HCT116 cells and SW1116 cells were exponentially cultured and infected with constructed lentiviruses at a MOI of 30 for 96 h. Transfected cells were washed and re-seeded in 96-well plates at a density of 2,500 per well for HCT116 cells and 2,000 per well for SW1116 cells. Each well was treated with MTT solution dissolved in 10% SDS, 5% isopropanol and 0.01 M HCl for 10 min at 37°C, and the formazan crystals were solubilized with 100 ml of 10% SDS in 0.01 M HCl for 24 h. Cell viability was determined by measuring absorbance at a wavelength of 595 nm under a microplate reader. Cell count and optical density readings using AxioVision 4.7 microscopy software (Carl Zeiss AG, Oberkochen, Germany) were performed daily for 5 days.
Colony formation assays were performed by inoculating HCT116 and SW1116 cells into 6-well plates at the end of 96 h of lentivirus infection. In total, 500 cells per well of transfected HCT116 cells and 300 cells per well of SW1116 cells were cultured for 8 days. Colony cells were fixed with methanol and stained with 0.1% crystal violet. The number of colonies containing >50 cells was manually counted by microscopy (LSM710; Carl Zeiss AG).
Colony formation assays were performed by inoculating HCT116 and SW1116 cells into 6-well plates at the end of 96 h of lentivirus infection. In total, 500 cells per well of transfected HCT116 cells and 300 cells per well of SW1116 cells were cultured for 8 days. Colony cells were fixed with methanol and stained with 0.1% crystal violet. The number of colonies containing >50 cells was manually counted by microscopy (LSM710; Carl Zeiss AG).