Mammaglobin protein localization and gene expression in the salivary glands

Purpose: This study aims to delve deeper into the hypothesis that normal salivary gland tissue expresses both protein and mRNA of mammaglobin (MGB). Methods: Formalin-fixed paraffin-embedded samples of submandibular (10), parotid (5), palatal (5) and labial glands (30) salivary glands were immunohistochemically investigated. The labial samples were used to examine the MGB positive ratio (MGB-PR), and localize MGB by double immunofluorescence staining and quantitative mRNA gene expression. Mann-Whitney U and Kruskal Wallis rank-sum test for group comparison, and Spearman's rank correlation coefficient for correlation analysis were used. Results: The distribution of MGB-positive cells was variable through-out samples with significantly higher MGB-PR of acini than ducts (P = 0.00376), and there was no difference when compared based on age (P = 0.0646) and gender (P = 0.245). Besides acinar cells, a number of myo-epithelial cells and ductal cells also demonstrated strong MGB reactivity with varying MGB mRNA expression levels in 6 of the 7 samples (with MGB-PR > 20%) tested. Conclusion: This novel study shows that unlike aberrant protein expres-sion in some carcinomas, MGB expression in salivary gland neoplasms represents the nature of original cells, giving a better insight into the neo-plasms expressing MGB.

Automated summary

This study delved into the hypothesis that normal salivary gland tissue expresses both protein and mRNA of mammaglobin (MGB). The results showed that MGB-positive cells were distributed variably, with higher MGB-PR in acinar cells than ductal cells. Additionally, MGB expression in salivary gland neoplasms represents the nature of original cells.