatitis B virus is a major cause of HCC. Compelling epidemiologic evidence identifies obesity and alcohol as co-morbidity factors that can increase the risk of HCV patients for HCC, especially in alcoholics or obese patients. The mechanisms underlying liver oncogenesis, and how environmental factors contribute to this process, are not yet understood. The HCV-Toll-like receptor 4 (TLR4)-Nanog signaling network is established since alcohol/obesity-associated endotoxemia then activates TLR4 signaling, resulting in the induction of the stem cell marker Nanog expression and liver tumors. Liver TICs are highly sensitized to leptin and exposure of TICs to leptin increases the expression and activity of an intrinsic pluripotency-associated transcriptional network comprised of signal transducer and activator of transcription 3, SOX2, OCT4, and Nanog. Stimulation of the pluripotency network may have significant implications for hepatocellular oncogenesis via genesis and maintenance of TICs. It is important to understand how HCV induces liver cancer through genesis of TICs so that better prevention and treatment can be found. This article reviews the oncogenic pathways to generate TICs.

Investigation of oncogenic cooperation in simple liver-specific transgenic mouse models using noninvasive in vivo imaging

Liver cancer is a complex multistep process requiring genetic alterations in multiple proto-oncogenes and tumor suppressor genes. Although hundreds of genes are known to play roles in hepatocarcinogenesis, oncogenic collaboration among these genes is still largely unknown. Here, we report a simple methodology by which oncogenic cooperation between cancer-related genes can be efficiently investigated in the liver. We developed various non-germline transgenic mouse models using hydrodynamics-based transfection which express HrasG12V, SmoM2, and a short-hairpin RNA down-regulating p53 (shp53) individually or in combination in the liver. In this transgenic system, firefly luciferase was co-expressed with the oncogenes as a reporter, allowing tumor growth in the liver to be monitored over time without an invasive procedure. Very strong bioluminescence imaging (BLI) signals were observed at 4 weeks post-hydrodynamic injection (PHI) in mice co-expressing HrasG12V and shp53, while only background signals were detected in other double or single transgenic groups until 30 weeks PHI. Consistent with the BLI data, tumors were observed in the HrasG12V plus shp53 group at 4 weeks PHI, while other transgenic groups failed to exhibit a hyperplastic nodule at 30 weeks PHI. In the HrasG12V plus shp53 transgenic group, BLI signals were well-correlated with actual tumor growth in the liver, confirming the versatility of BLI-based monitoring of tumor growth in this organ. The methodology described here is expected to accelerate and facilitate in vivo studies of the hepatocarcinogenic potential of cancer-related genes by means of oncogenic cooperation.

Deregulation of signalling pathways in prognostic subtypes of hepatocellular carcinoma: novel insights from interspecies comparison

Hepatocellular carcinoma is a frequent and fatal disease. Recent researches on rodent models and human hepatocarcinogenesis contributed to unravel the molecular mechanisms of hepatocellular carcinoma dedifferentiation and progression, and allowed the discovery of several alterations underlying the deregulation of cell cycle and signalling pathways. This review provides an interpretive analysis of the results of these studies. Mounting evidence emphasises the role of up-regulation of RAS/ERK, P13K/AKT, IKK/NF-kB, WNT, TGF-ß, NOTCH, Hedgehog, and Hippo signalling pathways as well as of aberrant proteasomal activity in hepatocarcinogenesis. Signalling deregulation often occurs in preneoplastic stages of rodent and human hepatocarcinogenesis and progressively increases in carcinomas, being most pronounced in more aggressive tumours. Numerous changes in signalling cascades are involved in the deregulation of carbohydrate, lipid, and methionine metabolism, which play a role in the maintenance of the transformed phenotype. Recent studies on the role of microRNAs in signalling deregulation, and on the interplay between signalling pathways led to crucial achievements in the knowledge of the network of signalling cascades, essential for the development of adjuvant therapies of liver cancer. Furthermore, the analysis of the mechanisms involved in signalling deregulation allowed the identification of numerous putative prognostic markers and novel therapeutic targets of specific hepatocellular carcinoma subtypes associated with different biologic and clinical features. This is of prime importance for the selection of patient subgroups that are most likely to obtain clinical benefit and, hence, for successful development of targeted therapies for liver cancer.

Neuroglobin, a novel intracellular hexa-coordinated globin, functions as a tumor suppressor in hepatocellular carcinoma via Raf/MAPK/Erk

Hypoxia and oxidative stress are critical factors in carcinogenesis and exist throughout cancer development; however, the underlying mechanisms are far from clear. Here, for the first time to our knowledge, we reported that neuroglobin (Ngb), an intracellular hexa-coordinated globin serving as an oxygen/reactive oxygen species (ROS) sensor, functions as a tumor suppressor in hepatocelluar carcinoma (HCC). Ngb protein and mRNA expression were significantly down-regulated in tumor tissues, compared with its adjacent non-tumor tissues of human HCC samples and normal liver tissues. Knock-down of Ngb by RNA interference promoted human HCC cell line (HepG2) growth and proliferation, G0/G1-S transition in vitro, and tumor growth in vivo. On the contrary, overexpression of Ngb suppressed HepG2 cell growth and proliferation, G0/G1-S transition, colony formation in vitro, and tumorigenicity in vivo. These results established a tumor suppressor function of Ngb in HCC. The underlying mechanisms were further investigated. Overexpression of Ngb suppressed Raf/MEK/extracellular signal-regulated kinase (Erk), whereas knockdown of Ngb enhanced Raf/MEK/Erk activation in HepG2 cells in vitro and in vivo. Glutathione S-transferase pull-down showed that Ngb interacted with c-Raf-1 in HepG2 cells. Overexpression of Ngb suppressed serum- and H₂O₂-stimulated Erk activation in HepG2 cells. Pharmacological inhibition of Erk activation abolished the proliferative effect of Ngb knockdown in HepG2 cells. Mutation of Ngb at its oxygen-binding site (H64L) abolished the inhibitory effects of Ngb on Erk activation and HepG2 cell proliferation. Therefore, we propose that Ngb controls HCC development by linking oxygen/ROS signals to oncogenic Raf/mitogen-activated protein kinase (MAPK)/Erk signaling. Our data suggest that neuroglobin could be a new target for cancer therapy.

Synergistic interactions between sorafenib and everolimus in pancreatic cancer xenografts in mice

PURPOSE

Molecular targeting of cellular signaling pathways is a promising approach in cancer therapy, but often fails to achieve sustained benefit because of the activation of collateral cancer cell survival and proliferation pathways. We tested the hypothesis that a combination of targeted agents that inhibit compensatory pathways would be more effective than single agents in controlling pancreatic cancer cell growth. We investigated whether everolimus, an mTOR inhibitor, and sorafenib, a multi-kinase inhibitor, would together inhibit growth of low-passage, patient-derived pancreatic cancer xenografts in mice more efficaciously than either agent alone.

METHODS

Tumor volume progression was measured following treatment with both drugs as single agents, in combination, and at multiple doses. Pharmacokinetics in tumors and other tissues was also assessed. Pharmacodynamic interactions were evaluated quantitatively.

RESULTS

A 5-week regimen of daily oral doses of 10 mg/kg sorafenib and 0.5 mg/kg everolimus, alone and in combination, did not achieve significant tumor growth inhibition. Higher doses (20 mg/kg of sorafenib and 1 mg/kg of everolimus) inhibited tumor growth significantly when given alone and caused complete inhibition of growth when given in combination. Tumor volume progression was described by a linear growth model, and drug effects were described by Hill-type inhibition. Using population modeling approaches, dual-interaction parameter estimates indicated a highly synergistic pharmacodynamic interaction between the two drugs.

CONCLUSIONS

The results indicate that combinations of mTOR and multi-kinase inhibitors may offer greater efficacy in pancreatic cancer than either drug alone. Drug effects upon tumor stromal elements may contribute to the enhanced anti-tumor efficacy.

Adverse events affect sorafenib efficacy in patients with recurrent hepatocellular carcinoma after liver transplantation: experience at a single center and review of the literature

AIMS

The aim of this study was to assess the safety and efficacy of sorafenib, with or without everolimus, in the treatment of recurrent hepatocellular carcinoma (HCC) after an orthotopic liver transplantation (OLT).

METHODS

We reviewed the outcome of our consecutive cohort series of patients. Eleven patients (nine men) with recurrent HCC after OLT were treated. Four patients received cyclosporine plus sorafenib at a starting dose of 400 mg twice daily; seven received the combination of sorafenib (same dosage) and everolimus. Sorafenib was reduced or stopped according to the drug label.

RESULTS

The median time to recurrence was 12 months (range 2-66). The mean age at the start of treatment was 57 ± 9 years. Sorafenib was withdrawn because of intolerance or side-effects in four (36%) patients. Dose reduction because of adverse events or intolerance was required in 91% of patients after 26 ± 11 days from the start of treatment. The average length of treatment was 68 days (range 15-444). One patient died because of a massive gastrointestinal bleeding while receiving sorafenib and everolimus. The most frequent adverse events were fatigue (54%), skin toxicity (45%), and hypophosphatemia (36%). Two patients (18%) showed a radiological partial response, one (9%) had a stable disease, and six (54%) showed a progressive disease. None of the patients achieved a complete response. Treatment response could not be assessed in two (18%) patients. The overall median survival since the start of treatment was 5 months. One-year survival was 18%.

CONCLUSION

Sorafenib, with or without mammalian target of rapamycin inhibitors, is poorly tolerated and rarely effective in the treatment of recurrent HCC after OLT.

Current and Future Treatment Strategies for Patients with Advanced Hepatocellular Carcinoma: Role of mTOR Inhibition

Hepatocellular carcinoma (HCC) is a common cancer that has the third highest cancer-related mortality rate worldwide. Although potentially curable by transplantation if detected early, the majority of cases are diagnosed at an advanced stage of disease for which limited treatment options are available. The only proven systemic therapy for advanced HCC is sorafenib, a multi-kinase inhibitor that has demonstrated modest efficacy and reasonable tolerability in patients with advanced HCC. Five years after the approval of sorafenib, no other agent has been proven to be beneficial in the first- or second-line setting in advanced HCC. While molecular studies have highlighted various potential targets in HCC, the mammalian target of rapamycin (mTOR) has emerged as an exciting target for cancer therapy including HCC. Laboratory data have linked the phosphatidylinositol 3-kinase/AKT/mTOR axis to various oncogenic processes, including survival and angiogenesis. Historically, mTOR inhibitors have been used for their immunosuppressive properties, but more recently they have been approved as anticancer agents. Retrospective HCC studies suggest that the inclusion of mTOR inhibition as part of an immunosuppressant regimen after transplantation may reduce HCC recurrence compared with other immunosuppressive agents such as calcineurin inhibitors. More recently, single-arm, phase I/II studies have shown that mTOR inhibitors also have activity as monotherapy in cases of recurrent HCC or de novo advanced HCC. This article will review the rationale for targeting the mTOR pathway in HCC, and the currently available clinical data supporting its development for HCC.

Interactions of everolimus and sorafenib in pancreatic cancer cells

Everolimus targets the mammalian target of rapamycin, a kinase that promotes cell growth and proliferation in pancreatic cancer. Sorafenib inhibits the Raf-mitogen-activated protein kinase, vascular endothelial growth factor, and platelet-derived growth factor pathways, thus inhibiting cell growth and angiogenesis. Combinations of these two agents are under evaluation for therapy of several cancers. This study examined the effects of everolimus and sorafenib on proliferation of the pancreatic cancer cell lines MiaPaCa-2 and Panc-1. Cell growth inhibition was evaluated in vitro for a range of concentrations of the drugs alone and in combination. Maximum inhibition capacity (I (max)) and potency (IC(50)) were determined. The data were analyzed to characterize drug interactions using two mathematical analysis techniques. The Ariens noncompetitive interaction model and Earp model were modified to accommodate alterations in the inhibition parameters of one drug in the presence of another. Sorafenib alone inhibited growth of both cell lines completely (I (max) = 1), with an IC(50) of 5-8 μM. Maximal inhibition by everolimus alone was only 40% (I (max) = 0.4) in both cell lines, with an IC(50) of 5 nM. Slight antagonistic interaction occurred between the drugs; both analytic methods estimated the interaction term Ψ as greater than 1 for both cell lines. The in vitro data for two pancreatic cancer cell lines suggest that a combination of these two drugs would be no more efficacious than the individual drugs alone, consistent with the drug interaction analysis that indicated slight antagonism for growth inhibition.

Hepatoma cells from mice deficient in glycine N-methyltransferase have increased RAS signaling and activation of liver kinase B1

BACKGROUND & AIMS

Patients with cirrhosis are at high risk for developing hepatocellular carcinoma (HCC), and their liver tissues have abnormal levels of S-adenosylmethionine (SAMe). Glycine N-methyltransferase (GNMT) catabolizes SAMe, but its expression is down-regulated in HCC cells. Mice that lack GNMT develop fibrosis and hepatomas and have alterations in signaling pathways involved in carcinogenesis. We investigated the role of GNMT in human HCC cell lines and in liver carcinogenesis in mice.

METHODS

We studied hepatoma cells from GNMT knockout mice and analyzed the roles of liver kinase B1 (LKB1, STK11) signaling via 5'-adenosine monophosphate-activated protein kinase (AMPK) and Ras in regulating proliferation and transformation.

RESULTS

Hepatoma cells from GNMT mice had defects in LKB1 signaling to AMPK, making them resistant to induction of apoptosis by adenosine 3',5'-cyclic monophosphate activation of protein kinase A and calcium/calmodulin-dependent protein kinase kinase 2. Ras-mediated hyperactivation of LKB1 promoted proliferation of GNMT-deficient hepatoma cells and required mitogen-activated protein kinase 2 (ERK) and ribosomal protein S6 kinase polypeptide 2 (p90RSK). Ras activation of LKB1 required expression of RAS guanyl releasing protein 3 (RASGRP3). Reduced levels of GNMT and phosphorylation of AMPKα at Thr172 and increased levels of Ras, LKB1, and RASGRP3 in HCC samples from patients were associated with shorter survival times.

CONCLUSIONS

Reduced expression of GNMT in mouse hepatoma cells and human HCC cells appears to increase activity of LKB1 and RAS; activation of RAS signaling to LKB1 and RASGRP3, via ERK and p90RSK, might be involved in liver carcinogenesis and be used as a prognostic marker. Reagents that disrupt this pathway might be developed to treat patients with HCC.

High toxicity of sorafenib for recurrent hepatocellular carcinoma after liver transplantation

Treatment options of recurrent hepatocellular carcinoma (HCC) after liver transplantation are limited and data on systemic compounds for advanced tumor stages in transplant recipients are sparse. We retrospectively analyzed the toxicity, tolerability, and efficacy of sorafenib in combination with mTOR inhibitors (mTORi), or calcineurin inhibitors (CNI) in transplant recipients with recurrent HCC. In total, 20 of 92 patients transplanted for HCC within a 10-year time period, experienced tumor recurrence. In case of ineligibility for other treatment options, patients received sorafenib (n = 13). In addition, CNI were stopped and switched to mTORi in nine patients, whereas CNI were continued in four patients. Grade 3-4 adverse events were observed in 92% of all patients necessitating sorafenib discontinuation in 77%. The most common severe adverse events were acute hepatitis, diarrhea, hand-foot - skin reaction and bone marrow suppression. In patients receiving sorafenib/mTORi one patient achieved partial response, and four achieved stable disease. In this cohort of liver transplant recipients side effects prevented full dosing of sorafenib and necessitated discontinuation of sorafenib in the majority of patients, yet antitumor efficacy seemed promising in combination with mTORi.

Sorafenib enhances the therapeutic efficacy of rapamycin in colorectal cancers harboring oncogenic KRAS and PIK3CA

Activation of phosphatidylinositol 3-kinase (PI3K)/Akt signaling is associated with tumorigenesis and metastasis of colorectal cancer (CRC). The mammalian target of rapamycin (mTOR) kinase, a downstream effector of PI3K/Akt signaling, regulates tumorigenesis and metastasis of CRCs, indicating that mTOR inhibition may have therapeutic potential. Notwithstanding, many cancers, including CRC, demonstrate resistance to the antitumorigenic effects of rapamycin. In this study, we show that inhibition of mTORC1 with rapamycin leads to feedback activation of PI3K/Akt and Ras-MAPK signaling, resulting in cell survival and possible contribution to rapamycin resistance. Combination with the multikinase inhibitor, sorafenib, abrogates rapamycin-induced activation of PI3K/Akt and Ras-MAPK signaling pathways. Combination of rapamycin with sorafenib synergistically inhibits proliferation of CRC cells. CRCs harboring coexistent KRAS and PIK3CA mutations are partially sensitive to either rapamycin or sorafenib monotherapy, but highly sensitive to combination treatment with rapamycin and sorafenib. Combination with sorafenib enhances therapeutic efficacy of rapamycin on induction of apoptosis and inhibition of cell-cycle progression, migration and invasion of CRCs. We demonstrate efficacy and safety of concomitant treatment with rapamycin and sorafenib at inhibiting growth of xenografts from CRC cells with coexistent mutations in KRAS and PIK3CA. The efficacy and tolerability of combined treatment with rapamycin and sorafenib provides rationale for use in treating CRC patients, particularly those with tumors harboring coexistent KRAS and PIK3CA mutations.

Valproate activates ERK signaling pathway in primary human hepatocytes

AIM

Valproic acid (VPA) is a widely-used anticonvulsant and mood-stabilizing agent. VPA is also known to inhibit histone deacetylases (HDACs) affecting the expression of numerous genes.

METHODS

In the present study, we examined the effect of VPA on the extracellular signal-related kinase (ERK, p42/p44) pathway (Ras-Raf-MEK-ERK) belonging to the mitogen-activated protein kinases (MAPKs) pathways in primary human hepatocytes. In the liver, the pathway is associated with progression of hepatocellular carcinoma.

RESULTS

We found that VPA in a therapeutically relevant concentration (500 µM) activates the ERK pathway, as indicated by increased ERK Thr202/Tyr204 phosphorylation. Interestingly, a prototype HDAC inhibitor, trichostatin A, also activated ERK phosphorylation in primary human hepatocytes. These data suggest that HDAC inhibition might be the primary stimulus for ERK pathway activation in primary human hepatocytes. Notably, U0126, a MEK1 inhibitor, was ineffective in inhibiting ERK pathway activation, likely due to its metabolic deactivation in metabolically competent primary human hepatocytes.

CONCLUSION

We conclude that VPA activates the ERK pathway in primary human hepatocytes.

Activation of JNK and high expression level of CD133 predict a poor response to sorafenib in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) ranks as the third leading cause of cancer deaths worldwide. While sorafenib, a multikinase inhibitor targeting the Raf/extracellular signal-regulated protein kinase (ERK) pathway, has been shown recently to provide a survival advantage to patients with advanced HCC, a predictive biomarker has not been developed. We studied whether c-Jun N-terminal kinase (JNK), which promotes liver carcinogenesis in mice, affects therapeutic response to sorafenib in HCC patients.

METHODS

We collected pathological specimens from 39 patients with advanced HCC before starting sorafenib treatment, and measured JNK activity in HCCs.

RESULTS

In patients treated with sorafenib, the expression of phospho-c-Jun in HCC, as a read out of JNK activity, was significantly higher (P<0.001) in the non-responder group than in the responder group. c-Jun N-terminal kinase activation in HCC was associated with a decreased time to progression and a poor overall survival (P=0.0028 and P=0.0008, respectively).

CONCLUSION

In addition, JNK activity was significantly correlated with CD133 expression level. Correspondingly, high expression level of CD133 was linked to a poor response to sorafenib. Furthermore, D-JNKi, a specific JNK inhibitor, reduced the growth of xenografted CD133(+) cells in athymic mice. In conclusion, JNK activation was positively correlated with CD133 expression level and inversely correlated with the therapeutic response to sorafenib, suggesting that JNK activity may be considered as a new predictive biomarker for response to sorafenib treatment.

Translational medicine in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a highly complex disease that is generally resistant to commonly used chemotherapy and radiotherapy. Consequently, there is an urgent need for the development of new treatment strategies for this devastating disease. In the past decade, tremendous progress has been achieved in the molecular stratification of HCCs for diagnosis, prognosis, and therapeutic decision-making. To date, the molecular classification of HCCs has been carried out through transcriptomic, genetic and epigenetic profiling of tumors. Such research has led to identification of several potential molecular targets in HCC, and subsequently, development of novel systemic agents for the treatment of HCC has begun in earnest. In this article, we review the current knowledge of the molecular pathogenesis of HCC and outline potential areas for application of this knowledge in a clinical setting. As a typical virus and inflammation-associated cancer, both host immune response and tumor microenvironment have crucial roles in HCC pathogenesis. In addition, we examine the potential of immunotherapy and strategies targeting various components of the tumor microenvironment, as well as novel molecular and cellular targets in HCC such as cancer stem cells.

Sorafenib for recurrence of hepatocellular carcinoma after liver transplantation

BACKGROUND

Recurrence of hepatocellular carcinoma after orthotopic liver transplantation not amenable to surgical approaches is associated with poor outcome.

AIMS

Retrospective evaluation of the safety and efficacy of sorafenib in patients with post-transplant hepatocellular carcinoma recurrence.

METHODS

Patients with post-transplant hepatocellular carcinoma recurrence were treated with sorafenib. Adverse events were assessed using National Cancer Institute Common Toxicity Criteria of AEs version 3.0, tumour response was evaluated according to Response Evaluation Criteria in Solid Tumours.

RESULTS

First-line therapy after recurrence was surgery (n=6), radiation therapy (n=1), chemotherapy (n=1), and sorafenib (n=3). Finally, 11 patients were treated with sorafenib. Nine patients (82%) received an additionally targeted therapy with sirolimus as part of their immunosuppressive regimen. Most common grade 3 adverse events included diarrhoea (46%), hand-foot skin reaction (27%), nausea, fatigue, and leucopoenia (all 18%). Sorafenib had to be discontinued in two patients due to adverse events and six additional patients required a dose adjustment. No deterioration of liver graft function occurred. Median time to progression was 4.1 months; however, patients were treated with ongoing sorafenib in case of clinical benefit (median 8.9 months). Median overall survival after initiation of sorafenib treatment was 20.1 months.

CONCLUSION

Sorafenib in combination with immunosuppression including sirolimus may be administered to patients with post-transplant hepatocellular carcinoma recurrence with acceptable toxicity and without deterioration of liver graft function.

The role of death effector domain-containing proteins in acute oxidative cell injury in hepatocytes

Apoptosis is a mechanism that regulates hepatic tissue homeostasis and contributes to both acute and chronic injury in liver disease. The apoptotic signaling cascade involves activation of the death-inducing signaling complex (DISC) and subsequent recruitment of proteins containing death effector domains (DED), which regulate downstream effector molecules. Prominent among these are the Fas-associated death domain (FADD) and the cellular caspase 8-like inhibitory protein (cFLIP), and alterations in these proteins can lead to severe disruption of physiological processes, including acute liver failure or hepatocellular carcinoma. Their role in cell signaling events independent of the DISC remains undetermined. Oxidative stress can cause cell injury from direct effects on molecules or by activating intracellular signaling pathways including the mitogen-activated protein kinases (MAPKs). In this context, prolonged activation of the cJun N-terminal kinase (JNK)/AP-1/cJun signaling pathway promotes hepatocellular apoptosis, whereas activation of the extracellular signal-regulated kinase (Erk) exerts protection. We investigated the roles of FADD and cFLIP in acute oxidant stress induced by the superoxide generator menadione in hepatocytes. Menadione resulted in dose-dependent predominantly necrotic cell death. Hepatocytes expressing a truncated, dominant-negative FADD protein were partially protected, whereas cFLIP-deficient hepatocytes displayed increased cell death from menadione. In parallel, Erk phosphorylation was enhanced in hepatocytes expressing dnFADD and decreased in cFLIP-deficient hepatocytes. Hepatocyte injury was accompanied by increased release of proapoptotic factors and increased JNK/cJun activation. Thus, FADD and cFLIP contribute to the regulation of cell death from acute oxidant stress in hepatocytes involving MAPK signaling. This implies that DED-containing proteins are involved in the regulation of cellular survival beyond their role in cell death receptor-ligand-mediated apoptosis.

Sorafenib sensitizes hepatocellular carcinoma cells to physiological apoptotic stimuli

Sorafenib increases survival rate of patients with advanced hepatocellular carcinoma (HCC). The mechanism underlying this effect is not completely understood. In this work we have analyzed the effects of sorafenib on autocrine proliferation and survival of different human HCC cell lines. Our results indicate that sorafenib in vitro counteracts autocrine growth of different tumor cells (Hep3B, HepG2, PLC-PRF-5, SK-Hep1). Arrest in S/G2/M cell cycle phases were observed coincident with cyclin D1 down-regulation. However, sorafenib's main anti-tumor activity seems to occur through cell death induction which correlated with caspase activation, increase in the percentage of hypodiploid cells, activation of BAX and BAK and cytochrome c release from mitochondria to cytosol. In addition, we observed a rise in mRNA and protein levels of the pro-apoptotic "BH3-domain only" PUMA and BIM, as well as decreased protein levels of the anti-apoptotic MCL1 and survivin. PUMA targeting knock-down, by using specific siRNAs, inhibited sorafenib-induced apoptotic features. Moreover, we obtained evidence suggesting that sorafenib also sensitizes HCC cells to the apoptotic activity of transforming growth factor-β (TGF-β) through the intrinsic pathway and to tumor necrosis factor-α (TNF) through the extrinsic pathway. Interestingly, sensitization to sorafenib-induced apoptosis is characteristic of liver tumor cells, since untransformed hepatocytes did not respond to sorafenib inducing apoptosis, either alone or in combination with TGF-β or TNF. Indeed, sorafenib effectiveness in delaying HCC late progression might be partly related to a selectively sensitization of HCC cells to apoptosis by disrupting autocrine signals that protect them from adverse conditions and pro-apoptotic physiological cytokines.

Array-based pharmacogenomics of molecular-targeted therapies in oncology

The advent of microarrays over the past decade has transformed the way genome-wide studies are designed and conducted, leading to an unprecedented speed of acquisition and amount of new knowledge. Microarray data have led to the identification of molecular subclasses of solid tumors characterized by distinct oncogenic pathways, as well as the development of multigene prognostic or predictive models equivalent or superior to those of established clinical parameters. In the field of molecular-targeted therapy for cancer, in particular, the application of array-based methodologies has enabled the identification of molecular targets with 'key' roles in neoplastic transformation or tumor progression and the subsequent development of targeted agents, which are most likely to be active in the specific molecular setting. Herein, we present a summary of the main applications of whole-genome expression microarrays in the field of molecular-targeted therapies for solid tumors and we discuss their potential in the clinical setting. An emphasis is given on deciphering the molecular mechanisms of drug action, identifying novel therapeutic targets and suitable agents to target them with, and discovering molecular markers/signatures that predict response to therapy or optimal drug dose for each patient.

Efficacy and safety of sorafenib in combination with mammalian target of rapamycin inhibitors for recurrent hepatocellular carcinoma after liver transplantation

There is currently no consensus on the most suitable treatment for the recurrence of hepatocellular carcinoma (HCC) after liver transplantation. This open, multicenter, retrospective, uncontrolled cohort study was designed to evaluate the safety and preliminary efficacy of the combined use of a mammalian target of rapamycin (mTOR) inhibitor and sorafenib in this setting. In 31 patients who suffered from HCC recurrence after liver transplantation, the immunosuppressive therapy was changed to mTOR inhibitors, and systemic treatment with sorafenib was initiated. This combination was maintained until symptomatic tumor progression, death, hepatic decompensation, or unacceptable toxicity occurred. Primary treatment efficacy was determined by overall survival and progression-free survival, and secondary efficacy was determined by the overall response rate. Toxicity parameters associated with the use of sorafenib and mTOR inhibitors were also analyzed. The overall response rate according to the Response Evaluation Criteria in Solid Tumors was 3.8% (1/26), and there was sustained stabilization of the disease in 13 additional cases (50.0%). The median overall survival was 19.3 months [95% confidence interval (CI) = 13.4-25.1 months], and the median time to progression was 6.77 months (95% CI = 2.3-11.1 months). Only 2 grade 3/4 cases of hyperglycemia and 1 case of grade 3/4 mucositis were reported, and they were possibly related to mTOR inhibitors. The most common severe adverse event probably related to sorafenib was diarrhea (12.9%). In conclusion, the coadministration of sorafenib and an mTOR inhibitor could be effective despite notable toxicity in patients with post-liver transplant HCC recurrence not suitable for radical therapy. The toxicity and efficacy need to be further evaluated in randomized controlled studies for this combination to be considered a valid option.

Signaling pathways in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the sixth most common cancer, and its mortality rate is the third highest after lung and colon cancer. Its incidence has significantly increased in the last two decades in close relation with the ubiquitous spread of viral hepatitis. HCC has a poor prognosis since less than 30% of newly diagnosed patients will be eligible for potential curative treatment. Molecular therapies such as sorafenib, a BRAF/ VEGFR/PDGFR tyrosine kinase inhibitor, have shown to improve survival in patients with advanced HCC. This recent success has spurred intensive research aimed at identifying aberrant activation of signaling pathways. This approach will probably aid to define previously unrecognized oncogenic addiction loops in HCC and in developing more effective targeted therapies.

Multivariate analysis of several molecular markers and clinicopathological features in postoperative prognosis of hepatocellular carcinoma

This study was designed to assess the impact of several molecular markers and clinicopathological characteristics on postoperative survival of patients with hepatocellular carcinoma (HCC). Postoperative clinical data of 64 patients with HCC were retrospectively analyzed. K-ras, PIK3CA, and BRAF gene mutations in surgically resected specimens of the 64 patients with HCC were detected by pyrosequencing. H-ras and XB130 protein expression was examined by immunohistochemistry. A Cox proportional hazards regression model was used for univariate and multivariate survival analyses of the clinical and pathological parameters. The mutation rates of K-ras, PIK3CA, and BRAF genes in HCC were found to be 4.69%, 1.56%, and 0%, respectively. Positive expression rate of XB130 and H-ras in HCC was 75.0% and 93.8%, respectively. Univariate analysis revealed that clinicopathological factors impacting postoperative prognosis of patients with HCC include clinical stage, tumor diameter, and postoperative transcatheter arterial embolization therapy for HCC. Meanwhile, multivariate analysis showed that clinical stage (relative risk [RR]: 6.420, P = 0.013) and tumor diameter (RR: 1.498, P = 0.014) were independent factors impacting postoperative survival of patients with HCC. These findings indicate that the clinical stage and tumor diameter are independent risk factors impacting postoperative survival of patients with HCC. Gene mutations of K-ras and PIK3CA and protein expression of XB130 and H-ras are not associated with the postoperative prognosis of patients with HCC.

Sorafenib: complexities of Raf-dependent and Raf-independent signaling are now unveiled

Hepatocellular carcinoma (HCC) is the most common primary cancer worldwide. The only current drug available for clinical treatment of HCC is sorafenib, which inhibits multiple signaling kinases including Raf family members, platelet-derived growth factor receptor, vascular endothelial growth factor receptors 1 and 2, c-Kit, and Fms-like tyrosine kinase 3. Many studies have revealed that the mechanism underlying the antitumor effect of sorafenib is complex. Because sorafenib inhibits C-Raf more potently than B-Raf, the therapeutic efficacy of sorafenib is strongly influenced by the relative expression and activity of B-Raf and C-Raf and the complex interactions between these factors. Moreover, Rafindependent signaling mechanisms have recently emerged as important pathways of sorafenib-induced cell death. Basic research studies have suggested that using sorafenib as part of a combination therapy may improve its effect, although this has yet to be confirmed by clinical evidence. Further studies of the functional mechanism of sorafenib are required to advance the development of targeted therapy for HCC. To aid future work on sorafenib, we here review the current literature pertaining to sorafenib signaling and its clinical efficacy in both monotherapy and combination therapy.

PKI-587 and sorafenib targeting PI3K/AKT/mTOR and Ras/Raf/MAPK pathways synergistically inhibit HCC cell proliferation

BACKGROUND

Deregulated Ras/Raf/MAPK and PI3K/AKT/mTOR signaling pathways are found in hepatocellular carcinoma (HCC). This study aimed to test the inhibitory effects of PKI-587 and sorafenib as single agents or in combination on HCC (Huh7 cell line) proliferation.

MATERIALS AND METHODS

(3)H-thymidine incorporation and MTT assay were used to assess Huh7 cell proliferation. Phosphorylation of the key enzymes in the Ras/Raf/MAPK and PI3K/AKT/mTOR pathways was detected by Western blot.

RESULTS

We found that PKI-587 is a more potent PI3K/mTOR inhibitor than PI-103. Combination of PKI-587 and sorafenib was a more effective inhibitor of Huh7 proliferation than the combination of PI-103 and sorafenib. Combination of PKI-587 and sorafenib synergistically inhibited epidermal growth factor (EGF)-stimulated Huh7 proliferation compared with monodrug therapy. EGF increased phosphorylation of Ras/Raf downstream signaling proteins MEK and ERK; EGF-stimulated activation was inhibited by sorafenib. However, sorafenib, as a single agent, increased AKT (Ser473) phosphorylation. EGF-stimulated AKT (ser473) activation was inhibited by PKI-587. PKI-587 is a potent inhibitor of AKT (Ser473), mTOR (Ser2448), and S6K (Thr389) phosphorylation; in contrast, rapamycin stimulated mTOR complex 2 substrate AKT(Ser473) phosphorylation although it inhibited mTOR complex 1 substrate S6K phosphorylation. PKI-587, as a single agent, stimulated MEK and ERK phosphorylation. However, when PKI-587 and sorafenib were used in combination, they inhibited all the tested kinases in the Ras/Raf /MAPK and PI3K/AKT/mTOR pathways.

CONCLUSION

The combination of PKI-587 and sorafenib has the advantage over monodrug therapy on inhibition of HCC cell proliferation by blocking both PI3K/AKT/mTOR and Ras/Raf/MAPK signaling pathways.

Hypermethylation-modulated downregulation of RASSF1A expression is associated with the progression of esophageal cancer

BACKGROUND AND AIMS

Chromosome 3p21 is an important locus harboring critical tumor suppressor genes (TSGs) implicated in the pathogenesis of multiple tumors including esophageal carcinoma (EC). Aberrant promoter methylation is a fundamental mechanism of inactivation of TSGs in cancer. RASSF1A, a candidate tumor suppressor gene, recently cloned from the lung tumor locus at 3p21.3, is frequently inactivated by hypermethylation of its promoter region in a number of malignancies. We undertook this study to investigate the methylation status of RASSF1A and its significance in esophageal squamous cell carcinoma (ESCC).

METHODS

Real-time RT-PCR and real-time methylation-specific PCR (real-time MSP) were used to detect RASSF1A expression and the methylation status of the RASSF1A promoter, respectively, in 124 primary ESCC tissues.

RESULTS

Hypermethylation, partial methylation and unmethylation of the promoter region of RASSF1A were detected in 56 (45.2%), 23 (18.6%) and 45 (36.2%) of 124 ESCC samples, respectively. Unmethylation of the promoter region of RASSF1A was detected in 119 (96%) of the 124 corresponding noncancerous tissues. Five (4.0%) of 124 noncancerous tissues showed partial methylation. The presence of hypermethylation was statistically associated with loss of RASSF1A mRNA expression in primary ESCC (p <0.05). There were statistically significant correlations between the presence of hypermethylation and regional lymph node involvement (p=0.000), histological differentiation (p=0.009) and tumor stage (p=0.000).

CONCLUSIONS

Our results suggest that RASSF1A may be one of the ESCC-related TSGs located at 3p21, and hypermethylation of the CpG island promoter of the RASSF1A is associated with the progression of ESCC.

The metabolic and toxicological considerations for mTOR inhibitors in the treatment of hepatocarcinoma

INTRODUCTION

Hepatocellular carcinoma (HCC) is a major health problem worldwide. Several molecular pathways involved in HCC growth and progression have recently been identified. Rapamycin analogs are able to inhibit one of the most active oncogenic molecular pathways in HCC cells: the mammalian target of rapamycin (mTOR) pathway.

AREAS COVERED

In this review, the authors analyze the principal molecular features of the mTOR pathway and the use of rapamycin analogs in the treatment of hepatocarcinoma. The article also looks at the reoccurrence of HCC following liver transplantation as well as after the treatment of de novo neoplasms. Finally, the authors discuss the advantage of using a combined HCC pharmacological therapy to obtain a synergistic effect on tumor mass.

EXPERT OPINION

Among the available options for the treatment of advanced-stage HCC, mTOR pathway inhibitors show great promise. Once these agents have their safety and efficacy confirmed, in the treatment of liver disease, their use should be considered in patients affected by HCC. This should especially be the case for those who have had liver transplants or suffered with de novo tumors. Moreover, the authors believe that mTOR inhibitors could be used in a combined pharmacological approach to improve HCC molecular-targeted therapy by producing a multiple-level block of tumor intracellular signaling.

Molecular targets and oxidative stress biomarkers in hepatocellular carcinoma: an overview

Hepatocellular carcinoma (HCC) is a complex and heterogeneous tumor with multiple genetic aberrations. Several molecular pathways involved in the regulation of proliferation and cell death are implicated in the hepatocarcinogenesis. The major etiological factors for HCC are both hepatitis B virus (HBV) and hepatitis C virus infection (HCV). Continuous oxidative stress, which results from the generation of reactive oxygen species (ROS) by environmental factors or cellular mitochondrial dysfunction, has recently been associated with hepatocarcinogenesis. On the other hand, a distinctive pathological hallmark of HCC is a dramatic down-regulation of oxido-reductive enzymes that constitute the most important free radical scavenger systems represented by catalase, superoxide dismutase and glutathione peroxidase. The multikinase inhibitor sorafenib represents the most promising target agent that has undergone extensive investigation up to phase III clinical trials in patients with advanced HCC. The combination with other target-based agents could potentiate the clinical benefits obtained by sorafenib alone. In fact, a phase II multicenter study has demonstrated that the combination between sorafenib and octreotide LAR (So.LAR protocol) was active and well tolerated in advanced HCC patients. The detection of molecular factors predictive of response to anti-cancer agents such as sorafenib and the identification of mechanisms of resistance to anti-cancer agents may probably represent the direction to improve the treatment of HCC.

Hepatocellular carcinoma and liver transplantation: clinical perspective on molecular targeted strategies

Hepatocellular carcinoma (HCC) has an aggressive clinical course with frequent recurrence and metastasis. Orthotopic liver transplantation has been the only curative tool for unresectable HCC; therefore, recent advances in molecular targeted therapy may improve the prognosis of HCC. The multiple kinase inhibitor sorafenib and the macrolide antibiotic rapamycin are currently the most promising agents for treating unresectable HCC. A large population-based clinical trial revealed that sorafenib significantly prolonged the overall survival of HCC patients. However, subsequent clinical studies showed that sorafenib rarely reduced tumor volume and inadequately prolonged survival of patients with severe liver damage. To improve its therapeutic effect, the development of a predictive biomarker and a sorafenib-based combination is awaited. Another molecular targeting agent, rapamycin, has now been considered as a putative agent for preventing tumor recurrence in post-liver transplantation HCC patients, because it not only has immunosuppressive activity but also exerts an anti-tumor effect. In the near future, a combination of molecular targeting agents, such as sorafenib and rapamycin, may become a standard protocol for treating unresectable HCC. For specifying cases with more effective and less harmful modalities, further investigation in clinical and basic research to identify unexpected effects are needed.

An inducible kras(V12) transgenic zebrafish model for liver tumorigenesis and chemical drug screening

Because Ras signaling is frequently activated by major hepatocellular carcinoma etiological factors, a transgenic zebrafish constitutively expressing the kras^V12 oncogene in the liver was previously generated by our laboratory. Although this model depicted and uncovered the conservation between zebrafish and human liver tumorigenesis, the low tumor incidence and early mortality limit its use for further studies of tumor progression and inhibition. Here, we employed a mifepristone-inducible transgenic system to achieve inducible kras^V12 expression in the liver. The system consisted of two transgenic lines: the liver-driver line had a liver-specific fabp10 promoter to produce the LexPR chimeric transactivator, and the Ras-effector line contained a LexA-binding site to control EGFP-kras^V12 expression. In double-transgenic zebrafish (driver-effector) embryos and adults, we demonstrated mifepristone-inducible EGFP-kras^V12 expression in the liver. Robust and homogeneous liver tumors developed in 100% of double-transgenic fish after 1 month of induction and the tumors progressed from hyperplasia by 1 week post-treatment (wpt) to carcinoma by 4 wpt. Strikingly, liver tumorigenesis was found to be ‘addicted’ to Ras signaling for tumor maintenance, because mifepristone withdrawal led to tumor regression via cell death in transgenic fish. We further demonstrated the potential use of the transparent EGFP-kras^V12 larvae in inhibitor treatments to suppress Ras-driven liver tumorigenesis by targeting its downstream effectors, including the Raf-MEK-ERK and PI3K-AKT-mTOR pathways. Collectively, this mifepristone-inducible and reversible kras^V12 transgenic system offers a novel model for understanding hepatocarcinogenesis and a high-throughput screening platform for anti-cancer drugs.

Radiologic complete response with sirolimus and sorafenib in a hepatocellular carcinoma patient who relapsed after orthotopic liver transplantation

BACKGROUND

No standard therapies have been established for the treatment of recurrent hepatocellular carcinoma (HCC) after liver transplantation.

DISCUSSION

Sirolimus is a mTOR inhibitor which has been used as an immunosuppressive medication in patients who are at high risk of tumor reoccurrence after liver transplantation. Sorafenib is a multikinase inhibitor approved for the treatment of advanced HCC. However the role of sorafenib in patients with HCC reoccurrence after liver transplantation is unclear.

RESULTS

Combination of sirolimus and sorafenib appears to have synergistic effect when treating HCC in preclinical settings. We report a case of a post-liver transplant patient treated with sorafenib and sirolimus for hepatic HCC recurrence who exhibited complete radiologic response after 5A months of therapy.

Molecular classification of hepatocellular carcinoma anno 2011

Hepatocellular carcinoma has an increasing incidence and high mortality. Treatment options are limited if the disease is not diagnosed in its early stage. The natural course of the disease is aggressive but not always predictable. Molecular profiling is a promising tool for classification in order to optimize prognosis prediction and treatment for an individual patient. In the last decade a large amount of studies has been conducted to better classify hepatocellular carcinomas. The focus of this review is on implications of molecular classification for prognosis and therapeutic decision making in HCC patients. Most studies used microarray technique for genome wide profiling, but other methods to detect genomic changes and microRNA are gaining interest. The whole genome profiling studies identified differences in affected signalling and tried to relate this to prognosis. Some common subgroups were identified, such as the proliferation cluster and the beta-catenin cluster. However, there is still little overlap between most studies. Better study design and bio-informatical analysis might help in this context.

A signature of six genes highlights defects on cell growth and specific metabolic pathways in murine and human hepatocellular carcinoma

Hepatocellular carcinoma (HCC) represents a major health problem as it afflicts an increasing number of patients worldwide. Albeit most of the risk factors for HCC are known, this is a deadly syndrome with a life expectancy at the time of diagnosis of less than 1 year. Definition of the molecular principles governing the neoplastic transformation of the liver is an urgent need to facilitate the clinical management of patients, based on innovative methods to detect the disease in its early stages and on more efficient therapies. In the present study, we have combined the analysis of a murine model and human samples of HCC to identify genes differentially expressed early in the process of hepatocarcinogenesis, using a microarray-based approach. Expression of 190 genes was impaired in murine HCC from which 65 were further validated by low-density array real-time polymerase chain reaction (RT-PCR). The expression of the best 45 genes was then investigated in human samples resulting in 18 genes in which expression was significantly modified in HCC. Among them, JUN, methionine adenosyltransferase 1A and 2A, phosphoglucomutase 1, and acyl CoA dehydrogenase short/branched chain indicate defective cell proliferation as well as one carbon pathway, glucose and fatty acid metabolism, both in HCC and cirrhotic liver, a well-known preneoplastic condition. These alterations were further confirmed in public transcriptomic datasets from other authors. In addition, vasodilator-stimulated phosphoprotein, an actin-associated protein involved in cytoskeleton remodeling, was also found to be increased in the liver and serum of cirrhotic and HCC patients. In addition to revealing the impairment of central metabolic pathways for liver homeostasis, further studies may probe the potential value of the reported genes for the early detection of HCC.

Hepatocellular carcinoma: molecular and genomic guideline for the clinician

Understanding of the genetic changes and molecular signaling pathways that are active in hepatocellular carcinoma has improved substantially over the last decade. As more information becomes available, it is clear that the prognostication of hepatocellular carcinoma will soon include molecular and genomic "fingerprints" that are unique to each cancer, which will allow more personalized treatment plans for patients as more targeted therapies become available. This article discusses the molecular and genomic changes that are important in hepatocellular carcinoma in order for clinicians to understand the current and forthcoming treatment options for patients with liver cancer.

MicroRNA-based classification of hepatocellular carcinoma and oncogenic role of miR-517a

BACKGROUND & AIMS

Hepatocellular carcinoma (HCC) is a heterogeneous tumor that develops via activation of multiple pathways and molecular alterations. It has been a challenge to identify molecular classes of HCC and design treatment strategies for each specific subtype. MicroRNAs (miRNAs) are involved in HCC pathogenesis, and their expression profiles have been used to classify cancers. We analyzed miRNA expression in human HCC samples to identify molecular subclasses and oncogenic miRNAs.

METHODS

We performed miRNA profiling of 89 HCC samples using a ligation-mediated amplification method. Subclasses were identified by unsupervised clustering analysis. We identified molecular features specific for each subclass using expression pattern (Affymetrix U133 2.0; Affymetrix, Santa Clara, CA), DNA change (Affymetrix STY Mapping Array), mutation (CTNNB1), and immunohistochemical (phosphor[p]-protein kinase B, p-insulin growth factor-IR, p-S6, p-epidermal growth factor receptor, β-catenin) analyses. The roles of selected miRNAs were investigated in cell lines and in an orthotopic model of HCC.

RESULTS

We identified 3 main clusters of HCCs: the wingless-type MMTV integration site (32 of 89; 36%), interferon-related (29 of 89; 33%), and proliferation (28 of 89; 31%) subclasses. A subset of patients with tumors in the proliferation subclass (8 of 89; 9%) overexpressed a family of poorly characterized miRNAs from chr19q13.42. Expression of miR-517a and miR-520c (from ch19q13.42) increased proliferation, migration, and invasion of HCC cells in vitro. MiR-517a promoted tumorigenesis and metastatic dissemination in vivo.

CONCLUSIONS

We propose miRNA-based classification of 3 subclasses of HCC. Among the proliferation class, miR-517a is an oncogenic miRNA that promotes tumor progression. There is rationale for developing therapies that target miR-517a for patients with HCC.

Targeted therapies for hepatocellular carcinoma

Unlike most solid tumors, the incidence and mortality of hepatocellular carcinoma (HCC) have increased in the United States and Europe in the past decade. Most patients are diagnosed at advanced stages, so there is an urgent need for new systemic therapies. Sorafenib, a tyrosine kinase inhibitor (TKI), has shown clinical efficacy in patients with HCC. Studies in patients with lung, breast, or colorectal cancers have indicated that the genetic heterogeneity of cancer cells within a tumor affect its response to therapeutics designed to target specific molecules. When tumor progression requires alterations in specific oncogenes (oncogene addiction), drugs that selectively block their products might slow tumor growth. However, no specific oncogene addictions are yet known to be implicated in HCC progression, so it is important to improve our understanding of its molecular pathogenesis. There are currently many clinical trials evaluating TKIs for HCC, including those tested in combination with (eg, erlotinib) or compared with (eg, linifanib) sorafenib as a first-line therapy. For patients who do not respond or are intolerant to sorafenib, TKIs such as brivanib, everolimus, and monoclonal antibodies (eg, ramucirumab) are being tested as second-line therapies. There are early stage trials investigating the efficacy for up to 60 reagents for HCC. Together, these studies might change the management strategy for HCC, and combination therapies might be developed for patients with advanced HCC. Identification of oncogenes that mediate tumor progression, and trials that monitor their products as biomarkers, might lead to personalized therapy; reagents that interfere with signaling pathways required for HCC progression might be used to treat selected populations, and thereby maximize the efficacy and cost benefit.

Everolimus augments the effects of sorafenib in a syngeneic orthotopic model of hepatocellular carcinoma

Sorafenib targets the Raf/mitogen-activated protein kinase, VEGF, and platelet-derived growth factor pathways and prolongs survival patients in advanced hepatocellular carcinoma (HCC). Everolimus inhibits the mammalian target of rapamycin, a kinase overactive in HCC. To investigate whether the antitumor effects of these agents are additive, we compared a combined and sequential treatment regimen of everolimus and sorafenib with monotherapy. After hepatic implantation of Morris Hepatoma (MH) cells, rats were randomly allocated to everolimus (5 mg/kg, 2×/week), sorafenib (7.5 mg/kg/d), combined everolimus and sorafenib, sequential sorafenib (2 weeks) then everolimus (3 weeks), or control groups. MRI quantified tumor volumes. Erk1/2, 4E-BP1, and their phosphorylated forms were quantified by immunoblotting. Angiogenesis was assessed in vitro by aortic ring and tube formation assays, and in vivo with Vegf-a mRNA and vascular casts. After 35 days, tumor volumes were reduced by 60%, 85%, and 55%, relative to controls, in everolimus, the combination, and sequential groups, respectively (P < 0.01). Survival was longest in the combination group (P < 0.001). Phosphorylation of 4E-BP1 and Erk1/2 decreased after everolimus and sorafenib, respectively. Angiogenesis decreased after all treatments (P < 0.05), although sorafenib increased Vegf-a mRNA in liver tumors. Vessel sprouting was abundant in control tumors, lower after sorafenib, and absent after the combination. Intussusceptive angiogenic transluminal pillars failed to coalesce after the combination. Combined treatment with everolimus and sorafenib exerts a stronger antitumoral effect on MH tumors than monotherapy. Everolimus retains antitumoral properties when administered sequentially after sorafenib. This supports the clinical use of everolimus in HCC, both in combination with sorafenib or after sorafenib.

Oleate-mediated activation of phospholipase D and mammalian target of rapamycin (mTOR) regulates proliferation and rapamycin sensitivity of hepatocarcinoma cells

AIMS/HYPOTHESIS

A high-fat diet and obesity are associated with increased risk of liver cancer. Because increased delivery of NEFA to the liver occurs in these conditions, we investigated the involvement of the unsaturated fatty acid oleate in hepatocarcinoma cell proliferation using human-derived hepatocarcinoma cell lines as model systems.

METHODS

Western blotting, FACS analysis and [(3)H]thymidine incorporation were used to study the signalling pathways and the proliferation of cells cultured for up to 72 h with or without a concentration of oleate considered to be relevant to human pathophysiology (50 μmol/l) or a concentration considered elevated (1 mmol/l).

RESULTS

In HepG2 cells, proliferation was increased in the presence of 50 μmol/l oleate, but was decreased at 1 mmol/l. This differential effect was correlated with the activation of the mammalian target of rapamycin complex 1 (mTORC1) and with increased translation of cell cycle regulators. Oleate-mediated mTORC1 activation required phospholipase D activation, which produces phosphatidic acid and is known to render mTORC1 rapamycin resistant. Remarkably, rapamycin resistance was found to affect specifically the mTORC1/eukaryotic initiation factor 4E-binding protein 1 (4E-BP1) branch of the mTORC1 pathway in the presence of 50 μmol/l oleate. Furthermore, inhibition of phosphatidic acid production abolished oleate-induced increases in mTORC1 activity and cyclin A production. Importantly, the same differential effects of oleate on mTORC1 activation, cell cycle regulators and rapamycin resistance were found in SK-Hep1 cells.

CONCLUSIONS/INTERPRETATION

Oleate stimulates mTORC1 activation and rapamycin resistance. We propose that rapamycin-derived mTOR inhibitors are likely to be of limited therapeutic use to restrain hepatic tumour growth, particularly in the context of associated obesity.

Angiogenesis in chronic liver disease and its complications

Nowadays, liver cancer, cirrhosis and other liver-related diseases are the fifth most common cause of mortality in the UK. Furthermore, chronic liver diseases (CLDs) are one of the major causes of death, which are still increasing year-on-year. Therefore, knowledge about the pathophysiology of CLDs and its complications is of uttermost importance. The goal of this review is to clarify the role of angiogenesis in the disease progression of various liver diseases. Looking closer at the pathophysiology of portal hypertension (PH), fibrosis, cirrhosis, non-alcoholic steatohepatitis (NASH) and hepatocellular carcinoma (HCC), we find that angiogenesis is a recurring factor in the disease progression. In PH, several factors involved in its pathogenesis, such as hypoxia, oxidative stress, inflammation and shear stress are potential mediators for the angiogenic response. The progression from fibrosis to cirrhosis, the end-point of CLDs, is distinguished by a prolonged inflammatory and fibrogenic process that leads to an abnormal angioarchitecture distinctive for cirrhosis. In several stages of NASH, a link might be made between the disease progression and hepatic microvasculature changes. HCC is one of the most vascular solid tumours in which angiogenesis plays an important role in its development, progression and metastasis. The close relationship between the progression of CLDs and angiogenesis emphasises the need for anti-angiogenic therapy as a tool for blocking or slowing down the disease progression. The fact that angiogenesis plays a pivotal role in CLDs gives rise to new opportunities for treating CLDs and its complications.

MDM2 antagonist can inhibit tumor growth in hepatocellular carcinoma with different types of p53 in vitro

BACKGROUND AND AIMS

Nutlin-3, a selective small-molecule inhibitor of the p53-MDM2 interaction, has been shown to have antitumor activities in various tumors with wild-type p53. However, its effect on hepatocellular carcinoma (HCC) with different types of p53 remains unclear. This study is designed to determine nutlin-3's antitumor efficacy and underlying mechanisms of action in human HCC cells.

METHODS

Cell viability assay, cell cycle analysis, apoptosis assay, western blot, co- immunoprecipitation and siRNA experiments were analyzed in three human HCC cells. Anti-tumoral effects of nutlin-3 targeting the p53 and p73 pathways were evaluated in HCC cell lines.

RESULTS

Nutlin-3 exerted the greatest anti-tumoral effect to three human HCC cells with wild-type p53, mutant p53 and p53-null. Nutlin-3 not only upregulated p53 in HepG2 cells, but also p73 in Huh7 and Hep3B cells, and disrupted p53-MDM2 and p73-MDM2 complexes in HCC cells. The compound inhibited cell proliferation, induced G0/G1 phase arrest, decreased the levels of CyclinD1, CyclinE, CDK2, CDK4, PCNA and E2F-1, and increased the levels of p21 and p27. It also induced apoptosis, increased the Bax/Bcl-2 ratio, then activated caspase-9 and caspase-3.

CONCLUSIONS

Nutlin-3 has significant anticancer effects against human HCC cells, regardless of p53 status, indicating that it is a promising therapy for human hepatocellular carcinoma.

PI-103 and sorafenib inhibit hepatocellular carcinoma cell proliferation by blocking Ras/Raf/MAPK and PI3K/AKT/mTOR pathways

BACKGROUND

Aberrant Ras/Raf/MAPK and PI3K/AKT/mTOR signaling pathways are found in hepatocellular carcinoma (HCC). This study reports how sorafenib (a multi-kinase inhibitor) and PI-103 (a dual PI3K/mTOR inhibitor) alone and in combination inhibit the proliferation of the HCC cell line, Huh7.

MATERIALS AND METHODS

Huh7 proliferation was assayed by 3H-thymidine incorporation and by MTT assay. Western blot was used to detect phosphorylation of the key enzymes in the Ras/Raf and PI3K pathways.

RESULTS

Sorafenib and PI-103, as single agents inhibited Huh7 proliferation and epidermal growth factor (EGF)-stimulated Huh7 proliferation in a dose-dependent fashion; the combination of sorafenib and PI-103 produced synergistic effects. EGF increased phosphorylation of MEK and ERK, key Ras/Raf downstream signaling proteins; this activation was inhibited by sorafenib. However, sorafenib as a single agent increased AKT(Ser473) and mTOR phosphorylation. EGF-stimulated activation of PI3K/AKT/mTOR pathway components was inhibited by PI-103. PI-103 is a potent inhibitor of AKT(Ser473) phosphorylation; in contrast, rapamycin stimulated AKT(Ser473) phosphorylation. It was found that PI-103, as a single agent, stimulated MEK and ERK phosphorylation. However, the combination of sorafenib and PI-103 caused inhibition of all the tested kinases in the Ras/Raf and PI3K pathways.

CONCLUSION

The combination of sorafenib and PI-103 can significantly inhibit EGF-stimulated Huh7 proliferation by blocking both Ras/Raf/MAPK and PI3K/AKT/mTOR pathways.