In vitro study of the effect of small interfering ribonucleic acid on the expression of FOXN1 and B cell-attracting chemokine 1 in thymoma cell lines

BACKGROUND To determine the relationship between FOXN1 (a transcription factor) and B cell-attracting chemokine 1 (BCA1, a chemotactic factor), and their influence on thymoma cell proliferation. METHODS We initially used immunohistochemical methods to compare the expression levels of FOXN1 and BCA1 in thymoma and non-thymomatous tissue samples. Reverse transcription polymerase chain reaction (RT-PCR) and Western blotting were used to compare the expression of FOXN1 and BCA1 in thymoma cells (Thy0517) and normal thymic epithelial cells (CRL7660). We used ribonucleic acid interference (RNAi) to downregulate FOXN1 and BCA1 expression in Thy0517 cells to determine the relationship of the two factors with cell regulation. We also performed methyl thiazolyl tetrazolium (MTT) [3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide] assays to detect the changes in Thy0517 cells after RNAi of FOXN1 and BCA1. RESULTS FOXN1 and BCA1 expression levels were higher in thymoma tissues and Thy0517 cells compared to non-thymomatous tissue and CRL7660 cells (P < 0.05). RT-PCR and Western blot following RNAi showed that FOXN1 controlled BCA1 expression. MTT assay showed that FOXN1 and BCA1 downregulation rapidly inhibited Thy0517 cell proliferation. CONCLUSIONS FOXN1 and BCA1 expression was higher in thymoma tissue samples and cell lines than in non-thymomatous tissue and normal thymic epithelial cells. FOXN1 acts upstream of BCA1 and both FOXN1 and BCA1 promote thymoma cell proliferation.