Enhancing the radiosensitivity of colorectal cancer cells by reducing spermine synthase through promoting autophagy and DNA damage

Figure 2 Down-regulation of spermine synthase enhances the radiosensitivity of HCT116 cells, inhibits cell proliferation, and promotes apoptosis. A: MTT assay to detect the viability of HCT116 cells in the negative control shRNA (shNC) group, shNC + IR group, spermine synthase shRNA (sh-SMS) group, and sh-SMS + IR group; B: Colony formation assay to assess the colony formation ability of HCT116 cells in the shNC group, shNC + IR group, sh-SMS group, and sh-SMS + IR group; C: Flow cytometry analysis to measure the apoptosis levels of HCT116 cells in the shNC group, shNC + IR group, sh-SMS group, and sh-SMS + IR group. ^bP < 0,01 vs shNC, ^dP < 0.01 vs shNC + IR, ^fP < 0.01 vs sh-SMS; SMS: Spermine synthase; sh-SMS: Spermine synthase shRNA; shNC: Negative control shRNA; OE-SMS: Spermine synthase over-expression vector; OE-NC: Negative control over-expression vector.