In this study, we first constructed a novel adenoviral vector that allowed constitutive expression of human GM-CSF and heat-induced expression of human IL-12. The pharmacokinetics of gene expression Selleck GS-9973 triggered by hyperthermia was then tested in cell culture and in an animal model.
Our study provided insights on tumor therapy by combining gene therapy with hyperthermia. Materials and methods Cell culture A549, a human non-small cell lung carcinoma cell line, and Hep3B, a human hepatoma cell line, were purchased from American Type Culture Collection. All cells were cultured in RPMI 1640 with 10% fetal bovine serum, 100 units/mL penicillin, and 100 μg/mL streptomycin at 37°C, 5% CO2. Adenovirus preparation The adenovirus used to establish constitutively high expression of human
GM-CSF and heat-inducible expression of human IL-12 was constructed according to established protocols  using commercially available plasmids (Microbix, Toronto, Canada). To construct the heat-inducible IL-12 expression cassette, cDNAs for both the p40 and p35 subunits of human IL-12 were inserted into the E1 region under control of the human hsp70B gene promoter [13, 14]. The p40 and p35 subunits were connected using an internal ribosome entry site sequence  so that both subunits could be transcribed under the control of the same promoter. The human GM-CSF expression cassette was constructed by placing the human GM-CSF gene under the control of a constitutively GF120918 active CMV-IE promoter in the E1 region  (see Figure 1). The completed adenovirus called Adcmv-GMCSF-HSP-IL12 will establish constitutive expression of human GM-CSF and heat-inducible expression of human IL-12. Large scale preparation of recombinant Adcmv-GMCSF-HSP-IL12 was accomplished as previously described . The control vector is an adenovirus expressing GFP protein (Figure 1). Figure 1 A schematic diagram of adenovirus
used in this study. HSP70-pro: heat shock protein 70 gene promoter; hIL12: human interleukin 12; CMV-pro: CMV promoter; hGMCSF: granulocyte-macrophage colony-stimulating-factor gene; EGFP: enhanced GFP. In vitro heating experiments A549 and Hep3B cells were seeded in 24-well plates at a density of 6 × 104 cells/well. After cells were cultured for 24 hrs, 100, 500, and 1000vp (viral many particles) of Adcmv-hGMCSF-hsp-hIL12 virus were added into each well. see more Twenty-four hours later, the culture medium was replaced with 1 ml of fresh medium containing 2% FCS and cells were heated in a 45°C water bath for 45 min. Twenty-four hours later, the medium was collected for hGM-CSF and hIL-12 measurement and replaced with 1 ml of fresh medium. Cells were heated again (45°C, 45 min) and the medium was collected 24 hrs post heating. In vivo heating experiments Balb/C nude mice (BALB/c, nu/nu) weighing 20-22 g were provided by the animal center of Shanghai Biological Science Institution and housed in rooms under standard lighting conditions and temperature.