Comparative Analysis of P63, Maspin and Matrix Metalloproteinase 2 Expression in Mucoepidermoid Carcinoma and Adenoid Cystic Carcinoma of Salivary Glands

STATEMENT OF THE PROBLEM: The tumor suppressor role of myoepithelial cells and related mechanisms in breast tumors are well understood. However, the role of these cells in tumors of salivary glands is debatable. PURPOSE: The present study was designed to determine the expression of p63, mammary serine protease inhibitor (maspin) and matrix metalloproteinase 2 (MMP-2) in mucoepidermoid carcinoma (MEC) and adenoid cystic carcinoma (ADCC) of salivary glands due to various cellular differentiation and structure. The association between the expression of these markers and clinicopathologic features and myoepithelial differentiation were also evaluated. MATERIALS AND METHOD: P63, maspin, and MMP-2 expression were immunohistochemically studied in 67 cases including35 cases of MEC and 32 cases of ADCC. The smooth muscle actin (SMA) staining was also applied to confirm the presence of myoepithelial differentiation. Data was analyzed using Chi-square test, Mann-Whitney U test and t-test. RESULTS: The expression of p63 (p= 0.009) and maspin (p= 0.012) significantly differed between the study groups. P63 positive cells in MEC were negative for SMA staining in contrast to ADCC. Furthermore, the expression of P63 (p= 0.045) and maspin (p= 0.019) significantly and inversely correlated with histologic grade in ADCC. Likewise, positive significant correlation was detected between histologic grade and expression of P63 (p= 0.018) and MMP-2 (p= 0.003) in MEC samples. CONCLUSION: Our findings showed that MEC is devoid of myoepithelial cells. The difference in expression of P63 and maspin in ADCC and MEC highlighted the role and presence of myoepithelial cells in ADCC. Indeed, the high expression of P63 and maspin in well-differentiated ADCCs suggests the tumor suppressor effect of myoepithelial cells. Considering the association between the evaluated markers and histological grade, p63 in both tumors, maspin in ADCC and MMP-2 in MEC may be efficient predictors of clinical behavior.