Unraveling the expression of the oncogene YAP1, a Wnt/beta-catenin target, in adrenocortical tumors and its association with poor outcome in pediatric patients

Wnt/β-catenin signaling pathway in the tumor progression of adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is an uncommon, aggressive endocrine malignancy with a high rate of recurrence, a poor prognosis, and a propensity for metastasis. Currently, only mitotane has received certification from both the US Food and Drug Administration (FDA) and the European Medicines Agency for the therapy of advanced ACC. However, treatment in the advanced periods of the disorders is ineffective and has serious adverse consequences. Completely surgical excision is the only cure but has failed to effectively improve the survival of advanced patients. The aberrantly activated Wnt/β-catenin pathway is one of the catalysts for adrenocortical carcinogenesis. Research has concentrated on identifying methods that can prevent the stimulation of the Wnt/β-catenin pathway and are safe and advantageous for patients in view of the absence of effective treatments and the frequent alteration of the Wnt/β-catenin pathway in ACC. Comprehending the complex connection between the development of ACC and Wnt/β-catenin signaling is essential for accurate pharmacological targets. In this review, we summarize the potential targets between adrenocortical carcinoma and the Wnt/β-catenin signaling pathway. We analyze the relevant targets of drugs or inhibitors that act on the Wnt pathway. Finally, we provide new insights into how drugs or inhibitors may improve the treatment of ACC.

Vitamin D receptor activation is a feasible therapeutic target to impair adrenocortical tumorigenesis

OBJECTIVE

To evaluate the therapeutic potential of vitamin D receptor (VDR) signaling in adrenocortical carcinoma (ACC) cells.

METHODS

We evaluated VDR's methylation pattern in H295R ACC cells, and investigated the effects of calcitriol and seocalcitol treatments on adrenocortical tumorigenesis.

RESULTS

VDR was hypermethylated and underexpressed in basal H295R cells. Treatments with calcitriol and seocalcitol restored VDR signaling, resulted in antiproliferative effects, and impaired Wnt/B-catenin signaling. RNAseq of treated cells demonstrated VDR activation on steroid hormones biosynthesis and Rap1 signaling, among others. In vivo, seocalcitol constrained the growth of H295R xenografts and reduced autonomous tumor steroid secretion without hypercalcemia-associated side effects.

CONCLUSIONS

H295R cells present VDR hypermethylation, which can be responsible for its underexpression and signaling inactivation under basal conditions. VDR signaling promoted antiproliferative effects in vitro and in vivo, suggesting that it may be a potential therapeutic target for ACC and a valuable tool for patient's clinical management.

Vitamin D receptor hypermethylation as a biomarker for pediatric adrenocortical tumors

OBJECTIVE

Pediatric adrenocortical tumors (pACT) display complex genomic backgrounds, lacking robust prognostic markers and targeted therapeutic options. Vitamin D3 receptor (VDR) promoter hypermethylation and underexpression were reported in adrenocortical carcinomas from adult patients. In this study, we aimed to investigate VDR expression levels and methylation status in pACT and their clinical and prognostic significance.

DESIGN

Retrospective cross-sectional study enrolling pediatric patients with ACT from two tertiary referral institutions.

METHODS

We evaluated clinicopathological features, VDR mRNA (qPCR) and protein (immunohistochemistry) expression, and VDR-wide methylation of ACT samples from 108 pediatric patients. Fourteen pediatric and 32 fetal and postnatal normal adrenals were used as controls.

RESULTS

Unlike in pre- and post-natal normal adrenals, most pACT lacked nuclear VDR expression and had reduced mRNA levels, especially the carcinomas. Unsupervised analysis of VDR methylation data revealed two groups of pACT with distinct disease features and outcomes. Tumors with high VDR methylation presented lower mRNA levels, and the respective patients presented advanced disease and reduced disease-free and overall survival.

CONCLUSIONS

VDR has a role in normal adrenocortical development and homeostasis, which is impaired during tumorigenesis. VDR hypermethylation and underexpression may be both predictive and prognostic biomarkers for pACT.

[Adrenal glands stem cells: general signaling pathways]

 Nowadays stem cells of adult type are attractive in case of active development of cell and genome technologies. They are the target of new therapeutic approaches, which are based on correction of mutations or replenishment of organs, that were damaged by autoimmune reactions, aging or other pathological processes. Also stem cells, including patient-specific (induced Pluripotent Stem Cells, iPSCs), and obtained by differentiation from them tissue cultures and organoids are the closest models to in vivo researches on humans, which gives an opportunity to get more relevant data while testing different therapeutic approaches and pharmacological drugs. The main molecular pathways, that are essential for homeostasis of a cortex of a adrenal gland - compound, structurally and functionally heterogeneous organ, is described the presented review. The adrenal cortex is renewing during the organism's ontogenesis at the expense of the pool of stem and progenitors cells, which are in tight junctions with differentiated steroidogenic cells and which are under constant control of endocrine and paracrine signals. The understanding of signaling pathways and interactions of different cell types will give an opportunity to develop the most suitable protocols for obtaining cells of adrenal gland cortex in a different stages of differentiation to use them in scientific and medical purposes.

Adrenocortical Carcinoma in Childhood: A Systematic Review

Adrenocortical tumors are rare in children. This systematic review summarizes the published evidence on pediatric adrenocortical carcinoma (ACC) to provide a basis for a better understanding of the disease, investigate new molecular biomarkers and therapeutic targets, and define which patients may benefit from a more aggressive therapeutic approach. We included 137 studies with 3680 ACC patients (~65% female) in our analysis. We found no randomized controlled trials, so this review mainly reflects retrospective data. Due to a specific mutation in the TP53 gene in ~80% of Brazilian patients, that cohort was analyzed separately from series from other countries. Hormone analysis was described in 2569 of the 2874 patients (89%). Most patients were diagnosed with localized disease, whereas 23% had metastasis at primary diagnosis. Only 72% of the patients achieved complete resection. In 334 children (23%), recurrent disease was reported: 81%-local recurrence, 19% (n = 65)-distant metastases at relapse. Patients < 4 years old had a different distribution of tumor stages and hormone activity and better overall survival (p < 0.001). Although therapeutic approaches are typically multimodal, no consensus is available on effective standard treatments for advanced ACC. Thus, knowledge regarding pediatric ACC is still scarce and international prospective studies are needed to implement standardized clinical stratifications and risk-adapted therapeutic strategies.

Adrenal cortex renewal in health and disease

Resident progenitor and/or stem cell populations in the adult adrenal cortex enable cortical cells to undergo homeostatic renewal and regeneration after injury. Renewal occurs predominantly in the outer layers of the adrenal gland but newly formed cells undergo centripetal migration, differentiation and lineage conversion in the process of forming the different functional steroidogenic zones. Over the past 10 years, advances in the genetic characterization of adrenal diseases and studies of mouse models with altered adrenal phenotypes have helped to elucidate the molecular pathways that regulate adrenal tissue renewal, several of which are fine-tuned via complex paracrine and endocrine influences. Moreover, the adrenal gland is a sexually dimorphic organ, and testicular androgens have inhibitory effects on cell proliferation and progenitor cell recruitment in the adrenal cortex. This Review integrates these advances, including the emerging role of sex hormones, into existing knowledge on adrenocortical cell renewal. An in-depth understanding of these mechanisms is expected to contribute to the development of novel therapies for severe endocrine diseases, for which current treatments are unsatisfactory.

Inhibition of Aurora kinase A activity enhances the antitumor response of beta-catenin blockade in human adrenocortical cancer cells

Adrenocortical cancer (ACC) is a rare and aggressive type of endocrine tumor with high risk of recurrence and metastasis. The overall survival of patients diagnosed with ACC is low and treatment for metastatic stages remain limited to mitotane, which has low efficiency in advanced stages of the disease and is associated with high toxicity. Therefore, identification of new biological targets to improve ACC treatment is crucial. Blockade of the Wnt/beta-catenin pathway decreased adrenal steroidogenesis and increased apoptosis of NCI-H295 human ACC cells, in vitro and in a xenograft mouse model. Aurora kinases play important roles in cell division during the G1-M phase and their aberrant expression is correlated with a poor prognosis in different types of tumors. Hence, we hypothesized that inhibition of aurora kinases activity combined with the beta-catenin pathway blockade would improve the impairment of ACC cell growth in vitro. We studied the combinatorial effects of AMG 900, an aurora kinase inhibitor and PNU-74654, a beta-catenin pathway blocker, on proliferation, survival and tumor progression in multiple ACC cell lines: NCI-H295, CU-ACC1 and CU-ACC2. Exposure of ACC cells to the combination of AMG 900 with PNU-74654 decreased cell proliferation and viability compared to either treatment alone. In addition, AMG 900 inhibited cell invasion and clonogenesis compared to PNU-74654, and the combination showed no greater effects. In contrast, PNU-74654 was more effective in decreasing cortisol secretion. These data suggest that inhibition of aurora kinases activity combined with blockade of the beta-catenin pathway may provide a combinatorial approach for targeting ACC tumors.

New Prognostic Indicators in Pediatric Adrenal Tumors: Neuroblastoma and Adrenal Cortical Tumors, Can We Predict When These Will Behave Badly?

Pediatric adrenal tumors are unique entities with specific diagnostic, prognostic, and therapeutic challenges. The adrenal medulla gives rise to peripheral neuroblastic tumors (pNTs), pathologically defined by their architecture, stromal content, degree of differentiation, and mitotic-karyorrhectic index. Successful risk stratification of pNTs uses patient age, stage, tumor histology, and molecular/genetic aberrations. The adrenal cortex gives rise to adrenocortical tumors (ACTs), which present diagnostic and prognostic challenges. Histologic features that signify poor prognosis in adults can be meaningless in children, who have superior outcomes. The key clinical, pathologic, and molecular findings of pediatric ACTs have yet to be completely identified.

Targeted Disruption of Lats1 and Lats2 in Mice Impairs Adrenal Cortex Development and Alters Adrenocortical Cell Fate

It has recently been shown that the loss of the Hippo signaling effectors Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) in adrenocortical steroidogenic cells impairs the postnatal maintenance of the adrenal gland. To further explore the role of Hippo signaling in mouse adrenocortical cells, we conditionally deleted the key Hippo kinases large tumor suppressor homolog kinases 1 and -2 (Lats1 and Lats2, two kinases that antagonize YAP and TAZ transcriptional co-regulatory activity) in steroidogenic cells using an Nr5a1-cre strain (Lats1flox/flox;Lats2flox/flox;Nr5a1-cre). We report here that developing adrenocortical cells adopt characteristics of myofibroblasts in both male and female Lats1flox/flox;Lats2flox/flox;Nr5a1-cre mice, resulting in a loss of steroidogenic gene expression, adrenal failure and death by 2 to 3 weeks of age. A marked accumulation of YAP and TAZ in the nuclei of the myofibroblast-like cell population with an accompanying increase in the expression of their transcriptional target genes in the adrenal glands of Lats1flox/flox;Lats2flox/flox;Nr5a1-cre animals suggested that the myofibroblastic differentiation could be attributed in part to YAP and TAZ. Taken together, our results suggest that Hippo signaling is required to maintain proper adrenocortical cell differentiation and suppresses their differentiation into myofibroblast-like cells.

The prognostic value of YAP1 on clinical outcomes in human cancers

Background: As an important downstream factor in the Hippo pathway, yes-associated protein 1(YAP1) has been detected to be elevated in various cancers and demonstrated to play a role in tumor development. Therefore, we evaluated by a meta-analysis the prognostic value of YAP1 in cancer patients.

Results: Sixty-eight studies with 8631 patients were identified. The results indicated that YAP1 overexpression predicted unfavorable patient prognosis in studies with overall survival (OS) (HR=1.76, 95%CI: 1.50-2.06, p<0.001) and disease-free survival (DFS) (HR=1.39, 95%CI: 1.22-1.59, p<0.001), as well as in studies with recurrence-free survival (RFS) (HR=2.38, 95%CI: 1.73-3.27, p<0.001), and disease-specific survival (DSS) (HR=2.04, 95%CI: 1.55-2.70, p<0.001). Meanwhile, YAP1 overexpression was also observed to be significantly associated with worse OS in GEPIA (HR=1.2, p<0.001).

Conclusions: Overexpression of YAP1 showed great association with poorer prognosis in patients with various cancers, particularly liver cancer. Therefore, YAP1 might be an important prognostic marker and a novel target of cancer therapy.

Methods: We searched for potential publications in several online databases and retrieved relevant data. Overall and subgroup analyses were performed. Begg’s and Egger’s tests were used to assess publication bias. Online dataset GEPIA was used to generate the survival curves and verify the prognostic role of YAP1 in patients with tumors.

Challenges in surgical pathology of adrenocortical tumours

Adrenocortical carcinomas are rare tumours that can be diagnostically challenging. Numerous multiparametric scoring systems and diagnostic algorithms have been proposed to differentiate adrenocortical adenoma from adrenocortical carcinoma. Adrenocortical neoplasms must also be differentiated from other primary adrenal tumours, such as phaeochromocytoma and unusual primary adrenal tumours, as well as metastases to the adrenal gland. Myxoid, oncocytic and sarcomatoid variants of adrenocortical tumours must be recognized so that they are not confused with other tumours. The diagnostic criteria for oncocytic adrenocortical carcinoma are different from those for conventional adrenocortical carcinomas. Adrenocortical neoplasms in children are particularly challenging to diagnose, as histological features of malignancy in adrenocortical neoplasms in adults may not be associated with aggressive disease in the tumours of children. Recent histological and immunohistochemical studies and more comprehensive and integrated genomic characterizations continue to advance our understanding of the tumorigenesis of these aggressive neoplasms, and may provide additional diagnostic and prognostic utility and guide the development of therapeutic targets.

Hippo pathway affects survival of cancer patients: extensive analysis of TCGA data and review of literature

The disruption of the Hippo pathway occurs in many cancer types and is associated with cancer progression. Herein, we investigated the impact of 32 Hippo genes on overall survival (OS) of cancer patients, by both analysing data from The Cancer Genome Atlas (TCGA) and reviewing the related literature. mRNA and protein expression data of all solid tumors except pure sarcomas were downloaded from TCGA database. Thirty-two Hippo genes were considered; for each gene, patients were dichotomized based on median expression value. Survival analyses were performed to identify independent predictors, taking into account the main clinical-pathological features affecting OS. Finally, independent predictors were correlated with YAP1 oncoprotein expression. At least one of the Hippo genes is an independent prognostic factor in 12 out of 13 considered tumor datasets. mRNA levels of the independent predictors coherently correlate with YAP1 in glioma, kidney renal clear cell, head and neck, and bladder cancer. Moreover, literature data revealed the association between YAP1 levels and OS in gastric, colorectal, hepatocellular, pancreatic, and lung cancer. Herein, we identified cancers in which Hippo pathway affects OS; these cancers should be candidates for YAP1 inhibitors development and testing.

Targeted Disruption of YAP and TAZ Impairs the Maintenance of the Adrenal Cortex

Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) are functionally redundant transcriptional regulators that are downstream effectors of the Hippo signaling pathway. They act as major regulators of stem cell maintenance, cell growth, and differentiation. To characterize their roles in the adrenal cortex, we generated a mouse model in which Yap and Taz were conditionally deleted in steroidogenic cells (Yapflox/flox;Tazflox/flox;Nr5a1cre/+). Male Yapflox/flox;Tazflox/flox;Nr5a1cre/+ mice were characterized by an age-dependent degeneration of the adrenal cortex associated with an increase in apoptosis and a progressive reduction in the expression levels of steroidogenic genes. Evaluation of the expression levels of stem and progenitor cell population markers in the adrenal glands of Yapflox/flox;Tazflox/flox;Nr5a1cre/+ mice also showed the downregulation of sonic hedgehog (Shh), a marker of the subcapsular progenitor cell population. Gross degenerative changes were not observed in the adrenal glands of Yapflox/flox;Tazflox/flox;Nr5a1cre/+ females, although steroidogenic capacity and Shh expression were reduced, suggesting that mechanisms of adrenocortical maintenance are sex specific. These results define a crucial role for YAP and TAZ in the maintenance of the postnatal adrenal cortex.