Impact of the AMPK signaling pathway on the modulation of the antitumor immune response by T cells CD4+ and CD8+

Author(s)

Amanda Campelo Lima Melo Feitosa

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI)
• Defense date: 2019-10-17

Examining board members

Niels Olsen Saraiva Câmara; Gilberto de Castro Junior; Ildefonso Alves da Silva Júnior; Elaine Guadelupe Rodrigues

• Advisor: Niels Olsen Saraiva Câmara

Abstract

It has been reported that metformin treatment interferes with the development and progression of tumors and, in addition to direct action through changes in metabolism, it is possible that alterations impact the activity of cells of the immune system, as well as the tumor cell, leading to modifications on the tumor microenvironment that may or may not be beneficial. Considering that the effect of metformin results, in part, by the activation of AMPK and mTOR pathways, we hypothesized that the absence of these pathways in CD4&#43and CD8&#43 T cells would influence the progression of murine melanoma B16F10. Therefore, the purpose of this study is to evaluate whether the impact of AMPK metabolic pathway on T cells is able to cause modifications on tumor development process of the murine melanoma model, as well as to understand what are the effector immune mechanisms involved in this process. In previous work already published by our group, we demonstrated that in vivo metformin has a significant antitumor effect. We have seen that this effect is partially dependent on the immune system and that T cells plays an important role in this protection. Based on this, we used animals of the Cre-lox system that did not have AMPK (CD4cre&#43AMPKfl/fl) and Raptor (CD4cre&#43Raptorfl/fl) in the CD4&#43 and CD8&#43 T cells. We have seen that CD4cre&#43AMPKfl/fl animals are protected from tumor development in the two melanoma models analyzed and that the tumor lungs of these animals have a smaller CD4&#43, CD4&#43PD1&#43, CD8&#43PD-1&#43 T cell population, a larger population of CD8&#43IFN-&#43 T cells, as well as a smaller population of CD4&#43 T cells in the spleen and primary tumor of these animals. We also verified a higher relative expression of the tnf- and hk-2 genes in the lung of CD4cre&#43AMPKfl/fl animals with tumor. As for the CD4cre&#43Raptorfl/fl animals, we observed that they also have a lower development of lung metástases and a longer survival than control animals. We also demonstrated that AMPK deletion cannot change T cells proliferation and cannot interfere on the differentiation of these cells into Tregs cells of the tested concentrations, but treatment of metformin-activated CD4&#43 T cells was able to modify proliferation of these cells of independently AMPK in T cells as well as interfered Tregs cell differentiation only in CD4cre&#43AMPKfl/fl animals. Regarding metabolism, we verified that deletion of AMPK in T cells decreased mitochondrial mass and membrane potential of activated CD4&#43 T cells, but did not interfere cellular respiration of these cells (OXPHOS). When we treated these cells with metformin, we noted that CD4&#43 T cells of both animals do less OXPHOS, demonstrating that this effect is independent of the AMPK pathway in T cells, in addition to reducing AMPK-dependent mitochondrial mass in T cells. Together, these results suggests that AMPK and mTORC1 in T cells is prejudicial in the context of murine melanoma B16F10 and that deletion of AMPK in CD4&#43 and CD8&#43 T cells changes immune and metabolic aspects. (AU)

• FAPESP's process: 15/15062-7 - Role of AMPK pathway in the modulation of anti-tumor immune response by T lymphocytes (CD4 and CD8)
• Grantee: Amanda Campelo Lima de Melo
• Support Opportunities: Scholarships in Brazil - Doctorate