Cholesteatoma growth and proliferation: posttranscriptional regulation by microRNA-21.
OBJECTIVE
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.


METHODS
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.


CONCLUSIONS
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.
Friedland
David R
DR
Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA. dfriedla@mcw.edu
Eernisse
Rebecca
R
Erbe
Christy
C
Gupta
Nidhi
N
Cioffi
Joseph A
JA
D000328:Adult; D051017:Apoptosis Regulatory Proteins / Q000096:biosynthesis / Q000235:genetics; D049109:Cell Proliferation; D002781:Cholesteatoma / Q000378:metabolism / Q000473:pathology; D004423:Ear / Q000473:pathology / Q000502:physiology; D006801:Humans; D018950:Lipopolysaccharide Receptors / Q000096:biosynthesis / Q000235:genetics; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism; D051059:PTEN Phosphohydrolase / Q000096:biosynthesis / Q000235:genetics; D012323:RNA Processing, Post-Transcriptional; D016601:RNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D019947:Receptors, Interleukin-6 / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050796:STAT3 Transcription Factor / Q000096:biosynthesis / Q000235:genetics; D012867:Skin / Q000378:metabolism / Q000473:pathology; D015854:Up-Regulation
D051017:Apoptosis Regulatory Proteins; D018950:Lipopolysaccharide Receptors; C524940:MIRN21 microRNA, human; D035683:MicroRNAs; C114487:PDCD4 protein, human; D016601:RNA-Binding Proteins; D019947:Receptors, Interleukin-6; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human