Swan N. Thung

HGF, SDF-1, and MMP-9 are involved in stress-induced human CD34 + stem cell recruitment to the liver

Hematopoietic stem cells rarely contribute to hepatic regeneration, however, the mechanisms governing their homing to the liver, which is a crucial first step, are poorly understood. The chemokine stromal cell-derived factor-1 (SDF-1), which attracts human and murine progenitors, is expressed by liver bile duct epithelium. Neutralization of the SDF-1 receptor CXCR4 abolished homing and engraftment of the murine liver by human CD34+ hematopoietic progenitors, while local injection of human SDF-1 increased their homing. Engrafted human cells were localized in clusters surrounding the bile ducts, in close proximity to SDF-1-expressing epithelial cells, and differentiated into albumin-producing cells. Irradiation or inflammation increased SDF-1 levels and hepatic injury induced MMP-9 activity, leading to both increased CXCR4 expression and SDF-1-mediated recruitment of hematopoietic progenitors to the liver. Unexpectedly, HGF, which is increased following liver injury, promoted protrusion formation, CXCR4 upregulation, and SDF-1-mediated directional migration by human CD34+ progenitors, and synergized with stem cell factor. Thus, stress-induced signals, such as increased expression of SDF-1, MMP-9, and HGF, recruit human CD34+ progenitors with hematopoietic and/or hepatic-like potential to the liver of NOD/SCID mice. Our results suggest the potential of hematopoietic CD34+/CXCR4+cells to respond to stress signals from nonhematopoietic injured organs as an important mechanism for tissue targeting and repair.

Nomenclature of the finer branches of the biliary tree: Canals, ductules, and ductular reactions in human livers

The work of liver stem cell biologists, largely carried out in rodent models, has now started to manifest in human investigations and applications. We can now recognize complex regenerative processes in tissue specimens that had only been suspected for decades, but we also struggle to describe what we see in human tissues in a way that takes into account the findings from the animal investigations, using a language derived from species not, in fact, so much like our own. This international group of liver pathologists and hepatologists, most of whom are actively engaged in both clinical work and scientific research, seeks to arrive at a consensus on nomenclature for normal human livers and human reactive lesions that can facilitate more rapid advancement of our field. (HEPATOLOGY 2004; 39:1739–1745.)

Hepatic angiomyolipoma - A clinicopathologic study of 30 cases and delineation of unusual morphologic variants

Hepatic angiomyolipoma (AML) is frequently misdiagnosed. HMB-45 is a promising immunomarker for this tumor that leads to recognition of some AMLs with unusual morphology. The purpose of this collaborative study is to better define the morphologic variations of AML. Thirty AMLs were examined, including four biopsy specimens and two fine-needle aspirates. The diagnosis was confirmed by the presence of HMB-45-positive myoid cells. Almost half the cases were originally misdiagnosed as carcinomas or sarcomas. There was marked female predominance (25:5), and the mean age was 48.7 years (range 29-68). Three patients (10%) had evidence of tuberous sclerosis and all had renal AML. According to the line of differentiation and predominance of tissue components, the tumors was subcategorized into mixed, lipomatous (> or = 70% fat), myomatous (< or = 10% fat), and angiomatous type. The mixed type was the most common (11 resected cases), comprising sheets of epithelioid muscle cells admixed with islands of adipocytes, abnormal vessels, and frequently, hematopoietic cells. Six tumors (including three from biopsy specimens) were heavily fatty and showed predominantly adipocytes with epithelioid and short spindle myoid cells webbed between fat cells. Of 10 myomatous AMLs, five tumors showed a pure sinusoidal trabecular pattern and comprised mainly epithelioid cells. Typically, mature adipocytes were absent or scanty, but fat was seen as fine droplets within cytoplasm or as occasional large globules in sinusoids. Pelioid and inflammatory pseudotumor-like patterns were identified focally. Regarding cellular features of the myoid cells, most of the epithelioid cells were either eosinophilic or clear with spiderweb cell morphology. Three AMLs showed an almost purely oncocytic appearance with scanty fat. Large pleomorphic epithelioid cells existed as small foci. Spindle cells arranged in long fascicles were uncommon. D-PAS-positive globules were common around pelioid areas. Brown pigments with staining characteristics of hemosiderin and/or melanin were noted. In conclusion, we propose HMB-45-positive myoid cells as the defining criterion of hepatic AML, which is a tumor capable of dual myomatous and lipomatous differentiation and melanogenesis. Because of its protean morphologic appearance, recognition of the various variant patterns and cell types is important for a correct diagnosis, assisted by immunohistochemical confirmation with HMB-45. Trabecular and oncocytic cell tumors appear to stand out as distinctive subtypes.

Neoangiogenesis and sinusoidal "capillarization" in dysplastic nodules of the liver

The blood supply of hepatocellular carcinoma (HCC) is primarily arterial. Recent studies reported differences of vascular, especially arterial, supply among low- and high-grade dysplastic nodules and HCC. We assessed arterialization using monoclonal antibody specific for smooth muscle actin as well as simultaneous changes in sinusoidal capillarization in cirrhotic nodules, dysplastic nodules, and HCC. We immunohistochemically stained 56 cirrhotic nodules, 20 low-grade dysplastic nodules, 27 high-grade dysplastic nodules, and 20 HCCs for alpha smooth muscle actin (to identify unpaired arteries (i.e., arteries not accompanied by bile ducts) and CD34 (indicating sinusoidal capillarization). Distribution and number of unpaired arteries and distribution of sinusoidal capillarization were graded semiquantitatively. Unpaired arteries were rare in cirrhotic nodules, significantly more common in dysplastic nodules of both types (p < 0.00001), and most common in HCC. Sinusoidal capillarization was least common in cirrhotic nodules, significantly more common in dysplastic nodules (p < 0.0035), and most common in HCC. No topographic relationship between unpaired arteries and sinusoidal capillarization was identified. These findings showed that (1) distributions of sinusoidal capillarization and unpaired arteries in dysplastic nodules are intermediate between those in cirrhotic nodules and HCC, supporting dysplastic nodules as premalignant lesions; (2) unpaired arteries are histologically useful for distinguishing dysplastic nodules from large cirrhotic nodules; and (3) areas of sinusoidal capillarization within dysplastic nodules are unrelated to location of arterialization.

Combining Clinical, Pathology, and Gene Expression Data to Predict Recurrence of Hepatocellular Carcinoma

BACKGROUND & AIMS In approximately 70% of patients with hepatocellular carcinoma (HCC) treated by resection or ablation, disease recurs within 5 years. Although gene expression signatures have been associated with outcome, there is no method to predict recurrence based on combined clinical, pathology, and genomic data (from tumor and cirrhotic tissue). We evaluated gene expression signatures associated with outcome in a large cohort of patients with early stage (Barcelona-Clinic Liver Cancer 0/A), single-nodule HCC and heterogeneity of signatures within tumor tissues. METHODS We assessed 287 HCC patients undergoing resection and tested genome-wide expression platforms using tumor (n = 287) and adjacent nontumor, cirrhotic tissue (n = 226). We evaluated gene expression signatures with reported prognostic ability generated from tumor or cirrhotic tissue in 18 and 4 reports, respectively. In 15 additional patients, we profiled samples from the center and periphery of the tumor, to determine stability of signatures. Data analysis included Cox modeling and random survival forests to identify independent predictors of tumor recurrence. RESULTS Gene expression signatures that were associated with aggressive HCC were clustered, as well as those associated with tumors of progenitor cell origin and those from nontumor, adjacent, cirrhotic tissues. On multivariate analysis, the tumor-associated signature G3-proliferation (hazard ratio [HR], 1.75; P = .003) and an adjacent poor-survival signature (HR, 1.74; P = .004) were independent predictors of HCC recurrence, along with satellites (HR, 1.66; P = .04). Samples from different sites in the same tumor nodule were reproducibly classified. CONCLUSIONS We developed a composite prognostic model for HCC recurrence, based on gene expression patterns in tumor and adjacent tissues. These signatures predict early and overall recurrence in patients with HCC, and complement findings from clinical and pathology analyses.

A system of classifying microvascular invasion to predict outcome after resection in patients with hepatocellular carcinoma.

BACKGROUND & AIMS Hepatocellular carcinoma (HCC) recurs in approximately 70% of cases after resection. Vascular invasion by tumor cells can be classified as gross or microscopic (microvascular invasion [mVI]) and is a risk factor for recurrence. We examined a large cohort of patients with HCC who were treated by resection to identify features of mVI that correlated with recurrence and survival. METHODS We reviewed the records of all HCC resections performed at the Mount Sinai School of Medicine between January 1990 and March 2006 to identify those with mVI, established by histologic analysis. The numbers and sizes of vessels invaded, invasion of a vessel with a muscular wall, distance from the tumor, and satellite nodules were recorded. RESULTS Of the 384 patients who underwent resection for HCC, 131 (34.1%) met the entry criteria. The median follow-up period was 28.9 months. There were 68 recurrences and 54 deaths. In multivariate analysis, invasion of a vessel with a muscular wall predicted recurrence (hazard ratio, 1.8; P = .02), and invasion of a vessel with a muscular wall (hazard ratio, 2.2; P = .018) and invasion of a vessel that was more than 1 cm from the tumor (hazard ratio, 2.1; P = .015) predicted survival. A risk score that assigned points for the presence of each variable correlated with recurrence (P = .028) and survival (P < .0001). CONCLUSIONS A novel classification system that includes invasion of a vessel with a muscular wall and invasion of a vessel that is more than 1 cm from the tumor can accurately predict risk of recurrence and survival of patients with mVI after resection of HCC.

Integrative Molecular Analysis of Intrahepatic Cholangiocarcinoma Reveals 2 Classes That Have Different Outcomes

BACKGROUND & AIMS Cholangiocarcinoma, the second most common liver cancer, can be classified as intrahepatic cholangiocarcinoma (ICC) or extrahepatic cholangiocarcinoma. We performed an integrative genomic analysis of ICC samples from a large series of patients. METHODS We performed a gene expression profile, high-density single-nucleotide polymorphism array, and mutation analyses using formalin-fixed ICC samples from 149 patients. Associations with clinicopathologic traits and patient outcomes were examined for 119 cases. Class discovery was based on a non-negative matrix factorization algorithm and significant copy number variations were identified by Genomic Identification of Significant Targets in Cancer (GISTIC) analysis. Gene set enrichment analysis was used to identify signaling pathways activated in specific molecular classes of tumors, and to analyze their genomic overlap with hepatocellular carcinoma (HCC). RESULTS We identified 2 main biological classes of ICC. The inflammation class (38% of ICCs) is characterized by activation of inflammatory signaling pathways, overexpression of cytokines, and STAT3 activation. The proliferation class (62%) is characterized by activation of oncogenic signaling pathways (including RAS, mitogen-activated protein kinase, and MET), DNA amplifications at 11q13.2, deletions at 14q22.1, mutations in KRAS and BRAF, and gene expression signatures previously associated with poor outcomes for patients with HCC. Copy number variation-based clustering was able to refine these molecular groups further. We identified high-level amplifications in 5 regions, including 1p13 (9%) and 11q13.2 (4%), and several focal deletions, such as 9p21.3 (18%) and 14q22.1 (12% in coding regions for the SAV1 tumor suppressor). In a complementary approach, we identified a gene expression signature that was associated with reduced survival times of patients with ICC; this signature was enriched in the proliferation class (P < .001). CONCLUSIONS We used an integrative genomic analysis to identify 2 classes of ICC. The proliferation class has specific copy number alterations, activation of oncogenic pathways, and is associated with worse outcome. Different classes of ICC, based on molecular features, therefore might require different treatment approaches.

Aggressive surgical treatment of intrahepatic cholangiocarcinoma: predictors of outcomes

BACKGROUND Intrahepatic cholangiocarcinoma (ICC) is the second most common primary liver cancer and constitutes 10% of primary liver malignancies. Surgery is the optimal therapy; the majority of the patients will require extensive resections that are associated with significant morbidity. METHODS We retrospectively studied the records of 26 patients who underwent exploratory laparotomy for intrahepatic cholangiocarcinoma between June 1991 and December 1997 at the Mount Sinai Hospital. Patients with perihilar (Klatskin) tumors were excluded. All patients were considered resectable based on CT or MRI findings. Patients with positive margins or nodal invasion received adjuvant chemotherapy and radiation. RESULTS Sixteen patients underwent 18 resections; in 10 patients the tumors were unresectable at laparotomy and only biopsy was performed. The mean age (62 versus 53 years) was significantly higher, and the mean total bilirubin level (0.71 versus 6.17 mg/dL) was significantly lower in the resected group (p=0.031 and 0.017, respectively). No patient with a total bilirubin over 1.2 mg/dL was found to be resectable. Median actuarial survivals were 42.9+/-8.9 months for resectable and 6.7+/-3.6 months for unresectable patients (p=0.005). Positive margins were associated with significantly shorter disease-free survival. But resected patients with positive margins survived significantly longer than those who were unresectable. Tumor size, presence of satellite nodules, and degree of tumor necrosis on histologic examination were significant predictors of outcomes. Survival among patients receiving adjuvant therapy was not significantly altered. CONCLUSIONS We conclude that an aggressive surgical approach is warranted in patients with ICC because resection offers the only hope for longterm survival. Our findings emphasize the importance of achieving tumor-free margins. Noncurative resection offers a survival advantage over no resection. Histologic examination of resected specimens can help select patients with poor prognoses.

Frequent inactivation of the tumor suppressor Kruppel-like factor 6 (KLF6) in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a leading cause of cancer death worldwide, reflecting incomplete characterization of underlying mechanisms and lack of early detection. Krüppel‐like factor 6 (KLF6) is a ubiquitously expressed zinc finger transcription factor that is deregulated in multiple cancers through loss of heterozygosity (LOH) and/or inactivating somatic mutation. We analyzed the potential role of the KLF6 tumor suppressor gene in 41 patients who had HCC associated with hepatitis C virus (16 patients), hepatitis B virus (12 patients, one of whom was coinfected with hepatitis C virus), and other etiologies (14 patients) by determining the presence of LOH and mutations. Overall, LOH and/or mutations were present in 20 (49%) of 41 tumors. LOH of the KLF6 gene locus was present in 39% of primary HCCs, and the mutational frequency was 15%. LOH and/or mutations were distributed across all etiologies of HCC evaluated, including patients who did not have cirrhosis. Functionally, wild‐type KLF6 decreased cellular proliferation of HepG2 cells, while patient‐derived mutants did not. In conclusion, we propose that KLF6 is deregulated by loss and/or mutation in HCC, and its inactivation may contribute to pathogenesis in a significant number of these tumors. (HEPATOLOGY 2004;40:1047–1052.)

Intrahepatic Cholangiocarcinoma: New Insights in Pathology

Cholangiocarcinomas are malignant tumors that derive from cholangiocytes of small intrahepatic bile ducts or bile ductules (intrahepatic cholangiocarcinoma; ICC), or of large hilar or extrahepatic bile ducts (extrahepatic cholangiocarcinoma; ECC). ICC and ECC differ in morphology, pathogenesis, risk factors, treatment, and prognosis. This review focuses on ICC, which is rising in incidence with the emergence of hepatitis C virus (HCV) infection as a risk factor. The authors examined 73 ICC, which were resected at The Mount Sinai Medical Center in New York City, and reviewed the literature. The tumors were categorized into classical and nonclassical ICCs based on histopathology. Classical ICCs (54.8%) were characterized by a tubular, glandular, or nested pattern of growth, were significantly associated with tumor size of more than 5 cm and the absence of underlying liver disease and/or advanced fibrosis. Nonclassical ICCs (45.2%) consisted of tumors with trabecular architecture, tumors that exhibited features of extrahepatic carcinomas, and carcinomas considered to be derived from hepatic progenitor cells, i.e., combined hepatocellular/cholangiocarcinomas and cholangiolocellular carcinomas (ductular type of ICC). They were smaller and often arose in chronic liver disease, mostly HCV infection, and/or with significant fibrosis. The role of immunohistochemistry in the diagnosis of ICC and the importance of the new American Joint Committee on Cancer Staging System for ICC are also discussed.