Hepatocellular carcinoma in 2011 and beyond: from the pathogenesis to molecular targeted therapy

Hepatocarcinoma Induces a Tumor Necrosis Factor-Dependent Kupffer Cell Death Pathway That Favors Its Proliferation Upon Partial Hepatectomy

Partial hepatectomy (PH) is the main treatment for early-stage hepatocellular carcinoma (HCC). Yet, a significant number of patients undergo recursion of the disease that could be linked to the fate of innate immune cells during the liver regeneration process. In this study, using a murine model, we investigated the impact of PH on HCC development by bioluminescence imaging and flow cytometry. While non-resected mice were able to control and reject orthotopic implanted Hepa1-6 hepatocarcinoma cells, resected liver underwent an increased tumoral proliferation. This phenomenon was associated with a PH-induced reduction in the number of liver-resident macrophages, i.e., Kupffer cells (KC). Using a conditional ablation model, KC were proved to participate in Hepa1-6 rejection. We demonstrated that in the absence of Hepa1-6, PH-induced KC number reduction was dependent on tumor necrosis factor-alpha (TNF-α), receptor-interacting protein kinase (RIPK) 3, and caspase-8 activation, whereas interleukin (IL)-6 acted as a KC pro-survival signal. In mice with previous Hepa1-6 encounter, the KC reduction switched toward a TNF-α-RIPK3–caspase-1 activation. Moreover, KC disappearance associated with caspase-1 activity induced the recruitment of monocyte-derived cells that are beneficial for tumor growth, while caspase-8-dependent reduction did not. In conclusion, our study highlights the importance of the TNF-α-dependent death pathway induced in liver macrophages following partial hepatectomy in regulating the antitumoral immune responses.

Mir-765 promotes cell proliferation by downregulating INPP4B expression in human hepatocellular carcinoma

microRNAs (miRNAs) dysregulation is widely involved in cancer progression and contributed to sustained cell proliferation by directly targeting multiple targets. Therefore, better understanding the underlying mechanism of miRNA in carcinogenesis may improve diagnostic and therapeutic strategies for malignancy. In our study, we found that mir-765 is upregulated in both hepatocellular carcinoma (HCC) cell lines and tissues, compared to human normal liver cell line and adjacent non-cancerous tissues, respectively. Overexpression of mir-765 increased HCC cells proliferation and tumorigenicity, whereas inhibition of mir-765 reverses this effect. Furthermore, we demonstrated that INPP4B as a direct target of mir-765 and ectopic expression of mir-765 repressed INPP4B expression, resulting in upregulation of p-AKT, Cyclin D1, and downregulation of p-FOXO3a, p21 expression in HCC. Strikingly, we found that silencing the expression of INPP4B is the essential biological function of miR-765 during HCC cell proliferation. Collectively, our findings reveal that miR-765 is a potential onco-miR that participates in carcinogenesis of human HCC by suppressing INPP4B expression, and might represent a potential therapeutic target for HCC patients.

TRIM11 Upregulation Contributes to Proliferation, Invasion, and EMT of Hepatocellular Carcinoma Cells

The tripartite motif-containing protein 11 (TRIM11), a member of the TRIM protein family, has attracted much attention because of its involvement in the development of the central nervous system. It has gained renewed focus because of its newly found function in promoting tumors. However, little is known about its role in hepatocellular carcinoma (HCC). In the present study, we found TRIM11 to be overexpressed in HCC tissues and cell lines. Downregulation of TRIM11 inhibited HCC cell proliferation and invasion in vitro and in vivo as well as suppressed the epithelial–mesenchymal transition (EMT) process. In addition, downregulation of TRIM11 decreased the protein expression levels of p-PI3K and p-Akt in HCC cells and thus inhibited activation of the PI3K/Akt signaling pathway. Based on these results, we suggest the importance of TRIM11 in HCC progression and the potential of TRIM11 as a therapeutic target for HCC.

Biomarkers for Hepatocellular Carcinoma (HCC): An Update

The past decades have witnessed increased use of biomarkers in disease management. A biomarker is any characteristic that can be objectively measured and evaluated as an indicator of normal biological process, pathogenic process, or pharmacological response to a therapeutic intervention. The clinical measurements of biomarkers can be carried out in vivo using imaging modalities like ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI), as well as in vitro utilizing serum or plasma or other body fluids as specimens. In contrast to the imaging modalities, a prominent value of serum biomarkers is that they could be biologically relevant and disease-specific to pathophysiologic or pathologic process of disease development. This article provides an update of serum biomarkers for hepatocellular carcinoma (HCC) in risk assessment for early detection through surveillance.

Nanoelectroablation of Murine Tumors Triggers a CD8-Dependent Inhibition of Secondary Tumor Growth

We have used both a rat orthotopic hepatocellular carcinoma model and a mouse allograft tumor model to study liver tumor ablation with nanosecond pulsed electric fields (nsPEF). We confirm that nsPEF treatment triggers apoptosis in rat liver tumor cells as indicated by the appearance of cleaved caspase 3 and 9 within two hours after treatment. Furthermore we provide evidence that nsPEF treatment leads to the translocation of calreticulin (CRT) to the cell surface which is considered a damage-associated molecular pattern indicative of immunogenic cell death. We provide direct evidence that nanoelectroablation triggers a CD8-dependent inhibition of secondary tumor growth by comparing the growth rate of secondary orthotopic liver tumors in nsPEF-treated rats with that in nsPEF-treated rats depleted of CD8+ cytotoxic T-cells. The growth of these secondary tumors was severely inhibited as compared to tumor growth in CD8-depleated rats, with their average size only 3% of the primary tumor size after the same one-week growth period. In contrast, when we depleted CD8+ T-cells the second tumor grew more robustly, reaching 54% of the size of the first tumor. In addition, we demonstrate with immunohistochemistry that CD8+ T-cells are highly enriched in the secondary tumors exhibiting slow growth. We also showed that vaccinating mice with nsPEF-treated isogenic tumor cells stimulates an immune response that inhibits the growth of secondary tumors in a CD8+-dependent manner. We conclude that nanoelectroablation triggers the production of CD8+ cytotoxic T-cells resulting in the inhibition of secondary tumor growth.

Mediator subunit 23 overexpression as a novel target for suppressing proliferation and tumorigenesis in hepatocellular carcinoma

BACKGROUND AND AIM

Hepatocellular carcinoma (HCC) is the fifth most frequent cancer in the world. However, the molecular mechanisms involved in HCC are still poorly understood. Here, we study the role of mediator subunit 23 (MED23), a component of the Mediator complex, in hepatocarcinogenesis.

METHODS

We detected MED23 expression in HCC samples by real-time polymerase chain reaction (PCR) and immunohistochemistry analysis. We also knocked down and overexpressed MED23 to explore its functional role in hepatoma cell growth. The cell cycle was examined by flow cytometry analysis, and protein expression was examined by Western blot. A xenograft mouse model was used to determine whether MED23 is involved in tumorigenesis.

RESULTS

MED23 was frequently upregulated in human HCC tissues compared with paired adjacent non-tumorous liver tissues. The hepatoma cells also showed increased MED23 expression. MED23 knockdown inhibited hepatoma cell growth, whereas overexpression of MED23 promoted cell growth. Knockdown of MED23 induced a G1 to S phase arrest. Moreover, MED23 regulated the expression of p16(INK) (4a) (p16) and the phosphorylation of retinoblastoma protein (Rb). p16 was transcriptionally upregulated, and its promoter was demethylated. The G1 to S phase arrest induced by MED23 knockdown was aborted after p16 was silenced. Furthermore, MED23 knockdown suppressed tumorigenesis and regulated p16/Rb signaling in vivo.

CONCLUSIONS

Taken together, our study suggests that MED23 plays an important role in hepatocarcinogenesis, and it may be a novel target for HCC therapy.

MicroRNA-133a inhibits cell proliferation, colony formation ability, migration and invasion by targeting matrix metallopeptidase 9 in hepatocellular carcinoma

MicroRNA‑133a (miR‑133a) is downregulated in various types of human malignancy, including hepatocellular carcinoma (HCC), renal cell carcinoma, esophageal squamous cell carcinoma, bladder cancer, ileal carcinoid and rhabdomyosarcoma. The aim of the present study was to examine the effects of miR‑133a on HCC cell proliferation, colony formation, migration and invasion. miR‑133a was transfected into the HCC HepG2 and SMMC‑7721 cell lines and the expression levels of miR‑133a were determined; in addition, cell viability assays, colony formation assays, cell migration assays, cell invasion assays, western blot analyses and luciferase assays were performed in the HCC cell lines. The results demonstrated that miR‑133a significantly inhibited cell proliferation, colony formation, migration and invasion in HepG2 and SMMC‑7721 cells. To the best of our knowledge, the present study also provided the first evidence that miR‑133a directly downregulated the expression of matrix metallopeptidase 9 (MMP‑9) in the HCC cells. In conclusion, the results of the present study indicated that miR‑133a may have suppressed cell proliferation, colony formation, migration and invasion via the downregulation of MMP‑9 in HCC cell lines. Therefore, MMP‑9 may be used for the development of novel molecular markers and therapeutic approaches to inhibit hepatocellular carcinoma metastasis.

Effect of liver regeneration on malignant hepatic tumors

Liver regeneration after major surgery may activate occult micrometastases and facilitate tumor growth, leading to liver tumor recurrence. Molecular changes during liver regeneration can provide a microenvironment that stimulates intrahepatic tumor propagation through alterations in cellular signaling pathways, where activation and proliferation of mature hepatocytes, hepatic progenitor cells, non-parenchymal liver cells might favor both liver regeneration and tumor growth. This review highlights recent advances of tumor growth and development in the regenerating liver, possible mechanisms and clinical implications.

Synergistic effect of MiR-146a mimic and cetuximab on hepatocellular carcinoma cells

Previously, we found that the expression of microRNA-146a (miR-146a) was downregulated in hepatocellular carcinoma (HCC) formalin-fixed paraffin-embedded (FFPE) tissues compared to the adjacent noncancerous hepatic tissues. In the current study, we have explored the in vitro effect of miR-146a on the malignant phenotypes of HCC cells. MiR-146a mimic could suppress cell growth and increase cellular apoptosis in HCC cell lines HepG2, HepB3, and SNU449, as assessed by spectrophotometry, fluorimetry, and fluorescence microscopy, respectively. Furthermore, western blot showed that miR-146a mimic downregulated EGFR, ERK1/2, and stat5 signalings. These effects were less potent compared to that of a siRNA targeting EGFR, a known target gene of miR-146a. Moreover, miR-146a mimic could enhance the cell growth inhibition and apoptosis induction impact of various EGFR targeting agents. The most potent combination was miR-146a mimic with cetuximab, presenting a synergistic effect. In conclusion, miR-146a plays a vital role in the cell growth and apoptosis of HCC cells and inducing miR-146a level might be a critical targeted molecular therapy strategy for HCC.

Expression and clinicopathological significance of miR-146a in hepatocellular carcinoma tissues

BACKGROUND

Aberrant expression of microRNA-146a (miR-146a) has been found in several classes of cancers. However, its expression and clinicopathological contribution in hepatocellular carcinoma (HCC) has not been fully elucidated.

OBJECTIVE

To explore the clinicopathological significance of the miR-146a level in HCC formalin-fixed paraffin-embedded (FFPE) tissue.

METHODS

Eighty-five HCC samples and their para-cancerous normal liver tissues were collected. Total mRNA including miRNA was extracted, and miR-146a expression was determined using real-time RT-PCR. Furthermore, the correlation between the miR-146a expression and clinicopathological parameters was investigated.

RESULTS

MicroRNA-146a expression in HCC tissues was lower compared with that in adjacent non-cancerous hepatic tissues. MicroRNA-146a expression was also related to clinical TNM stage, metastasis, portal vein tumor embolus, and number of tumor nodes.

CONCLUSIONS

Down-regulation of miR-146a is related to HCC carcinogenesis and deterioration of HCC. MicroRNA-146a may act as a suppressor miRNA of HCC, and it is therefore a potential prognostic biomarker for HCC patients.

Pro-angiogenic cytokines for prediction of outcomes in patients with advanced hepatocellular carcinoma

Background:

We previously reported that expressions of the pro-angiogenic cytokines angiopoietin-2 (Ang-2), follistatin, granulocyte colony-stimulating factor, hepatocyte growth factor, leptin, platelet-derived growth factor-BB, platelet endothelial cell adhesion molecule-1, and vascular endothelial growth factor were associated with the response to sorafenib in patients with advanced hepatocellular carcinoma (HCC). The aim of the present study is to examine the same relationship in a larger cohort.

Methods:

In the current retrospective cohort study, we measured serum levels of the eightcytokines in 120 consecutive HCC patients who were treated with sorafenib. We evaluated the effects of increased expression of serum cytokines on progression-free survival (PFS) and overall survival (OS).

Results:

Elevated expression of Ang-2 correlated both with significantly shorter PFS (hazard ratio (HR), 1.84; 95% confidence interval (CI), 1.21–2.81), and OS (HR, 1.95; 95% CI, 1.21–3.17). Patients with more than three cytokines expressed above the median similarly had significantly shorter PFS (HR, 1.98; 95% CI, 1.30–3.06) and OS (HR, 1.94; 95% CI, 1.19–3.22). Differences in OS were evident in cases with the evidence of macroscopic vascular invasion or extrahepatic metastasis.

Conclusion:

High expression of Ang-2 or more than cytokines in serum is associated with poor PFS and OS in HCC patients treated with sorafenib.

A comparison of surgical outcomes for noncirrhotic and cirrhotic hepatocellular carcinoma patients in a Western institution

BACKGROUND

Although cirrhosis is common among Western hepatocellular carcinoma (HCC) patients, a substantial proportion are not cirrhotic. Studies examining surgical outcomes in noncirrhotic patients primarily evaluate Asian populations and liver resections. We describe cirrhotic and noncirrhotic HCC patients undergoing resection and transplantation at a Western institution.

METHODS

We retrospectively reviewed 188 HCC patients treated surgically from 2000 to 2011 at a single Western institution. The primary endpoint was recurrence. Secondary endpoints included time to recurrence and overall survival.

RESULTS

We evaluated 138 cirrhotic and 50 noncirrhotic patients with a median follow-up of 33.8 months. Noncirrhotics mostly underwent liver resection (90%), whereas cirrhotics primarily underwent transplantation (67%). Hepatitis B was the most common underlying liver disease for noncirrhotics (64%), whereas hepatitis C (55%) and alcohol abuse (32%) predominated among cirrhotics. Pathologic evaluation demonstrated tumors in noncirrhotics that were fewer in number, larger, less differentiated, and more likely to have vascular invasion. Recurrence was more common for noncirrhotics (36 vs. 18%; P = .008) and more common after resection compared with transplantation. Overall median survival was 46.9 months for both groups. After resection, noncirrhotics had longer survival times than did cirrhotics (41.6 vs. 32.9 months; P = .04). Vascular invasion was an independent predictor for recurrence; tumor size was a predictor of mortality.

CONCLUSION

Noncirrhotics in our Western cohort had higher risk pathologic features, more frequently underwent resection, and suffered more recurrences than did cirrhotics. Overall survival was similar for both groups. Prospective studies of noncirrhotic HCC patients in Asia and Western countries may inform surveillance and treatment.

Increased miR-221 expression in hepatocellular carcinoma tissues and its role in enhancing cell growth and inhibiting apoptosis in vitro

Background

MiR-221 is over-expressed in human hepatocellular carcinoma (HCC), but its clinical significance and function in HCC remains uncertain. The aim of the study was to investigate the relationship between miR-221 overexpression and clinicopathological parameters in HCC formalin-fixed paraffin-embedded (FFPE) tissues, and the effect of miR-221 inhibitor and mimic on different HCC cell lines in vitro.

Methods

MiR-221 expression was detected using real time RT-qPCR in FFPE HCC and the adjacent noncancerous liver tissues. The relationship between miR-221 level and clinicopathological features was also analyzed. Furthermore, miR-221 inhibitor and mimic were transfected into HCC cell lines HepB3, HepG2 and SNU449. The effects of miR-221 on cell growth, cell cycle, caspase activity and apoptosis were also investigated by spectrophotometry, fluorimetry, fluorescence microscopy and flow cytometry, respectively.

Results

The relative expression of miR-221 in clinical TNM stages III and IV was significantly higher than that in the stages I and II. The miR-221 level was also upregulated in the metastatic group compared to the nonmetastatic group. Furthermore, miR-221 over-expression was related to the status of tumor capsular infiltration in HCC clinical samples. Functionally, cell growth was inhibited, cell cycle was arrested in G1/S-phase and apoptosis was increased by miR-221 inhibitor in vitro. Likewise, miR-221 mimic accelerated the cell growth.

Conclusions

Expression of miR-221 in FFPE tissues could provide predictive significance for prognosis of HCC patients. Moreover, miR-221 inhibitor could be useful to suppress proliferation and induce apoptosis in HCC cells. Thus miR-221 might be a critical targeted therapy strategy for HCC.

Perspectives on the design of clinical trials combining transarterial chemoembolization and molecular targeted therapy

Transarterial chemoembolization (TACE) moderately prolongs the survival of patients with intermediate-stage hepatocellular carcinoma. Molecular targeted therapy (MTT) may improve the efficacy of TACE. However, the findings of clinical trials evaluating the efficacy of a combination of TACE and MTT are conflicting. We hypothesized that this disparity can be prevented using alternative study designs. In this review, we classify the pertinent issues of study designs into five domains: primary endpoints, patients, TACE procedures, timing of randomization, and drug administration. Furthermore, we discuss the methods for increasing the success rate by minimizing potentially confounding factors within these five domains. Transarterial chemoembolization (TACE) is the current standard therapy for patients with Barcelona Clinic Liver Cancer (BCLC) intermediate-stage hepatocellular carcinoma (HCC) [1, 2, 3]. The survival benefit of TACE is supported by the results of meta-analysis of clinical trials comparing TACE with other conservative treatments in patients with inoperable HCC [4]. The results showed that the median survival of patients improved from approximately 16 to 20 months following TACE [4, 5]. Although advances in TACE techniques and the use of new embolization agents may improve the efficacy of TACE [6, 7], other approaches are needed to further improve the outcome in HCC patients treated using TACE. Molecular targeted therapy (MTT) has improved the survival of patients with advanced-stage HCC [5, 8]. Therefore, combining MTT and TACE may additionally improve the survival in patients with intermediate-stage HCC. Many molecular targeted agents (MTA) are currently undergoing evaluation in randomized trials (table 1). However, the designs of these trials differ significantly. The results of two trials combining sorafenib and TACE were recently reported. Both trials failed to demonstrate a therapeutic benefit of the combination therapy for time to tumor progression (TTP) or overall survival (OS) [9, 10]. However, specific subgroups of patients who received treatment for more than 6 months exhibited significantly better survival (table 2). Because median survival can be greater than 2 years in patients with intermediate-stage HCC, it is likely that an extended exposure period is necessary for MTA effects to reach the biological threshold at which survival benefit becomes measurable. Therefore, early discontinuation of study drug treatment may significantly undermine the statistical power of efficacy analysis in randomized trials (fig. 1). Clinical trials should be designed to minimize confounding factors that could lead to early discontinuation of study drug [1, 2, 3, 11, 12]. Factors that are crucial in this regard can be categorized into five domains: (1) selection of primary endpoints, (2) selection of patient population, (3) selection of TACE procedures, (4) timing of randomization, and (5) study drug administration. In this review we discuss the confounding effects potentially associated with each domain and the possible interactions among domains in trials combining TACE and MTA. We also discuss strategies that can help improve sensitivity and accuracy measurements of MTA efficacy.