The clinicopathological and prognostic relevance of cytokeratin 7 and 19 expression in hepatocellular carcinoma. A possible progenitor cell origin

Prognostic indicators for tumor recurrence after liver transplantation in hepatocellular carcinoma and related molecular targeted therapy

Liver transplantation (LT) is a viable therapeutic option for hepatocellular carcinoma (HCC). Many criteria, such as the Milan criteria and the University of California at San Francisco (UCSF) criteria, have been established to select a subset of HCC patients who stand to benefit from LT. However, they are still insufficient for predicting HCC patients at high risk for recurrence and selecting those at low risk. Many molecules which are probable candidates for recognizing HCC patients at high or low risk for recurrence give a wider perspective to consider for LT indication. Besides working as biomarkers, most of them are also functionally involved in some important pathways which contribute to HCC metastasis. The complex network constituted by them shows a multichannel, multistep HCC metastatic process which indicates difficulty in tumor therapy. Given the efficacy of some molecular targeted drugs in the treatment of HCC or prevention of tumor recurrence after LT, the emerging molecular targeted therapy is also discussed in this review.

Immunohistochemical study of hepatocyte, cholangiocyte and stem cell markers of hepatocellular carcinoma

BACKGROUND/PURPOSE

Hepatocellular carcinomas (HCCs) commonly originate from pre-malignant lesions consisting of mature hepatocytes. However, recent studies have suggested that some HCCs emerge from hepatic stem/progenitor cells because stem/progenitor cell markers and cholangiocyte markers are found in these HCCs. At the same time, the expression of stem/progenitor cell markers and cholangiocyte markers may also indicate de-differentiation and transdifferentiation of ordinary HCC cells. This study was performed to help clarify the uncertainty surrounding these HCCs.

METHODS

Sixty-eight surgically resected HCC lesions no larger than 5 cm were studied immunohistochemically using a hepatocyte marker (Hepatocyte), 2 cholangiocyte markers (cytokeratins CK7 and CK19), a marker for mucin (Muc1), and a hepatic stem/progenitor cell marker (C-kit).

RESULTS

Hepatocyte, CK7, CK19, Muc1 and C-kit were positively stained in 68 cases (100%), 51 cases (75.0%), 15 cases (22.1%), 8 cases (11.8%) and 8 cases (11.8%), respectively. In those cases positive for CK7, CK19, Muc1 and C-kit, the positively stained cells formed small foci within a large area of negatively stained cells. Small-sized positive cells suggesting hepatic/stem cell origin were found rarely.

CONCLUSIONS

The positivity of cholangiocyte markers, the stem/progenitor cell marker and mucin production were thought to be due to transdifferentiation of HCC cells rather than malignant transformation of stem/progenitor cells.

Clinicopathological analysis of 14 patients with combined hepatocellular carcinoma and cholangiocarcinoma

BACKGROUND

Combined hepatocellular carcinoma and cholangiocarcinoma (cHCC-CC) is an uncommon subtype of primary hepatic carcinoma, and its prognosis is poor. This study was undertaken to investigate the prognosis and the clinicopathological characteristics of cHCC-CC, including their possible cellular origin.

METHODS

Among 852 patients with a primary hepatic carcinoma who underwent hepatectomy from January 1998 to April 2008 at our hospital, cHCC-CC was identified in 14 patients. The clinicopathological characteristics of the 14 patients were analyzed retrospectively. The expression of the liver stem cell markers (c-kit, CD90, CD133 and CK19) in the tumor tissue was detected by immunohistochemistry, and the Kaplan-Meier method was used to evaluate survival.

RESULTS

Among the 14 patients, 9 presented with abdominal pain, 3 with anorexia and debilitation, and the remaining two patients were asymptomatic. The mean age was 53.6+/-3.0 (range 38-74) years. Among the included patients, 11 had an elevated serum alpha-fetoprotein level, 13 were infected with hepatitis B virus, 9 had vascular invasion and 1 had lymph node metastasis. The average diameter of the tumors was 9.9+/-1.1 (range 5.0-16.0) cm. The median overall survival time was 7.9+/-1.0 months. In addition, the presence of the liver stem cell markers, c-kit, CD90, CD133 and CK19 was 71.4%, 85.7%, 92.9% and 78.6%, respectively. All four markers were simultaneously expressed in eight cases.

CONCLUSIONS

cHCC-CC has aggressive characteristics and the prognosis is extremely dismal. The high expression of liver stem cell markers in the tumor tissue suggests that these tumors may derive from liver stem cells.

Chronic inflammation and hepatocellular carcinoma

Hepatocellular carcinoma (HCC) invariably develops within a setting of chronic inflammation caused by either hepatotropic viruses, toxins, metabolic liver disease or autoimmunity. Mechanisms that link these two processes are not completely understood, but transcription factors of the NF-κB family and signal transducer and activator of transcription 3 (STAT3), cytokines such as IL-6 and IL-1α and ligands of the epidermal growth factor receptor (EGFR) family are clearly pivotal players. HCC may have its origins in either hepatocytes or hepatic progenitor cells (HPCs), and HCCs, like other solid tumours appear to be sustained by a minority population of cancer stem cells.

Gadoxetate disodium-enhanced hepatobiliary phase MRI of hepatocellular carcinoma: correlation with histological characteristics

OBJECTIVE

The purpose of this study was to assess whether gadoxetate disodium-enhanced hepatobiliary phase MRI could predict the histologic factors of hepatocellular carcinomas (HCCs).

MATERIALS AND METHODS

Fifty-three HCCs histopathologically proved by surgery in 51 patients were evaluated retrospectively. All patients underwent gadoxetate disodium-enhanced MRI before surgical resection. The differences in contrast enhancement ratio of the lesions and differences in contrast-to-noise ratio (CNR) among the histologic grades of HCC were compared by using the Kruskal-Wallis test. The Spearman method was used to determine the correlations among contrast enhancement ratio, CNR, cell density ratio, and positivity for anti-hepatocyte antibody, keratin 7, and keratin 19.

RESULTS

Of 53 HCCs, 50 showed low signal intensity on hepatobiliary phase images, whereas three HCCs were hyperintense on hepatobiliary phase images compared with surrounding hepatic parenchyma. Although well-differentiated HCCs tended to show higher contrast enhancement, there was no statistical significance between contrast enhancement ratio of the tumors and histologic grade (p = 0.414). No significant difference was observed between CNR and histologic grade (p = 0.965). The contrast enhancement ratios of the tumors were significantly lower in the keratin 19-positive group than in the keratin 19-negative group (p = 0.015). There was no significant correlation among contrast enhancement ratio, anti-hepatocyte antibody positivity, cell density ratio, and keratin 7 positivity (p > 0.05).

CONCLUSION

The contrast enhancement ratio and CNR of HCCs were not correlated with histologic grades. The contrast enhancement ratio was significantly lower in keratin 19-positive HCCs.

A case of a large cholangiolocellular carcinoma

Cholangiolocellular carcinoma (CoCC) is a rare malignant primary liver tumor that is considered to originate from the canals of Hering, where hepatic progenitor cells are located. CoCC has various clinicopathological findings, therefore it is difficult to describe a clear diagnostic criteria for CoCC. Reported is a case of a large CoCC in a 45-year-old Japanese woman, which could not be preoperatively diagnosed as CoCC. The final diagnosis of CoCC was determined by pathological observation. Since both the biological behavior and diagnostic criteria of CoCC remain unclear, it is necessary to accumulate more information on CoCCs in order to elucidate these characteristic findings.

Fine needle aspiration biopsy of hepatocellular carcinoma and hepatocellular nodular lesions: role, controversies and approach to diagnosis

The role of fine needle aspiration (FNA) biopsy of the liver has evolved. Advances in imaging modalities have obviated the need for tissue confirmation in clinically classic hepatocellular carcinoma (HCC). The risks of needle tract seeding and haematogenous dissemination have been actively debated. Nowadays, cytopathologists are confronted by smaller and smaller nodules, detected due to increased surveillance of high-risk cirrhotic patients. Tissue characterization of small well-differentiated hepatocellular nodular lesions (size less than and equal to 2 cm) is extremely challenging and has therapeutic implications. Major issues in the cytodiagnosis of HCC include: (i) distinguishing benign hepatocellular nodular lesions, namely, large regenerative nodules, dysplastic nodules, focal nodular hyperplasia and hepatocellular adenoma from reactive hepatocytes; (ii) distinguishing well-differentiated HCC from benign hepatocellular nodular lesions; (iii) distinguishing poorly differentiated HCC from intrahepatic cholangiocarcinoma and metastatic carcinomas; (iv) determining the histogenesis of a malignant tumour; and (v) determining the site of origin of a malignant tumour. An overview of the biological evolution and histopathological aspects of dysplastic nodules, small HCCs and 'nodule-in-nodule' lesions is presented in tandem with clinically relevant nomenclature. An algorithmic approach to FNA diagnosis of HCC and hepatocellular nodular lesions is outlined. Optimal results depend on (i) a dedicated radiologist-cytopathologist team; (ii) an on-site cytology service, (iii) a combined cytohistological approach, (iv) immunohistochemistry, and (v) clinicopathological correlation. As we move towards personalized medicine, it is envisaged that hepatic FNA is likely to become a point of care in the management protocol as it takes on the additional role of procurement of tumour and peritumoural tissues for genomic and proteomic profiling to enable targeted molecular therapy.

Fine-needle aspiration biopsy of hepatocellular carcinoma and related hepatocellular nodular lesions in cirrhosis: controversies, challenges, and expectations

The role of hepatic fine-needle aspiration (FNA) biopsy has evolved. Advances in imaging modalities have obviated the need for tissue confirmation in most hepatocellular carcinomas (HCCs). There is risk of needle-tract seeding. Increasingly, small nodules are being detected on ultrasound surveillance of high-risk patients. Diagnostic challenges associated with cirrhosis include distinction of benign hepatocellular nodules, namely, large regenerative nodules and dysplastic nodules, from reactive hepatocytes; and distinction of well-differentiated HCCs from benign hepatocellular nodules. This paper will discuss (i) controversies regarding preoperative/pretransplantation FNA diagnosis of HCC, (ii) update of biological evolution, nomenclature, and histopathologic criteria for diagnosis of precancerous nodules and small HCCs, and (iii) algorithmic approach to FNA diagnosis of hepatocellular nodules. Optimal results depend on dedicated radiologist-cytopathologist team, on-site cytology service; combined cytohistologic approach, immunohistochemistry, and clinicopathologic correlation. Hepatic FNA is likely to be incorporated as a point of care as we move towards personalized medicine.

Advances in understanding the relationship between liver cancer stem cells and metastasis and relapse of liver cancer

Many factors may affect the prognosis of liver cancer, including late diagnosis, cirrhosis, and insensitivity of tumor cells to chemotherapy, and postoperative metastasis and relapse. Previous studies on the metastasis and relapse of liver cancer focused mainly on the migration and shedding of liver cancer cells, adhesion of liver cancer cells to surrounding tissue, and generation of peripheral vessels. The advances in research on liver cancer stem cells (LCSCs) have led to a better understanding of the metastasis and relapse of liver cancer. This paper gives a comprehensive review of LCSCs at the genetic level in terms of their origin and surface markers, signaling pathways involved, and treatment implications.

Contribution of biomarkers and imaging in the management of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most frequent malignant tumour of the liver. HCC prognosis is dependent on the determination of the tumour stage by conventional imaging and early screening. However, patient survival can vary with the same tumour stage. Biomarkers thus have a role in providing an earlier diagnosis, better prognosis classification before treatment and classification prognosis during treatment. In this review article, we will provide a successive, detailed description of the serum, pathological, molecular and imaging markers of HCC.

PET-CT scan is a valuable modality in the diagnosis of fibrolamellar hepatocellular carcinoma: a case report and a summary of recent literature

We report a case of liver cancer with features consistent with fibrolamellar hepatocellular carcinoma (FLHCC) detected by PET-CT scan. A 20-year-old female with a large liver tumor was diagnosed with 'malignant hepatic tumor' 2 years earlier and received five courses of transhepatic arterial chemoembolization (TACE) before she presented to our hospital with abdominal distension and mild pain at the right upper quadrant. Ultrasound and CT scan showed a large tumor in the right lobe of the liver. Contrast CT scan and (18)F-FDG PET-CT showed metastatic lesions in multiple organs. The imaging diagnosis was confirmed by an ultrasound-guided fine needle biopsy of the hepatic lesion which showed features of FLHCC. Immunohistochemical staining showed a marked increase in the expressions of Hepar, CD99, MIB1, proliferating cell nuclear antigen (PCNA), Fibronectin, E-cadherin and CK7. The recent knowledge on the FLHCC and the possible applications of PET-CT were discussed.

Molecular classification of hepatocellular carcinoma anno 2011

Hepatocellular carcinoma has an increasing incidence and high mortality. Treatment options are limited if the disease is not diagnosed in its early stage. The natural course of the disease is aggressive but not always predictable. Molecular profiling is a promising tool for classification in order to optimize prognosis prediction and treatment for an individual patient. In the last decade a large amount of studies has been conducted to better classify hepatocellular carcinomas. The focus of this review is on implications of molecular classification for prognosis and therapeutic decision making in HCC patients. Most studies used microarray technique for genome wide profiling, but other methods to detect genomic changes and microRNA are gaining interest. The whole genome profiling studies identified differences in affected signalling and tried to relate this to prognosis. Some common subgroups were identified, such as the proliferation cluster and the beta-catenin cluster. However, there is still little overlap between most studies. Better study design and bio-informatical analysis might help in this context.

Anatomic pathology of hepatocellular carcinoma: impact on prognosis and response to therapy

A better understanding of signaling pathways in HCC pathogenesis has led to targeted therapies against HCC. Identification of liver cancer stem cell markers and their related pathways is one of the most important goals of liver cancer research. New therapies should ideally target cancer stem cells and not normal stem/progenitor cells, because the latter are very important in regeneration and repair. Individualized HCC therapy will require better definition of patient subgroups that benefit most or should be protected from therapy failure and unwanted side effects. Tumor tissue acquisition should be mandatory, reversing the practice that was established years ago when targeted HCC therapy was but a pipe dream.

Novel therapeutic strategies for targeting liver cancer stem cells

The cancer stem cell (CSC) hypothesis was first proposed over 40 years ago. Advances in CSC isolation were first achieved in hematological malignancies, with the first CSC demonstrated in acute myeloid leukemia. However, using similar strategies and technologies, and taking advantage of available surface markers, CSCs have been more recently demonstrated in a growing range of epithelial and other solid organ malignancies, suggesting that the majority of malignancies are dependent on such a compartment.

Primary liver cancer consists predominantly of hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC). It is believed that hepatic progenitor cells (HPCs) could be the origin of some HCCs and ICCs. Furthermore, stem cell activators such as Wnt/β-catenin, TGF-β, Notch and Hedgehog signaling pathways also expedite tumorigenesis, and these pathways could serve as molecular targets to assist in designing cancer prevention strategies. Recent studies indicate that additional factors such as EpCAM, Lin28 or miR-181 may also contribute to HCC progression by targeting HCC CSCs. Various therapeutic drugs that directly modulate CSCs have been examined in vivo and in vitro. However, CSCs clearly have a complex pathogenesis, with a considerable crosstalk and redundancy in signaling pathways, and hence targeting single molecules or pathways may have a limited benefit for treatment. Many of the key signaling molecules are shared by both CSCs and normal stem cells, which add further challenges for designing molecularly targeted strategies specific to CSCs but sparing normal stem cells to avoid side effects. In addition to the direct control of CSCs, many other factors that are needed for the maintenance of CSCs, such as angiogenesis, vasculogenesis, invasion and migration, hypoxia, immune evasion, multiple drug resistance, and radioresistance, should be taken into consideration when designing therapeutic strategies for HCC.

Here we provide a brief review of molecular signaling in liver CSCs and present insights into new therapeutic strategies for targeting liver CSCs.

CD13: Waving the flag for a novel cancer stem cell target

Cancer stem cells (CSCs) are generally dormant or slowly cycling tumor cells that have the ability to reconstitute tumors. They are thought to be involved in tumor resistance to chemo/radiation therapy and tumor relapse and progression. However, neither their existence nor their identity within many cancers has been well defined. Here, we have demonstrated that CD13 is a marker for semiquiescent CSCs in human liver cancer cell lines and clinical samples and that targeting these cells might provide a way to treat this disease. CD13+ cells predominated in the G0 phase of the cell cycle and typically formed cellular clusters in cancer foci. Following treatment, these cells survived and were enriched along the fibrous capsule where liver cancers usually relapse. Mechanistically, CD13 reduced ROS-induced DNA damage after genotoxic chemo/radiation stress and protected cells from apoptosis. In mouse xenograft models, combination of a CD13 inhibitor and the genotoxic chemotherapeutic fluorouracil (5-FU) drastically reduced tumor volume compared with either agent alone. 5-FU inhibited CD90+ proliferating CSCs, some of which produce CD13+ semiquiescent CSCs, while CD13 inhibition suppressed the self-renewing and tumor-initiating ability of dormant CSCs. Therefore, combining a CD13 inhibitor with a ROS-inducing chemo/radiation therapy may improve the treatment of liver cancer.

Hepatitis B virus infection: A favorable prognostic factor for intrahepatic cholangiocarcinoma after resection

AIM: To study the prognostic factors for intrahepatic cholangiocarcinoma (ICC) and evaluate the impact of chronic hepatitis B virus (HBV) infection on survival rate of ICC patients.

METHODS: A total of 155 ICC patients who underwent macroscopic curative resections (R0 and R1) were enrolled in this retrospective study and divided into group A with HBV infection and group B without HBV infection according to their chronic HBV infection, represented by positive hepatitis B surface antigen (HBsAg) in serum or in liver tissue. Clinicopathological characteristics and survival rate of the patients were evaluated.

RESULTS: All patients underwent anatomical resection. Their 1- and 3-year survival rates were 60.6% and 32.1%, respectively. Multivariate analyses revealed that HBV infection, hepatolithiasis, microscopic satellite lesion, and lymphatic metastasis were the independent prognostic factors for the survival rate of ICC patients. The median disease-free survival time of the patients was 5.0 mo. The number of tumors, microscopic satellite lesion, and vascular invasion were the independent prognostic factors for the disease-free survival rate of the patients. The prognostic factors affecting the survival rate of ICC patients with HBV infection and those without HBV infection were not completely consistent. Alkaline phosphatase > 119 U/L, microscopic satellite lesion, vascular invasion, and lymphatic metastasis were the independent factors for the patients with HBV infection, while r-glutamyltransferase > 64 U/L, microscopic satellite lesion, and poor tumor differentiation were the independent factors for the patients without HBV infection.

CONCLUSION: HBV infection is a valuable clinical factor for predicting tumor invasiveness and clinical outcome of ICC patients. ICC patients with HBV infection should be distinguished from those without HBV infection because they have different clinicopathological characteristics, prognostic factors and outcomes after surgical resection.

MicroRNA-492 is processed from the keratin 19 gene and up-regulated in metastatic hepatoblastoma

MicroRNAs (miRNAs) are well-known regulators of proliferation, apoptosis, and differentiation and are recognized to play an important role in the development of cancers. Here we aimed to identify the functional contribution of miRNAs to the biology of hepatoblastoma (HB), the most common malignant liver tumor in childhood. As overexpression of the oncogene PLAG1 (pleomorphic adenoma gene 1) is a characteristic phenomenon in HB, we used RNA interference and subsequent miRNA array analysis to identify miR-492 as most strongly influenced by PLAG1. We provide novel experimental evidence that miR-492 can originate from the coding sequence of the HB marker gene keratin 19 (KRT19). In agreement with these in vitro observations, significantly elevated levels of coexpressed KRT19 and miR-492 were particularly found in metastatic HB tumor samples. Stable overexpression of miR-492 in HB cell clones served to identify a broad range of differentially expressed transcripts, including several candidate targets of miR-492 predicted by computational algorithms. Among those the liver enzyme BAAT showed significant association with miR-492 expression in HB tumor samples.

CONCLUSION

A close functional relationship between KRT19 and miR-492 was identified that may play an important role in the progression of malignant embryonal liver tumors. Additionally, miR-492 and its associated targets might serve as new HB biomarkers of clinical utility and could assist to explore targeted therapies, especially in metastatic HB with a poor prognosis.

Hepatocellular carcinoma expressing cholangiocyte phenotype is a novel subtype with highly aggressive behavior

BACKGROUND

The pathobiological features and surgical outcomes of patients with classical hepatocellular carcinoma (HCC)-expressing cholangiocyte markers that we named dual-phenotype HCC (DPHCC) remain unclear. The purpose of this study was to assess the association between the phenotype and surgicopathologic features of DPHCC.

METHODS

A retrospective single-center study was performed on the surgicopathologic features of DPHCC from 1530 consecutive surgical specimens. Immunohistochemical staining was performed with antibodies to hepatocytes (Hep Par 1/pCEA) and cholangiocytes (cytokeratin 19 [CK19]/mucin core protein-1 [MUC-1]).

RESULTS

DPHCC accounted for 10.1% (n = 155) of total HCCs. The serum alfa-fetoprotein and CA19-9 were elevated in 87.7% (n = 136) and 20.7% (n = 32) of patients, respectively; the former had close correlation with the immunostaining of CK19 (P < 0.01). The combination of immunostaining intensities of CK19 and MUC-1 was significantly associated with tumor size, microvascular invasion, and satellite nodule formation (P < 0.05-0.01). Compared to patients with pure HCC, those with DPHCC had significantly lower overall survival (30.4 ± 3.7 vs. 43.6 ± 3.9 months, P < 0.05) and recurrence-free survival (13.2 ± 2.0 vs. 23.4 ± 2.5 months, P < 0.01), respectively. Multivariate Cox regression analyses identified CK19-positive expression to be an independent prognostic factor for both overall survival and recurrence-free survival.

CONCLUSIONS

DPHCC is a novel surgicopathologic entity that has a highly aggressive behavior and worse postoperative prognosis than pure HCC. Because the morphological features between DPHCC and conventional HCC overlap, we recommend that CK19 be routinely used in the pathological diagnosis of HCC for screening DPHCC.

Epidermal growth factor induces cytokeratin 19 expression accompanied by increased growth abilities in human hepatocellular carcinoma

Cytokeratin (CK) 19-positive hepatocellular carcinoma (HCC) has been reported to have a poor prognosis. The mechanism of the development of CK19-positive HCC remains to be studied. To clarify this, in vitro experiments were performed using human HCC cell lines (PLC-5, HepG2), and the phenotypic changes after stimulation with several growth factors were examined using quantitative reverse transcriptase PCR, western blotting, and immunofluorescence staining. In vivo experiments using human HCC specimens obtained from a total of 78 patients and clinicopathological analysis were also performed. Among the growth factors tested, epidermal growth factor (EGF) had prominent effects on inducing CK19 expression in PLC-5 and HepG2, which was accompanied by the reduced expression of α-fetoprotein in PLC-5. The induction of CK19 expression after EGF stimulation was accompanied by the phosphorylation of c-Jun-N-terminal kinase (JNK)/stress-activated protein kinase, which was blocked by the addition of JNK inhibitors. EGF also increased proliferative abilities and invasive properties of the HCC cell lines. In vivo, 9 (12%) of 78 HCC cases showed positive immunohistochemical staining of CK19. The extent of positive immunohistochemical signals of EGF, EGF receptor (EGFR), and JNK expression was significantly intense in CK-19-positive HCC than those of CK19-negative HCC. Clinicopathological analysis showed that CK19-positive HCC had a high incidence of portal vein invasion, extrahepatic metastasis and an early relapse, which was associated with the worsened 2-year disease free survival. These results indicate that the activation of the EGF-EGFR signaling pathway is associated with the development of CK19-positive HCC, and the EGF-induced increase in growth abilities of HCC may account for the poor prognosis of the patients.

Liver transplantation for hepatocellular carcinoma: the impact of human immunodeficiency virus infection

Liver transplantation (LT) has become an accepted therapy for end-stage liver disease in human immunodeficiency virus-positive (HIV+) patients, but the specific results of LT for hepatocellular carcinoma (HCC) are unknown. Between 2003 and 2008, 21 HIV+ patients and 65 HIV- patients with HCC were listed for LT at a single institution. Patient characteristics and pathological features were analyzed. Univariate analysis for overall survival (OS) and recurrence-free survival (RFS) after LT was applied to identify the impact of HIV infection. HIV+ patients were younger than HIV- patients [median age: 48 (range = 41-63 years) versus 57 years (range = 37-72 years), P < 0.001] and had a higher alpha-fetoprotein (AFP) level [median AFP level: 16 (range = 3-7154 μg/L] versus 13 μg/L (range = 1-552 μg/L), P = 0.04]. There was a trend toward a higher dropout rate among HIV+ patients (5/21, 23%) versus HIV- patients (7/65, 10%, P = 0.08). Sixteen HIV+ patients and 58 HIV- patients underwent transplantation after median waiting times of 3.5 (range = 0.5-26 months) and 2.0 months (range = 0.5-24 months, P = 0.18), respectively. No significant difference was observed in the pathological features of HCC. With median follow-up times of 27 (range = 5-74 months) and 36 months (range = 3-82 months, P = 0.40), OS after LT at 1 and 3 years reached 81% and 74% in HIV+ patients and 93% and 85% in HIV- patients, respectively (P = 0.08). RFS rates at 1 and 3 years were 69% and 69% in HIV+ patients and 89% and 84% in HIV- patients, respectively (P = 0.09). In univariate analysis, HIV status did not emerge as a prognostic factor for OS or RFS.

CONCLUSION

Because of a higher dropout rate among HIV+ patients, HIV infection impaired the results of LT for HCC on an intent-to-treat basis but had no significant impact on OS and RFS after LT.

Role of p53 and β-catenin mutations in conjunction with CK19 expression on early tumor recurrence and prognosis of hepatocellular carcinoma

BACKGROUND

Cytokeratin 19 (CK19), a molecular marker of hepatic progenitor cells and cholangiocytes, is expressed in hepatocellular carcinomas (HCC), but not in normal hepatocytes. However, role of CK19 in HCC progression, especially when interacted with p53 and β-catenin mutations, remained largely unknown.

MATERIALS AND METHODS

From January 1983 to December 1997, 210 surgically resected, unifocal, primary HCCs were studied retrospectively. CK19 protein expression was detected by immunohistochemistry while mutations of p53 and β-catenin genes were detected by direct DNA sequencing.

RESULTS

CK19 protein expression was detected in 35.7% (75/210), p53 mutation in 47.2% (83/176) and β-catenin mutation in 14.5% (27/186). The tumor size (p=0.0023), grade (p  = 0.00093), tumor stage (p  = 4  x  10-7), high α-fetoprotein (p=0.0004), p53 mutation (p  = 0.024), absence of β-catenin mutation (p  =  0.0013), and CK19 expression (p  =  3 x 10-5) were markers predictive of early tumor recurrence (ETR). CK19 expression, stage, and ETR were strong indicators of poor prognosis (all p  <  0.0001). Importantly, combination analysis showed an additive unfavorable prognostic interaction of CK19 expression and p53 mutation. On the contrary, concurrent CK19 expression and β-catenin mutation was rare and CK19 expression abolished the suppression effect of β-catenin mutation on HCC progression.

CONCLUSIONS

CK19 expression is associated with more aggressive HCC. CK19 cooperates with p53 mutation towards advanced disease. In contrast, CK19 expression and β-catenin mutation play dramatic opposite roles in vascular invasion, ETR and the prognosis of HCC.

Cytokeratin expression as an aid to diagnosis in medical liver biopsies

The study of cytokeratin expression has provided a valuable insight into the biliary microanatomy of the liver in health and disease. The canals of Hering are a putative site of origin for progenitor cells, which may repopulate the liver after cellular damage and loss. Normal bile ducts and the bile ductular reaction that occurs in many chronic liver diseases - especially chronic biliary tract disease - express cytokeratin (CK) 7 and CK19. Therefore, both ductopenia and the process of bile ductular reaction can be highlighted with immunohistochemistry for these cytokeratins. Furthermore, CK7 is usually expressed in an increasingly widespread manner by hepatocytes as chronic cholestatic liver disease progresses. For these reasons, CK immunohistochemistry is a very useful adjunct to morphological assessment and histochemical stains for copper retention when a diagnosis of chronic biliary disease is being considered. This review describes the anatomical theory behind the use of CK immunohistochemistry for the assessment of bile duct number and distribution in the liver and provides practical advice for the application of this technique in the diagnostic setting of common medical liver diseases.

Stem cells in cancer: instigators and propagators?

There is growing realization that many - if not all - cancer-cell populations contain a subpopulation of self-renewing stem cells known as cancer stem cells (CSCs). Unlike normal adult stem cells that remain constant in number, CSCs can increase in number as tumours grow, and give rise to progeny that can be both locally invasive and colonise distant sites - the two hallmarks of malignancy. Immunodeficient mouse models in which human tumours can be xenografted provide persuasive evidence that CSCs are present in human leukaemias and many types of solid tumour. In addition, many studies have found similar subpopulations in mouse tumours that show enhanced tumorigenic properties when they are transplanted into histocompatible mice. In this Commentary, we refer to CSCs as tumour-propagating cells (TPCs), a term that reflects the assays that are currently employed to identify them. We first discuss evidence that cancer can originate from normal stem cells or closely related descendants. We then outline the attributes of TPCs and review studies in which they have been identified in various cancers. Finally, we discuss the implications of these findings for successful cancer therapies.

Tumor initiation and progression in hepatocellular carcinoma: risk factors, classification, and therapeutic targets

Hepatocellular carcinoma (HCC) is a major health problem worldwide responsible for 500 000 deaths annually. A number of risk factors are associated with either the induction of the disease or its progression; these include infection with hepatitis B or C virus, alcohol consumption, non-alcoholic steatohepatitis and certain congenital disorders. In around 80% of the cases, HCC is associated with cirrhosis or advanced fibrosis and with inflammation and oxidative stress. In this review we focus firstly on the different risk factors for HCC and summarize the mechanisms by which each is considered to contribute to HCC. In the second part we look at the molecular processes involved in cancer progression. HCC development is recognized as a multistep process that normally develops over many years. Over this period several mutations accumulate in the cell and that stimulate malign transformation, growth, and metastatic behavior. Over the recent years it has become evident that not only the tumor cell itself but also the tumor microenviroment plays a major role in the development of a tumor. There is a direct link between the role of inflammation and cirrhosis with this microenviroment. Both in vitro and in vivo it has been shown that tumor formation and metastatic properties are linked to epithelial-mesenchymal transition (EMT), a process by which facillitates the tumor cell's attempts to migrate to a more favourable microenviroment. Several groups have analyzed the gene expression in HCC and its surrounding tissue by microarray and this has resulted in the molecular classification into a distinct number of classes. Here we also found a role for hypoxia induced gene expression leading to a clinically more aggressive gene expression in HCC. Molecular analysis also helped to identify important cellular pathways and possible therapeutic targets. The first molecule that in this way has shown clinical application for liver cancer is the multikinase inhibitor sorafenib, others are currently in different stages of clinical studies like the mTOR inhibitor everolimus.

Hepatic progenitor cells: an update

Liver progenitor cells are activated in most human liver diseases. The dynamics, and therefore subpopulations, of progenitor cells are, however, different in acute versus chronic hepatocytic diseases and in biliary diseases. The role of Wnt and Notch signaling pathways in activation and differentiation of human hepatic progenitor cells holds great promise because they can be manipulated by drugs. Hepatocytic differentiation requires inhibition of Notch (numb switched on), whereas cholangiocytic differentiation requires Notch activation. In this way, the patients' own regenerative response could be supported, which could eventually even avoid the need for transplantation in several patients.

The use of immunohistochemistry in liver tumors

A variety of benign and malignant neoplasms can be encountered in the liver. Hematoxylin and eosin-stained tissue sections alone may not yield sufficient information to definitively diagnose liver tumors; therefore, ancillary studies with immunohistochemical markers can play a crucial role in differentiating the different hepatic neoplasms. The recent development of oncofetoprotein glypican-3 has added to the value of immunohistochemistry in diagnosing liver cancer. This review discusses the immunohistochemical markers used most often in the diagnosis of hepatic tumors.

Primary isolated hepatic oval cells maintain progenitor cell phenotypes after two-year prolonged cultivation

BACKGROUND & AIMS

Although expandable hepatic progenitors provide renewable cell sources for treatment of hepatic disorders, long-term cultivation of hepatic progenitors may affect proliferation and differentiation abilities, and even initiate the formation of malignant cancer stem cells. This study aims to determine characteristics of primary cultured hepatic oval cells after prolonged cultivation in vitro.

METHODS

Hepatic oval cells isolated from rats fed with a choline-deficient, ethionine-supplemented diet were continuously propagated every 5-7 days, to 100 passages over two years. Hepatocytic differentiation was induced by sodium butyrate and characterized using western blot, periodic acid Schiff assays, albumin secretion and urea production. Proliferation capacity was evaluated using growth-curve and cell-cycle analysis; anchorage-independent growth and tumorigenicity were determined using soft agar and xenograft assay.

RESULTS

After 2 years of serial passages, hepatic oval cells with typical epithelial morphology continuously expressed OV-6, BD-1, BD-2, and Dlk as markers for hepatic progenitors, cytokeratin 19 as a cholangiocyte marker, and alpha-fetoprotein and albumin as hepatocyte markers. Furthermore, sodium butyrate could induce these cells to become glycogen-storage cells with the functions of albumin secretion and ureagenesis from ammonia clearance, indicating hepatocytic differentiation. Although proliferation slightly accelerated after the 50th passage, hepatic oval cells stayed diploid cells with features of chromosomal stability, which did not acquire anchorage-independent growth capacity and caused no tumor in immunodeficient mice, suggesting no spontaneous malignant transformation.

CONCLUSIONS

Hepatic oval cells retain the progenitor cell features without spontaneous malignant transformation after prolonged cultivation, and thus may serve as an expandable cell source for future exploitation of stem cell technology.

Tolerance and outcome of patients with unresectable hepatocellular carcinoma treated with sorafenib

BACKGROUND

Sorafenib is the standard treatment for patients with an advanced stage of hepatocellular carcinoma (HCC). The aims of this study were (i) to evaluate the tolerance and survival of sorafenib-treated patients, in a nonselected population, especially in Child-Pugh B patients; and (ii) to identify potential prognostic factors of survival.

PATIENTS AND METHODS

From April 2007 to December 2008, 50 patients received sorafenib for advanced HCC. Seventeen (34%) were Child-Pugh B patients. We recorded adverse events and the duration of treatment and survival. For 34 patients with histopathologically proven HCC, immunophenotypical analysis was carried out using antibodies against cluster differentiation 34, vascular endothelial growth factor, phosphorylated ERK, cytokeratin 19, and phosphorylated stat3.

RESULTS

Patients with Child-Pugh B cirrhosis had a more advanced stage of the disease compared with Child-Pugh A patients. The occurrence of adverse events was similar in Child-Pugh A and Child-Pugh B patients. Duration of treatment until discontinuation for bad tolerance was lower in Child-Pugh B patients (1.8 vs. 5 months, P=0.02). Survival of Child-Pugh A patients was higher compared with Child-Pugh B patients (8.9 vs. 2 months, P=0.004). Barcelona Clinic Liver Cancer stage, Eastern Cooperative Oncology Group Performance Status, portal vein impairment, extra-hepatic spread, and alpha-foetoprotein were also prognostic factors. In multivariate analysis, the sole factor associated with survival was the Barcelona Clinic Liver Cancer stage. None of the immunohistological markers used was associated with tolerance and survival.

CONCLUSION

Occurrence of adverse events is similar in Child-Pugh A and Child-Pugh B patients. Nevertheless, the survival of Child-Pugh B patients is very low. Whether liver function or tumor spread is responsible for mortality is unclear. Opportunity of treatment for Child-Pugh B patients is questionable. The immunophenotype of tumoral tissue was not predictive of survival.

Fibrolamellar carcinoma of the liver exhibits immunohistochemical evidence of both hepatocyte and bile duct differentiation

Fibrolamellar carcinoma is a rare malignant primary liver neoplasm with characteristic histological features that typically arises in young patients without viral hepatitis or cirrhosis. Previous studies on this entity have been limited by small numbers of patients. In contrast to classical hepatocellular carcinoma, individual cases of fibrolamellar carcinoma have been reported to express cytokeratin 7. In addition, ultrastructural and serological studies have suggested that fibrolamellar carcinoma may show neuroendocrine differentiation. The cellular differentiation of fibrolamellar carcinoma has not been studied and little is reported about its immunohistochemical profile. We studied 26 cases of fibrolamellar carcinoma and 62 cases of classical hepatocellular carcinoma by immunohistochemistry for HepPar1, glypican-3, pCEA, CD10, alpha-fetoprotein, cytokeratin 20, neuroendocrine markers, and surrogate markers for biliary differentiation (cytokeratin 7, cytokeratin 19, epithelial membrane antigen, EpCAM, mCEA, B72.3, and CA19.9). In situ hybridization for albumin mRNA was also performed. Tumor cells of fibrolamellar carcinoma and hepatocellular carcinoma showed positive signals for albumin mRNA by in situ hybridization in all cases. Both tumor types stained uniformly positively with HepPar1 and most showed a canalicular staining pattern for pCEA, confirming their hepatocellular differentiation. In addition, 39% of hepatocellular carcinoma cases and 59% of fibrolamellar carcinoma cases were positive for glypican-3. All 22 fibrolamellar carcinoma cases tested showed positive staining for cytokeratin 7 and epithelial membrane antigen, whereas less than one-third of hepatocellular carcinoma cases were positive for these markers (P<0.0001). Further, 36% of fibrolamellar carcinoma cases showed staining for B72.3, cytokeratin 19, EpCAM, or mCEA. Minimal evidence of neuroendocrine differentiation in either tumor was found with any of the usual immunohistochemical markers used for this purpose. Therefore, cytokeratin 7 and epithelial membrane antigen may be useful to differentiate between fibrolamellar carcinoma and hepatocellular carcinoma. On the basis of immunohistochemistry, fibrolamellar carcinoma seems to show both hepatocellular and bile duct differentiation.

Pathology of combined hepatocellular-cholangiocarcinoma

Combined hepatocellular-cholangiocarcinoma is a rare primary neoplasm in the liver. It has gained increasing recognition recently, which in part may be due to more extensive sampling of the explants and surgical resection specimens, the diagnostic challenges encountered in the clinical practice, and the yet to be determined clinical outcome, but partly may be attributed to its intriguing histogenesis/cells of origin. This review aims to update combined hepatocellular-cholangiocarcinoma with an emphasis on the pathological diagnosis, including the differential diagnosis and its diagnostic pitfalls, the possible cell of origin of this neoplasm, and its clinical outcome.

Hepatocellular carcinoma in individuals with HBV infection or HBV-HCV co-infection in a low endemic country

OBJECTIVE

The aim of this nationwide cohort study was to assess the risk for hepatocellular carcinoma (HCC) in patients with chronic hepatitis B virus (HBV) infection or HBV and hepatitis C virus (HCV) co-infection in Sweden, a low endemic country.

MATERIAL AND METHODS

A total of 12,080 patients with HBV and 3238 patients with HBV-HCV co-infection were notified to the Swedish institute for Infectious Disease Control between 1990 and 2004. After excluding 1850 patients with acute HBV and 584 patients infected in adult life, we analyzed the cohort of 9646 subjects with chronic HBV infection. In the co-infection cohort, 1697 patients were analyzed after excluding 1541 cases with acute HBV. The Swedish national cancer registry was used for follow-up. The HCC incidence rate in the cohorts was compared with the HCC incidence rate in the general population and the standardized incidence ratio (SIR) was calculated for different strata according to estimated infection period.

RESULTS

HCC was found in 45 patients in the HBV cohort. In the stratum of 40-49 years of infection we found a SIR of 47 and in stratum 50-59 years the SIR was 54. In the co-infected cohort 10 HCCs were found. The SIR in the stratum 20-29 years of infection was 34 and the SIR in the stratum 30 years and over was 91.

CONCLUSIONS

This national cohort study of HBV infected and HBV-HCV co-infected subjects in a low endemic country confirms a highly increased risk of liver cancer compared to the general population.

Molecular diagnosis of multistage hepatocarcinogenesis

Human hepatocellular carcinoma is recognized as a good model for multistage carcinogenesis, as the malignant steps from chronic liver disease through to advanced human hepatocellular carcinoma are relatively clear. We address the activation of different molecular pathways during hepatocarcinogenesis that is especially useful in the diagnosis of pathological multistage human hepatocellular carcinoma. In chronic liver disease, the gene-expression signature as well as the degree of liver fibrosis could help us to predict the development of human hepatocellular carcinoma or survival outcome after treatment for human hepatocellular carcinoma. Several genes, such as HSP70, CAP2 and GPC3, have been identified as potential biomarkers for early human hepatocellular carcinoma. Classical oncogenes or tumor suppressor genes, such as beta-catenin and p53, are mutated during the progression from early to advanced human hepatocellular carcinoma. Also, the presence of hepatoblastic feature like CK19 in advanced human hepatocellular carcinoma can be used as a predictor of aggressive human hepatocellular carcinoma. Although many advances have been made in the diagnosis of multistage hepatocarcinogenesis, we still need further useful markers to more precisely evaluate each step of hepatocarcinogenesis for better treatment choices, and that will promote future molecular-targeted therapy.

Histopathological classification of hepatocellular carcinoma

Recent advances in the understanding of HCC heterogeneity have shown not only distinct molecular classes with potential therapeutical implications but also have suggested that subclasses might be mirrored by tumour morphology and phenotype. The classification of HCC is therefore shifting from a more traditional, morphology-based approach to a more functional approach with clinical implications. The classical histological patterns (trabecular, pseudoglandular, solid, etc.) are still taken into account but in combination with other parameters such as cell grading, clonal changes, type and extent of vascularisation, tumour immunophenotype etc. This array of morpho-phenotypical features is expected to ultimately provide information about cell of origin, tumour behaviour and, hopefully, treatment sensitivity. In this chapter we will give a brief overview on modern principles of hepatic carcinogenesis by outlining the events/lesions bridging the microscopic dysplasia to advanced HCC. In this context special emphasis will be given to novel concepts and diagnostics and differential diagnosis of small HCC (of early and progressed type), which is the main target of the surveillance in the cirrhotic population. Novel and emerging subpopulations of HCC will also be considered, for example HCC with stem/progenitor cell phenotype and mixed hepatobiliary forms which are filling the traditional separation between two entities (HCC and cholangiocarcinoma), likely more inter-related than previously thought.

Intermediate hepatobiliary cells predict an increased risk of hepatocarcinogenesis in patients with hepatitis C virus-related cirrhosis

BACKGROUND & AIMS

The expression of biliary lineage markers such as cytokeratin (K) 7 by hepatocytes is thought to reflect an altered regeneration pathway recruiting a stem cell compartment, more prone to carcinogenesis. We aimed to investigate the presence of these so-called intermediate hepatobiliary cells (IHC) in liver biopsies of patients with hepatitis C-related cirrhosis and their potential influence on the subsequent occurrence of hepatocellular carcinoma (HCC).

METHODS

From a cohort of patients with hepatitis C-related cirrhosis, prospectively screened for HCC, we retrospectively selected those with a liver biopsy performed for the initial diagnosis of cirrhosis. Presence of IHC was recorded when foci of K7-positive, intermediate-sized hepatocytes were detected.

RESULTS

A total of 150 patients were included (87 men; mean age, 57 y; range, 19-84 y; body mass index, 25 kg/m(2)). After a median follow-up period of 4.85 years, HCC was diagnosed in 36 patients (24%). Baseline liver biopsy showed intermediate hepatobiliary cell foci in 61 patients (41%). Intermediate cells co-expressed both hepatocytes markers and the progenitor cell markers Ep-CAM and K19. The presence of intermediate hepatobiliary cells was associated independently with HCC occurrence (Fine and Gray model; hazard ratio, 2.48; 95% confidence interval, 1.24-4.96; P = .01). Other predictors of HCC were diabetes and low platelet count. The HCC annual incidence rate was significantly higher in patients with IHC compared with patients without (8.14% vs 3.12%, Gray's test, P = .003).

CONCLUSIONS

The aberrant expression of biliary K by hepatocytes in patients with hepatitis C virus-related cirrhosis is related independently to HCC occurrence.

Biomarkers for prediction of metastasis and recurrence of hepatocellular carcinoma

The metastasis of hepatocellular carcinoma (HCC) has long been recognized as a multi-step process that involves multiple factors. Instead of diagnostic models based on single-molecule detection, the combination of multiple molecules will be the trend for early tumor diagnosis or prediction of tumor metastasis and recurrence. Many differentially expressed metastasis-associated genes and proteins have been reported in HCC. This article gives an overview of protein biomarkers for prediction of HCC metastasis and recurrence.

Fibrolamellar Hepatocellular Carcinoma: An Immunohistochemical Comparison With Conventional Hepatocellular Carcinoma

The fibrolamellar variant of hepatocellular carcinoma (FLC) differs from conventional hepatocellular carcinoma (HCC) in some clinical and pathological features. The authors investigated possible differences in reactivity between FLCs and HCCs using glypican-3 (GPC3), an oncofetal protein, and survivin, an antiapoptotic protein. They also compared staining of FLC and HCC with antibodies to cytokeratins 7 (CK7) and 19 (CK19) and CD34. GPC3 was significantly more often and more strongly expressed in HCCs (72%) than in FLCs (17%). Survivin nuclear translocation in tumor cells did not differ between HCCs (10%) and FLCs (9%). There was more abundant expression of CK7 in FLCs (92%) than in HCCs (33%), whereas CK19 was more often found in HCCs (20%) than in FLCs (5%). All tumors had CD34-positive sinusoids. This study shows that FLCs and HCCs differ in the expression of GPC3, CK7, and CK19 and that there is a lack of difference as regards survivin and CD34.

Identification of a cholangiocarcinoma-like gene expression trait in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) and cholangiocarcinoma (CC) are the major adult liver cancers. The existence of combined hepatocellular-cholangiocarcinoma (CHC), a histopathologic intermediate form between HCC and CC, suggests phenotypic overlap between these tumors. Here, we applied an integrative oncogenomic approach to address the clinical and functional implications of the overlapping phenotype between these tumors. By performing gene expression profiling of human HCC, CHC, and CC, we identified a novel HCC subtype, i.e., cholangiocarcinoma-like HCC (CLHCC), which expressed cholangiocarcinoma-like traits (CC signature). Similar to CC and CHC, CLHCC showed an aggressive phenotype with shorter recurrence-free and overall survival. In addition, we found that CLHCC coexpressed embryonic stem cell-like expression traits (ES signature) suggesting its derivation from bipotent hepatic progenitor cells. By comparing the expression of CC signature with previous ES-like, hepatoblast-like, or proliferation-related traits, we observed that the prognostic value of the CC signatures was independent of the expression of those signatures. In conclusion, we suggest that the acquisition of cholangiocarcinoma-like expression traits plays a critical role in the heterogeneous progression of HCC.

The use of Cytokeratin 19 (CK19) immunohistochemistry in lesions of the pancreas, gastrointestinal tract, and liver

Cytokeratin immunostaining forms the bedrock of the immunohistochemical evaluation of tumors. Cytokeratin 19 (CK19) belongs to a family of keratins, which are normally expressed in the lining of the gastroenteropancreatic and hepatobiliary tracts. CK19 immunohistochemistry has been used successfully in thyroid tumors to recognize papillary carcinomas for some time. However, its use in the pancreas, liver, and gastrointestinal tract (GIT) has only recently come to the fore. The purpose of this review is to look at the use of CK19 immunohistochemistry in tumors occurring at these sites. CK19 has been shown to be an independent prognostic factor for pancreatic neuroendocrine tumors, especially the insulin-negative tumors. CK19 positive tumors are associated with poor outcome irrespective of the established pathologic parameters such as size, mitoses, lymphovascular invasion, and necrosis. It is recommended that CK19 be part of the immunohistochemical panel in the work-up of pancreatic endocrine tumors. CK19 is positive in the most of neuroendocrine tumors occurring in the rest of the GIT, except rectal tumors, which are negative. In the liver, CK19 is of prognostic value in hepatocellular carcinomas and is of use in distinguishing cholangiocarcinoma from hepatocellular carcinomas. It can also be used to highlight native ductules in the liver and helps separate conditions such as focal nodular hyperplasia from hepatic adenoma. The vast majority of adenocarcinomas in the GIT and pancreas are CK19 positive.

Progenitor-derived hepatocellular carcinoma model in the rat

Human hepatocellular carcinoma (HCC) is a heterogeneous disease of distinct clinical subgroups. A principal source of tumor heterogeneity may be cell type of origin, which in liver includes hepatocyte or adult stem/progenitor cells. To address this issue, we investigated the molecular mechanisms underlying the fate of the enzyme-altered preneoplastic lesions in the resistant hepatocyte (RH) model. Sixty samples classified as focal lesions, adenoma, and early and advanced HCCs were microdissected after morphological and immunohistochemical evaluation and subjected to global gene expression profiling. The analysis of progression of the persistent glutathione S-transferase (GSTP)(+) focal lesions to fully developed HCC showed that approximately 50% of persistent nodules and all HCCs expressed cytokeratin 19 (CK19), whereas 14% of remodeling nodules were CK19(+). Unsupervised hierarchical clustering of the expression profiles also grouped the samples according to CK19 expression. Furthermore, supervised analysis using the differentially expressed genes in each cluster combined with gene connectivity tools identified 1308 unique genes and a predominance of the AP-1/JUN network in the CK19(+) lesions. In contrast, the CK19-negative cluster exhibited only limited molecular changes (156 differentially expressed genes versus normal liver) consistent with remodeling toward differentiated phenotype. Finally, comparative functional genomics showed a stringent clustering of CK19(+) early lesions and advanced HCCs with human HCCs characterized by poor prognosis. Furthermore, the CK19-associated gene expression signature accurately predicted patient survival (P < 0.009) and tumor recurrence (P < 0.006).

CONCLUSION

Our data establish CK19 as a prognostic marker of early neoplastic lesions and strongly suggest the progenitor derivation of HCC in the rat RH model. The capacity of CK19-associated gene signatures to stratify HCC patients according to clinical prognosis indicates the usefulness of the RH model for studies of stem/progenitor-derived HCC.

Hepatic cancer stem cells and drug resistance: Relevance in targeted therapies for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of most common malignancies in the world. Systemic treatments for HCC, particularly for advanced stages, are limited by the drug resistance phenomenon which ultimately leads to therapy failure. Recent studies have indicated an association between drug resistance and the existence of the cancer stem cells (CSCs) as tumor initiating cells. The CSCs are resistant to conventional chemotherapies and might be related to the mechanisms of the ATP Binding Cassette (ABC) transporters and alterations in the CSCs signaling pathways. Therefore, to contribute to the development of new HCC treatments, further information on the characterization of CSCs, the modulation of the ABC transporters expression and function and the signaling pathway involved in the self renewal, initiation and maintenance of the cancer are required. The combination of transporters modulators/inhibitors with molecular targeted therapies may be a potent strategy to block the tumoral progression. This review summarizes the association of CSCs, drug resistance, ABC transporters activities and changes in signaling pathways as a guide for future molecular therapy for HCC.

Primary liver tumors: origin and target therapy

BACKGROUND

The liver is the largest gland and chief metabolic organ of the human body possessing a unique ability to regenerate. The general interest of primary liver tumors is noteworthy because of their increasing worldwide incidence and mortality. Recent studies have focused on the ancestors of mature hepatocytes, which are capable of proliferating, differentiating and self-renewing.

OBJECTIVE

To provide a brief and up-to-date review on the cellular origin of primary liver tumors and to examine the use of stem cells in potential future therapeutic attempts.

METHODS

A review of relevant literature.

RESULTS

It is clear that hepatic progenitor cells (HPCs) could be the basis of some hepatocellular carcinomas (HCC), cholangiocarcinomas (CHC), hepatocellular adenomas and hepatoblastomas. Cancer stem cell (CSC) theory emphasizes the role of hepatic stem cells in the development and progression of liver tumors.

CONCLUSION

The expression of HPCs markers may be used as new independent prognostic factors in HCC. Conventional treatments for HCC do not seem to be beneficial for the majority of patients and new therapeutic approaches such as gene therapy and targeted drug therapy are of great clinical interest.

Keratin 19 marks poor differentiation and a more aggressive behaviour in canine and human hepatocellular tumours

Background

The expression of Keratin 19 (K19) was reported in a subset of hepatocellular carcinomas (HCCs). K19 positive HCCs are associated with an increased malignancy compared to K19 negative HCCs. No suitable mouse models exist for this subtype of HCC, nor is the incidence of K19 expression in hepatocellular neoplasia in model animals known. Therefore, we compared the occurrence and tumour behaviour of K19 positive hepatocellular neoplasias in dog and man.

Results

The expression of hepatocellular differentiation (HepPar-1), biliary/progenitor cell (K7, K19), and malignancy (glypican-3) markers was semi-quantitatively assessed by immunohistochemistry. The histological grade of tumour differentiation was determined according to a modified classification of Edmondson and Steiner; the staging included intrahepatic, lymph node or distant metastases. Four of the 34 canine hepatocellular neoplasias showed K19 positivity (12%), of which two co-expressed K7. K19 positive tumours did not express HepPar-1, despite the histological evidence of a hepatocellular origin. Like in human HCC, all K19 positive hepatocellular neoplasias were glypican-3 positive and histologically poorly differentiated and revealed intra- or extrahepatic metastases whereas K19 negative hepatocellular neoplasias did not.

Conclusions

K19 positive hepatocellular neoplasias are highly comparable to man and occur in 12% of canine hepatocellular tumours and are associated with a poorly differentiated histology and aggressive tumour behaviour.