Oral 2.04: Expression and significance of c-kit and EMT molecules in thymic epithelial tumors

Background: To investigate the expression and significance of c-kit and EMT molecules (E-cadherin, N-cadherin, Twist, Snail) in thymic epithelial tumors.

Methods: By using the tissue microarray technology and immunohistochemistry MaxVision^TM-use kit to detect the expression of c-kit and EMT molecular markers (E-cadherin, N-cadherin, Snail, Twist) in 150 cases of paraffin sections of thymic epithelial tumor tissue, analysis the correlation between c-kit and EMT molecules; explore the malignancy degree and clinicopathological parameters relationship between c-kit, EMT molecules and thymic epithelial tumors.

Results: The difference of c-kit positive expression in thymoma between the subtypes (A 9.09%, AB 2.86%, B1 5.26%, B2 5.00%, B3 8.70%) was no statistically significant (P>0.05); while the positive expression rate of thymic carcinoma 68.18% (15/22) was significantly higher than thymoma 5.47% (7/128), the difference between them was statistically significant (P<0.01). The difference of E-cad positive expression in thymoma between the subtypes (A 81.82%, AB 85.71%, B1 78.95%, B2 80.00%, B3 73.91%) was no statistically significant (P>0.05); the positive expression rate of thymoma 80.47% (103/128) was significantly higher than thymic carcinoma 22.73% (5/22), the difference between them was statistically significant (P<0.01). The difference of N-cad positive expression in thymoma between the subtypes (A 0%, AB 0%, B1 5.26%, B2 5.00%, B3 8.70%) was no statistically significant (P>0.05); the positive expression rate of thymic carcinoma 63.64% (14/22) was significantly higher than thymoma 3.91% (5/128), the difference between them was statistically significant (P<0.01). The difference of Twist positive expression in thymoma between the subtypes (A 18.18%, AB 14.29%, B1 21.05%, B2 20.00%, B3 21.74%) was no statistically significant (P>0.05); the positive expression rate of thymic carcinoma 72.73% (16/22) was significantly higher than thymoma 18.75% (24/128), the difference between them was statistically significant (P<0.01). The difference of Snail positive expression in thymoma between the subtypes (A 9.09%, AB 8.57%, B1 15.79%, B2 12.50%, B3 21.74%) was no statistically significant (P>0.05); the positive expression rate of thymic carcinoma 77.27% (17/22) was significantly higher than thymoma 13.28% (17/128), the difference between them was statistically significant (P<0.01). c-kit expression and E-cad expression was negatively correlated; c-kit expression and N-cad, Twist, Snail was positively correlation. E-cad expression and N-cad, Twist, Snail was negatively correlation. N-cad expression was positively correlated with Twist, Snail. Twist and Snail expression was positively correlated.

Conclusions: (I) The expression of c-kit, E-cadherin, N-cadherin, Twist and Snail in each tissue subtype of thymoma were no significantly differences; while their expression between thymic carcinoma and thymoma were statistically significant, suggesting that these five indicators may help to determine the malignant degree of thymic epithelial tumors; (II) the expression of c-kit and E-cad was negatively correlated while the expression of c-kit with N-cad, Twist and Snail was positively correlated, suggesting that overexpression of c-kit may promote the EMT process of thymic epithelial tumors; (III) the expression of Twist and Snail was positively correlated, suggesting that Twist and Snail may have a synergistic effect, both of them combined expression can better promote tumor metastasis.

Keywords: Thymic epithelial tumors; c-kit; EMT; Snail; Twist