Abstract
BackgroundGene therapy is a promising therapeutic approach for cancer. Targeted expression of desired therapeutic proteins within the tumor is the best approach to reduce toxicity and improve survival. This study is to establish a more effective and less toxic gene therapy of cancer.MethodsCombined gene therapy strategy with recombinant adenovirus expressing horseradish peroxidase (HRP) mediated by human telomerase reverse transcriptase (hTERT) promoter (AdhTERTHRP) and murine interleukin-12 (mIL-12) under the control of Cytomegalovirus (CMV) promoter (AdCMVmIL-12) was developed and evaluated against Lewis lung carcinoma (LLC) both in vivo and in vitro. The mechanism of action and systemic toxicities were also investigated.ResultsThe combination of AdhTERTHRP/indole-3-acetic acid (IAA) treatment and AdCMVmIL-12 resulted in significant tumor growth inhibition and survival improvement compared with AdhTERTHRP/IAA alone (tumor volume, 427.4 ± 48.7 mm3 vs 581.9 ± 46.9 mm3, p = 0.005 on day 15; median overall survival (OS), 51 d vs 33 d) or AdCMVmIL-12 alone (tumor volume, 362.2 ± 33.8 mm3 vs 494.4 ± 70.2 mm3, p = 0.046 on day 12; median OS, 51 d vs 36 d). The combination treatment stimulated more CD4+ and CD8+ T lymphocyte infiltration in tumors, compared with either AdCMVmIL-12 alone (1.3-fold increase for CD4+ T cells and 1.2-fold increase for CD8+ T cells, P < 0.01) or AdhTERTHRP alone (2.1-fold increase for CD4+ T cells and 2.2-fold increase for CD8+ T cells, P < 0.01). The apoptotic cells in combination group were significantly increased in comparison with AdCMVmIL-12 alone group (2.8-fold increase, P < 0.01) or AdhTERTHRP alone group (1.6-fold increase, P < 0.01). No significant systematic toxicities were observed.ConclusionsCombination gene therapy with AdhTERTHRP/IAA and AdCMVmIL-12 could significantly inhibit tumor growth and improve host survival in LLC model, without significant systemic adverse effects.
Highlights
Gene therapy is a promising therapeutic approach for cancer
horseradish peroxidase (HRP) and IL-12 expression in vitro Lewis lung carcinoma (LLC) cells transduced with AdCMV(-), AdhTERTHRP and AdCMVmIL-12 alone or in combination were harvested and determined by western blot for the expression of HRP
Results showed that the HRP expression was observed in AdhTERTHRP alone group and combination group whereas not in AdCMV(-) or AdCMVmIL-12 alone groups (Figure 2B)
Summary
Gene therapy is a promising therapeutic approach for cancer. Targeted expression of desired therapeutic proteins within the tumor is the best approach to reduce toxicity and improve survival. Gu et al[9] showed that hTERT promoter could efficiently use mouse transcription machinery despite the apparent distinct regulatory mechanisms, and that hTERT promoter was highly active in murine tumor cells, but quiescent in normal murine cells and tissues. These findings indicated that hTERT promoter should be useful for targeting the pharmaceutical effects of a therapeutic gene to cancer cells
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