Local tumor irradiation augments the antitumor effect of cytokine-producing autologous cancer cell vaccines in a murine glioma model

Abstract

The combined therapeutic effect of cytokine-producing cancer cell vaccines and local radiotherapy was studied in a mouse glioma 261 (Gl261) brain tumor model. Brain tumor-bearing mice were treated with cytokine (IL-4, IL-6, IL-7, GM-CSF, TNF-, LIF, LT) producing vaccines made by in vitro transduction of Gl261 cells with the corresponding adenoviral vectors. Vaccines producing either IL-4 or GM-CSF cured 20-40% of mice. The antitumor effect strongly depended on the secreted cytokine level. Vaccination therapy induced specific activation of cytotoxic T lymphocytes measured by cell-mediated cytotoxicity assay. Brain tumors were heavily infiltrated by CD4 + lymphocytes after treatment with IL-4-or GM-CSF-secreting cells. GM-CSF vaccination induced moderate CD8 + infiltration, as well. Depleting either CD4 + or CD8 + lymphocyte subsets abolished the anticancer effect of GM-CSF-expressing cells. Strong synergism was observed by combining cytokine vaccination (GM-CSF, IL-4, IL-12) with local tumor irradiation: about 80-100% of the glioma-bearing mice was cured. The high efficiency of combined treatment was maintained even under suboptimal conditions when neither of the modalities cured any of the mice alone. This suggests that vaccination therapy might open a new potential in the clinical treatment of high-grade gliomas when applied as adjuvant to existing treatment modalities.

Activation of a glioma-specific immune response by oncolytic parvovirus Minute Virus of Mice infection

“…Indeed, in a therapeutic vaccination approach against intracranial GL261-derived tumors, depletion of either CD4 þ or CD8 þ T lymphocytes proved to impair the antitumor effect of the vaccine. 24 In conclusion, the present study shows that the interaction of PVs with cancer cells can lead not only to direct oncolysis, but also to a break of the immune tolerance to tumors, resulting in synergistic effects of virus infection and host immune reactions on tumor suppression. In at least some tumor models, as the one studied in this work, immune cells appear to be the main effectors of PV-dependent tumor destruction.…”

Synergism between GM–CSF and IFNγ: Enhanced immunotherapy in mice with glioma

“…The GL261 cell line was induced by intracerebral implantation of methylcholanthrene (MCA) pellets and later established as a permanent cell line. 20 The pMG plasmid (Invivogen, San Diego, CA) containing the gene for murine GM-CSF was used for transducing the GL261 cell line (GL-GM). Cytokine production was measured in supernatants from 1 3 10 5 GL-GM cells cultured for 48 hr with a mouse GM-CSF ELISA kit (Pharmingen, San Diego, CA).…”

Adenoviral vector transduction of the human deoxycytidine kinase gene enhances the cytotoxic and radiosensitizing effect of gemcitabine on experimental gliomas

“…The Gl261 cell line was established in our lab from the in vivo growing Gl261 tumor. [12][13][14] All cell lines were cultured in Dulbecco's Modified Eagle's Medium (DMEM) supplemented with 10% fetal calf serum and appropriate antibiotics.…”

“…13 To determine transduction efficiency, Gl261, U373 and C6 cells were infected with an adenoviral vector (AdexCAlacZ) encoding the bacterial b-galactosidase (lacZ) gene at different multiplicities of infection (MOI) and lacZ activity measured as described. 13 In vitro sensitivity of glioma cell lines to dCK overexpression, gemcitabine treatment and irradiation To determine the sensitivity of the Gl261, C6 and U373 cell lines to gemcitabine, cells were seeded in 25 cm 2 tissue culture dishes at day 1 using the following cell densities: 20 Â 10 3 , 12 Â 10 3 and 6 Â 10 3 cells cm À2 for Gl261, U373 and C6 cells, respectively. The next day, cells were treated with increasing concentrations of gemcitabine.…”