Expression of the antiapoptotic proteins clusterin and Bcl-2 in laryngeal squamous cell carcinomas

Bcl-2 and clusterin genes have been related to the inhibition of apoptosis, an event that plays a key role in malignant transformation and in invasive disease. In this work, we determine the significance of clusterin and bcl-2 expression in a large series of laryngeal carcinomas. We used immunohistochemical methods and in situ hybridization to examine the expression of these proteins. Non-tumoral epithelial laryngeal tissues did not express clusterin and bcl-2 proteins. However, 9% (14 out of 154) and 25% of these tumors (39 of 154) had positive clusterin and bcl-2 staining, respectively. Clusterin expression was significantly related to the degree of local invasion and higher bcl-2 expression was found in these clusterin-positive tumors (p < 0.05). Bcl-2 expression was significantly correlated with supraglottic localization, nodal metastases, invasion in depth, and poorly differentiated tumors. However, by multivariate analysis, bcl-2 was shown to be an independent predictor of good prognosis in these tumors (OR = 0.12, 95% CI = 0.02-0.91). These findings indicate that clusterin and bcl-2 are upregulated in laryngeal carcinomas and their expression is related to the invasiveness of these tumors.