Arterial elements and perisinusoidal cells in borderline hepatocellular nodules and small hepatocellular carcinomas

Expression of CD34 in cirrhotic liver--reliance to dedifferentiation

BACKGROUND/AIM

The vascular supply of dysplastic nodules (DN) is altered compared with surrounding cirrhotic nodules. Dysplastic nodules contain unpaired arteries which are isolated arteries unaccompained by bille ducts. In adition, capillarization or neovascularization is evident on CD34 and CD31 staining. The investigation of angiogenic profile of regenerative, dysplastic and nodules of hepatocellular carcinoma aimed at assessing whether vascular profile is in reliance to the process of dedifferentiation of hepatocytes during the course of cirrhosis.

METHODS

Thirty four liver nodules from surgical biopsies of 12 patients previously undiagnosed to have cirrhosis, were classified as regenerative, dysplastic and small hepatocellular carcinomas (HCC). The investigation included 8 large regenerative nodules (LRN), 11 low grade dysplastic nodules (LGDN), 12 high grade dysplastic nodules (HGDN) and 3 early HCC. Serial sections of the nodules and surrounding cirrhotic liver tissue were immunostained against CD34. The vascular counting method was performed. The results were analysed using SPSS computer statistical program.

RESULTS

The number of capillary unites showed significant differences among nodular types, with the largest number of capillaries in hepatocellular carcinoma as well as strong reliance to dedifferentiation.

CONCLUSION

There is a significant correlation of sinusoidal capillarization to dediferentiation of the liver tissue during the course of cirrhosis. From diagnostic view, capillary counting may be helpful to distinguish dysplastic from nondysplastic nodules. The appearance of dysplastic nodules in nonselected surgical biopsies is frequent enough to challenge caution during the follow-up of cirrhotic patients.

Vascular endothelial growth factor receptor 2 expression in non-tumorous cirrhotic liver is higher when hepatoma is beyond Milan criteria

Hepatocellular carcinoma (HCC) is a highly vascular tumor. Angiogenesis in HCC is mediated at least in part by vascular endothelial growth factor (VEGF), which is expressed in HCC and surrounding cirrhotic tissue. VEGF mediates its angiogenic effects through multiple receptors including VEGF receptor 2 (VEGFr2, KDR/FLK-1), The distribution and clinical significance of VEGFr2 expression in HCC and cirrhotic liver in the setting of liver transplantation have not been tissue site specific evaluated. Immunohistochemical staining for VEGFr2 was performed in 78 liver explants from patients with HCC undergoing liver transplantation. VEGFr2 levels in HCC were significantly increased compared to adjacent, nontumorous cirrhotic liver areas (P < 0.05). VEGFr2 levels were significantly higher in the veins and sinusoids of poorly differentiated tumors (P < 0.05). VEGFr2 levels in the tumors were not significantly different between patients within and beyond Milan criteria. However, VEGFr2 levels were significantly higher in the arteries of non-tumorous liver in patients beyond Milan criteria (P < 0.05). No significant association was observed between VEGFr2 levels and the presence of tumor vascular invasion or recurrence post transplantation. These findings suggest that VEGFr2 up-regulation is a feature of poor differentiation and tumor progression. Further investigation is needed to assess the value of angiogenesis modulation in preventing tumor formation and/or progression in cirrhotic patients.

Analysis of morphological variables and arterialization in the differential diagnosis of hepatic nodules in explanted cirrhotic livers

Background

Many terminologies have been given to dysplastic hepatocellular nodules, which are preneoplastic lesions. In 1995, the International Working Party meeting established the nomenclature and morphological criteria for hepatocellular nodular lesions. Nevertheless, an unequivocal differential diagnosis is sometimes difficult, particularly among large regenerative nodules, dysplastic nodules and hepatocellular carcinoma. Angiogenesis is observed during hepatocarcinogenesis and the presence of the isolated arteries may help to discriminate these nodules. The relevance of the International Working Party histological variables and presence of the isolated arteries were analyzed with regard to the diagnosis of large regenerative nodules, low and high grade dysplastic nodules and hepatocellular carcinoma, in order to evaluate which have a real contribution in such diagnoses.

Methods

One hundred and seven nodular hepatocellular lesions over 5 mm (or smaller nodules with a different color) from explanted cirrhotic livers were analyzed and classified following the criteria of the International Working Party. Classifications were as follows: large regenerative nodules, low grade dysplastic nodules, high grade dysplastic nodules and hepatocellular carcinoma. The presence of isolated arteries (not related to the portal tracts or fibrosis) was verified for the nodules.

Results

Among the 107 nodular lesions studied, 17 were classified as large regenerative nodules, 38 as low grade dysplastic nodules, 28 as high grade dysplastic nodules and 24 as hepatocellular carcinoma. The most relevant International Working Party variables in the differential diagnosis of the nodules were cellularity, trabeculae thickness, cytoplasmic staining, nuclear atypia, pseudoacinar pattern, portal tracts, nucleocytoplasmic ratio and mitosis. The isolated arteries, identified by hematoxylin and eosin staining, were important discriminating between two groups: low grade lesions (large regenerative nodules/low grade dysplastic nodules) and high grade lesions (high grade dysplastic nodules/hepatocellular carcinoma) (P < 0.001).

Conclusion

The International Working Party criteria allow for the classification of the majority of hepatocellular nodules. However, other features such as cytoplasmatic tintorial affinity and pseudoacinar pattern may contribute to these diagnoses. The finding of isolated arteries in a nodular lesion should be investigated carefully, since the nodule could be a dysplastic lesion or hepatocellular carcinoma.

From molecular biology to targeted therapies for hepatocellular carcinoma: the future is now

Hepatocellular carcinoma (HCC) is characterized as a highly chemoresistant cancer with no effective systemic therapy. Despite surgical or locoregional therapies, prognosis remains poor because of high tumor recurrence or tumor progression, and currently there are no well-established effective adjuvant therapies. The molecular biology of carcinogenesis and tumor progression of HCC has been increasingly understood with intense research in recent years. Several important intracellular signaling pathways such as the Ras/Raf/Mek/Erk pathway and PI3k/Akt/mTOR pathway have been recognized, and the role of several growth factors and angiogenic factors such as EGF and VEGF has been confirmed. Effective agents targeting these molecular abnormalities have been developed and widely tested in preclinical studies of HCC cell lines or xenograft models. Several agents have entered clinical trials in HCC patients, and recent data indicated that a multikinase inhibitor targeting Ras kinase and VEGFR-2, sorafenib, is effective in prolonging survival of patients with advanced HCC. The management of advanced HCC is entering the era of molecular targeting therapy, which is of particular significance for HCC in view of the lack of existing effective systemic therapy for this cancer.

Hepatic precancerous lesions and small hepatocellular carcinoma

Precancerous lesions that may be detected in chronically diseased, usually cirrhotic livers, include: clusters of hepatocytes with atypia and increased proliferative rate (dysplastic foci) that usually represent an incidental finding in biopsy or resection specimens; and grossly evident lesions (dysplastic nodules) that may be detected on radiologic examination. There are two types of small hepatocellular carcinoma (HCC) (defined as HCC that measures less than 2 cm): early HCC, which is well-differentiated and has indistinct margins; and distinctly nodular small HCC, which is well- or moderately differentiated, and is usually surrounded by a fibrous capsule. Precise diagnosis of precancerous and early cancerous lesions by imaging methods is often difficult or impossible. Detection of a dysplastic lesion in a biopsy specimen is a marker of increased risk for HCC development, and warrants increased surveillance. High-grade dysplastic nodules and small HCCs should be treated by local ablation, surgical resection, or liver transplantation.

Clinicopathological features of hepatocellular carcinoma evaluated by vascular endothelial growth factor expression

AIM

To evaluate the significance of the expression of vascular endothelial growth factor (VEGF), its correlation with clinicopathological variables were studied in the tissue of hepatocellular carcinoma (HCC) and surrounding liver.

METHODS

In 56 samples (tumor and non-tumor liver tissue) collected from 28 patients, VEGF expression was examined by immunohistochemistry and western blot analysis.

RESULTS

The value of VEGF expression by western blotting was correlated with immunohistochemical staining grade. In tumor tissue, the value of VEGF expression correlated with tumor size (P = 0.034), á-fetoprotein (P = 0.036) and protein induced by vitamin K absence-II by simple regression, and histological grade (P = 0.0132) by the unpaired t-test. The level of VEGF expression in non-tumor liver was found to correlate with the value of serum albumin (P = 0.008), cholinesterase (P = 0.012) and prothrombin activity (P = 0.046). The frequency of simple nodular type in gross appearance decreased in cases with high tumor/non-tumor (T/N) ratio (P = 0.022), and the degree of portal vein invasion progressed with an increase in the T/N ratio (P = 0.008). The T/N ratio was significantly higher in early recurrence cases (P = 0.0081).

CONCLUSION

This study on the expression of VEGF might be useful to estimate the liver condition and the clinicopathological features of HCC.

Enhancement patterns and signal-intensity characteristics of small hepatocellular carcinoma in cirrhosis: pathologic basis and diagnostic challenges

Recent pathologic studies of hepatic resection and transplantation specimens have elucidated the morphologic features of the precancerous lesions and small hepatocellular carcinomas (HCCs) arising in cirrhotic livers. Small HCCs measuring less than 2 cm in diameter are of two types: vaguely nodular, well-differentiated tumors, also known as "early" HCCs, and distinctly nodular tumors, with histologic features of "classic" HCC. The precancerous lesions include dysplastic foci and dysplastic nodules. "Classic" small HCCs are supplied by nontriadal arteries, whereas early HCCs and dysplastic nodules may receive blood supply from both portal tracts and nontriadal arteries. The similarities in blood supply of these three types of nodular lesions result in significant overlap of findings on dynamic imaging. Nevertheless, small HCCs sometimes display characteristic radiologic features, such as "nodule-in-nodule" configuration and "corona enhancement" pattern. Moreover, various histologic features of these nodular lesions may also be related to a variety of signal intensities and attenuation coefficients, while the presence of cirrhosis is known to limit the sensitivity and specificity of any imaging modality, due to liver inhomogeneity. Because of these reasons, imaging findings of nodular lesions in cirrhotic livers are often inconclusive, emphasizing the need for a better understanding of these imaging features.

Des-gamma-carboxyl prothrombin-promoted vascular endothelial cell proliferation and migration

Des-gamma-carboxyl prothrombin (DCP) is a well recognized tumor marker for hepatocellular carcinoma. Previously, we have demonstrated that DCP stimulates cell proliferation in hepatocellular carcinoma cell lines through Met-Janus kinase 1 signal transducer and activator of transcription 3 signaling pathway. In the present study, we demonstrated that DCP induces both cell proliferation and migration in human umbilical vein endothelial cells. DCP was found to bind with the kinase insert domain receptor (KDR), alternatively referred to as vascular endothelial growth factor receptor-2. Furthermore, DCP induced autophosphorylation of KDR and its downstream effector phospholipase C-gamma and mitogen-activated protein kinase (MAPK). To support these results, we showed that DCP-induced cell proliferation and cell migration were inhibited by KDR short interfering RNA, KDR kinase inhibitor, or MAPK inhibitor. In conclusion, these results indicate that DCP is a novel type of vascular endothelial growth factor that possesses potent mitogenic and migrative activities.

Angiogenesis and antiangiogenic therapy in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a hypervascular tumor characterized by neovascularization, which plays an important role in the growth and progression of HCC. Angiogenesis provides a target for novel prognostic and therapeutic approaches to HCC. Assessment of microvessel density using immunohistochemical staining for specific endothelial cell markers such as CD34 has been shown to provide prognostic information independent of conventional pathological parameters in HCC patients. Recent studies have unveiled the important angiogenic factors involved in the regulation of angiogenesis in HCC, although the exact molecular pathways are far from clear. Current data suggest that vascular endothelial growth factor (VEGF) plays a critical role in angiogenesis of HCC. Tumor expression of VEGF has been shown to correlate with tumor invasiveness and prognosis in patients with HCC. VEGF is an important molecular target for antiangiogenic therapy. Studies in animal models have demonstrated the efficacy of antiangiogenic agents such as anti-VEGF antibody and antagonists of VEGF receptors in suppressing hepatocarcinogenesis and growth of HCC. Antiangiogenic therapy has already entered clinical trials in HCC patients and holds the promise of providing an effective novel treatment for HCC, which is of great clinical significance because there is no existing effective systemic therapy for HCC.

Origin of neovascular structure in an early stage of hepatocellular carcinoma: study of alpha-smooth muscle actin immunohistochemistry in serial thin sections of surgically resected cancer

BACKGROUND

To elucidate the origin of the neovascular structure found in well-differentiated hepatocellular carcinoma (HCC), an immunohistochemical study was performed on sequential thin section specimens.

METHOD

Eleven surgically resected specimens of well-differentiated HCC were analyzed for neovascular structure using monoclonal alpha-smooth muscle actin (alpha-SMA) antibody. Each paraffin specimen was serially sliced to a thickness of 3 microm for immunohistochemistry. When a ring-shaped structure was found unrelated to portal triads on alpha-SMA staining, it was regarded as abnormal neovascularity (non-triadal vessel or unaccompanied vessel).

RESULTS

All of the 11 liver cancers had thin-walled, round- or oval-shaped non-triadal vessels in their well-differentiated parts. Immunohistochemistry of serial thin sections of HCC showed that these non-triadal vessels were connected to portal veins in portal triads in well-differentiated cancer in a total of nine patients (81.8%). This type of neovascular structure found in a well-differentiated cancer seemed to be a surviving portal vein among diminishing and disappearing arteries and bile ducts. All 11 tumors showed isovascular staining on ordinary digital subtraction angiography, and four of the tumors showed negative enhancement on intra-arterial carbon dioxide-enhanced ultrasonography or computerized tomographic (CT) hepatic arteriography, suggesting a relative arterial blood scarcity in the tumor nodules.

CONCLUSION

At an early stage of HCC, non-triadal vessels originate from ordinary portal veins in intratumoral portal triads. This fact sufficiently explains the reason why a well-differentiated liver cancer can sometimes show arterial blood paucity on CT arteriography or enhanced ultrasonography.

Characterization of small nodules in cirrhosis by assessment of vascularity: the problem of hypovascular hepatocellular carcinoma

In a prospective study, we examined the impact of arterial hypervascularity, as established by the European Association for the Study of the Liver (EASL) recommendations, as a criterion for characterizing small (1-3 cm) nodules in cirrhosis. A total of 72 nodules (1-2 cm, n = 41; 2.1-3 cm, n = 31) detected by ultrasonography in 59 patients with cirrhosis were included in the study. When coincidental arterial hypervascularity was detected at contrast perfusional ultrasonography and helical computed tomography, the lesion was considered to be hepatocellular carcinoma (HCC) according to EASL criteria. When one or both techniques showed negative results, ultrasound-guided biopsy was performed. In cases with negative results for malignancy or high-grade dysplasia, biopsy was repeated when an increase in size was detected at the 3-month follow-up examination. Coincidental hypervascularity was found in 44 of 72 nodules (61%; 44% of 1-2-cm nodules and 84% of 2-3-cm nodules). Fourteen nodules (19.4%) had negative results with both techniques (hypovascular nodules). Biopsy showed HCC in 5 hypovascular nodules and in 11 of 14 nodules with hypervascularity using only one technique. All nodules larger than 2 cm finally resulted to be HCC. Not satisfying the EASL imaging criteria for diagnosis were 38% of HCCs 1 to 2 cm (17% hypovascular) and 16% of those 2 to 3 cm (none hypovascular). In conclusion, the noninvasive EASL criteria for diagnosis of HCC are satisfied in only 61% of small nodules in cirrhosis; thus, biopsy frequently is required in this setting. Relying on imaging techniques in nodules of 1 to 2 cm would miss the diagnosis of HCC in up to 38% of cases. Any nodule larger than 2 cm should be regarded as highly suspicious for HCC.

Are gap junction gene connexins 26, 32 and 43 of prognostic values in hepatocellular carcinoma? A prospective study

AIM

To investigate the prognostic value of the expression of connexin (Cx) 26, 32 and 43 messenger RNA (mRNA) in hepatocellular carcinoma (HCC) tissues.

METHODS

Using a reverse-transcriptase polymerase chain reaction (RT-PCR), Cx 26, Cx 32 and Cx 43 mRNAs were determined in the liver tissues of 15 controls and in HCC tissues of 25 patients undergoing curative hepatic resection. The patients were followed up clinically.

RESULTS

Cx 26 and Cx 32 mRNAs were significantly lower in HCC tissues compared with controls (both P<0.01). By multivariate analysis, a lower level of Cx 26 and Cx 32 mRNA correlated significantly with a risk of HCC recurrence (P = 0.033) and recurrence-related mortality (P = 0.031, P = 0.031). Cx 43 mRNA was higher in HCC tissues compared with controls but did not correlate with postoperative recurrence or recurrence-related mortality. Other significant predictors of HCC recurrence included cellular dedifferentiation (P = 0.033), less encapsulation (P = 0.050), vascular permeation (P = 0.046), and daughter nodules (P = 0.046). Significant variables related to recurrence-related mortality consisted of cell dedifferentiation (P = 0.031), vascular permeation (P = 0.048), and daughter nodules (P = 0.048). The levels of Cx 26 and Cx 32 mRNAs correlated significantly with cell differentiation (P = 0.031).

CONCLUSION

A low expression of Cx 26 and Cx 32 mRNAs in HCC tissues is predictive of postoperative recurrence of HCCs.

Immunohistochemical and molecular markers in the diagnosis of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has distinct morphologic features and can be identified in the majority of cases by routine hematoxylin and eosin (H&E)-stained formalin-fixed paraffin-embedded sections. However, distinguishing a well-differentiated HCC from normal or regenerative tissue may be very difficult in some cases, particularly in small needle aspiration or core biopsies. Furthermore, some of the unusual morphologic variants, including clear-cell, pleomorphic, and sarcomatoid variants, may be mistaken for metastases. Similarly, metastases from various primary tumors to the liver may be mistaken for primary hepatic tumors. In this overview, we summarize the immunohistochemical and molecular markers that have been developed to address these diagnostic challenges. Among the numerous diagnostic markers studied, pCEA, HepPar 1, CD34, CK 7, CK 19, CK 20, and albumin in situ (ISH) have been found to be valuable in distinguishing HCC from metastatic neoplasms of extrahepatic sites.

Angiogenesis in hepatocellular carcinoma: the retrospectives and perspectives

Hepatocellular carcinoma (HCC) is a typical hypervascular tumor. Many angiogenic factors have been studied in HCC, and several anti-angiogenic therapies have been tested in animal models and patients. This paper summarizes the latest findings, especially regarding the clinical significance of endothelial cell markers and angiogenic factors in HCC, and experimental and clinical anti-angiogenesis therapies. Further developments in this area, such as endothelial cell-oriented research and better experimental and clinical designs in the evaluation of anti-angiogenic therapies are discussed.

Prognostic significance of preoperative circulating vascular endothelial growth factor messenger RNA expression in resectable hepatocellular carcinoma: A prospective study

AIM: To investigate the prognostic value of vascular endothelial growth factor messenger RNA (VEGF mRNA) in the peripheral blood (PB) of patients with hepatocellular carcinoma (HCC) undergoing curative resection.

METHODS: Using a reverse-transcription polymerase chain reaction (RT-PCR)-based assay, VEGF mRNA in the PB was determined prospectively in 50 controls and in 50 consecutive patients undergoing curative resection for HCC.

RESULTS: Among the isoforms of VEGF mRNA, VEGF₁₆₅ and VEGF₁₂₁ were expressed. By multivariate analysis, a higher level of VEGF₁₆₅ in preoperative PB correlated with a risk of HCC recurrence with borderline significance (P = 0.050) and significantly with recurrence-related mortality (P = 0.048); while VEGF₁₂₁ did not. Other significant predictors of HCC recurrence included cellular dedifferentiation (P = 0.033), an absent or incomplete capsule (P = 0.020), vascular permeation (P = 0.018), and daughter nodules (P = 0.006). The other significant parameter of recurrence related mortality was cellular dedifferentiation (P = 0.053). The level of circulating VEGF mRNA, however, did not significantly correlate with tumor size, cellular differentiation, capsule, daughter nodules, vascular permeation, necrosis and hemorrhage of tumors.

CONCLUSION: The preoperative level of circulating VEGF mRNA, especially isoform VEGF₁₆₅, plays a significant role in the prediction of postoperative recurrence of HCC.

Is the vascular endothelial growth factor messenger RNA expression in resectable hepatocellular carcinoma of prognostic value after resection ?

AIM: To study whether vascular endothelial growth factor messenger RNA (VEGF mRNA) in the hepatocellular carcinoma (HCC) tissues obtained after curative resection has a prognostic value.

METHODS: Using a reverse-transcription polymerase chain reaction (RT-PCR)-based assay, VEGF mRNA was determined prospectively in liver tissues of 50 controls and in HCC tissues of 50 consecutive patients undergoing curative resection for HCC.

RESULTS: Among the isoforms of VEGF mRNA, VEGF₁₆₅ and VEGF₁₂₁ were expressed. By multivariate analysis, a higher level of VEGF₁₆₅ in HCC tissue correlated with a significant risk of HCC recurrence (P = 0.038) and significantly with recurrence-related mortality (P = 0.045); while VEGF₁₂₁ did not. Other significant predictors of HCC recurrence included cellular dedifferentiation (P = 0.033), an absent or incomplete capsule (P = 0.020), vascular permeation (P = 0.018), and daughter nodules (P = 0.006). The other significant variables of recurrence related mortality consisted of vascular permeation (P = 0.045), and cellular dedifferentiation (P = 0.053). The level of VEGF mRNA in HCC tissues, however, did not significantly correlate with tumor size, cellular differentiation, capsule, daughter nodules, vascular permeation, necrosis and hemorrhage of tumors.

CONCLUSION: The expression of VEGF mRNA, especially isoform VEGF₁₆₅, in HCC tissues, may play a significant and independant role in the prediction of postoperative recurrence of HCC.

Caveolin and Thrombospondin Expression During Hepatocellular Carcinogenesis

Macroregenerative and dysplastic nodules (MDNs) are hepatocellular carcinoma (HCC) precursor lesions and exhibit distinct vascular profiles relative to adjacent cirrhotic liver. Recent microarray analysis of MDN identified aberrant expression of caveolin-1 and thrombospondin-1, genes suspected to play a role in tumorigenesis at other sites. We used immunohistochemistry to localize caveolin and thrombospondin expression in 14 MDNs from livers with hepatitis C cirrhosis and in tissue arrays that included samples of MDNs, HCC, and nonneoplastic liver. Hepatocytes were uniformly negative for caveolin. Sinusoidal endothelial cells exhibited increased caveolin expression in MDNs relative to adjacent cirrhotic liver in most (28 of 36, 78%) MDNs evaluated. However, few HCCs showed increased caveolin expression as compared with nonneoplastic liver (5 of 19, 26%). Unpaired arteries showed strong positive endothelial cell staining. Thrombospondin staining was weak or negative in hepatocytes in nearly all (77 of 92, 84%) MDNs and in 46 of 49 HCCs evaluated (94%). Sinusoidal endothelial cells were negative for thrombos pondin, but hepatic arteries and MDNs showed positive mural staining; portal veins were positive both in vessel walls and in endothelial cells. The altered expression profiles of these genes identified in microarray analysis are not likely related directly to malignant transformation of hepatocytes but rather to an alteration in the vascular supply to these lesions. The results illustrate the critical role of histologic techniques in interpretation of microarray data.

Chromosomal alterations in hepatocellular nodules by comparative genomic hybridization: high-grade dysplastic nodules represent early stages of hepatocellular carcinoma

Data from experimental hepatocarcinogenesis and recent studies in humans have suggested that the emergence of hepatocellular carcinoma (HCC) is a stepwise process. However, despite abundant experimental data, the precise molecular mechanisms and genetic alterations involved in human liver carcinogenesis are still unclear. Comparative genomic hybridization was used to analyze 26 hepatocellular nodules obtained from patients undergoing liver transplantation or surgical resection for HCC. According to the criteria proposed by the International Working Party, 16 nodules were classified as multiacinar regenerative nodules (MRN), 4 as low-grade dysplastic nodules (LG-DN), and 6 as high-grade dysplastic nodules (HG-DN). Our aim was to investigate the possible genetic differences between MRN, LG-DN, and HG-DN. The whole group of nodules showed only a few aberrations (mean 1.1/case), without any significant pattern. This finding is comparable to what happens in non-neoplastic tissue. On the contrary, in three of six HG-DN, we found deletions of 8p and gains of 1q. LG-DN and MRN did not show these chromosomal imbalances. These results confirm the important role of allelic losses on 8p as well as of gains of 1q in HCC. We conclude that the genes that are important in early stages of hepatocarcinogenesis are probably located on these chromosomal arms.

The role of immunohistochemistry in diagnosis

Immunohistochemistry is a strong tool in hepatopathologic diagnosis: the technique is relatively simple and inexpensive. New and very sensitive detection methods have been recently developed (e.g., the EnVision technique and the microwave antigen retrieval method). This article discusses the role of immunohistochemistry in differentiating chronic cholestatic diseases from chronic hepatitis and in characterizing infectious agents. Algorythms for the typing of lymphomas and for the differentiation of primary tumors versus metastases are proposed as well. The immunohistochemical criteria for the diagnosis of premalignant lesions are discussed.

Tumor microvessel density as a predictor of recurrence after resection of hepatocellular carcinoma: a prospective study

PURPOSE

This study prospectively evaluated the correlation of tumor microvessel density (MVD) with clinicopathologic features and postoperative recurrence in patients undergoing resection of hepatocellular carcinoma (HCC).

PATIENTS AND METHODS

Tumor MVD was assessed in 100 patients with resection of HCC using a computer image analyzer after immunostaining for CD34 (MVD-CD34) and von Willebrand factor (MVD-vWF), respectively. Patients were prospectively followed for recurrence.

RESULTS

Mean tumor MVD-CD34 (236/0.74 mm(2)) was higher than mean tumor MVD-vWF (87/0.74 mm(2)) (P <.001). By multiple regression analysis, tumor size was the only pathologic feature significantly related to tumor MVD-CD34. The median MVD-CD34 was 316/0.74 mm(2) in HCCs < or = 5 cm (n = 46) and 146/0.74 mm(2) in HCCs more than 5 cm (n = 54) (P <.001). Among patients with HCCs < or = 5 cm, those with higher than median MVD-CD34 had worse disease-free survival (at 3 years, 13%) than those with a lower MVD-CD34 (at 3 year, 74%) (P =.002). Multivariate analysis showed that tumor MVD-CD34 was the only significant factor predictive of disease-free survival in patients with HCC < or = 5 cm. For HCCs more than 5 cm, MVD-CD34 did not have a significant prognostic influence. MVD-vWF did not have a significant prognostic influence on disease-free survival in either HCCs < or = 5 cm or more than 5 cm.

CONCLUSION

This study shows that a high MVD-CD34 was predictive of early postresection recurrence in patients with HCCs < or = 5 cm and, therefore, may be a novel prognostic marker in this subset of patients.

Expression of smooth muscle calponin in tumor vessels of human hepatocellular carcinoma and its possible association with prognosis

BACKGROUND

Hepatocellular carcinoma (HCC) is a vascular-rich tumor. The tumor vessels in HCC were demonstrated to have alpha-smooth muscle actin positive smooth muscle cells (SMCs). However, it is unclear whether the SMCs in the wall of the tumor vessels are differentiated or undifferentiated. Basic calponin is an actin-, tropomyosin-, and calmodulin-binding protein, and expression of the calponin gene in SMCs has been recognized as one of the late stage differentiation markers of SMCs. The authors investigated the differentiation state of SMCs in tumor vessels by immunohistochemical examination of calponin in patients with HCC, and whether it is associated with the patients' prognosis.

METHODS

Tumor and nontumor tissues were obtained from 75 patients with HCC who underwent radical hepatic resection. The differentiation state of the smooth muscle cells were evaluated based on the expression level of calponin, an actin-binding protein, using immunohistochemistry and reverse transcription-polymerase chain reaction analysis. The disease free survival (DFS) rates were estimated according to the Kaplan-Meier method comparing groups of patients with calponin positive and negative tumor vessels. A multivariate analysis based on the Cox proportional hazards regression model was performed to estimate whether the expression of calponin is an independent prognostic factor.

RESULTS

In the 75 patients with HCC examined, 36 patients (48%) possessed calponin positive SMCs, and the remaining 39 (52%) did not. There were no significant differences in either clinical or pathologic factors between the two groups of patients. The 5- and 8-year DFS rate of the patients with calponin positive vessels were 37% and 26%, respectively. These values were significantly higher (11% and 5%) than those of patients with calponin negative vessels. Gender, TNM classification, perioperative transfusion, and calponin expression were found to be independent prognostic factors for DFS.

CONCLUSIONS

Immunohistochemical examination of the calponin expression in the tumor vessels is a new and useful means to predict the prognosis of HCC patients after hepatic resection.

Increased mast cells in hepatocellular carcinoma and intrahepatic cholangiocarcinoma

BACKGROUND/AIMS

Human mast cells are categorized into those positive only for tryptase (MC(T)) and those positive for both tryptase and chymase (MC(TC)).

METHODS

We investigated mast cells in "normal" livers (n=13), hepatocellular carcinoma (HCC) (n= 49) and intrahepatic cholangiocarcinoma (ICC) (n= 44) by double immunostaining and quantitative morphometry.

RESULTS

In "normal" livers, mast cells were located in portal tracts, and to a lesser extent in the sinusoids. In HCC, mast cells were noted in tumoral sinusoids and fibrous septa. In ICC, many mast cells were present in tumoral stroma. Morphometry showed that densities of mast cells in HCC and ICC were significantly higher than those in "normal" livers. The density of mast cells in ICC (57.6+/-62.4/mm2) was significantly higher than that in HCC (9.32+/-12.9/mm2). The density of sinusoidal mast cells was significantly higher in HCC (1.79+/-2.35/mm2) than in "normal" livers (0.13+/-0.07/mm2). The density of stromal mast cells was significantly higher in ICC (57.6+/-62.4/mm2) than that of portal tracts in "normal" livers (28.4+/-7.0/mm2). MC(T) and MC(TC) were approximately 20% and 80%, respectively, being consistent in any anatomical compartments.

CONCLUSIONS

Mast cells increase during carcinogenesis in HCC and ICC, and they may play a role in fibrosis or tumor immunology in HCC and ICC.

The significance of thymidine phosphorylase activity in hepatocellular carcinoma and chronic diseased livers: a special reference to liver fibrosis and multicentric tumor occurrence

The role of thymidine phosphorylase (TP), an angiogenic factor, in hepatocellular carcinoma (HCC) remains unclear. The aim of this study was to clarify the significance of TP in HCC. Thirty-seven patients with HCC, who underwent hepatectomy, were included. The TP activity in both cancerous and non-cancerous parts of livers were measured by an enzyme-linked immunosorbent assay. Another 11 patients without HCC were used to evaluate the TP activity in the non-cancerous parts of livers. Both the cancerous and non-cancerous TP activities were clinico-pathologically investigated with special reference to the multicentric occurrence of HCCs and the degree of liver fibrosis; consisting of normal, fibrosis and cirrhosis. The TP activity in the cancerous part was 94.6 +/- 70.2 U/mg protein, while that in non-cancerous parts of the liver was 80.9 +/- 48.8 U/mg protein. No significant difference was observed. The TP activity in the cancerous part did not correlate with any clinicopathological variables, such as tumor differentiation, portal vein invasion, intrahepatic metastases and prognosis. However, the TP activity in the non-cancerous parts of the liver correlated with the degree of fibrosis (normal/fibrosis/cirrhosis = 34:74:90 U/ mg protein, respectively). Furthermore, regarding the correlation between TP activity in the non-cancerous parts and the simultaneously multicentric occurrence of HCC, the TP activity in the multicentric group (n = 8; 121 U/mg protein) was significantly higher than that in the non-multicentric group (n = 29; 70 U/mg protein). The TP activity in the non-cancerous parts increased in proportion to the degree of liver fibrosis. Furthermore, it is suggested that the higher TP activity in the non-cancerous part is related to the multicentric occurrence of HCCs.

Protein expression of CD44 (standard and variant isoforms) in hepatocellular carcinoma: relationships with tumor grade, clinicopathologic parameters, p53 expression, and patient survival

BACKGROUND/AIMS

Members of the CD44 family are transmembrane glycoproteins which act mainly as receptors for hyaluronan. We have examined the expression of CD44s and several CD44v and the relationship between these and hepatocellular carcinoma (HCC) grade, clinicopathological parameters, p53 expression, and patient survival in HCC.

METHODS

Formalin-fixed, paraffin-embedded tissue sections from 107 surgically resected HCC were examined immunohistochemically using a semi-quantitative scoring system to detect the expression of different forms of CD44.

RESULTS

The number of CD44s-positive cases was 36 (34%), CD44v5 52 (49%), CD44v6 29 (27%), CD44v7-8 41 (38%), and CD44v10 26 (24%). Expression of these molecules correlated with high histological grade, being the highest in poorly-differentiated HCC. High CD44v6 expression significantly correlated with the presence of vascular invasion and p53 overexpression. Kaplan-Meier examination of patient survival revealed that HCC patients with positivity of each of these five molecules had a reduced survival rate, and that HCC patients positive for all the five CD44 molecules had worse survival than HCC patients positive for four or less of these CD44 molecules. In multivariate survival analysis, CD44s positivity was an independent factor. However, positivity for one or more CD44 isoforms was the most useful independent factor for overall survival.

CONCLUSION

These results suggest that up-regulation of CD44 isoforms is associated with poorly-differentiated HCC and shortened survival.

Implications of human macrophage metalloelastase and vascular endothelial growth factor gene expression in angiogenesis of hepatocellular carcinoma

OBJECTIVE

To determine molecular mechanisms involved in angiogenesis of hepatocellular carcinoma (HCC).

SUMMARY BACKGROUND DATA

Tumor angiogenesis is believed to derive from the balance between angiogenic stimulators and inhibitors. It has been suggested that the switch to the angiogenic phenotype requires both upregulation of the first and downregulation of the second. However, its molecular basis in vivo remains obscure. In this study the authors analyze the participation of two factors in angiogenesis of HCC- human macrophage metalloelastase (HME), a matrix metalloproteinase responsible for the generation of angiostatin, a potent angiogenesis inhibitor, and vascular endothelial growth factor (VEGF), the most potent endogenous angiogenic factor.

METHODS

Tumorous and contiguous nontumorous tissues from 25 patients with HCC who underwent curative partial hepatectomy were subjected to Northern blot analysis to detect HME and VEGF messenger RNA (mRNA) expression. Western blot analysis was used to detected angiostatin. Tumor vascularity was evaluated using hepatic angiography.

RESULTS

Eleven of the 15 cases expressing the HME gene showed hypovascular tumors, whereas hypervascular tumors were seen in 9 of the 10 HME-negative cases. The median of HME mRNA expression (tumorous/nontumorous ratio) was 6.5 (range 0-264.5) in the hypovascular group and 0 (range 0-3.2) in the hypervascular group. A stepwise logistic analysis revealed that HME and VEGF mRNA expression were two independent variables significantly affecting the vascularity of HCC tumors.

CONCLUSION

HME gene expression is significantly associated with hypovascular tumors; moreover, angiogenesis in HCC is not determined by a single factor, but depends on the net balance between HME and VEGF gene expressions.

The vascular profile of regenerative and dysplastic nodules of the cirrhotic liver: implications for diagnosis and classification

We investigated the angiogenic phenotype of regenerative and dysplastic hepatocellular nodules to assess whether these lesions have distinct vascular profiles compared with the adjacent nonneoplastic or malignant liver. Forty-three liver nodules surgically removed from 18 patients were classified into regenerative and dysplastic categories. Serial sections of each nodule, adjacent cirrhotic liver (16 patients), and associated hepatocellular carcinoma (HCC) (6 patients), have been immunostained against CD31 and alpha-smooth muscle actin (alphaSMA) to detect capillary and muscular vessels. The study included 20 large regenerative nodules (LRNs), 13 low-grade dysplastic nodules (LGDNs), and 10 high-grade dysplastic nodules (HGDNs). The number of both capillary units and unpaired arteries was significantly increased in HGDNs and malignant lesions over LGDNs, regenerative, and cirrhotic nodules (P <.01), which showed an overlapping vascular profile. In addition, the number of capillary units, but not that of unpaired arteries, was significantly increased in HCC compared with HGDNs (P <.01). These results show that certain angiogenic features segregate HGDNs from other nonmalignant nodules such as LRNs and LGDNs. The former group of lesions is similar to HCC whereas the latter group is undistinguishable from the adjacent cirrhosis as far as their vascular profile is concerned. The adopted investigative approach does not support the morphological distinction between LRNs and LGDNs although it suggests that HGDNs are likely advanced precursors of HCC. An abnormal number of capillary units and/or unpaired arteries in a nonmalignant hepatocellular nodule can be diagnostically helpful to identify a precancerous lesion.

Myofibroblasts and hepatocellular carcinoma: an in vivo and in vitro study

BACKGROUND/AIMS

The number of perisinusoidal myofibroblasts has been shown to be increased in hepatocellular carcinoma, as compared to cirrhosis. This increase might suggest a cooperative relationship between tumour cells and myofibroblasts. To assess this relationship, we undertook: (a) an immunohistochemical study to confirm the existence of an increased number of perisinusoidal myofibroblasts in human hepatocellular carcinoma, as compared to cirrhosis with or without liver cell dysplasia, (b) an in vitro study testing the role of normal or tumoral human hepatocytes in myofibroblast proliferation.

METHODS

Forty explanted cirrhotic livers, including 14 with hepatocellular carcinoma and 24 with liver cell dysplasia, were studied. Myofibroblasts were detected by immunohistochemistry using an antibody directed against alpha-smooth muscle actin. Hepatic myofibroblasts in culture were obtained by outgrowth from human liver explants.

RESULTS

There was a progressive increase in the number of perisinusoidal myofibroblasts, from cirrhotic nodules without dysplasia to liver cell dysplasia and hepatocellular carcinoma. Conditioned medium from isolated normal human hepatocytes had only minor mitogenic effects on myofibroblasts, as assessed by measuring DNA synthesis and cell growth. In contrast, conditioned medium from a human hepatoma cell line (HepG2 cells) markedly stimulated the proliferation of human myofibroblasts. This mitogenic activity was stored in HepG2 cells and secreted in the extracellular medium rather than being simply released following cell lysis.

CONCLUSIONS

These results suggest that the increased number of myofibroblasts in hepatocellular carcinoma might be due to a paracrine mechanism involving soluble mitogenic factor(s) secreted by tumour cells.