Inhibin/activin-betaE subunit is expressed in normal and pathological human placental tissue including chorionic carcinoma cell lines.

BACKGROUND: Inhibins and activins are important regulators of the female reproductive system. Recently, a novel inhibin subunit, named betaE, has been identified and shown to be expressed in several human tissues. However, only limited data on the expression of this novel inhibin-betaE subunit in normal and pathological human placenta as well as and human chorionic carcinoma cell lines exist. MATERIALS AND METHODS: Tissue specimens of normal, preeclamptic and HELLP pregnancies (n = 18) were obtained at the course of an cesarean section. Normal and pathological placental tissues as well as chorionic carcinoma cells (BeWo and JEG) were analyzed by using immunohistochemistry and RT-PCR. RESULTS: Expression of the inhibin betaE subunit could be demonstrated at the protein level by means of immunohistochemical evaluation and at the transcriptional level by betaE-specific RT-PCR analysis. The immunoreactive score for inhibin-betaE did not show any significant differences between normal, preeclamptic and HELLP tissue in extravillous trophoblast and syncytiotrophoblast cells. Expression of inhibin betaE could further be demonstrated for the human chorionic carcinoma cell lines JEG and BeWo. DISCUSSION: We demonstrated that inhibin-betaE is expressed in normal and pathological human placenta tissues. Although the precise role of this novel inhibin subunit for human placenta development is quite unclear, similarities with the well-characterized betaA- and betaB-subunits suggest an involvement in autocrine/paracrine signaling pathways, angiogenesis, decidualization and tissue remodeling under normal as well as malignant conditions. Additionally, the human chorionic carcinoma cell lines JEG and BeWo synthesize this subunit and therefore can be used as a cell culture model for further functional analysis of this subunit in human placental tissue.

Inhibin-betaC subunit expression in normal and pathological human placental tissues.

Inhibins and activins are important regulators of the female reproductive system. Recently, a novel inhibin betaC subunit has been identified. However, only limited data on the expression of this novel inhibin-betaC subunit in normal and pathological human placentas exist. Tissue specimens of normal, preeclamptic, hemolysis, elevated liver enzymes, low platelets (HELLP), and intrauterine growth restriction (IUGR) pregnancies (n=24) were obtained at the conclusion of a cesarean section. Normal and pathological placental tissues were analyzed by an immunohistochemical staining reaction with a specific antibody against this novel inhibin-betaC subunit. Overall, expression of the inhibin-betaC subunit could be demonstrated in normal and pathological placental tissue. The immunoreactive score (IRS) for inhibin-betaC did not show any significant differences between normal, preeclamptic, HELLP, and IUGR tissue in extravillous trophoblast and syncytiotrophoblast cells. Immunolabelling of this novel inhibin-ßC protein in normal and pathological placental tissue was demonstrated, although no differences in the staining intensity could be observed. Therefore, the inhibin-ßC isoform might not primarily be involved in the pathogenesis of these pregnancy-associated disorders. The functional role of this novel inhibin-betaC subunit in normal and pathological human placenta is still quite unclear and should thus be further investigated.

Inhibin/activin-betaC subunit in human endometrial adenocarcinomas and HEC-1a adenocarcinoma cell line.

INTRODUCTION: Inhibins and activins are important regulators of the female reproductive system. Recently, two novel inhibin subunits, named betaC (ßC) and betaE (ßE), have been identified. However, only limited data on the expression of the ßC subunit in human endometrioid adenocarcinomas exist. MATERIALS AND METHODS: Samples of uterine endometrioid adenocarcinomas were obtained and analysed by immunohistochemistry for the immunolabelling with an inhibin-ßC antibody. Additionally, the endometrial cancer cell line HEC-1a was used to assess the inhibin-betaC expression with the use of immunofluorescence. RESULTS: Expression of the inhibin-ßC subunit was demonstrated at the protein level by means of immunohistochemical evaluation in human endometrioid adenocarcinomas and the HEC-1a cell line. DISCUSSION: This study demonstrated, for the first time, that the novel inhibin/activin-ßC subunit is expressed in human endometrioid adenocarcinomas and in the human endometrial carcinoma cell line HEC-1a. Whether this novel ß-subunit has a substantial role in the pathogenesis and malignant transformation in human endometrium is still under investigation.

The metastasis-associated gene MTA3 is downregulated in advanced endometrioid adenocarcinomas.

The metastasis-associated gene MTA3 has an important function in invasion and metastasis of human cancer cells. Therefore, the aim of this study was to investigate the expression of this protein in endometrial adenocarcinomas and to analyse potential correlations between this nuclear transcription factor and estrogen receptors in endometrial adenocarcinomas. Additionally, we evaluated whether MTA3 might be a prognostic parameter in endometrioid adenocarcinomas. Endometrioid adenocarcinomas were obtained from 200 patients and immunohistochemically analysed for MTA3 and estrogen receptor alpha and beta (ER-alpha and ER-beta) expression. Overall, endometrioid adeno-carcinomas of histological differentiation grade 3 demonstrated a significantly lower expression of MTA3 compared to carcinomas of histological grade 1 and 2 (p<0.05). MTA3 expression is reduced in endometrioid adenocarcinomas of poor differentiation, though without any correlation to ER-alpha and ER-beta expression. Furthermore, the expression of MTA3 did not affect progression-free, cause-specific and overall survival. Overall, MTA3 did not constitute an independent prognostic factor in this study, suggesting that MTA3 is not a useful marker to assess and identify high-risk patients with endometrial adenocarcinomas. Still, the downregulation of MTA3 predispose this cell type to be of high metastatic potential after malignant transformation, playing an essential, but as yet unknown role in human endometrial carcinogenesis.

Immunohistochemical labeling of the inhibin/activin betaC subunit in normal human placental tissue and chorionic carcinoma cell lines.

Inhibins and activins are important regulators of the female reproductive system. A novel inhibin subunit, named betaC, has been identified and demonstrated to be expressed in several human tissues. We demonstrate here that inhibin betaC is expressed in human placenta. Expression of the inhibin betaC subunit was demonstrated at the protein level by means of immunohistochemical evaluation and at the transcriptional level by an inhibin betaC-specific RT-PCR analysis. Expression of inhibin betaC was detected in the human chorionic carcinoma cell lines JEG and BeWo. Although the precise role of this novel inhibin subunit in human placenta development and homeostasis is unclear, analogies with other inhibin subunits and the strong expression of betaC in normal human trophoblast cells and chorionic carcinoma cells suggest that betaC may be involved in autocrine/paracrine signaling pathways, angiogenesis, decidualization, and tissue remodeling under normal and malignant conditions. Additionally, JEG and BeWo express betaC and, therefore, can be used as a cell culture model for further functional analysis of this subunit in the human placenta.

Inhibin/activin-betaC and -betaE subunits in the Ishikawa human endometrial adenocarcinoma cell line.

BACKGROUND: Inhibins and activins are important regulators of the female reproductive system. Recently, two novel inhibin subunits, named betaC and betaE, have been identified and shown to be expressed in several human tissues. However, only limited data on the expression of these novel inhibin subunits in normal human endometrial tissue and endometrial adenocarcinoma cell lines exist. MATERIALS AND METHODS: Samples of proliferative and secretory human endometrium were obtained from five premenopausal, non-pregnant patients undergoing gynecological surgery for benign diseases. Normal endometrial tissue and Ishikawa endometrial adenocarcinoma cell lines were analyzed by immunohistochemistry, immunofluorescence and RT-PCR. RESULTS: Expression of the inhibin betaC and betaE subunits could be demonstrated at the protein level by means of immunohistochemical evaluation and at the transcriptional level by establishing a betaC- and betaE-specific RT-PCR analysis in normal human endometrial tissue and the parental Ishikawa cell line. Interestingly, in a highly de-differentiated subclone of the Ishikawa cell line lacking estrogen receptor expression, the expression of the inhibin-betaC subunit appeared strongly reduced. DISCUSSION: Here, we show for the first time that the novel inhibin/activin-betaC and -betaE subunits are expressed in normal human endometrium and the estrogen receptor positive human endometrial carcinoma cell line Ishikawa using RT-PCR and immunohistochemical detection methods. Interestingly, the Ishikawa minus cell line (lacking estrogen receptor expression) demonstrated no to minimal expression of the betaC subunit as observed with immunofluorescence and RT-PCR, suggesting a possible hormone- dependency of this subunit in human endometrial cancer cells. Moreover, because the Ishikawa cell line minus is thought to be a more malignant endometrial cell line than its estrogen receptor positive counterpart, inhibin-betaC subunit might be substantially involved in the pathogenesis and malignant transformation in human endometrium.

The metastasis-associated genes MTA1 and MTA3 are abundantly expressed in human placenta and chorionic carcinoma cells.

Normal placenta development relies on the ability of trophoblast cells to invade into the uterus and to build up an extensively vascularized feto-maternal tissue, necessary for the nutrition of the embryo. The ability of cell migration, invasion, and the ability to induce neovascularization are likewise hallmarks of cancer cells. The metastasis-associated genes MTA1 and MTA3 are known to be involved in cancer cell migration by regulation of cell adhesion proteins and to induce the expression of neoangiogenic cytokines, as recently shown by us for ovarian cancer cells. Therefore, we analyzed the expression of MTA1 and MTA3 in normal human placenta tissues and the chorionic cancer cell lines BeWo, JEG, and JAR. Immunohistochemical analysis revealed a rather strong expression of MTA1 and MTA3 in the nuclei of human trophoblast cells. A high expression level of MTA1 and MTA3 was further observed in the nuclei of human chorionic carcinoma cells, as shown by immunofluorescence analysis, and confirmed by Western blot and RT-PCR analysis. We conclude that the high expression level of MTA proteins in human chorionic cells might facilitate trophoblast cell migration and neoangiogenesis, and might further predispose human chorionic cancer cells with properties that are characteristic for this highly aggressive and metastatic carcinoma type.

Immunohistochemical labelling of steroid receptors in normal and malignant human endometrium.

For several years it was generally believed that only a single estrogen receptor (ER) and progesterone receptor (PR) existed. However, the discovery of a new ER (ERbeta) with specificity for estrogens has induced new insights in the estrogen signalling system. Moreover, PR is expressed as two major isoforms, PR-A and PR-B that arise from alternative transcriptional starting sites within the same gene. Although PR-A and PR-B were thought to occur in similar amounts, it is now clear that they are differentially expressed and thus have distinct functions in several human tissues, including human endometrium. The ER and PR expression and distribution pattern might play an important role in normal endometrial function and pathogenesis and the expression and relationship of the two distinct ER's and PR's could be of essential clinical implications. Moreover, the imbalance in ERalpha/ERbeta expression and the PR-A/PR-B ratio might play an important role in endometrial transition and subsequently influence endometrial pathogenesis. The knowledge of the pattern of steroid receptors in human endometrial tissue is of extreme importance, since it might start a new field in hormone therapy of endometrial cancer.

Development and characterisation of an antibody for the immunohistochemical detection of inhibin/activin betaE (betaE) in normal human ovarian and placental tissue.

Inhibin/activin subunits are homologues to each other and belong to the transforming growth factor-beta (TGF-beta) family of proteins. These proteins have been demonstrated to be disulphide-linked dimers, which have a common alpha-subunit but just one of two beta-subunits, differentiated in inhibin A (alpha-betaA) and in inhibin B (alpha-betaB). Recently, an additional beta-subunit has been identified, determined as betaE and being primarily synthesized in liver tissue. However, since no antibody against the betaE subunit is commercially available, limited data on histological immunodistribution of this inhibin subunit in gynaecological organs exist. Therefore, the aims of the present study were the synthesis and evaluation of a specific antibody against the inhibin-betaE subunit. In this study, we describe the characterisation of a polyclonal antibody against the inhibin-betaE subunit. This antibody demonstrated a specific reaction in both western blot analysis and immunohistochemistry. Moreover, we demonstrated positive immunolabelling in normal human ovary and placenta. The role of this novel subunit is intriguing, especially within the view that the other inhibin/activin subunits might have substantial functions in human reproduction and carcinogenesis. However, the function of this subunit in humans remains still unclear and warrants further research.

Invasive hydatidiform mole: immunohistochemical labelling of inhibin/activin subunits, Ki67, p53 and glycodelin A in a rare case.

Invasive trophoblastic mole is an extremely rare condition. Its early recognition is essential since it can transform into an invasive type of tumour. Immunohistochemistry was performed with monoclonal antibodies against inhibin-alpha, -betaA and -betaB, Ki67, p53 and glycodelin A in a rare case of accidentally diagnosed invasive trophoblastic mole. There was labelling of the inhibin/activin subunits, Ki67 and p53, while glycodelin A showed minimal immunopositivity. Therefore, since the pathological diagnosis of an invasive mole is difficult, the immunohistochemical detection of inhibin/activin subunits, Ki67, p53 and glycodelin A might be additional useful tumour markers.

Interaction of tomato lectin with ABC transporter in cancer cells: glycosylation confers functional conformation of P-gp.

Phospho-glycoprotein (P-gp) is a polytopic plasma membrane protein whose overexpression causes multidrug resistance (MDR) responsible for the failure of cancer chemotherapy. P-gp 170 is a member of the ATP-binding cassette (ABC) transporter superfamily and has two potentially interesting regions for drugs interfering with its efflux function, namely the oligosaccharides on the first extracellular loop with unknown function and the two intracellular ATP-binding regions providing the energy for drug efflux function. The polylactoseamine oligosaccharides on the first loop can specifically bind the tomato lectin (TL). The P-gp efflux activities of TL-pre-treated MDR resistant cells were measured in the presence of structurally unrelated resistance modifiers such as phenothiazines, terpenoids and carotenoids. The inhibition of efflux activity was measured via the increased rhodamine uptake by mouse lymphoma cells transfected in human MDR1 gene and in human brain capillary endothelial cells. The tested resistance modifiers inhibit the function of ABC transporter resulting in increased R123 accumulation in MDR1 expressing cells. TL prevented the inhibitory action of phenothiazine and verapamil on brain capillary endothelial and MDR1-lymphoma cells, presumably due to the stabilization of the functional active conformation of P-gp. Our results indicate that the polylactosamine chains of P-gp are part of the functionally active protein conformation.

Inhibin/activin subunits are immunohistochemically expressed in complete and partial hydatidiform moles.

BACKGROUND AND AIM: Inhibins are dimeric glycoproteins, belonging to the transforming growth factor beta (TGF-beta) family, composed of an alpha-subunit (INH-alpha) and one of two possible beta-subunits (betaA or betaB). Additionally two further beta-subunits (betaC and betaE) have been cloned, although their function remains still quite unclear. The detection by immunohistochemistry of inhibin/activin subunits has been proposed as a useful marker of trophoblastic diseases. Interestingly, a complete mole cannot be easily differentiated from a partial mole. Therefore, the aim of this study was to determine expression changes of the five inhibin/activin subunits in partial and complete moles. MATERIALS AND METHODS: Histologically diagnosed complete (n = 6) and partial (n = 3) hydatidiform moles were immunohistochemical analyzed for INH-alpha, INH-betaA, INH-betaB, INH-betaC and INH-betaE subunits. The immunohistochemical reaction in intermediate trophoblast was analyzed with a semiquantitative score (IRS) and statistical analysis was performed. RESULTS: Immuno-histochemical reaction with INH-alpha, INH-betaA, INH-betaB, INH-betaC and INH-betaE subunits was demonstrated in hydatidiform moles. The INH-betaA and INH-betaB expression was significantly higher in complete compared to partial moles (p < 0.05 each), while INH-alpha, INH-betaC and INH-betaE did not demonstrate any statistically significant differences. CONCLUSION: We demonstrated an immunohistochemical expression of all five inhibin/activin subunits in partial and complete hydatidiform moles. The expression of INH-betaA and INH-betaB determined immunohistochemically was significantly up-regulated in complete moles, suggesting the utilization of these antibodies as diagnostic differentiation markers between complete and partial moles.

Amyloid contained in the knee joint meniscus is formed from apolipoprotein A-I.

OBJECTIVE: To determine the chemical nature of amyloid deposits found in knee joint menisci. METHODS: Amyloid was extracted from the menisci of 3 adults who underwent knee joint replacement surgery. The primary structural features of the purified proteins were determined by sequential Edman degradation and tandem mass spectrometry (MS/MS). Tissue specimens were also subjected to in situ hybridization analysis, as well as complementary DNA cloning by reverse transcriptase-polymerase chain reaction (RT-PCR). Additionally, specimens from these 3 patients, as well as other patients with amyloid in the knee joint menisci, were examined immunohistochemically. RESULTS: Amino acid sequence and MS/MS analyses of the extracts revealed the presence of 60-77-residue components identical to the N-terminal portion of apolipoprotein A-I (Apo A-I). The Apo A-I nature of the amyloid was confirmed by the demonstration that the green birefringent congophilic deposits in the 7 meniscus samples were recognized by an anti-human Apo A-I antibody. That the meniscus itself was the source of the amyloidogenic protein was evidenced through Southern blot analysis, in which an Apo A-I product was generated by RT-PCR from synovial tissue, and further, by the demonstration that the cytoplasm of chondrocytes reacted with the specific Apo A-I probe used for in situ hybridization and was immunostained by the anti-Apo A-I antiserum. CONCLUSION: Amyloid in the knee joint menisci is formed from Apo A-I that is produced by chondrocytes within the meniscal cartilage. This entity represents yet another localized form of amyloidosis associated with the aging process and may be of pathophysiologic import.

Topooptical investigations and enzymatic digestions on tissue-isolated amyloid fibrils.

Chemical and biochemical analysis of isolated amyloid fibrils reveals the presence of different classes of proteins which are often related to distinct clinical forms of amyloidosis and are useful to classify the amyloid deposits. In this study, enzymatic digestions using hyaluronidase, chondroitinase AC and B, neuraminidase, and chemical extractions using mild acid hydrolysis with hydrochloric and sulfuric acid, were used to control the specificity of various topooptical reactions. The disappearance of intense staining after these extraction methods indicates that tissue-isolated amyloid fibrils contain sialic acids and glycosaminoglycans (GAGs). We conclude that topooptical reactions are the most sensitive methods to detect conformational changes in the non-fibrillar component of amyloid deposits and tissue-isolated amyloid fibrils.

Case report: amyloid tumors in a case of non-secretory multiple myeloma.

Multiple myeloma (MM) is a neoplastic disorder characterized by proliferation of a single clone of plasma cells derived from B cells, which proliferates in the bone marrow and frequently invades the adjacent bone, producing skeletal destruction that results in bone pain and fractures. Patients with MM can furthermore present with anemia, hypercalcemia and renal failure. Non-secretory multiple myeloma (NSMM) is characterized by the absence of a monoclonal (M) protein in both the serum and urine. The reported incidence is 1-5% of all multiple myeloma cases. Development of amyloid tumors in NSMM has been described in the literature only occasionally. The clinical features of a 49-year-old female patient with NSMM and amyloid tumors in the breast, lung and rib are presented in this report. Conventional histology, Congo red staining with and without potassium permanganate pretreatment, aldehyde bisulfite-toluidine blue (ABT) reaction, sialic acid specific topo-optical reaction, toluidine blue topo-optical reaction as well as immunohistochemistry were performed. An attempt is made to explain the lack of monoclonal immunoglobulins in the serum and urine, although extensive organ amyloidosis of AL type (kappa-light chains) has been found. It is assumed that the plasmocytic plasma cells possess an excretory mechanism, which allows the pathologic immunoglobulins to be secreted either as amyloid proteins polymerizing into amyloid fibrils, or as immunoglobulin fragments that are subject to degradation as soon as they are excreted out of the tumor cell. In this paper, we review the occurrence of amyloid tumors in non-secretory multiple myeloma and, in a single case report, we confirm the existence of carbohydrate residues, including sialic acids and sulfated GAGs, in amyloid deposits.

Sensitivity and specificity of Congo red staining according to Romhányi. Comparison with Puchtler's or Bennhold's methods.

The sensitivity and specificity of various Congo red staining methods is very important in the diagnosis of amyloidosis. When using a less sensitive staining method, some true positive cases of amyloidosis remain undetected. A more highly specific method potentially detects more cases and reveals amyloidosis in an earlier stage of deposition. In this paper, the Congo red staining method according to Romhányi is discussed in comparison with Puchtler's and Bennhold's methods. Using Romhányi's technique, there is no alcoholic differentiation, and thus no dye molecules are washed off the amyloid filaments. The binding of the oriented dye molecules is optimal for polarization microscopy. With this method, the polar hydrophilic mounting medium, gum Arabic is used. Mounted in this carbohydrate-containing, hydrophilic medium, the Congo red molecules are oriented parallel to the surface of the amyloid filaments and the sign is linear positive, corresponding to an additive character of topo-optical staining reactions. Otherwise, the Congo red molecules are oriented perpendicular to the surface of collagen, reducing the intensity of birefringence and even inducing an inversion of the original sign of the collagen birefringence. With alcoholic differentiation, Congo red dye molecules are extracted and this decreases the birefringence of amyloid deposits, i.e. minimal amyloid deposits may be missed. Using the apolar hydrophobic mounting medium, Canada balsam, an axis-parallel arrangement of Congo red dye molecules on the surface of collagen fibers and amyloid will occur, resulting in an additive topo-optical reaction with a green polarization color and a false positive diagnosis of amyloidosis ("phantom amyloidosis").

Topo-optical visualization reactions of carbohydrate-containing amyloid deposits in the respiratory tract.

Staining with Congo red according to is the most commonly used method for the demonstration of amyloid, but structures other than amyloid can give false-positive results. To overcome this problem, introduced an aqueous Congo red staining with gum arabic as the mounting medium, which we have used in this and previous publications. Most histochemical studies on amyloid deposits to date have concentrated on conventional methods including staining with thioflavine, sirius red, alcian blue, methyl and crystal violet. In this study, we used topo-optical reactions with thiazine dyes on both the light and polarization microscopic level to establish the structure, distribution and location of carbohydrate components that occur within amyloid deposits, especially in the respiratory tract. Topo-optical staining reactions for the qualitative analysis of carbohydrate components in amyloid deposits included (1) reactions that identify the carbohydrate residues, (2) reactions that detect sialic acids and, (3) methods that visualize glycosaminoglycans. In conclusion, a comparison of consecutive serial sections stained with Congo red, aldehyde bisulfite toluidine blue reaction, sialic acid-specific topo-optical reaction, toluidine blue topo-optical reaction and chemically intensified basophilic reaction showed correlative staining patterns and anisotropic effects, corresponding to a close pathomorphological relationship between amyloid fibrils, periodate reactive carbohydrates, including sialic acids, and glycosaminoglycans.

Anastrozole versus tamoxifen treatment in postmenopausal women with endocrine-responsive breast cancer and tamoxifen-induced endometrial pathology.

PURPOSE: To investigate the effect of switching from adjuvant tamoxifen to anastrozole (Arimidex) treatment in postmenopausal women with endocrine-responsive breast cancer and histologically proven tamoxifen-induced benign endometrial pathology. EXPERIMENTAL DESIGN: Two hundred twenty-six postmenopausal women who had received adjuvant tamoxifen 20 mg/d (> or =12 months, < or =48 months) and developed abnormal vaginal bleeding and/or an asymptomatic endometrial thickness >10 mm [measured by transvaginal ultrasound (TVUS)] were subjected to hysteroscopy and dilation and curettage (D&C). Thereafter, 171 patients were randomized in a phase III study to continue tamoxifen treatment (n = 88) or switch to anastrozole 1 mg/d (n = 83). Patients were monitored for < or =42 months using TVUS at 6-monthly intervals. RESULTS: At study entry, there were no significant differences in vaginal bleeding, endometrial thickness, and histologic findings between the two treatment groups. Throughout the treatment period, there was no significant difference in recurrent vaginal bleeding between groups [anastrozole, 4 of 83 (4.8%); tamoxifen, 9 of 88 (10.2%); P = 0.18]. Six months after randomization, the mean endometrial thickness for patients who switched to anastrozole was significantly reduced compared with those who continued tamoxifen treatment (P < 0.0001). Significantly fewer anastrozole patients required a repeat hysteroscopy and D&C compared with those on tamoxifen [4 of 83 (4.8%) and 29 of 88 (33.0%), respectively; P < 0.0001]. Repeat hysteroscopy and D&C revealed endometrial atrophy in all 4 cases in the anastrozole group and 14 polyps, 8 hyperplasias, and 7 atrophies in the tamoxifen group. CONCLUSIONS: Switching from tamoxifen to anastrozole treatment significantly reduced the need for a second hysteroscopy and D&C due to recurrent vaginal bleeding or thickening of the endometrium in postmenopausal breast cancer patients with tamoxifen-induced endometrial abnormalities.

Inhibin/activin subunits beta-A (-betaA) and beta-B (-betaB) are differentially localised in normal, hyperplastic and malignant human endometrial tissue.

Inhibins (INHs) are dimeric glycoproteins composed of an alpha (-alpha) subunit and one of two possible beta (beta-) subunits (betaA or betaB). The aims of this study were to determine the frequency and distribution of INH beta (betaA and betaB) subunits in normal, hyperplastic and malignant human endometrium. Endometrial tissue was obtained from normal, hyperplastic (simple, complex and atypical) and endometrioid adenocarcinoma (EC) and INH-alpha, -betaA and -betaB were labelled using immunohistochemistry and immunofluorescence. INH-betaA and -betaB labelling was increased significantly between the proliferative and secretory phase (p<0.05). The lowest labelling was demonstrated in EC, being significantly lower than in secretory phase (p<0.01) and in simple, complex and atypical hyperplastic tissue (p<0.05). For inhibin-betaB, the most intense labelling was noted in atypical hyperplasia compared to EC (p<0.05). A strong colocalisation of inhibin-alpha and -betaA could be demonstrated in malignant endometrial tissue, suggesting the production of inhibin A within the tumour. Additionally, only limited colocalisation of inhibin-betaB with -alpha subunit could be observed, suggesting the synthesis of activin B rather than inhibin B in malignant endometrium. In conclusion, INH-betaA and -betaB were labelled in normal, hyperplastic and malignant endometrium. Hyperplastic tissue labelled more intensely than EC for the presence of INH-betaA and -betaB, suggesting a substantial function in endometrial pathogenesis and an important role in endometrial carcinogenesis.