Abstract
Purpose :
Maspin is a protein that belongs to the serine protease superfamily. Several studies have shown controversial results with respect to Maspin expression in cancer. For instance, it is down regulated in some tumors, while it is overexpressed in others, suggesting that maspin may play a diverse role in different cancers. The aim of this study is to evaluate the immunoexpression of maspin in ocular surface squamous neoplasia (OSSN), including conjunctival intraepithelial neoplasia (CIN) and squamous cell carcinoma (SCC).
Methods :
A total of 48 OSSN cases were evaluated for maspin expression using an automated immunohistochemistry process. The OSSN cases included 21 CIN I, 9 CIN II, 6 CIN III, and 12 SCC cases. Nine cases of normal conjunctiva were used as controls. Immunohistochemical expression was assessed based on the intensity and extension of the staining. Intensity was assessed as follows: 0=none, 1=weak, 2=moderate, and 3=strong. Extent was evaluated as the percentage of cells with positive staining (0=none, 1=≤50%, 2=51%-75%, and 3=≥76% of cells). A score ranging between 0-6 was achieved by adding these two semi-quantitative staining parameters. Cases were grouped into two different immunostaining categories: Low immunostaining=score 0-4 and high immunostaining=score 5-6.
Results :
Maspin immunostaining was negative in all control cases of normal conjunctiva and different positive staining levels were found within OSSN group (P=0.04). Furthermore, 19% of CIN I was negative for maspin, while CIN II, CIN III and SCC were all positive. Significantly higher immunostaining levels were detected in SCC compared to CIN I and CIN II (P=0.03). However, no differences were noticed between CIN III and SCC (P=0.5). A direct correlation was found between tumor grade and increased levels of maspin immunostaining (R2=0.64, P=<0.0001).
Conclusions :
Maspin expression increases as cells progress from benign to malignant across the OSSN spectrum. To the best of our knowledge, this is the first study investigating maspin expression in OSSN. Maspin may play an important role in the pathological transformation of CIN into SCC. Further molecular studies are needed to elucidate the exact mechanism underlying the relationship between maspin and OSSN.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.