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TEM8 interacts with the cleaved C5 domain of collagen alpha 3(VI).

Tumor endothelial marker (TEM)8 was uncovered as a gene expressed predominantly in tumor endothelium, and its protein product was recently identified as the receptor for anthrax toxin. Here, we demonstrate that TEM8 protein is preferentially expressed in endothelial cells of neoplastic tissue. We used the extracellular domain of TEM8 to search for ligands and identified the alpha 3 subunit of collagen VI as an interacting partner. The TEM8-interacting region on collagen alpha 3(VI) was mapped to its COOH-terminal C5 domain. Remarkably, collagen alpha 3(VI) is also preferentially expressed in tumor endothelium in a pattern concordant with that of TEM8. These results suggest that the TEM8/C5 interaction may play an important biological role in tumor angiogenesis.

Collagen Type VI↗

The CXCR5 chemokine receptor is expressed by carcinoma cells and promotes growth of colon carcinoma in the liver.

The chemokine receptor CXCR5 is expressed by B cells and certain T cells and controls their migration into and within lymph nodes. Its ligand BCA-1/CXCL13 is present in lymph nodes and spleen and also in the liver. Surprisingly, we detected CXCR5 in several mouse and human carcinoma cell lines. CXCR5 was particularly prominent in pancreatic carcinoma cell lines and was also detected by immunohistochemistry in 7 of 18 human pancreatic carcinoma tissues. Expression in CT26 colon carcinoma was low in vitro, up-regulated in vivo, and rapidly lost when cells were explanted in vitro. CXCL13 strongly promoted proliferation of CXCR5-transfected CT26 cells in vitro. In the liver, after intrasplenic injection, these CXCR5 transfectants initially grew faster than controls, but the growth rate of control tumors accelerated later to become similar to the transfectants, likely due to the up-regulation of CXCR5. Inhibition of CXCR5 function, by trapping CXCR5 in the endoplasmic reticulum using a CXCL13-KDEL "intrakine," had no effect on initial growth of liver foci but later caused a prolonged growth arrest. In contrast, s.c. and lung tumors of CXCR5- and intrakine-transfected cells grew at similar rates as controls. We conclude that expression of CXCR5 on tumor cells promotes the growth of tumor cells in the liver and, at least for CT26 cells, seems to be required for outgrowth to large liver tumors. Given the limited expression on normal cells, CXCR5 may constitute an attractive target for therapy, particularly for pancreatic carcinoma.

Adenocarcinoma↗

Expression of DNA mismatch repair proteins hMSH2 and hMLH1 and the cyclin G1 inhibitor, p21(waf1/cip1) in pediatric tumors: correlation with response to therapy.

The expression of the DNA mismatch repair proteins hMSH2 and hMLH1 and p21(waf1) the cyclin G1 inhibitor, may determine response of adult cancers to anti-cancer drugs, that include alkylating agents and platinum-based drugs. The role of DNA mismatch repair proteins (hMSH2 and hMLH1) and p21(waf1) in pediatric tumor responses to chemotherapy and irradiation is described in the present study of 23 pediatric solid cancers (4 wilms' tumors, 9 neuroblastomas, 3 hepatoblastomas, 3 lymphomas and 4 sarcomas) using immunohistochemical methods. Immunostaining was scored for intensity (0-3) and extent (0-3). Most tumors stained strongly for hMSH2 and weakly or negative for hMLH1. All the hMLH1 negative tumors (1 wilms', 1 hepatoblastoma, 1 sarcoma, 2 lymphomas and 2 neuroblastomas) achieved complete response. p21(waf1) negative and positive tumors achieved relatively similar treatment response. The results suggest that the expression of DNA mismatch repair proteins hMLH1 and hMSH2, and p21(waf1) do not influence individual cancer responses to treatment and the results may reflect the use of multiple drugs and irradiation that cause many different types of DNA damage.

Adaptor Proteins, Signal Transducing↗

[Detection of API2-MALT1 fusion gene in extranodal B-cell lymphoma and its significance].

OBJECTIVE: To study the expression of API2-MALT1 mRNA in mucosa-associated lymphoid tissue (MALT) lymphoma, extranodal diffuse large B-cell lymphoma (DLBCL) and Hashimoto's thyroiditis, to investigate the expression pattern of API2-MALT1 variants, and to correlate the findings with the clinicopathologic features and prognosis. METHODS: Sixty-two cases of MALT lymphoma (10 from lung, 31 from stomach, 9 from intestine and 12 from thyroid), 32 cases of extranodal DLBCL (16 from stomach, 13 from intestine and 3 from thyroid), 8 cases of Hashimoto's thyroiditis and 5 cases of reactive lymph nodes hyperplasia as negative controls were collected. The expression of API2-MALT1 mRNA was studied in all cases by reverse transcriptase (RT)-polymerase chain reaction (PCR) and nested PCR. The 94 cases of lymphoma were subdivided into API2-MALT1-positive and API2-MALT1-negative groups. Among the patients, 78 were followed up for 6 to 120 months. The differences in clinicopathologic features and prognosis between the two groups were analyzed. RESULTS: API2-MALT1 transcripts were detected in 39 of the 94 lymphoma cases (with 28 cases being MALT lymphoma and 11 cases being extranodal DLBCL). mRNA expression was not detected in all cases of Hashimoto's thyroiditis and the negative controls. Two fusion gene variants, A1446-M1123 and A1446-M814 were found, and A1446-M1123 expression was more common. As for MALT lymphoma cases, the frequency of the fusion gene expression was lower in thyroid, when compared with that in lung, stomach and intestine. API2-MALT1-positive cases had tumors in an earlier stage with milder infiltration of cancer cells, lower relapse rate, and higher five-year survival rate. CONCLUSIONS: The expression of API2-MALT1 mRNA can be detected in both MALT lymphoma and extranodal DLBCL, but not in Hashimoto's thyroiditis. These cases tend to show a more indolent clinical course and better survival. The frequency of t (11; 18) (q21; q21) correlates with the primary sites of MALT lymphoma. The higher incidence of breakpoint at 1123 bp of MALT1 gene in Chinese people may be due to geographical variation.

Caspases↗

Interaction of an estramustine photoaffinity analogue with cytoskeletal proteins in prostate carcinoma cells.

To identify specific drug targets of the antimitotic drug estramustine, a photoaffinity analogue, 17-O-[[2-[3-(4-azido-3-[125I] iodophenyl)propionamido]ethyl]carbamyl]estradiol-3-N-bis(2- chloroethyl)carbamate, was synthesized and reacted in competition assays with cytoskeletal protein preparations. By attaching the photoaffinity ligand to the 17 beta-position of the steroid D-ring, the cytotoxic properties of the drug were maintained. In cytoskeletal protein preparations from human prostate carcinoma cells (DU 145) or a clonally selected, estramustine-resistant cell line (E4), the major microtubule-associated protein (MAP) present was MAP4. In both cytoskeletal fractions and reconstituted microtubules, 17-O-[[2-[3-(4-azido-3-[125I]iodophenyl)propionamido] ethyl]carbamyl]estradiol-3-N-bis(2-chloroethyl)carbamate bound to both MAP4 and tubulin. From competition assays, the apparent binding constant for MAP4 from DU 145 cells was 15 microM. Similar calculations for tubulin gave values of 13 microM (bovine brain), 19 microM (DU 145 wild-type cells), and 25 microM (E4 cells). The identification of these cytoskeletal proteins as specific drug targets provides a direct explanation for the antimicrotubule and antimitotic effects of estramustine.

Affinity Labels↗

Caprine peripheral neuroblastomas: structural and ultrastructural features, intermediate filaments profile and neuro-endocrine characterization.

In this report the morphological and immunohistochemical features with respect to intermediate filament proteins and the neuroendocrine nature of bilateral neuroblastomas possibly originating from the adrenal medulla in a goat kid are presented. Histologically, the tumours were composed of small, round, blue cells organized in highly cellular nests and sheets separated by fibrovascular septa. Isolated cells mimicking the morphological features of neurones were observed in both tumours. Ultrastructurally, dense-core neurosecretory granules, about 100 nm in diameter, and irregularly organized neurotubular networks were seen. The small tumour cells were only labelled by vimentin, while the neurone-like cells were labelled by both neurone-specific enolase and synaptophysin. The lack of staining of the tumour cells by the neurofilament proteins antiserum, which was also observed in a human neuroblastoma (used as positive control) has been previously reported and is probably the result of the tissue processing and/or the poor differentiation stage of the tumours. The vimentin labelling of tumour cells could be explained by the poor differentiation stage of the tumours, since vimentin is the only intermediate filament protein in presumptive neuroblasts, being replaced by neurofilament proteins in later stages of neurogenesis.

Animals↗

[Nephrogenic adenoma of the bladder. Morphological and immunophenotypic study with particular attention to differential diagnosis].

BACKGROUND: Nephrogenic Adenoma (NA) is a rare lesion of the urinary tract, considered a metaplastic response to chronic inflammation, trauma or immunosuppression. METHODS AND RESULTS: We report two cases of NA arising in the urinary bladder of patients with previous history of recurrent urinary tract infections due to neuropsychiatric disease. Pathological examination of the lesions, resected by transurethral (TUR) management, revealed a papillary proliferation of tubules and cysts lined by cuboidal to low-columnar cells without atypia. Immunohistochemistry showed positivity for Cam 5.2, CK7 and EMA. MIB 1 count demonstrated a positivity in 12/200 cells in case 1 and < 2/200 in case 2. No expression of nuclear p53 was evident. CONCLUSION: NA is a benign unusual neoplasm which might be misdiagnosed as clear cell adenocarcinoma of the bladder or prostatic adenocarcinoma. Its recognition is important because it is a benign lesion cured by a conservative resection and no additional therapy is generally required.

Adenocarcinoma↗

Mismatch repair gene expression and genetic instability in testicular germ cell tumor.

Human mismatch repair (MMR) genes encode highly conserved interacting proteins that correct replication errors predisposing to hereditary gastrointestinal and genitourinary malignancies. A subset of sporadic genitourinary tumors also exhibits MMR deficiency and can be identified by measuring the frequency of microsatellite instability (MSI) in cancer cell DNA. We investigated expression of the two most commonly mutated MMR genes, MSH2 and MLH1, in sporadic testicular germ cell tumor (GCT) in order to: (1) determine the expression pattern of MSH2 and MLH1 proteins in normal seminiferous tubules and histologically distinct GCT subtypes, (2) correlate MMR gene expression with genetic instability in GCT and (3) develop a panel of molecular markers that can identify genetically distinct subsets of GCT for prognostic assessment. MSH2 and MLH1 had differential staining patterns in normal seminiferous tubules and malignant tissues. MSH2 was expressed in all stages of spermatogenesis up to but excluding mature sperm whereas MLH1 was predominantly expressed in premeiotic germ cells. All histological GCT subtypes showed differential immunostaining for MSH2 and MLH1 however pure seminoma had statistically significant fewer low MSH2 staining tumors than other subtypes (p = 0.046). Twenty-five percent of GCT exhibited increased frequency of MSI (MSI+ tumors) with 73, 70 and 43% of MSI+ tumors exhibiting low MSH2, low MLH1 or low MSH2 and low MLH1 staining respectively. Fifteen percent of testicular GCT exhibited loss of heterozygosity (LOH) but no MSI (LOH only tumors). Only 28, 17 or 6% of LOH only tumors exhibited low MSH2, low MLH1 or low MSH2 and low MLH1 staining respectively.

Adaptor Proteins, Signal Transducing↗

Quantification of expression of netrins, slits and their receptors in human prostate tumors.

Recently, DCC (Deleted in Colorectal Cancer) protein has been forwarded as a receptor for netrin. The Netrin/DCC complex is critical for axon guidance and cell migration. In the developing nervous system, netrin protein secreted by midline cells attracts commissural axons by activating the DCC receptor on growth cones. This attraction can be switched to repulsion or silenced completely, depending on the DCC binding partner. The potential suppressor function of DCC in prostate tumorigenesis, through a still unknown mechanism, prompted us to quantify the expression of several genes involved in this axon guidance pathway. The relative expression levels of DCC, NEO1, NTN1, NTN2L, NTN4, UNC5C, Slit1, Slit2, Slit3, Robo1 and Robo2 were simultaneous quantified in 48 tumors and 7 normal prostate tissues by using real-time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). A reduction in DCC, NEO1, NTN1 and NTN4 expression was observed in prostate tumors, while many of the same prostate tumors over-expressed either Slit genes or their receptors, Robo.

Adenocarcinoma↗

The use of two-dimensional gel electrophoresis in studies on the role of cytoskeletal plaque proteins as tumor suppressors.

The morphology and functions of cells and tissues are determined, in a large part, by mechanical forces generated at cell-cell and cell-extracellular matrix (ECM) contacts. At these sites, transmembrane adhesion receptors of the integrin and cadherin families are linked, via their cytoplasmic domain, to the cytoskeleton by submembranal plaque proteins such as vinculin, alpha-actinin and the cell-cell junctional plaque proteins alpha- and beta-catenin and plakoglobin (or gamma-catenin). Recent studies have implicated this link of structural molecules between the outside and inside of the cell in signal transduction. We have shown that the expression of junctional plaque proteins is modulated during growth stimulation and differentiation, and is dramatically reduced in certain tumor cells. To study the functional significance of these changes in expression, we have used recombinant DNA technologies to overexpress or suppress the levels of junctional plaque proteins. In addition, we eliminated the expression of vinculin in embryonal stem (ES) cells and in the embryonal carcinoma F9 line by gene disruption employing homologous recombination. The results have indicated that moderate overexpression of cell-ECM plaque proteins results in reduced cell motility. In contrast, suppression of their expression, by antisense transfection, led to enhanced motility and conferred anchorage independent growth and tumorigenicity, upon injection into nude mice. These findings suggest that submembranal plaque proteins can act as effective tumor suppressors. In agreement with this notion, we found in several tumor cell lines diminished levels of junctional plaque proteins. Restoration of their level to that found in normal cells resulted in tumor suppression after their injection into experimental animals. Here we demonstrate the usefulness of the application of two dimensional (2-D) gel electrophoresis in these studies.

Actinin↗