Interferon alpha induction of Stat1 and Stat2 and their prognostic significance in carcinoid tumors.

IFN-alpha has been shown to elicit antitumor activity in carcinoid tumors. In the present study the effects of IFN-alpha on the protein expression involved in the IFN-alpha signaling, which were recognized as signal transducer and activators of transcription (Stats), were investigated. Archive specimens from 45 carcinoid patients, 33 before IFN-alpha and 45 during treatment, were studied. The tissues were immunostained for protein expression by using monoclonal anti-Stat1 and anti-Stat2 antibodies. Results showed that Stat1 and Stat2 immunostaining were significantly increased during IFN-alpha treatment. Stats scores were significantly increased only in patients with objective response as well as those with stable disease but not in those with progressive disease. The induction of Stats correlated with the survival rates of the patients. In addition, both Stat scores significantly correlated with the p68 protein expression. In a carcinoid tumor cell line, Bon1, IFN-alpha dose-dependently increased the Stat expression. Analysis of cell fractions showed that IFN-alpha increased Stat protein both in cytoplasm and nucleoplasm of the cells. Furthermore, IFN-alpha enhanced tyrosine phosphorylation of Stat1 and Stat2. Thus, the antitumor effect, in vivo and in vitro, in IFN-alpha-treated carcinoid tumors seems to be mediated via upregulation of Stat proteins and enhancement of phosphorylation of these proteins.

Differentially expressed cDNAs in PLCbeta3-induced tumor suppression in a human endocrine pancreatic tumor cell line: activation of the human mismatch repair protein 3 gene.

Phospholipase Cbeta3 (PLCB3) is located to chromosome 11q13 in the vicinity of the multiple endocrine neoplasia type1 (MEN1) gene and shows loss of expression in some neuroendocrine tumors. Transfection of PLCB3 to neuroendocrine cell lines induces growth suppression and phenotypic alterations, but the mechanisms remain unclear. To investigate the underlying events behind this tumor suppression, we performed an RT-Differential cDNA Display of total RNA from BON-1 (human endocrine pancreatic tumor cell line) transfected with PLCB3 and compared to wild type and BON-1 transfected with vector without insert. PLCB3 transfection resulted in increased expression of 4 genes and decreased of 2. The two inhibited were homologous to S100A3 and Chromogranin A. One of the four activated cDNAs could be identified as human mismatch repair protein 3 mRNA (hMSH3), and another was homologous to TIS/MA-3 mRNA (mouse topoisomerase suppressor inhibited gene/mouse apoptosis gene-3). Differential expression of these genes may contribute to the PLCB3-induced tumor suppression of neuroendocrine tumor cell lines.

The interferon-alpha regulation of interferon regulatory factor 1 (IRF-1) and IRF-2 has therapeutic implications in carcinoid tumors.

BACKGROUND: Interferon regulatory factor 1 (IRF-1) has been demonstrated to possess antiproliferative and tumor suppressor functions, on the contrary. IRF-2 has been suggested to induce oncogenetic effect in some cell lines, but not evaluated in tumor patients. PATIENTS AND METHODS: In 35 carcinoid tumor patients, expressions of IRF-1 and IRF-2 were investigated by immunohistochemistry and their values were analyzed with clinical treatment response. In carcinoid tumor cell line, Bonl, effects of IFN-alpha on the expression of both IRF-1 and IRF-2 mRNAs and proteins were determined by Northern blot, RNase protection assays and Western blot analysis. RESULTS: IFN-alpha up-regulated the expression of IRF-1 and IRF-2 both in vivo and in vitro. In carcinoid tumors, IFN-alpha treatment led to a significant increase in the expression of IRF-1 (P < 0.001) and IRF-2 (P < 0.001). Moreover, the IRFs induction was correlated with the clinical response of IFN-alpha treatment, although their baseline values were not predictive. In addition, expressions of IRF-1 and IRF-2 were significantly correlated with the p68 kinase expression (P = 0.032 and P = 0.0176, respectively) and the expression of IRF-1 protein was positively correlated with that of IRF-2 (r = 0.671, P = 0.0001) tested in the same specimens. CONCLUSIONS: IRF-1 as well as IRF-2 have therapeutic implications in carcinoid tumors during treatment with interferon-alpha and IRFs induction might be used as indicators of response to treatment with interferon-alpha.

Subcellular distribution of phospholipase C isoforms in rodent pancreas and gastric mucosa.

Phosphoinositide-specific phospholipase C (PLC) has been implicated as a participant in cell proliferation as well as enzyme and hormone secretion. Defining the subcellular distribution of PLC isoforms would possibly contribute to further understanding of their function. We investigated the intracellular distribution of four PLCs (beta1, beta2, beta3, and gamma1) in mouse pancreatic cells as well as mouse and rat gastric mucosa cells by ultrastructural immunocytochemistry. In pancreatic acinar cells, PLCbeta1 and PLCgamma1 were demonstrated in the zymogen granules while PLCbeta2 was present in the granulae as well as the endoplasmic reticulum (ER), and PLCbeta3 was prominent in the ER. In the endocrine pancreas, PLCbeta2 immunolabeling was expressed in the secretory granulae of alpha, beta, delta, and pancreatic polypeptide cells. PLCbeta3 showed a slight labeling in the nucleus and ER of all four pancreatic endocrine cell types while PLCgamma1 was prominent in alpha cell granulae. In the gastric mucosa cells, PLCbeta2 was highly expressed in the heterochromatin areas and in the ER of parietal, chief, mucous, and enterochromaffin-like cells. PLCbeta3 were expressed in a manner similar to PLCbeta2 in those cells; however, no immunoreaction was seen in the ER of parietal cell. PLCgamma1 was demonstrated in the chief cell granulae. One possible, although yet speculative, interpretation of our results is that the studied PLC isoforms may be involved in processing in pancreatic secretory granulae and that nuclear PLCbeta2 and PLCbeta3 signaling pathways may be operative in the cells of the gastric mucosa.

Expression of lactoferrin in the kidney: implications for innate immunity and iron metabolism.

BACKGROUND: Sequestering of free iron by lactoferrin (LF) is important in the defense against bacteria. In a screening for LF expression in various organs, high levels of LF mRNA were detected in human kidney. This indicated that LF is produced by the kidney and that it may participate in innate immunity of this organ. METHODS AND RESULTS: Antibody staining and in situ hybridization of paraffin-embedded kidney sections showed that LF is expressed in cells lining the distal collecting ducts of the medulla. High levels of both protein and mRNA were detected in these cells. However, a clear difference in the distribution of mRNA and protein within the tissue was observed. LF mRNA was detected along a relatively large portion of the tubuli, whereas LF antigen was found mainly in the very distal regions of the same tubuli. This indicates that LF is released by large regions of the tubuli and possibly reabsorbed in the most distal parts. Using enzyme-linked immunosorbent assay, only very low LF levels were detected in urine. CONCLUSION: The present study shows that LF is produced by the kidney and that both LF mRNA and protein are distributed in a highly ordered fashion. This latter finding, together with the very low levels of LF detected in urine, indicates that LF may contribute to the immune defense in the kidney by reduction of available free iron in the urine. Other possibilities are that LF may play a role in the iron metabolism by recovering free iron from urine and making it available for metabolic use, and that LF may participate in the antioxidant defense systems protecting the kidney against nonmicrobial oxidative injury, that is, ischemia, reperfusion and inflammation.

Transmembrane protein tyrosine phosphatase IA-2 (ICA512) is expressed in human midgut carcinoids but is not detectable in normal enterochromaffin cells.

A potential upregulation of receptor type protein tyrosine phosphatase IA-2 (ICA512) expression was detected by differential display and investigated in midgut carcinoid tumours. Normal intestine tissue and tumour tissue from 13 midgut carcinoid patients were studied by in situ hybridisation using an IA-2 ribonucleotide probe and confocal microscopy using specific IA-2 antibodies. Previously, it had been shown that IA-2 is located in the secretory granules of virtually all neuroendocrine cells. However, we found that IA-2 was not detectable in resting normal enterochromaffin (EC) cells of the small intestine, while high expression of IA-2 mRNA and protein was confirmed in both primary and metastatic carcinoid tissue. This difference in expression was not observed with chromogranin A or serotonin, two secretory granule hormones known to be expressed in EC cells, indicating that IA-2 was seemingly not necessary for the basal production and packaging of these hormones. When comparing patients receiving biotherapy before operation with untreated patients, we found expression of IA-2 to be lower in tumours from patients that had been treated with a combination of alpha-interferon and the somatostatin analogue, octreotide. There was no correlation between IA-2 expression and proliferation rates as measured by immunohistochemistry with antibodies against the Ki 67 antigen. Furthermore, we show that IA-2 is co-localised with serotonin in carcinoid tumours as well as in the pancreatic tumour cell line, BON1, which is interesting as serotonin secretion rate is presumably higher in tumour cells than in resting EC cells. Taken together, these findings may indicate a role for IA-2 in the later stages of the regulated secretory process.

Menin represses JunD-activated transcription by a histone deacetylase-dependent mechanism.

Recently the multiple endocrine neoplasia type 1 (MEN-1) tumor suppressor gene was cloned. MEN-1 encodes a nuclear protein, called menin, of hitherto unknown function. In order to investigate the biological function of menin we employed the yeast two-hybrid system to identify menin-interacting proteins. Here we report that menin functions as a transcriptional repressor through interaction with the transcription factor JunD. The interaction is mediated via the N-terminal transcription activation domain of JunD, and the C-terminal part of menin. In transient co-transfection experiments, expression of menin leads to specific repression of JunD transcriptional activity, which is dependent on the integrity of the menin C-terminal region. C-Terminal truncations of the protein not only abolish repression, but increase JunD transcriptional activity, implying the existence of a functional domain separate from the JunD-binding region. Menin-mediated repression is relieved by the histone deacetylase inhibitor trichostatin A, indicating that deacetylation of histones is an essential component of this repression mechanism, as has recently been demonstrated for the retinoblastoma protein. Missense, in-frame deletions, frameshift and nonsense mutations lead to inactivation of menin or possibly to truncated proteins. This would result in loss of repression of menin/JunD target genes, as well as non-target genes through indirect mechanisms, deregulation of cellular growth control and endocrine tumorigenesis.

Suppression of the neoplastic phenotype by transfection of phospholipase C beta 3 to neuroendocrine tumor cells.

The expression of phospholipase C beta 3 (PLCB3) is low or absent in several neuroendocrine neoplasias. To investigate the role of PLCB3 in the neuroendocrine tumorigenesis, we transfected a PLCB3 construct to three neuroendocrine tumor cell lines with a low PLCB3 expression. The growth rate and tumorigenicity were assessed in vitro by [3H]thymidine incorporation and cell counting, in vivo, by xenografting to nude mice. In vitro, PLCB3 expressing clones showed a significant growth inhibition. The tumor weight was reduced for one of the two xenografted PLCB3-transfected cell lines and in both, a reduced number of proliferating (Ki-67 positive) cells was observed. This study implies an essential role for PLCB3 in the neuroendocrine tumorigenesis.

Inhibition of CDK2, CDK4 and cyclin E and increased expression of p27Kip1 during treatment with interferon-alpha in carcinoid tumor cells.

IFN-alpha has presented antitumor effect in about 50% of carcinoid tumor patients, though the antitumor mechanism of IFN-alpha is still to be elucidated. In this study we demonstrated that IFN-alpha could result in accumulation of S-phase population and upregulation of cyclin-dependent kinase inhibitor (CKI), p27. Moreover, IFN-alpha inhibits DNA synthesis assessed by [3H] thymidine incorporation and colony formation on soft agar. Immunodepletion of p27 increased CDK2- and cyclin E-associated kinase activities. These data suggest that IFN-alpha exerts its antiproliferative effects in the neuroendocrine differentiated cell lines by: 1) inhibition of DNA synthesis and colony formation, 2) upregulation on the mRNA and protein expressions of the CKI, p27.

Determination of somatostatin receptor subtype 2 in carcinoid tumors by immunohistochemical investigation with somatostatin receptor subtype 2 antibodies.

We have shown previously that expression of mRNA for somatostatin receptor subtype 2 (sst2) detected by in situ hybridization correlates to therapeutic outcome in patients with carcinoid tumors treated with somatostatin analogues. However, in situ hybridization is laborious and not practical in clinical routine work. We have, therefore, developed polyclonal antibodies directed against sst2 that may be used for immunohistochemistry on tissue specimens. The staining is specific and is highly correlated to expression of mRNA for sst2 (P < 0.01) as well as to tracer uptake at somatostatin receptor scintigraphy (P < 0.01). There is also a good correlation to the therapeutic response in carcinoid patients treated with somatostatin analogues (P < 0.05). Of 35 patients with carcinoid tumors included in this investigation, 25 stained positive with the antibodies. Twenty-two of these were investigated by somatostatin receptor scintigraphy and showed tracer uptake in metastases. An additional two patients that did not stain with the antibodies showed pathological uptake of the tracer in metastases, which might indicate binding to somatostatin receptor subtype 5. None of the 10 patients without positive immunostaining responded to somatostatin analogue treatment, whereas patients with a positive stain had a biochemical response or remained stable during treatment. Thus, these antibodies may be used to determine the presence of sst2 in carcinoid tumors and to select patients suitable for somatostatin analogue treatment. The method is easily applicable in clinical practice.

Expression of p68 protein kinase and its prognostic significance during IFN-alpha therapy in patients with carcinoid tumours.

The aim of this study was to evaluate the antiproliferative effects of interferon alpha (IFN-alpha) on neuroendocrine differentiated cell lines and, retrospectively, to assess the prognostic significance of p68 protein kinase (PKR) induction in neuroendocrine gut and pancreatic tumour patients. Archive specimens from 56 patients were studied, 43 before IFN-alpha and 56 during therapy. The tissues were immunostained for p68 protein kinase (PKR) using the monoclonal antibody (MAb) TJ4C4. A significant increase in immunostaining after treatment with IFN-alpha compared with before treatment (3.47 +/- 0.12 versus 2.72 +/- 0.15, P < 0.001) was noted. The p68 score was significantly increased after treatment only in patients with stable disease before = 2.71 +/- 0.19, after = 3.40 +/- 0.14 (P < 0.001) or an objective response before 3.13 +/- 0.22, after = 4.00 +/- 0.24 (P < 0.05) but not in those with progressive disease (before = 2.32 +/- 0.24, after 2.86 +/- 0.26, NS). A low p68 score (< 3.0) during treatment was a predictor of shorter duration of response and overall survival (P = 0.0062 and P < 0.0001, respectively). Furthermore, IFN-alpha showed a significant antiproliferative effect (by [3H]thymidine incorporation) on two carcinoid tumour cell lines in a dose-dependent manner which correlated with a dose-dependent induction of p68 mRNA and protein expression (by Northern and Western blot analysis). We conclude that IFN-alpha can effectively inhibit the in vitro growth of carcinoid tumor cell lines and upregulates the expression of p68 at both mRNA and protein levels in carcinoid tumours. The induction of p68 could be a prognostic indicator of response in patients with carcinoid tumours during IFN-alpha treatment.

Interferon-alpha induces bcl-2 proto-oncogene in patients with neuroendocrine gut tumor responding to its antitumor action.

We have studied the expression of apoptosis regulating genes bcl-2 and bax in neuroendocrine gut tumors. The expression pattern of these genes was compared with the clinical response (changes in the tumor markers and changes of the tumor size determined by radiology) after treatment with interferon-alpha (IFN-alpha, n = 13), somatostatin analog (octreotide, n = 3; lanreotide, n = 2) or a combination of both (n = 5). Immunohistochemistry and in situ RT-PCR were performed and expressions were scored from 0 (no staining) to 6 (strong and wide-spread staining). With regard to clinical outcome, the scores (mean +/- SEM) of immunohistochemical staining of bcl-2 and bax were 1.77 +/- 0.25 and 4 +/- 0.22 for patients with stable disease and, 0.54 +/- 0.28 and 4.68 +/- 0.21 for patients with progressive disease. The scores of bcl-2 and bax staining for IFN-alpha-treated patients were 1.96 +/- 0.35 and 4.12 +/- 0.31 and for untreated patients were 0.5 +/- 0.25 and 4.5 +/- 0.21, respectively. Expression of bcl-2 was observed in all IFN-alpha-treated patients who responded to the drug but not in nonresponsive patients (p = 0.0027). In contrast, bax, a promotor of apoptosis was expressed in all patients with higher degree of expression seen in patients with progressive disease (p = 0.0364). We have also detected bcl-2 expression by western blot analysis in neuroendocrine tumor tissue grown in nude mice, which were treated with IFN-alpha for 28 days. Our results indicate that, IFN-alpha can induce bcl-2. Thus, we, propose that bcl-2 may be used as a prognostic marker for IFN-alpha sensitivity of neuroendocrine tumors.

A comparison between the efficacy of somatostatin receptor scintigraphy and that of in situ hybridization for somatostatin receptor subtype 2 messenger RNA to predict therapeutic outcome in carcinoid patients.

Predictive tests for treatment with somatostatin analogues have been asked for by clinicians. We have shown previously that somatostatin receptor (sstr) scintigraphy may be used to predict therapeutic outcomes for carcinoid patients receiving somatostatin analogues. However, almost 20% of patients with pathological tracer uptake fail to respond to such treatment. To increase further the reliability and prognostic value of sstr identification, we investigated the presence of mRNA for the subtypes sstr1 and sstr2 by in situ hybridization on tumor specimen from 25 carcinoid patients (22 midgut, 2 foregut, and 1 hindgut), all receiving somatostatin analogue treatment (12 lanreotide, 8 octreotide, and 5 octastatin) and compared this to the therapeutic response evaluated as inhibition of hormone secretion. Expression of sstr2 mRNA could be detected in 15 patients, all responding to somatostatin analogue treatment and showing pathological tracer uptake in tumor lesions at sstr scintigraphy. In the remaining 10 patients, no sstr2 mRNA could be detected, and none of the patients responded to somatostatin analogue treatment. Three of these 10 patients failed to accumulate tracer activity at sstr scintigraphy, whereas 7 had a pathological uptake of [(111)In-DTPA-D-Phe(1)]-octreotide. We conclude that in this group of carcinoid patients, there was complete agreement between the presence of mRNA for sstr2 detected by in situ hybridization and therapeutic outcome. In patients with pathological tracer accumulation without expression of somatostatin sstr2 mRNA, other sstr may be present that can bind the somatostatin analogue but not inhibit hormone secretion.

Adrenal lesion in multiple endocrine neoplasia type 1.

BACKGROUND: Multiple endocrine neoplasia (MEN) type 1 is accompanied by adrenal involvement, but characteristics and clinical handling of this lesion have been insufficiently explored. METHODS: Patients with MEN 1 (n = 43) were monitored (mean, 6.3 years) with annual biochemical and radiologic adrenal evaluation. Adrenal specimens were examined by in situ RNA-RNA hybridization for expression of the MEN1 candidate gene phospholipase C beta 3 (PLC beta 3) and immunostaining for insulin-like growth factor-1 receptor. RESULTS: Altogether 17 patients (40%) displayed adrenal enlargement, which was limited to the adrenal cortex and showed signs of progression, marked atypia, and cancer development in three of them. Only the carcinoma exhibited adrenocortical hormone excess. PLC beta 3 was expressed in the hyperplastic and adenomatous proliferation but not the carcinoma. Pancreatic endocrine tumors with insulin-proinsulin excess were overrepresented in the patients with adrenocortical involvement, but significant insulin-like growth factor-1 receptor immunoreactivity was restricted to the carcinoma. CONCLUSIONS: The prevalent adrenocortical lesion associated with MEN 1 requires regular attention because of malignant potential. It was unrelated to loss of constitution heterozygosity for the MEN1 locus (11q13) and PLC beta 3 expression, except for the cortical carcinoma exhibiting allelic losses involving also the Wiedemann-Beckwith gene at 11p15. Mechanisms for mitogenic relationships between the pancreatic and adrenal lesions of MEN 1 demand further clarification.

Hyperparathyroidism of multiple endocrine neoplasia type 1: candidate gene and parathyroid calcium sensing protein expression.

BACKGROUND: Hyperparathyroidism affects most patients with multiple endocrine neoplasia type 1 (MEN 1). This study investigates expression of the candidate MEN1 gene phospholipase C beta 3 (PLC beta 3) and expression and function of a putative calcium sensing protein (CAS) in hyperparathyroidism of MEN 1. METHODS: In 31 parathyroid glands from 17 patients with MEN 1, CAS distribution was studied immunohistochemically and parallel sections were explored for PLC beta 3 mRNA expression by in situ hybridization. Enzymatically dispersed parathyroid cells were analyzed for cytoplasmic calcium concentrations [Ca2+]i and parathyroid hormone (PTH) release. RESULTS: All glands exhibited a heterogeneously reduced CAS immunoreactivity, especially meager in nodularly assembled parathyroid cells. Calcium regulated [Ca2+]i and PTH release tended to be more deranged in the glands possessing the lowest immunostaining. Parathyroid PLC beta 3 invariably was homogeneously expressed, and this included even MEN 1 patients with reduced PLC beta 3 expression in endocrine pancreatic tumors. CONCLUSIONS: The findings support variable calcium insensitivity of [Ca2+]i and PTH release in hyperparathyroidism of MEN 1, apparently coupled to heterogeneously reduced CAS expression. For clarification of the role of PLC beta 3 in MEN 1 parathyroid tumorigenesis further study of this protein is required.

Candidate genes for multiple endocrine neoplasia type 1.

The aim of this study was to isolate and characterize candidates for the multiple endocrine neoplasia type 1 (MEN1) gene. The development of tumours related to MEN1 is associated with somatic deletions involving the MEN1 locus, suggesting inactivation of a tumour-suppressor gene in this region. We have isolated five cDNA candidates located within the 900 kb remaining for the MEN1 gene, determined their sequence, and characterized their expression in normal tissues and several endocrine tumours. One of the candidates, encoding for phospholipase C-beta 3, showed properties consistent with the idea of a tumour-suppressor gene.

Induction of MxA mRNA in patients with neuroendocrine tumors after interferon treatment. Lack of correlation with antitumor response.

We have investigated the possibility of using induction of MxA mRNA in patients with neuroendocrine tumors undergoing interferon-alpha(IFN-alpha) treatment as a predictive test for antitumor effect. A total of 122 patients with various types of neuroendocrine tumors were included in the study. Blood samples were drawn 12 hours after administration of either recombinant or natural IFN-alpha for analysis of induction of MxA mRNA in peripheral blood leukocyte (PBLs). Total RNA was isolated and slot-blot hybridization was performed using a MxA cDNA fragment as a probe. All patients displayed induction of MxA mRNA. Out of 13 untreated patients, 4 had MxA mRNA as well as 2 out of 11 patients treated with somatostatin analogue. All IFN-alpha treated patients showed induction of MxA mRNA and there was no difference between patients demonstrating partial remission, stable disease or progressive disease. Moreover, there was no difference between recombinant or natural leukocyte IFN-alpha in the ability to induce MxA mRNA. Six patients developed neutralizing IFN-alpha antibodies with 1 patient presenting a tire of 3200 NU/ml. Development of neutralizing antibodies did not abrogate the induction of MxA mRNA, but in 3 patients with high antibody titres the antitumor effect was lost. We therefore conclude that IFN-alpha is able to induce MxA mRNA in PBLs from patients with neuroendocrine tumors but we could not find any correlation with the therapeutic outcome. Furthermore, development of neutralizing IFN-alpha antibodies, although abrogating the antitumor effect, might not block the antiviral activity.

Expression and prognostic significance of TGF-beta isotypes, latent TGF-beta 1 binding protein, TGF-beta type I and type II receptors, and endoglin in normal ovary and ovarian neoplasms.

BACKGROUND: The etiology and biology of ovarian carcinogenesis is largely unknown. Recent results have indicated prognostic significance of growth factors in this malignancy. TGF-beta is a widely distributed growth factor with multifactorial effects in in vitro systems. Studies on the in vivo expression pattern of TGF-beta and its receptors might help us to understand its biologic significance in this malignancy. EXPERIMENTAL DESIGN: Tissue samples of normal ovary and benign as well as malignant ovarian neoplasms were examined for expression of transforming growth factor (TGF)-beta 1, -beta 2, and -beta 3, the latent TGF-beta-binding protein (LTBP), TGF-beta type I (T beta R-II) receptors and endoglin by immunohistochemistry and in situ hybridization. Furthermore, the results of the immunohistochemical analysis were compared with patient survival. RESULTS: Expression of all ligands was significantly increased in tumor cells compared with the normal epithelial cells. In contrast, LTBP immunoreactivity was detected significantly more often in normal epithelium than in tumor cells. T beta R-I and T beta R-II as well as endoglin were found in tumor tissues and normal ovary without any difference among the groups. In the blood vessels of malignant tumors, significantly increased TGF-beta 1 reactivity and decreased TGF-beta 2 reactivity were found when they were compared with those of normal ovaries and benign tumors. Patients with malignant tumors expressing TGF-beta 1, T beta R-I, or endoglin in blood vessels demonstrated longer survival than those having negatively stained tumors. In contrast, positive endoglin staining in tumor cells correlated with decreased survival even in advanced disease or in patients having residual tumor bulk after surgery. CONCLUSIONS: The differential expression of TGF-beta ligand and the significant correlations between expression of ligands or receptors and patient survival indicate involvement of the TGF-beta system in ovarian tumor development.

Assignment of the mouse homologue of a human MEN1 candidate gene, phospholipase C-beta 3 (Plcb3), to chromosome region 19B by FISH.

A recent study using comparative mapping analysis suggests that the proximal segment of mouse chromosome 19 contains the mouse homologs of the human multiple endocrine neoplasia type 1 (MEN1) flanking markers proximal to the locus. We have recently shown that phospholipase C-beta 3 (PLCB3) is a candidate gene for the MEN1 syndrome. In the present investigation we used fluorescence in situ hybridization with a genomic DNA clone for mouse Plcb3, and mapped the locus to chromosome region 19B. This is in agreement with the comparative mapping of the MEN1 flanking markers in mouse.

The phospholipase C beta 3 gene located in the MEN1 region shows loss of expression in endocrine tumours.

Oncogenesis of tumours related to multiple endocrine neoplasia type 1 (MEN1) is associated with somatic deletions involving the MEN1 locus, suggesting inactivation of a tumour suppressor gene in this region. Identification of meiotic cross-overs in MEN1 families has placed the MEN1 locus centromeric of D11S807. An extended deletion mapping was performed in 27 primary parathyroid tumours, and identified D11S427 as the closest centromeric flanking marker. Through physical mapping using newly isolated cDNA clones, we estimated the distance between the flanking markers D11S807 and D11S427 to be less than 900 kb. One of these cDNA clones showed expression of a 4.4 kb message in multiple tissues, including those affected in MEN1, while in five endocrine tumours no transcript was detected. Sequence characterization showed that this gene encodes for the phospholipase C beta 3, a key enzyme in signal transduction.