Expression of CD44 variant isoforms and association to the benign form of endocrine pancreatic tumours

Background: The expression of CD44 and its isoforms have been shown in many neoplastic tissues to serve as prognostic indicators, therefore, the feasibility of using these as prognostic markers in endocrine pancreatic tumour patients was examined. Patients and methods: Immunohistochemistry (IHC) was performed on 26 tumour samples (5 gastrinomas, 3 glucagonomas, 10 non-functioning tumours, 6 insulinomas, 2 mixed insulinoma and glucagonomas) with monoclonal antibodies against CD44s (standard form) and variant isoforms (v4, v5, v6, v7, v7-8, v9, v10). Staining was correlated to the tumour proliferation, malignancy, metastasis and patients survival. Results: There was variable expression of CD44s. All tumours showed complex expression of many isoforms. CD44v6 and CD44v9 were down regulated in malignant tumours. There was statistical significance of CD44v6 expression in benign tumours (P < 0.05) compared to malignant tumours and near significance in CD44v9 expression (P = 0.0574). Survival of the patients with CD44v6 positive staining was higher than those who were negative (P = 0.0822). Moreover, the expression was well correlated to the patients without any distant metastases (CD44v6, p < 0.001; CD44v9, P < 0.01). Tumour proliferation (Ki67 index) correlated directly to the malignancy (P < 0.05) and there was inverse correlation between Ki67 index and CD44v6 (P < 0.05) as well as v9 (P < 0.05). Conclusions: Endocrine pancreatic tumours express CD44s and isoforms differentially. Expression of the two isoforms of CD44, namely v6 and v9 seem to be related more to benign form of the tumour and could serve as a predictor of good prognosis.