The levels of retinoid RARβ receptors correlate with galectin-1, -3 and -8 expression in human cholesteatomas

Abstract

Cholesteatoma is a benign disease characterized by the presence of an unrestrained growth and the accumulation of keratin debris in the middle ear cavity. This often recurs, even when surgical resection is thought to be complete. In a previous study we showed that cholesteatomas with the highest apoptotic indices recurred more rapidly and also exhibited a high level of p53 immunopositive cells. In view of their relevance to the characterization of the cell differentiation status, the present study focuses on the expression of retinoid acid receptors (RARs) and galectins in human cholesteatomas. Retinoids control the differentiation processes in keratinocytes while galectins play strikingly modulatory roles at apoptosis and cell adhesion levels in a wide variety of tissue (embryonic, normal and neoplastic). To clarify the expression of these two protein families in human cholesteatomas we examined and quantified the levels of immunohistochemical expression of RARα, β and γ, and also galectin-1, -3 and -8 in a series of 70 human cholesteatomas. Our data show clearly that predominantly RARβ and galectin-1 were expressed. The RARγ concentration was significantly lower than that of the RARα; this was also observed for the galectin-8 concentration in comparison with the galectin-3 one. Furthermore, the level of RARβ expression correlated highly ( P=0.00001) with the level of galectin-8 expression, which also correlated significantly with the level of RARα and RARγ expression. In addition, this parameter also correlated with the level of galectin-1 and galectin-3 expression. These data suggest that cholesteatomas may originate in an undifferentiated population of keratinocytes, and that a relation may exist between retinoid activity and galectins.