Kit receptor tyrosine kinase dysregulations in feline splenic mast cell tumours.

This study investigated Kit receptor dysregulations (cytoplasmic immunohistochemical expression and/or c-KIT mutations) in cats affected with splenic mast cell tumours. Twenty-two cats were included. Median survival time was 780 days (range: 1-1219). An exclusive splenic involvement was significantly (P = 0.042) associated with longer survival (807 versus 120 days). Eighteen tumours (85.7%) showed Kit cytoplasmic expression (Kit pattern 2, 3). Mutation analysis was successful in 20 cases. Fourteen missense mutations were detected in 13 out of 20 tumours (65%). Eleven (78.6%) were located in exon 8, and three (21.6%) in exon 9. No mutations were detected in exons 11 and 17. Seven mutations corresponded to the same internal tandem duplication in exon 8 (c.1245_1256dup). Although the association between Kit cytoplasmic expression and mutations was significant, immunohistochemistry cannot be considered a surrogate marker for mutation analysis. No correlation was observed between c-Kit mutations and tumour differentiation, mitotic activity or survival.

Elevated serum thymidine kinase activity in canine splenic hemangiosarcoma*.

Thymidine kinase 1 (TK1) is a soluble biomarker associated with DNA synthesis. This prospective study evaluated serum TK1 activity in dogs presenting with hemoabdomen and a splenic mass. An ELISA using azidothymidine as a substrate was used to evaluate TK1 activity. Sixty-two dogs with hemoabdomen and 15 normal controls were studied. Serum TK1 activity was significantly higher in dogs with hemangiosarcoma (HSA) than in normal dogs (mean ± SEM = 17.0 ± 5.0 and 2.01 ± 0.6, respectively), but not dogs with benign disease (mean ± SEM = 10.0 ± 3.3). Using a cut-off of 6.55 U/L, TK activity demonstrated a sensitivity of 0.52, specificity of 0.93, positive predictive value of 0.94 and negative predictive value of 0.48 for distinguishing HSA versus normal. When interval thresholds of <1.55 and >7.95 U/L were used together, diagnostic utility was increased. Serum TK1 evaluation may help to discriminate between benign disease and HSA in dogs with hemoabdomen and a splenic mass.

Matrix metalloproteinase-1 expression in splenic angiosarcoma metastasizing to the serous membrane.

Angiosarcoma involving the serous membrane may mimic mesothelioma; therefore, the term "pseudomesotheliomatous angiosarcoma" has been suggested for this entity. However, the pathogenesis of pseudomesotheliomatous angiosarcoma remains unclear. Here, we report an autopsy case of splenic angiosarcoma, which systemically metastasized to the serous membrane of both the peritoneum and pleura, closely resembling a mesothelioma. The spindle-shaped tumor cells exhibited marked invasion of the lymphatic vessels and invaded the serous membrane causing thickening of the fibrous tissues like desmoplastic mesothelioma. In the present case, immunohistochemical staining showed that the tumor expressed not only the endothelial cell markers, such as CD31, vascular endothelial growth factor receptor 3, and podoplanin (D2-40), but also matrix metalloproteinase-1 (also known as collagenase-1), which is known to increase the invasiveness of mesothelioma cells. MMP-1 expression was not observed in the other cases of angiosarcoma, examined. This tumor might systemically metastasize to the serous membrane via the lymphatic route and might generate the fibrous stroma aided by the matrix metalloproteinase-1.

The implication of N-acetylglucosaminyltransferase V expression in gastric cancer.

OBJECTIVE: N-acetylglucosaminyltransferase V (GnT-V) is a key enzyme that catalyzes beta(1-6) branching of N-acetylglucosamine on N-glycan of cell proteins, some of which are linked with metastasis. GnT-V expression was studied immunohistochemically in gastric cancer to compare clinicopathological parameters and evaluate the role of GnT-V in the prognosis of gastric cancer. METHODS: Immunohistochemistry was carried out to detect GnT-V expression in 50 advanced gastric cancer tissues where the depth of invasion exceeded the subserosa, and the relationship between GnT-V expression and various clinicopathological factors, including survival, was analyzed. RESULTS: GnT-V was expressed in 23 (46%) gastric cancer tissues. GnT-V expression was significantly correlated with lymph node metastases, peritoneal dissemination and liver metastases, respectively (p = 0.005, p = 0.013 and p = 0.023). Patients with GnT-V-positive gastric cancer had a significantly shorter survival than those without GnT-V expression (5-year survival rate: 31.2 and 54.4%, respectively; p = 0.045). CONCLUSION: GnT-V expression is correlated with a poor prognosis in gastric cancer patients due to metastases.

Extracellular matrix metalloproteinase inducer (EMMPRIN) and matrix metalloproteinases (MMPs) as regulators of tumor-host interaction in a spontaneous metastasis model in rats.

EMMPRIN has a role in invasion and metastasis through the induction of MMPs and the consequent modulation of cell-substrate and cell-cell adhesion processes. The present study evaluates the expression of EMMPRIN protein and MMP-2/9 activity in tumor and parenchymal cells in a spontaneous metastasis model in rats. Moreover, we explore the regulation of EMMPRIN and MMP-9 by tumor-epithelial cell interactions in vitro. By zymography, we observed an increased proMMP-9 expression in both metastasized liver and spleen samples from tumor bearing rats. Immunohistochemical studies showed EMMPRIN-positive tumor cells in tumor biopsies as well as in spleen and liver samples from tumor bearing rats. Interestingly, a significant increase in EMMPRIN expression in hepatic cells was also detected. The regulation of EMMPRIN expression in tumor and liver cells in response to tumor-host interaction was investigated in vitro through a tumor cell line culture on extracellular matrix (ECM) molecules or in co-culture with normal rat liver cells (BRL3A cells). No significant changes in EMMPRIN expression were detected in tumor cells cultured on ECM molecules. On the other hand, EMMPRIN protein and MMP-9 mRNA expression were induced in BRL3A cells. The increase in EMMPRIN expression in BRL3A cells was inhibited by an anti-EMMPRIN antibody. These results reinforce the main role of EMMPRIN mediating tumor-host interactions that may evolve new opportunities for therapeutic interventions.

Evaluation of telomerase in the development and progression of colon cancer.

Telomerase activity, a cardinal requirement for immortalization, is a crucial step in the development of cancer and has been studied in many kinds of malignant tumours for clinical diagnostic and/or prognostic utilities. Using a PCR-based TRAP assay, we investigated telomerase activity in 8 adenomatous polyps, 9 dysplastic polyps, and in 36 paired cancer-normal mucosa specimens, one liver and one spleen metastasis from patients resected for sporadic colorectal cancer. Telomerase was absent or very low in normal mucosa and in adenomatous polyps. Dysplastic polyps and adenocarcinoma samples showed telomerase activity, with higher levels in cancer tissues compared to dysplastic lesions. A high telomerase activity was shown to be associated with late-staged cancers and metastasis, providing arguments supporting the role of telomerase not only in the development but also in the progression of colorectal carcinoma. Moreover, telomerase evaluation may help to confirm the malignant transformation in polypoid colorectal lesions with different levels of dysplastic alterations.

Activating mutations in the catalytic or juxtamembrane domain of c-kit in splenic mast cell tumors of cats.

OBJECTIVE: To evaluate splenic mast cell tumors (MCT) of cats for activating mutations in the proto-oncogene c-kit. SAMPLE POPULATION: 10 formalin-fixed, paraffin-embedded splenic MCT from cats in the pathology database of the Veterinary Medical Teaching Hospital at the University of California, Davis. PROCEDURE: Genomic DNA was isolated from tumor specimens, and the polymerase chain reaction (PCR) procedure was performed for exons 11, 12, and 17. The PCR products were analyzed by use of agarose gel electrophoresis and then directly sequenced. RESULTS: We did not identify mutations in the juxtamembrane domain (encoded by exons 11 and 12) or catalytic domain (encoded by exon 17) of c-kit in any of the splenic MCT specimens. CONCLUSIONS AND CLINICAL RELEVANCE: Although mutations in the proto-oncogene c-kit occur frequently in naturally developing MCT in dogs and aggressive mastocytosis in humans, the data reported here documented that dysregulation of Kit function through activating mutations is unlikely in splenic MCT of cats. Therapeutic strategies aimed at inhibiting Kit signaling (ie, kinase inhibitors such as imatinib [STl571]) may not be of benefit for the treatment of this disease in cats.

Dysregulation of cyclin dependent kinase 6 expression in splenic marginal zone lymphoma through chromosome 7q translocations.

The increased or inappropriate expression of genes with oncogenic properties through specific chromosome translocations is an important event in the pathogenesis of B-cell lymphoproliferative diseases. Recent studies have found deletions or translocations of chromosome 7q to be the most common cytogenetic abnormality observed in SLVL, a leukemic variant of SMZL, with the q21-q22 region being most frequently affected. In three patients with translocations between chromosomes 2 and 7, the cloning of the breakpoints at 7q21 revealed that each was located within a small region of DNA 3.6 kb upstream of the transcription start site of cyclin dependent kinase 6 (CDK6). In each case the translocation event was consistent with aberrant VJ recombination between the immunoglobulin light chain region (Ig kappa) on chromosome 2p12 and DNA sequences at 7q21, resembling the heptamer recombination site. The t(7;21) breakpoint in an additional patient with splenic marginal zone lymphoma (SMZL), resided 66 kb telomeric to the t(2;7) breakpoints juxtaposing CDK6 to an uncharacterized transcript. In two of the SLVL patient samples, the CDK6 protein was found to be markedly over expressed. These results suggest that dysregulation of CDK6 gene expression contributes to the pathogenesis of SLVL and SMZL.

Remodeling of glycoconjugates on CD44 enhances cell adhesion to hyaluronate, tumor growth and metastasis in B16 melanoma cells expressing beta1,4-N-acetylglucosaminyltransferase III.

Beta1-4 N-acetylglucosaminyltransferase III (GnT-III) synthesizes bisecting N-acetylglucosamine structures on asparagine-linked oligosaccharides. Using B16-hm mouse melanoma cells stably expressing GnT-III activity as positive transfectants, the effect of bisecting N-acetylglucosamine on the function of CD44 was analyzed in association with adhesion to hyaluronate and tumor spread in mice. Transfection of GnT-III caused increased affinity of immunoprecipitated CD44 to erythro-agglutinating phytohemagglutinin, that preferentially recognizes bisecting N-acetylglucosamine, without affecting the surface CD44 amount, indicating an increase in bisecting N-acetylglucosamine residues on CD44 in positive transfectants. CD44-mediated adhesion to immobilized hyaluronate and the binding of fluorescence-labeled hyaluronate to the cell surface were increased in positive transfectants. The enhanced adhesion in positive transfectants was suppressed by the treatment with beta-N-acetylhexosaminidase, indicating that N-acetylglucosamine residues were responsible for the enhanced adhesion. Positive transfectants showed promoted CD44-mediated tumor growth and metastatic development in the spleen after subcutaneous inoculation into mice. These results indicate that glycosylation of CD44 due to GnT-III causes enhanced adhesion to hyaluronate, local tumor growth and metastatic growth in spleen, suggesting that the CD44-mediated adhesion and tumor spread can be modified through introduction of a glycosyltransferase gene.

Immunohistochemical demonstration of acid phosphatase isoenzyme 5 (tartrate-resistant) in paraffin sections of hairy cell leukemia and other hematologic disorders.

The demonstration of tartrate-resistant acid phosphatase (TRAP) activity has long been a cornerstone in the diagnosis of hairy cell leukemia (HCL). Recently a monoclonal antibody to this enzyme has been developed that can be used in an immunoperoxidase method on paraffin-embedded tissues. By using a peroxidase-labeled streptavidin biotin method, paraffin sections of B5 and formalin-fixed tissue from 86 cases of HCL (41 bone marrow, 36 spleen, 9 liver) were stained with the antibody to TRAP and compared against staining for CD20 (L26) and DBA.44 (DAKO, Carpinteria, Calif). In addition, 193 specimens (127 bone marrow, 42 lymph node, 19 spleen, 5 other) from a variety of neoplastic and nonneoplastic hematologic conditions were stained using the monoclonal antibody to TRAP. For comparison, these cases were also stained with DBA.44. In the cases of HCL, 80 of 86 specimens were immunoreactive for TRAP. While the antibody to TRAP generally stained less than 50% of the hairy cells, CD20 and DBA.44 stained 90% and 50% to 60% of hairy cells, respectively. Two of three cases of marginal zone lymphoma showed weak immunoreactivity to the TRAP antibody. Two specimens from a patient with Gaucher's disease and 8 of 13 cases of mastocytosis also showed positivity to the TRAP antibody in the macrophages and mast cells, respectively. In contrast, staining for DBA.44 was positive in 3 of 9 cases of B-cell large cell lymphoma, 1 of 4 cases of mantle cell lymphoma, and in the paraimmunoblasts of 1 of 7 cases of small lymphocytic lymphoma. Only HCL was TRAP and DBA.44 positive. This antibody to TRAP is a useful addition to the diagnosis of HCL but should be used in conjunction with CD20 and DBA.44. The use of this antibody to determine minimal residual disease after chemotherapy was not addressed.

Purification of DNA topoisomerase I from the spleen of a patient with non-Hodgkin's lymphoma.

DNA topoisomerase I (topo I) was purified 124-fold from the spleen of a patient which was diffusely infiltrated by malignant lymphoma. Extracts prepared from the lymphoma tissue demonstrated elevated topo I activity. The purification uses a new two step chromatographic method involving hydroxylapatite and Fast Protein Liquid Chromatography mono S. The purified enzyme has a molecular weight of 67 kilodaltons as determined by sodium dodecyl sulfate denaturing gel electrophoresis. Western blotting confirms the identity of the protein as topo I. The purified lymphoma topo I has a similar specific activity as topo I isolated by the same procedure from normal placenta. By using a new quantitative radiolabeled DNA relaxation assay, it was estimated that each molecule of topo I is able to relax 9.6 molecules of supercoiled DNA per min at 30C. In addition it was found that both the placental topo I and the lymphoma topo I were each 50% inhibited by 8 microns camptothecin and that the drug stimulates the lymphoma topo I to cleave supercoiled plasmid DNA. These findings indicate that the elevation of topo I measured in crude extracts of this human malignant lymphoma can be entirely accounted for by the increase in topo I protein in the tumor. Furthermore, the sensitivity of the lymphoma topo I towards camptothecin suggests that therapy with topo I directed agents might be beneficial in this tumor.

Establishment and characterization of a villous lymphoma cell line from splenic B-cell lymphoma.

A new B-cell line (VL51) with cytoplasmic villi was established from a female patient with splenic lymphoma with circulating villous lymphocytes (SLVL). The patient exhibited a clinical picture characteristic of SLVL, including massive enlargement of the spleen. Tartrate-resistant acid phosphatase (TRAP)-negative villous lymphocytes were seen in the peripheral blood, bone marrow (BM) and both red and white pulps of the spleen. Monoclonality of the VL51 cell line was confirmed by clonal genotype abnormalities in the immunoglobulin heavy chain (IgH) gene and the T-cell receptor beta (TCR beta) gene. Evidence for commitment of phenotype of the VL51 cell line to the B lineage was also shown by the immunophenotype, including expression of CD10, CD19, CD20 and surface immunoglobins. The VL51 cells were positive for Epstein-Barr virus nuclear antigen (EBNA). The VL51 cell line is the first SLVL cell line to be established, and it is expected to be useful in clarifying the leukemogenesis of SLVL.

Diffuse sinusoidal hemangiomatosis of the spleen. A case report with enzyme-histochemical, immunohistochemical, and electron-microscopic findings.

Diffuse hemangiomatosis of the spleen is a very rare benign tumor in which the whole spleen is permeated by neoplastic blood vessels. It is occasionally accompanied by severe disturbances of blood coagulation. The histogenesis of this tumor remains obscure. No systematic investigations of the immunophenotype of the neoplastic endothelium have been published. We describe a case of isolated benign diffuse hemangiomatosis of the spleen in which the enzyme-histochemical and immunohistochemical findings suggested an origin in the splenic sinus endothelial cells. Some of the tumor endothelial cells reacted with UEA-1, BMA 120, antibodies against the von Willebrand factor, CD34, and CD8, an antigen which, in man, is expressed only by suppressor/cytotoxic T cells and the endothelial cells of the splenic sinuses. Enzyme-histochemical investigations revealed reactivity for nonspecific esterase and lack of reactivity for alkaline phosphatase--a pattern typical of the sinus endothelial cells. The tumor could be distinguished from other tumors/tumor-like lesions of the spleen that exhibit endothelium with characteristics typical of the splenic sinuses (peliosis, splenoma, littoral cell angioma) on the basis of its histological features. The lack of expression of histiocytic antigens by the tumor endothelium is also evidence against a diagnosis of littoral cell angioma, which also derives from the sinus endothelium. Thus, this tumor could not be identified as any of the recognized tumors/tumor-like lesions of the spleen and it is therefore proposed that it should be designated diffuse sinusoidal hemangiomatosis.

Primary splenic lymphoma in a horse.

A well-demarcated solitary splenic mass (20 x 20 x 15 cm in size) containing hemorrhagic and necrotic foci was observed in a 4-year-old Thoroughbred stallion. Histologically, the mass consisted of lymphoma cells of the diffuse large non-cleaved type, with a high mitotic index and scattered macrophages that formed a starry sky pattern. The lymphoma cells revealed diffuse positivity for acid phosphatase and alpha naphthyl butyrate esterase, and were also positive for intracytoplasmic IgM on occasion, and mostly for proliferating cell nuclear antigen. Ultrastructural examination revealed moderately-developed rough endoplasmic reticulum sometimes with dilated cisternae. Thus, the diagnosis was a primary splenic lymphoma of B cell origin, but the exact reason for the absence of invasive growth or metastasis despite the high proliferative activity of this neoplasm was unclear.

Tartrate resistant acid phosphatase positive splenic lymphoma: a relatively benign condition occurring in a time-space cluster?

Conventional light and electron microscopic studies, together with cytochemical and immunocytochemical staining procedures, were carried out to ascertain whether the lymphomata of four elderly female patients living within 10 kilometers of each other, who presented within a short space of time with massive splenomegaly and varying cytopenia, belonged to any particular subgroup of lymphoma. In each case the lymphoma had a diffuse pattern and mature B cell phenotype. The malignant cells were of uniform cell type, slightly larger than admixed polymorphonuclear leucocytes, and showed minimal nuclear irregularity and positivity for tartrate resistant acid phosphatase (TRAP) staining. Their clinical and morphological features were compared with those of other lymphoproliferative disorders, but while sharing some features in common with each condition, this small group of patients seemed to have a unique combination of findings. The cytopenias of all four responded well after removal of the spleen and their disease has not been aggressive. It is concluded that these patients have a distinct subgroup of lymphoma, which it is important to recognise so that inappropriate use of aggressive cytotoxic drugs can be avoided.

Elevation of serum lactic dehydrogenase levels as an early marker of occult malignant lymphoma.

Elevated serum lactic dehydrogenase (LDH) levels, 595 to 615 microns/ml (normal less than 225 microns/ml) with predominance of LDH isoenzymes 2 and 3 was the early and only sign of occult malignant lymphoma in three patients. In the first patient, overt lymphoma appeared clinically only 2 months after the finding of elevated serum LDH levels, whereas in the other two asymptomatic patients, pathologic LDH levels were the only clues to the need for further diagnostic investigation. It is concluded that LDH may have a diagnostic value in the preclinical stage of malignant lymphoma. Thus, a patient with no apparent cause for elevated serum LDH levels warrants a thorough work-up including abdominal CT scan and even explorative laparotomy.

Histiocytic malignancies. Morphologic, immunologic, and enzymatic heterogeneity.

We have studied 14 hematopoietic malignancies with histologic features of histiocytic differentiation, using frozen section immunologic stains, plastic section enzyme histochemistry, and paraffin section immunocytochemistry. There was morphologic, immunologic, and enzymatic heterogeneity, including findings in seven cases that suggested differentiation toward specialized subsets of histiocytes. Four cases expressed a mature monocyte/macrophage phenotype by frozen section monoclonal antibody staining and three of these had histologic patterns diagnostic of malignant histiocytosis; two other cases had ATPase and S100 protein reactivity and morphologic features consistent with interdigitating (reticulum) cell proliferations; and one case was alkaline phosphatase positive, suggestive of differentiation toward fibroblastic reticulum cells. Four cases had histologic findings consistent with malignant histiocytosis, but weak or unreactive staining patterns and were considered poorly differentiated histiocytic or primitive hematopoietic malignancies. Three other cases, also morphologically consistent with malignant histiocytosis, were identified as probably T-cell lymphomas. The morphologic and phenotypic characteristics of non-neoplastic histiocytes and dendritic cell types and their related neoplasms are discussed. Histiocytic malignancies comprise a diverse group that can be identified and subclassified by immunologic and enzymatic techniques.

[Modification of splenic 5'-nucleotidase activity during proliferative processes in the spleen. Histoenzymatic study in the rat]. / Modification de l'activité 5'nucléotidasique splénique au cours de processus prolifératifs siégeant dans la rate. Etude histoenzymatique chez le rat.

In the rat spleen, periarteriolar lymphocyte sheath and the external area of the germinal center in the white pulp and the Billroth's cords in the red pulp possess a strong 5'Nucleotidase activity. During antigenic stimulation a lymphocyte proliferation occurs in the white pulp, while 5'Nucleotidase activity is weak. In the germinal center there is inverse relationship between development of the mitotic internal area and the 5'Nucleotidase external zone. Likewise in the myeloid metaplasia of the red pulp induced by fibrosarcoma development, the 5'Nucleotidase of the Billroth's cords is decreased. 5'Nucleotidase might exert a negative control on cell proliferation probably through adenosine production. On the other hand this enzymatic activity might gave back available nucleosides for cellular proliferation, lymphocytes being especially impermeable to nucleotides.