Tumour suppressors in liver carcinogenesis

Reduction of liver tumerogenic effect of N-nitrosodiethylamine by treatment with ɣ-oryzanol in Balb/C mice

In recent years, naturally occurring phytochemicals with antioxidant capacity have generated surmount interest in their therapeutic usage against a wide range of pathological and toxicological conditions. The present study was designed to evaluate potential of ɣ-oryzanol (OZ), a bio-active natural antioxidant against hepatocellular carcinoma effect of the carcinogen N-nitrosodiethylamine in Balb/c mice. OZ inhibited the proliferation of Hep-3B cell line in concentration dependent manner. Administration of OZ to N-nitrosodiethylamine induced Balb/c mice for 16 and 32 weeks showed reduction in levels of liver injury markers, restored the levels of liver tumor markers, suppressed the hepatic nodular incidence and multiplicity, and favorably modulated the liver antioxidant status in a time dependent manner. Histologically, no obvious signs of neoplasia in the liver tissues were observed in OZ supplemented rats with N-nitrosodiethylamine induced liver tumerogenesis. OZ was found to be effective for reduction of N-nitrosodiethylamine induced hepatocellular carcinoma.

Histology-directed matrix-assisted laser desorption/ionization analysis reveals tissue origin and p53 status of primary liver cancers

To date, protein profiles for hepatocellular carcinomas and cholangiocarcinomas have not been systematically evaluated and compared with each other in an unbiased way. Thirty-six hepatocellular carcinomas and adjacent normal tissue samples were analyzed using histology-directed, matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS). Four cholangiocarcinomas and adjacent normal tissue samples were also evaluated. Tissue samples were sectioned at 10 µm, with 1-3 sections thaw-mounted on a conductive indium tin oxide-coated glass slide. Sinapinic acid was manually deposited on areas of each tissue section enriched by epithelial cells, either tumor or normal, and mass spectra were acquired using a MALDI-time of flight instrument. According to class prediction analysis, average prediction accuracy in test sets (composed of 18 hepatocellular carcinoma-normal pairs) ranged from 93.0 to 95.8%. Cholangiocarcinomas and hepatocellular carcinomas had different protein profiles, as evidenced by average prediction accuracy of >95% in the test set for all classifiers. Permutation P-values for 0.632 + bootstrap cross validated misclassification rates (at feature selection P < 0.001) were less than 0.05 for predicting p53 immunostaining status. We conclude that MALDI MS profiles may be useful in assisting with the diagnosis and the differential diagnosis of primary liver cancers.

An update on cholangiocarcinoma associated with primary sclerosing cholangitis

PURPOSE OF REVIEW

Primary sclerosing cholangitis (PSC) is being diagnosed with increasing frequency. The most feared complication is the presence or development of cholangiocarcinoma (CCA). The present review summarizes recent data with regards to diagnosis, pathobiology and treatment.

RECENT FINDINGS

Several investigations have focused on aspects of the molecular biology of CCA in general; such data should be explored now in the context of PSC-related CCA to yield new diagnostic markers and approaches for therapy.

SUMMARY

CCA has to be suspected in any new PSC patient presenting with jaundice. Exploration should include carbohydrate antigen19-9 and two imaging techniques. Endoscopic cholangioscopy might become very rewarding. Important progress has been achieved in liver transplantation by the use of preoperative radio-chemotherapy. Molecular biology points to inflammation-induced cytokines with mutagenic action and to the relevance of extracellular matrix proteins for invasion but also for proliferation. Micro-RNAs prove to be very important in the control of cell proliferation, differentiation and apoptosis. Mutated p53, cyclins, wnt/beta-catenin signaling, proliferation indices, mucins, carbohydrate antigen19-9, CRP and aneuploidy appear to hold significant potential as predictors of outcome in CCA. It is expected that the further unraveling of these molecular processes will ultimately lead to development of tests allowing early diagnosis and to development of medical approaches to retard tumor formation or recurrence following surgical interventions.

p53 immunocytochemistry and TP53 gene mutations in patients with chronic hepatitis C virus (HCV) infection

Chronic infection with hepatitis C virus (HCV) is regarded as a risk factor for hepatocellular carcinoma (HCC), mostly in patients with liver cirrhosis. Present study aimed at evaluation of cellular expression of p53 protein, genetic TP53 changes in liver samples and anti-p53 in serum of patients with chronic hepatitis C virus infection. The expression of p53 protein were analysed by immunocytochemistry in liver biopsies from adult patients with chronic, long-lasting hepatitis C. In order to detect TP53 mutations, PCR/SSCP and sequencing were performed. Antibodies against p53 in serum were determined using enzyme immunoassay (ELISA).In two out of 14 examined patients TP53 point mutations were detected in the liver samples. In the first patient, a substitution of C to T was demonstrated in position 1 of the codon 250, resulting in substitution of proline by serine. The other patient carried a substitution of C to G in position 13274 of the intron 6. The patient carrying mutation in the codon 250 demonstrated morphological traits of liver cirrhosis and had high number of p53-immunoreactive cell nuclei in tissue. None of the patients manifested elevated titres of serum anti-p53. In the liver, significant positive correlations were disclosed between expression of p53 on one hand and grading and staging on the other. A negative correlation was disclosed between cellular expression of p53 and duration time of infection. In conclusions, genetic changes in TP53 can be detected also in non-neoplastic lesions linked to chronic HCV infection.

Targeted therapy for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide. The major etiologies and risk factors for development of HCC are well defined and some steps of hepatocellular carcinogenesis have been elucidated. Despite these scientific advances and the implementation of measures for early detection of HCC in patients who are at risk of this disease, survival of patients has not improved greatly over the past three decades. This situation is partly due to the limited therapeutic options available. While surgery and percutaneous or transarterial interventions are effective for patients with limited or compensated underlying liver disease, more than 80% of patients present with multifocal HCC and/or advanced liver disease, or have comorbidities at the time of diagnosis. Treatment options for these patients have previously been limited to best supportive care. The effectiveness of targeted therapy with monoclonal antibodies or small-molecule kinase inhibitors has now been demonstrated for the treatment of different tumors. In 2007, the multitargeted kinase inhibitor, sorafenib, was found to prolong survival significantly for patients with advanced HCC. This Review discusses the mechanisms of targeted therapies and clinical studies that have investigated these therapies in patients with HCC. Perspectives for future developments are also provided.

S6K1 deficiency protects against apoptosis in hepatocytes

The mammalian target of rapamycin (mTOR)/S6K1 signaling pathway controls cell growth and proliferation. To assess the importance of S6K1 in the balance between death and survival in the liver, we have generated immortalized hepatocyte cell lines from wild-type and S6K1-deficient (S6K1(-/-)) mice. In S6K1(-/-) hepatocytes, caspase-8 and the pro-apoptotic protein Bid were constitutively down-regulated as compared with wild-type. Moreover, S6K1(-/-) hepatocytes failed to respond to the apoptotic trigger of death receptor activation. Neither caspase-8 activation nor FLIP(L) degradation in response to tumor necrosis factor alpha (TNF-alpha) or anti-Fas antibody (Jo2) was observed in cells lacking S6K1. Downstream events such as Bid cleavage, cytochrome C release, caspase-3 activation, DNA laddering, as well as the percentage of apoptotic cells were attenuated as compared with wild-type. In addition, the anti-apoptotic protein Bclx(L) was down-regulated in TNF-alpha-treated or Jo2-treated wild-type hepatocytes, but this response was abolished in S6K1(-/-)cells. In vivo, S6K1-deficient mice were protected against concanavalin A-induced apoptosis. The withdrawal of growth factors strongly induced apoptosis in wild-type, but not in S6K1(-/-) hepatocytes. S6K1 deficiency did not decrease Bclx(L)/Bim ratio on serum withdrawal, thereby protecting cells from cytochrome C release and DNA fragmentation. At the molecular level, the lack of S6K1-mediated negative feedback decreased insulin receptor substrate-1 (IRS-1) serine phosphorylation, resulting in activation of survival pathways mediated by phosphatidylinositol 3-kinase/Akt and extracellular signal-regulated kinase (ERK). However, S6K1(-/-) hepatocytes underwent apoptosis on serum withdrawal in combination with phosphatidylinositol 3-kinase (PI3K) or ERK inhibitors.

CONCLUSION

This finding might explain the mechanism of resistance to mTOR inhibitors in cancer treatments and strongly suggests that the inhibition of S6K1 could protect against acute liver failure and, in combination with inhibitors that abrogate the sustained activation of Akt and ERK, could improve the efficacy of hepatocarcinoma (HCC) treatment.

The prolyl isomerase Pin1 interacts with a ribosomal protein S6 kinase to enhance insulin-induced AP-1 activity and cellular transformation

Phosphorylation of proteins on serine or threonine residues that immediately precede proline (pSer/Thr-Pro) is specifically catalyzed by the peptidyl-prolyl cis-trans isomerase Pin1 and is a central signaling mechanism in cell proliferation and transformation. Although Pin1 is frequently overexpressed in hepatocellular carcinoma (HCC), the molecular mechanism of Pin1 in HCC has not been completely elucidated. Here, we show that Pin1 interacts with p70S6K in vitro and ex vivo. Overexpression of Pin1 resulted in enhanced p70S6K phosphorylation induced by insulin in SK-HEP-1 cells. In contrast, Pin1(-/-) mouse embryonic fibroblasts (MEFs) exhibited significantly decreased insulin-induced p70S6K phosphorylation compared with Pin1(+/+) MEFs. Furthermore, Pin1 enhanced the insulin-induced extracellular signal-regulated protein kinase (ERK)1/2 phosphorylation through its interaction with p70S6K, whereas the inhibition of p70S6K activity by rapamycin suppressed insulin-induced ERK1/2 phosphorylation in SK-HEP-1 cells. Hence, Pin1 affected activator protein-1 activity through p70S6K-ERK1/2 signaling in SK-HEP-1 cells. Most importantly, Pin1-overexpressing JB6 Cl41 cells enhanced neoplastic cell transformation promoted by insulin much more than green fluorescent protein-overexpressing JB6 Cl41 control cells. These results imply that Pin1 amplifies insulin signaling in hepatocarcinoma cells through its interaction with p70S6K, suggesting that Pin1 plays an important role in insulin-induced tumorigenesis and is a potential therapeutic target in hepatocarcinoma.

Evolving therapies in the treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide. The major etiologies and risk factors for HCC development are well defined and some of the steps involved in hepatocarcinogenesis have been elucidated in recent years. Therapeutic options that can be applied in curative or palliative intention are available and are dependent on the HCC stage. The therapeutic options fall into five main categories: (1) surgical interventions, including tumor resection and liver transplantation, (2) percutaneous interventions, including ethanol injection and radiofrequency thermal ablation, (3) transarterial interventions, including embolization and chemoembolization, (4) radiation therapy, and (5) drugs as well as gene and immune therapies. Until recently, no therapy existed for patients with advanced HCC. In 2007 a multikinase inhibitor (sorafenib) showed for the first time a significant increase in overall survival in patients with advanced HCC. Furthermore, several other agents that target different factors of hepatocarcinogenesis (eg, epidermal growth factor, insulin-like growth factors, hepatocyte growth factor, vascular endothelial growth factor, fibroblast growth factor, platelet-derived growth factor, and the transforming growth factors-alpha and -beta), have emerged and been tested in clinical trials. This review gives an overview of the current therapeutic strategies and their clinical impact.

Advances in prevention and diagnosis of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide. The major etiologies and risk factors for HCC development are well defined and some of the steps involved in hepatocarcinogenesis have been elucidated in recent years. Despite these advances and the implementation of measures for early HCC detection as well as novel therapeutic strategies, the survival of patients with HCC has not significantly improved until recently. Therefore, early diagnosis and primary, as well as secondary, prevention are of paramount importance in order to reduce morbidity and mortality from HCC. New technologies, including gene expression profiling and proteomic analyses, should allow further elucidation of the molecular events underlying HCC development and identification of novel diagnostic markers as well as therapeutic and preventive targets.