Peroxisome proliferator-activated receptor gamma expression correlates with the differentiation level of normal, premalignant, and malignant laryngeal squamous cells.

Abstract

Objective: Peroxisome proliferator-activated receptor gamma (PPAR gamma) has been implicated in the differentiation of several cell types, such as adipocytes, monocytes, and epidermal keratinocytes. This study concentrated on PPAR gamma's potential role in the maturation process of laryngeal squamous epithelium, both normal and premalignant, as well as in the differentiation grade of squamous cell carcinomas (SCCs) of the larynx.

Design: A retrospective study.

Setting: A basic research anatomy laboratory, operating within a tertiary care institution.

Materials: Clinical specimens from 89 subjects with normal laryngeal epithelium and hyperplastic, dysplastic, or malignant lesions.

Methods: Paraffin-section immunohistochemistry.

Main outcome measures: Strength and extent of PPAR gamma presence, specified by stain intensity and ratio of stained cells, respectively.

Results: All stratified histologic categories, that is, normal mucosa, hyperplasia, and dysplasia, displayed a significant increase in PPAR gamma expression in suprabasal differentiated layers compared with basal undifferentiated ones (rho < .01). Hyperplasia and dysplasia manifested lower and higher levels of PPAR gamma, respectively, in comparison with normal epithelium. Whereas grade Pi and III SCCs were characterized by equal expression, well-differentiated tumours possessed considerably raised receptor content. Fluctuations of expression among various histologic categories lacked statistical significance, however.

Conclusions: Our results suggest PPAR gamma induction throughout squamous cell differentiation in normal, premalignant, and malignant epithelia.