Killing effects of ganciclovir on human pulmonary adenocarcinoma cell A549transduced with HSV1-TK gene in vitro and in vivo

Aim: To observe the killing effects of ganciclovir (GCV) on the human pulmo nary adenocarcinoma cell A549 transduced with Herpes simplex virus I type t hymine kinase (HSV1-TK) gene in vitro and in vivo. Methods: A retroviral ve ctor containing the TK gene was constructed and transduced into a pulmonary carcinoma cell A549 by electroporation, to observe the sensitivity of the transfected cell to GCV in vitro and the bystander effect (NM assay). Tumor cell apoptosis caused by the TK/GCV system was observed with a flow cell m eter (FCM) and a scan electronic microscope (SEM). Recombination and expres sion of the TK gene were examined with DNA PCR and in situ hybridization, r espectively. The therapeutic effect of GCV on subcutaneous tumor growth bet ween transfected and parental cells was also compared. Results: The sensiti vity of the transfected cell to GCV was 46 times higher than that of the pa rental cell, and the bystander effect was stronger in high cell density tha n in low cell density. The subG(0)G(1) peak was shown on the DNA histogram after A549-Tk cell was treated with 50 mu mol/L GCV for 3 days by FCM, but not in the A549 cell. A cell cycle analysis showed that the apoptotic cell in the A549-TK and A549 cells were (12.2 +/-1.7) % and (1.3 +/-0.3) %, resp ectively (P<0.01). The cell apoptosis features of nuclear condensation, apo ptotic vesicle, and nuclear showing semimoon feature were found in the A549 -TK cell by SEM, but not in the A549 cell. Recombination and expression of the TK gene were positive in the transfected cell. In vivo, the growth of t umors formed by the transfected cell was apparently inhibited by GCV, but n ot in the control group. Conclusion: The transfected cell obtained sensitiv ity to GCV and the bystander effect was closely related to intercellular to uch. The TK/GCV system killing tumor cell was related to cell apoptosis. GC V inhibited the growth of tumors which were inoculated by A549-TK cell in v ivo.