Takashi Nikaido

Immunocytochemical and ultrastructural studies of the histogenesis of Ewing's sarcoma and putatively related tumors

The histogenesis of Ewings sarcoma (EW) and extraskeletal Ewings sarcoma (EEW) is still disputable. Their relationship to the so‐called Askins tumor, neuroectodermal tumor of bone, and peripheral neuroblastoma remains to be established. In an attempt to clarify these points, immunocytochemical and ultrastructural studies were done on tissues from 14 cases of EW, 4 cases of EEW, and 9 cases of primitive neuroectodermal tumor (PNET) and compared with neuroblastoma and olfactory neuroblastoma. Six tumors categorized initially as EW and EEW on biopsy, turned out to be PNET by extensive histologic and/or ultrastructural observations. Abundant glycogen was recognized not only in 16 of 18 cases of EW and EEW, but also in seven of nine cases of PNET. Fine fibrillar cell processes were seen between tumor cells, at least in limited areas even in cases of EW and EEW. Immunocytochemically, neuron‐specific enolase (NSE), neuroblastoma cell surface antigen (NBCA), neuron cell surface antigen (NCSA), and neurofilament (NF) were demonstrated not only in neuroblastoma, but also frequently in cases of EW, EEW, and PNET. The results seem to suggest that EW and EEW represent the most immature forms of neuroectodermal tumor. Electron microscopic study showed predominantly primitive cells with occasional areas of cell processes, neurosecretory granules, and microtubules, suggesting a neuroectodermal origin.

Expression of an activated mammalian target of rapamycin (mTOR) in gastroenteropancreatic neuroendocrine tumors

AimsGastroenteropancreatic neuroendocrine tumors are rare, and the current WHO classification divides this tumor entity into well-differentiated (neuro)endocrine tumors, well-differentiated (neuro)endocrine carcinomas, and poorly differentiated (neuro)endocrine carcinomas. Poorly differentiated (neuro)endocrine carcinoma is extremely aggressive, and no appropriate therapeutic approach has been established. The mammalian target of rapamycin (mTOR), an important regulator of cell proliferation and protein translation, is activated in various malignancies. Recent phase II trial has revealed the efficacy of mTOR inhibitor (RAD001; everolimus) against low-to-intermediate grade neuroendocrine tumors. However, the beneficial role of mTOR inhibitor against poorly neuroendocrine carcinoma remains uncertain. The purpose of the present study was to determine the activation of mTOR in gastropancreatic neuroendocrine tumors, especially in poorly differentiated neuroendocrine carcinomas.MethodsExpression of p-mTOR(Ser2448) was assessed by immunohistochemistry in 20 gastropancreatic neuroendocrine tumors (seven well-differentiated neuroendocrine tumors, four well-differentiated neuroendocrine carcinomas, and nine poorly differentiated neuroendocrine carcinomas). Double immunohistochemistry was performed with p-Akt for patients with high p-mTOR expression.ResultsExpression of mTOR was seen in 9 (45%) of 20 gastroenteropancreatic neuroendocrine tumors. High expression of p-mTOR was seen in 6 (67%) of 9 poorly differentiated neuroendocrine carcinomas which was higher than the expression rate of well-differentiated neuroendocrine tumors and carcinomas, 3 (27%) of 11. All large cell neuroendocrine carcinomas showed high p-mTOR expression. Some tumor cells showed positive staining for p-mTOR co-expressed p-Akt.ConclusionsHigh expression rate of p-mTOR in poorly differentiated neuroendocrine carcinomas (large-cell type) may suggest the potential role of mTOR inhibitors as effective therapeutic agents for this highly malignant disease.

CD151 dynamics in carcinoma-stroma interaction: integrin expression, adhesion strength and proteolytic activity.

A member of tetraspanin CD151 is a scaffold protein of laminin-binding integrins and it plays an important role in stable interaction between cells and basement membrane. Although the upregulation of CD151 in tumor cells is thought to accelerate tumor invasion and metastasis, detailed pathological investigation on CD151 and its association with integrins has not been well documented, yet. In the present study, we showed that the expression levels of CD151 and its associated integrin subunits in epidermal carcinoma cell HSC5 were higher than those in immortalized epidermal cell HaCaT. By the stimulation of epidermal growth factor, CD151 was dissociated from cell surface and dispersed in the cytoplasm, and α3β1 integrin was concomitantly internalized. To understand the significance of CD151 in tumor cell dynamics, CD151 in HSC5 was knocked down (HSC5CD151−), and the expression of integrin subunits and matrix metalloproteinases (MMPs) were investigated. In HSC5CD151−, striking morphological alteration on Matrigel and laminin, and cytoskeletal rearrangements were demonstrated. α3β1 integrin was internalized in part, and α6β4 integrin was re-distributed from basal site to cell periphery. Quantitative RT-PCR, Western blot and zymography revealed that the expression levels of MMP2, MMP7 and MMP9 were markedly downregulated in HSC5CD151−. Immunoprecipitation assay demonstrated that MMP7 was co-immunoprecipitated with CD151. In double stainings, MMP7 was colocalized with CD151 at the leading edge of lamellipodia under migratory status. These results elucidated the importance of CD151 as one of the key molecules for integrin-dependent carcinoma–stroma interaction. It is indicated that CD151 might contribute not only to cell stabilization by associating with adhesion complexes but also to cell migration by inducing integrins re-localization and MMPs production.

Hepatoid carcinoma of the ovary: a report of three cases admixed with a common surface epithelial carcinoma.

&NA; Hepatoid carcinoma of the ovary is an ovarian carcinoma that has phenotypic properties in common with hepatocellular carcinomas. However, the extent of the tumor cells’ similarity to and their difference from hepatocytes is largely unknown. In addition, the precursor cell of origin for hepatoid carcinoma of the ovary has not been identified. Three cases of alpha‐fetoprotein‐producing hepatoid carcinoma of the ovary that were admixed with an adenocarcinoma of common surface epithelial type are reported. The hepatoid carcinomas had a trabecular architecture with canaliculi detected by polyclonal (but not monoclonal) anticarcinoembryonic antigen antibodies. A hepatic phenotype in the hepatoid tumor cells was further supported by the production of albumin mRNA by in situ hybridization. The adenocarcinomas in the three cases were mucinous (Case 1), serous (Case 2), and endometrioid (Case 3), respectively. The cytokeratin (CK) profile in both the hepatoid and adenocarcinomatous components was CK18+/CK19+/CK20±, whereas normal and neoplastic hepatocytes were CK18+/CK19‐/CK20‐. Although this study supports a hepatic phenotype in ovarian hepatoid carcinoma, the CK profile of hepatoid carcinoma differs from that of normal and neoplastic hepatocytes but resembles that of the associated common epithelial adenocarcinoma. These findings suggest that hepatoid carcinoma of the ovary is probably derived from carcinomas of surface epithelial origin by a process of neometaplasia or transdifferentiation.

PRIMITIVE NEUROECTODERMAL TUMORS OF BONE AND SOFT TISSUE : WITH REFERENCE TO HISTOLOGIC DIFFERENTIATION IN PRIMARY OR METASTATIC FOCI

Primitive neuroectodermal tumors (PNET) of the bone and soft tissue were reviewed by immunohistochemistry and partly by morphometry, focusing particularly on histologic changes in recurrent or metastatic foci, in order to elucidate their probable histogenetic relationship with Ewings sarcoma (ES) and its extraskeletal counterpart (EES). Eleven cases of bone tumor (average patient age; 15.1 yr) and 12 cases of soft tissue tumor (average patient age; 22.1 yr) which disclosed unequivocal Homer Wright rosettes and/or at least foci of ganglion cell differentiation either in a given primary tumor or metastatic (or recurrent) foci were selected from small round cell tumors primarily categorized as ES or EES. Most of the cases for which follow up biopsy samples were available disclosed prominent Homer Wright rosettes in the metastases, whereas the primary tumors showed features of ES and lacked rosettes. In only one case, Homer‐Wright rosettes were absent in the metastatic tumor. Most cases had been treated by combined intensive chemotherapy and radiotherapy, which might have influenced cell differentiation. Neural markers (neuron‐specific enolase, neurofilament protein and others) were positive in most cases. Three cases with otherwise typical histologic features of ES or EES showed minute foci of ganglion cell differentiation, as confirmed by morphometry and neural markers. These results suggest that ES (or EES) and PNET are histo‐genetically related, but represent different stages of cell differentiation.

Spindle cell hemangioendothelioma: An immunohistochemical and flow cytometric study of six cases

Six cases of spindle cell hemangioendothelioma (SCH) are presented with immunohistochemical and flow cytometric analyses. One case was associated with Maffuccis syndrome. All lesions were solitary or multifocal in the extremities, and prepresentation duration ranged from years to decades. One case recurred but none had metastases. Histologically, in four of the six cases the main lesions appeared to arise within vessels, predominantly muscular vessels. All lesions consisted of cavernous hemangiomalike areas and solid cellular areas resembling Kaposis sarcoma. Cellular atypia was minimal. At the periphery of the lesions, a cluster of large thick or thin walled, and probably malformed, vessels were observed. Immunohistochemically, factor‐VIII related antigen, CD34, vimentin, and lectin binding Ulex europaeus agglutinin 1 stained endothelial cells lining vascular channels, and vacuolated, or epithelioid cells. Spindle cells in the solid areas were negative for these endothelial markers except for vimentin, but showed divergent positive immunoreactions of HHF35, alpha‐smooth muscle actin, desmin, and collagen type IV. Five cases were diploid and one was aneuploid. There was no significant correlation among DNA ploidy, S‐phase fraction, and local recurrence in SCH although the number of cases examined was small. These results suggest SCH may be a benign lesion, probably a reactive process, rather than a low‐grade angiosarcoma.

The expression of NeuroD and mASH1 in the gastroenteropancreatic neuroendocrine tumors

Gastroenteropancreatic neuroendocrine tumors are uncommon and their tumor biology has not been well elucidated to date. Currently the WHO classification is widely used for the diagnosis and distinction of this tumor entity, which is sometimes cumbersome. Although neuroendocrine tumor markers do exist (ie chromograninA, synaptopyhsin, etc), sensitive and specific markers that accurately predict tumor growth and tumor behavior are still absent. In the present study, we assessed the expression of transcription factors (NeuroD and mASH1) essential for the normal fetal neuronal development in 33 gastroenteropancreatic neuroendocrine tumor patients (12 well-differentiated neuroendocrine tumors, 7 well-differentiated neuroendocrine carcinomas, and 14 poorly differentiated neuroendocrine carcinomas). NeuroD was less expressed in poorly differentiated neuroendocrine carcinoma (small-cell type) compared to well-differentiated neuroendocrine tumor (carcinoid) by reverse transcription–polymerase chain reaction. Immunohistochemical staining revealed that mASH1 was highly (sensitivity of 71%) and specifically (specificity of 95%) expressed in poorly differentiated neuroendocrine carcinoma. High NeuroD expression was seen in all well-differentiated neuroendocrine carcinoma and tumor (carcinoid) patients. Low NeuroD expression was seen in 36% (5 of 14) of poorly differentiated neuroendocrine carcinoma patients, which was associated with significant shorter overall survival. The expression pattern of these transcription factors may represent the biological and pathophysiological difference of gastroenteropancreatic neuroendocrine tumors and may become a new marker for the distinction of gastroenteropancreatic neuroendocrine tumors.

Case report 679

An infrequently encountered case of well-differentiated CLOS containing dedifferentiated tumor foci in a 28-year-old Japanese man is reported. The patient died from widespread metastases with a microscopic appearance identical to the anaplastic dedifferentiated lesions of the original tumor. This is, to our knowledge, the first report of a case of CLOS with dedifferentiation at the time of initial surgery. The literature concerning CLOS was reviewed and the diagnostic features of CLOS discussed.

Sonic hedgehog-Gli1 signaling pathway might become an effective therapeutic target in gastrointestinal neuroendocrine carcinomas

Gastrointestinal neuroendocrine carcinomas (NECs) are extremely aggressive and poorly prognostic. We showed previously that human achaete-scute homologue gene 1 (hASH1), a basic helix-loop-helix transcription factor regulated by Notch, was aberrantly expressed in NECs. To date, no effective therapeutic strategies for NECs have been investigated. Notch, Wnt and Hedgehog (Hh) signalings are important for stem cell self-renewal and carcinogenesis in the gastrointestinal epithelium. In this study, we showed that Hh signaling was clearly upregulated in NECs in Gli1-dependent manner. Specific therapeutic effects of cyclopamine on NECs were also demonstrated. RT-PCR showed that among eight frozen samples (three NECs, one carcinoid tumor, three adenocarcinomas and one normal mucosa), the band intensities of Gli1 were the strongest in NECs, moderately strong in a carcinoid tumor, very weak in adenocarcinomas and undetectable in a normal mucosa. In real-time RT-PCR, the expression levels of Gli1 in NECs were 108.4, 28.6 and 16.3 times higher than that in an adenocarcinoma. In immunohistochemistry using 25 paraffin-embedded tissues, all twelve NECs and three of six carcinoid tumors showed positive stainings for Gli1, whereas six of seven adenocarcinomas were negative. In vitro, RT-PCR showed that NEC cell lines expressed Gli1 mRNA significantly. Administration of cyclopamine suppressed cell proliferation and invasion, and induced apoptosis in NECs. In cyclopamine-treated NECs, downregulation of Gli1, Ptch1, Snail and hASH1, and upregulation of E-cadherin were demonstrated at mRNA levels. Such effects were not observed in a Gli1-negative colonic adenocarcinoma cell line or in control alkaloid-treated NECs. Hh signaling may play a crucial role in the pathophysiology of NECs. Blockade of Hh pathway using cyclopamine or its synthetic derivatives might open an effective therapeutic strategy to NECs, not only by suppressing tumor viability but also by altering tumor cell nature.

Histopathologic Diagnostic and Histogenetic Problems in Malignant Soft Tissue Tumors

More than 10 years have passed since immunohistochemistry was introduced with the expectation of enabling reliable objective differential diagnosis in soft tissue tumors difficult to diagnose on light microscopic examination, and of the analysis of the cell origin of tumors of unknown histogenesis. At present, much immunophenotypic information can be obtained on routine surgical pathology of soft tissue tumors and one can ascertain the diagnosis with objective evidence on many occasions. On the other hand, newly obtained findings may give rise to other diagnostic or histogenetical problems. For example, malignant fibrous histiocytoma, the concept of which was first proposed by OBrien and Stout (1) in 1964 and supported by many investigators (2-10) after that, is now regarded as a definite clinicopathologic entity. However, this is still a controversial tumor in terms of its differential diagnosis (1 1, 12) and histogenesis even after extensive ultrastructural (1 3-1 7), immunohistochemical(l8-22) and xenograft studies (23, 24). Interesting but difficult problems in interpret-