Down-regulated expression of family with sequence similarity 3, member B (FAM3B), in oral squamous cell carcinoma

PurposeFamily with sequence similarity 3, member B (FAM3B), also known as PANcreatic DERived factor (PANDER), is an islet-specific cytokine predominantly expressed in both pancreatic α- and β-cells. FAM3B is known to induce apoptosis in pancreatic cells, and may therefore be able to regulate apoptosis in other cell types, including cancer cells. However, the role of FAM3B in carcinogenesis is unknown. We previously performed global gene screening using DNA microarray analysis to identify crucial molecules in oral squamous cell carcinoma (OSCC). The results showed significant down-regulation of FAM3B in OSCC-derived cell lines, as compared with human normal oral keratinocytes (HNOKs). The aim of the present study was to clarify the association between FAM3B and OSCCs.ResultsExpression profiles of FAM3B in OSCC-derived cell lines and human primary OSCCs were examined by real-time quantitative reverse transcriptase-polymerase chain reaction and Western blot analysis. Significantly decreased expression of FAM3B mRNA and FAM3B protein were observed in five OSCC-derived cell lines, as compared with HNOKs. Moreover, immunohistochemical analysis revealed down-regulated FAM3B protein expression in primary OSCC samples. In order to examine whether microRNA (miRNA) potentially regulates FAM3B expression, miRNA microarray analysis was performed with OSCC-derived cell lines. miRNA microarray data showed that miR-181a, miR-181b, miR-200b, and miR-200c, which can induce imperfect base pairing with the 3′-untranslated region of FAM3B mRNA, were up-regulated in all cell lines examined.ConclusionsThese results indicate that decreased FAM3B expression is able to promote OSCC progression and that certain miRNAs may be correlated with the altered expression of FAM3B.

▸ Decreased expression of FAM3B was observed in OSCC-derived cells and OSCC samples. ▸ There was a significant relationship between FAM3B expression and primary tumor size. ▸ FAM3B may be a useful biomarker of progression in primary OSCC.