ZEB1 expression in different stages of colorectal cancer.

e15526 Background: Colorectal cancer (CRC) is among the most common cancers. The leading cause of high mortality is tumor progression developed due to the epithelial to mesenchymal transition (EMT). The ZEB1 protein is one of the critical regulators of this process. In this regard, our study aimed to assess the ZEB1 expression in different stages of colorectal cancer. Methods: This study included samples of 206 patients with stage II-IV CRC aged 42 to 86 years (mean age 64.2±1.7). All patients were divided into three groups: group 1 - patients with T3-4 N0 M0 (stage II) with high-risk factors for recurrence, n = 6; group 2 - patients with T1-4 N1-2 M0 (stage III), n = 88; group 3 - patients with T1-4 N0-2 M1 (stage IV), n = 58. IHC study was performed using polyclonal rabbit antibodies to ZEB1 (Biorbyt Ltd.) diluted 1:200 and a Reveal Polyvalent HRP-DAB Detection System. The staining percentage and intensity were assessed: 0, 1+ weak, 2+ moderate, 3+ strong. The nuclear reaction of the ZEB1 protein was considered positive when staining was detected in more than 10% (cut-off) of tumor cells with intensities of 2+ and 3+. Statistical analysis of the results was carried out using the STATISTICA 13.0 software (StatSoft Inc., USA). Results: A positive nuclear reaction for ZEB1 was detected in 80.6% (166 of 206 patients), while negative in 19.4% (40 of 206 patients). The maximal percentage of patients with positive staining for ZEB1 was among those with stage IV (94.8%), the minimal percentage - stage II (60%). The prevalence of ZEB1+ in patients with stages III and IV significantly increased the risk of tumor progression by 3.5 (95% CI 1.8-8.4) and 12.2 (95% CI 3.4-43.6) times, respectively, compared with stage II patients. No statistical significance was observed in the comparison between patients with stages III and IV (95% CI 0.9-11.7). The percentage of ZEB1+ samples increased in more advanced tumors. The ratio of ZEB1+/ZEB1- tumors in stage II was 1.5, in stage III - 5.8, in stage IV - 18.3 (p < 0.05). Conclusions: The immunohistochemical study revealed the features of ZEB1 expression in different stages of colorectal cancer, which can serve as prognostic factors that determine the disease progression.