Changes in microRNA expression in the MG-63 osteosarcoma cell line compared with osteoblasts

Osteosarcoma (OS) is the most common primary malignant bone tumor, particularly in adolescents and young adults. Early diagnosis remains a significant problem in the clinical treatment of OS as we remain far from a comprehensive understanding of the molecular genetic mechanisms and the biology involved. In addition, microRNAs (miRNAs or miRs), a large family of small non-coding RNAs, may provide a greater understanding of OS as they play a complex role in gene expression regulation in vitro and in vivo. In the current study, the differential expression profiles of miRNAs between OS and osteoblast cell lines were investigated by miRNA microarrays and real-time quantitative PCR (RT-qPCR). A total of 268 miRNAs were identified that were significantly dysregulated in OS compared with the osteoblast cell line, including miR-9, miR-99, miR-195, miR-148a and miR-181a, which had been validated as overexpressed, and miR-143, miR-145, miR-335 and miR-539, which were confirmed to be downregulated. This differential expression may aid future OS diagnosis and prognosis prediction and illustration of the potential mechanisms in the oncogenesis, development and metastasis of OS. Bioinformatic research on these differentially expressed miRNAs suggests that they are able to regulate the biological behaviors of OS in a complex and effective manner. Further study on the function of these miRNAs is likely to provide new insights into OS biology and treatment.

Current and emerging therapeutic options in adrenocortical cancer treatment

Adrenocortical carcinoma (ACC) is a very rare endocrine tumour, with variable prognosis, depending on tumour stage and time of diagnosis. The overall survival is five years from detection. Radical surgery is considered the therapy of choice in the first stages of ACC. However postoperative disease-free survival at 5 years is only around 30% and recurrence rates are frequent. o,p'DDD (ortho-, para'-, dichloro-, diphenyl-, dichloroethane, or mitotane), an adrenolytic drug with significant toxicity and unpredictable therapeutic response, is used in the treatment of ACC. Unfortunately, treatment for this aggressive cancer is still ineffective. Over the past years, the growing interest in ACC has contributed to the development of therapeutic strategies in order to contrast the neoplastic spread. In this paper we discuss the most promising therapies which can be used in this endocrine neoplasia.

The insulin and igf-I pathway in endocrine glands carcinogenesis

Endocrine cancers are a heterogeneous group of diseases that may arise from endocrine cells in any gland of the endocrine system. These malignancies may show an aggressive behavior and resistance to the common anticancer therapies. The etiopathogenesis of these tumors remains mostly unknown. The normal embryological development and differentiation of several endocrine glands are regulated by specific pituitary tropins, which, in adult life, control the function and trophism of the endocrine gland. Pituitary tropins act in concert with peptide growth factors, including the insulin-like growth factors (IGFs), which are considered key regulators of cell growth, proliferation, and apoptosis. While pituitary TSH is regarded as tumor-promoting factor for metastatic thyroid cancer, the role of other pituitary hormones in endocrine cancers is uncertain. However, multiple molecular abnormalities of the IGF system frequently occur in endocrine cancers and may have a role in tumorigenesis as well as in tumor progression and resistance to therapies. Herein, we will review studies indicating a role of IGF system dysregulation in endocrine cancers and will discuss the possible implications of these findings for tumor prevention and treatment, with a major focus on cancers from the thyroid, adrenal, and ovary, which are the most extensively studied.

Single nucleotide polymorphism microarray analysis in cortisol-secreting adrenocortical adenomas identifies new candidate genes and pathways

The genetic mechanisms underlying adrenocortical tumor development are still largely unknown. We used high-resolution single nucleotide polymorphism microarrays (Affymetrix SNP 6.0) to detect copy number alterations (CNAs) and copy-neutral losses of heterozygosity (cnLOH) in 15 cortisol-secreting adrenocortical adenomas with matched blood samples. We focused on microalterations aiming to discover new candidate genes involved in early tumorigenesis and/or autonomous cortisol secretion. We identified 962 CNAs with a median of 18 CNAs per sample. Half of them involved noncoding regions, 89% were less than 100 kb, and 28% were found in at least two samples. The most frequently gained regions were 5p15.33, 6q16.1, 7p22.3-22.2, 8q24.3, 9q34.2-34.3, 11p15.5, 11q11, 12q12, 16q24.3, 20p11.1-20q21.11, and Xq28 (≥20% of cases), most of them being identified in the same three adenomas. These regions contained among others genes like NOTCH1, CYP11B2, HRAS, and IGF2. Recurrent losses were less common and smaller than gains, being mostly localized at 1p, 6q, and 11q. Pathway analysis revealed that Notch signaling was the most frequently altered. We identified 46 recurrent CNAs that each affected a single gene (31 gains and 15 losses), including genes involved in steroidogenesis (CYP11B1) or tumorigenesis (CTNNB1, EPHA7, SGK1, STIL, FHIT). Finally, 20 small cnLOH in four cases affecting 15 known genes were found. Our findings provide the first high-resolution genome-wide view of chromosomal changes in cortisol-secreting adenomas and identify novel candidate genes, such as HRAS, EPHA7, and SGK1. Furthermore, they implicate that the Notch1 signaling pathway might be involved in the molecular pathogenesis of adrenocortical tumors.

Combination of sorafenib and everolimus impacts therapeutically on adrenocortical tumor models

Treatment options are insufficient in patients with adrenocortical carcinoma (ACC). Based on the efficacy of sorafenib, a tyrosine kinase inhibitor, and everolimus, an inhibitor of the mammalian target of rapamycin in tumors of different histotype, we aimed at testing these drugs in adrenocortical cancer models. The expression of vascular endothelial growth factor and its receptors (VEGFR1-2) was studied in 18 ACCs, 33 aldosterone-producing adenomas, 12 cortisol-producing adenomas, and six normal adrenal cortex by real-time PCR and immunohistochemistry and by immunoblotting in SW13 and H295R cancer cell lines. The effects of sorafenib and everolimus, alone or in combination, were tested on primary adrenocortical cultures and SW13 and H295R cells by evaluating cell viability and apoptosis in vitro and tumor growth inhibition of tumor cell line xenografts in immunodeficient mice in vivo. VEGF and VEGFR1-2 were detected in all samples and appeared over-expressed in two-thirds of ACC specimens. Dose-dependent inhibition of cell viability was observed particularly in SW13 cells after 24 h treatment with either drug; drug combination produced markedly synergistic growth inhibition. Increasing apoptosis was observed in tumor cells treated with the drugs, particularly with sorafenib. Finally, a significant mass reduction and increased survival were observed in SW13 xenograft model undergoing treatment with the drugs in combination. Our data suggest that an autocrine VEGF loop may exist within ACC. Furthermore, a combination of molecularly targeted agents may have both antiangiogenic and direct antitumor effects and thus could represent a new therapeutic tool for the treatment of ACC.

Altered miRNA and gene expression in acute myeloid leukemia with complex karyotype identify networks of prognostic relevance

Recently, the p53-miR-34a network has been identified to have an important role in tumorigenesis. As in acute myeloid leukemia with complex karyotype (CK-AML) TP53 alterations are the most common known molecular lesion, we further analyzed the p53-miR-34a axis in a large cohort of CK-AML with known TP53 status (TP53(altered), n=57; TP53(unaltered), n=31; altered indicates loss and/or mutation of TP53). Profiling microRNA (miRNA) expression delineated TP53 alteration-associated miRNA profiles, and identified miR-34a and miR-100 as the most significantly down- and upregulated miRNA, respectively. Moreover, we found a distinct miR-34a expression-linked gene expression profile enriched for genes belonging to p53-associated pathways, and implicated in cell cycle progression or apoptosis. Clinically, low miR-34a expression and TP53 alterations predicted for chemotherapy resistance and inferior outcome. Notably, in TP53(unaltered) CK-AML, high miR-34a expression predicted for inferior overall survival (OS), whereas in TP53(biallelic altered) CK-AML, high miR-34a expression pointed to better OS. Thus, detailed molecular profiling links impaired p53 to decreased miR-34a expression, but also identifies p53-independent miR-34a induction mechanisms as shown in TP53(biallelic altered) cell lines treated with 15-deoxy-Δ(12,14)-prostaglandin. An improved understanding of this mechanism might provide novel therapeutic options to restore miR-34a function and thereby induce cell cycle arrest and apoptosis in TP53(altered) CK-AML.

The next generation of therapies for adrenocortical cancers

Adrenocortical carcinoma (ACC) is a rare cancer for which few treatment options have been available. Currently, the best available treatment involves combination chemotherapy with the adrenolytic drug mitotane, although the response rate remains modest. Over the past 10 years there has been renewed interest in the field owing to the recognition that targeted therapies may provide new avenues for effective treatment of this deadly disease. Molecular analyses have revealed specific signaling alterations in ACC, and advances in drug development have generated the tools to block these pathways. Although convincing evidence for the effectiveness of targeted therapies is not currently available, these studies are in progress and should shift the prognosis of this disease in the years to come.

Ligand-independent actions of the orphan receptors/corepressors DAX-1 and SHP in metabolism, reproduction and disease

DAX-1 and SHP are two closely related atypical orphan members of the nuclear receptor (NR) family that make up the NR0B subfamily. They combine properties of typical NRs and of NR-associated coregulators: both carry the characteristic NR ligand-binding domain but instead of a NR DNA-binding domain they have unique N-terminal regions that contain LxxLL-related NR-binding motifs often found in coregulators. Recent structural data indicate that DAX-1 lacks a ligand-binding pocket and thus should rely on ligand-independent mechanisms of regulation. This might be true, but remains to be proven, for SHP as well. DAX-1 and SHP have in common that they act as transcriptional corepressors of cholesterol metabolism pathways that are related on a molecular level. However, the expression patterns of the two NRs are largely different, with some notable exceptions, and so are the physiological processes they regulate. DAX-1 is mainly involved in steroidogenesis and reproductive development, while SHP plays major roles in maintaining cholesterol and glucose homeostasis. This review highlights the key similarities and differences between DAX-1 and SHP with regard to structure, function and biology and considers what can be learnt from recent research advances in the field. This article is part of a Special Issue entitled 'Orphan Receptors'.

SNP array profiling of childhood adrenocortical tumors reveals distinct pathways of tumorigenesis and highlights candidate driver genes

CONTEXT

Childhood adrenocortical tumors (ACT) are rare malignancies, except in southern Brazil, where a higher incidence rate is associated to a high frequency of the founder R337H TP53 mutation. To date, copy number alterations in these tumors have only been analyzed by low-resolution comparative genomic hybridization.

OBJECTIVE

We analyzed an international series of 25 childhood ACT using high-resolution single nucleotide polymorphism arrays to: 1) detect focal copy number alterations highlighting candidate driver genes; and 2) compare genetic alterations between Brazilian patients carrying the R337H TP53 mutation and non-Brazilian patients.

RESULTS

We identified 16 significantly recurrent chromosomal alterations (q-value < 0.05), the most frequent being -4q34, +9q33-q34, +19p, loss of heterozygosity (LOH) of chromosome 17 and 11p15. Focal amplifications and homozygous deletions comprising well-known oncogenes (MYC, MDM2, PDGFRA, KIT, MCL1, BCL2L1) and tumor suppressors (TP53, RB1, RPH3AL) were identified. In addition, eight focal deletions were detected at 4q34, defining a sharp peak region around the noncoding RNA LINC00290 gene. Although non-Brazilian tumors with a mutated TP53 were similar to Brazilian tumors, those with a wild-type TP53 displayed distinct genomic profiles, with significantly fewer rearrangements (P = 0.019). In particular, three alterations (LOH of chromosome 17, +9q33-q34, and -4q34) were significantly more frequent in TP53-mutated samples. Finally, two of four TP53 wild-type tumors displayed as sole rearrangement a copy-neutral LOH of the imprinted region at 11p15, supporting a major role for this region in ACT development.

CONCLUSIONS

Our findings highlight potential driver genes and cellular pathways implicated in childhood ACT and demonstrate the existence of different oncogenic routes in this pathology.

The molecular basis of adrenocortical cancer

Adrenocortical tumors (ACTs) are common, and most are benign adrenocortical adenomas (ACAs). Malignant adrenocortical carcinoma (ACC) is a rare tumor type and is observed at the rate of one or two cases per million annually. ACTs are classified as either ACAs or ACCs by histopathologic methods that are based on nine Weiss scoring criteria, including the nuclear grade, mitotic rate, presence of necrosis, and others. In this review, we describe the findings of studies that have examined the molecular basis of ACTs, and we compare transcriptome analysis with other diagnostic approaches. ACTs are occasionally difficult to classify. Therefore, molecular techniques, such as microarray analysis, have recently been applied to overcome some of these diagnostic problems. We also discuss the likelihood of the diagnosis and discernment between ACAs and ACCs based on the molecular tests. To show the recent progress in understanding the etiology of ACTs, we highlight the relationship between genetic analysis and transcriptome analysis. We attempt to understand the role of abnormal cell growth and steroid hormone secretion. Genetic and transcriptome analyses have improved our understanding of ACTs considerably, yet many unanswered questions remain.

The role of mTOR inhibitors in the inhibition of growth and cortisol secretion in human adrenocortical carcinoma cells

Patients with adrenocortical carcinoma (ACC) need new treatment options. The aim of this study was to evaluate the effects of the mTOR inhibitors sirolimus and temsirolimus on human ACC cell growth and cortisol production. In H295, HAC15, and SW13 cells, we have evaluated mTOR, IGF2, and IGF1 receptor expressions; the effects of sirolimus and temsirolimus on cell growth; and the effects of sirolimus on apoptosis, cell cycle, and cortisol production. Moreover, the effects of sirolimus on basal and IGF2-stimulated H295 cell colony growth and on basal and IGF1-stimulated phospho-AKT, phospho-S6K1, and phospho-ERK in H295 and SW13 were studied. Finally, we have evaluated the effects of combination treatment of sirolimus with an IGF2-neutralizing antibody. We have found that H295 and HAC15 expressed IGF2 at a >1800-fold higher level than SW13. mTOR inhibitors suppressed cell growth in a dose-/time-dependent manner in all cell lines. SW13 were the most sensitive to these effects. Sirolimus inhibited H295 colony surviving fraction and size. These effects were not antagonized by IGF2, suggesting the involvement of other autocrine regulators of mTOR pathways. In H295, sirolimus activated escape pathways. The blocking of endogenously produced IGF2 increased the antiproliferative effects of sirolimus on H295. Cortisol production by H295 and HAC15 was inhibited by sirolimus. The current study demonstrates that mTOR inhibitors inhibit the proliferation and cortisol production in ACC cells. Different ACC cells have different sensitivity to the mTOR inhibitors. mTOR could be a target for the treatment of human ACCs, but variable responses might be expected. In selected cases of ACC, the combined targeting of mTOR and IGF2 could have greater effects than mTOR inhibitors alone.

The Weiss score and beyond--histopathology for adrenocortical carcinoma

The pathological diagnosis of adrenocortical carcinoma (ACC) is still challenging for its rarity and the presence of special variants (pediatric, oncocytic, myxoid, and sarcomatoid). It is based on the recognition at light microscopy of at least three among nine morphological parameters, according to the Weiss scoring system, which has been introduced 27 years ago and nowadays is the most widely employed. Nevertheless, the diagnostic performance of this system is very high but does not reach a sensitivity and specificity of 100%, its diagnostic applicability is potentially low among non-expert pathologists, and a group of borderline cases with only one or two criteria exist of uncertain behavior. Moreover, it is scarcely reproducible in the ACC morphological variants. In fact, specifically for the pure oncocytic neoplasms that seem to have a better prognosis in comparison to the conventional ACCs, a modified system (the Lin-Weiss-Bisceglia) has been proposed. With the aim to simplify the ACC diagnosis, 2 years ago, the "reticulin" diagnostic algorithm has been proposed, based on the observation that the tumoral reticulin framework (highlighted by reticulin silver-based histochemical staining) is consistently disrupted in malignant cases but only in a small subset of benign cases. Following this algorithm, in the presence of reticulin alterations, malignancy is further defined through the identification of at least one of the following parameters: necrosis, high mitotic rate, and venous invasion. As a complement to the morphological approach, some immunohistochemical markers (such as steroidogenic factor 1) have been proposed as diagnostic and prognostic adjuncts but still lack wide clinical validation.

Molecular markers of adrenocortical tumors

Adrenocortical tumors are common and incidentally discovered in up to 14% of axial imaging studies performed for other indications. Most of these tumors are nonfunctioning but may require removal because of the risk of adrenocortical carcinoma. Unfortunately, most clinical and imaging features are still not accurate enough to allow definitive diagnosis and an increasing number of patients undergo adrenalectomy to exclude a cancer diagnosis. Adrenocortical carcinoma is an aggressive malignancy with no effective therapy for patients with locally advanced and metastatic disease. Studies using new genomic approaches including mRNA, miRNA, methylation, and CGH profiling have identified dysregulated genes and pathways that may have clinical implications in improved molecular diagnosis and prognostication of adrenocortical cancer (ACC). In this review, we highlight recent advances in the molecular diagnosis of adrenocortical tumors.

Insulin-like growth factor system on adrenocortical tumorigenesis

The insulin-like growth factor (IGF) signaling pathway has many important roles in normal cell growth and development. Remarkably, all of the components of this system (IGFs, receptors, and binding proteins) are expressed in human fetal adrenals. Beckwith-Wiedemann syndrome, a congenital overgrowth disorder characterized by a high risk of development of childhood tumors, is also distinguished by a high incidence of adrenocortical carcinomas. This disease has been associated with structural abnormalities at the 11p15 locus, which harbors the IGF2 gene as well as the genes coding for insulin, H19, and p57kip2. Notably, rearrangements at the 11p15 locus and overexpression of IGF2 were also described in sporadic adrenocortical tumors. In addition, the IGF2 overexpression was exclusively demonstrated in adults with adrenocortical tumors as a frequent feature of the malignant state. More recent studies demonstrated that the interaction of IGF-2 with IGF receptor type 1 (IGF-1R) plays also a pivotal role in adrenocortical tumorigenesis. IGF1R expression levels were significantly higher in pediatric adrenocortical carcinomas, suggesting that IGF1R expression represents a potential prognostic marker in this group of patients. These findings indicate that the IGF system is an important pathway for autonomous growth of adrenocortical cells and potential inhibitors of this system could be a rational therapeutic target for adrenocortical tumors.

Differences in the molecular mechanisms of adrenocortical tumorigenesis between children and adults

Adrenocortical carcinoma (ACC) is a rare malignancy with poor prognosis. The incidence of pediatric adrenocortical tumors (ACT) is remarkably high in Southern Brazil, where it is estimated to be 15 times greater than the world occurrence, due to a high frequency of a germline mutation (p.R337H) of the TP53 gene. Differently from adults, pediatric adrenocortical neoplasms with apparently poor prognosis based on histopathological features have often a good clinical outcome. A high Weiss score is definitely not a good predictor of survival in children, but it is much more discriminative of a poor outcome in adult tumors. Besides important differences in prognosis, adrenocortical tumorigenesis has distinct patterns between children and adults. In this review, we summarize recent data from ours and other Institutions, showing that the prognostic importance of molecular markers is striking different between pediatric and adult ACT. Although the majority of pediatric ACT are associated with p.R337H germline mutation, it is not a predictor of poor outcome in children and adolescents with ACT. On the other side, TP53 somatic mutations define a subgroup of adult ACC with different tumorigenesis and unfavorable prognosis. IGF system has a central role in the malignant phenotype of ACT, but in adult tumors it is mediated by IGF2 over-expression and in pediatric tumors by IGF1R over-expression. Finally, SF1 over-expression is associated with decreased overall survival and recurrence-free survival in adult ACC, but not in the pediatric group. In conclusion, discriminating benign and malignant behavior is more challenging in pediatric ACT than in adult tumors.

Xenograft models for preclinical drug testing: implications for adrenocortical cancer

Adrenocortical carcinoma (ACC) is a very rare but aggressive tumor, whose biological and cellular features and processes underlying the development, progression and metastatic evolution are still obscure. Despite many attempts to use general cytostatic and cytotoxic drugs, the only available drug therapy for advanced ACC is still represented by mitotane (MTT). However, the mechanism of action of this adrenolytic derivative of the pesticide DDT has still been poorly characterized. In this context, the development of more specific drugs for ACC treatment is based on the knowledge of the molecular pathways involved in the tumor growth. Xenograft models for the screening of such drugs at preclinical levels is mandatory. In the first part of this review, we will summarize the "pro" and "con" of the different xenograft models available for anticancer drug testing in different types of tumors in general and in the last part, we will focus on the preclinical evidence obtained so far with the use of such models applied to drug screening for anticancer effects in ACC.

Molecular epidemiology of adrenocortical tumors in southern Brazil

The high frequency of TP53 R337H carriers in southern Brazil is responsible for the highest known incidence of childhood adrenocortical tumor (ACT). Our aims were to examine other contributing mutations, age-related risk factors, epidemiological differences in ACT and to shed light on a method for increasing the survival rate of children. The fetal zone of the adrenal cortex is believed to be one of the tissues most susceptible to adenoma or carcinoma formation due to loss of p53 function. The founder germline R337H mutation is found in 95% of ACTs of young children, a much greater proportion than in adults. Despite intense educational campaigns about the high incidence of ACT in Paraná State, advanced cases remain common. Four advanced ACT cases (4/5) were admitted to a single institution in the first 6months of 2011 in Paraná State, none of the families knew about ACT, and 2 reported no familial cancer syndrome. Curative resection is possible when a small ACT is detected early.

Dysregulation of microRNAs in adrenocortical tumors

MicroRNAs (miRNAs) are short non-coding RNAs that are involved in the epigenetic regulation of cellular processes. Different malignancies are often associated with the deregulation of specific sets of miRNAs. The prognosis of adrenocortical cancers (ACCs) is very poor as compared to adrenocortical adenomas (ACAs), and even within ACCs there are cases with better disease specific survival. An improved understanding of the pathobiology of this disease will therefore be useful in facilitating better management of ACCs as well as distinguishing high risk versus low risk subgroups. One third of coding genes are regulated by miRNAs and therefore changes in miRNA expression may be associated with cancer development and progression. In this review we summarize the current understanding of miRNAs in adrenocortical tumors, and highlight their potential in differentiating between ACCs and ACAs, risk stratification and prognosis.

SF-1 expression during adrenal development and tumourigenesis

SF-1 is a master regulator of steroidogenesis whose expression is critical for normal adrenal and gonadal organogenesis. Strict maintenance of SF-1 levels is essential, and mutations causing under- or overexpression result in congenital adrenal and gonadal defects or hyperplasia, respectively. Data from transgenic mouse models points to a network of transcription factors responsible for stringent regulation of Sf-1 expression during development, which bind to intronic enhancer elements in addition to the basal promoter to specifically modulate transcription in each Sf-1-expressing tissue. Furthermore, analysis of the role of SF-1 in adrenal tumourigenesis implies that improper developmental regulation of Sf-1 expression may have postnatal consequences separate from the well-documented developmental defects.

Adrenocortical stem and progenitor cells: implications for adrenocortical carcinoma

The continuous centripetal repopulation of the adrenal cortex is consistent with a population of cells endowed with the stem/progenitor cell properties of self-renewal and pluripotency. The adrenocortical capsule and underlying undifferentiated cortical cells are emerging as critical components of the stem/progenitor cell niche. Recent genetic analysis has identified various signaling pathways including Sonic Hedgehog (Shh) and Wnt as crucial mediators of adrenocortical lineage and organ homeostasis. Shh expression is restricted to the peripheral cortical cells that express a paucity of steroidogenic genes but give rise to the underlying differentiated cells of the cortex. Wnt/β-catenin signaling maintains the undifferentiated state and adrenal fate of adrenocortical stem/progenitor cells, in part through induction of its target genes Dax1 and inhibin-α, respectively. The pathogenesis of ACC, a rare yet highly aggressive cancer with an extremely poor prognosis, is slowly emerging from studies of the stem/progenitor cells of the adrenal cortex coupled with the genetics of familial syndromes in which ACC occurs. The frequent observation of constitutive activation of Wnt signaling due to loss-of-function mutations in the tumor suppressor gene APC or gain-of-function mutation in β-catenin in both adenomas and carcinomas, suggests perhaps that the Wnt pathway serves an early or initiating insult in the oncogenic process. Loss of p53 might be predicted to cooperate with additional genetic insults such as IGF2 as both are the most common genetic abnormalities in malignant versus benign adrenocortical neoplasms. It is unclear whether other factors such as Pod1 and Pref1, which are implicated in stem/progenitor cell biology in the adrenal and/or other organs, are also implicated in the etiology of adrenocortical carcinoma. The rarity and heterogeneous presentation of ACC makes it difficult to identify the cellular origin and the molecular progression to cancer. A more complete understanding of adrenocortical stem/progenitor cell biology will invariably aid in characterization of the molecular details of ACC tumorigenesis and may offer new options for therapeutic intervention.

Sonic hedgehog signaling during adrenal development

It has been speculated for a number of years that Sonic hedgehog (Shh) signaling plays an important role in adrenal development. Over the past two years several reports have described the expression and function of Shh pathway genes in the adrenal cortex, using primarily mouse models. The key findings are that Shh signals produced by a population of partially differentiated cortical cells located in the outer cortex/zona glomerulosa are received by non-cortical mesenchymal cells located predominantly in the overlying capsule. This signal is required for growth of both the capsule and the cortex, but not for cortical zonation or steroidogenic cell differentiation. Using molecular genetic tools to define the adrenocortical cell lineages that are descended from both Shh signaling and receiving cells, both capsule and cortical cells were found to have properties of adrenocortical stem and/or progenitor cells. Here we place these observations within the context of prior studies on adrenal development, postnatal adrenal maintenance and adrenocortical stem/progenitor cell lineages.

The cAMP pathway and the control of adrenocortical development and growth

In the last 10 years, extensive studies showed that the cAMP pathway is deregulated in patients suffering from adrenocortical tumours, and particularly in primary pigmented nodular adrenocortical disease (PPNAD). Here we describe how evidence arising from the analysis of patients' data, mouse models and in vitro experiments, have shed light on the cAMP pathway as a central player in adrenal physiopathology. We also show how novel data generated from mouse models may point to new targets for potential therapies.

Down-regulation of the microRNA-99 family members in head and neck squamous cell carcinoma

OBJECTIVES

MicroRNA deregulation is a critical event in head and neck squamous cell carcinoma (HNSCC). Several microRNA profiling studies aimed at deciphering the microRNA signatures of HNSCC have been reported, but there tends to be poor agreement among studies. The objective of this study was to survey the published microRNA profiling studies on HNSCC, and to assess the commonly deregulated microRNAs in an independent sample set.

MATERIALS AND METHODS

Meta-analysis of 13 published microRNA profiling studies was performed to define microRNA signatures in HNSCC. Selected microRNAs (including members of miR-99 family) were evaluated in an independent set of HNSCC cases. The potential contributions of miR-99 family to the tumorigenesis of HNSCC were assessed by in vitro assays.

RESULTS

We identified 67 commonly deregulated microRNAs. The up-regulation of miR-21, miR-155, miR-130b, miR-223 and miR-31, and the down-regulation of miR-100, miR-99a and miR-375 were further validated in an independent set of HNSCC cases with quantitative RT-PCR. Among these validated microRNAs, miR-100 and miR-99a belong to the miR-99 family. Our in vitro study demonstrated that restoration of miR-100 to the HNSCC cell lines suppressed cell proliferation and migration, and enhanced apoptosis. Furthermore, ectopic transfection of miR-99 family members down-regulated the expression of insulin-like growth factor 1 receptor (IGF1R) and mechanistic target of rapamycin (mTOR) genes.

CONCLUSION

In summary, we described a panel of frequently deregulated microRNAs in HNSCC, including members of miR-99 family. The deregulation of miR-99 family contributes to the tumorigenesis of HNSCC, in part by targeting IGF1R and mTOR signaling pathways.

Upregulated JAG1 enhances cell proliferation in adrenocortical carcinoma

PURPOSE

The purpose of this study was to examine the expression and molecular significance of JAG1, a ligand for the Notch developmental signaling pathway, in adrenocortical carcinoma (ACC).

EXPERIMENTAL DESIGN

Human microarray data were analyzed for genes expressing ligands for the Notch pathway and validated with quantitative real-time PCR (QPCR) and immunoblots of RNA and protein, respectively. ACC cells lines were assessed for Notch pathway member expression by immunoblot, QPCR, and immunofluorescence. Notch pathway activity was also determined using a reporter gene (luciferase) activation. Proliferation experiments using a Jag1 knockdown strategy (Jag1KD) and an inhibitor of Notch-dependent transcription (DNMaml) used a coculture system with fluorescence-activated cell-sorting (FACS) analysis. Tumor stage and mitotic rate of human ACC samples were correlated to JAG1 expression.

RESULTS

The Notch ligand JAG1 mRNA and protein are upregulated in ACCs. JAG1 upregulation can be modeled in the Y1 mouse ACC cell line that expresses Jag1, Notch receptors, downstream signaling molecules, and exhibits density-dependent Notch activation. Jag1 enhances cell proliferation through activation of canonical Notch signaling as shown through Jag1KD and coculture experiments. Inhibition of Notch signaling at the level of postreceptor signaling (DNMaml), results in similar inhibition of cell proliferation. Analysis of clinical data indicates that Jag1 expression correlates with both grade and stage of ACCs, supporting a role of JAG1-dependent Notch activation in late-stage ACCs.

CONCLUSIONS

JAG1 is the primary upregulated Notch ligand in ACCs and enhances ACC cell proliferation and tumor aggressiveness in a non-cell-autonomous manner through activation of Notch signaling in adjacent cells.

Knockdown of SF-1 and RNF31 affects components of steroidogenesis, TGFβ, and Wnt/β-catenin signaling in adrenocortical carcinoma cells

The orphan nuclear receptor Steroidogenic Factor-1 (SF-1, NR5A1) is a critical regulator of development and homeostasis of the adrenal cortex and gonads. We recently showed that a complex containing E3 ubiquitin ligase RNF31 and the known SF-1 corepressor DAX-1 (NR0B1) interacts with SF-1 on target promoters and represses transcription of steroidogenic acute regulatory protein (StAR) and aromatase (CYP19) genes. To further evaluate the role of SF-1 in the adrenal cortex and the involvement of RNF31 in SF-1-dependent pathways, we performed genome-wide gene-expression analysis of adrenocortical NCI-H295R cells where SF-1 or RNF31 had been knocked down using RNA interference. We find RNF31 to be deeply connected to cholesterol metabolism and steroid hormone synthesis, strengthening its role as an SF-1 coregulator. We also find intriguing evidence of negative crosstalk between SF-1 and both transforming growth factor (TGF) β and Wnt/β-catenin signaling. This crosstalk could be of importance for adrenogonadal development, maintenance of adrenocortical progenitor cells and the development of adrenocortical carcinoma. Finally, the SF-1 gene profile can be used to distinguish malignant from benign adrenocortical tumors, a finding that implicates SF-1 in the development of malignant adrenocortical carcinoma.

Role of SF-1 and DAX-1 during differentiation of P19 cells by retinoic acid

Retinoic acid (RA) is critical for embryonic development and cellular differentiation. Previous work in our laboratory has shown that blocking the RA-dependent increase in pre-β cell leukemia transcription factors (PBX) mRNA and protein levels in P19 cells prevents endodermal and neuronal differentiation. Dosage-sensitive sex reversal, adrenal hypoplasia critical region, on chromosome X, gene 1 (DAX-1) and steroidogenic factor (SF-1) were found by microarray analysis to be regulated by PBX in P19 cells. To determine the roles of DAX-1 and SF-1 during RA-dependent differentiation, P19 cells that inducibly express either FLAG-DAX-1 or FLAG-SF-1 were prepared. Unexpectedly, overexpression of DAX-1 had no effect on the RA-induced differentiation of P19 cells to either endodermal or neuronal cells. However, SF-1 overexpression prevented the RA-dependent loss of OCT-4, DAX-1 and the increase in COUP-TFI, COUP-TFII, and ETS-1 mRNA levels during the commitment stages of both endodermal and neuronal differentiation. Surprisingly, continued expression of SF-1 for 7 days caused the RA-independent loss of OCT-4 protein and RA-dependent loss of SSEA-1 expression. Despite the loss of well-characterized pluripotency markers, these cells did not terminally differentiate into either endodermal or neuronal cells. Instead, the cells gained the expression of many steroidogenic enzymes with a pattern consistent with adrenal cells. Finally, we found evidence for a feedback loop in which PBX reduces SF-1 mRNA levels while continued SF-1 expression blocks the RA-dependent increase in PBX levels. Taken together, these data demonstrate that SF-1 plays a dynamic role during the differentiation of P19 cells and potentially during early embryogenesis.

How do they do Wnt they do?: regulation of transcription by the Wnt/β-catenin pathway

Wnt/β-catenin signalling is known to play many roles in metazoan development and tissue homeostasis. Misregulation of the pathway has also been linked to many human diseases. In this review, specific aspects of the pathway's involvement in these processes are discussed, with an emphasis on how Wnt/β-catenin signalling regulates gene expression in a cell and temporally specific manner. The T-cell factor (TCF) family of transcription factors, which mediate a large portion of Wnt/β-catenin signalling, will be discussed in detail. Invertebrates contain a single TCF gene that contains two DNA-binding domains, the high mobility group (HMG) domain and the C-clamp, which increases the specificity of DNA binding. In vertebrates, the situation is more complex, with four TCF genes producing many isoforms that contain the HMG domain, but only some of which possess a C-clamp. Vertebrate TCFs have been reported to act in concert with many other transcription factors, which may explain how they obtain sufficient specificity for specific DNA sequences, as well as how they achieve a wide diversity of transcriptional outputs in different cells.

Combined expression of BUB1B, DLGAP5, and PINK1 as predictors of poor outcome in adrenocortical tumors: validation in a Brazilian cohort of adult and pediatric patients

BACKGROUND

A recent microarray study identified a set of genes whose combined expression patterns were predictive of poor outcome in a cohort of adult adrenocortical tumors (ACTs). The difference between the expression values measured by qRT-PCR of DLGAP5 and PINK1 genes was the best molecular predictor of recurrence and malignancy. Among the adrenocortical carcinomas, the combined expression of BUB1B and PINK1 genes was the most reliable predictor of overall survival. The prognostic and molecular heterogeneity of ACTs raises the need to study the applicability of these molecular markers in other cohorts.

OBJECTIVE

To validate the combined expression of BUB1B, DLGAP5, and PINK1 as outcome predictor in ACTs from a Brazilian cohort of adult and pediatric patients.

PATIENTS AND METHODS

BUB1B, DLGAP5, and PINK1 expression was assessed by quantitative PCR in 53 ACTs from 52 patients - 24 pediatric and 28 adults (one pediatric patient presented a bilateral asynchronous ACT).

RESULTS

DLGAP5-PINK1 and BUB1B-PINK1 were strong predictors of disease-free survival and overall survival, respectively, among adult patients with ACT. In the pediatric cohort, these molecular predictors were only marginally associated with disease-free survival but not with overall survival.

CONCLUSION

This study confirms the prognostic value of the combined expression of BUB1B, DLGAP5, and PINK1 genes in a Brazilian group of adult ACTs. Among pediatric ACTs, other molecular predictors of outcome are required.

A New Presentation of the Chimeric CYP11B1/CYP11B2 Gene With Low Prevalence of Primary Aldosteronism and Atypical Gene Segregation Pattern

Familial hyperaldosteronism type I is caused by an unequal crossover of 11β-hydroxylase (CYP11B1) and aldosterone synthase (CYP11B2) genes, giving rise to a chimeric CYP11B1/CYP11B2 gene (CG). We describe a family carrying a CG with high levels of free 18-hydroxycortisol but low prevalence of primary aldosteronism (PA) and an atypical CG inheritance pattern in a family of 4 generations with 16 adults and 13 children, we measured the arterial blood pressure, serum aldosterone, and plasma renin activity and then calculated the serum aldosterone:plasma renin activity ratio and urinary free 18-hydroxycortisol. We identified the CG by long-extension PCR and predicted its inheritance pattern. The CG was found in 24 of 29 subjects (10 children and 14 adults). In CG+ patients, hypertension and high 18-hydroxycortisol were prevalent (83% and 100%, respectively). High serum aldosterone:plasma renin activity ratio was more frequent in pediatric than adult patients (80% versus 36%; P <0.001). An inverse association between serum aldosterone:plasma renin activity ratio and age was observed ( r =−0.48; P =0.018). Sequence analysis identified the CYP11B1/CYP11B2 crossover in a 50-bp region spanning intron 3 of CYP11B1 and exon 4 of CYP11B2. The CG segregation differs from an autosomal disease, showing 100% of CG penetrance in generations II and III. Statistical analysis suggests that inheritance pattern was not attributed to random segregation ( P <0.001). In conclusion, we describe a family with an atypical CYP11B1/CYP11B2 gene inheritance pattern and variable phenotypic expression, where the majority of pediatric patients have primary aldosteronism. Most adults have normal aldosterone and renin levels, which could mask them as essential hypertensives.

Early development of cephalochordates (amphioxus)

The Phylum Chordata includes three groups--Vertebrata, Tunicata, and Cephalochordata. In cephalochordates, commonly called amphioxus or lancelets, which are basal in the Chordata, the eggs are small and relatively non-yolky. As in vertebrates, cleavage is indeterminate with cell fates determined gradually as development proceeds. The oocytes are attached to the ovarian follicle at the animal pole, where the oocyte nucleus is located. The cytoplasm at the opposite side of the egg, the vegetal pole, contains the future germ plasm or pole plasm, which includes determinants of the germline. After fertilization, additional asymmetries are established by movements of the egg and sperm nuclei, resulting in a concentration of mitochondria at one side of the animal hemisphere. This may be related to establishment of the dorsal/ventral axis. Patterning along the embryonic axes is mediated by secreted signaling proteins. Dorsal identity is specified by Nodal/Vg1 signaling, while during the gastrula stage, opposition between Nodal/Vg1 and BMP signaling establishes dorsal/anterior (i.e., head) and ventral/posterior (i.e., trunk/tail) identities, respectively. Wnt/β-catenin signaling specifies posterior identity while retinoic acid signaling specifies positions along the anterior/posterior axis. These signals are further modulated by a number of secreted antagonists. This fundamental patterning mechanism is conserved, with some modifications, in vertebrates.

Global microRNA expression profiling of microdissected tissues identifies miR-135b as a novel biomarker for pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is known for its poor prognosis resulting from being diagnosed at an advanced stage. Accurate early diagnosis and new therapeutic modalities are therefore urgently needed. MicroRNAs (miRNAs), considered a new class of biomarkers and therapeutic targets, may be able to fulfill those needs. Combining tissue microdissection with global miRNA array analyses, cell type-specific miRNA expression profiles were generated for normal pancreatic ductal cells, acinar cells, PDAC cells derived from xenografts and also from macrodissected chronic pancreatitis (CP) tissues. We identified 78 miRNAs differentially expressed between ND and PDAC cells providing new insights into the miRNA-driven pathophysiological mechanisms involved in PDAC development. Having filtered miRNAs which are upregulated in the three pairwise comparisons of PDAC vs. ND, PDAC vs. AZ and PDAC vs. CP, we identified 15 miRNA biomarker candidates including miR-135b. Using relative qRT-PCR to measure miR-135b normalized to miR-24 in 75 FFPE specimens (42 PDAC and 33 CP) covering a broad range of tumor content, we discriminated CP from PDAC with a sensitivity and specificity of 92.9% [95% CI=(80.5, 98.5)] and 93.4% [95% CI=(79.8, 99.3)], respectively. Furthermore, the area under the curve (AUC) value reached of 0.97 was accompanied by positive and negative predictive values of 95% and 91%, respectively. In conclusion, we report pancreatic cell-specific global miRNA profiles, which offer new candidate miRNAs to be exploited for functional studies in PDAC. Furthermore, we provide evidence that miRNAs are well-suited analytes for development of sensitive and specific aid-in-diagnosis tests for PDAC.

The role of microRNAs in neural stem cell-supported endothelial morphogenesis

Functional signaling between neural stem/progenitor cells (NSPCs) and brain endothelial cells (ECs) is essential to the coordination of organized responses during initial embryonic development and also during tissue repair, which occurs following brain injury. In this study, we investigated the molecular mechanisms underlying this functional signaling, using primary mouse brain ECs and NSPCs from embryonic mouse brain. EC/NSPC co-culture experiments have revealed that neural progenitors secrete factors supporting angiogenesis, which induce noticeable changes in endothelial morphology. We demonstrate that NSPCs influence the expression of mTOR and TGF-β signaling pathway components implicated in the regulation of angiogenesis. Endothelial morphogenesis, an essential component of vascular development, is a complex process involving gene activation and the upregulation of specific cell signaling pathways. Recently identified small molecules, called microRNAs (miRNAs), regulate the expression of genes and proteins in many tissues, including brain and vasculature. We found that NSPCs induced considerable changes in the expression of at least 24 miRNAs and 13 genes in ECs. Three NSPC-regulated EC miRNAs were identified as the potential primary mediators of this NSPC/EC interaction. We found that the specific inhibition, or overexpression, of miRNAs miR-155, miR-100, and miR-let-7i subsequently altered the expression of major components of the mTOR, TGF-β and IGF-1R signaling pathways in ECs. Overexpression of these miRNAs in ECs suppressed, while inhibition activated, the in vitro formation of capillary-like structures, a process representative of EC morphogenesis. In addition, we demonstrate that inhibition of FGF, VEGF, and TGF-β receptor signaling abolished NSPC-promoted changes in the endothelial miRNA profiles. Our findings demonstrate that NSPCs induce changes in the miRNA expression of ECs, which are capable of activating angiogenesis by modulating distinct cell signaling pathways.

mTORC1 and mTORC2 differentially regulate homeostasis of neoplastic and non-neoplastic human mast cells

Increased mast cell burden is observed in the inflamed tissues and affected organs and tissues of patients with mast cell proliferative disorders. However, normal mast cells participate in host defense, so approaches to preferentially target clonally expanding mast cells are needed. We found that mammalian target of rapamycin complex 1 (mTORC1) and 2 (mTORC2) are up-regulated in neoplastic and developing immature mast cells compared with their terminally differentiated counterparts. Elevated mTOR mRNA was also observed in bone marrow mononuclear cells of patients exhibiting mast-cell hyperplasia. Selective inhibition of mTORC1 and mTORC2 through genetic and pharmacologic manipulation revealed that, whereas mTORC1 may contribute to mast-cell survival, mTORC2 was only critical for homeostasis of neoplastic and dividing immature mast cells. The cytostatic effect of mTORC2 down-regulation in proliferating mast cells was determined to be via inhibition of cell-cycle progression. Because mTORC2 was observed to play little role in the homeostasis of differentiated, nonproliferating, mature mast cells, these data provide a rationale for adopting a targeted approaching selectively inhibiting mTORC2 to effectively reduce the proliferation of mast cells associated with inflammation and disorders of mast cell proliferation while leaving normal differentiated mast cells largely unaffected.

Macro-management of microRNAs in cell cycle progression of tumor cells and its implications in anti-cancer therapy

The cell cycle, which is precisely controlled by a number of regulators, including cyclins and cyclin-dependent kinases (CDKs), is crucial for the life cycle of mammals. Cell cycle dysregulation is implicated in many diseases, including cancer. Recently, compelling evidence has been found that microRNAs play important roles in the regulation of cell cycle progression by modulating the expression of cyclins, CDKs and other cell cycle regulators. Herein, the recent findings on the regulation of the cell cycle by microRNAs are summarized, and the potential implications of miRNAs in anti-cancer therapies are discussed.

Tumores adrenocorticais na criança: da abordagem clínica à avaliação molecular

Tumores do córtex adrenal (TCA) são mais frequentes em crianças, mas podem ocorrer em qualquer faixa etária. São classificados como funcionantes, não funcionantes (predominam no adulto), e mistos. O diagnóstico é baseado na avaliação clínica, hormonal e exames de imagem. Em crianças, o método de escolha para diferenciar entre benigno ou maligno é a classificação baseada no estadiamento do tumor. Alguns marcadores moleculares merecem destaque: além de mutações inativadoras no gene supressor tumoral TP53, há evidências de envolvimento do IGF2 em 90% de TAC malignos, e mutações no éxon 3 do gene CTNNB1 foram encontradas em 6% dos TAC pediátricos. Além disso, microRNAs podem atuar como reguladores negativos da expressão gênica e participar da tumorigênese adrenocortical. Métodos para análise da expressão gênica permitem identificar TCA com prognóstico bom ou ruim, e espera-se que esses estudos possam facilitar o desenvolvimento de drogas para tratar pacientes de acordo com as vias de sinalização específicas que estiverem alteradas.

The role of microRNA deregulation in the pathogenesis of adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is an aggressive tumor showing frequent metastatic spread and poor survival. Although recent genome-wide studies of ACC have contributed to our understanding of the disease, major challenges remain for both diagnostic and prognostic assessments. The aim of this study was to identify specific microRNAs (miRNAs) associated with malignancy and survival of ACC patients. miRNA expression profiles were determined in a series of ACC, adenoma, and normal cortices using microarray. A subset of miRNAs showed distinct expression patterns in the ACC compared with adrenal cortices and adenomas. Among others, miR-483-3p, miR-483-5p, miR-210, and miR-21 were found overexpressed, while miR-195, miR-497, and miR-1974 were underexpressed in ACC. Inhibition of miR-483-3p or miR-483-5p and overexpression of miR-195 or miR-497 reduced cell proliferation in human NCI-H295R ACC cells. In addition, downregulation of miR-483-3p, but not miR-483-5p, and increased expression of miR-195 or miR-497 led to significant induction of cell death. Protein expression of p53 upregulated modulator of apoptosis (PUMA), a potential target of miR-483-3p, was significantly decreased in ACC, and inversely correlated with miR-483-3p expression. In addition, high expression of miR-503, miR-1202, and miR-1275 were found significantly associated with shorter overall survival among patients with ACC (P values: 0.006, 0.005, and 0.042 respectively). In summary, we identified additional miRNAs associated with ACC, elucidated the functional role of four miRNAs in the pathogenesis of ACC cells, demonstrated the potential involvement of the pro-apoptotic factor PUMA (a miR-483-3p target) in adrenocortical tumors, and found novel miRNAs associated with survival in ACC.

Sunitinib Inhibits Cell Proliferation and Alters Steroidogenesis by Down-Regulation of HSD3B2 in Adrenocortical Carcinoma Cells

The multi-tyrosine kinase inhibitor sunitinib is used in the treatment of several solid tumors. Animal experiments pointed to an adrenotoxic effect of sunitinib. Therefore, we evaluated the expression of key targets of sunitinib in human adrenocortical carcinoma (ACC) tumor samples and investigated its in vitro effects in ACC cell lines. We carried out immunohistochemistry for vascular endothelial growth factor (VEGF) and its receptor (VEGF-R2) in 157 ACC samples and nine normal adrenal glands. VEGF and VEGF-R2 protein were expressed in 72 and 99% of ACC samples, respectively. Using NCI-H295 and SW13 ACC cell lines, we investigated the effects of sunitinib on cell proliferation. Sunitinib reduced dose-dependently cell viability of both NCI-H295 and SW13 cells (SW13: 0.1 μM 96 ± 7%, 1 μM 90 ± 9%*, 5 μM 62 ± 6%*, controls 100 ± 9%; *p < 0.05). To determine sunitinib effects on steroidogenesis, we measured steroid hormones in cell culture supernatant by gas chromatography-mass spectrometry. We observed a pronounced decrease of cortisol secretion (1 μM 90.1 ± 1.5%*, 5 μM 57.2 ± 0.3%*, controls 100 ± 2.4%) and a concomitant increase in the DHEA/4-androstenedione and 17-hydroxypregnenolone/17-hydroxyprogesterone ratios, indicating specific inhibition of 3β-hydroxysteroid dehydrogenase (HSD3B2). In yeast microsomes transformed with HSD3B2, no direct inhibition of HSD3B2 by sunitinib was detected. Sunitinib induced down-regulation of HSD3B2 mRNA and protein in ACC cell lines (mRNA: 1 μM 44 ± 16%*; 5 μM 22 ± 2%*; 10 μM 19 ± 4%*; protein: 1 μM 82 ± 8%; 5 μM 63 ± 8%*; 10 μM 55 ± 9%*). CYP11B1 was down-regulated at mRNA but not at protein level and CYP11A1 remained unchanged. In conclusion, target molecules of sunitinib are expressed in the vast majority of ACC samples. Sunitinib exhibits anti-proliferative effects in vitro, and appears to specifically block adrenal steroidogenesis by down-regulation of HSD3B2, rendering it a promising option for treatment of ACC.

Moving toward personalized cell-based interventions for adrenal cortical disorders: part 1--Adrenal development and function, and roles of transcription factors and signaling proteins

Transdifferentiation of an individual's own cells into functional differentiated cells to replace an organ's lost function would be a personalized approach to therapeutics. In this two part series, we will describe the progress toward establishing functional transdifferentiated adrenal cortical cells. In this article (Part 1), we describe adrenal development and function, and discuss genes involved in these processess and selected for use in our pilot studies of transdifferentiation that are presented in the second article (Part 2).

MicroRNA-99a inhibits hepatocellular carcinoma growth and correlates with prognosis of patients with hepatocellular carcinoma

In our in-depth analysis carried out by the Illumina Solexa massive parallel signature sequencing, microRNA-99a (miR-99a) was found to be the sixth abundant microRNA in the miRNome of normal human liver but was markedly down-regulated in hepatocellular carcinoma (HCC). Compelling evidence has suggested the important roles of microRNAs in HCC development. However, the biological function of miR-99a deregulation in HCC remains unknown. In this study, we found that miR-99a was remarkably decreased in HCC tissues and cell lines. Importantly, lower miR-99a expression in HCC tissues significantly correlated with shorter survival of HCC patients, and miR-99a was identified to be an independent predictor for the prognosis of HCC patients. Furthermore, restoration of miR-99a dramatically suppressed HCC cell growth in vitro by inducing the G(1) phase cell cycle arrest. Intratumoral injection of cholesterol-conjugated miR-99a mimics significantly inhibited tumor growth and reduced the α-fetoprotein level in HCC-bearing nude mice. Insulin-like growth factor 1 receptor (IGF-1R) and mammalian target of rapamycin (mTOR) were further characterized as the direct targets of miR-99a. Furthermore, protein levels of IGF-1R and mTOR were found to be inversely correlated with miR-99a expression in HCC tissues. miR-99a mimics inhibited IGF-1R and mTOR pathways and subsequently suppressed expression of cell cycle-related proteins, including cyclin D1 in HCC cells. Conclusively, miR-99a expression was frequently down-regulated in HCC tissues and correlates with the prognosis of HCC patients, thus proposing miR-99a as a prospective prognosis predictor of HCC. miR-99a suppresses HCC growth by inducing cell cycle arrest, suggesting miR-99a as potential tumor suppressor for HCC therapeutics.

Tg737 inhibition results in malignant transformation in fetal liver stem/progenitor cells by promoting cell-cycle progression and differentiation arrest

Cancer stem/progenitor cells (CSPCs) may originate from the malignant transformation of normal stem cells. However, the mechanism by which normal stem cells undergo such transformation is not understood. Our previous studies provided evidence that Tg737 may play an important role in carcinogenesis of liver stem cells. In this study, we investigated the role of Tg737 in the malignant transformation of fetal liver stem/progenitor cells (FLSPCs). We inhibited Tg737 in FLSPCs using short hairpin RNA (shRNA). The microscopic observations of freshly purified Tg737 normal FLSPCs (nFLSPCs) and Tg737-silent FLSPCs (sFLSPCs), which showed high expression levels of stem cell markers, revealed no significant morphological changes in sFLSPCs. Following RNAi of Tg737, the mRNA and protein levels of sFLSPCs decreased by 81.81% and 80.10% as shown by PCR, Western blot and immunocytochemistry analyses. Excluding apoptosis-related effects, we found that silencing of Tg737 resulted in enhanced cell proliferation through promoting cell-cycle progression via upregulation of cyclin D1 and cyclin B expression (P < 0.05). Silencing of Tg737 also resulted in significant arrest of cell differentiation (P < 0.05), stable expression of both albumin (ALB) and alpha fetoprotein (AFP) (P > 0.05) and quiescent ultrastructure. Assessment of cell malignant traits by transwell migration assays and by growth of xenograft tumors in athymic mice showed that reduced expression of Tg737 greatly promoted cell invasion and hepatocarcinogenesis of FLSPCs (P < 0.05). This work shows that inactivation of Tg737 may play an important role in malignant transformation of FLSPCs.

Disease embryo development network reveals the relationship between disease genes and embryo development genes

A basic problem for contemporary biology and medicine is exploring the correlation between human disease and underlying cellular mechanisms. For a long time, several efforts were made to reveal the similarity between embryo development and disease process, but few from the system level. In this article, we used the human protein-protein interactions (PPIs), disease genes with their classifications and embryo development genes and reconstructed a human disease-embryo development network to investigate the relationship between disease genes and embryo development genes. We found that disease genes and embryo development genes are prone to connect with each other. Furthermore, diseases can be categorized into three groups according to the closeness with embryo development in gene overlapping, interacting pattern in PPI network and co-regulated by microRNAs or transcription factors. Embryo development high-related disease genes show their closeness with embryo development at least in three biological levels. But it is not for embryo development medium-related disease genes and embryo development low-related disease genes. We also found that embryo development high-related disease genes are more central than other disease genes in the human PPI network. In addition, the results show that embryo development high-related disease genes tend to be essential genes compared with other diseases' genes. This network-based approach could provide evidence for the intricate correlation between disease process and embryo development, and help to uncover potential mechanisms of human complex diseases.

miR-483-3p controls proliferation in wounded epithelial cells

The mechanisms that regulate keratinocyte migration and proliferation in wound healing remain largely unraveled, notably regarding possible involvements of microRNAs (miRNAs). Here we disclose up-regulation of miR-483-3p in 2 distinct models of wound healing: scratch-injured cultures of human keratinocytes and wounded skin in mice. miR-483-3p accumulation peaks at the final stage of the wound closure process, consistent with a role in the arrest of "healing" progression. Using an in vitro wound-healing model, videomicroscopy, and 5-bromo-2'-uridine incorporation, we observed that overexpression of miR-483-3p inhibits keratinocyte migration and proliferation, whereas delivery of anti-miR-483-3p oligonucleotides sustains keratinocyte proliferation beyond the closure of the wound, compared with irrelevant anti-miR treatment. Expression profiling of keratinocytes transfected with miR-483-3p identified 39 transcripts that were both predicted targets of miR-483-3p and down-regulated after miR-483-3p overexpression. Luciferase reporter assays, Western blot analyses, and silencing by specific siRNAs finally established that kinase MK2, cell proliferation marker MKI67, and transcription factor YAP1 are direct targets of miR-483-3p that control keratinocyte proliferation. miR-483-3p-mediated down-regulation of MK2, MKI67, and YAP1 thus represents a novel mechanism controlling keratinocyte growth arrest at the final steps of reepithelialization.

Toward a pathway-centered approach for the treatment of adrenocortical carcinoma

PURPOSE OF REVIEW

Adrenocortical carcinoma is an aggressive, lethal malignancy of the adrenal cortex. The rarity of the disease has stymied therapeutic development. Recent work toward understanding the molecular pathogenesis of the disease has identified several potential new diagnostic and therapeutic targets.

RECENT FINDINGS

The molecular characterization of adrenocortical carcinoma has identified dysregulation of the Gap 2/mitosis transition and the insulin-like growth factor 1 receptor signaling cascade as two major pathways for therapeutic development. These studies have also highlighted an unappreciated heterogeneity of the disease at the gene level that nevertheless seems to converge onto common cellular pathways. Additionally, the characterization of Wnt signaling through β-catenin in adrenal development, the demonstration of the involvement of BMP signaling in adrenocortical carcinoma growth regulation, and the discovery that ERCC1 expression levels can predict therapeutic response to platinum are just a few of the recent advances that promise to shed light on adrenocortical carcinoma biology.

SUMMARY

Short-term, therapeutic development should target the Gap 2/mitosis transition and the downstream signaling of the insulin-like growth factor 1 receptor receptor. Long-term, additional characterization of patient samples, particularly at the sequence level, is required to fully understand adrenocortical carcinoma biology and apply that knowledge to clinical practice.

mRNA and microRNA expression patterns in adrenocortical cancer

Adrenocortical cancer is a rare tumor and its prognosis is poor. Although numerous tumor-associated genetic and signal transduction alterations have been described to date, its pathogenesis is still unclear. Hybridization-based DNA microarray approaches may reveal significant gene expression alterations and may thus contribute to a better understanding of tumorigenesis and may identify molecular markers applicable for the distinction of benign and malignant lesions. Beside gene expression patterns, studies on microRNAs seem to be useful, as well. Novel therapeutical targets might be established by these approaches. In this review, the authors attempt to summarize the main findings of mRNA and microRNA expression microarray studies performed to date in adrenocortical cancer including a recent meta-analysis of gene expression data and present novel pathogenic pathways.

Genetics and genomics of childhood adrenocortical tumors

Adrenocortical tumors in children are usually diagnosed because of signs of virilization and their prognosis is poor. They possess several distinct pathological features compared to adrenocortical tumors in adults and have an exceptional prevalence in southern Brazil, where they are nearly invariably linked to the presence of a germline specific TP53 (R337H) mutation. Other important factors in childhood adrenocortical tumor pathogenesis are overexpression of the Steroidogenic Factor-1 transcription factor and imprinting defects in the 11p15 genomic region, causing overexpression of Insulin-like Growth Factor-2. Genomic studies have revealed the prognostic relevance of the expression of some Major Histocompatibility Complex genes and the deregulation of the Insulin-like Growth Factor/mammalian Target Of Rapamycin pathway by microRNAs in these tumors. Our hope is that these findings will constitute the basis for the development of novel therapies that will be more active against these tumors and less toxic for the patients.