Analysis of p53 protein by PAb240, Ki-67 expression and human papillomavirus DNA detection in different types of odontogenic keratocyst.

OBJECTIVE: To investigate the possible association between alterations in the p53 system and human papillomavirus (HPV) infection in the etiology of odontogenic keratocysts (OKCs) and to study proliferation and epithelial maturation patterns by topographic analysis of Ki-67 expression. MATERIALS AND METHODS: Eighty-three OKC samples (29 cases associated with nevoid basal cell carcinoma syndrome, 29 solitary non-recurrent cases 20 solitary recurrent cases, and 5 chondroid keratocysts) were studied by immunohistochemistry to detect p53 protein (PAb 244) and Ki-67 (MIB-1) expression, and by PCR to detect HPV DNA. RESULTS: Twelve cases (14.6%) expressed p53 protein; no case showed the presence of HPV DNA; 9 cases (11%) presented with mild epithelial dysplasia. The suprabasal expression of Ki-67 was significantly more frequent than its basal expression (p < 0.001). p53 protein expression was significantly associated with the presence of epithelial dysplasia (p = 0.023). Ki-67 expression was not associated with OKC type, the presence of dysplasia, or p53 expression. CONCLUSION: HPVs do not participate in the etiology of OKC, and it appears unlikely that a p53 gene mutation mechanism plays a major role in the genesis of OKC. OKCs show proliferation and genuine maturation behavior reminiscent of benign neoplasms with local destructive capacity.

Adhesion molecule CD44 expression in non-tumor epithelium adjacent to laryngeal cancer.

BACKGROUND: Studies of adjacent non-tumor epithelia (ANTE) of laryngeal cancer have presented contradictory results regarding the expression of the adhesion molecule CD44 and its role as an early event and risk marker for progression to cancer. METHODS: An immunohistochemical study was performed on changes in CD44 expression in the ANTE and tumor tissue of 112 cases of laryngeal cancer, using the anti-CD44 monoclonal antibody DF1485. The aim was to evaluate the importance of these changes as an early event in laryngeal carcinogenesis. RESULTS: The ANTE were histologically hyperplastic in 107 cases (95.5%) and presented epithelial dysplasia in 105 cases (93.7%). A significant association between tumor and epithelial CD44 expression was observed in both hyperplastic (p < 0.001) and dysplastic (p < 0.001) ANTE. There was no significant association between ANTE CD44 expression and clinical or histopathological relevant data. CONCLUSIONS: Loss of CD44 expression in ANTE can be considered an early event in laryngeal carcinogenesis and a marker of major alterations in CD44 expression in the derived tumor tissue.