Survival signaling and terminal differentiation in cholesteatoma epithelium

Immunohistochemical Identification and Assessment of the Location of Immunoproteasome Subunits LMP2 and LMP7 in Acquired Cholesteatoma

Cholesteatoma, accompanied by chronic inflammatory response, is characterized by invasive growth and osteolytic activity. As specific proteasome isoforms, the immunoproteasomes serve as an important modulator of inflammatory responses. The aim of the present study was to determine the biological activity of cholesteatoma through the analysis of the expression and localization of immunoproteasome subunits of low molecule weight protein (LMP) 2 and LMP7. Cholesteatoma specimens were obtained from 15 adults who underwent ear surgery due to acquired attic cholesteatoma. Normal skin specimens were taken from retro-auricular skin incisions from the same patients. The specimens were stained with anti-LMP7 antibody, using immunohistochemistry techniques based on the binding of biotinylated secondary antibody with the enzyme-labeled streptavidin and the Envision FLEX system. In all specimens of cholesteatoma, the immunohistochemical reaction with the antibody against the LMP2 was positive, in both the cytoplasm of the cholesteatoma matrix and the perimatrix. A negative reaction with anti-LMP2 was observed in the cytoplasm and nuclei of control skin cells. A positive nuclear and cytoplasmic immunohistochemical reaction with anti-LMP7 has been demonstrated in numerous cells, in both the matrix and perimatrix of cholesteatoma. We present evidence of the presence of expressions of LMP2 and LMP7 within cholesteatoma tissue. Our results might bring new information concerning immunoproteasome-dependent pathophysiologic mechanisms in cholesteatoma.

Expression and Regulatory Mechanisms of MicroRNA in Cholesteatoma: A Systematic Review

Cholesteatoma is a temporal bone disease characterized by dysfunctions of keratinocytes. MicroRNAs (miRNAs) are evolutionary conserved noncoding RNAs that regulate mRNA expression. They can be packaged into exosomes and transported to target cells that can be used in the future therapy of cholesteatoma. This study aimed to collect knowledge on the role of miRNAs and exosomal miRNAs in cholesteatoma and was conducted according to the PRISMA guidelines for systematic reviews. Four databases were screened: Pubmed/MEDLINE, Web of Science, Scopus, and the Cochrane Library. The last search was run on the 6th of June 2023. We included full-text original studies written in English, which examined miRNAs in cholesteatoma. The risk of bias was assessed using the Office of Health Assessment and Translation (OHAT) Risk of Bias Rating Tool, modified for the needs of this review. We identified 118 records and included 18 articles. Analyses revealed the downregulation of exosomal miR-17 as well as miR-10a-5p, miR-125b, miR-142-5p, miR34a, miR-203a, and miR-152-5p and the overexpression of exosomal miR-106b-5p as well as miR-1297, miR-26a-5p, miR-199a, miR-508-3p, miR-21-3p, miR-584-5p, and miR-16-1-3p in cholesteatoma. The role of differentially expressed miRNAs in cholesteatoma, including cell proliferation, apoptosis, the cell cycle, differentiation, bone resorption, and the remodeling process, was confirmed, making them a potential therapeutic target in this disease.

Biomarkers in Otorhinolaryngology

Biomarkers of otorhinolaryngologic diseases with higher insult over a person’s him/herself and overall health services are summarized in brief. In order to define, diagnose, treat and monitor any disease markers are needed. Otorhinolaryngology (ORL) is interested in special disease entities of the region besides otorhinolaryngologic involvements of the systemic diseases and unique forms of pathologies such as cholesteatoma, Meniere’s disease and otosclerosis. Neoplasia is another heading to deal with. In the following chapter, one will find an overview of molecules that have been used as a biomarker as well as the end points of the present research on the issue relevant with ORL. Day by day, new molecules are being named however, the pathways of action are rather the same. Readers will find the headings related to the most common diseases of the field, informing them about where to look for defining new strategies of understanding of each disease.

Non-coding RNA and cholesteatoma

OBJECTIVE

Cholesteatoma is a challenging chronic pathology of the middle ear for which pharmacologic therapies have not been developed yet. Cholesteatoma occurrence depends on the interplay between genetic and environmental factors while master regulators orchestrating disease progression are still unknown. Therefore, in this review, we will discuss the diagnostic and therapeutic potential of non-coding RNAs (ncRNA) as a new class of regulatory molecules.

METHODS

We have comprehensively reviewed all articles investigating ncRNAs, specifically micro RNAs (miRNAs) and long ncRNAs (lncRNA/circRNA) in cholesteatoma tissue.

RESULTS

Candidate miRNA approaches indicated that miR-21 and let-7a are the major miRNAs involved in cholesteatoma growth, migration, proliferation, bone destruction, and apoptosis. Regulatory potential for the same biological processes was also observed for miR-203a. The NF-kB/miR-802/PTEN regulatory network was in relation to observed miR-21 activity in cholesteatoma as well. High throughput approaches revealed additional ncRNAs implicated in cholesteatoma pathology. Competitive endogenous RNA (ceRNA) analysis highlighted lncRNA/circRNA that could be "endogenous sponge" for miR-21 and let-7a based on the hypothesis that RNA transcripts can communicate with and regulate each other by using shared miRNA response elements.

CONCLUSION

In this review, we summarize the discoveries and role of ncRNA in major pathways in cholesteatoma and highlight the potential of miRNA-based therapeutics in the treatment of cholesteatoma.

Level of Evidence: NA.

Ligand-Activated Peroxisome Proliferator-Activated Receptor β/δ Facilitates Cell Proliferation in Human Cholesteatoma Keratinocytes

Cholesteatoma is characterized by both the overgrowth of hyperkeratinized squamous epithelium and bone erosion. However, the exact mechanism underlying the hyperproliferative ability of cholesteatoma remains unknown. In this study, we investigated PPAR β/δ expression in human surgical specimens of cholesteatoma and analyzed its functional role as a regulator of epithelial keratinocyte hyperproliferation. We found that the expression of PPAR β/δ was significantly upregulated in cholesteatoma and ligand-activated PPAR β/δ markedly promoted the proliferation of cholesteatoma keratinocytes. Furthermore, we showed that PPAR β/δ activation increased PDK1 expression and decreased PTEN generation, which led to increased phosphorylation of AKT and GSK3β and increased the expression level of Cyclin D1. Overall, our data suggested that the proliferating effect of PPAR β/δ on the cholesteatoma keratinocytes was mediated by the positive regulation of the PDK1/PTEN/AKT/GSK3β/Cyclin D1 pathway. These findings warranted further investigation of PPAR β/δ as a therapeutic target for recurrent or residual cholesteatoma.

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.

Long noncoding RNAs show differential expression profiles and display ceRNA potential in cholesteatoma pathogenesis

Cholesteatoma is a pathologically benign but clinically destructive middle ear disease, which is caused by excessive epidermal migration and uncontrolled hyperproliferation of keratinocytes of squamous epithelium, leading to various clinical manifestations and serious complications, such as hearing loss, dizziness, facial paralysis, meningitis, and hydrocephalus. However, the pathogenesis of cholesteatoma is still not fully understood. Herein, we performed microarray analysis to identify the differentially expressed patterns of lncRNAs in cholesteatoma for the first time. Our data indicated that compared with matched normal skin tissue, lncRNA expression profiles were significantly altered in cholesteatoma. A total of 787 lncRNAs were identified (fold change ≥2.0, P<0.05), consisting of 181 upregulated and 606 downregulated lncRNAs. Furthermore, by constructing an lncRNA/miRNA/mRNA competing endogenous RNA (ceRNA) network, we found that lncRNAs, such as lncRNA‑uc001kfc.1, had ceRNA potential in cholesteatoma formation. In conclusion, lncRNAs were aberrantly expressed in cholesteatoma compared with normal skin tissues and may play important roles in cholesteatoma formation. Our findings shed novel light on the molecular mechanism of cholesteatoma pathogenesis and suggest that lncRNAs may be potential therapeutic targets for cholesteatoma.

Downregulation of MiR-203a Disinhibits Bmi1 and Promotes Growth and Proliferation of Keratinocytes in Cholesteatoma

Background: Keratinocytes are the predominant cell type in a cholesteatoma, and microRNA (miR)-203a has been shown to be essential for the growth and differentiation of keratinocytes. The regulatory mechanisms of miR-203a and Bmi1-the predicted target of miR-203a that is associated with cholesteatoma-have not been clarified. Methods: Real-time PCR and western blot were carried out for the detection of miRNAs, mRNAs, and proteins, including miR-203a, Bmi1, and phosphorylated (p-)Akt. Immunohistochemical staining was applied to observe the expression and distribution of Bmi1 and of p-Akt in cholesteatoma and in control retroauricular skin. The dual luciferase reporter assay was used to analyze the relationship between miR-203a and Bmi1. Ectopic miR-203a and Bmi1 were transfected into an immortalized line of human keratinocytes (HaCaT cells), and the roles of these molecules in cell proliferation, apoptosis, and migration were explored. Results: Cholesteatoma tissues were characterized by downregulation of miR-203a and concomitant upregulation of Bmi1. Results of the dual-luciferase reporter assay indicated that Bmi1 was a direct target gene of miR-203a. Silencing of miR-203a increased Bmi1 expression; promoted proliferation, colony formation, and migration of HaCaT cells; and inhibited apoptosis. Moreover, p-Akt was significantly increased in cholesteatoma tissues and was positively correlated with Bmi1. Suppression of Bmi1 reduced p-Akt expression in HaCaT cells; subsequent inhibition of miR-203a reversed this phenomenon. Conclusions: Our results reveal that miR-203a may regulate cholesteatoma growth and proliferation by targeting Bmi1. These findings provide insight for the development of novel nonsurgical options for cholesteatoma.

Increased permeability of the epithelium of middle ear cholesteatoma

OBJECTIVE

We investigated the electrical impedance of and the expressions of tight junction molecules in the cholesteatoma epithelium to provide supporting evidence for the acid lysis theory of bone resorption in middle ear cholesteatoma.

METHODS

Study subjects were patients with primary acquired middle ear cholesteatoma and those with non-cholesteatomatous chronic otitis media who underwent tympanomastoidectomy. The electrical impedance of the cholesteatoma epithelium was measured during tympanomastoidectomy by loading alternating currents of 320 Hz and 30.7 kHz. The expressions of tricellulin (MARVELD2), claudin-1 (CLDN1) and claudin-3 (CLDN3) were examined by fluorescence immunohistochemistry and quantitative reverse transcription-polymerase chain reaction.

RESULTS

The electrical impedance of the cholesteatoma epithelium was significantly lower than that of the post-auricular skin and external auditory canal skin at both 320 Hz and 30.7 kHz. Immunoreactivity for MARVELD2, CLDN1 and CLDN3 was localised mainly in the granular layer, and to lesser degree, in the horny and spinous layers in both the cholesteatoma tissue and post-auricular skin. Fluorescence intensity was moderate for MARVELD2, weak for CLDN1 and strong for CLDN3. The expressions of MARVELD2, CLDN1 and CLDN3 mRNA were significantly lower in the cholesteatoma tissue than in the post-auricular skin.

CONCLUSIONS

These results indicate the increased permeability of the cholesteatoma epithelium and suggest that this change is, at least partially, dependent on the decrease in the expressions of the tight junction molecules. This evidence supports the acid lysis hypothesis of bone resorption in cholesteatoma.

Identification of altered protein abundances in cholesteatoma matrix via mass spectrometry-based proteomic analysis

Background

Cholesteatoma are cyst-like structures lined with a matrix of differentiated squamous epithelium overlying connective tissue. Although epithelium normally exhibits self-limited growth, cholesteatoma matrix erodes mucosa and bone suggesting changes in matrix protein constituents that permit destructive behaviour. Differential proteomic studies can measure and compare the cholesteatoma proteome to normal tissues, revealing protein alterations that may propagate the destructive process.

Methods

Human cholesteatoma matrix, cholesteatoma-involved ossicles, and normal middle ear mucosa, post-auricular skin, and non-involved ossicles were harvested. These tissues were subjected to multiplex peptide labeling followed by liquid chromatography and tandem mass spectrometry analysis. Relative protein abundances were compared and evaluated for ontologic function and putative involvement in cholesteatoma.

Results

Our methodology detected 10 764 peptides constituting 1662 unique proteins at 95 % confidence or greater. Twenty-nine candidate proteins were identified in soft tissue analysis, with 29 additional proteins showing altered abundances in bone samples. Ontologic functions and known relevance to cholesteatoma are discussed, with several candidates highlighted for their roles in epithelial integrity, evasion of apoptosis, and immunologic function.

Conclusion

This study produced an extensive cholesteatoma proteome and identified 58 proteins with altered abundances contributing to disease pathopathysiology. As well, potential biomarkers of residual disease were highlighted. Further investigation into these proteins may provide useful options for novel therapeutics or monitoring disease status.

Expression of tumor necrosis factor-like weak inducer of apoptosis in human middle ear cholesteatoma

Tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) was recently identified as a member of the TNF superfamily of structurally related cytokines. It regulates TNF-α and numerous cellular responses. We investigated whether TWEAK is upregulated in human middle ear cholesteatoma compared to the skin of the normal external auditory canal (EAC). The expression of TWEAK was analyzed using reverse transcription-polymerase chain reaction, Western blotting and immunohistochemical staining. TWEAK expression was correlated with that of TNF-α as determined by Western blotting. The expression of TWEAK and TNF-α protein was stronger in cholesteatoma tissue than in EAC skin. TWEAK was expressed to a greater degree in the suprabasal layer in the cholesteatoma than in EAC skin. The expression of TWEAK was correlated more closely with single-stranded DNA than Ki-67 immunohistochemically. These findings imply that TWEAK plays an important role in modulating TNF-α expression and apoptosis in cholesteatoma.

Upregulation of phosphorylated HSP27, PRDX2, GRP75, GRP78 and GRP94 in acquired middle ear cholesteatoma growth

Cholesteatoma is a destructive and expanding growth of keratinizing squamous epithelium in the middle ear or petrous apex. The molecular and cellular processes of the pathogenesis of acquired middle ear cholesteatoma have not been fully understood. In this study, comparative proteomic analysis was conducted to investigate the roles of specific proteins in the pathways regarding keratinocyte proliferation in cholesteatoma. The differential proteins were detected by comparing the two-dimension electrophoresis (2-DE) maps of the epithelial tissues of 12 attic cholesteatomas with those of retroauricular skins. There were 14 upregulated proteins in the epithelial tissues of cholesteatoma in comparison with retroauricular skin. The modulation of five crucial proteins, HSP27, PRDX2, GRP75, GRP78 and GRP94, was further determined by RT-PCR, Western blot and immunohistochemistry. Phosphorylation of HSP27 at Ser-82 was identified by mass spectroscopy. The results of this study suggested that phosphorylated HSP27 is the end expression of two potential signal-transduction pathways, and together with PRDX2, they are very likely involved in the proliferation of keratinocytes in cholesteatoma. Upregulations of GRP75, GRP78 and GRP94 in keratinocytes may be able to counter endoplasmic reticulum stress, to inhibit cell apoptosis, to prevent protein unfolding and to promote cholesteatoma growth.

Acquired cholesteatoma: summary of the cascade of molecular events

BACKGROUND

Cholesteatoma is considered a benign, gradually expanding and destructive epithelial lesion of the temporal bone. The pathogenesis of different classifications of cholesteatoma is marked by similar underlying cellular and molecular processes. Stepwise explanations of the histopathogenesis have been described previously. The current paper focuses on expounding the molecular events of cholesteatoma.

METHOD AND RESULTS

Cholesteatoma pathogenesis encompasses a complex network of signalling pathways during: epidermal hyperplasia, perimatrix-matrix interactions and mucosal disease. This paper presents a review of the molecular events driven by inflammatory mediators and enzymes during: cholesteatoma growth (cell proliferation and apoptosis); maintenance and deterioration (angiogenesis and hypoxia, oxidative stress and toxicity); and complications (bone erosion and hearing loss). The cascade of molecular events applicable to atelectasis and cholesteatoma that coexist with chronic otitis media and bone erosion as sequelae is summarised.

CONCLUSION

The role of lipids in this disease is relatively unexplored, but there is evidence in support of fatty acid role-players that needs confirmation. Future directions in lipid research to delineate molecular mechanisms are proposed.

Institutional review boards and bioethical issues for otologists and audiologists

Otologists and audiologists care for patients and conduct clinical research to find more effective treatments that benefit patients. Institutional Review Board (IRB) permission is necessary for conducting clinical trials on humans. Furthermore, many bioethical conflicts are encountered while conducting research. However, few otologists and audiologists in Korea know bioethics and the principles and regulations of IRBs in detail. This paper reviews the history of ethics in clinical research and current bioethical principles and IRB regulations. We outline what you need as otologists or audiologists to get IRB approval while considering the principles of bioethics.

Cholesteatoma growth and proliferation: posttranscriptional regulation by microRNA-21

OBJECTIVES

The goal of this study was to identify novel regulatory mechanisms controlling the growth and proliferation of cholesteatoma. Specifically, the potential role of microRNAs, regulators of protein translation, was studied in cholesteatoma.

STUDY DESIGN

This study represents a molecular biologic investigation characterizing and comparing microRNA and protein expression in cholesteatoma and normal postauricular skin.

METHODS

Cholesteatoma and normal skin were taken from patients at the time of surgery. Tissue was processed for RNA and protein extraction. Real-time reverse-transcriptase-polymerase chain reaction was used to assess levels of human microRNAs, reverse-transcriptase-polymerase chain reaction was used to confirm the presence of upstream regulators, and Western blot analyses were used to assess levels of downstream target proteins.

RESULTS

Among the microRNAs investigated, human microRNA-21 (hsa-miR-21) showed a 4.4-fold higher expression in cholesteatoma as compared with normal skin (p = 0.0011). The downstream targets of hsa-miR-21, PTEN and programmed cell death 4, were found to be greatly reduced in 3 of 4 cholesteatoma samples. Proposed upstream regulators of hsa-miR-21 expression (CD14, interleukin 6R, gp130, and signal transducer and activator of transcription 3) were present in all cholesteatoma tissues.

CONCLUSION

MicroRNAs represent powerful regulators of protein translation, and their dysregulation has been implicated in many neoplastic diseases. This study specifically identified up-regulation of hsa-miR-21 concurrent with down-regulation of potent tumor suppressor proteins PTEN and programmed cell death 4. These proteins control aspects of apoptosis, proliferation, invasion, and migration. The results of this study were used to develop a model for cholesteatoma proliferation through microRNA dysregulation. This model can serve as a template for further study into potential RNA-based therapies for the treatment of cholesteatoma.

Elevated level of tenascin and matrix metalloproteinase 9 correlates with the bone destruction capacity of cholesteatomas

OBJECTIVES

Bone destruction is a key step in the progression of cholesteatomas. Some of the lesions can grow without affecting the surrounding anatomic structures, whereas others can cause severe bone destruction despite their limited size. This study aims to identify factors that could play important role during the invasion of the disease.

METHODS

Cholesteatoma tissue samples were examined immunohistochemically. Tissue samples were arranged on the basis of bone destruction (destructive cholesteatomas [DC] and nondestructive cholesteatomas [NDC]). Double-immunofluorescent labeling was performed to detect simultaneously 1) tenascin (TN) and cytokeratin; 2) matrix metalloproteinase 9 (MMP-9) and TN; 3) TN and Ki-67. An in situ apoptosis detection kit was used to detect apoptotic cells. External auditory canal skin samples were used as control.

RESULTS

1) In DCs, more widespread stromal TN labeling was seen compared with NDCs or external auditory canal skin samples. 2) More enhanced MMP-9 staining was detected in DCs compared with NDCs. 3) The proportion of Ki-67-positive cells in DC samples was significantly higher than in NDCs. 4) The percentage of apoptotic cells was higher in NDC than in DC samples.

CONCLUSION

Our present study demonstrates that levels of TN, MMP-9, and proliferative activity are increased in cholesteatomas. It has also been shown that increased levels of TN, MMP-9-positive cells, and proliferative activity of the lesions, as well as decreased levels of apoptosis, can be linked to more aggressive clinical behavior of cholesteatomas. Our findings also indicate that TN and MMP-9 can be key molecules of bone destruction during cholesteatoma progression.

Expression of PTEN and phosphorylated Akt in human cholesteatoma epithelium

CONCLUSION

We found a reduced PTEN and an increased phosphorylated Akt (p-Akt) expression in cholesteatoma epithelium when compared with retro-auricular (RA) skin. The negative correlation between cholesteatoma PTEN and p-Akt may suggest that cellular survival mechanisms may be involved in cholesteatoma epithelial hyperplasia.

OBJECTIVES

The tumor suppressor PTEN regulates the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway and modulates cell cycle progression and cell survival. We hypothesized that PTEN might be involved in this pathway mechanism in cholesteatoma.

MATERIALS AND METHODS

Western blotting and immunohistochemistry were used to examine the expression of PTEN and p-Akt in 16 cases of cholesteatoma and paired cases of RA skin.

RESULTS

In cholesteatoma, p-Akt expression was significantly higher than in RA skin, whereas PTEN expression was significantly lower in cholesteatoma when compared with skin (p < 0.05). Immunohistochemical analysis showed that weak PTEN immunoreactivity was observed in the nuclei of cholesteatoma epithelium, whereas strong PTEN immunoreactivity was detected in the nuclei of skin. Also, strong p-Akt immunoreactivity was observed in the cytoplasm of cholesteatoma epithelium, whereas very weak or no p-Akt immunoreactivity was observed in the RA skin. Furthermore, we found that a significant inverse correlation exists between PTEN and p-Akt expression (r = -0.796).

Transforming growth factor beta and wound healing in human cholesteatoma

OBJECTIVE

Cholesteatoma is a nonmalignant, destructive lesion of the temporal bone that gradually expands and causes complications by the erosion of the adjacent bony structures. The consequences can be as severe as facial paralysis and intracranial complications. Until now, surgery has been the only treatment of choice. The pathogenesis of cholesteatoma remains controversial. Current concepts postulate that cholesteatoma may be a wound-healing process, although formal proof is lacking as of yet. Several reports provide evidence for the involvement of transforming growth factor (TGF)beta in both normal and abnormal wound healing.

STUDY DESIGN

The expression of TGFbeta, the activated form of its intracellular effector, phosphorylated-Sma-Mad (pSmad)2, its natural inhibitor, Smad7, and target gene extra domain A-positive fibronectin (EDA-FN) were examined.

METHODS

Quantitative immunohistochemical analysis was performed using an image analysis system.

RESULTS

In 12 cholesteatoma and control samples, protein expressions showed consistent relationships among TGFbeta, nuclear pSmad2, and Smad7. We found concordant expressions of TGFbeta and nuclear pSmad2 in cholesteatoma epithelium and its control. Epithelial Smad7 expression was significantly reduced in cholesteatoma when compared with control epithelium (P = .04). In cholesteatoma extracellular matrix (ECM), a significantly increased TGFbeta, and nuclear pSmad2 was demonstrated (P < .01). Smad7 expression in the ECM was comparable in cholesteatoma and its control. EDA-FN deposition in cholesteatoma ECM was excessive, whereas EDA-FN expression was absent in controls.

CONCLUSION

Our results confirm reports of in vitro experiments and support the concept that cholesteatoma behaves as a chronic wound healing process.