Production of activin A in hyperplasia and adenocarcinoma of the human endometrium

Advances in cancer cachexia: Intersection between affected organs, mediators, and pharmacological interventions

Advanced cancer patients exhibit cachexia, a condition characterized by a significant reduction in the body weight predominantly from loss of skeletal muscle and adipose tissue. Cachexia is one of the major causes of morbidity and mortality in cancer patients. Decreased food intake and multi-organ energy imbalance in cancer patients worsen the cachexia syndrome. Cachectic cancer patients have a low tolerance for chemo- and radiation therapies and also have a reduced quality of life. The presence of tumors and the current treatment options for cancer further exacerbate the cachexia condition, which remains an unmet medical need. The onset of cachexia involves crosstalk between different organs leading to muscle wasting. Recent advancements in understanding the molecular mechanisms of skeletal muscle atrophy/hypertrophy and adipose tissue wasting/browning provide a platform for the development of new targeted therapies. Therefore, a better understanding of this multifactorial disorder will help to improve the quality of life of cachectic patients. In this review, we summarize the metabolic mediators of cachexia, their molecular functions, affected organs especially with respect to muscle atrophy and adipose browning and then discuss advanced therapeutic approaches to cancer cachexia.

Esophageal squamous cell carcinoma invasion is inhibited by Activin A in ACVRIB-positive cells

Background

Esophageal squamous cell carcinoma (ESCC) is a global public health issue, as it is the eighth most common cancer worldwide. The mechanisms behind ESCC invasion and progression are still poorly understood, and warrant further investigation into these processes and their drivers. In recent years, the ligand Activin A has been implicated as a player in the progression of a number of cancers. The objective of this study was to investigate the role of Activin A signaling in ESCC.

Methods

To investigate the role Activin A plays in ESCC biology, tissue microarrays containing 200 cores from 120 ESCC patients were analyzed upon immunofluorescence staining. We utilized three-dimensional organotypic reconstruct cultures of dysplastic and esophageal squamous tumor cells lines, in the context of fibroblast-secreted Activin A, to identify the effects of Activin A on cell invasion and determine protein expression and localization in epithelial and stromal compartments by immunofluorescence. To identify the functional consequences of stromal-derived Activin A on angiogenesis, we performed endothelial tube formation assays.

Results

Analysis of ESCC patient samples indicated that patients with high stromal Activin A expression had low epithelial ACVRIB, the Activin type I receptor. We found that overexpression of stromal-derived Activin A inhibited invasion of esophageal dysplastic squamous cells, ECdnT, and TE-2 ESCC cells, both positive for ACVRIB. This inhibition was accompanied by a decrease in expression of the extracellular matrix (ECM) protein fibronectin and podoplanin, which is often expressed at the leading edge during invasion. Endothelial tube formation was disrupted in the presence of conditioned media from fibroblasts overexpressing Activin A. Interestingly, ACVRIB-negative TE-11 cells did not show the prior observed effects in the context of Activin A overexpression, indicating a dependence on the presence of ACVRIB.

Conclusions

We describe the first observation of an inhibitory role for Activin A in ESCC progression that is dependent on the expression of ACVRIB.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2920-y) contains supplementary material, which is available to authorized users.

Targeting the myostatin signaling pathway to treat muscle wasting diseases

PURPOSE OF REVIEW

To understand the mechanisms of muscle wasting and how inhibiting myostatin signaling affects them.

RECENT FINDINGS

Myostatin signaling is critical for the understanding of the pathogenesis of muscle wasting as blocking signaling mitigates muscle losses in rodent models of catabolic diseases including cancer, chronic kidney, or heart failure.

SUMMARY

Muscle wasting increases the risks of morbidity and mortality. But, the reliability of estimates of the degree of muscle wasting is controversial as are definitions of terms like cachexia. Much information has been learnt about the pathophysiology of muscle wasting, including the major role of the ubiquitin-proteasome system (UPS) which along with other proteases degrades protein and limits protein synthesis. In contrast, few successful strategies for reversing muscle loss have been tested. Several catabolic conditions are characterized by inflammation, increased glucocorticoid production, and impaired intracellular signaling in response to insulin and IGF-1. These characteristics lead to activation of the UPS and other proteases producing muscle wasting. Another potential initiator of muscle wasting is myostatin and its expression is increased in muscles of animal models and patients with certain catabolic conditions. Myostatin is a member of the TGF-β family; it suppresses muscle growth and its absence stimulates muscle growth substantially. Recently, pharmacologic suppression of myostatin was found to counteract inflammation, increased glucocorticoids and impaired insulin/IGF-1 signaling and most importantly, prevents muscle wasting in rodent models of cancer and kidney failure. Myostatin antagonism as a therapy for patients with muscle wasting should become a topic of clinical investigation.

Reversal of cancer cachexia and muscle wasting by ActRIIB antagonism leads to prolonged survival

Muscle wasting and cachexia have long been postulated to be key determinants of cancer-related death, but there has been no direct experimental evidence to substantiate this hypothesis. Here, we show that in several cancer cachexia models, pharmacological blockade of ActRIIB pathway not only prevents further muscle wasting but also completely reverses prior loss of skeletal muscle and cancer-induced cardiac atrophy. This treatment dramatically prolongs survival, even of animals in which tumor growth is not inhibited and fat loss and production of proinflammatory cytokines are not reduced. ActRIIB pathway blockade abolished the activation of the ubiquitin-proteasome system and the induction of atrophy-specific ubiquitin ligases in muscles and also markedly stimulated muscle stem cell growth. These findings establish a crucial link between activation of the ActRIIB pathway and the development of cancer cachexia. Thus ActRIIB antagonism is a promising new approach for treating cancer cachexia, whose inhibition per se prolongs survival.

Activin A increases invasiveness of endometrial cells in an in vitro model of human peritoneum

The aim of this study was to investigate whether activin A has an effect on the attachment and/or invasion of endometrial cells in a modeled peritoneum in vitro. Cultured endometrial stromal cells (ESCs) and endometrial epithelial cells (EECs) were treated with activin A (6.25-50 ng/ml) and with activin A (25 ng/ml) with and without inhibin A or follistatin. Fluorescent labeled cells were added to confluent peritoneal mesothelial cells (PMCs) and to a monolayer of confluent PMCs grown in a Matrigel invasion assay. The rate of endometrial cell attachment and invasion through PMCs was assessed. The expression of cell adhesion proteins N- and E-cadherin was evaluated with real-time RT-PCR. Activin A (25 ng/ml) promoted invasion of the endometrial cells through the modeled peritoneum (>2-fold versus control) and this effect was partially reversed by inhibin A and follistatin. Activin A had no effect on the rate of attachment of the endometrial cells to the PMCs or in the rate of proliferation. In addition, activin A induced a decreased mRNA expression of E-cadherin in cultured EECs. In conclusion, activin A increases invasion of EECs and ESCs into modeled peritoneum. In EECs, this effect may be related to down-regulation of E-cadherin expression. Further studies are warranted to evaluate the role of activin-A in the genesis of the endometriotic lesion.

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.

Inhibin alpha-subunit and the inhibin coreceptor betaglycan are downregulated in endometrial carcinoma

OBJECTIVE

In the present study we evaluated the protein distribution and mRNA levels of inhibin alpha-subunit and its coreceptor betaglycan in endometrial adenocarcinoma.

DESIGN

Two groups of postmenopausal women were studied: the first group had recently diagnosed endometrial adenocarcinoma (n = 16; age range 61-79 years), and the second group (n = 12; age range 64-78 years) had undergone hysterectomy for uterine prolapse and served as control.

METHODS

Inhibin alpha-subunit and betaglycan gene expression and tissue distribution were evaluated by semiquantitative RT-PCR and immunohistochemistry respectively.

RESULTS

Inhibin alpha-subunit and betaglycan mRNAs were expressed by both healthy and tumoral endometria, but their expression was significantly lower in endometrial carcinoma (P < 0.001, based on Student's t test). Inhibin alpha-subunit expression was much weaker in the glands of tumours than in non-neoplastic specimens. Betaglycan protein was identified in the epithelial cells lining non-tumoral endometrium, and in endothelial cells of both normal and tumoral endometria. Well-differentiated neoplastic cells had a faint and scarce betaglycan staining, and poorly differentiated cells did not express betaglycan at all.

CONCLUSIONS

The lower inhibin alpha and betaglycan expression in endometrial adenocarcinoma suggests that the inhibin action may be disrupted. However, the expression of betaglycan in the endothelia of the tumour vasculature suggests that a selective vascular response to inhibin may be possible in these tumours.

Paracrine regulation of endometrial function: interaction between progesterone and corticotropin-releasing factor (CRF) and activin A

Under the influence of ovarian steroid hormones, endometrial cells aer able to produce a wide variety of growth factors and peptide hormones that area believed to promote: (1) physiological growth and differentiation during the endometrial cycle; (2) decidualization, an essential preparative event for establishment of pregnancy; and (3) pathological growth and differentiation in endometriosis and cancer. Among the local factors produced by the human endometrium, corticotropin-releasing factor (CRF) and activin A have been evaluated in terms of localization and effects. CRF is a neuropeptide expressed by the epithelial and stromal cells of the human endometrium in increasing amounts from the endometrial proliferative to the secretory phase. CRF expression also increases in the pregnant endometrium, from early in the pregnancy until term. CRF-type 1 receptor mRNA is only expressed by stromal cells. Progesterone induces CRF gene expression and release from decidualized cells and CRF decidualizes cultured stromal endometrial cells. Urocortin, a CRF-related peptide, has been identified in endometrial epithelial and stromal cells, and its function is still under investigation. Activin A is a growth factor expressed in increasing amounts throughout endometrial phases by both epithelial and stromal cells. This growth factor is secreted into the uterine cavity with higher levels in the secretory phase. Maternal decidua expresses activin A mRNA in increasing amounts from early pregnancy until term. Human endometrium also expresses activin-A receptors and follistatin, its binding protein. Activin A decidualizes cultured human endometrial stromal cells (an effect reversed by follistatin) and modulates embryonic trophoblast differentiation and adhesion. Activin A is expressed in endometriosis and endometrial adenocarcinoma.