Novel concepts in hepatocellular carcinoma: from molecular research to clinical practice

The Prognostic Value of the Albumin to Gamma-Glutamyltransferase Ratio in Patients with Hepatocellular Carcinoma Undergoing Radiofrequency Ablation

Albumin to gamma-glutamyltransferase ratio (AGR) is a newly developed biomarker for the prediction of patients' prognosis in solid tumors. The purpose of the study was to establish a novel AGR-based nomogram to predict tumor prognosis in patients with early-stage HCC undergoing radiofrequency ablation (RFA). 394 hepatocellular carcinoma (HCC) patients who had received RFA as initial treatment were classified into the training cohort and validation cohort. Independent prognostic factors were identified by univariate and multivariate analyses. The value of AGR was evaluated by the concordance index (C-index), receiver operating characteristic (ROC) curves, and likelihood ratio tests (LAT). Logistic regression and nomogram were performed to establish the pretreatment scoring model based on the clinical variables. As a result, AGR = 0.63 was identified as the best cutoff value to predict overall survival (OS) in the training cohort. According to the results of multivariate analysis, AGR was an independent indicator for OS and recurrence-free survival (RFS). In both training cohort and validation cohort, the high-AGR group showed better RFS and OS than the low-AGR group. What is more, the C-index, area under the ROC curves, and LAT χ 2 values suggested that AGR outperformed the Child-Pugh (CP) grade and albumin-bilirubin (ALBI) grade in terms of predicting OS. The AGR, AKP, and tumor size were used to establish the OS nomogram. Besides, the results of Hosmer-Lemeshow test and calibration curve analysis displayed that both nomograms in the training and validation cohorts performed well in terms of calibration. Therefore, the AGR-based nomogram can predict the postoperative prognosis of early HCC patients undergoing RFA.

Long non‑coding RNAs in HBV‑related hepatocellular carcinoma (Review)

Hepatitis B virus (HBV)‑related hepatocellular carcinoma (HCC) is a global health problem that accounts for more than half of total liver cancer cases in developing countries. Despite the growing number of researches conducted, the molecular mechanism underlying the development of HCC remains elusive. Long non‑coding RNAs (lncRNAs), which are non‑coding RNAs >200 nt in length that were previously considered to be transcriptional noise, have been found to be dysregulated in HBV‑related HCC with the help of high‑throughput omics techniques. Subsequent investigations revealed that aberrant expression of lncRNAs may affect the risk of HBV‑related HCC through diverse mechanisms, including epigenetic silencing of transcriptional activation, alternative splicing, molecular sponging, modulating protein stability, and by serving as precursors of miRNAs. Although the sensitivity and specificity of lncRNAs must be further validated, a number of circulating lncRNAs have been identified as useful biomarkers for HBV‑related HCC. In addition to these findings, recent studies also unveiled that certain genetic polymorphisms in lncRNAs may affect the occurrence and prognosis of HBV‑related HCC. The aim of the present review was to provide an overview of the mechanisms underlying the involvement of lncRNAs in HBV‑related HCC. Subsequently, lncRNAs found to be dysregulated in HBV‑related HCC were focused on and current findings on circulating lncRNAs and their genetic polymorphisms were discussed.

Protein phosphatase magnesium-dependent 1δ is a novel tumor marker and target in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a lethal liver malignancy worldwide. In this study, we reported that protein phosphatase magnesium-dependent 1δ (PPM1D) was highly expressed in the majority of HCC cases (approximately 59%) and significantly associated with high serum α-fetoprotein (AFP) level (P = 0.044). Kaplan- Meier and Cox regression data indicated that PPM1D overexpression was an independent predictor of HCCspecific overall survival (HR, 2.799; 95% CI, 1.346-5.818, P = 0.006). Overexpressing PPM1D promoted cell viability and invasion, whereas RNA interference-mediated knockdown of PPM1D inhibited proliferation, invasion, and migration of cultured HCC cells. In addition, PPM1D suppression by small interfering RNA decreased the tumorigenicity of HCC cells in vivo. Overall, results suggest that PPM1D is a potential prognostic marker and therapeutic target for HCC.

DJ-1 knockdown inhibits growth and xenograft‑induced tumor generation of human hepatocellular carcinoma cells

The aim of this study was to identify potential downstream effectors of the oncogene DJ-1 in hepatocellular carcinoma (HCC) cell lines, and examine its role in the Akt signaling pathway and HCC oncogenesis. Expression of the DJ-1 protein was assessed by immunoblotting in several human HCC cell lines. Knockdown of DJ-1 was achieved by transfecting DJ-1-specific short hairpin RNAs into the HepG2 HCC cell line. The effect of DJ-1 downregulation on phosphatase and tensin homolog (PTEN) and phosphorylated Akt was evaluated. In addition, cell cycle, proliferation, adhesion and invasion were analyzed in the DJ-1 knockdown of HepG2 cells. The growth of HepG2‑induced tumor was evaluated in a nude mouse model after DJ-1 silencing. Stable DJ-1 knockdown was achieved in HepG2 cells using a shRNA eukaryotic expression vector. Downregulation of DJ-1 increased PTEN expression but decreased phosphorylation of Akt in HepG2 cells. In addition, DJ-1 knockdown resulted in the decreased proliferation, adhesion and invasion of HepG2 cells in vitro, and inhibited the growth of HepG2-induced tumor in vivo. DJ-1 knockdown altered the malignant behavior of HepG2 cells, potentially through the Akt signaling pathway, suggesting a crucial role for DJ-1 in the oncogenesis of HCC.

Identification of Gem as a new candidate prognostic marker in hepatocellular carcinoma

GTP binding protein overexpressed in skeletal muscle (Gem) is a Ras-related protein whose expression is induced in several cell types upon activation by extracellular stimuli. To investigate the potential roles of Gem in hepatocellular carcinoma (HCC), expression of Gem was examined in human HCC samples. Western blot analysis showed that compared with primary human hepatocytes and adjacent noncancerous tissue, significant down-regulation of Gem was found in HCC cells and tumor tissues. In addition, immunohistochemical analysis of Gem expression was investigated in 108 specimens of HCC tissues. Clinicopathological data were collected to analyze the association with Gem expression. Expression of Gem was significantly negatively correlated with histological grade (P=0.001), tumor size (P=0.020), and vascular invasion (P=0.005), and Gem was also negatively correlated with proliferation marker Ki-67 (P<0.01). More importantly, the Kaplan-Meier survival curves analysis revealed that low expression of Gem was associated with poor prognosis in HCC patients. Univariate analysis showed that Gem expression was associated with poor prognosis (P=0.006). Multivariate analysis indicated that Gem expression was an independent prognostic marker for HCC (P=0.007). Finally, serum starvation and release experiments showed that Gem expression was negatively related with cell proliferation. In the conclusion, our results suggested that down regulation of Gem expression was involved in the pathogenesis of hepatocellular carcinoma, and it might be a favorable independent prognostic parameter for HCC.

Interleukin-37 mediates the antitumor activity in hepatocellular carcinoma: role for CD57+ NK cells

The biological role of interleukin-37 (IL-37) in cancer is large unknown. Through immunohistochemical detection using 163 primary hepatocellular carcinoma (HCC) clinical specimens, we found the expression of IL-37 was decreased in tumor tissues, and the expression level was negatively correlated with tumor size. High expression of IL-37 in HCC tumor tissues was associated with better overall survival (OS) and disease-free survival (DFS). IL-37 expression in tumor tissues was positively associated with the density of tumor-infiltrating CD57+ natural killer (NK) cells, but not with the CD3+ and CD8+ T cells. Consistently, in vitro chemotaxis analysis showed that IL-37- overexpressing HCC cells could recruit more NK cells. The in vivo mouse model experiments also revealed that overexpression IL-37 in HCC cells significantly delayed tumor growth and recruited more NK cells into tumors tissues. Our finding suggested that IL-37 might play an important role for the prognosis of HCC patients via regulating innate immune-action.

Chaperonin containing TCP1, subunit 8 (CCT8) is upregulated in hepatocellular carcinoma and promotes HCC proliferation

The development of molecular pathogenesis of hepatocellular carcinoma (HCC) is complex and involves alterations in the expression and conformation of assorted oncoproteins and tumor suppressors. Chaperonin containing TCP1 (CCT) is a cytolic molecular chaperone complex that is required for the correct folding of numerous proteins. In this study, we investigated a possible involvement of CCT subunit 8 (CCT8) in HCC development. Immunohistochemical analysis was performed in 102 human HCC samples. High CCT8 expression was detected in clinical HCC samples compared with adjacent noncancerous tissues. The univariate and multivariate survival analyses were also performed to determine their prognostic significance. Western blot confirmed the high expression of CCT8 in HCC compared with adjacent normal tissue. Moreover, the biological significance of the aberrant expression of CCT8 was investigated in HCC cell lines. Expression of CCT8 was correlated directly with the histologic grades and tumor size of HCC and high expression of CCT8 was associated with a poor prognosis. CCT8 depletion by siRNA inhibited cell proliferation and blocked S-phase entry in HuH7 cells. These results suggested that CCT8 might be an oncogene and participate in HCC cell proliferation. These findings provide a potential therapeutic strategy for the treatment of HCC.

Tackling hepatitis B virus-associated hepatocellular carcinoma--the future is now

Hepatocellular carcinoma (HCC) is one of the most lethal and prevalent cancers in many developing countries including India. Among the various etiological factors being implicated in the cause of HCC, the most important cause, however, is hepatitis B virus (HBV) infection. Among all HBV genes, HBx is the most critical carcinogenic component, the molecular mechanisms of which have not been completely elucidated. Despite its clinical significance, there exists a very elemental understanding of the molecular, cellular, and environmental mechanisms that drive disease pathogenesis in HCC infected with HBV. Furthermore, there are only limited therapeutic options, the clinical benefits of which are insignificant. Therefore, the quest for novel and effective therapeutic regimen against HBV-related HCC is of paramount importance. This review attempts to epitomize the current state of knowledge of this most common and dreaded liver neoplasm, highlighting the putative treatment avenues and therapeutic research strategies that need to be implemented with immediate effect for tackling HBV-related HCC that has plagued the medical and scientific fraternity for decades. Additionally, this review proposes a novel "five-point" management algorithm for HBV-related HCC apart from portraying the unmet needs, principal challenges, and scientific perspectives that are relevant to controlling this accelerating global health crisis.

Surgical resection versus open-approach radiofrequency ablation for small hepatocellular carcinomas within Milan criteria after successful transcatheter arterial chemoembolization

AIMS

The aim of this study was to compare the effectiveness and safety of hepatic resection versus open-approach RFA (ORFA) for small hepatocellular carcinomas (HCC) within Milan criteria after successful downstaging therapy by transcatheter arterial chemoembolization.

MATERIAL AND METHODS

Between February 2005 and February 2008, a total of 110 patients with advanced HCC met the Milan criteria after successful downstaging therapy; 58 patients then underwent hepatic resection and 52 received ORFA. Outcomes, including short- and long-term morbidity, 1-, 3-, and 5-year mortality and HCC-free survival, were analyzed and compared between the two groups.

RESULTS

Patients in the hepatic resection and ORFA groups showed similar baseline characteristics and downstaging protocols. The ORFA group showed less blood loss, lower hospital costs, shorter surgical time, and fewer hospital stay days (P < 0.05). The 1-, 3-, and 5-year overall survival rates were 94.8, 86.2, and 79.3%, respectively, with liver resection and 96.2, 82.7, and 76.9% with ORFA (P=0.772). The 1-, 3-, and 5-year recurrence-free survival rates were 93.1, 81.0, and 77.6% with resection and 94.2, 76.9, and 73.1% with ORFA (P=0.705). The ORFA patients suffered fewer postoperative complications (P=0.09), particularly among the cases of central HCC (P=0.015).

CONCLUSION

Resection and ORFA achieved similar survival benefits in the management of HCC within Milan criteria after successful downstaging. The decreased blood loss, hospital costs, surgical time, and hospital stay days, and lower complication rates in central cases render ORFA a preferred treatment option.

Evodiamine inhibits 12-O-tetradecanoylphorbol-13-acetate-induced activator protein 1 transactivation and cell transformation in human hepatocytes

Evodia rutaecarpa has been used to treat inflammatory digestive disorders in Asian countries. However, little is known about the antitumor activities of E. rutaecarpa and its bioactive constituent evodiamine (EVO). The aim of this study was to characterize the antitumor mechanisms of E. rutaecarpa and EVO in human hepatocytes. Human Chang liver cells were transfected with activator protein 1 (AP-1)-luciferase reporter gene and designated as Chang/AP-1 cells. The Chang/AP-1 cells were treated with E. rutaecarpa and its bioactive constituents, and challenged with the AP-1 stimulator 12-O-tetradecanoylphorbol-13- acetate (TPA). The present study showed that the methanol extract of E. rutaecarpa decreased the TPA-induced AP-1 transactivation in Chang/AP-1 cells, with an EC₅₀ value of 24.72 μg/mL. EVO inhibited the TPA-induced AP-1 transactivation and colony formation, with EC₅₀ values of 82 μM and 8.2 μM, respectively. Moreover, EVO significantly diminished the TPA-induced phosphorylation of extracellular signal-regulated kinases (ERKs). These results suggested that EVO treatment suppressed the TPA-induced AP-1 activity via the ERKs pathway. In conclusion, EVO inhibited the AP-1 activity and cellular transformation in human hepatocytes, suggesting that EVO was a potential agent for antitumor therapy.

Upregulation of miR-650 is correlated with down-regulation of ING4 and progression of hepatocellular carcinoma

BACKGROUND

In the last decade, studies in hepatocellular carcinoma (HCC) demonstrate dysregulation of miRNAs expression. For instance, miR-650 has been implicated in gastric and colorectal cancer tumorigenicity; however, the role of miR-650 remains unknown in HCC.

METHODS

In this study, we performed a comprehensive analysis to examine the miR-650 expression level in 248 HCC and 120 paracarcinomatous liver (PCL) tissues. The correlations between miR-650 expression level and the clinicopathological characteristics (HCC tumorigenicity) were evaluated. The role of miR-650 played in HCC was investigated by Q-PCR, western blot, and MTT.

RESULTS

We found that miR-650 expression was significantly increased in HCC patients and significantly associated with the patients' age (P = 0.0019), differentiation capability (P = 0.0108), and also tumor stage (P = 0.0069). Moreover, we compared the expression level of both ING4 and miR-650 in 122 HCC patients by western blot and real-time PCR. Statistical result showed a significant negative correlation between them (r(s)  = -0.2011, P = 0.0264). Transfection and MTT test suggested that miR-650 decreased the expression of ING4 and stimulate liver cells proliferation significantly.

CONCLUSION

These data suggested that miR-650 is correlated with the pathogenesis of HCC and is involved in the HCC tumorigenesis process by inhibiting the expression of ING4.

Expression of ADAMTS-1, ADAMTS-4, ADAMTS-5 and TIMP3 by hepatocellular carcinoma cell lines

Little is known about the expression or role of ADAMTS-1, -4 and -5 and their endogenous inhibitor TIMP3 in the liver in physiological and pathological conditions. Their expression was, therefore, investigated in the hepatocellular carcinoma cell lines HepG2 and HuH-7 using qRT-PCR and western blotting, and their cellular localisation by immunocytochemistry. Cytokine treatments were used to assess mRNA and protein modulation. ADAMTS-1, -4, -5 and TIMP3 mRNA and protein were detected in both HepG2 and HuH-7 cells. IL-1β and IL-6 treatments significantly modulated ADAMTS-1 mRNA expression and IL-1β treatment ADAMTS-4 mRNA expression in HepG2 cells. Modulations of mRNA by ≥ 5-fold did not translate to increased protein expression. This study showed that ADAMTS-1, -4, -5 and TIMP3 were expressed at differential levels in hepatocellular carcinoma cell lines. The pro-inflammatory cytokines IL-1β, TNF-α or IL-6 induced changes in mRNA expression, although these did not translate to the protein level.

Identification of LZAP as a new candidate tumor suppressor in hepatocellular carcinoma

Background

LZAP was isolated as a binding protein of the Cdk5 activator p35. LZAP has been highly conserved during evolution and has been shown to function as a tumor suppressor in various cancers. This study aimed to investigate LZAP expression and its prognostic value in hepatocellular carcinoma (HCC). Meanwhile, the function of LZAP in hepatocarcinogenesis was further investigated in cell culture models and mouse models.

Methods

Real-time quantitative PCR, western blot and immunohistochemistry were used to explore LZAP expression in HCC cell lines and primary HCC clinical specimens. The functions of LZAP in the proliferation, colony formation, cell cycle, migration, invasion and apoptosis of HCC cell lines were also analyzed by infecting cells with an adenovirus containing full-length LZAP. The effect of LZAP on tumorigenicity in nude mice was also investigated.

Results

LZAP expression was significantly decreased in the tumor tissues and HCC cell lines. Clinicopathological analysis showed that LZAP expression was significantly correlated with tumor size, histopathological classification and serum α-fetoprotein (AFP). The Kaplan–Meier survival curves revealed that decreasing LZAP expression was associated with poor prognosis in HCC patients. LZAP expression was an independent prognostic marker of overall HCC patient survival in a multivariate analysis. The re-introduction of LZAP expression in the HepG2 and sk-Hep1 HCC cell lines significantly inhibited proliferation and colony formation in the HCC cells and induced G1 phase arrest and apoptosis of the HCC cells in vitro. Restoring LZAP expression in the HCC cell lines also inhibited migration and invasion. In addition, experiments with a mouse model revealed that LZAP overexpression could suppress HCC tumorigenicity in vivo.

Conclusions

Our data suggest that LZAP may play an important role in HCC progression and could be a potential molecular therapy target for HCC.

Overexpression of engulfment and cell motility 1 promotes cell invasion and migration of hepatocellular carcinoma

Engulfment and cell motility 1 (Elmo1) has been linked to the invasive phenotype of glioma cells. The use of Elmo1 inhibitors is currently being evaluated in hepato-cellular carcinoma (HCC), but the molecular mechanisms of their therapeutic effect have yet to be determined. Elmo1 expression in HCC tissue samples from 131 cases and in 5 HCC cell lines was determined by immunohistochemistry, quantitative RT-PCR and Western blotting. To functionally characterize Elmo1 in HCC, Elmo1 expression in the HCCLM3 cell line was blocked by siRNA. Cell migration was measured by wound healing and transwell migration assays in vitro. Elmo1 overexpression was significantly correlated with cell invasion and the poor prognosis of HCC. Elmo1-siRNA-treated HCCLM3 cells demonstrated a reduction in cell migration. The present study demonstrated for the first time that the suppression of Elmo1 expression inhibits cell invasion in HCC.

Involvement of ADAMs in tumorigenesis and progression of hepatocellular carcinoma: Is it merely fortuitous or a real pathogenic link?

Hepatocellular carcinoma (HCC) is the most common primary liver cancer and one of the most frequent types of cancer worldwide. It normally develops in patients with chronic liver disease, especially cirrhosis, although some cases without an apparent underlying liver disease have been reported. The pathogenesis of HCC is multi-factorial and complex. Hepatitis viruses are the main factors favoring the development of HCC. In fact, chronic inflammation associated with hepatitis C or B virus infection can lead to progressive liver fibrosis, cirrhosis and ultimately HCC. Chronic inflammation and liver fibrosis cause a continuous remodeling of the extracellular matrix (ECM), a dynamic process that involves several molecules including integrins and matrix processing enzymes. An increasing body of evidence indicates that ADAMs are involved in promoting tumor formation and progression of HCC. A Disintegrin And Metalloproteases (ADAMs) are a group of proteins belonging to the zinc protease superfamily. ADAMs are usually transmembrane proteins that contain disintegrin and metalloprotease domains and are, therefore, able to carry out both cell adhesion and protease activities. Soluble isoforms of ADAMs have also been discovered and characterized. In this review, we focus on the contribution of ADAM proteins to HCC tumorigenesis and cancer progression. The potential role of ADAMs as key modulators of tumor-stroma interactions during tumor progression, by means of the activities of their constituent domains, is also discussed.

Predicting prognosis in hepatocellular carcinoma after curative surgery with common clinicopathologic parameters

BACKGROUND

Surgical resection is one important curative treatment for hepatocellular carcinoma (HCC), but the prognosis following surgery differs substantially and such large variation is mainly unexplained. A review of the literature yields a number of clinicopathologic parameters associated with HCC prognosis. However, the results are not consistent due to lack of systemic approach to establish a prediction model incorporating all these parameters.

METHODS

We conducted a retrospective analysis on the common clinicopathologic parameters from a cohort of 572 ethnic Chinese HCC patients who received curative surgery. The cases were randomly divided into training (n = 272) and validation (n = 300) sets. Each parameter was individually tested and the significant parameters were entered into a linear classifier for model building, and the prediction accuracy was assessed in the validation set

RESULTS

Our findings based on the training set data reveal 6 common clinicopathologic parameters (tumor size, number of tumor nodules, tumor stage, venous infiltration status, and serum alpha-fetoprotein and total albumin levels) that were significantly associated with the overall HCC survival and disease-free survival (time to recurrence). We next built a linear classifier model by multivariate Cox regression to predict prognostic outcomes of HCC patients after curative surgery This analysis detected a considerable fraction of variance in HCC prognosis and the area under the ROC curve was about 70%. We further evaluated the model using two other protocols; leave-one-out procedure (n = 264) and independent validation (n = 300). Both were found to have excellent prediction power. The predicted score could separate patients into distinct groups with respect to survival (p-value = 1.8e-12) and disease free survival (p-value = 3.2e-7).

CONCLUSION

This described model will provide valuable guidance on prognosis after curative surgery for HCC in clinical practice. The adaptive nature allows easy accommodation for future new biomarker inputs, and it may serve as the foundation for future modeling and prediction for HCC prognosis after surgical treatment.

JNK1, a potential therapeutic target for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the third leading cause of cancer death worldwide. Despite tremendous efforts to diagnose and institute new treatment regimens, the prognosis is still extremely poor. Therefore, knowledge of the molecular mechanisms governing the initiation, maintenance and progression of HCC is urgently needed. Recently, several groups have attributed an important role for c-Jun N-terminal kinase 1 (JNK1) in the pathogenesis of human HCC and its close association with the expression of HCC signature genes. In this review the various associations between JNK1 and HCC are discussed with the hope that targeting this pivotal kinase may lead to novel therapeutic approaches for this fatal disease.

Decreased expression of inhibitor of growth 4 correlated with poor prognosis of hepatocellular carcinoma

OBJECTIVE

Inhibitor of growth 4 (ING4) is a candidate tumor suppressor that plays an important role in tumor growth and angiogenesis. Here, we examined the expression of ING4 in hepatocellular carcinoma (HCC) tissues and analyzed its correlation with the progression of HCC.

METHODS

Specimens from 136 HCC patients were determined immunohistochemically for ING4 expression. The correlation of ING4 levels with clinicopathologic variables, prognosis, and metastatic potential was analyzed. Among the 136 cases, 36 paired HCC and paracarcinomatous liver tissue specimens were analyzed for ING4 expression levels by real-time quantitative reverse transcription-PCR and Western blotting. MVD was determined by CD34 immunostaining to test whether it correlated with ING4 protein expression level.

RESULTS

The ING4 mRNA and protein levels were significantly lower in HCC than paracarcinomatous liver tissue from both real-time quantitative reverse transcription-PCR and Western blotting (P = 0.039 and 0.012, respectively). Importantly, the ING4 protein level correlated with the Edmondson-Steiner grade (P = 0.035), vein invasion (P = 0.015), and microvessel density (P = 0.005). Survival and metastasis analysis indicated that HCC patients with lower ING4 expression had poorer overall survival and disease-free survival than those with high expression (P = 0.0001 and 0.0065; respectively). Multivariable Cox regression analysis revealed that the ING4 expression level was an independent factor for prognosis (hazard risk, 9.63; P = 0.001).

CONCLUSIONS

ING4 expression is down-regulated in HCC tissues. ING4 expression level correlates with prognosis and metastatic potential, which suggests that ING4 is a candidate prognostic marker of HCC.

Differential expression of Caveolin-1 in hepatocellular carcinoma: correlation with differentiation state, motility and invasion

Background

Caveolin-1 is the main component of caveolae membrane structures and has different roles during tumorigenesis in different cancer types with varying expression profiles, indicating that the role of caveolin-1 varies according to tumor type. In this study, we investigated the role and expression of caveolin-1 in hepatocellular carcinogenesis.

Methods

We analyzed the expression of Caveolin-1 in 96 hepatocellular carcinoma (HCC), 29 cirrhosis, 20 normal liver tissues and 9 HCC cell lines by immunostaining and western blotting, respectively. After caveolin-1 was stably transfected to HepG2 and Huh7 cells, the effects of Caveolin-1 on the cellular motility, matrix invasion and anchorage-independent growth were studied. Also, caveolae structure was disrupted in endogenously caveolin expressing cells, SNU 449 and SNU 475 by addition of methyl-β-cyclodextrin and analyzed cellular motility and invasion.

Results

In HCC cell lines, Caveolin-1 expression is correlated to differentiation and basal motility status of these cells. The percentage of Caveolin-1 positivity was found extremely low in normal liver tissue (5%) while it was increased in cirrhosis (45%) and in HCC (66%) (p = 0.002 and p = 0.001 respectively). Cav-1 expression in poorly differentiated HCC samples has been found significantly higher than well differentiated ones (p = 0.001). The caveolin-1 expression was found significantly higher in tumor cells than its peritumoral cirrhotic tissues in HCC samples (p < 0.001). Additionally, the patients with positive staining for Caveolin-1 had significantly higher portal vein invasion than those with negative staining (p = 0.02). Caveolin-1 overexpression increased motility and invasion of HepG2 and Huh7 cells. And disruption of caveolae results in a dramatic decline in both motility and invasion abilities in SNU-449 and SNU-475 cells. Furthermore, caveolin-1 overexpression resulted in down-regulation of E-cadherin while up-regulation of Vimentin. Also, it increased secreted MMP-2 and expression levels of MMP-9 and MT1-MMP. There was no significant difference in colony formation in soft agar between stable clones and parental ones.

Conclusion

In conclusion, stepwise increase in Cav-1 expression in neoplastic stage with respect to pre-neoplastic stage during hepatocellular carcinogenesis and its ability to stimulate HCC cell motility and invasiveness indicate that this protein plays a crucial role in tumor progression.

The disease relevance of human hepatocellular xenograft models: molecular characterization and review of the literature

In recent years a number of new therapeutics has been developed that were not general toxins and inhibitors of cell division like classical chemotherapeutics, but were designed to target a specific pathway. A prerequisite for this development was the comprehensive characterization of molecular alterations occurring in human hepatocellular carcinoma (HCC). However, while much knowledge of the molecular pathogenesis of human HCC has been gained, the model systems used to test the functional relevance of these alterations and applied for preclinical evaluation of drug candidates are still poorly characterized. In this paper, we reviewed the literature about several commonly used HCC cell lines and xenotransplantation models and present our own data on the molecular characterization of these. Results obtained demonstrate that it is important to have a sound knowledge of the specific molecular constitution of the experimental model and to carefully evaluate the functional status of the pathway of interest. For this reason, we make the gene expression profiles publicly available to help researchers making an informed decision about which model to use.

Functional and clinical evidence for NDRG2 as a candidate suppressor of liver cancer metastasis

We searched for potential suppressors of tumor metastasis by identifying the genes that are frequently down-regulated in hepatocellular carcinomas (HCC) while being negatively correlated with clinical parameters relevant to tumor metastasis, and we report here on the identification of N-myc downstream regulated gene 2 (NDRG2) as a promising candidate. NDRG2 expression was significantly reduced in HCC compared with nontumor or normal liver tissues [87.5% (35 of 40) and 62% (62 of 100) at RNA and protein levels, respectively]. Reduction of NDRG2 expression was intimately associated with promoter hypermethylation because its promoter region was found to carry extensively methylated CpG sites in HCC cell lines and primary tumors. Immunohistochemical analysis of NDRG2 protein in 100 HCC patient tissues indicated that NDRG2 expression loss is significantly correlated with aggressive tumor behaviors such as late tumor-node-metastasis (TNM) stage (P = 0.012), differentiation grade (P = 0.024), portal vein thrombi (P = 0.011), infiltrative growth pattern (P = 0.015), nodal/distant metastasis (P = 0.027), and recurrent tumor (P = 0.021), as well as shorter patient survival rates. Ectopically expressed NDRG2 suppressed invasion and migration of a highly invasive cell line, SK-Hep-1, and experimental tumor metastasis in vivo, whereas small interfering RNA-mediated knockdown resulted in increased invasion and migration of a weakly invasive cell line, PLC/PRF/5. In addition, NDRG2 could antagonize transforming growth factor beta1-mediated tumor cell invasion by specifically down-regulating the expression of matrix metalloproteinase 2 and laminin 332 pathway components, with concomitant suppression of Rho GTPase activity. These results suggest that NDRG2 can inhibit extracellular matrix-based, Rho-driven tumor cell invasion and migration and thereby play important roles in suppressing tumor metastasis in HCC.

Blocking transforming growth factor-beta up-regulates E-cadherin and reduces migration and invasion of hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) treatment is challenging because the mechanisms underlying tumor progression are still largely unknown. Transforming growth factor (TGF)-beta1 is considered a crucial molecule in HCC tumorigenesis because increased levels of patients' serum and urine are associated with disease progression. The aim of the present study was to investigate the inhibition of TGF-beta signaling and its impact on HCC progression. Human HCC cell lines were treated with a TGF-beta receptor kinase inhibitor (LY2109761) whose selectivity was determined in a kinase assay. Exogenous TGF-beta1 phosphorylates the TGF-beta receptor, consequently activating Smad-2, whereas the drug selectively blocks this effect and dephosphorylates autocrine p-Smad-2 at concentrations ranging from 0.001 to 0.1 microM. A cytotoxic effect documented by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT), trypan blue, and propidium iodide staining assays was observed at 10microM, whereas the drug inhibits (P < 0.001) the migration of HCC cells on fibronectin, laminin-5, and vitronectin and invasion through Matrigel (P < 0.001) at concentrations up to 0.1 microM. LY2109761 up-regulates (P < 0.001) E-cadherin mRNA and protein levels. This increase was localized at the cellular membrane where E-cadherin mediates anchorage that is cell-cell dependent. Consistently, a functional monoclonal antibody that inhibits E-cadherin-dependent cell-cell contact restores the migratory and invasive activity. Finally, nonmetastatic HCC tissues from 7 patients were cultured with TGF-beta1 in the presence or absence of LY2109761. E-cadherin expression was reduced by TGF-beta1 and was significantly (P < 0.0001) increased by LY2109761 treatment, measured by quantitative real-time PCR on microdissected tissues and by immunohistochemistry on serial sections. In 72 patients, E-cadherin tissue expression was more weakly expressed in metastatic than in nonmetastatic HCC (P < 0.0001).

CONCLUSION

LY2109761 blocks migration and invasion of HCC cells by up-regulating E-cadherin, suggesting that there could be a mechanistic use for this molecule in clinical trials.

Targeting stromal cells for the treatment of platelet-derived growth factor C-induced hepatocellular carcinogenesis

Non-invasive therapies for the treatment of hepatocellular carcinoma (HCC) would be of great benefit to public health. To this end, we have developed a platelet-derived growth factor-C (PDGF-C) transgenic (Tg) mouse model, which mimics many aspects of human liver carcinogenesis. Specifically, overexpression of PDGF-C results in liver fibrosis, which is preceded by activation and proliferation of hepatic stellate cells, and is followed by the development of dysplastic lesions and angiogenesis, and progression to HCCs by 8 months of age. Here, we show that PDGF-C overexpression induces the proliferation of endothelial-like cells that are present in tumors and adjacent non-neoplastic parenchyma. The protein tyrosine kinase inhibitor, imatinib (Gleevec), decreases the proliferation of non-parenchymal cells (NPC) in vitro and in vivo, with concomitant inhibition of Akt. In vivo treatment with imatinib also blocks the expression of CD34 in PDGF-C Tg mice. Decreased NPC proliferation and CD34 expression correlated with lower levels of active ERK1/2 and total levels of PDGF receptor alpha (PDGFRalpha). In summary, the small molecule inhibitor imatinib attenuates stromal cell proliferation in PDGF-C-induced HCC, which coincides with decreased expression of both CD34 and PDGFRalpha, and activated Akt. Our findings suggest that imatinib may be efficacious in the treatment of hepatocarcinogenesis, particularly when neovascularization is present.

EGFR and VEGFR as potential target for biological therapies in HCC cells

Hepatocellular carcinoma (HCC) is a highly malignant cancer with poor prognosis. Inhibitors of EGFR and VEGFR for HCC treatment are currently under investigation. Gefitinib and vandetanib inhibit migration of HCC cells on Laminin-5 and Fibronectin, and invasion through matrigel. Both drugs inhibit p-EGFR after short time, while their efficacy on p-Erk1/2 and p-Akt is progressive and stable over time. PI3K/Akt and MEK/Erk1/2 inhibitors, inhibit migration and invasion as well as inducing de-phosphorylation of downstream effectors. Finally, both inhibitors, vandetanib and gefitinib down-regulated the secretion of matrix metalloproteases MMP-2 and MMP-9. All these biological effects seem to depend on the activity of gefitinib and vandetanib blocking activity towards p-EGFR mediated pathways.

Laminin-5 stimulates hepatocellular carcinoma growth through a different function of alpha6beta4 and alpha3beta1 integrins

Hepatocellular carcinoma (HCC) growth severely affects prognosis. Ki-67, a known marker of cell proliferation, is a negative prognostic factor in HCC. Growth factors such as the epidermal growth factor (EGF) induce HCC cell proliferation but do not explain the great heterogeneity of HCC growth. Laminin-5 (Ln-5) is an extracellular matrix protein (ECM) present in the tissue microenvironment of HCC. The two main receptors for Ln-5, integrins alpha3beta1 and alpha6beta4, are expressed on the cell surface of HCC cells. The aim of this study is to investigate an alternative mechanism of HCC growth whereby Ln-5 promotes HCC cell proliferation through alpha3beta1 and alpha6beta4. HCC tissues containing Ln-5 display a larger diameter and higher number of positive cells for Ki-67, a well known proliferative index, as determined by double immunofluorescence staining and real-time PCR on microdissected tissues. In vitro, Ln-5, but not collagen I, collagen IV or fibronectin, induces proliferation as much as EGF does, via Erk phosphorylation as a consequence of beta4 integrin phosphorylation. However, the two HCC cell lines do not proliferate in presence of Ln-5 despite beta4 integrin and Erk1/2 activation. After transfection with alpha3 integrin, in the presence of Ln-5 one of these HCC cell lines acquires a proliferative activity whereas one of the proliferative HCC cell lines, knocked-down for alpha3 integrin, loses its proliferative activity.

CONCLUSIONS

Our study suggests a new mechanism of HCC growth whereby Ln-5 stimulates proliferation via a different function of alpha6beta4 and alpha3beta1.