Fig. 7: Schematic representation of the proposed hypothesis: elevated AZIN1-driven polyamine production promotes osteosarcoma proliferation and impairs immunotherapy efficacy. | Cell Death & Disease

Fig. 7: Schematic representation of the proposed hypothesis: elevated AZIN1-driven polyamine production promotes osteosarcoma proliferation and impairs immunotherapy efficacy.

From: AZIN1-dependent polyamine synthesis accelerates tumor cell cycle progression and impairs effector T-cell function in osteosarcoma

Fig. 7: Schematic representation of the proposed hypothesis: elevated AZIN1-driven polyamine production promotes osteosarcoma proliferation and impairs immunotherapy efficacy.The alternative text for this image may have been generated using AI.

In osteosarcoma cells, increased levels of arginine and AZIN1 upregulate the metabolism of arginine into polyamines through AZIN1-mediated activation of ornithine decarboxylase 1 (ODC1). This enhancement in polyamine production supports tumor cell proliferation and impedes the efficacy of immunotherapy. Conversely, when polyamine synthesis is inhibited—either by AZIN1 knockdown or through difluoromethylornithine (DFMO)-mediated inhibition of ODC1-polyamine levels decrease, leading to cell cycle arrest and the upregulation of human leukocyte antigen (HLA) expression and T cell-activating cytokines. These changes augment the cytotoxic efficacy of TCR-engineered T cells against osteosarcoma cells.

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