The plasma levels of miR-24-3p, miR-16-5p, miR-185-5p, and miR-451a were upregulated during noise exposures, and increased levels of miR-21 have been found in vestibular schwannomas and human cholesteatoma.
Considering the function of miR‑21 in the regulation of proliferation and apoptosis, let‑7a may control cell proliferation and apoptosis by regulating miR‑21, and its targets, in cholesteatoma keratinocytes.
It is possible that upregulation of miR-21 leads to higher tumour cell proliferation and invasion of cholesteatoma in children than adults, and the benign nature of cholesteatoma may be due to a balance between let-7a microRNA and miR-21.
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.