[Oct4 promotes the progression and radioresistance of esophageal squamous cell carcinoma by regulating epithelial-mesenchymal transition].

<b>Objective:</b> To explore the specific role and molecular mechanism of octamer-binding transcription factor 4 (Oct4) in promoting the progression of esophageal squamous cell carcinoma and radioresistance. <b>Methods:</b> The Gene Expression Profile Data Dynamic Analysis (GEPIA) database was used to analyze the expression differences of the Oct4 gene in different types of tumor tissues and their corresponding adjacent normal tissues. The clinical data and surgical resection tissue specimens of 196 patients with esophageal squamous cell carcinoma who received surgery combined with radiotherapy at Henan Provincial Chest Hospital from January 2013 to May 2022 were collected. Immunohistochemistry was used to detect the expression of Oct4 protein in the tumor and adjacent tissues. The lentiviral packaging system was used to construct esophageal squamous cell carcinoma cell lines that up-regulated or down-regulated Oct4. The cell counting kit 8 (CCK-8) was used to detect the cell proliferation ability, the scratch test was used to detect the cell migration ability, and the clone formation test was used to detect the cell radiosensitivity. Immunofluorescence experiment was used to detect DNA damage level, and Western blot was used to detect the expressions of Oct4, human phosphorylated histone (γ-H2AX), E-cadherin, N-cadherin, vimentin, and zinc finger E box binding homology box 1 (ZEB1). <b>Results:</b> The analysis of GEPIA database showed that the expression level of Oct4 mRNA in esophageal carcinoma was higher than that in paracancerous tissues. The expression level of Oct4 protein in tumor tissues was 78.35±1.42, which was higher than that in adjacent tissues (16.27±0.49). The survival time of patients with a high expression of Oct4 was significantly shorter than that of patients with a low expression of Oct4 (25.40 and 47.00 months). Compared with the control group, the proliferation ability of KYSE510 cells in the Oct4 up-regulated group was enhanced after 72-h culture, and the cell migration ability of these cells was also enhanced, with the migration rate being (41.67±1.20)% vs (23.67±1.86)% after 24-h culture. The radiosensitivity of cells in this group decreased, with the radiosensitivity enhancement ratio being 0.69±0.06 vs 1.00±0.02. After radiotherapy, the expressions of γ-H2AX and E-cadherin decreased, while the expressions of ZEB1, vimentin and N-cadherin increased. Compared with the control group, the proliferation ability of KYSE150 cells in the Oct4 down-regulated groups 1 and 2 decreased (absorbance being 2.51±0.17, 2.38±0.16, and 3.33±0.07, respectively, <i>P</i>＜0.01) after 72-h culture, and the migration ability also decreased, with the migration rate being (13.33±0.88)%, (13.00±1.00)%, and (40.33±2.03)%, respectively (all <i>P</i>＜0.001), after 24-h culture. The radiosensitivity was enhanced, with the radiosensitivity enhancement ratio being 1.34±0.11,1.24±0.07, and 1.00±0.02, respectively (all <i>P</i>＜0.05). After radiotherapy, the expressions of γ-H2AX and E-cadherin increased, while the expressions of ZEB1, vimentin and N-cadherin decreased. Compared with the control group, the proliferation ability of KYSE510 cells in the ZEB1 down-regulated group decreased [absorbance being 1.33±0.15 vs 1.81±0.16 (<i>P</i>=0.002)] after 72-h culture. The radiosensitivity was enhanced, with the radiosensitivity enhancement ratio being 1.37±0.11 vs 1.00±0.01 (<i>P</i>=0.037), and after radiotherapy the expression of γ-H2AX increased. <b>Conclusion:</b> Oct4 is involved in the regulation of epithelial-mesenchymal transformation of esophageal squamous cell carcinoma, which promotes the proliferation, migration, and radioresistance of esophageal squamous cell carcinoma.