Research On The Biological Features Of Tumor Associated Fibroblasts Derived From Salivary Adenoid Cystic Carcinoma

Objectives: Salivary gland adenoid cystic carcinoma (ACC) is one of the mostcommon malignant tumors in the oral and maxillofacial region. It accounts for27%ofepithelial salivary gland malignancies. The purpose of this study is to investigate iftumor associated fibroblasts (TAFs) exist in ACC tissues. If TAFs do exist in ACC,their biological features will be further examined.Methods: Immunohistochemistry was used to detect the expressions of Vimentin(VIM), α-Smooth muscle actin (α-SMA) and Matrix metalloproteinase2(MMP2) in18cases of ACC and18cases of normal salivary glands. ImagePro Plus6.0softwarewas used to quantify the expression level of each antibody. SPSS17.0was used forstatistical analysis. Primary TAFs were isolated from a fresh human ACC tumorsurgical specimen and their identity was confirmed by immunofluorescence staining.Total RNA isolated from primary TAFs was transcripted to the first-strand cDNA bythe Reverse transcription polymerase chain reaction (RT-PCR). PCR amplification wasused to detect the expressions of matrix metalloproteinases.Results: VIM expression was positive in the stroma of normal salivary glands andACC. Statistical analysis showed no significant difference between them. α-SMAshowed negative expression in the stromal fibroblasts in normal salivary glands butpositive expression in the stromal fibroblasts of ACC. A significant difference wasfound between them. Primary TAFs were isolated from one case ACC. These cellsshowed higher expression of MMP2than HFL1, a normal fibroblast cell line.Immunohistochemical staining also proved higher MMP2expression in the stroma ofACC than that in the normal salivary glands (p <0.001).Conclusions: This study proved that TAFs exist in ACC. TAFs derived fromACC showed high level expression of MMP2. Our results suggest that TAFs mightpromote ACC invasion by secreting MMP2.