Cellular DNA replication machinery

The cellular DNA replication machinery, primarily consisting of DNA polymerases, serves as the functional target in the Herpes Simplex Virus Thymidine Kinase (HSV-TK) suicide gene therapy system (Source: PubMed ID 12812486). In this therapeutic strategy, tumor cells are engineered to express the viral HSV-TK gene, which can phosphorylate specific nucleoside analogs like ganciclovir (GCV) that human thymidine kinases cannot efficiently process (Source: StatPearls, Ganciclovir). Once converted to GCV-monophosphate by the viral enzyme, cellular kinases further phosphorylate it into GCV-triphosphate, a potent deoxyguanosine triphosphate (dGTP) analog (Source: PubChem, Ganciclovir). During the S-phase of the cell cycle, the cellular DNA replication machinery incorporates GCV-triphosphate into the growing DNA strand, leading to immediate chain termination or the accumulation of lethal DNA damage (Source: PubMed ID 10653434). This process triggers apoptosis specifically in dividing cells, providing a mechanism to selectively eliminate tumor populations while sparing quiescent normal cells. Additionally, the system benefits from the bystander effect, where the toxic metabolites are transferred to adjacent cells through gap junctions, extending the therapeutic impact beyond the initially transduced cells (Source: PubMed ID 15542144).

Other names

DNA synthesis machineryDNA polymerase complexReplisomeDNA replication apparatus

The active metabolite ganciclovir-triphosphate (GCV-TP), produced only in cells expressing HSV-TK, acts as a deoxyguanosine triphosphate (dGTP) analog that is incorporated into DNA by cellular DNA polymerases, leading to DNA chain termination and apoptosis (Source: PubMed ID 12812486).