The Role of miR-200b-3p in Targeting PTHrP in the Pathogenesis of Bone Destruction in Cholesteatoma.

OBJECTIVE

To elucidate the mechanism underlying the involvement of miR-200b-3p in the bone destruction in cholesteatoma.

METHODS

Expression levels of miR-200b-3p, parathyroid hormone-related protein (PTHrP), and receptor activator for nuclear factor-kappa B ligand (RANKL) in cholesteatoma and normal skin of the external auditory canal were examined. HaCaT cells were transfected with miR-200b-3p mimic, miR-200b-3p mimic NC, miR-200b-3p inhibitor, and miR-200b-3p inhibitor NC. Meanwhile, RAW264.7 cells were cultured with RANKL and PTHrP + RANKL combined intervention. A bone resorption lacunae experiment was performed to assess the bone absorption function of the osteoclasts.

RESULTS

The expression level of miR-200b-3p significantly decreased in cholesteatoma and was obviously correlated with the degree of bone destruction. However, the expression levels of PTHrP and RANKL significantly increased. An upregulation of miR-200b-3p expression in the miR-200b-3p mimic group of HaCaT cells was observed, accompanied by a significant downregulation of PTHrP expression. The miR-200b-3p inhibitor group showed downregulated miR-200b-3p expression and significantly upregulated PTHrP expression, suggesting a negative regulatory effect of miR-200b-3p on PTHrP expression. Scanning electron microscopic analysis of the bone resorption lacunae revealed a significant increase in the number and size of bone resorption lacunae in the PTHrP + RANKL combined intervention group compared to those in the RANKL intervention group.

CONCLUSION

MiR-200b-3p was underexpressed in cholesteatoma, resulting in the upregulation of PTHrP secreted by keratinocytes, activation of the downstream RANKL pathway, and promotion of differentiation of monocyte macrophages in the cholesteatoma perimatrix into osteoclasts, thus contributing to bone destruction in cholesteatoma.

LEVEL OF EVIDENCE: N/A.