Figure 4. Trachinus vipera venom induces accumulation in G₁ phase of cell cycle and stops DNA synthesis.

(A,B) Cell cycle analysis. Human colon carcinoma HCT116 cells were exposed to 500 μg/ml Trachinus vipera venom for 72 h followed by the cytofluorometric assessment of cell cycle distribution. (A,B) report representative cell cycle distributions and quantitative data (mean ± SEM; n = 3). (C,D) G₁ phase staining. HCT116 cells were cultured in the presence of venom for 72 h, fixed and then labeled with an antibody recognizing cyclin E, which accumulates essentially in the G₁ phase. Cells were acquired using cytofluorometry. Representative scatter plots (C) and quantitative results (D) (mean ± SEM; n = 3) are shown. (E,F) DNA synthesis evaluation. HCT116 cells were cultured in the presence of 500 μg/ml Trachinus vipera venom and after 72 h labeled with the thymidine analog EdU, which selectively stains cells in the S phase of the cell cycle. Cell were fixed and acquired by cytofluorometry to evaluate the level of EdU incorporation. Representative scatter plots (E) and quantitative results (F) (mean ± SEM; n = 3) are shown. Numbers indicate the percentage of cells found in each quadrant. *p < 0.05 (Student’s t-test), as compared with non-treated cells.