Immunohistochemical evaluation of Ki-67 and GLI1 in sporadic and nevoid basal cell carcinoma syndrome-associated odontogenic keratocysts.

INTRODUCTION: Odontogenic keratocyst (OKC) is a developmental odontogenic cyst that may occur sporadically (OKCsp) or in association with nevoid basal cell carcinoma syndrome (NBCCS) (OKC-sy). NBCCS is an autosomal dominant disorder characterised by morphological abnormalities and an increased predisposition to several neoplasms, including basal cell carcinomas. Mutations in the tumour suppressor gene PTCH1 have been reported in patients with OKC and NBCCS. PTCH1 participates in a signalling cascade that culminates in the translocation of GLI transcription factors to the nucleus, thereby activating target genes involved in cell proliferation. Aberrant GLI1 expression has been associated with increased proliferation in lung adenocarcinoma and other cancers.

OBJECTIVE: To compare GLI1 and Ki-67 protein expression in OKCs associated with NBCCS versus sporadic OKCs.

MATERIALS AND METHODS: We included 13 OKCsp and 9 OKCsy from a children's hospital and a dental school. Immunohistochemistry was performed using anti-GLI1 and anti-Ki-67 to assess GLI1 expression and cell proliferation.

RESULTS: No significant differences were observed in GLI1 or Ki-67 expression in the epithelial component of OKCsy versus OKCsp. A positive correlation between GLI1 and Ki-67 expression was detected in the total sample (r=0.71, p<0.05).

CONCLUSION: The positive correlation between GLI1 and Ki-67 expression in OKCs suggests an association between SHH pathway activity and cell proliferation in both sporadic and syndromic lesions.