Emerging approaches in hepatocellular carcinoma

Detecting GPC3-Expressing Hepatocellular Carcinoma with L5 Peptide-Guided Pretargeting Approach: In Vitro and In Vivo MR Imaging Experiments

Objective

To investigate the potential of L5 peptide-guided pretargeting approach to identify GPC3-expressing hepatocellular carcinoma (HCC) using ultrasmall superparamagnetic iron oxide (USPIO) as the MR probe.

Methods

Immunofluorescence with carboxyfluorescein- (FAM-) labeled L5 peptide was performed in HepG2 cells. Polyethylene glycol-modified USPIO (PEG-USPIO) and its conjugation with streptavidin (SA-PEG-USPIO) were synthesized, and their hydrodynamic diameters, zeta potential, T₂ relaxivity, and cytotoxicity were measured. In vitro and in vivo two-step pretargeting MR imaging was performed on HepG2 cells and tumor-bearing mice after the administration of biotinylated L5 peptide (first step), followed by SA-PEG-USPIO (second step). Prussian blue staining was performed to assess iron deposition in tumors.

Results

The high specificity of L5 peptide for GPC3 was demonstrated. Generation of SA-PEG-USPIO nanoparticles with good biocompatibility (an average hydrodynamic diameter of 35.97 nm and a zeta potential of -7.91 mV), superparamagnetism (R ₂ = 0.1039 × 10³ mM^-1s^-1), and low toxicity was achieved. The pretargeting group showed more enhancement than the nonpretargeting group both in vitro (60% vs 20%, P < 0.05) and in vivo (32% vs 6%, P < 0.001). Substantial iron deposition was only observed in HepG2 cells and tumors in the pretargeting group.

Conclusion

L5 peptide-guided, two-step pretargeting approach with USPIO as the MR imaging probe is a lucrative strategy to specifically identify GPC3-expressing HCC.

Cancer stem cells in hepatocellular carcinoma--an immunohistochemical study with histopathological association

Background & objectives:

Cancer stem cells (CSCs) may be responsible for tumour recurrence and resistance to chemotherapy in hepatocellular carcinoma (HCC). This study was carried out to evaluate the association between histological parameters and liver CSCs (LCSC) in HCC, and to compare distribution of liver CSCs in HCC associated with and without hepatitis B virus (HBV) infection.

Methods:

Seventy nine tumours (49 surgical resections from 46 patients, and 30 from autopsy) were reviewed. Immunohistochemical staining for the LCSC marker EpCAM (epithelial cell adhesion molecule), liver progenitor cell (LPC) markers CK19 (cytokeratin 19) and neural cell adhesion molecule (NCAM) were performed and were associated with histological features of tumour behaviour.

Results:

Thirty three tumours (41.8%) showed positive staining for EpCAM. CK19 and NCAM expression were seen in 26 (32.9%) and four (5.1%) tumours, respectively. The expression of EpCAM and CK19 was significantly associated with each other (P<0.001). EpCAM expression was significantly associated with clinical and histological features indicating aggressive tumour behaviour, including younger age of onset, higher serum alpha foetoprotein (AFP) levels, tumour cell dedifferentiation, increased mitotic activity, and vascular invasiveness. There was no significant difference in expression of EpCAM, CK19 and NCAM between HBV positive and negative HCC.

Interpretation & conclusions:

The LCSC marker EpCAM was expressed in less than half of HCC, was independent of HBV aetiology, and was strongly associated with clinical and histological features of aggressive tumour behaviour. Positive staining for CK19 suggests a possible LPC origin of the EpCAM positive HCCs.

Image-guided radiation therapy for liver tumors: gastrointestinal histology matters

OBJECTIVES

To describe the safety and efficacy of single-fraction and hypofractionated image-guided radiotherapy techniques for the treatment of large liver tumors.

METHODS

Forty-six patients, with 50 tumors (10 primary liver tumors, 40 liver metastases) from March 2004 to March 2011 were reviewed. The maximal tumor diameter ranged from 1.2 to 11.3 cm (median, 4.2 cm). Eighty-seven percent of patients received prior systemic chemotherapy. Fifty-nine percent had prior invasive local therapy including surgery, ablation, or embolization. Twenty-five lesions were treated with hypofractionated therapy (24 to 30 Gy in 3 to 5 fractions), whereas 19 received a single fraction (18 or 24 Gy). Local control (LC) was calculated using competing risk analysis. Overall survival was calculated by the Kaplan-Meier method.

RESULTS

Median follow-up for all patients was 29.8 months (range, 3 to 46 mo). The median survival was 15.4 months. The 1- and 2-year LC rates were 78% and 75%, respectively. Dose and tumor size had no significant effect on tumor progression. The local progression at 1 and 2 years was 29% and 32% for gastrointestinal (GI) histologies versus 0% for non-GI histologies (P=0.02). Tumor volumes larger than 112 cm correlated with decreased survival (P=0.05). Three patients developed late grade 3 GI stricture or ulceration.

CONCLUSIONS

Image-guided radiotherapy for liver tumors achieves good rates of LC with minimal toxicity at 1 and 2 years even in patients with large or recurrent disease that has been heavily pretreated. GI histology demonstrated decreased LC rates. Further management strategies should be considered in these patients.

Dual mode single agent thermochemical ablation by simultaneous release of heat energy and acid: hydrolysis of electrophiles

PURPOSE

This study aimed to investigate two readily available electrophilic reagents, acetyl chloride (AcCl), and acetic anhydride (Ac(2)O), for their potential in tissue ablation.

MATERIALS AND METHODS

Reagents were diluted in diglyme as solutions up to 8 mol/L and tested in a gel phantom with NaOH solutions and ex vivo in porcine liver. Temperature, pH, and volume measurements were obtained. Infrared and gross pathological images were obtained in bisected specimens immediately after injection.

RESULTS

AcCl was much more reactive than Ac(2)O and AcCl was therefore used in the tissue studies. Temperature increases of up to 37°C were noted in vitro and 30°C in ex vivo tissues using 4 mol/L AcCl solutions. Experiments at 8 mol/L were abandoned due to the extreme reactivity at this higher concentration. A change in pH of up to 4 log units was noted with 4 mol/L solutions of AcCl with slight recovery over time. Ablated volumes were consistently higher than injected volumes.

CONCLUSIONS

Reaction of electrophiles in tissues shows promise as a new thermochemical ablation technique by means of only a single reagent. Further studies in this area are warranted.

Hepatitis B virus X protein upregulates mTOR signaling through IKKβ to increase cell proliferation and VEGF production in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), a major cause of cancer-related death in Southeast Asia, is frequently associated with hepatitis B virus (HBV) infection. HBV X protein (HBx), encoded by a viral non-structural gene, is a multifunctional regulator in HBV-associated tumor development. We investigated novel signaling pathways underlying HBx-induced liver tumorigenesis and found that the signaling pathway involving IκB kinase β (IKKβ), tuberous sclerosis complex 1 (TSC1), and mammalian target of rapamycin (mTOR) downstream effector S6 kinase (S6K1), was upregulated when HBx was overexpressed in hepatoma cells. HBx-induced S6K1 activation was reversed by IKKβ inhibitor Bay 11-7082 or silencing IKKβ expression using siRNA. HBx upregulated cell proliferation and vascular endothelial growth factor (VEGF) production, and these HBx-upregulated phenotypes were abolished by treatment with IKKβ inhibitor Bay 11-7082 or mTOR inhibitor rapamycin. The association of HBx-modulated IKKβ/mTOR/S6K1 signaling with liver tumorigenesis was verified in a HBx transgenic mouse model in which pIKKβ, pS6K1, and VEGF expression was found to be higher in cancerous than non-cancerous liver tissues. Furthermore, we also found that pIKKβ levels were strongly correlated with pTSC1 and pS6K1 levels in HBV-associated hepatoma tissue specimens taken from 95 patients, and that higher pIKKβ, pTSC1, and pS6K1 levels were correlated with a poor prognosis in these patients. Taken together, our findings demonstrate that HBx deregulates TSC1/mTOR signaling through IKKβ, which is crucially linked to HBV-associated HCC development.

Hepatitis B virus X protein upregulates mTOR signaling through IKKβ to increase cell proliferation and VEGF production in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), a major cause of cancer-related death in Southeast Asia, is frequently associated with hepatitis B virus (HBV) infection. HBV X protein (HBx), encoded by a viral non-structural gene, is a multifunctional regulator in HBV-associated tumor development. We investigated novel signaling pathways underlying HBx-induced liver tumorigenesis and found that the signaling pathway involving IκB kinase β (IKKβ), tuberous sclerosis complex 1 (TSC1), and mammalian target of rapamycin (mTOR) downstream effector S6 kinase (S6K1), was upregulated when HBx was overexpressed in hepatoma cells. HBx-induced S6K1 activation was reversed by IKKβ inhibitor Bay 11-7082 or silencing IKKβ expression using siRNA. HBx upregulated cell proliferation and vascular endothelial growth factor (VEGF) production, and these HBx-upregulated phenotypes were abolished by treatment with IKKβ inhibitor Bay 11-7082 or mTOR inhibitor rapamycin. The association of HBx-modulated IKKβ/mTOR/S6K1 signaling with liver tumorigenesis was verified in a HBx transgenic mouse model in which pIKKβ, pS6K1, and VEGF expression was found to be higher in cancerous than non-cancerous liver tissues. Furthermore, we also found that pIKKβ levels were strongly correlated with pTSC1 and pS6K1 levels in HBV-associated hepatoma tissue specimens taken from 95 patients, and that higher pIKKβ, pTSC1, and pS6K1 levels were correlated with a poor prognosis in these patients. Taken together, our findings demonstrate that HBx deregulates TSC1/mTOR signaling through IKKβ, which is crucially linked to HBV-associated HCC development.

Targeting of hepatocellular carcinoma with glypican-3-targeting peptide ligand

Hepatocellular carcinoma is a common malignancy. The carcinoma cells express glypican-3 (GPC-3) on the cell membrane. GPC-3 is also expressed in melanoma cells. Therefore, GPC-3 might be a potential target for tumor imaging or therapy. Here, proteomic mass spectrometry was used to identify peptides that target GPC-3-expressing tumors. A mammalian expression vector expressing a FLAG-GPC-3 fusion protein was cloned for immunoprecipitation. With the use of liposomes, the vector was transfected into HepG2 (HepG2/FLAG-GPC-3) and HEK 293 cells, and the transfected cell lines were selected with geneticin. HepG2/FLAG-GPC-3 cells were used for immunoprecipitation of FLAG-GPC-3 fusion protein. Seven peptide candidates (L1-L7) were selected for GPC-3-targeting ligands by mass spectrometric analysis. The L5 peptide with 14 amino acids (Arg-Leu-Asn-Val-Gly-Gly-Thr-Tyr-Phe-Leu-Thr-Thr-Arg-Gln) showed selective binding to the GPC-3-expressing tumor cells, as did a shortened L5 peptide (L5-2) with seven amino acids (Tyr-Phe-Leu-Thr-Thr-Arg-Gln). These peptide ligands have potential as targeting moieties to GPC-3-expressing tumors for diagnostic and/or therapeutic purposes.

Prognostic prediction across a gradient of total tumor volume in patients with hepatocellular carcinoma undergoing locoregional therapy

Background

The size and number of tumors are important prognostic indicators for hepatocellular carcinoma (HCC). However, it is difficult to assess the prognosis for patients with a variable number and size of tumors. By combining these two factors, we investigated the role and prognostic accuracy of total tumor volume (TTV) for HCC.

Methods

A total of 786 patients undergoing locoregional therapy (transarterial chemoembolization, percutaneous radiofrequency ablation and acetic acid or ethanol injection) for HCC were prospectively evaluated.

Results

The mean and median TTV was 177 cm³ (range, 0.1-3,591 cm³) and 21 cm³, respectively. Of all, 38%, 29%, 15%, 7% and 11% of patients had TTV of <10 cm³, 10-50 cm³, 50-200 cm³, 200-500 cm³ and >500 cm³, respectively. TTV was significantly larger in patients with higher serum α-fetoprotein (AFP) levels or with vascular invasion. The Child-Turcotte-Pugh score, performance status, vascular invasion, AFP level and TTV were significant independent prognostic predictors in the Cox proportional hazards model. After adjustment, patients with TTV 50-200 cm³ (relative risk [RR]: 1.74, p = 0.009), 200-500 cm³ (RR: 2.15, p = 0.006) and >500 cm³ (RR: 3.92, p < 0.001) had a significantly increased mortality risk in comparison to patients with TTV <10 cm³.

Conclusions

TTV is a feasible prognostic predictor across a wide gradient and can be used to predict the mortality risk of HCC. Selecting appropriate cutoffs of TTV may help refine the design of cancer staging system and treatment planning. Future clinical trials of HCC may include this parameter for mortality risk stratification.

Liver resection: a regional hospital experience

BACKGROUND

Liver resection is a significant operation usually limited to large metropolitan hospitals. Liver resections were first performed at the Launceston General Hospital (LGH), a regional centre (bed capacity 280), in May 2000. This is a summary of liver resection at LGH.

METHODS

Data of liver resections performed between May 2000 and March 2008 at LGH were collected retro-prospectively and reviewed with attention to patient survival, post-operative complications and mortality.

RESULTS

There were 102 consecutive liver resections during the study period. Metastatic colorectal adenocarcinoma was the most frequent pathology (n = 61). Six patients had metastases from primaries other than colorectal cancer. There were 13 resections for primary liver malignancy, 2 from invasion by gallbladder carcinoma, 1 for contiguous invasion by gastric cancer and 19 were for benign conditions. Thirteen patients had post-operative wound infections and six had significant bile leaks. There were five deaths in-hospital (surgical mortality 4.9%). At the end of the study period, 51 cancer patients were still alive (14 with disease recurrences) and 30 have died (23 from recurrent diseases). Patients operated for colorectal cancer metastases achieved a 44% 5-year survival rate (median survival = 46 months). Patients with hepatocellular carcinoma had 3-year survival rate of 15% (median survival = 24 months).

CONCLUSION

Resection provides the best hope of cure for patients with primary or secondary hepatic malignancy. With adequate expertise, liver resections can be performed safely in a regional hospital.

Transarterial chemoembolization in patients with hepatocellular carcinoma and renal insufficiency

BACKGROUND

Renal dysfunction is often present in patients with cirrhosis and hepatocellular carcinoma (HCC). Acute renal failure (ARF) may occur after transarterial chemoembolization (TACE) owing to radiocontrast agent. This study investigated the incidence and risk factors of ARF and prognostic predictors in HCC patients with preexisting renal insufficiency undergoing TACE.

METHODS

A total of 566 HCC patients undergoing TACE were enrolled. Renal insufficiency was defined as an estimated glomerular filtration rate less than 60 mL/min/1.73 m.

RESULTS

In a mean follow-up duration of 18+/-16 months, 231 (40.8%) patients undergoing TACE died. Renal insufficiency that was present in 134 (23.7%) patients at baseline, independently predicted a poor prognosis in the Cox proportional hazards model [risk ratio (RR): 1.47, P=0.012]. Of them, 13 (10%) and 6 (5%) patients had transient and prolonged ARF after TACE, respectively. Post-TACE gastrointestinal bleeding [odds ratio (OR): 16.54, P=0.001] and higher Cancer of the Liver Italian Program (CLIP) scores (> or =2; OR: 4.22, P=0.02) were independent risk factors for ARF in the multivariate logistic regression analysis. In the Cox model, prolonged ARF (RR: 3.28, P<0.001) and higher CLIP scores (> or =2; RR: 2.13, P<0.001) were independent poor prognostic predictors for HCC patients with renal insufficiency receiving TACE.

CONCLUSIONS

Gastrointestinal bleeding and higher CLIP scores are associated with the development of ARF in patients with HCC and renal insufficiency undergoing TACE. Higher CLIP scores and renal insufficiency, either preexisting before TACE or as a complication of TACE, are poor prognostic predictors in HCC patients receiving TACE.

Pigment epithelium-derived factor inhibits lysosomal degradation of Bcl-xL and apoptosis in HepG2 cells

Pigment epithelium-derived factor (PEDF) has several biological actions on tumor cells, but its effects are cell-type dependent. The aim of this study was to examine the pathophysiological role of PEDF in hepatocellular carcinoma (HCC). PEDF expression was examined in various hepatoma cell lines and human HCC tissues, and was seen in various hepatoma cell lines including HepG2 cells. In human HCC tissues, PEDF expression was higher than in adjacent non-HCC tissues. In addition, serum PEDF levels were higher in HCC patients than in non-HCC patients, and curative treatment of HCC caused significant reductions in serum PEDF levels compared with pretreatment levels. In vitro experiments, camptothecin (CPT) was used to induce apoptosis and the effect of PEDF was investigated by knockdown of the PEDF gene in CPT-treated HepG2 cells. Knockdown of the PEDF gene enhanced CPT-induced apoptosis, simultaneously down-regulating Bcl-xL expression in HepG2 cells. Expression of apoptosis-related molecules and effects of bafilomycin A1 on CPT-induced apoptosis were also examined in PEDF gene knockdown HepG2 cells. Treatment with bafilomycin A1 suppressed CPT-induced decreases in Bcl-xL expression and increases in apoptosis in PEDF gene knockdown HepG2 cells. PEDF may, therefore, exert anti-apoptotic effects through inhibition of lysosomal degradation of Bcl-xL in CPT-treated HepG2 cells.

Y-90 microshperes in the treatment of unresectable hepatocellular carcinoma

A small percentage of patients with hepatocellular carcinoma (HCC) are candidates for curative treatment in form of resection or transplantation. There are different treatment options for unresectable HCC-like local ablative therapies and recently systemic therapy with Sorafenib. All of these have variable response rate and had been proven to improve survival. In the last few years, there is a growing interest in TheraSphere radioembolization. It consists of yttrium90 (Y-90) embedded into nonbiodegradable glass microspheres. It is selectively administered by intraarterial hepatic injection giving high doses of radiation to the tumor and sparing the liver parenchyma. It has been shown to improve survival and used as a bridge to transplantation and to downstage tumors for resection. Therasphere seems to have favorable safety profile and has been used in patients with portal vein thrombosis with successful outcome.

A phase II study of pemetrexed in patients with advanced hepatocellular carcinoma

Pemetrexed has demonstrated activity in hepatocellular carcinoma (HCC) cell lines, and has a manageable toxicity profile in clinical trials, suggesting its potential as a treatment for HCC patients. A multicenter, Phase II community-based study was conducted to assess the response rate and toxicity profile of single-agent pemetrexed in first-line patients with advanced or metastatic HCC. Patients premedicated with folic acid, vitamin B(12), and dexamethasone were administered pemetrexed 600 mg/m(2) IV on day 1 of each 21-day cycle until disease progression. This nonrandomized study employed Simon's 2-stage design, enrolling 21 eligible patients in the first stage, stopping accrual if < or =2 responders were observed. Responses were four stable disease, 14 progressive disease, and three not evaluable: two had early toxicities (renal/liver failure, sepsis) and one was noncompliant. The most common grade 3 hematological toxicities were neutropenia 6 of 21 (29%) and thrombocytopenia 3 of 21 (14%); with no grade 4 toxicities. Thirteen patients died on-study: 12 PD and one liver failure; none were drug-related. The median survival was 5.2 months (range, <1-12.2). The planned second stage was cancelled, and the trial was closed owing to lack of response. While pemetrexed was tolerated in this patient population, it was not active.