[Different susceptibility of cell lines to thymidine kinase/ganciclovir-mediated killing effect and the way of cell death].
OBJECTIVE
To investigate the mechanism of variability of herpes simplex virus (HSV) thymidine kinase (TK)/ganciclovir (GCV)-mediated suicide effect obtained in three different cell lines and the ways in which this system-mediated cell killing occurs.


METHODS
Recombinant retroviral vector expressing HSV-TK was transduced into three cell lines known with different growth rate (PC-2, PC-7 and LLC-PK1). The doubling time of the transduced and parental cells was calculated. MTT method was used to detect the concentration of GCV at which cell growth was inhibited by 50% (IC(50) value). Cell cycle was analyzed by flow cytometry. Necrosis or apoptosis of cultured cells and/or xenografts was observed under light and electron microscope, and by in situ apoptosis detection.


RESULTS
The doubling time of the three parental cell lines was (31.2 +/- 0.1) h, (48.3 +/- 0.1) h, and (53.9 +/- 0.1) h, separately. The IC(50) values of their HSV-TK-transduced cell lines to GCV were (0.73 +/- 0.12) micromol/L, (0.93 +/- 0.16) micromol/L and (1.22 +/- 0.06) micromol/L, respectively and the IC(50) value was correlated with the cell doubling time. Flow cytometry revealed S arrest. The majority of cells under treatment of GCV displayed swelling and collapse, but very few cells showed apoptosis. Large areas of necrosis were observed in the xenografts.


CONCLUSIONS
The cells with high growth rate are more susceptible to HSV-TK/GCV-mediated killing effect. Necrosis is the main way in which cells of the three HSV-TK-transduced cells lines die.
Zhang
L
L
Department of Pathology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100730, China.
Liu
T
T
Cui
Q
Q
Gao
J
J
D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D005260:Female; D015774:Ganciclovir / Q000494:pharmacology*; D041722:Genes, Transgenic, Suicide; D006801:Humans; D018374:LLC-PK1 Cells; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009336:Necrosis; D009368:Neoplasm Transplantation; D010190:Pancreatic Neoplasms / Q000473:pathology*; D012190:Retroviridae / Q000235:genetics; D018139:Simplexvirus / Q000201:enzymology* / Q000235:genetics; D013552:Swine; D013937:Thymidine Kinase / Q000235:genetics*; D014161:Transduction, Genetic
D000998:Antiviral Agents; D013937:Thymidine Kinase; D015774:Ganciclovir