Thesis (Ph.D.) - Cairo University - National Cancer Institute - Department of Cancer Biology

Background: Breast cancer is the most commonly diagnosed cancer and it is the first cause of cancer death among females worldwide. So new strategies are urgently needed, and the challenge for the future will most likely be the development of individualized therapies that specifically target each patient's tumor. Objective: This study had attempted to optimize the conditions for antigen loading with Dendritic cells (DCs). to produce a therapeutic cancer vaccine based on a whole viable tumor cells. As the fundamental aim of this work is to generate cytotoxic T cell response to tumor-associated antigens (TAAs). Methods: DCs were isolated from breast cancer patients of different types, and from age and sex matched healthy controls. Immature DCs were primed by whole viable Michigan Cancer Foundation-7 (MCF-7) breast cancer cells, then testing its efficacy through activation of T cell subsets (CTL and TH), the latters were evaluated by their cytotoxicity on MCF-7 breast cancer cells. Results: There was a significant increase in the expression of CD83+, CD86+ and their co-expression on DCs (P value <0.001). Also whole viable tumor cell immunizations resulted in polyvalent stimulation of both CD4+ Th cells (P value <0.001), and CD8+ CTLs (P value <0.001). Increased secretion of IFN-Þ by reactive tumor antigen specific CD4+ T cells was clearly observed (P value <0.001). Another important feature of effective DC maturation and activation was the significant increase in the secretion of IL12 (P value <0.001). Also There was a significant decrease in the expression of CD4+25+ and CD4+ 25+ Foxp3+ T regulatory cells (P value <0.001), by immunophenotyping. Moreover, there was a significant decrease in the level of FOXP3 protein (P value <0.001). That was confirmed by a significant down-regulation of its gene expression by quantitative real time PCR (P value <0.001). Also, there was a significant increase in the level of Lactate dehydrogenase (LDH) (P value <0.001), released from the tumor cells. Indicating a marked cytotoxicity of CTL on tumor cells

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