Proliferación y apoptosis en epitelio lingual de ratones con tumores salivales inducidos por dimetilbenzantraceno (DMBA) y modulados por lípidos dietarios. / [Proliferation and apoptosis in tongue epithelium of mice bearing salivary tumors induced by dimetilbenzantraceno (DMBA) and modulated by dietary lipids]

ABSTRACT

INTRODUCTION: According to the concept of field defects during the carcinogenesis process, excessive epithelial proliferation/apoptosis may exist in areas near tumors. Proliferation or apoptosis could be modified by dietary lipids. PURPOSE: The present study was designed to analyze proliferation and apoptosis in tongue epithelium of mice fed diets based on different lipids followed by induction of salivary tumors with DMBA. MATERIALS AND METHODS: Forty-five days after weaning, ten BALB/c mice were assigned to two diets corn oil (CO) and fish oil (cod liver, FO). Two weeks later, DMBA was injected in the submandibular area. Animals were sacrificed at the 13th post-injection week. Samples of tongue were fixed in formalin-ethanol and immunohistochemically stained for proliferation (Ki-67) and apoptosis (Bax). By light microscopy, the number of nuclei positive for these markers were counted out of three-hundred total interphase cells both in dorsal and in ventral tongue surfaces. Results were analyzed through Analysis of Variance and t Test. RESULTS: Cell proliferation was greater in dorsal than in ventral tongue surfaces (p < 0.0001) with no diet difference. Apoptosis was significantly greater in mice fed FO than CO, particularly in tongue dorsal epithelia (p < 0.018). CONCLUSIONS: This study shows that FO diet induces higher levels of apoptosis in tongue epithelia suggesting a tissue defensive mechanism when exposed to a carcinogenic-tumoral agent.