Research On The Biological Characteristics Of Tumor Associated Fibroblasts Derived From Salivary Pleomorphic Adenomas

Objective: Pleomorphic adenoma (PA) is the most common benign tumor in theoral and maxillofacial regions.PA accounted for51%of epithelial tumors of the salivarygland and88%of the benign tumors. The numbers of Women are more than men.PAcan occur at any age especially30-60years old. The most common sites are parotid andsubmandibular glands. About80%-90%PA are in the parotid gland withapproximately3%-4%metastasis and death. Although PA is a benign tumor, itscapsule is often invaded by tumor cells. The biological behaviors of PA are betweenbenign and malignant tumors. According to its biological characteristic, PA can also beclassified as a critical tumor. PA tends to recur after surgery，and can affect theappearance with expansive growth of the tumor. The recurrence rate after Five years isabout3.4%. Repeatedly relapse can lead to malignant change. The more relapses thehigher possibility of malignant transformation. The purpose of the study is to investigatewhether tumor-associated fibroblasts (TAFs) exist in PA. If TAFs do exist in PA, theirbiological features will be further studied and compared with TAFs from salivaryadenoid cystic carcinoma (ACC).Materials and Methods: Our study includes66cases of PA and18cases ofnormal salivary glands as control. Immunohistochemical staining was performed todetect Vimentin (VIM), a-smooth muscle actin (a-SMA) and matrix metalloproteinaseprotease2(MMP-2) protein expression in tissues. The protein expression level wasanalyzed by Image pro-plus6.0(IPP6.0). Statistical analysis (p <0.05for significantdifference) was performed by SPSS16.0software. TAFs were isolated from PA andACC tumor tissues. Their migration abilities were compared.Results: No significant difference of VIM expression in PA and controls was found (p>0.05). Expression of α-SMA in PA stroma is significantly higher than that inthe controls (p <0.001). TAFs from PA migrated slower than that from ACC.Expression of MMP-2in the PA stroma are significantly higher than that in the controls(p <0.001), but significantly decreased compared to the stroma of ACC (p <0.05).Conclusion: TAFs exist in the PA. TAFs from PA showed lower migration abilitythan that from ACC. MMP-2expression increased in TAFs from PA, compared to thatfrom normal controls. But MMP2expression decreased in PA stroma, compared toACC stroma.