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Down Regulation of c-FLIPL Enhance PD-1 Blockade Efficacy in B16 Melanoma
Yao Wang1,2, Jing-Jing Li1, Hong-Jun Ba3
1Biotherapy Center, Sun Yat-sen University Cancer Center, Guangzhou, China.
Abstract:
Immune checkpoint blockade of programmed cell death protein 1 (PD-1) had an impressive long-lasting effect in a portion of advanced-stage melanoma patients, however, this therapy failed to induce responses in several patients; how to increase the objective response rate is very important. Cellular FLICE-inhibitory protein (c-FLIP) could inhibit apoptosis directly at the death-inducing signaling complex of death receptors and is also considered to be the main cause of immune escape. The overexpression of c-FLIPL occurs frequently in melanoma and its expression is associated with the prognosis. We found that the level of c-FLIPL expression was associated with the PD-1 blockade response rate in melanoma patients. Thus, we performed this research to investigate how c-FLIPL regulates immunotherapy in melanoma. We demonstrate that down regulation of c-FLIPL enhances the PD-1 blockade efficacy in B16 melanoma tumor model. Down regulation of c-FLIPL could increase the tumor apoptosis and enhance the antitumor response of T cells in the lymphocyte tumor cells co-culture system. Moreover, knockdown of c-FLIPL could decrease the expression of PD-L1 and recruit more effector T cells in the tumor microenvironment. Our results may provide a new combined therapeutic target for further improving the efficacy of PD-1 blockade in melanoma.
Insights
Downregulating cellular FLICE-inhibitory protein (c-FLIP) enhances programmed cell death protein 1 (PD-1) blockade efficacy in melanoma. This approach increases tumor apoptosis and T cell response, potentially improving immunotherapy outcomes.
Area of Science:
- Immunology
- Oncology
- Molecular Biology
Background:
- Immune checkpoint inhibitors targeting programmed cell death protein 1 (PD-1) show efficacy in advanced melanoma but not all patients.
- Cellular FLICE-inhibitory protein (c-FLIP) overexpression is common in melanoma and linked to poor prognosis, potentially mediating immune escape by inhibiting apoptosis.
Purpose of the Study:
- To investigate the role of c-FLIP in regulating immunotherapy response in melanoma.
- To determine if targeting c-FLIP can enhance the efficacy of PD-1 blockade in melanoma treatment.
Main Methods:
- Utilized a B16 melanoma tumor model to assess the effects of c-FLIP downregulation on PD-1 blockade.
- Employed a co-culture system of lymphocytes and tumor cells to evaluate T cell-mediated antitumor responses.
- Analyzed changes in tumor apoptosis, PD-L1 expression, and T cell infiltration in the tumor microenvironment.
Main Results:
- Downregulation of c-FLIP significantly enhanced the efficacy of PD-1 blockade in the B16 melanoma model.
- Reduced c-FLIP levels led to increased tumor apoptosis and improved T cell antitumor responses.
- Knockdown of c-FLIP decreased PD-L1 expression and promoted the recruitment of effector T cells into the tumor microenvironment.
Conclusions:
- Cellular FLICE-inhibitory protein (c-FLIP) plays a critical role in modulating the response to PD-1 blockade in melanoma.
- Targeting c-FLIP represents a promising strategy to overcome resistance and improve the effectiveness of PD-1-based immunotherapy in melanoma patients.
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