Activation of mitogen-activated protein kinases/extracellular signal-regulated kinases in human hepatocellular carcinoma

Glabridin arrests cell cycle and inhibits proliferation of hepatocellular carcinoma by suppressing braf/MEK signaling pathway

Glabridin, an isoflavone isolated from licorice, owns a variety of pharmacological effects. Several reports have demonstrated that glabridin could regulate multiple cellular signaling pathways to inhibit the progression of cancer. However, the target proteins have not been elucidated yet. We used shape screening and induced fit docking to screen the protein data bank against glabridin. Braf and MEK1/2, important intermediate molecules of the braf/MEK cascade, were identified as the potential targets of glabridin. The experimental data showed that glabridin could inhibit the phosphorylation of MEK1/2 and the phosphorylation levels of downstream molecules including ERK1/2 and transcription factors ATF1 and CREB, but had no effect on the phosphorylation of braf. In particular, the in vitro pull-down assay indicated that glabridin selectively bound to braf and MEK1/2. What is more, exposure to glabridin significantly suppressed the proliferation of hepatocellular carcinoma HepG2 cell line. In addition, glabridin might arrest cell cycle in G1 through downregulation of cyclinD3, CDK2, and CDK4. In conclusion, glabridin is a potential multi-molecule-targeting inhibitor in the field of clinical prevention or treatment of cancer.

Evaluation of dose-efficacy of sorafenib and effect of transarterial chemoembolization in hepatocellular carcinoma patients: a retrospective study

BACKGROUND

Transarterial chemoembolization (TACE) and sorafenib are the therapeutic standard for intermediate and advanced stage hepatocellular carcinoma (HCC) patients respectively. High costs with adverse events (AE) of sorafenib might limit sorafenib dosage, further affecting therapeutic response. To attain greatest benefit, we evaluated the efficacy of different doses and effect of TACE during and after sorafenib discontinuation in patients representing Child-Pugh Classification Class A with venous or extra-hepatic invasion.

METHODS

A total 156 patients met the criteria and were divided into Groups I (n = 52) accepting 800 mg/day; II (n = 58) accepting 800 mg/day and reduced to 400 mg/day owing to AE; and III (n = 46) accepting 400 mg/day. TACE was performed during and after sorafenib discontinuation and therapeutic response bimonthly to four-monthly was rated thereafter.

RESULTS

Median duration of sorafenib treatment and patients' survival were 4.00 ± 0.45 and 7.50 ± 1.44 months in all cases; 2.50 ± 0.90 and 5.00 ± 1.10 months in Group I; 5.50 ± 1.27 and 16.50 ± 1.86 months in Group II; 4.00 ± 0.94 and 6.50 ± 2.49 months in Group III. Group II presented the best response and survival benefit (p = 0.010 and p = 0.011 respectively). Child-Pugh Classification score 5 (Hazard Ratio = 0.492, p = 0.049), absent AE (3.423, p = 0.015), tumor numbers ≤ 3 (0.313, p = 0.009), sorafenib duration ≤ 1 cycle (3.694, p = 0.004), and absent TACE (3.197, p = 0.008) significantly correlated with patient survival. TACE benefit appeared in separate and total cases during (p = 0.002, p = 0.595, p = 0.074, p = 0.002 respectively) and after discontinuation of sorafenib administration (p = 0.001, p = 0.034, p = 0.647, p = 0.001 respectively).

CONCLUSIONS

Low-dosage sorafenib not only appeared tolerable and lowered economic pressure but also provided satisfactory results. TACE benefited patient's survival during and after sorafenib discontinuation.

Design, synthesis and antimetastatic evaluation of 1-benzothiazolylphenylbenzotriazoles for photodynamic therapy in oral cancer cells

We have designed and synthesized a new series of 1-benzothiazolylphenylbenzotriazoles 9a–p and studied their antimetastatic mechanism involved in photosensitive effects induced by UVA in oral cancer cell Ca9-22.

Safety and effectiveness of sorafenib in Japanese patients with hepatocellular carcinoma in daily medical practice: interim analysis of a prospective postmarketing all-patient surveillance study

BACKGROUND

Sorafenib was approved for treatment of unresectable hepatocellular carcinoma (HCC) in Japan in 2009. A prospective postmarketing all-patient surveillance (PMS) study was requested by Japanese authorities to confirm safety and effectiveness of sorafenib in Japanese HCC population.

METHODS

Patients with unresectable HCC treated with sorafenib were followed up for 12 months. Data on patient demographic characteristics, treatment status, clinical outcome, and adverse events (AEs) were collected.

RESULTS

This interim analysis included 1109 and 1065 patients evaluable for safety and effectiveness, respectively. Most patients (83.4 %) received the recommended initial dose of 400 mg twice daily. After a follow-up of 12-months, 89.8 % had discontinued treatment, most because of AEs (44.5 %) or progression (33.8 %). The most common drug-related adverse events (DRAE) were hand-foot skin reaction (51.4 %), liver dysfunction (26.4 %), diarrhea (25.1 %), and hypertension (21.6 %). The median overall survival (OS) was 348 days [95 % confidence interval (CI) 299-389 days], and the median duration of treatment was 87 days (95 % CI 78-98 days). Multivariate analyses identified baseline prognostic factors for longer OS, including female sex, low Child-Pugh score, Eastern Cooperative Oncology Group performance status 0, tumor stage I/II/III, low aspartate aminotransferase level, high hemoglobin level, hepatitis C and history of surgical resection.

CONCLUSIONS

In general, the safety and effectiveness findings in this PMS were consistent with findings from previous clinical studies. Sorafenib was well tolerated and clinically useful for Japanese patients.

CLINICAL TRIAL REGISTRATION NUMBER

NCT01411436.

Sorafenib enriches epithelial cell adhesion molecule-positive tumor initiating cells and exacerbates a subtype of hepatocellular carcinoma through TSC2-AKT cascade

Sorafenib is a specific adenosine triphosphate-competitive RAF inhibitor used as a first-line treatment of advanced hepatocellular carcinoma (HCC). However, the responses are variable, reflecting heterogeneity of the disease, while the resistance mechanism remains poorly understood. Here, we report that sorafenib treatment can exacerbate disease progression in both patient-derived xenografts and cell line-derived xenografts and that the therapeutic effect of the drug inversely covaries to the ratio of epithelial cell adhesion molecule-positive cells, which may be tumor initiating cells in HCC. The TSC2-AKT cascade mediates this sorafenib resistance. In response to sorafenib treatment, formation of the TSC1/2 complex is enhanced, causing increased phosphorylation of AKT, which contributes to up-regulation of "stemness"-related genes in epithelial cell adhesion molecule-positive cells and enhancement of tumorigenicity. The expression of TSC2 negatively correlated with prognosis in clinical sorafenib therapy. Furthermore, all-trans retinoic acid decreased AKT activity, reduced the epithelial cell adhesion molecule-positive cell population enriched by sorafenib, and potentiated the therapeutic effect of sorafenib in the patient-derived xenograft model.

CONCLUSION

Our findings suggest that a subtype of HCC is not suitable for sorafenib therapy; this resistance to sorafenib can be predicted by the status of TSC2, and agents inducing differentiation of tumor initiating cells (e.g., all-trans retinoic acid) should improve the prognosis of this subtype of HCC.

Peroxiredoxin II promotes hepatic tumorigenesis through cooperation with Ras/Forkhead box M1 signaling pathway

The current study was carried out to define the involvement of Peroxiredoxin (Prx) II in progression of hepatocellular carcinoma (HCC) and the underlying molecular mechanism(s). Expression and function of Prx II in HCC was determined using H-ras(G12V)-transformed HCC cells (H-ras(G12V)-HCC cells) and the tumor livers from H-ras(G12V)-transgenic (Tg) mice and HCC patients. Prx II was upregulated in H-ras(G12V)-HCC cells and H-ras(G12V)-Tg mouse tumor livers, the expression pattern of which highly similar to that of forkhead Box M1 (FoxM1). Moreover, either knockdown of FoxM1 or site-directed mutagenesis of FoxM1-binding site of Prx II promoter significantly reduced Prx II levels in H-ras(G12V)-HCC cells, indicating FoxM1 as a direct transcription factor of Prx II in HCC. Interestingly, the null mutation of Prx II markedly decreased the number and size of tumors in H-ras(G12V)-Tg livers. Consistent with this, knockdown of Prx II in H-ras(G12V)-HCC cells reduced the expression of cyclin D1, cell proliferation, anchorage-independent growth and tumor formation in athymic nude mice, whereas overexpression of Prx II increased or aggravated the tumor phenotypes. Importantly, the expression of Prx II was correlated with that of FoxM1 in HCC patients. The activation of extracellular signal-related kinase (ERK) pathway and the expression of FoxM1 and cyclin D1 were highly dependent on Prx II in H-ras(G12V)-HCC cells and H-ras(G12V)-Tg livers. Prx II is FoxM1-dependently-expressed antioxidant in HCC and function as an enhancer of Ras(G12V) oncogenic potential in hepatic tumorigenesis through activation of ERK/FoxM1/cyclin D1 cascade.

Vertical Targeting of AKT and mTOR as Well as Dual Targeting of AKT and MEK Signaling Is Synergistic in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the sixth most common cancer, and the third most common cause of cancer related death worldwide. The multi-kinase inhibitor Sorafenib represents the only systemic treatment option until today, and results from clinical trials with allosteric mTOR inhibitors were sobering. Since the PI3K/AKT/mTOR and RAF/MEK/ERK signaling pathways are frequently upregulated in HCC, we have analyzed the effects of AKT inhibitor MK-2206, MEK inhibitor AZD6244 (ARRY 142886) and mTOR kinase inhibitor AZD8055, given as single drugs or in combination, on proliferation and apoptosis of three HCC cell lines in vitro. We show that all three inhibitor combinations synergistically inhibit proliferation of the three HCC cell lines, with the strongest synergistic effect observed after vertical inhibition of AKT and mTORC1/2. We demonstrate that AKT kinase activity is restored 24h after blockade of mTORC1/2 by increased phosphorylation of T308, providing a rationale for combined targeting of AKT and mTOR inhibition in HCC. Our data suggest that a combination of inhibitors targeting those respective pathways may be a viable approach for future application in patients with hepatocellular carcinoma.

Expression of pERK and VEGFR-2 in advanced hepatocellular carcinoma and resistance to sorafenib treatment

BACKGROUND & AIMS

The study aimed to evaluate the tissue expression of molecules involved in intracellular signalling pathways as predictors of response to sorafenib in advanced hepatocellular carcinoma (HCC).

METHODS

We considered 77 patients enrolled into three prospective trials of sorafenib treatment for whom pretreatment tumour tissue was available. The tissue expression of β-catenin, glutamine synthetase (GS), phosphorylated extracellular signal regulated kinase (pERK), phosphorylated v-akt murine thymoma viral oncogene homolog (pAKT) and vascular endothelial growth factor receptor-2 (VEGFR-2) was analysed by immunostaining. Stains were scored semiquantitatively and compared with a reference group of 56 untreated HCCs.

RESULTS

Overall, the expression of antigens was comparable between treated and untreated patients. Shorter progression-free survival (PFS) and overall survival (OS) were associated with increased pERK staining (≥ 2+ scores) (PFS: 75th percentile 4.4 vs 8.4 months; P = 0.01; OS: 75th percentile 7.0 vs 15.0 months; P = 0.005) and VEGFR-2 staining (≥ 2+ scores) (PFS: 75th percentile 3.8 vs 7.0 months; P = 0.039; OS: 75th percentile 6.3 vs 15.0 months; P = 0.004). At multivariate analysis, both pERK and VEGFR-2 staining maintained an independent effect on OS (HR 2.09; 95% CI, 1.13-3.86, P = 0.019 and HR 2.28; 95% CI, 1.13-4.61, P = 0.021 respectively). No effect was observed for the other tested biomarkers.

CONCLUSIONS

Elevated tissue expression of pERK and VEGFR-2 was predictive of poor outcome in advanced HCC treated with sorafenib.

Ribose-5-phosphate isomerase A regulates hepatocarcinogenesis via PP2A and ERK signaling

The deregulated nonoxidative pentose phosphate pathway (PPP) is known to promote oncogenesis, but the molecular mechanism remains unknown. Here, we report that human ribose-5-phosphate isomerase A (RPIA) plays a role in human hepatocellular carcinoma (HCC). A significant increase in RPIA expression was detected both in tumor biopsies of HCC patients and in a liver cancer tissue array. Importantly, the clinicopathological analysis indicated that RPIA mRNA levels were highly correlated with clinical stage, grade, tumor size, types, invasion and alpha-fetoprotein levels in the HCC patients. In addition, we demonstrated that the ability of RPIA to regulate cell proliferation and colony formation in different liver cancer cell lines required ERK signaling as well as the negative modulation of PP2A activity and that the effects of RPIA could be modulated by the addition of either a PP2A inhibitor or activator. Furthermore, the xenograft studies in nude mice revealed that the modulation of RPIA in liver cancer cells regulated tumor growth and that NIH3T3 cells overexpressing RPIA exhibited increased proliferation, enhanced colony formation, elevated levels of p-ERK1/2 and accelerated tumor growth. This study provides new insight into the molecular mechanisms by which RPIA overexpression can induce oncogenesis in HCC. Furthermore, it suggests that RPIA can be a good prognosis biomarker and a potential target for HCC therapy.

MEK 1/2 inhibitors in the treatment of hepatocellular carcinoma

Sorafenib is the only approved systemic treatment for advanced hepatocellular carcinoma patients and all the recently published randomized controlled trials on new systemic drugs have been unsuccessful. This is likely due to a lack of understanding of tumor progression, molecular drivers, and liver toxicity, as well as flaws in trial design. An important signaling pathway in hepatocarcinogenesis is the MEK cascade involved in various cellular responses, including adaptation and survival. A key role in this cascade is played by MEK, of which MEK 1/2 represent the prototypes and an interesting target for new oncological drugs. This review analyzes recent developments and future perspectives on the role of MEK inhibitors in hepatocellular carcinoma treatment.

The androgen receptor as an emerging target in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the male-dominant liver diseases with poor prognosis, although treatments for HCC have been progressing in the past decades. Androgen receptor (AR) is a member of the nuclear receptor superfamily. Previous studies reported that AR was expressed in human HCC and non-HCC tissues. AR is activated both ligand-dependently and ligand-independently. The latter is associated with a mitogen-activated protein kinase–, v-akt murine thymoma viral oncogene homolog 1–, or signal-transducer and activator of transcription–signaling pathway, which has been implicated in the development of HCC. It has been reported that more than 200 RNA expression levels are altered by androgen treatment. In the liver, androgen-responsive genes are cytochrome P450s, transforming growth factor β, vascular endothelial growth factor, and glucose-regulated protein 78 kDa, which are also associated with human hepatocarcinogenesis. Recent studies also revealed that AR plays a role in cell migration and metastasis. It is possible that cross-talk among AR-signaling, endoplasmic reticulum stress, and innate immune response is important for human hepatocarcinogenesis and HCC development. This review shows that AR could play a potential role in human HCC and represent one of the important target molecules for the treatment of HCC.

Disruption of a regulatory loop between DUSP1 and p53 contributes to hepatocellular carcinoma development and progression

BACKGROUND & AIMS

Altered expression of dual specificity phosphatase 1 (DUSP1) is common in tumors including hepatocellular carcinoma (HCC), and is predictive of tumor progression and poor prognosis. However, the tumor suppressive role of DUSP1 has yet to be clearly elucidated.

METHODS

The molecular mechanisms of tumor suppression that were investigated were induction of apoptosis, cell cycle inhibition, and regulation of p53. Additionally, the antitumor effect of DUSP1 was assessed using a mouse model. Associated signaling pathways in HCC cells and tissues were examined.

RESULTS

Downregulation of DUSP1 expression was significantly correlated with poor differentiation (p<0.001) and advanced HCC stage (p=0.023). DUSP1 expression resulted in HCC suppression and longer survival (p=0.0002) in a xenoplant mice model. DUSP1 inhibited p38 MAPK phosphorylation and subsequently suppressed HSP27 activation, resulting in enhanced p53 phosphorylation at sites S15, S20, and S46 in HCC cells. Enhanced p53 activation induced the expression of target genes p21 and p27, which are linked to cell cycle arrest and apoptosis. Thus, DUSP1 was potentially linked to p53 activation via the p38 MAPK/HSP27 pathway. Wild-type but not mutant p53 transcriptionally upregulated DUSP1 via its DNA-binding domain. DUSP1 and p53 might collaborate to suppress tumors in hepatocarcinogenesis via a positive regulatory loop.

CONCLUSIONS

Our results revealed that disruption of a positive regulatory loop between DUSP1 and p53 promoted HCC development and progression, providing a rationale for a therapeutic agent that restores DUSP1 in HCC.

The Ras/MAPK pathway and hepatocarcinoma: pathogenesis and therapeutic implications

BACKGROUND

Hepatocellular carcinoma (HCC) is still a major health problem, often diagnosed at an advanced stage. The multikinase inhibitor sorafenib is to date the sole approved systemic therapy. Several signalling pathways are implicated in tumour development and progression. Among these pathways, the Ras/MAPK pathway is activated in 50-100% of human HCCs and is correlated with a poor prognosis. The aim of this work was to review the main intracellular mechanisms leading to aberrant Ras pathway activation in HCC and the potential therapeutic implications.

MATERIALS AND METHODS

This review is based on the material found on PubMed up to December 2014. 'Ras signaling, Ras dysregulation, Ras inhibition, MAPK pathway, cancer, hepatocarcinoma and liver cancer' alone or in combination were the main terms used for online research.

RESULTS

Multiple mechanisms lead to the deregulation of the Ras pathway in liver cancer. Ras and Raf gene mutations are rare events in human hepatocarcinogenesis in contrast to experimental models in rodents. Downregulation of several Ras/MAPK pathway inhibitors such as GAPs, RASSF proteins, DUSP1, Sprouty and Spred proteins is largely implicated in the aberrant activation of this pathway in the context of wild-type Ras and Raf genes. Epigenetic or post-transcriptional mechanisms lead to the downregulation of these tumour suppressor genes.

CONCLUSION

Ras/MAPK pathway effectors may be considered as potential therapeutic targets in the field of HCC. In particular after the arrival of sorafenib, more Ras/MAPK inhibitors have emerged and are still in preclinical or clinical investigation for HCC therapy.

FAM83D activates the MEK/ERK signaling pathway and promotes cell proliferation in hepatocellular carcinoma

Publicly available microarray data suggests that the expression of FAM83D (Family with sequence similarity 83, member D) is elevated in a wide variety of tumor types, including hepatocellular carcinoma (HCC). However, its role in the pathogenesis of HCC has not been elucidated. Here, we showed that FAM83D was frequently up-regulated in HCC samples. Forced FAM83D expression in HCC cell lines significantly promoted their proliferation and colony formation while FAM83D knockdown resulted in the opposite effects. Mechanistic analyses indicated that FAM83D was able to activate the MEK/ERK signaling pathway and promote the entry into S phase of cell cycle progression. Taken together, these results demonstrate that FAM83D is a novel oncogene in HCC development and may constitute a potential therapeutic target in HCC.

Hydroxysafflor yellow A inhibits angiogenesis of hepatocellular carcinoma via blocking ERK/MAPK and NF-κB signaling pathway in H22 tumor-bearing mice

Hydroxysafflor yellow A (HSYA), a flavonoid derived and isolated from traditional Chinese medicine Carthamus tinctorius L., possesses anti-tumor activity. However, its effects on hepatocellular carcinoma (HCC) have not been investigated. The proliferation and metastasis of HCC are dependent on angiogenesis, which also strongly links with several signal transduction pathways associated with cell proliferation and apoptosis. This study aimed to explore the effect of HSYA on vasculogenesis and to determine its molecular mechanism by investigating the expression of ERK/MAPK (p-c-Raf, c-Raf, p-ERK1/2, ERK1/2) and NF-κB (p65, IκB and p-IκB) signaling pathway in H22 tumor-bearing mice. The results showed that HSYA could considerably suppress tumor growth by inhibiting secretion of angiogenesis factors (vascular endothelial growth factor A, basic fibroblast growth factor) and vascular endothelial growth factor receptor1. At the moleculcould block ERK1/2 phosphorylation and then restrain the activation of NF-κB and its nuclear translocation by down-regulating the expression of p65 in the nucleus, up-regulating p65 level in the cytoplasm, inhibiting IκB phosphorylation and cytoplasmic degradation of IκB-α. Finally, we demonstrate that HSYA could suppress mRNA expression levels of cell proliferation-related genes (cyclinD1, c-myc, c-Fos) compared with negative control group. And best of all, HSYA could improve spleen/thymus indexes, which was evaluated as the marker of protective effect on the immune system. Our findings support HSYA as a promising candidate for the prevention and treatment of HCC.

Prognostic values of ERK1/2 and p-ERK1/2 expressions for poor survival in non-small cell lung cancer

The extracellular-regulated kinase (ERK) 1/2, as a member of the mitogen-activated protein kinase family, plays a crucial role in the development of cancer. However, little is known about the prognostic value of ERK1/2 and phosphorylated ERK1/2 (p-ERK1/2) in non-small cell lung cancer (NSCLC). Thus, we investigated their prognostic values and analyzed the associations between their expressions and clinicopathological features in NSCLC patients. We examined ERK1/2 and p-ERK1/2 expressions via immunohistochemistry in 183 NSCLC samples. The prognostic significances of protein expression were evaluated with univariate and multivariate survival analysis. Of the specimens, 44.8 and 44.3 % revealed positive staining for ERK1/2 and p-ERK1/2, respectively. There were 24.6 % specimens with both ERK1/2 and p-ERK1/2-positive expression. The results showed p-ERK1/2-positive expression was an independent prognostic factor for poor overall survival (OS) in NSCLC patients on both univariate analysis (p < 0.0001) and multivariate analysis (p = 0.0000). Meanwhile, the positive expression of both proteins was also associated with poor OS (p = 0.002). With respect to clinicopathological features, the tumor differentiation was significantly associated with the positivity of ERK1/2, p-ERK1/2, and both proteins, while histological type was only related to ERK1/2. However, there were no significant differences between the expressions and other clinical features, such as gender, age, smoking, tumor-node-metastasis (TNM) stage, lymph node metastasis, and treatments. The p-ERK1/2-positive expression was associated with adverse outcomes, and the positive expression of both ERK1/2 and p-ERK1/2 proteins was also related to poor OS. Therefore, the positivity of p-ERK1/2 expression may serve as a vital biomarker in the development of NSCLC.

Selumetinib for the treatment of cancer

Introduction: The MAPK pathway is essential for regulation of cellular proliferation, differentiation and survival. Multiple human cancers have demonstrated activation of Raf-mitogen-activated kinase kinase (MEK)-extracellular signal-related kinase signaling, a hallmark of these tumors. Efforts to inhibit various protein kinases in this pathway have led to the development of MEK inhibitors. Selumetinib is one such drug, functioning as an oral, selective non-ATP-competitive MEK1/2 inhibitor. Areas covered: In this article, the authors discuss the underlying biology of MEK inhibition and its rationale in cancer treatment. Furthermore, the authors summarize the clinical development of selumetinib in various tumor types, from initial Phase I studies to randomized Phase II studies, both as monotherapy or in combination with other chemotherapeutics. Expert opinion: Given the frequency of activated MAPK signaling in multiple tumor types, the potent MEK inhibitor selumetinib had strong preclinical and early clinical rationale, particularly in those tumors harboring KRAS or BRAF mutations. While efficacy signals have been seen in various tumor types treated with selumetinib, better biomarkers are needed to select patients most likely to respond favorably to this agent. Furthermore, combinatorial therapy with selumetinib and other targeted agents can likely be optimized to maximize the antitumor effect of inhibiting RAS/MAPK signaling.

Oncogenic c-Myc and prothymosin-alpha protect hepatocellular carcinoma cells against sorafenib-induced apoptosis

Prothymosin alpha (PTMA) is overexpressed in various human tumors, including hepatocellular carcinoma (HCC). The significance of PTMA overexpression and its underlying mechanism remain unclear. We show here that silencing PTMA sensitizes HCC cells to the kinase inhibitor sorafenib. In contrast, ectopic expression of PTMA induces cell resistance to the drug. While inhibitors targeting JNK, ERK or PI3K reduce PTMA expression, only ERK activation is suppressed by sorafenib. In addition, inhibition of ERK produces a dramatic decrease in both endogenous PTMA level and promoter activation. Ectopic expression of active MKK1/2 considerably induces PTMA expression. We also identify a sorafenib-responsive segment lying 1000-1500-bp upstream of the PTMA transcription start site and observe that it is controlled by c-Myc and ERK. Mutation in the PTMA promoter at the predicted c-Myc binding site and silencing of c-Myc both abrogate sorafenib's effect on PTMA transcription. We also find that silencing PTMA potentiates Bax translocation to mitochondria in response to sorafenib and this is associated with increased cytochrome c release from mitochondria and enhanced caspase-9 activation. These results indicate that PTMA is positively regulated by the oncoprotein c-Myc and protects HCC cells against sorafenib-induced cell death, thus identifying PTMA as a new target for chemotherapy against HCC.

Preserving hepatic artery flow during portal triad blood inflow occlusion reduces the outgrowth of hepatocarcinoma in mice after ischemia-reperfusion

AIM

To investigate the effect of different hepatic vascular occlusion maneuvers on the growth of hepatocarcinoma after liver ischemia-reperfusion (I/R) injury.

METHODS

A mice hepatocarcinoma model was established by portal vein injection of H22 hepatoma cells. After 3 days, the mice underwent sham operation, occlusion of portal triad (OPT), portal vein (OPV), or intermittent clamping (INT) operation. The hepatic I/R injury, pathological changes, hepatic replacement area, proliferative cell nuclear antigen expression, and extracellular signal-regulated kinase (ERK) 1/2 activation were assessed 5 days after reperfusion.

RESULTS

Alanine aminotransferase and aspartate aminotransferase levels in the OPV group were significantly lower than those in the OPT and INT groups at 24 h after reperfusion. The hepatic injury of clamped liver lobes in the OPV group, represented by histopathological alterations and myeloperoxidase activity, was much slighter than that in the OPT and INT groups. The values of hepatic replacement area in the sham operation, OPT, OPV, and INT groups were 7.661 2.55%, 35.61 1 4.23%, 9.02 1 3.01%, and 19.95 1 4.10%, respectively. Proliferative cell nuclear antigen expression and ERK1/2 activation of tumor cells were the highest in the OPT group, and the lowest in the OPV and INT groups.

CONCLUSION

Preserving hepatic artery flow during portal triad blood inflow occlusion substantially inhibits the outgrowth of hepatocarcinoma via attenuating hepatic I/R injury in a murine liver tumor model. These results suggest a better prevention of hepatic tumor outgrowth after hepatectomy by using the selective portal vein clamping method in liver cancer patients.

Allosteric MEK1/2 inhibitor refametinib (BAY 86-9766) in combination with sorafenib exhibits antitumor activity in preclinical murine and rat models of hepatocellular carcinoma

OBJECTIVE

The objectives of the study were to evaluate the allosteric mitogen-activated protein kinase kinase (MEK) inhibitor BAY 86-9766 in monotherapy and in combination with sorafenib in orthotopic and subcutaneous hepatocellular carcinoma (HCC) models with different underlying etiologies in two species.

DESIGN

Antiproliferative potential of BAY 86-9766 and synergistic effects with sorafenib were studied in several HCC cell lines. Relevant pathway signaling was studied in MH3924a cells. For in vivo testing, the HCC cells were implanted subcutaneously or orthotopically. Survival and mode of action (MoA) were analyzed.

RESULTS

BAY 86-9766 exhibited potent antiproliferative activity in HCC cell lines with half-maximal inhibitory concentration values ranging from 33 to 762 nM. BAY 86-9766 was strongly synergistic with sorafenib in suppressing tumor cell proliferation and inhibiting phosphorylation of the extracellular signal-regulated kinase (ERK). BAY 86-9766 prolonged survival in Hep3B xenografts, murine Hepa129 allografts, and MH3924A rat allografts. Additionally, tumor growth, ascites formation, and serum alpha-fetoprotein levels were reduced. Synergistic effects in combination with sorafenib were shown in Huh-7, Hep3B xenografts, and MH3924A allografts. On the signaling pathway level, the combination of BAY 86-9766 and sorafenib led to inhibition of the upregulatory feedback loop toward MEK phosphorylation observed after BAY 86-9766 monotreatment. With regard to the underlying MoA, inhibition of ERK phosphorylation, tumor cell proliferation, and microvessel density was observed in vivo.

CONCLUSION

BAY 86-9766 shows potent single-agent antitumor activity and acts synergistically in combination with sorafenib in preclinical HCC models. These results support the ongoing clinical development of BAY 86-9766 and sorafenib in advanced HCC.

Long non-coding RNA URHC regulates cell proliferation and apoptosis via ZAK through the ERK/MAPK signaling pathway in hepatocellular carcinoma

Long non-coding RNAs (lncRNAs) have previously been implicated in human disease states, especially cancer. Although the aberrant expression of lncRNAs has been observed in cancer, the biological functions and molecular mechanisms underlying aberrantly expressed lncRNAs in hepatocellular carcinoma (HCC) have not been widely established. In the present study, we investigated a novel lncRNA, termed URHC (up-regulated in hepatocellular carcinoma), and evaluated its role in the progression of HCC. Expression profiling using a lncRNA microarray revealed that URHC was highly expressed in 3 HCC cell lines compared to normal hepatocytes. Quantitative real-time polymerase chain reaction (qRT-PCR) analyses confirmed that URHC expression was increased in hepatoma cells and HCC tissues. Moreover, using qRT-PCR, we confirmed that URHC expression was up-regulated in 30 HCC cases (57.7%) and that its higher expression was correlated with poor overall survival. We further demonstrated that URHC inhibition reduced cell proliferation and promoted apoptosis. We hypothesize that URHC may function by regulating the sterile alpha motif and leucine zipper containing kinase AZK (ZAK) gene, which is located near URHC on the same chromosome. We found that ZAK mRNA levels were down-regulated in HCC tissues and the expression levels of ZAK were negatively correlated with those of URHC in the above HCC tissues. Next, we confirmed that URHC down-regulated ZAK, which is involved in URHC-mediated cell proliferation and apoptosis. Furthermore, ERK/MAPK pathway inactivation partially accounted for URHC-ZAK-induced cell growth and apoptosis. Thus, we concluded that high URHC expression can promote cell proliferation and inhibit apoptosis by repressing ZAK expression through inactivation of the ERK/MAPK pathway. These findings may provide a novel mechanism and therapeutic targets for the treatment of HCC.

Multidisciplinary management of hepatocellular carcinoma in clinical practice

Background. Hepatocellular carcinoma (HCC) patients require different treatment strategies according to disease extension, liver function, and patient's fitness. We evaluated HCC multidisciplinary management in clinical practice. Methods. Consecutive patients were followed and treated with tailored medical, locoregional, and surgical treatments, according to disease stage and patient's fitness (age, Cumulative Illness Rating Scale (CIRS)). Activity, efficacy, and safety were evaluated. Results. Thirty-eight patients were evaluated: median age, 74; elderly 92%; CIRS secondary 28 (74%); Child-Pugh A 20 (53%), B 11 (29%); and Barcelona Clinic Liver Cancer (BCLC) 0 2 (5%), A 9 (24%), B 10 (26%), C 13 (34%), and D 4 (11%). Overall survival (OS) was 30 months. At 9 months median follow-up, among 25 unresectable HCC, OS was 10 months; BCLC B–D unfit for sorafenib showed OS 3 months. Ten patients (40%) received sorafenib: Child-Pugh A 5 (50%) and B 5 (50%) and disease control rate 89%, progression-free survival 7 months, and OS 9 months. G3-4 toxicities: anorexia, hypertransaminaemia, hyperbilirubinemia, and hypercreatininemia. Limiting toxicity syndromes were 40%, all multiple sites. Conclusion. HCC patients require multidisciplinary clinical management to properly select tailored treatments according to disease stage, fitness, and liver function. Patients suitable for sorafenib should be carefully selected, monitored for individual safety, and prevalently characterized by limiting toxicity syndromes multiple sites.

The combination of rapamycin and MAPK inhibitors enhances the growth inhibitory effect on Nara-H cells

The inhibition of the mammalian target of rapamycin (mTOR) signaling pathway promotes the initiation of autophagy, and the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated protein kinase (ERK) is well known to induce autophagy. Autophagy is a self-defense mechanism of cancer cells that are subjected to antitumor agents, and blocking autophagy can trigger apoptosis. In the present study, we demonstrate that an mTOR inhibitor, rapamycin, induces autophagy in the Nara-H malignant fibrous histiocytoma (MFH) cell line through the activation of ERK1/2. Rapamycin-induced apoptosis was enhanced following the inhibition of the MEK/ERK pathway. In the Nara-H cells, we examined the effects of rapamycin treatment on cell proliferation and on the phosphorylation of the mTOR pathway components and autophagy by western blot analysis. Furthermore, we examined the effects of rapamycin with or without the MEK inhibitor, U0126, on the induction of apoptosis by using fluorescence microscopy. Rapamycin inhibited Nara-H cell proliferation and decreased the phosphorylation of the mTOR pathway in the Nara-H cells. Rapamycin induced the apoptosis of Nara-H cells, and this apoptosis was enhanced by U0126. Simultaneously, phospho-ERK1/2 was activated by rapamycin. The present study demonstrates that rapamycin induces autophagy in Nara-H cells by activating the MEK/ERK signaling pathway, and the rapamycin-induced apoptosis can be enhanced by the MEK inhibitor, U0126. These results suggest that self-protective mechanisms involving mTOR inhibitors in Nara-H cells are prevented by the inhibition of the MEK/ERK pathway. The combination of an mTOR inhibitor (e.g., rapamycin) and an MEK inhibitor (e.g., U0126) may offer effective treatment for MFH, as this combination effectively activates apoptotic pathways.

Sorafenib for the treatment of hepatocellular carcinoma across geographic regions

Sorafenib is an oral multikinase inhibitor targeting Raf, VEGF receptor, PDGF receptor, c-kit, Flt-3 and rearranged during transfection (RET). Two randomized, placebo-controlled trials for Western and Asian patients, respectively, demonstrated that sorafenib significantly prolongs overall survival and time to progression in patients with advanced hepatocellular carcinoma (HCC). These have become the reference treatment for future clinical trials of advanced HCC. Sorafenib is well tolerated in patients with Child-Pugh liver function class A, but limited data are available in Child-Pugh class B and C patients. Clinical trials are ongoing to test the efficacy of sorafenib-based combination therapy and sorafenib adjuvant therapy for HCC.

The Complex Relationship between Liver Cancer and the Cell Cycle: A Story of Multiple Regulations

The liver acts as a hub for metabolic reactions to keep a homeostatic balance during development and growth. The process of liver cancer development, although poorly understood, is related to different etiologic factors like toxins, alcohol, or viral infection. At the molecular level, liver cancer is characterized by a disruption of cell cycle regulation through many molecular mechanisms. In this review, we focus on the mechanisms underlying the lack of regulation of the cell cycle during liver cancer, focusing mainly on hepatocellular carcinoma (HCC). We also provide a brief summary of novel therapies connected to cell cycle regulation.

Identification of SLAMF3 (CD229) as an inhibitor of hepatocellular carcinoma cell proliferation and tumour progression

Although hepatocellular carcinoma (HCC) is one of the most common malignancies and constitutes the third leading cause of cancer-related deaths, the underlying molecular mechanisms are not fully understood. In the present study, we demonstrate for the first time that hepatocytes express signalling lymphocytic activation molecule family member 3 (SLAMF3/CD229) but not other SLAMF members. We provide evidence to show that SLAMF3 is involved in the control of hepatocyte proliferation and in hepatocellular carcinogenesis. SLAMF3 expression is significantly lower in primary human HCC samples and HCC cell lines than in human healthy primary hepatocytes. In HCC cell lines, the restoration of high levels of SLAMF3 expression inhibited cell proliferation and migration and enhanced apoptosis. Furthermore, SLAMF3 expression was associated with inhibition of HCC xenograft progression in the nude mouse model. The restoration of SLAMF3 expression levels also decreased the phosphorylation of MAPK ERK1/2, JNK and mTOR. In samples from resected HCC patients, SLAMF3 expression levels were significantly lower in tumorous tissues than in peritumoral tissues. Our results identify SLAMF3 as a specific marker of normal hepatocytes and provide evidence for its potential role in the control of proliferation of HCC cells.

[Current status of molecular targeted therapies in hepatocellular carcinoma]

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer death in Korea. Curative treatment is only possible when the disease is diagnosed at the early stage. The prognosis of patients with HCC is even dismal in advanced stages. No systemic cytotoxic chemotherapy has proven to be beneficial in overall survival. Recently, the understanding of the molecular pathogenesis led to the development of new therapies. With the evidence of dysregulation of critical genes associated with cellular proliferation, growth factor signaling, cell cycling, apoptosis, and angiogenesis in HCC, a number of molecular target agents are under clinical trials. Sorafenib is the first systemic anticancer drug which has proven to gain survival benefit in the global as well as Asia-Pacific trials. However, the survival gain is still modest, and further efforts to improve outcomes in patients with HCC are necessary by developing novel drugs or combining other forms of therapies. This article will review signaling pathways in HCC and introduce molecular target agents under investigation currently.

Crosstalk between beta-catenin and snail in the induction of epithelial to mesenchymal transition in hepatocarcinoma: role of the ERK1/2 pathway

Epithelial to mesenchymal transition (EMT) is an integral process in the progression of many epithelial tumors. It involves a coordinated series of events, leading to the loss of epithelial features and the acquisition of a mesenchymal phenotype, resulting in invasion and metastasis. The EMT of hepatocellular carcinoma (HCC) cells is thought to be a key event in intrahepatic dissemination and distal metastasis. In this study, we used 12-O-tet-radecanoylphorbol-13-acetate (TPA) to dissect the signaling pathways involved in the EMT of HepG2 hepatocarcinoma cells. The spectacular change in phenotype induced by TPA, leading to a pronounced spindle-shaped fibroblast-like cell morphology, required ERK1/2 activation. This ERK1/2-dependent EMT process was characterized by a loss of E-cadherin function, modification of the cytoskeleton, the acquisition of mesenchymal markers and profound changes to extracellular matrix composition and mobility. Snail was essential for E-cadherin repression, but was not sufficient for full commitment of the TPA-triggered EMT. We found that TPA triggered the formation of a complex between Snail and β-catenin that activated the Wnt pathway. This study thus provides the first evidence for the existence of a complex network governed by the ERK1/2 signaling pathway, converging on the coregulation of Snail and the Wnt/β-catenin pathway and responsible for the onset and the progression of EMT in hepatocellular carcinoma cells.

MEK in cancer and cancer therapy

The mitogen-activated extracellular signal-regulated kinase (MEK) pathway is one of the best-characterized kinase cascades in cancer cell biology. It is triggered by either growth factors or activating mutations of major oncogenic proteins in this pathway, the most common being Ras and Raf. Deregulation of this pathway is frequently observed and plays a central role in the carcinogenesis and maintenance of several cancers, including melanoma, pancreatic, lung, colorectal, and breast cancers. Targeting these kinases offers promise of novel therapies. MEK inhibitors (MEKi) are currently under evaluation in clinical trials and many have shown activity. In this review, we comprehensively examine the role of the MEK pathway in carcinogenesis and its therapeutic potential in cancer patients, with a focus on MEKi. We describe the clinical perspectives of MEKi in the two main models of Ras-ERK driven tumors, BRAF-mutant ("addicted" to the pathway) and KRAS-mutant (non-"addicted"). We also highlight the known mechanisms of resistance to MEKi and emerging strategies to overcome it.

Molecular targeted therapy for hepatocellular carcinoma: current and future

Hepatocellular carcinoma (HCC) is one of the most frequent tumors worldwide. The majority of HCC cases occur in patients with chronic liver disease. Despite regular surveillance to detect small HCC in these patients, HCC is often diagnosed at an advanced stage. Because HCC is highly resistant to conventional systemic therapies, the prognosis for advanced HCC patients remains poor. The introduction of sorafenib as the standard systemic therapy has unveiled a new direction for future research regarding HCC treatment. However, given the limited efficacy of the drug, a need exists to look beyond sorafenib. Many molecular targeted agents that inhibit different pathways involved in hepatocarcinogenesis are under various phases of clinical development, and novel targets are being assessed in HCC. This review aims to summarize the efforts to target molecular components of the signaling pathways that are responsible for the development and progression of HCC and to discuss perspectives on the future direction of research.

Sunitinib versus sorafenib in advanced hepatocellular cancer: results of a randomized phase III trial

PURPOSE

Open-label, phase III trial evaluating whether sunitinib was superior or equivalent to sorafenib in hepatocellular cancer.

PATIENTS AND METHODS

Patients were stratified and randomly assigned to receive sunitinib 37.5 mg once per day or sorafenib 400 mg twice per day. Primary end point was overall survival (OS).

RESULTS

Early trial termination occurred for futility and safety reasons. A total of 1,074 patients were randomly assigned to the study (sunitinib arm, n = 530; sorafenib arm, n = 544). For sunitinib and sorafenib, respectively, median OS was 7.9 versus 10.2 months (hazard ratio [HR], 1.30; one-sided P = .9990; two-sided P = .0014); median progression-free survival (PFS; 3.6 v 3.0 months; HR, 1.13; one-sided P = .8785; two-sided P = .2286) and time to progression (TTP; 4.1 v 3.8 months; HR, 1.13; one-sided P = .8312; two-sided P = .3082) were comparable. Median OS was similar among Asian (7.7 v 8.8 months; HR, 1.21; one-sided P = .9829) and hepatitis B-infected patients (7.6 v 8.0 months; HR, 1.10; one-sided P = .8286), but was shorter with sunitinib in hepatitis C-infected patients (9.2 v 17.6 months; HR, 1.52; one-sided P = .9835). Sunitinib was associated with more frequent and severe adverse events (AEs) than sorafenib. Common grade 3/4 AEs were thrombocytopenia (29.7%) and neutropenia (25.7%) for sunitinib; hand-foot syndrome (21.2%) for sorafenib. Discontinuations owing to AEs were similar (sunitinib, 13.3%; sorafenib, 12.7%).

CONCLUSION

OS with sunitinib was not superior or equivalent but was significantly inferior to sorafenib. OS was comparable in Asian and hepatitis B-infected patients. OS was superior in hepatitis C-infected patients who received sorafenib. Sunitinib-treated patients reported more frequent and severe toxicity.

Signal transduction disturbance related to hepatocarcinogenesis in mouse by prolonged exposure to Nanjing drinking water

Toxicogenomic approaches were used to investigate the potential hepatocarcinogenic effects on mice by oral exposure to Nanjing drinking water (NJDW). Changes in the hepatic transcriptome of 3 weeks male mice (Mus musculus) were monitored and dissected after oral exposure to NJDW for 90 days. No preneoplastic and neoplastic lesions were observed in the hepatic tissue by the end of NJDW exposure. However, total of 746 genes were changed transcriptionally. Thirty-one percent of differentially expressed genes (DEGs) were associated with the functional categories of cell cycle regulation, adhesion, growth, apoptosis, and signal transduction, which are closely implicated in tumorigenesis and progression. Interrogation of Kyoto Encyclopedia of Genes and Genomes revealed that 43 DEGs were mapped to several crucial signaling pathways implicated in the pathogenesis of hepatocellular carcinoma (HCC). In signal transduction network constructed via Genes2Networks software, Egfr, Akt1, Atf2, Ctnnb1, Hras, Mapk1, Smad2, and Ccnd1 were hubs. Direct gene-disease relationships obtained from Comparative Toxicogenomics Database and scientific literatures revealed that the hubs have direct mechanism or biomarker relationships with hepatocellular preneoplastic lesions or hepatocarcinogenesis. Therefore, prolonged intake of NJDW without employing any indoor water treatment strategy might predispose mouse to HCC. Furthermore, Egfr, Akt1, Ctnnb1, Hras, Mapk1, Smad2, and Ccnd1 were identified as promising biomarkers of the potential combined hepatocarcinogenicity.

Feasibility of sorafenib combined with local radiotherapy in advanced hepatocellular carcinoma

PURPOSE

Sorafenib is an effective systemic agent for advanced hepatocellular carcinoma. To increase its efficacy, we evaluated the feasibility and benefit of sorafenib combined with radiotherapy.

MATERIALS AND METHODS

From July 2007 to July 2011, 31 patients were treated with a daily dose of 800 mg of sorafenib and radiotherapy. Among them, 13 patients who received radiotherapy on the bone metastasis were excluded. Thirteen patients received 30-54 Gy of radiotherapy on the primary tumor (primary group) and 5 patients received 30-58.4 Gy on the measurable metastatic lesions (measurable metastasis group). Tumor responses at 1 month after the completion of radiotherapy and overall survival were evaluated.

RESULTS

The in-field response rate was 100% in the primary group and 60% in the measurable metastasis group. A decrease of more than 80% in the tumor marker α-fetoprotein was observed in 7 patients in the primary group (54%). Toxicities of grades 3-4 were hand-foot syndrome in 3 (17%) patients, duodenal bleeding in 1 (6%) patient, thrombocytopenia in 3 (17%) patients and elevation of aspartate transaminase in 1 (6%) patient. The median overall survival was 7.8 months (95% confidence interval, 3.0-12.6).

CONCLUSION

The combined treatment of sorafenib and radiotherapy was feasible and induced substantial tumor responses in the target lesions. The results of this study emphasize the importance of individualized approach in the management of advanced hepatocellular carcinoma and encourage the initiation of a controlled clinical trial.

Targeting therapy of hepatocellular carcinoma with doxorubicin prodrug PDOX increases anti-metastatic effect and reduces toxicity: a preclinical study

BACKGROUND

This study was to investigate the effects and safety of cathepsin B-cleavable doxorubicin (DOX)-prodrug (PDOX) for targeting therapy of metastatic human hepatocellular carcinoma (HCC) using DOX as a positive control drug.

METHODS

The orthotopic nude mice model of highly metastatic HCC was established and the animals were randomized and treated with PDOX, DOX and saline, respectively. Hematology, biochemistry and tumor markers were studied. At autopsy, liver tumor weight and size, ascites, abdominal lymph nodes metastases, experimental peritoneal carcinomatosis index (ePCI), and tumor-host body weight ratio were investigated. Immunohistochemical studies and western blotting were done to investigate key molecules involved in the mechanism of action.

RESULTS

Compared with Control, both PDOX and DOX could similarly and significantly reduce liver tumor weight and tumor volume by over 40%, ePCI values, retroperitoneal lymph node metastases and lung metastases and serum AFP levels (P < 0.05). The PDOX group had significantly higher WBC than the DOX group (P < 0.05), and higher PLT than Control (P < 0.05). Serum BUN and Cr levels were lower in the PDOX group than DOX and Control groups (P < 0.05). Compared with Control, DOX increased CK and CK-MB; while PDOX decreased CK compared with DOX (P < 0.05). Multiple spotty degenerative changes of the myocardium were observed in DOX-treated mice, but not in the Control and PDOX groups. PDOX could significantly reduce the Ki-67 positive rate of tumor cells, compared with DOX and Control groups. PDOX produced the effects at least via the ERK pathway.

CONCLUSION

Compared with DOX, PDOX may have better anti-metastatic efficacy and reduced side effects especially cardio-toxicities in this HCC model.

Sorafenib in combination with transarterial chemoembolization in Chinese patients with hepatocellular carcinoma: a subgroup interim analysis of the START trial

AIM

The third interim results of the START trial showed encouraging safety and efficacy profiles, with a median time to progression of 9 months. This subgroup analysis presents results in Chinese patients enrolled in the START trial.

MATERIALS & METHODS

Sixty two Chinese patients (median age 52 years) with unresectable hepatocellular carcinoma had transarterial chemoembolization (TACE) performed with an emulsion of Lipiodol(®) (Guerbet, Paris, France) and doxorubicin (30-60 mg) followed by embolization with absorbable particles. Sorafenib (400 mg twice-daily) was administered continuously with dose holidays 4 days prior to and post TACE procedures. TACE was performed every 6-8 weeks and responses were assessed after 4-6 weeks and then every 3 months if no further TACE was indicated. Patients continued receiving sorafenib until disease progression or unacceptable toxicity occurred.

RESULTS

Thirty seven patients (59.68%) received no more than two TACE procedures. During sorafenib treatment (median duration 6.4 months; mean daily dose 787.6 mg), 75.8% of patients experienced adverse events, most commonly pyrexia (37.1%), diarrhea (27.4%), skin reactions (22.6%), alopecia (19.4%) and abnormal hepatic function (16.1%). The most common grade 3-4 adverse events were abnormal hepatic function (6.5%) and diarrhea (3.2%). The median time to progression and overall survival were 10.6 and 16.5 months, respectively, and the objective response and stable disease rates were 44.3 and 42.6%, respectively.

CONCLUSION

The combination of the TACE and sorafenib proved both safe and effective in the treatment of Chinese patients with unresectable hepatocellular carcinoma.

MEK inhibition induced downregulation of MRP1 and MRP3 expression in experimental hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) exhibits strong intrinsic and acquired drug resistance which is the main obstacle to chemotherapy. Overexpression of ATP binding cassette (ABC) proteins correlates with activation of mitogen activated protein kinase (MAPK) pathway in HCC. Here, we systematically investigated the inhibition of MAPK pathway and its role in regulating HCC cell growth as well as ABC proteins MRP1 and MRP3 expression.

METHODS

The Raf1 kinase inhibitor (GW5074) and different MEK inhibitors (U0126 and AZD6244) were used to treat HCC cells to identify their effects on HCC cell growth and ABC proteins expression in vitro. Cell viability tests were performed after the treatment of MAPK pathway inhibitors and in combination with gemcitabine or doxorubicin. Western blot was applied to assess the changes of MAPK pathway and protein expression of MRP1 and MRP3. Flow cytometry was used to measure intracellular doxorubicin accumulation after the treatment of MEK inhibitors.

RESULTS

Both Raf1 inhibitor (GW5074) and MEK inhibitors (U0126 and AZD6244) suppressed HCC cell growth in a dose dependent manner. Pre-treatment of MEK inhibitor U0126 or AZD6244 sensitized HCC cells to gemcitabine or doxorubicin based chemotherapy. Raf1 inhibitor GW5074 had no effect on MRP1 and MRP3 protein expression. Treatment of gemcitabine or doxorubicin activated phosphorylated ERK and induced the upregulation of MRP1 and MRP3. MEK inhibitors U0126 and AZD6244 deactivated phosphorylated ERK, decreased endogenous MRP1 expression, reversed gemcitabine or doxorubicin induced MRP1 and MRP3 upregulation, and increased the intracellular doxorubicin accumulation.

CONCLUSION

This study provides evidence that MEK inhibitors sensitize HCC cells to chemotherapy by increasing intracellular chemodrug accumulation. MEK inhibirors U0126 and AZD6244 reduced MRP1 as well as MRP3 expression, and may contribute partially to the sensitization. The combination of MEK inhibitor and conventional chemotherapy may offer new therapeutic option for the treatment of resistant HCC.

Hepatitis B virus regulation of Raf1 promoter activity through activation of transcription factor AP-2α

The X protein of hepatitis B virus (HBx) is one of the important factors in the development of hepatocellular carcinoma. Raf1 kinase is a central component of many signaling pathways that are involved in normal cell growth and oncogenic transformation. We previously demonstrated that hepatitis B virus regulates Raf1 expression in HepG2.2.15 cells by enhancing its promoter activity and that HBx and HBs might play an important role in this process. However, the underlying molecular mechanisms remain unclear. In this study, we show that nucleotides -209 to -133 of the Raf1 promoter sequence constitute the core region where hepatitis B virus is regulated. This regulation was found to require the involvement of cis-regulatory element AP-2α. We further demonstrated that AP-2α expression was higher in HepG2.2.15 cells (HBV-expressing cells) than in HepG2 cells in vitro. Silencing AP-2α expression by siRNA significantly inhibited the Raf1 promoter activity in HepG2.2.15 cells. These findings indicated that HBV regulates Raf1 promoter activity, possibly through AP-2α.

DBC1 does not function as a negative regulator of SIRT1 in liver cancer

The putative tumor suppressor, DBC1 (deleted in breast cancer-1), was recently found to negatively regulate SIRT1 in vitro and in vivo, but the mechanism whereby DBC1 regulates SIRT1 in liver cancer remains to be elucidated. In this study, it was found that although the expression of DBC1 and SIRT1 was not aberrantly regulated in a large cohort of human hepatocellular carcinoma (HCC) patients, these proteins were highly overexpressed in a subset of HCC tissues compared with surrounding non-cancer tissues. In liver cancer, DBC1 and SIRT1 were found to be positively correlated. Inactivation of DBC1 or SIRT1 reduced SNU-182 (a liver cancer cell line) proliferation as determined by MTT viability assays. Notably, although DBC1 functions as a negative regulator of SIRT1 in A549 lung cancer cells since it suppresses the deacetylase activity of the p53 protein, it did not affect the p53 deacetylase activity of SIRT1 in SNU-182 cells. Taken together, we conclude that DBC1 is associated with SIRT1 in HCC, but that it does not inhibit SIRT1.

Modeling of tumor progression in NSCLC and intrinsic resistance to TKI in loss of PTEN expression

EGFR signaling plays a very important role in NSCLC. It activates Ras/ERK, PI3K/Akt and STAT activation pathways. These are the main pathways for cell proliferation and survival. We have developed two mathematical models to relate to the different EGFR signaling in NSCLC and normal cells in the presence or absence of EGFR and PTEN mutations. The dynamics of downstream signaling pathways vary in the disease state and activation of some factors can be indicative of drug resistance. Our simulation denotes the effect of EGFR mutations and increased expression of certain factors in NSCLC EGFR signaling on each of the three pathways where levels of pERK, pSTAT and pAkt are increased. Over activation of ERK, Akt and STAT3 which are the main cell proliferation and survival factors act as promoting factors for tumor progression in NSCLC. In case of loss of PTEN, Akt activity level is considerably increased. Our simulation results show that in the presence of erlotinib, downstream factors i.e. pAkt, pSTAT3 and pERK are inhibited. However, in case of loss of PTEN expression in the presence of erlotinib, pAkt level would not decrease which demonstrates that these cells are resistant to erlotinib.

Expression of serotonin receptors in human hepatocellular cancer

PURPOSE

Serotonin is a well-known neurotransmitter and vasoactive substance. Recent research indicates that serotonin contributes to liver regeneration and promotes tumor growth of human hepatocellular cancer. The aim of this study is to investigate the expression of serotonin receptors in hepatocellular cancer and analyze their potential as a cytotoxic target.

EXPERIMENTAL DESIGN

Using a tissue microarray and immunohistochemistry, we analyzed the expression of serotonin receptors in the liver from 176 patients with hepatocellular carcinoma, of which nontumor tissue was available in 109 patients. Relevant clinicopathologic parameters were compared with serotonin receptor expression. Two human hepatocellular cancer cell lines, Huh7 and HepG2, were used to test serotonin antagonists as a possible cytotoxic drug.

RESULTS

The serotonin receptors 1B and 2B were expressed, respectively, in 32% and 35% of the patients with hepatocellular cancer. Both receptors were associated with an increased proliferation index, and receptor 1B correlated with the size of the tumor. Serotonin antagonists of receptors 1B and 2B consistently decreased viability and proliferation in Huh7 and HepG2 cell lines.

CONCLUSION

We identified two serotonin receptors that are often overexpressed in human hepatocellular cancer and may serve as a new cytotoxic target.

Chemotherapy agents: a primer for the interventional radiologist

In this article, the authors review the basic principles of cancer chemotherapy and provide an overview of each of the general classes of chemotherapeutic agents with a target audience of interventional radiologists in mind. Special attention is paid to agents used in regional chemotherapy as well as agents commonly included in systemic chemotherapeutic regimens for patients who also require regional chemotherapy.