Comparative Growth Kinetics of HPV-Positive and HPV-Negative Cell Lines

SiHa [HPV16(+)] and HeLa [HPV18(+)] cells were obtained from ATCC (#HTB-35 and #CCL-2, respectively) (Manassas, USA). HaCaT [HPV(−)] cells were kindly provided by F. De Marco (Regina Elena Institute for Cancer Research, Rome, Italy). Cell cultures were maintained in Dulbecco's modified Eagle's medium supplemented with 10% fetal calf serum. Selection of HeLa_CDV and HaCaT_CDV cells was performed as previously described for SiHa_CDV cells [48 (link)]. The growth rate of CDV^R cells compared to parental cells was evaluated as previously reported [48 (link)]. Doubling time (DT) was calculated with the formula: DT = (t₂–t₁)/(log₂N₂-log₂N₁), where t₁ and t₂ are the times at which the cells were counted, and N₁ and N₂ are the cells numbers at times t₁ and t₂.