Biomarkers of epithelial-mesenchymal transition in localized, surgically treated clear-cell renal cell carcinoma.

INTRODUCTION: It has been suggested that the metastatic potential of neoplastic cells can be predicted on the basis of their biological features, including expression of proteins involved in the epithelial to mesenchymal transition (EMT). Therefore, the purpose of this work was to (1) evaluate the expression of EMT markers: ZEB2, vimentin, N-cadherin, TWIST, PTEN, survivin, E-cadherin, Ki-67 and GLUT-1, (2) assess mutation status of two genes: PIK3CA and KRAS, and (3) investigate the potential relationships between the studied biomarkers and clinicopathological factors in clear-cell renal cell carcinoma (ccRCC).

MATERIAL AND METHODS: . Tumor tissue samples (embedded in paraffin blocks) from 159 patients undergoing radical nephrectomy were analyzed. Proteins expression was evaluated immunohistochemically. DNA mutations were analyzed on DNA isolated from tumor tissue and amplified by real-time PCR detection using suitable fluorescent labeled TaqMan assays.

RESULTS: . One hundred and seven men and 52 women of mean age of 63.1years were enrolled. Fifty four cancers at pTNM stage I-II and 98 at pTNM III-IV stage were diagnosed. There were 30 Fuhrman grade G1, 61 Fuhrman G2, 49 Fuhrman G3 and 19 Fuhrman G4 tumors. A negative correlation between ZEB2 (p = 0.047, r = -0.172) or E-cadherin expression (p = 0.027, r = -0.191) and TNM was observed. Positive association between grade and Ki-67 (p < 0.001), survivin (p < 0.001), vimentin (p < 0.001) immunoreactivity and negative association between TWIST expression (p = 0.029) or PTEN expression (p = 0.013) were found. Ki67 expression was positively correlated with survivin (p < 0.001, r = 0.617), vimentin (p = 0.001, r = 0.251) and N-cadherin (p = 0,009, r = 0.207) immunoreactivity which can suggest tumor aggressiveness. TWIST was negatively correlated with E-cadherin (p < 0.001, r = -0.284), vimentin (p < 0.001, r = -0.297) and N-cadherin (p < 0.002, r = -0.241). ZEB2 was not associated with ccRCC grade but was negatively correlated with E-cadherin (p = 0.055, r= -0.153) and PTEN (p = 0.006). GLUT-1 expression was inversely linked to E-cadherin expression (p = 0.022, r= -0.182). Mutations in PIK3CA and KRAS genes were not found in any of the studied ccRCC tumors.

CONCLUSIONS: . Low-grade tumors showed higher expression of ZEB2 and TWIST proteins than high-grade tumors, which can suggest that EMT in ccRCC begins at early stages of tumor development and, therefore, evaluation of these proteins, together with other biomarkers, may be useful for assessment of the tumor metastatic potential.