Chromosomal imbalances are associated with increased proliferation and might contribute to bone destruction in cholesteatoma

Circular RNA profile in Graves' disease and potential function of hsa_circ_0090364

Background

Graves' disease is a common autoimmune disease. Cytokines and their signalling pathways play a major part in the pathogenesis of Graves' disease; however, the underlying mechanism needs to be clarified.

Aims

The aim of this study was to explore whether circular RNAs participate in the immunological pathology of Graves' disease via cytokine-related signalling pathways.

Methods

Bioinformatics analysis was performed to identify differentially expressed circular RNAs and their targets and associated pathways. A total of three patients with Graves' disease and three sex- and age-matched healthy controls were enrolled for validation with microarray analysis and real-time quantitative PCR (qPCR). An additional 24 patients with Graves' disease and 24 gender- and age-matched controls were included for validation by real-time fluorescent qPCR. Flow cytometry and CCK8 assays were used to detect the apoptotic and proliferative levels of Jurkat cells (T lymphocytes) with the silenced expression of circRNA. ELISA was performed to detect the growth and apoptosis-related proteins. The competition mechanism of endogenous RNA was explored by real-time fluorescence qPCR.

Results

A total of 366 significantly differentially expressed circular RNAs were identified in the Graves' disease group compared to healthy controls. The level of hsa_circ_0090364 was elevated in Graves' disease patients and positively correlated with thyroid-stimulating hormone receptor antibodies. Further analyses suggested that hsa_circ_0090364 may regulate the JAK-STAT pathway via the hsa-miR-378a-3p/IL-6ST/IL21R axis to promote cell growth.

Conclusions

These results provide novel clues into the pathophysiological mechanisms of Graves' disease and potential targets for drug treatment.

Comprehensive circular RNA expression profiling with associated ceRNA network reveals their therapeutic potential in cholesteatoma

Cholesteatoma is a chronic disease that pathologically displays a benign tumor with excessive squamous epithelial cell proliferation in the middle ear. Clinically, however, it can manifest malignant behavior by destroying adjacent tissues and organs. Although previous studies have demonstrated that the pathogenesis of cholesteatoma is correlated with epigenetic dysregulation, the exact mechanism remains unclear. Circular RNAs (circRNAs) have been revealed as being abundantly expressed in various organisms and have been found to contribute to the regulation of many diseases. To date, no reports have elucidated their expression profiles and functions in cholesteatoma. In the present study, the circRNA expression profile in cholesteatoma was explored for the first time by using microarray analysis. We obtained a total of 355 significantly differentially expressed circRNAs in cholesteatoma, among which 101 were identified to be upregulated and 254 downregulated. By constructing circRNA‑lncRNA‑miRNA‑mRNA competing endogenous RNA (ceRNA) network, it was discovered that circRNAs may function as ceRNAs and contribute to the formation of cholesteatoma. These results provide novel insight into the pathogenesis of cholesteatoma and suggest circRNAs as potential promising therapeutic targets for cholesteatoma.

Analysis of KRT1, KRT10, KRT19, TP53 and MMP9 expression in pediatric and adult cholesteatoma

Cholesteatoma is an epidermal cyst with still unknown pathomechanism. The aim of the current study was to investigate molecular differences in the background of the hyperproliferative property and aggressive behavior typical of the cholesteatoma epithelium. The expression of three cytokeratin genes (KRT1, KRT10 and KRT19), the matrix metalloproteinase 9 gene (MMP9) and the tumor suppressor TP53 gene was measured by qRT-PCR in surgical samples of pediatric and adult cholesteatoma cases and their expression level was compared to that of normal skin samples from the retroauricular region of control individuals. Cholesteatoma samples were stratified according to the age of onset and recurrence for more detailed analysis. Our results showed identical expression pattern for KRT1 and KRT10, their expression was higher in pediatric cases than in adults, especially in pediatric recurrent samples. The expression level of KRT19 was inversely proportional to that of KRT1/KRT10, it was lower in the more invasive recurrent cases both in our pediatric and adult groups. As it was expected from the bone destructive behavior of cholesteatoma, a significantly elevated expression of MMP9 was measured in cholesteatoma samples, the highest level was found in adult recurrent cases. Low expression levels characterize the TP53 gene without significant differences in our samples. These findings demonstrate that cytokeratin expression distinguishes between pediatric/adult, nonrecurrent/recurrent cases, suggesting that distinct differentiation state and cell division potential characterize these cholesteatoma cases. KRT19 with a tumor suppressor potential might restrict the recurrence of cholesteatoma. The differences observed in gene expression profiles between cholesteatoma and control samples support the notion that cholesteatoma is a cystic lesion with tumor-like behavior because it is characterized by invasive, destructive growth and high tendency for recurrence.

Neoplasia in Cri du Chat Syndrome from Italian and German Databases

Cri du Chat syndrome (CdC) is a chromosomal abnormality (deletion of short arm of chromosome 5) associated with intellectual disability and typical anatomical abnormalities. Research up to now focuses on the management of the disease during childhood. The longer lifespan of these patients warrants deeper investigations of how and if aging could be affected by the syndrome. We decided to focus on the association of the disease with proliferative disorders. Data on proliferative disorders in a cohort of 321 patients from Italian and German Cri du Chat databases were collected. A neoplasia was present in four patients (age 10–50 yrs), and a fifth patient developed a cholesteatoma during childhood. It is of interest that two cases had an early onset of the neoplasia as compared to the expected age of development in the general population. The chromosome region deleted in 5p does not contain genes whose haploinsufficiency is a well-known main cause of the proliferative disorders observed. We nonetheless believe that reporting even sporadic cases of proliferative disorders in CdC patients may increase our knowledge as to the natural history of the disease. In conclusion, available information suggests that surveillance for cancer development in CdC can follow the guidelines for the general population.

Updates and knowledge gaps in cholesteatoma research

The existence of acquired cholesteatoma has been recognized for more than three centuries; however, the nature of the disorder has yet to be determined. Without timely detection and intervention, cholesteatomas can become dangerously large and invade intratemporal structures, resulting in numerous intra- and extracranial complications. Due to its aggressive growth, invasive nature, and the potentially fatal consequences of intracranial complications, acquired cholesteatoma remains a cause of morbidity and death for those who lack access to advanced medical care. Currently, no viable nonsurgical therapies are available. Developing an effective management strategy for this disorder will require a comprehensive understanding of past progress and recent advances. This paper presents a brief review of background issues related to acquired middle ear cholesteatoma and deals with practical considerations regarding the history and etymology of the disorder. We also consider issues related to the classification, epidemiology, histopathology, clinical presentation, and complications of acquired cholesteatoma and examine current diagnosis and management strategies in detail.

Etiopathogenesis of acquired cholesteatoma: prominent theories and recent advances in biomolecular research

OBJECTIVE

To review recent biomolecular advances in etiopathogenesis of acquired cholesteatoma.

DATA SOURCES

MEDLINE via OVID (to March 2014) and PubMed (to March 2014).

REVIEW METHODS

All articles referring to etiopathogenesis of acquired cholesteatoma were identified in the above databases, from which 89 articles were included in this review.

RESULTS

The mechanisms underlying the etiopathogenesis of acquired cholesteatoma remain a subject of competing hypotheses. Four theories dominate the debate, including theories of invagination, immigration, squamous metaplasia, and basal cell hyperplasia. However, no single theory has been able to explain the clinical characteristics of all cholesteatoma types: uncoordinated hyperproliferation, invasion, migration, altered differentiation, aggressiveness, and recidivism. Modern technologies have prompted a number of researchers to seek explanations at the molecular level. First, cholesteatomas could be considered an example of uncontrolled cell growth, capable of altering the balance toward cellular hyperproliferation and enhancing the capacity for invasion and osteolysis. Second, the dysregulation of cell growth control involves internal genomic or epigenetic alterations and external stimuli, which induce excessive host immune response to inflammatory and infectious processes. This comprises several complex and dynamic pathophysiologic changes that involve extracellular and intracellular signal transduction cascades.

CONCLUSIONS

This article summarizes the existing theories and provides conceptual insights into the etiopathogenesis of acquired cholesteatoma, with the aim of stimulating continued efforts to develop a nonsurgical means of treating the disorder.

The c-MYC protooncogene expression in cholesteatoma

Cholesteatoma is an epidermoid cyst, which is most frequently found in the middle ear. The matrix of cholesteatoma is histologically similar to the matrix of the epidermoid cyst of the skin (atheroma); their epithelium is characterized by hyperproliferation. The c-MYC protooncogene located on chromosome 8q24 encodes a transcription factor involved in the regulation of cell proliferation and differentiation. Previous studies have found aneuploidy of chromosome 8, copy number variation of c-MYC gene, and the presence of elevated level c-MYC protein in cholesteatoma. In this study we have compared the expression of c-MYC gene in samples taken from the matrix of 26 acquired cholesteatomas (15 children and 11 adults), 15 epidermoid cysts of the skin (atheromas; head and neck region) and 5 normal skin samples (retroauricular region) using RT-qPCR, providing the first precise measurement of the expression of c-MYC gene in cholesteatoma. We have found significantly elevated c-MYC gene expression in cholesteatoma compared to atheroma and to normal skin samples. There was no significant difference, however, in c-MYC gene expression between cholesteatoma samples of children and adults. The significant difference in c-MYC gene expression level in cholesteatoma compared to that of atheroma implies a more prominent hyperproliferative phenotype which may explain the clinical behavior typical of cholesteatoma.

Acquired cholesteatoma pathogenesis: stepwise explanations

BACKGROUND

Since Virchow's first, 1855 publication on cholesteatoma, this disease has been the subject of extensive debate. The pathogenesis of acquired cholesteatoma is repeatedly explained on the premises of the migration, hyperplasia and metaplasia theories, but proof for the latter theory remains limited. In retrospect, there is progress toward better understanding of all the pathological mechanisms involved, as expounded in this review.

DISCUSSION

The triggers for cholesteatoma onset are diverse, and may involve tympanic membrane trauma (i.e. perforation, displacement, retraction or invagination), tympanic membrane disease, and/or tympanic cavity mucosa disease. Research has revealed that cell migration is replaced under inflammatory conditions by hyperplasia, which triggers the onset of cholesteatoma. Lately, the hyperplasia theory gained prominence and circumscription of the papillary cone formation concept provided insight into cholesteatoma progression (growth and expansion). Diseased mucosa can contribute to the development of retraction pockets and cholesteatoma. The type of cholesteatoma trigger and the role of chronic inflammation during disease progression and recurrence are important in guiding clinical intervention.