Pharmacokinetics of combined gene therapy expressing constitutive human GM-CSF and hyperthermia-regulated human IL-12

Background: an adenovirus that expresses both interleukin (il)-12 and granulocyte-macrophage colony-stimulating-factor (gm-csf) has been proven to be very effective in treating several tumors,but causes serious normal tissue toxicities. methods: in this study,a novel adenoviral vector was constructed by placing the human gm-csf gene under the control of the cmv-ie promoter and human il-12 gene under the control of heat shock protein 70b gene promoter. both hgm-csf and hil-12 expressions in virus-infected tumor cells were analyzed in vitro and in vivo when underlying single or multiple rounds of hyperthermia. results: we observed constitutive high expression of human gm-csf and heat-induced expression of human il-12 after a single round of hyperthermia post viral infection. the heat-induced hil-12 expression exhibited a pulse-like pattern with a peak at 24 hrs followed by a decline 48 hrs post heat stress. repeated heat treatment was more effective in inducing hil-12 expression than a one-time heat treatment. interestedly,we also observed that constitutive expression of hgm-csf could be stimulated by heat stress in tested tumor cells. conclusion: our study provided a novel strategy for combined gene therapy that allows constitutive expression of a non-toxic gene such as gm-csf and heat-induced expression of a toxic gene such as il-12. in addition,our study also showed that hyperthermia can be used to trigger gene expression in temporal and special manner. © 2013 wei et al.