Circular RNA 0000654 facilitates the growth of gastric cancer cells through absorbing microRNA-149-5p to up-regulate inhibin-beta A.

Circular (circ) RNAs are differentially expressed in gastric cancer (GC) and participate in the biological growth of tumor cells. Given that, investigations were performed to unravel the function of circ_0000654 in GC. GC tissue and normal tissue specimens were obtained, in which circ_0000654, microRNA (miR)-149-5p, and inhibin-beta A (INHBA) levels were examined. GC cell line (BGC-823) was transfected to alter circ_0000654 and miR-149-5p expression, thereby observing cell malignancy. Stably-transfected BGC-823 cells were injected into nude mice to observe tumor growth in vivo. The interaction circ_0000654, miR-149-5p, and INHBA was validated. circ_0000654 and INHBA were up-regulated but miR-149-5p was down-regulated in GC. circ_0000654 absorbed miR-149-5p to target INHBA. Silencing circ_0000654inhibited the progress of GC cell biology. Oppositely, restoring circ_0000654 enhanced the growth of GC cells. Inhibiting miR-149-5p rescued down-regulated circ_0000654-induced anti-tumor effect on GC. circ_0000654 silence or miR-149-5p overexpression limited the growth of GC tumors in vivo. Obviously, circ_0000654 facilitates the growth of GC cells through absorbing miR-149-5p to up-regulate INHBA.

KLF10 is upregulated in osteoarthritis and inhibits chondrocyte proliferation and migration by upregulating Acvr1 and suppressing inhbb expression.

BACKGROUD: Osteoarthritis (OA) is a common disease caused by chondrocyte dysfunction. KLF10 is a member of the Sp1-like transcription factor family that is involved in regulating osteoblasts, but its expression and regulatory mechanism(s) in chondrocytes are unclear. In the present study, we aimed to investigate the regulatory role of KLF10 on the pathological process of OA. METHODS: KLF10 expression in the cartilaginous tissue of patients with osteoarthritis (OA) was evaluated by immunohistochemistry (IHC). Next, we generated an OA mouse model, and the histological changes in cartilage tissue were verified using H&E staining, Safranin O-Fast Green staining, and IHC assays. KLF10 expression in the articular chondrocytes of OA mice was determined by qRT-PCR and Western blotting. To investigate the role of KLF10 in regulating cell proliferation and migration, a KLF10 overexpression plasmid was constructed and transfected into primary mouse chondrocytes. Subsequently, we used RNA sequencing (RNA-seq) to screen differentially expressed genes in chondrocytes with or without KLF10 overexpression. qRT-PCR was used for verification purposes. RESULTS: We found that KLF10 was upregulated in the cartilaginous tissue of patients with OA as well as in cartilaginous tissue of the OA mouse model. KLF10 overexpression inhibited the proliferation and migration of chondrocytes. Furthermore, RNA sequencing results identified increased expression of Acvr1 and decreased expression of Inhbb in cells overexpressing KLF10. Changes in mRNA expression of Acvr1 and Inhbb were confirmed by qRT-PCR. CONCLUSIONS: KLF10 inhibits chondrocyte proliferation and migration by regulating the expression of Acvr1 and Inhbb in both human and mouse OA. These data suggest that KLF10 may be a potential therapeutic target for the treatment of OA.

Evidence that Melatonin Increases Inhibin Beta-A and Follistatin Gene Expression in Ovaries of Pinealectomized Rats.

Melatonin plays an important role in the regulation of ovarian function including oocyte maturation in different mammalian species. Many studies indicate that melatonin has an impact on the ovarian function of a variety of ovarian cells. However, the information on the exact mechanism and involved hormones is low. To evaluate inhibin beta-A (INHBA) and follistatin (FST) expression in the ovaries of pinealectomized rats treated with melatonin, thirty adult female Wistar rats were randomized into three groups of ten animals each: group 1 (GSh), sham-operated controls receiving vehicle; group 2 (GPx), pinealectomized animals receiving vehicle; and group 3 (GPxMe), pinealectomized animals receiving replacement melatonin (1.0 mg/kg body weight. It was assumed that each animal drank 6.5 ± 1.2 ml per night and weighs approximately 300 g.) for 60 consecutive days. The ovaries were collected for mRNA abundance and protein of INHBA and FST by qRT-PCR and immunohistochemical analyses, respectively. Treatment with melatonin resulted in the upregulation of INHBA and FST genes in the ovarian tissue of the melatonin-treated animals (GPxMe), when compared with GPx. These findings were then confirmed by analyzing the expression of protein by immunohistochemical analyses, which revealed higher immunoreactivity of INHBA and FST in GPxMe animals in the follicular cells compared with GSh and GPx rats. Melatonin increases the expression of INHBA and FST in the ovaries of pinealectomized female rats.

Gene expression analysis during the induction and patterning of the conjunctival papillae in the chick embryonic eye.

The induction and patterning of the conjunctival papillae (i.e. epithelial thickenings of the conjunctiva required for the induction of the underlying, neural crest-derived scleral ossicles) is complex. It takes place over a period of two days and follows a defined spatiotemporal sequence. In this study, we investigated the spatial and temporal expression pattern of four genes over seven morphological stages of development of these papillae. We show that ß-catenin is expressed during the pre-patterning of the epithelium prior to papilla induction and second that ß-catenin, Ednrb and Inhba are expressed during the induction and patterning of the conjunctival papillae. Furthermore, we identified two genes, ß-catenin and Prox1, that may be involved in the induction of the underlying scleral bones. These data provide an excellent baseline for future studies, setting the stage for functional studies aimed at examining the role of these genes in the patterning of the scleral ossicle system. This study also outlines the similarities between the conjunctival papillae and other placodes and may provide insights into the evolution and development of the conjunctival papillae.

Invasion of ovarian cancer cells is induced byPITX2-mediated activation of TGF-ß and Activin-A.

BACKGROUND: Most ovarian cancers are highly invasive in nature and the high burden of metastatic disease make them a leading cause of mortality among all gynaecological malignancies. The homeodomain transcription factor, PITX2 is associated with cancer in different tissues. Our previous studies demonstrated increased PITX2 expression in human ovarian tumours. Growing evidence linking activation of TGF-ß pathway by homeodomain proteins prompted us to look for the possible involvement of this signalling pathway in PITX2-mediated progression of ovarian cancer. METHODS: The status of TGF-ß signalling in human ovarian tissues was assessed by immunohistochemistry. The expression level of TGFB/INHBA and other invasion-associated genes was measured by quantitative-PCR (Q-PCR) and Western Blot after transfection/treatments with clones/reagents in normal/cancer cells. The physiological effect of PITX2 on invasion/motility was checked by matrigel invasion and wound healing assay. The PITX2- and activin-induced epithelial-mesenchymal transition (EMT) was evaluated by Q-PCR of respective markers and confocal/phase-contrast imaging of cells. RESULTS: Human ovarian tumours showed enhanced TGF-ß signalling. Our study uncovers the PITX2-induced expression of TGFB1/2/3 as well as INHBA genes (p < 0.01) followed by SMAD2/3-dependent TGF-ß signalling pathway. PITX2-induced TGF-ß pathway regulated the expression of invasion-associated genes, SNAI1, CDH1 and MMP9 (p < 0.01) that accounted for enhanced motility/invasion of ovarian cancers. Snail and MMP9 acted as important mediators of PITX2-induced invasiveness of ovarian cancer cells. PITX2 over-expression resulted in loss of epithelial markers (p < 0.01) and gain of mesenchymal markers (p < 0.01) that contributed significantly to ovarian oncogenesis. PITX2-induced INHBA expression (p < 0.01) contributed to EMT in both normal and ovarian cancer cells. CONCLUSIONS: Overall, our findings suggest a significant contributory role of PITX2 in promoting invasive behaviour of ovarian cancer cells through up-regulation of TGFB/INHBA. We have also identified the previously unknown involvement of activin-A in promoting EMT. Our work provides novel mechanistic insights into the invasive behavior of ovarian cancer cells. The extension of this study have the potential for therapeutic applications in future.

Re-evaluating the role of activin-ßC in cancer biology.

Transforming growth factor-ß (TGF-ß) superfamily signaling pathway and its ligands are essential regulators of cellular processes such as proliferation, differentiation, migration, and survival. Alteration of this pathway results in uncontrolled proliferation and cancer progression. This review focuses on a specific member of the TGF-ß superfamily: activin-ßC. After its initial discovery, activin-ßC has been considered non-biologically relevant. Therefore, for years several experimental designs have ignored the potential contribution of this molecule to the final biological outcome. Here we focus on recent advances in the activin field, with a particular emphasis on activin-ßC, its antagonistic mechanism, and the physiological relevance of activin-ßC actions in reproductive and cancer biology. Covering a novel and previously unexplored function of activin-ßC on cancer associated weight loss and muscle metabolism, this review suggests an imminent need to re-evaluate the function of activin-ßC in biological systems and advances the understanding of how activin-ßC antagonizes the activin signaling pathway. Thus, challenging activin biologists to consider the impact of activin-ßC when interpreting their work.

Follistatin, an activin antagonist, ameliorates renal interstitial fibrosis in a rat model of unilateral ureteral obstruction.

Activin, a member of the TGF-ß superfamily, regulates cell growth and differentiation in various cell types. Activin A acts as a negative regulator of renal development as well as tubular regeneration after renal injury. However, it remains unknown whether activin A is involved in renal fibrosis. To clarify this issue, we utilized a rat model of unilateral ureteral obstruction (UUO). The expression of activin A was significantly increased in the UUO kidneys compared to that in contralateral kidneys. Activin A was detected in glomerular mesangial cells and interstitial fibroblasts in normal kidneys. In UUO kidneys, activin A was abundantly expressed by interstitial α-SMA-positive myofibroblasts. Administration of recombinant follistatin, an activin antagonist, reduced the fibrotic area in the UUO kidneys. The number of proliferating cells in the interstitium, but not in the tubules, was significantly lower in the follistatin-treated kidneys. Expression of α-SMA, deposition of type I collagen and fibronectin, and CD68-positive macrophage infiltration were significantly suppressed in the follistatin-treated kidneys. These data suggest that activin A produced by interstitial fibroblasts acts as a potent profibrotic factor during renal fibrosis. Blockade of activin A action may be a novel approach for the prevention of renal fibrosis progression.

Mesenchymal precursor cells maintain the differentiation and proliferation potentials of breast epithelial cells.

INTRODUCTION: Stromal-epithelial interactions play a fundamental role in tissue homeostasis, controlling cell proliferation and differentiation. Not surprisingly, aberrant stromal-epithelial interactions contribute to malignancies. Studies of the cellular and molecular mechanisms underlying these interactions require ex vivo experimental model systems that recapitulate the complexity of human tissue without compromising the differentiation and proliferation potentials of human primary cells. METHODS: We isolated and characterized human breast epithelial and mesenchymal precursors from reduction mammoplasty tissue and tagged them with lentiviral vectors. We assembled heterotypic co-cultures and compared mesenchymal and epithelial cells to cells in corresponding monocultures by analyzing growth, differentiation potentials, and gene expression profiles. RESULTS: We show that heterotypic culture of non-immortalized human primary breast epithelial and mesenchymal precursors maintains their proliferation and differentiation potentials and constrains their growth. We further describe the gene expression profiles of stromal and epithelial cells in co-cultures and monocultures and show increased expression of the tumor growth factor beta (TGFß) family member inhibin beta A (INHBA) in mesenchymal cells grown as co-cultures compared with monocultures. Notably, overexpression of INHBA in mesenchymal cells increases colony formation potential of epithelial cells, suggesting that it contributes to the dynamic reciprocity between breast mesenchymal and epithelial cells. CONCLUSIONS: The described heterotypic co-culture system will prove useful for further characterization of the molecular mechanisms mediating interactions between human normal or neoplastic breast epithelial cells and the stroma, and will provide a framework to test the relevance of the ever-increasing number of oncogenomic alterations identified in human breast cancer.

Relation of INHBA gene expression to outcomes in gastric cancer after curative surgery.

Inhibin-ßA (INHBA), a ligand belonging to the transforming growth factor-ß superfamily, is associated with cell proliferation in cancer. We studied the relations of INHBA gene expression to clinicopathological factors and outcomes in 168 patients with gastric cancer who underwent curative surgery. Relative INHBA gene expression was measured in surgical specimens of cancer tissue and adjacent normal mucosa by quantitative real-time, reverse-transcription polymerase chain reaction. INHBA expression levels were significantly higher in cancer tissue than in adjacent normal mucosa and were related to TNM stage and venous invasion. High INHBA gene expression was associated with significantly poorer 5-year overall survival than was low expression. On multivariate analysis, INHBA gene expression was an independent prognostic factor. Overexpression of the INHBA gene is considered a useful independent predictor of outcomes in patients with gastric cancer after curative surgery.

Increased decidual mRNA expression levels of candidate maternal pre-eclampsia susceptibility genes are associated with clinical severity.

INTRODUCTION: Pre-eclampsia (PE) has a familial association, with daughters of women who had PE during pregnancy having more than twice the risk of developing PE themselves. Through genome-wide linkage and genetic association studies in PE-affected families and large population samples, we previously identified the following as positional candidate maternal susceptibility genes for PE; ACVR1, INHA, INHBB, ERAP1, ERAP2, LNPEP, COL4A1 and COL4A2. The aims of this study were to determine mRNA expression levels of previously identified candidate maternal pre-eclampsia susceptibility genes from normotensive and severe PE (SPE) pregnancies and correlate mRNA expression levels with the clinical severity of SPE. METHODS: Third trimester decidual tissues were collected from both normotensive (n = 21) and SPE pregnancies (n = 24) and mRNA expression levels were determined by real-time PCR. Gene expression was then correlated with several parameters of clinical severity in SPE. Statistical significance was determined by Mann-Whitney U test and Spearman's Correlation. RESULTS: The data demonstrate significantly increased decidual mRNA expression levels of ACVR1, INHBB, ERAP1, ERAP2, LNPEP, COL4A1 and COL4A2 in SPE (p < 0.05). Increased mRNA expression levels of several genes - INHA, INHBB, COL4A1 and COL4A2 were correlated with earlier onset of PE and earlier delivery of the fetus (p < 0.05). CONCLUSION: These results suggest altered expression of maternal susceptibility genes may play roles in PE development and the course of disease severity.

Significance of INHBA expression in human colorectal cancer.

Inhibin ß A (INHBA) is a member of the transforming growth factor ß (TGF-ß) superfamily. INHBA expression is associated with several types of human cancers; however, its significance in colorectal cancer (CRC) is not fully understood. INHBA expression was studied in 126 primary CRC samples and 4 CRC cell lines. Cell growth was assessed after inhibition of INHBA expression or after exogenous overexpression of INHBA in CRC tissues. INHBA expression was significantly higher in CRC tissues when compared to that in the corresponding normal tissues (P<0.001). Patients in the high expression group showed a poorer overall survival rate when compared to those in the low expression group (P<0.001); the present study did not evaluate for an independent prognostic factor but showed the significance of lymph node metastasis as an independent prognostic factor. The present study suggests that INHBA is useful as a predictive marker for prognosis in CRC patients.

Inhibin beta E is upregulated by drug-induced endoplasmic reticulum stress as a transcriptional target gene of ATF4.

Inhibins and activins are gonadal peptide hormones of the transforming growth factor-ß super family with important functions in the reproductive system. By contrast, the recently identified inhibin ßE subunit, primarily expressed in liver cells, appears to exert functions unrelated to the reproductive system. Previously shown downregulation of inhibin ßE in hepatoma cells and anti-proliferative effects of ectopic inhibin ßE overexpression indicated growth-regulatory effects of inhibin ßE. We observed a selective re-expression of the inhibin ßE subunit in HepG2 hepatoblastoma cells, MCF7 breast cancer cells, and HeLa cervical cancer cells under endoplasmic reticulum stress conditions induced by tunicamycin, thapsigargin, and nelfinavir. Analysis of XPB1 splicing and ATF4 activation revealed that inhibin ßE re-expression was associated with induction of the endoplasmic reticulum stress reaction by these drugs. Transfection of an ATF4 expression plasmid specifically induced inhibin ßE expression in HeLa cells and indicates inhibin ßE as a hitherto unidentified target gene of ATF4, a key transcription factor of the endoplasmic reticulum stress response. Therefore, the inhibin ßE subunit defines not only a new player but also a possible new marker for drug-induced endoplasmic reticulum stress.

Expression of inhibin/activin proteins and receptors in the human hypothalamus and basal forebrain.

The inhibin/activin family of proteins is known to have a broad distribution of synthesis and expression in many species, as well as a variety of functions in reproductive and other physiological systems. Yet, our knowledge regarding the production and function of inhibin and activin in the central nervous system is relatively limited, especially in humans. The present study aimed to explore the distribution of inhibin/activin protein subunits and receptors in the adult human brain. The human hypothalamus and surrounding basal forebrain was examined using post-mortem tissues from 29 adults. Immunocytochemical studies were conducted with antibodies directed against the inhibin/activin α, ßA, and ßB subunits, betaglycan and the activin type IIA and IIB receptors. An immunoassay was also utilised to measure dimeric inhibin A and B levels in tissue homogenates of the infundibulum of the hypothalamus. Robust ßA subunit immunoreactivity was present in the paraventricular, supraoptic, lateral hypothalamic, infundibular, dorsomedial and suprachiasmatic nuclei of the hypothalamus, in the basal ganglia, and in the nucleus basalis of Meynert. A similar staining distribution was noted for the ßB subunit, betaglycan and the type II receptor antibodies, whereas α subunit staining was not detected in any of the major anatomical regions of the human brain. Inhibin B immunoreactivity was present in all tissues, whereas inhibin A levels were below detectable limits. These studies show for the first time that the inhibin/activin protein subunits and receptors can be co-localised in the human brain, implicating potential, diverse neural functions.

Inhibin beta B: a useful tumor marker in uterine endometrioid adenocarcinomas?

Inhibins, dimeric peptide hormones composed of an alpha-subunit and one of two possible beta-subunits (betaA or betaB), exhibit substantial roles in human reproduction and in endocrine-responsive tumours. However, the prognostic significance and clinical implications of the inhibin-betaB subunit in uterine endometrioid adenocarcinomas is still not defined yet. A series of 227 uterine endometrioid adenocarcinomas of a previous well-characterized cohort were re-evaluated for the expression of the inhibin-betaB subunit and correlated with several clinicopathological characteristics and the clinical outcome. In this re-analysis, the betaB-subunit expression demonstrated a significant association with the patients' age and cervical involvement. However, inhibin-betaB did not significantly affect the patients survival in this large cohort group. However, patients with a higher intensity of betaB-subunit immunolabelling had a slightly worse survival expectation, although without any significant association, suggesting that this subunit might have a substantial role in the carcinogenesis and pathology of endometrioid adenocarcinomas. Thus, the inhibin-betaB subunit appears not to be a useful prognostic marker regarding endometrioid adenocarcinomas. However, further research is warranted in elucidating the possible implications of inhibin-ßB and endometrial carcinogenesis.

Inhibin/activin betaE-subunit in uterine endometrioid adenocarcinoma and endometrial cancer cell lines: from immunohistochemistry to clinical testing?

OBJECTIVE: Inhibins and activins are important regulators of the female reproductive system and have also been described to be involved in gynecologic cancer development. A new inhibin/activin subunit betaE has been identified, but only limited data on its expression in human uterine adenocarcinomas and endometrial cancer cell lines exist. METHODS: A series of 223 uterine endometrial adenocarcinomas were immunohistochemically analyzed with a specific antibody against the inhibin betaE-subunit. In addition, established endometrial cancer cell lines were analyzed for the synthesis of the inhibin betaE subunit by immunofluorescence and RT-PCR analysis. RESULTS: In this analysis, the inhibin betaE staining intensity was associated with histological grading along with a significant decrease in cases with ovarian invasion. However, inhibin-betaE did not affect patient survival nor did it constitute an independent prognostic parameter in endometrial adenocarcinoma patients. Additionally, the inhibin/activin betaE-subunit was found to be expressed in the human endometrial carcinoma cell lines HEC1a, HEC1b, Ishikawa, and RL95-2, although the level of expression was found to be highly differing among the cancer cell lines tested. CONCLUSION: The isolated analysis of the inhibin betaE subunit might be of minor prognostic value in identifying high-risk patients. However, its differential expression in cancer of different histological differentiation and ovarian metastasis suggests a putative but yet undefined role in endometrial carcinogenesis. Whether this novel and not well studied inhibin subunit has a substantial function in the pathogenesis and malignant transformation of human endometrium is still under investigation.

Involvement of activin signaling in abnormalities of mouse vagina exposed neonatally to diethylstilbestrol.

Perinatal exposure to a synthetic estrogen, diethylstilbestrol (DES), causes cervicovaginal adenosis and permanent hyperplastic cornified vaginal epithelium with keratinization in mice. To investigate the mechanisms of the induction of vaginal abnormalities by DES, we have focused on activin A signaling. We have found that the ßA-subunit mRNA is mainly expressed in the neonatal vaginal stroma, whereas activin A receptor type IB is localized in the neonatal vaginal epithelium. SMAD2, the intracellular signaling protein, is phosphorylated in the neonatal vagina. Cell proliferation in the vaginal epithelium grown in vitro is reduced by DES treatment or by activin signaling suppression through inhibin treatment. Thus, activin A (a homodimer of the ßA-subunit) in the stroma stimulates epithelial cell proliferation in the neonatal vagina. DES treatment decreases the expression of the ßA-subunit and activin receptor IIB but increases the expression of the ßB-subunit and inhibin receptor. Neonatal DES treatment inhibits the phosphorylation of SMAD2 in the vaginal epithelium, indicating the inhibition of activin A signaling in the vaginal epithelium by neonatal DES treatment. Treatment with DES or inhibin, a native antagonist of activin, induces adenosis-like structures and keratinization in the vagina grown in vitro. These data suggest that the suppression of activin A signaling by DES is involved in the induction of cervicovaginal adenosis and keratinization in the neonatal mouse vaginal epithelium.

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.

Immunolabelling of the inhibin/activin-ßC subunit in normal and malignant human uterine cervical tissue and cervical cancer cell lines.

Inhibins are dimeric glycoproteins, composed of an α-subunit and one of two possible ß-subunits (ßA or ßB), with substantial roles in human reproduction and in endocrine-responsive tumours. Recently a novel ß subunit named ßC was described, although it is still unclear if normal or cancerous cervical epithelial cells as well as cervical cancer cell lines can synthesise the inhibin-ßC subunit. Four normal cervical tissue samples together with specimens of well-differentiated squamous cervical cancer and adenocarcinoma of the cervix were immunohistochemically analyzed. Additionally, two cervical carcinoma cell lines (HeLa and CaSKi) were analyzed by immunofluorescence for the expression of this novel subunit. We demonstrated for the first time an immunolabelling of the inhibin-ßC subunit in normal and malignant cervical tissue, as well as cervical cancer cells. Although the physiological role is still unclear in cervical tissue, the inhibin-ßC subunit might play important roles in carcinogenesis. Moreover, the synthesis of this subunit in cervical carcinoma cell lines of squamous and epithelial origins allows the use of these cell lines in elucidating its functions in cervical pathogenesis.

Evidence of inhibin/activin subunit betaC and betaE synthesis in normal human endometrial tissue.

BACKGROUND: Inhibins are important regulators of the female reproductive system. Recently, two new inhibin subunits betaC and betaE have been described, although it is unclear if they are synthesized in normal human endometrium. METHODS: Samples of human endometrium were obtained from 82 premenopausal, non-pregnant patients undergoing gynecological surgery for benign diseases. Endometrium samples were classified according to anamnestic and histological dating into proliferative (day 1-14, n = 46), early secretory (day 15-22, n = 18) and late secretory phase (day 23-28, n = 18). Immunohistochemical analyses were performed with specific antibodies against inhibin alpha (n = 81) as well as inhibin betaA (n = 82), betaB (n = 82), betaC (n = 74) and betaE (n = 76) subunits. RT-PCR was performed for all inhibin subunits. Correlation was assessed with the Spearman factor to assess the relationship of inhibin-subunits expression within the different endometrial samples. RESULTS: The novel inhibin betaC and betaE subunits were found in normal human endometrium by immunohistochemical and molecular techniques. Inhibin alpha, betaA, betaB and betaE subunits showed a circadian expression pattern, being more abundant during the late secretory phase than during the proliferative phase. Additionally, a significant correlation between inhibin alpha and all inhibin beta subunits was observed. CONCLUSIONS: The differential expression pattern of the betaC- and betaE-subunits in normal human endometrial tissue suggests that they function in endometrial maturation and blastocyst implantation. However, the precise role of these novel inhibin/activin subunits in human endometrium is unclear and warrants further investigation.

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.