Abstract
AbstractMicroglia has been found to diversify its function by cancerous cells or in a cancerous environment, thereby contributing to cancer growth and metastasis. Its immuno-activity, however, can be modulated by interleukin-12. So a strategy was designed using AAV2 carrying IL-12 to activate microglia then to eliminate cancerous cells. The transduction efficacy of AAV was evaluated with AAV2 encoding GFP and IL-12 on cancerous and CNS cells. The bioactivity of microglia modulated by IL-12 was examined and death receptors 4 and 5 were detected on cancerous cells. The effects of IL-12 and AAV2/IL-12 on microglial cytoxoxicity were evaluated too. The results demonstrated human cell line DBTRG, surgical specimen of GBM, and rat astrocyte expressed GFP quite well. Tremendous IL-12 secretion was detected in DBTRG, RG2, and astrocyte after transfection of AAV2/IL-12. TRAIL releasing and phagocytotic activity of microglia were significant, increasing (p<0.05) after the stimulation of IL-12. DR4 and DR5 were expressed in all of the examined GBM cells. MTT assay of microglial cytotoxicity elicited significant increase (p<0.05) when the IL-12 protein or RG2-secreting IL-12 could have contact with microglial cells. Conclusively, AAV2 is an effective vector in transferring therapeutic genes such as IL-12 to induce or enhance microglial anti-cancer activity.
Highlights
Interleukin-12Among the results of recent anti-cancer research, immuno-modulation with cytokines is one of the modalities with the most potential.[1,2,3,4] Many pro-inflammatory cytokines have been investigated and clarified for their anti-cancer effects and mechanisms
All of the 5 targeted cells types could be transfected by AAV type 2 (AAV2)/GFP and expressed GFP after 4 days incubation
The expression of GFP of human cell line DBTRG and glioblastoma multiforme (GBM) cells from excised specimen were near 100%, the RG2 cells displayed a lower expression rate of near 20% (Fig. 1)
Summary
Interleukin-12Among the results of recent anti-cancer research, immuno-modulation with cytokines is one of the modalities with the most potential.[1,2,3,4] Many pro-inflammatory cytokines have been investigated and clarified for their anti-cancer effects and mechanisms. Interleukin-12 (IL-12) exhibits the most power in enhancing either innate or adaptive responses for anti-cancer activity. IL-12 induces proliferation of hematopoietic progenitor cells and generation of IL-3 and stem-cell factors, along with stimulating a pre-activated natural killer cell, natural killer T cell, and cytotoxic T cell to increase in number and cytotoxicity and to secrete interferon- γ , granulocyte-macrophage colony-stimulating factor, tumor necrosis factor and IL-8. IL-12 may facilitate the TH1 pathway to promote the naïve T cells to effectiveness and becoming memory TH1 cells.[5] In anti-cancer activity, IL-12 has been demonstrated to stimulate NK cells or T cells to enhance anti-angiogenesis through secreting interferon-γ, to induce tumor cytotoxicity by secreting the family of tumor necrosis factor (TNF), and to promote tumor antigen-specific adaptive immunity through the TH1 pathway.[6]
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