Variable Antigen Expression in Hepatoblastomas

Downregulation of transcription factor GATA4 sensitizes human hepatoblastoma cells to doxorubicin-induced apoptosis

Hepatoblastoma, the most common type of pediatric liver cancer, is treated with a combination of surgery and chemotherapy. An essential drug in the treatment of hepatoblastoma is doxorubicin, which in high doses is cardiotoxic. This adverse effect is due to downregulation of cardiac expression of transcription factor GATA4, leading in turn to diminished levels of anti-apoptotic BCL2 (B-cell lymphoma 2) protein family members. GATA4 is also expressed in early fetal liver, but absent from normal postnatal hepatocytes. However, GATA4 is highly expressed in hepatoblastoma tissue. In this study, we assessed the role of GATA4 in doxorubicin-induced apoptosis of hepatoblastoma cells. Herein, we demonstrate that doxorubicin decreases GATA4 expression and alters the expression pattern of BCL2 family members, most profoundly that of BCL2 and BAK, in the HUH6 hepatoblastoma cell line. Silencing of GATA4 by siRNA prior to doxorubicin treatment sensitizes HUH6 cells to the apoptotic effect of this drug by further shifting the balance of BCL2 family members to the pro-apoptotic direction. Specifically, expression levels of anti-apoptotic BCL2 were decreased and pro-apoptotic BID were increased after GATA4 silencing. On the whole, our results indicate that since high endogenous levels of transcription factor GATA4 likely protect hepatoblastoma cells from doxorubicin-induced apoptosis, these cells can be rendered more sensitive to the drug by downregulation of GATA4.

A case of hepatoblastoma misdiagnosed as combined hepatocellular carcinoma and cholangiocarcinoma in an adult

Hepatoblastoma usually occurs in children under the age of 2 years, with very few cases reported in adults. We experienced a case of adult hepatoblastoma in a 36-year-old female with chronic hepatitis B. She had experienced sudden onset abdominal pain. Her serum alpha-fetoprotein level was markedly elevated, and abdominal CT showed a 9-cm mass with internal hemorrhage in the right hepatic lobe with hemoperitoneum, so an emergency hepatic central bisectionectomy was performed. The initial histologic examination revealed that the mass mimicked combined hepatocellular carcinoma and cholangiocarcinoma with spindle-cell metaplasia of the cholangiocarcinoma element. Follow-up abdominal CT performed 3 months later showed a 5.5-cm metastatic mass in the left subphrenic area. Laparoscopic splenectomy with mass excision was performed, and hepatoblastoma was confirmed histologically. A histologic re-examination of previously obtained surgical specimens also confirmed the presence of hepatoblastoma. Metastatic hepatoblastoma was found at multiple sites of the abdomen during follow-up, and so chemotherapy with cisplatin, 5-fluorouracil (5-FU), and vincristine was applied, followed by carboplatin and doxorubicin. Despite surgery and postoperative chemotherapy, she died 12 months after symptom onset.

CD99 is upregulated in placenta and astrocytomas with a differential subcellular distribution according to the malignancy stage

In the present study, we searched for genes highly expressed in placenta and that could contribute to the establishment and maintenance of a malignant phenotype in different types of tumours, and in astrocytomas in particular. We employed a strategy based on the integration of in silico data from previously generated massively parallel signature sequencing and public serial analysis of gene expression databases. Among 12 selected genes, CD99 exhibited the highest relative mRNA expression in GBM compared to non-neoplastic brain tissues. In a larger cohort of astrocytic tumours, we further demonstrated increased CD99 expression in all malignant grades, with GBMs showing the highest values. These findings were confirmed at the protein level by Western blotting and immunohistochemistry. Additionally, we demonstrated the CD99 localisation profile in astrocytic tumours. Interestingly, CD99 expression was confined to the cytoplasm or membrane in more malignant astrocytomas, in contrast to non-neoplastic brain tissue or non-infiltrative pilocytic astrocytoma, which showed no obvious staining in these structures. Comparison of three GBM cell lines revealed higher CD99 expression at the membrane and higher migratory capacity in the A172 and U87MG lines, but lower CD99 expression and no migratory ability in the T98 line. Knocking down CD99 expression by siRNA decreased significantly the migration of both cell lines. These integrated CD99 gene and protein expression results suggest that CD99 expression in astrocytomas of different malignant grades might contribute to the infiltrative ability and support the importance of CD99 as a potential target to reduce infiltrative astrocytoma capacity in migration and invasion.

Effect of shRNA targeting mouse CD99L2 gene in a murine B cell lymphoma in vitro and in vivo

Mouse CD99 antigen-like 2 (mCD99L2) has previously been confirmed to be expressed in murine B lymphoma (A20) cells by our group. The present study aimed to establish a mCD99L2‑downregulated A20 cell line and to investigate the effect of shRNA targeting mCD99L2 in A20 cells in vitro and in vivo. Four pLenti6/mCD99L2 expression vectors containing the mCD99L2 shRNA-expressing cassette were constructed, transfected into A20 cells and stable mCD99L2-downregulated A20 subclones, termed A20-mCD99L2- cells, were established and identified by quantitative PCR and western blot analysis. Light and transmission electron microscopy, MTT assay, flow cytometry and immunofluorenscence labeling were used to observe the morphological, biological and phenotypic characteristics in vitro. Some of the A20-mCD99L2- cells exhibited H/RS‑cell like morphology, a decreased proliferative ability, a prolonged G2 phase and increased CD30 and CD15 expression. Upon injecting cells into nude or immunocompetent BALB/c mice, tumorigenesis, tumor growth, morphology and phenotypes in vivo were observed. A20-mCD99L2- cells induced tumors in nude and BALB/c mice, but with less potency in the latter compared with the controls. Similar morphological, biological and phenotypic characteristics were observed in the A20-mCD99L2- cell-induced tumors as those in vitro. Several cytokines including CD30T, IL-12p40/p70, IL-3, IFN-γ, CXCL16, MIP-1α and CD40 were upregulated following mCD99L2 downregulation when detected using antibody arrays. The results from western blot analysis indicated that the regulation of mCD99L2 expression may involve the activated nuclear factor-κB pathway in the murine B lymphoma cells. The present study provides data for further investigation into the mCD99L2 gene in tumor cells.

Current issues and controversies in the classification of pediatric hepatocellular tumors

Systematic histopathologic examination of hepatoblastoma specimens from patients enrolled in therapeutic protocols has allowed the identification of clinically relevant histologic subtypes that are being incorporated into risk stratification systems. Genetic and molecular studies have documented recurrent chromosomal abnormalities and aberrant activation of developmental, and oncogenic signaling pathways in hepatoblastoma. Molecular profiling has also identified molecular subclasses and gene signatures that could be used to stratify hepatoblastoma patients. Future international collaboration is needed to develop consensus pathology classifications, and to progressively incorporate genetic and molecular biomarkers into therapeutic pediatric liver tumors protocols.

Teratoid Hepatoblastoma With Abundant Neuroendocrine and Squamous Differentiation With Extensive Parenchymal Metastasis

Teratoid hepatoblastoma is a rare histologic subtype accounting for 4% to 10% of all hepatoblastomas and is characterized by the presence of divergent differentiation, including squamous, mucinous, melanocytic, cartilaginous, osseous, skeletal muscle, and neural elements. It is postulated that the teratoid elements might derive from multipotential less-differentiated stem cells. Teratoid hepatoblastoma responds poorly to chemotherapy and therefore recognition of this variant has prognostic implications. We describe a 1½-year-old child with teratoid hepatoblastoma characterized by unusual clinical and morphologic patterns including prominent neuroendocrine and squamous differentiation.

Hepatoblastoma in a cat

Hepatoblastomas are neoplasms that originate from putative pluripotential stem cells of the liver. A hepatic mass from an 8-year-old Abyssinian cat was composed of cords and sheets of neoplastic cells, with scattered rosettes and small ductal structures. Most neoplastic cells had a pale eosinophilic cytoplasm and a round to ovoid nucleus. The tumor also had short spindle cells with an oval nucleus. Immunohistochemically, neoplastic cells were weakly positive for embryonic hepatocellular markers, such as alpha-fetoprotein and cytokeratin (CK) 8/18, but negative for the hepatocellular marker Hepatocyte Paraffin 1. The cells were also positive for CD56/neural cell adhesion molecule and for the biliary epithelial markers CK 7, CK 8/18, CK CAM5.2, and vimentin, but negative for CK 20. Some neoplastic cells expressed neuroectodermal or neuroendocrine markers, such as protein gene product 9.5 and synaptophysin, but were negative for chromogranin A and not argyrophilic by the Grimelius technique. The cat died soon after the biopsy without clinical improvement.

Equine Primary Liver Tumors: A Case Series and Review of the Literature

Hepatoblastoma (HB) is an uncommon pediatric liver tumor in humans and horses. In humans, HB is most frequently diagnosed in fetuses, neonates, and young children, whereas hepatocellular carcinoma (HCC) affects juvenile and adult humans. Hepatoblastoma in the horse is rare, with only 9 reported cases. Affected horses ranged in age from late-term aborted fetuses to 3 years. The current study describes 3 new cases of primary liver tumors in horses and reviews findings in relation to other reports on this condition. Tumors classified as HB were identified in a male Standardbred aborted fetus and in a 4-year-old Thoroughbred filly. Hepatocellular carcinoma was diagnosed in a 15-month-old Paint filly. In the Standardbred fetus, the tumor was only present in the liver. In the Thoroughbred and Paint fillies, primary tumors were in the right liver lobe and at the hilus, respectively, and there were metastases to other lobes (HB) and mesenteric lymph nodes (HCC). Tumors were sharply demarcated from adjacent tissue, nonencapsulated, compressive, and invasive. Consisting of cords and nests, or disorganized sheets of epithelial cells, tumors had variable stromal and vascular components. The fetal tumor contained areas of smaller, less differentiated cells with a pronounced mesenchymal component interpreted to be embryonal hepatic tissue. Diagnoses were based on tumor histomorphologic features, resemblance to hepatocyte developmental stages, age of the animal, and patterns of metastasis. Tumors classified as HB were α-fetoprotein immunoreactive. Primary hepatic tumors in the horse are diverse in morphology and include subtypes compatible with classification criteria applied to human tumors.

Nested (ossifying) stromal epithelial tumor of the liver: case report

Nested stromal-epithelial tumor (NSET) of the liver is an extremely rare primary hepatic tumor with uncertain malignant potential. To date, only 11 cases have been described. We describe the case of a 2 1/2-year-old girl with an incidental liver mass. The mass was discovered on follow-up abdominal imaging for asymptomatic hydronephrosis diagnosed on antenatal ultrasound. Needle biopsy showed a mixed stromal and epithelial process in a nested pattern, with foci of ossification and no significant pleomorphism or necrosis. The nest cells stained with WT-1, cytokeratin 18, and CD56. Ossifying stromal epithelial tumor of the liver was strongly suspected. The findings were confirmed in the subsequent partial hepatectomy specimen. To our knowledge, this is the 12th case of NSET in the English-language literature and the 3rd case of NSET associated with genitourinary system abnormalities. Possible associations with dysregulated WT-1 expression are discussed.