Silencing mutated β-catenin inhibits cell proliferation and stimulates apoptosis in the adrenocortical cancer cell line H295R

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.

A reappraisal of transcriptional regulation by NR5A1 and beta-catenin in adrenocortical carcinoma

Background

Overexpression of the transcription factor NR5A1 and constitutive activation of canonical Wnt signalling leading to nuclear translocation of beta-catenin are hallmarks of malignancy in adrenocortical carcinoma (ACC). Based on the analysis of genomic profiles in H295R ACC cells, Mohan et al. (Cancer Res. 2023; 83: 2123-2141) recently suggested that a major determinant driving proliferation and differentiation in malignant ACC is the interaction of NR5A1 and beta-catenin on chromatin to regulate gene expression.

Methods

I reanalyzed the same set of data generated by Mohan et al. and other published data of knockdown-validated NR5A1 and beta-catenin target genes.

Results

Beta-catenin is mainly found in association to canonical T cell factor/lymphoid enhancer factor (TCF/LEF) motifs in genomic DNA. NR5A1 and beta-catenin regulate distinct target gene sets in ACC cells.

Conclusion

Overall, my analysis suggests a model where NR5A1 overexpression and beta-catenin activation principally act independently, rather than functionally interacting, to drive ACC malignancy.

Advances in translational research of the rare cancer type adrenocortical carcinoma

Adrenocortical carcinoma is a rare malignancy with an annual worldwide incidence of 1-2 cases per 1 million and a 5-year survival rate of <60%. Although adrenocortical carcinoma is rare, such rare cancers account for approximately one third of patients diagnosed with cancer annually. In the past decade, there have been considerable advances in understanding the molecular basis of adrenocortical carcinoma. The genetic events associated with adrenocortical carcinoma in adults are distinct from those of paediatric cases, which are often associated with germline or somatic TP53 mutations and have a better prognosis. In adult primary adrenocortical carcinoma, the main somatic genetic alterations occur in genes that encode proteins involved in the WNT-β-catenin pathway, cell cycle and p53 apoptosis pathway, chromatin remodelling and telomere maintenance pathway, cAMP-protein kinase A (PKA) pathway or DNA transcription and RNA translation pathways. Recently, integrated molecular studies of adrenocortical carcinomas, which have characterized somatic mutations and the methylome as well as gene and microRNA expression profiles, have led to a molecular classification of these tumours that can predict prognosis and have helped to identify new therapeutic targets. In this Review, we summarize these recent translational research advances in adrenocortical carcinoma, which it is hoped could lead to improved patient diagnosis, treatment and outcome.

Targeting Oncogenic Wnt/β-Catenin Signaling in Adrenocortical Carcinoma Disrupts ECM Expression and Impairs Tumor Growth

Adrenocortical carcinoma (ACC) is a rare but highly aggressive cancer with limited treatment options and poor survival for patients with advanced disease. An improved understanding of the transcriptional programs engaged in ACC will help direct rational, targeted therapies. Whereas activating mutations in Wnt/β-catenin signaling are frequently observed, the β-catenin-dependent transcriptional targets that promote tumor progression are poorly understood. To address this question, we analyzed ACC transcriptome data and identified a novel Wnt/β-catenin-associated signature in ACC enriched for the extracellular matrix (ECM) and predictive of poor survival. This suggested an oncogenic role for Wnt/β-catenin in regulating the ACC microenvironment. We further investigated the minor fibrillar collagen, collagen XI alpha 1 (COL11A1), and found that COL11A1 expression originates specifically from cancer cells and is strongly correlated with both Wnt/β-catenin activation and poor patient survival. Inhibition of constitutively active Wnt/β-catenin signaling in the human ACC cell line, NCI-H295R, significantly reduced the expression of COL11A1 and other ECM components and decreased cancer cell viability. To investigate the preclinical potential of Wnt/β-catenin inhibition in the adrenal microenvironment, we developed a minimally invasive orthotopic xenograft model of ACC and demonstrated that treatment with the newly developed Wnt/β-catenin:TBL1 inhibitor Tegavivint significantly reduced tumor growth. Together, our data support that the inhibition of aberrantly active Wnt/β-catenin disrupts transcriptional reprogramming of the microenvironment and reduces ACC growth and survival. Furthermore, this β-catenin-dependent oncogenic program can be therapeutically targeted with a newly developed Wnt/β-catenin inhibitor. These results show promise for the further clinical development of Wnt/β-catenin inhibitors in ACC and unveil a novel Wnt/β-catenin-regulated transcriptome.

Preclinical Models of Adrenocortical Cancer

Adrenocortical cancer is an aggressive endocrine malignancy with an incidence of 0.72 to 1.02 per million people/year, and a very poor prognosis with a five-year survival rate of 22%. As an orphan disease, clinical data are scarce, meaning that drug development and mechanistic research depend especially on preclinical models. While a single human ACC cell line was available for the last three decades, over the last five years, many new in vitro and in vivo preclinical models have been generated. Herein, we review both in vitro (cell lines, spheroids, and organoids) and in vivo (xenograft and genetically engineered mouse) models. Striking leaps have been made in terms of the preclinical models of ACC, and there are now several modern models available publicly and in repositories for research in this area.

Hereditary Endocrine Tumor Registries

Context

Endocrine neoplasia syndromes are phenotypically complex, and there is a misconception that they are universally rare. Genetic alterations are increasingly recognized; however, true prevalence is unknown. The purpose of a clinical registry is to monitor the quality of health care delivered to a specified group of patients through the collection, analysis, and reporting of relevant health-related information. This leads to improved clinical practice, decision-making, patient satisfaction, and outcome.

Objective

This review aims to identify, compare, and contrast active registries worldwide that capture data relevant to hereditary endocrine tumors (HETs).

Methods

Clinical registries were identified using a systematic approach from publications (Ovid MEDLINE, EMBASE) peer consultation, clinical trials, and web searches. Inclusion criteria were hereditary endocrine tumors, clinical registries, and English language. Exclusion criteria were institutional audits, absence of clinical data, or inactivity. Details surrounding general characteristics, funding, data fields, collection periods, and entry methods were collated.

Results

Fifteen registries specific for HET were shortlisted with 136 affiliated peer-reviewed manuscripts.

Conclusion

There are few clinical registries specific to HET. Most of these are European, and the data collected are highly variable. Further research into their effectiveness is warranted. We note the absence of an Australian registry for all HET, which would provide potential health and economic gains. This review presents a unique opportunity to harmonize registry data for HET locally and further afield.

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.

Preclinical assessment of synergistic efficacy of MELK and CDK inhibitors in adrenocortical cancer

BACKGROUND

Adrenocortical cancer (ACC) is a rare and aggressive cancer with dismal 5-year survival due to a lack of effective treatments. We aimed to identify a new effective combination of drugs and investigated their synergistic efficacy in ACC preclinical models.

METHODS

A quantitative high-throughput drug screening of 4,991 compounds was performed on two ACC cell lines, SW13 and NCI-H295R, based on antiproliferative effect and caspase-3/7 activity. The top candidate drugs were pairwise combined to identify the most potent combinations. The synergistic efficacy of the selected inhibitors was tested on tumorigenic phenotypes, such as cell proliferation, migration, invasion, spheroid formation, and clonogenicity, with appropriate mechanistic validation by cell cycle and apoptotic assays and protein expression of the involved molecules. We tested the efficacy of the drug combination in mice with luciferase-tagged human ACC xenografts. To study the mRNA expression of target molecules in ACC and their clinical correlations, we analyzed the Gene Expression Omnibus and The Cancer Genome Atlas.

RESULTS

We chose the maternal embryonic leucine zipper kinase (MELK) inhibitor (OTS167) and cyclin-dependent kinase (CDK) inhibitor (RGB-286638) because of their potent synergy from the pairwise drug combination matrices derived from the top 30 single drugs. Multiple publicly available databases demonstrated overexpression of MELK, CDK1/2, and partnering cyclins mRNA in ACC, which were independently associated with mortality and other adverse clinical features. The drug combination demonstrated a synergistic antiproliferative effect on ACC cells. Compared to the single-agent treatment groups, the combination treatment increased G2/M arrest, caspase-dependent apoptosis, reduced cyclins A2, B1, B2, and E2 expression, and decreased cell migration and invasion with reduced vimentin. Moreover, the combination effectively decreased Foxhead Box M1, Axin2, glycogen synthase kinase 3-beta, and β-catenin. A reduction in p-stathmin from the combination treatment destabilized microtubule assembly by tubulin depolymerization. The drug combination treatment in mice with human ACC xenografts resulted in a significantly lower tumor burden than those treated with single-agents and vehicle control groups.

CONCLUSIONS

Our preclinical study revealed a novel synergistic combination of OTS167 and RGB-286638 in ACC that effectively targets multiple molecules associated with ACC aggressiveness. A phase Ib/II clinical trial in patients with advanced ACC is therefore warranted.

Pediatric adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is a rare endocrine malignancy of the adrenal gland with an unfavorable prognosis. It is rare in the pediatric population, with an incidence of 0.2-0.3 patients per million in patients under 20 years old. It is primarily associated with Li-Fraumeni and Beckwith-Wiedemann tumor predisposition syndromes in children. The incidence of pediatric ACC is 10-15fold higher in southern Brazil due to a higher prevalence of TP53 mutation associated with Li-Fraumeni syndrome in that population. Current treatment protocols are derived from adult ACC and consist of surgery and/or chemotherapy with etoposide, doxorubicin, and cisplatin (EDP) with mitotane. Limited research has been reported on other treatment modalities for pediatric ACC, including mitotane, pembrolizumab, cabozantinib, and chimeric antigen receptor autologous cell (CAR-T) therapy.

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.

Tumor Microenvironment in Adrenocortical Carcinoma: Barrier to Immunotherapy Success?

Adrenocortical carcinoma is a rare malignancy with aggressive behavior, with up to 40% of patients presenting with metastases at the time of diagnosis. Both conventional chemotherapeutic regimens and novel immunotherapeutic agents, many of which are currently being tested in ongoing clinical trials, have yielded modest results so far, bringing the need for a deeper understanding of adrenal cancer behavior to the forefront. In the recent years, the tumor microenvironment has emerged as a major determinant of cancer response to immunotherapy and an increasing number of studies on other solid tumors have focused on manipulating the microenvironment in the favor of the host and discovering new potential target molecules. In the present review we aim to explore the characteristics of adrenocortical cancer's microenvironment, highlighting the mechanisms of immune evasion responsible for the modest immunotherapeutic results, and identify novel potential strategies.

Plant Natural Compounds in the Treatment of Adrenocortical Tumors

Plant natural products are a plethora of diverse and complex molecules produced by the plant secondary metabolism. Among these, many can reserve beneficial or curative properties when employed to treat human diseases. Even in cancer, they can be successfully used and indeed numerous phytochemicals exert antineoplastic activity. The most common molecules derived from plants and used in the fight against cancer are polyphenols, i.e., quercetin, genistein, resveratrol, curcumin, etc. Despite valuable data especially in preclinical models on such compounds, few of them are currently used in the medical practice. Also, in adrenocortical tumors (ACT), phytochemicals are scarcely or not at all used. This work summarizes the available research on phytochemicals used against ACT and adrenocortical cancer, a very rare disease with poor prognosis and high metastatic potential, and wants to contribute to stimulate preclinical and clinical research to find new therapeutic strategies among the overabundance of biomolecules produced by the plant kingdom.

The effects of mitotane and 1α,25-dihydroxyvitamin D3 on Wnt/beta-catenin signaling in human adrenocortical carcinoma cells

PURPOSE

Mitotane is the only chemotherapeutic agent available for the treatment of adrenocortical carcinoma (ACC), however, the anti-neoplastic efficacy is limited due to several side-effects in vivo. There is, therefore, a need of exploring for new anti-tumoral agents which can be used either alone or in combination with mitotane. The active vitamin D metabolite 1α,25-dihydroxyvitamin D₃ (1α,25(OH)₂D₃) acts as an anti-proliferative agent in human cancer by inhibiting the Wnt/beta-catenin pathway through the vitamin D receptor (VDR). The aim of this study was to study the effects of mitotane and 1α,25(OH)₂D₃, individually or in combination, in an in vitro model with H295R ACC cells, and to elucidate the molecular events behind their effects involving the Wnt/beta-catenin signaling.

METHODS AND RESULTS

Multiple concentrations of mitotane and 1α,25(OH)₂D₃, individually or in combination, were tested on H295R cells for 24-96 h, and the effects analysed by MTT. A reduction in cell growth was observed in a dose/time-dependent manner for both mitotane and 1α,25(OH)₂D₃. In addition, a combination of clinically sub-therapeutic concentrations of mitotane with 1α,25(OH)₂D₃, had an additive anti-proliferative effect (Combination Index = 1.02). In a wound healing assay, individual treatments of both mitotane and 1α,25(OH)₂D₃ reduced the migration ability of H295R cells, with the effect further enhanced on combining both the agents. Western blotting and qRT-PCR analysis showed a modulation of the Wnt/beta-catenin and VDR signaling pathways.

CONCLUSION

Our results show an additive effect of mitotane and 1α,25(OH)₂D₃ on the inhibition of H295R ACC cell growth and viability, and suggest that molecular mechanisms of their effects involve a functional link between VDR and Wnt/beta-catenin pathways.

Effects of Adipocyte-derived Factors on the Adrenal Cortex

Background and Objective:

Obesity is highly complicated by hypertension and hyperglycemia. In particular, it has been proposed that obesity-related hypertension is caused by adipocyte-derived factors that are recognized as undetermined proteins secreted from adipocytes. Adipocyte-derived factors have been known to be related to aldosterone secretion in the adrenal gland. So far, Wnt proteins, CTRP-1, VLDL, LDL, HDL and leptin have been demonstrated to stimulate aldosterone secretion. In contrast, it has not yet been clarified whether adipocyte-derived factors also affect adrenal cortisol secretion.

Methods and Results:

In the present study, we investigated the effect of adipocyte-derived factors on cortisol synthase gene CYP11B1 mRNA expression in vitro study using adrenocortical carcinoma H295R cells and mouse fibroblast 3T3-L1cells. Interestingly, adipocyte-derived factors were demonstrated to have the ability to stimulate CYP11B1 mRNA expression.

Conclusion:

Since CYP11B1 is well known as a limiting enzyme of cortisol synthesis, our study suggests that adipocyte-derived factors may stimulate cortisol secretion, as well as aldosterone secretion. Taken together, adipocyte-derived factors may be the cause of metabolic syndrome due to their stimulating effects on aldosterone/cortisol secretion. Therefore, the innovation of novel drugs against them may possibly be a new approach against metabolic syndrome.

CTNNB1 Knockdown Inhibits Cell Proliferation and Aldosterone Secretion Through Inhibiting Wnt/β-Catenin Signaling in H295R Cells

Aldosterone-producing adenomas (APA) is one of the causative factors of primary aldosteronism. Previous studies have suggested that there are somatic CTNNB1 mutations in APA, but the specific mechanism of CTNNB1 mutation in APA tumorigenesis and aldosterone secretion remains unclear. In the present study, human adrenocortical carcinoma cell line H295 R was used to establish stable CTNNB1 knockdown cell lines. Cell proliferation and aldosterone secretion of H295 R cells in response to angiotensin Ⅱ (Agn Ⅱ) were analyzed. We found that CTNNB1 knockdown reduced β-catenin expression and inhibited proliferation of H295 R cells. CTNNB1 knockdown inhibited Wnt/β-catenin signaling pathway and downregulated expression of downstream genes including axin 2, lymphoid enhancer binding factor 1 (LEF1), and cyclin D1. In addition, CTNNB1 knockdown decreased responses of H295 R cells to Agn Ⅱ and decreased aldosterone secretion. Our findings suggest that CTNNB1 knockdown can inhibit H295 R cell proliferation and decrease aldosterone secretion in the responses of H295 R cells to Ang II through inhibiting Wnt/β-catenin signaling pathway, indicating that targeting Wnt/β-catenin signaling pathway may be an important approach to decrease aldosterone secretion in the treatment of aldoster-producing adenomas.

Contemporary preclinical human models of adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is an uncommon and heterogeneous disease and may present differently in children and adults. Management of ACC is dependent on disease stage and complete surgical resection is the only potentially curative treatment. The first and most extensively used adrenocortical cancer cell line, as model system to examine mechanisms controlling normal and pathologic function of adrenal cortex, was initially isolated in 1980. Although NCI-H295 maintained steroid capabilities and adrenocortical characteristics, the lack of new cell lines and animal models of ACC has hampered the progress and development of new therapies. In this review we provide description of cellular and patient-derived tumor xenograft (PDTX) models of ACC generated for the elucidation of the underlying pathogenic mechanisms and preclinical functional studies for this aggressive disease.

Therapeutic Targets for Adrenocortical Carcinoma in the Genomics Era

Adrenocortical carcinoma (ACC) is a rare and often fatal cancer, affecting ~1 person per million per year worldwide. Approximately 75% of patients with ACC eventually develop metastases and progress on the few available standard-of-care medical therapies, highlighting an incredible need for an improved understanding of the molecular biology of this disease. Although it has long been known that ACC is characterized by certain histological and genetic features (e.g., high mitotic activity, chromosomal instability, and overexpression of IGF2), only in the last two decades of genomics has the molecular landscape of ACC been more thoroughly characterized. In this review, we describe the findings of historical genetics and recent genomics studies on ACC and discuss how underlying concepts emerging from these studies contribute to the current model of critical pathways for adrenocortical carcinogenesis. Integrative synthesis across these studies reveals that ACC consists of three distinct molecular subtypes with divergent clinical outcomes and implicates differential regulation of Wnt signaling, cell cycle, DNA methylation, immune biology, and steroidogenesis in ACC biology. These cellular programs are pharmacologically targetable and may enable the development of therapeutic strategies to improve outcomes for patients facing this devastating disease.

Development of new preclinical models to advance adrenocortical carcinoma research

Adrenocortical cancer (ACC) is an orphan malignancy that results in heterogeneous clinical phenotypes and molecular genotypes. There are no curative treatments for this deadly cancer with 35% survival at five years. Our understanding of the underlying pathobiology and our ability to test novel therapeutic targets has been limited due to the lack of preclinical models. Here, we report the establishment of two new ACC cell lines and corresponding patient-derived xenograft (PDX) models. CU-ACC1 cell line and PDX were derived from a perinephric metastasis in a patient whose primary tumor secreted aldosterone. CU-ACC2 cell line and PDX were derived from a liver metastasis in a patient with Lynch syndrome. Short tandem repeat profiling confirmed consistent matches between human samples and models. Both exomic and RNA sequencing profiling were performed on the patient samples and the models, and hormonal secretion was evaluated in the new cell lines. RNA sequencing and immunohistochemistry confirmed the expression of adrenal cortex markers in the PDXs and human tumors. The new cell lines replicate two of the known genetic models of ACC. CU-ACC1 cells had a mutation in CTNNB1 and secreted cortisol but not aldosterone. CU-ACC2 cells had a TP53 mutation and loss of MSH2 consistent with the patient's known germline mutation causing Lynch syndrome. Both cell lines can be transfected and transduced with similar growth rates. These new preclinical models of ACC significantly advance the field by allowing investigation of underlying molecular mechanisms of ACC and the ability to test patient-specific therapeutic targets.

Targeting heterogeneity of adrenocortical carcinoma: Evaluation and extension of preclinical tumor models to improve clinical translation

In recent years it has been recognized that clinical translation of novel therapeutic strategies for patients with adrenocortical carcinoma (ACC) often fails. These disappointing results indicate that the currently utilized tumor models only poorly reflect relevant pathophysiology and, thereby, do not predict clinical applicability of novel pharmacological approaches. However, also the development of new preclinical ACC models has remained a challenge with only one human cell line (NCI-H295R) and one recently established human pediatric xenograft model (SJ-ACC3) being available for this highly heterogeneous malignancy. Our current study furthermore reveals a poor reproducibility of therapeutic action between different clones of the most commonly used tumor model NCI-H295R. In an attempt to broaden the current preclinical armamentarium, we aimed at the development of patient-individual tumor models. During these studies, one xenograft (MUC-1) displayed marked engraftment and sustained tumor growth. MUC-1 tumor analysis revealed highly vascularized, proliferating and SF-1 positive xenografts. In a next step, we characterized all currently available human tumor models for ACC for Ki67, SF-1 and EGF-receptor status in comparison with MUC-1-xenografts. In addition, we established a primary culture, which is now viable over 31 passages with sustained nuclear SF-1 and cytoplasmic 3βHSD immuno-positivity. Subsequent investigation of therapeutic responsiveness upon treatment with the current systemic gold standard EDP-M (etoposide, doxorubicin, cisplatin and mitotane) demonstrated maintenance of the clinically observed drug resistance for MUC-1 exclusively. In summary, we provide evidence for a novel patient-derived tumor model with the potential to improve clinical prediction of novel therapeutic strategies for patients with ACC.

The next step: mechanisms driving adrenocortical carcinoma metastasis

Endocrine tumors have the peculiarity to become clinically evident not only due to symptoms related to space occupation by the growing lesion, similarly to most other tumors, but also, and most often, because of their specific hormonal secretion, which significantly contributes to their pathological burden. Malignant endocrine tumors, in addition, have the ability to produce distant metastases. Here, we critically review the current knowledge about mechanisms and biomarkers characterizing the metastatic process in adrenocortical carcinoma (ACC), a rare endocrine malignancy with a high risk of relapse and metastatization even when the primary tumor is diagnosed and surgically removed at an early stage. We highlight perspectives of future research in the domain and possible new therapeutic avenues based on targeting factors having an important role in the metastatic process of ACC.

Case report: primary acinar cell carcinoma of the liver treated with multimodality therapy

We describe a case of primary acinar cell carcinoma (ACC) originating in the liver in a 54-year-old female, diagnosed following persistent abnormal elevated liver function. Imaging revealed two masses, one dominant lesion in the right hepatic lobe and another in segment IVA. A right hepatectomy was performed to remove the larger lesion, while the mass in segment IVA was unresectable due to its proximity to the left hepatic vein. Immunohistochemical staining showed positivity for trypsin and chymotrypsin. Postoperatively the patient underwent hepatic arterial embolization of the other unresectable lesion followed by FOLFOX chemotherapy. At 20 months from diagnosis the patient is currently under observation with a decreasing necrotic mass and no other disease evident. Based on histology, immunohistochemistry and radiological findings a diagnosis of primary ACC of the liver was made. Genomic assessment of somatic mutations within the patient's tumor was also performed through next generation sequencing and findings were consistent with an acinar malignancy. This case highlights a rare tumor subtype treated with a combination of therapeutic modalities through a multidisciplinary approach.

Curcumin inhibits bladder cancer progression via regulation of β-catenin expression

Bladder cancer has a considerable morbidity and mortality impact with particularly poor prognosis. Curcumin has been recently noticed as a polyphenolic compound separated from turmeric to regulate tumor progression. However, the precise molecular mechanism by which curcumin inhibits the invasion and metastasis of bladder cancer cells is not fully elucidated. In this study, we investigate the effect of curcumin on the bladder cancer as well as possible mechanisms of curcumin. The expression of β-catenin was detected by quantitative real-time polymerase chain reaction and immunohistochemical analysis in a series of bladder cancer tissues. In addition, bladder cancer cell lines T24 and 5637 cells were treated with different concentrations of curcumin. The cytotoxic effect of curcumin on cell proliferation of T24 and 5637 cells was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The migration and invasion capacity of T24 and 5637 cells were measured by transwell assay. The effects of curcumin on expression levels of β-catenin and epithelial-mesenchymal transition marker were determined by western blotting. The β-catenin expression was significantly upregulated in bladder cancer tissues when compared with corresponding peri-tumor tissues. Furthermore, curcumin inhibited the cell proliferation of T24 and 5637 cells, and curcumin reduced the migration and invasive ability of T24 and 5637 cells via regulating β-catenin expression and reversing epithelial-mesenchymal transition. Curcumin may be a new drug for bladder cancer.

Cell signaling pathways in the adrenal cortex: Links to stem/progenitor biology and neoplasia

The adrenal cortex is a dynamic tissue responsible for the synthesis of steroid hormones, including mineralocorticoids, glucocorticoids, and androgens in humans. Advances have been made in understanding the role of adrenocortical stem/progenitor cell populations in cortex homeostasis and self-renewal. Recently, large molecular profiling studies of adrenocortical carcinoma (ACC) have given insights into proteins and signaling pathways involved in normal tissue homeostasis that become dysregulated in cancer. These data provide an impetus to examine the cellular pathways implicated in adrenocortical disease and study connections, or lack thereof, between adrenal homeostasis and tumorigenesis, with a particular focus on stem and progenitor cell pathways. In this review, we discuss evidence for stem/progenitor cells in the adrenal cortex, proteins and signaling pathways that may regulate these cells, and the role these proteins play in pathologic and neoplastic conditions. In turn, we also examine common perturbations in adrenocortical tumors (ACT) and how these proteins and pathways may be involved in adrenal homeostasis.

New insights and future perspectives in the therapeutic strategy of adrenocortical carcinoma (Review)

Adrenocortical carcinoma (ACC) is a rare endocrine malignancy with an incidence ranging from 0.7 to 2.0 cases/million people per year. Hypercortisolism represents the most common clinical presentation in many patients although, less frequently, some ACC secreting androgens and estrogens are even more pathognomonic compared to cortisol secretion. Currently, radical surgery, when feasible, is still the only curative therapy. Mitotane, an adrenolytic drug, is used in the adjuvant setting and in combination with chemotherapy drugs in metastatic disease. The use of radiotherapy remains controversial, being indicated only in selected cases. New targeted therapies, such as insulin growth factor-1 (IGF-1), mammalian-target of rapamycin (m-TOR), vascular endothelial growth factor (VEGF) inhibitors and others, have recently been investigated with disappointing clinical results. The partial effectiveness of current treatments mandates the need for new therapeutic strategies against this tumor.

Liposomal doxorubicin for active targeting: surface modification of the nanocarrier evaluated in vitro and in vivo: challenges and prospects

Due to the inability of classical chemotherapeutic agents to exclusively target tumor cells, these treatments are associated with severe toxicity profiles. Thus, long-circulating liposomes have been developed in the past to enhance accumulation in tumor tissue by passive targeting. Accordingly, commercially available liposomal formulations of sterically stabilized liposomal doxorubicin (Caelyx^®, Doxil^®, Lipodox^®) are associated with improved off-target profiles. However, these preparations are still not capable to selectively bind to target cells. Thus, in an attempt to further optimize existing treatment schemes immunoliposomes have been established to enable active targeting of tumor tissues. Recently, we have provided evidence for therapeutic efficacy of anti-IGF1R-targeted, surface modified doxorubicin loaded liposomes. Our approach involved a technique, which allows specific post-modifications of the liposomal surface by primed antibody-anchor conjugates thereby facilitating personalized approaches of commercially available liposomal drugs. In the current study, post-modification of sterically stabilized liposomal Dox was thoroughly investigated including the influence of different modification techniques (PIT, SPIT, SPIT60), lipid composition (SPC/Chol, HSPC/Chol), and buffers (HBS, SH). As earlier in vivo experiments did not take into account the presence of non-integrated ab-anchor conjugates this was included in the present study. Our experiments provide evidence that post-modification of commercially available liposomal preparations for active targeting is possible. Moreover, lyophilisation represents an applicable method to obtain a storable precursor of surface modifying antibody-anchor conjugates. Thus, these findings open up new approaches in patient individualized targeting of chemotherapeutic therapies.

Inhibition of the Tcf/beta-catenin complex increases apoptosis and impairs adrenocortical tumor cell proliferation and adrenal steroidogenesis

Background

To date, there is no effective therapy for patients with advanced/metastatic adrenocortical cancer (ACC). The activation of the Wnt/beta-catenin signaling is frequent in ACC and this pathway is a promising therapeutic target.

Aim

To investigate the effects of the inhibition of the Wnt/beta-catenin in ACC cells.

Methods

Adrenal (NCI-H295 and Y1) and non-adrenal (HeLa) cell lines were treated with PNU-74654 (5–200 μM) for 24–96 h to assess cell viability (MTS-based assay), apoptosis (Annexin V), expression/localization of beta-catenin (qPCR, immunofluorescence, immunocytochemistry and western blot), expression of beta-catenin target genes (qPCR and western blot), and adrenal steroidogenesis (radioimmunoassay, qPCR and western blot).

Results

In NCI-H295 cells, PNU-74654 significantly decreased cell proliferation 96 h after treatment, increased early and late apoptosis, decreased nuclear beta-catenin accumulation, impaired CTNNB1/beta-catenin expression and increased beta-catenin target genes 48 h after treatment. No effects were observed on HeLa cells. In NCI-H295 cells, PNU-74654 decreased cortisol, testosterone and androstenedione secretion 24 and 48 h after treatment. Additionally, in NCI-H295 cells, PNU-74654 decreased SF1 and CYP21A2 mRNA expression as well as the protein levels of STAR and aldosterone synthase 48 h after treatment. In Y1 cells, PNU-74654 impaired corticosterone secretion 24 h after treatment but did not decrease cell viability.

Conclusions

Blocking the Tcf/beta-catenin complex inhibits the Wnt/beta-catenin signaling in adrenocortical tumor cells triggering increased apoptosis, decreased cell viability and impairment of adrenal steroidogenesis. These promising findings pave the way for further experiments inhibiting the Wnt/beta-catenin pathway in pre-clinical models of ACC. The inhibition of this pathway may become a promising adjuvant therapy for patients with ACC.

Loss of β-catenin in adrenocortical cancer cells causes growth inhibition and reversal of epithelial-to-mesenchymal transition

Adrenal carcinoma (ACC) is a rare neoplasm with a poor outcome. Aberrant expression of β-catenin has been found in approximatively 30% of ACC. We herein studied its effects on the growth of the human ACC cell line H295R. The cells were infected with short hairpin RNA (shRNA)-mediated silencing β-catenin. Two shRNAs used induced down-regulation of β-catenin protein levels. The expression of these shRNAs decreased cell growth and increased H295R cells in S and G₂/M phases. This cytostatic effect is due to a decrease of phosphorylated MAPK and to an up-regulation expression of the cyclin-dependent kinase inhibitors p57^KIP2, p21^CIP and p27^KIP1. In addition, the knockdown of β-catenin decreased phosphorylated Akt and increased apoptosis. Finally, loss of β-catenin was sufficient to induce the reversal of the epithelial-to-mesenchymal transition. We then transplanted these genetically modified H295R cells in Scid mice. Tumor growth suppression was achieved by the two shRNAs showing in vitro efficacy. Proliferation was not reduced in silenced tumors. In contrast, p57, p27 and p21 proteins were found expressed at high levels in silenced tumors along with an increase in apoptotic cells. These findings indicate that β-catenin loss in H295R cells inhibits tumor growth by inducing transcriptional and functional changes.

Identification of Niclosamide as a Novel Anticancer Agent for Adrenocortical Carcinoma

PURPOSE

Adrenocortical carcinoma (ACC) is a rare and aggressive cancer, and no current effective therapy is available for locally advanced and metastatic ACC. Drug repurposing is an emerging approach for identifying new indications for existing drugs, especially for rare cancers such as ACC. The objective of this study was to use quantitative high-throughput screening to identify agents with antineoplastic activity against ACC.

EXPERIMENTAL DESIGN

A screening of 4,292 compounds was performed on three ACC cell lines: BD140A, SW-13, and NCI-H295R.

RESULTS

Twenty-one active compounds were identified, with an efficacy of >80% in all three cell lines. Of these, niclosamide showed higher efficacy and lower IC50 than established anti-ACC drugs. We then validated niclosamide-inhibited cellular proliferation in all three ACC cell lines. Next, we investigated the mechanism by which niclosamide inhibited ACC cell proliferation, and found that it induced caspase-dependent apoptosis and G1 cell-cycle arrest. Niclosamide also decreased cellular migration and reduced the level of mediators of epithelial-to-mesenchymal transition, such as N-cadherin and vimentin. Furthermore, niclosamide treatment resulted in decreased expression of β-catenin. We also evaluated the effect of niclosamide on energy metabolism in ACC cell lines and found it resulted in mitochondrial uncoupling. Niclosamide treatment inhibited ACC tumor growth with no observed toxicity in mice in vivo

CONCLUSIONS

Our findings suggest that niclosamide has anti-ACC activity through its inhibition of multiple altered cellular pathways and cellular metabolism in ACC. Our results provide a preclinical rationale for evaluating niclosamide therapy in a clinical trial for ACC. Clin Cancer Res; 22(14); 3458-66. ©2016 AACR.

Xenograft models for adrenocortical carcinoma

Adrenocortical carcinomas (ACCs) are rare, heterogeneous and very malignant endocrine tumors with a poor prognosis. An important prerequisite to optimize existing therapeutic regimens and to develop novel therapeutic strategies are preclinical disease models. In recent years molecular and genetic profiling of surgical tumor specimen led to the identification of novel interesting markers. However, precise involvement of these markers in tumorigenesis and their functional relevance in therapeutic outcome is still under investigation. Xenograft models are important tools for such functional studies as they bear the potential to mimic the complexity of solid tumors including tumor cells, stroma and blood vessels. Thus, for the successful and safe development of novel therapeutic strategies xenograft models remain to be indispensable experimental tools. Here we provide an overview on currently existing xenograft models for ACC, their tissue origins, establishment, implications as well as limitations.

5th International ACC Symposium: An Outlook to Current and Future Research on the Biology of Adrenocortical Carcinoma: Diagnostic and Therapeutic Applications

Groundbreaking progress has been recently made in elucidating the signaling pathways that are altered in adrenocortical carcinoma (ACC), an endocrine malignancy that still has an unfavorable prognosis, and in understanding its genomic structure. These advances need now to be translated to create cellular and animal models more relevant to human disease in order to develop new and more effective diagnostic procedures and targeted therapies against this deadly malignancy.

Combined transcriptome studies identify AFF3 as a mediator of the oncogenic effects of β-catenin in adrenocortical carcinoma

Adrenocortical cancer (ACC) is a very aggressive tumor, and genomics studies demonstrate that the most frequent alterations of driver genes in these cancers activate the Wnt/β-catenin signaling pathway. However, the adrenal-specific targets of oncogenic β-catenin-mediating tumorigenesis have not being established. A combined transcriptomic analysis from two series of human tumors and the human ACC cell line H295R harboring a spontaneous β-catenin activating mutation was done to identify the Wnt/β-catenin targets. Seven genes were consistently identified in the three studies. Among these genes, we found that AFF3 mediates the oncogenic effects of β-catenin in ACC. The Wnt response element site located at nucleotide position −1408 of the AFF3 transcriptional start sites (TSS) mediates the regulation by the Wnt/β-catenin signaling pathway. AFF3 silencing decreases cell proliferation and increases apoptosis in the ACC cell line H295R. AFF3 is located in nuclear speckles, which play an important role in RNA splicing. AFF3 overexpression in adrenocortical cells interferes with the organization and/or biogenesis of these nuclear speckles and alters the distribution of CDK9 and cyclin T1 such that they accumulate at the sites of AFF3/speckles. We demonstrate that AFF3 is a new target of Wnt/β-catenin pathway involved in ACC, acting on transcription and RNA splicing.

Effects and mechanism of miR-214 on hepatocellular carcinoma

OBJECTIVE

To explore the role of miR-214 in the progression of hepatocellular carcinoma (HCC) and its inhibitory mechanisms in depressing the signaling pathway of β-catenin, this study was conducted.

METHODS

We ectopically expressed miR-214 in HepG2 cells to obtain cell lines Lv-miR-214-HepG2 and their control Lv-control-HepG2. Differences between the two cell lines were compared in cell growth, proliferation, colony forming ability and cell cycles. RT-PCR method was applied for the quantification of β-catenin mRNA expression. Western-blot method was applied for the determination of the protein level of β-catenin and their downstream targets (ie. Cyclin D1, c-Myc and TCF-1). The effect of miR-214 on cells was further explored through RNA interference and restoring miR-214 expression.

RESULTS

In comparison with negative (Lv-control-HepG2) and blank (HepG2) control, a significant inhibition of cell growth and proliferation caused by miR-214 was observed after 48∼72h of cell culture experiments (P<0.05). The miR-214 treatment resulted in a colony forming efficiency of (23.28±3.26)%, which was significantly lower than that of negative control [(51.31±3.97)%] (P<0.05). According to FCM results, the experimental group, compared with control, showed a higher proportion of cells in G0/G1 phase [(70.32±3.12)%] but a lower proportion in S phase [(18.42±2.90)%] (P<0.05). The MTT assay demonstrated a significant inhibition of the proliferation and β-catenin expression of HCC cells compared with control (P<0.05), while no significant difference was observed after HCC cells being transfected with β-catenin overexpression plasmid (P>0.05). By comparing to the RT-PCR and Western-blot results of control, the miR-214 treatment led to a slightly decrease in the β-catenin mRNA expression (P>0.05), but an extremely inhibition in the protein level of β-catenin and its downstream targets Cyclin D1, c-Myc, and TCF-1 (P<0.05).

CONCLUSIONS

miR-214 functions as a suppressor during the progression of HCC, and its inhibitory role was achieved by down-regulating β-catenin signaling pathway.

Genomic and immunohistochemical analysis in human adrenal cortical neoplasia reveal beta-catenin mutations as potential prognostic biomarker

Evaluation for malignancy of the adrenal cortex, adrenal cortical carcinoma (ACC), is a challenge in surgical pathology due to its relative rarity and histologic overlap with its benign counterpart, adrenocortical adenoma (ACA). We characterized a cohort of human ACC and ACA, including a molecular screen, with a goal of identifying potential diagnostic adjuncts. Thirty-six cases of ACC underwent histologic and clinical review. In the 31 ACC cases with available material and a cohort of 10 ACA cases, a multiplex nucleotide amplification molecular screen from formalin-fixed, paraffin-embedded tissue was peformed. ACCs demonstrated a wide variety of clinical and histologic characteristics with overall poor but unpredictable survival for subjects with ACC. By mutational screen, 12/31 (38.7%) carcinomas harbored CTNNB1 mutations, 1 with an additional TP53 mutation; 1 case each had isolated APC and TP53 mutations; 16 were wild-type for all tested loci; and 1 case demonstrated repeated assay failures. Two of the 10 ACA (20%) demonstrated CTNNB1 mutations by mutational screen, with no additional mutations. Immunohistochemistry for beta-catenin was performed and compared with the results of the molecular screen. Strong nuclear beta-catenin immunopositivity corresponded to the presence of CTNNB1 mutation by genotyping in 10 of 12 cases (83% sensitivity); the mismatched case(s) demonstrated strong membranous staining by immunohistochemistry. Seventeen of the 18 cases without CTNNB1 mutation showed membranous staining or did not stain (94% specificity); the mismatched case demonstrated scattered (<10%) positive nuclei. Both mutations in ACA were corroborated with immunohistochemistry for beta-catenin. No histomorphologic parameter appeared dominant in lesions with a particular mutational status. Based on these results, mutational status of CTNNB1 in adrenal cortical neoplasms can be predicted with reasonable accuracy by immunohistochemical cellular localization. Nuclear localization of beta-catenin by immunostain may be helpful in analysis of select lesions of the adrenal cortex whose biological behavior is uncertain from clinical and histologic information; a larger cohort is required to test this hypothesis.

Adrenocortical growth and cancer

The adrenal gland consists of two distinct parts, the cortex and the medulla. Molecular mechanisms controlling differentiation and growth of the adrenal gland have been studied in detail using mouse models. Knowledge also came from investigations of genetic disorders altering adrenal development and/or function. During embryonic development, the adrenal cortex acquires a structural and functional zonation in which the adrenal cortex is divided into three different steroidogenic zones. Significant progress has been made in understanding adrenal zonation. Recent lineage tracing experiments have accumulated evidence for a centripetal differentiation of adrenocortical cells from the subcapsular area to the inner part of the adrenal cortex. Understanding of the mechanism of adrenocortical cancer (ACC) development was stimulated by knowledge of adrenal gland development. ACC is a rare cancer with a very poor overall prognosis. Abnormal activation of the Wnt/β-catenin as well as the IGF2 signaling plays an important role in ACC development. Studies examining rare genetic syndromes responsible for familial ACT have played an important role in identifying genetic alterations in these tumors (like TP53 or CTNNB1 mutations as well as IGF2 overexpression). Recently, genomic analyses of ACT have shown gene expression profiles associated with malignancy as well as chromosomal and methylation alterations in ACT and exome sequencing allowed to describe the mutational landscape of these tumors. This progress leads to a new classification of these tumors, opening new perspectives for the diagnosis and prognostication of ACT. This review summarizes current knowledge of adrenocortical development, growth, and tumorigenesis.

Wnt signaling inhibits adrenal steroidogenesis by cell-autonomous and non-cell-autonomous mechanisms

Wnt/β-catenin (βcat) signaling is critical for adrenal homeostasis. To elucidate how Wnt/βcat signaling elicits homeostatic maintenance of the adrenal cortex, we characterized the identity of the adrenocortical Wnt-responsive population. We find that Wnt-responsive cells consist of sonic hedgehog (Shh)-producing adrenocortical progenitors and differentiated, steroidogenic cells of the zona glomerulosa, but not the zona fasciculata and rarely cells that are actively proliferating. To determine potential direct inhibitory effects of βcat signaling on zona fasciculata-associated steroidogenesis, we used the mouse ATCL7 adrenocortical cell line that serves as a model system of glucocorticoid-producing fasciculata cells. Stimulation of βcat signaling caused decreased corticosterone release consistent with the observed reduced transcription of steroidogenic genes Cyp11a1, Cyp11b1, Star, and Mc2r. Decreased steroidogenic gene expression was correlated with diminished steroidogenic factor 1 (Sf1; Nr5a1) expression and occupancy on steroidogenic promoters. Additionally, βcat signaling suppressed the ability of Sf1 to transactivate steroidogenic promoters independent of changes in Sf1 expression level. To investigate Sf1-independent effects of βcat on steroidogenesis, we used Affymetrix gene expression profiling of Wnt-responsive cells in vivo and in vitro. One candidate gene identified, Ccdc80, encodes a secreted protein with unknown signaling mechanisms. We report that Ccdc80 is a novel βcat-regulated gene in adrenocortical cells. Treatment of adrenocortical cells with media containing secreted Ccdc80 partially phenocopies βcat-induced suppression of steroidogenesis, albeit through an Sf1-independent mechanism. This study reveals multiple mechanisms of βcat-mediated suppression of steroidogenesis and suggests that Wnt/βcat signaling may regulate adrenal homeostasis by inhibiting fasciculata differentiation and promoting the undifferentiated state of progenitor cells.

Adrenal cancer in 2013: Time to individualize treatment for adrenocortical cancer?

2013 was a good year for adrenocortical cancer, as the new knowledge gained holds great promise for patients. Advances were made in genetics, epigenetics, the advent of related technological and bioinformatic tools, and the feasibility of massive screening of people and samples.

Beta-catenin is vital for the integrity of mouse embryonic stem cells

β-Catenin mediated Wnt-signaling is assumed to play a major function in embryonic stem cells in maintaining their stem cell character and the exit from this unique trait. The complexity of β-catenin action and conflicting results on the role of β-catenin in maintaining the pluripotent state have made it difficult to understand its precise cellular and molecular functions. To attempt this issue we have generated new genetically modified mouse embryonic stem cell lines allowing for the deletion of β-catenin in a controlled manner by taking advantage of the Cre-ER-T2 system and analyzed the effects in a narrow time window shortly after ablation. By using this approach, rather then taking long term cultured β-catenin null cell lines we demonstrate that β-catenin is dispensable for the maintenance of pluripotency associated genes. In addition we observed that the removal of β-catenin leads to a strong increase of cell death, the appearance of multiple clustered functional centrosomes most likely due to a mis-regulation of the polo-like-kinase 2 and furthermore, alterations in chromosome segregation. Our study demonstrates the importance of β-catenin in maintaining correct cellular functions and helps to understand its role in embryonic stem cells.

The roles of Notch3 on the cell proliferation and apoptosis induced by CHIR99021 in NSCLC cell lines: a functional link between Wnt and Notch signaling pathways

Wnt and Notch signaling pathways both play essential roles and interact closely in development and carcinogenesis, but their interaction in non-small-cell lung cancer (NSCLC) is poorly unknown. Here we investigated the effects of CHIR99021, a Wnt signaling agonist, or Notch3-shRNA, or the combined application of CHIR99021 and Notch3-shRNA on cell proliferation and apoptosis, as well as the expressions of Notch3, its downstream genes, cyclinA and caspase-3. Our results showed that CHIR99021 up-regulated the expression of Notch3 protein and HES1 and HEYL mRNA. CHIR99021 promoted cell proliferation and the expression of cyclinA, which were inhibited by Notch3-shRNA in these three cell lines. Moreover, Notch3-shRNA significantly attenuated the positive effects of CHIR99021 on cell proliferation and cyclinA in H460 and H157. As for apoptosis, Notch3-shRNA induced cell apoptosis and increased the expression of caspase-3, whereas CHIR99021 showed the different effects in these three cell lines. The inhibitory effect of CHIR99021 on apoptosis was significantly weakened by Notch3-shRNA only in H460. Overall, although the effects of CHIR99021 and the combined application of CHIR99021 and Notch3-shRNA on the cell proliferation and apoptosis aren’t completely similar in the three cell lines, our findings still indicate that Notch3 signaling can be activated by canonical Wnt signaling and a functional link between Wnt and Notch signaling pathways exists in NSCLC, at least, which partially is associated with their regulations on the expressions of cyclinA and caspase-3.

MicroRNA-205 suppresses the oral carcinoma oncogenic activity via down-regulation of Axin-2 in KB human oral cancer cell

MicroRNA (miRNA) is a small noncoding RNA molecule, 19-25 nucleotides in length, which regulates several pathways including cell development, cell proliferation, carcinogenesis, apoptosis, etc. In this study, the over-expression of microRNA-205 (miR-205) increased the number of apoptotic cells by at least 4 times compared to the control. In addition, over-expressed miRNA in KB oral cancer cells triggered apoptosis via the caspase cascade, including the cleavage of caspase-9, caspase-7, caspase-3, and PARP. Flow cytometry showed that apoptotic cell death was increased significantly by 35.33% in KB oral cancer cells with over-expressed miR-205 compared to the control. The microarray data showed that axis inhibitor protein 2 (Axin2) was down-regulated in KB oral cancer cells transfected with miR-205. In addition, Axin2 was down-regulated by approximately 50% by over-expressed miR-205 at both the mRNA and protein levels. Interestingly, Axin2 was up-regulated in KB oral cancer compared to human normal oral keratinocytes. Furthermore, the cell cytotoxicity and apoptotic population of KB oral cancer cells were increased significantly after Axin2 siRNA transfection. These results suggest that Axin2 is might be as potential oncogene in KB oral cancer cells. The luciferase assay showed that over-expressed miR-205 in KB oral cancer cells suppressed AXIN2 expression through an interaction with its own binding site at AXIN2 3'UTR (64-92). These results suggest that miR-205 is a novel anti-oncogenic miRNA in KB oral cancer cells, and may have potential applications in oral cancer therapy.