Background: Salivary gland neoplasms are originated from the various salivary gland compartments and are histologically related to these structures. Several protein and molecular markers are employed in research and diagnosis in order to classify and understand histogenesis and other aspects of salivary gland neoplastic lesions. Pleomorphic adenoma is a benign salivary gland neoplasm composed by epithelial and myoepithelial cells and a complex stroma. Its varied structural and architectural aspects suggest the participation of stem cells in its composition. Additionally, pleomorphic adenoma originates from intercalated duct of salivary glands, a region reputed to host the regenerative/ stem-cell compartment of these glands. The present work investigated stem-cell markers (CD24, CD44) in pleomorphic adenoma and in specimens of developing human salivary glands using immunohistochemistry and real-time RT-PCR. Material and Methods: 101 cases of pleomorphic adenomas were used - 55 cases were FFPE and 60 specimens were fresh frozen tissue. From the total, 14 were pared (FFPE and frozen tissue). Salivary gland specimens dissected from 20 human foetuses were also included. Results: All cases of pleomorphic adenomas were positive for the stem-cell markers studied. Neoplastic luminal structures were positive for CD24. Modified myoepithelial cells were positive for CD44. In foetal salivary glands, these markers were restricted to the intercalated duct region. Increased expression of CD44 stem-cell marker was observed in pleomorphic adenoma specimens using real-time RT-PCR technique when compared to normal salivary gland controls. An specific expression pattern was not observed for CD24 when compared to the normal salivary gland tissue - in some cases of pleomorphic adenoma there was an increased expression of the protein, whilst in other cases the expression was decreased or normal-like. Conclusion: Pleomorphic adenoma cells share similar markers with stem-cells; it is not possible to confirm that neoplastic cells bear the same characteristics of multipotency.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5352. doi:1538-7445.AM2012-5352