Experimental Study on TGF-beta1 Gene Expression in Cholesteatoma

Park, Chul Won; Jang, Young Ho; Tae, Kyung; Kim, Sun Kon; Lee, Kyung Chul

Abstract

Cholesteatoma is composed of hyperproliferative keratinizing epithelium in the middle ear cavity. Its pathogenesis of destruction is not clear, and thus many theories such as pressure effect of cholesteatoma, enzymatic destruction from monocyte, cytokines including interleukin, tumor necrosis factor, and etc, are reported. Recently, several cytokines, tumor necrosis factor-alpha(TNF-alpha) and beta(TNF-beta), epithelial growth factor(EGF), transforming growth factor-beta(TGF-beta), interleukin-1(IL-1) and 6(IL-6), were immunolocalized in cholesteatoma. Of these, overexpression of EGF, TNF-alpha, IL-1 and 6 in cholesteatoma tissue have been suggested to correlate with bony destruction, but TGF-beta has been hypothesized to correlate with osteoclast inhibitory function. Here, to examine the potential role of TGF-beta in the pathogenesis of cholesteatoma and its bone destruction, I investigated gene expression in cholesteatoma tissue as well as in the normal postaural skin using RT-PCR(reverse transcription-polymerase chain reaction) technique, and obtained the following results. 1) In 13 cases of cholesteatoma, TGF-beta1 band was expressed at 474bp size marker site in 12 cases, while in 13 cases of normal postaural skin it expressed in 8 cases. 2) All of 12 cases which were expressed TGF-beta1 had granulation tissue and in 9 cases, there were bone destruction, but there was no granulation tissue and bone destruction in one case which was not espressed TGF-beta1. 3) In all cases of over 1 year disease history, TGF-beta1 expression were noted. However, in cases of under 1 year disease history, there was no expression. In conclusion, the higher expression of TGF-beta1 in cholesteatoma than normal postaural skin suggest that TGF-beta1 plays a major role in proliferation and growth of cholesteatoma as well as protective effect for bone destruction by cholesteatoma. But quantative test will be needed to clarify this point.