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| Author(s): |
Ana Carolina Paschoalini Mafra
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia |
| Defense date: | 2021-09-01 |
| Examining board members: |
Sandra Martha Gomes Dias;
Valéria Helena Alves Cagnon;
Roger Chammas;
Tiago Goss dos Santos;
Thiago Mattar Cunha
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| Advisor: | Sandra Martha Gomes Dias; Marília Meira Dias |
| Abstract | |
Tumors consume large amounts of glucose and glutamine. The increase in glutamine consumption, in addition to contributing to the formation of biosynthetic precursors, is related to tumor progression. Glutaminases are encoded by two genes, GLS and GLS2. Both glutaminases are modular proteins, with domains notoriously involved in protein-protein interactions. GLS is oncogenic in several tumor types, while GLS2 plays an ambiguous role, being anti- or pro-tumor in different contexts. In a recent publication by the group, the protumorigenic role of GLS2 was proven in a group of breast tumors with increased expression of GLS2, via the ZEB/ERK/vimentin interaction axis. The aim of this work was to understand the role of GLS2 in crosstalk with immune system cells infiltrated in the microenvironment, and the role of this interaction for tumor progression in breast cancer. In silico analysis using the TCGA (The Cancer Genome Atlas) database revealed that tumors with high levels of GLS2 expression are depleted of lymphocytes and enriched in M2 macrophages, a subtype involved in tumor progression. In vitro co-culture assays with the human breast cancer line MCF7 with ectopic expression of GLS2 (GLS2+) with human monocytes revealed increased secretion of anti-inflammatory cytokines responsible for the polarization of M2 macrophages compared to control cells (Mock). Co-culture with murine breast tumor lineage EO771 Mock and GLS2+ altered the polarization phenotype of murine primary macrophages towards favoring the M2 phenotype, but this did not depend on GLS2 expression. GLS2 expression slowed down (and delayed) EO771 invasion; M2 didn't speed up this process in either Mock or GLS2+. EO771 GLS2+ orthotopic implants in syngeneic mice grew larger and heavier than Mock tumors. Histological analysis of the GLS2+ tumor sections revealed extensive regions of fibrosis, necrosis and hemorrhage in these tumors, compared to Mock tumors. Analysis of macrophage infiltration in tumor sections revealed a greater presence of M1 macrophages in Mock tumors than in GLS2+ tumors, while qualitatively, the presence of M2 appeared to be equal, suggesting a higher M2/M1 rate in GLS2+ tumors compared to Mock tumors. GLS2+ tumor sections also revealed increased endothelial cell labeling compared to control tumors. Finally, to identify GLS2 interaction partners, we performed co-immunoprecipitation followed by mass spectroscopy in the EO771 Mock strain /GLS2+ cultured in vitro. The identified proteins did not show any clear relationship and need further proof. We conclude that there is a relationship between the GLS2 isoenzyme and the content of macrophages infiltrating tumors with increased inflammatory response and tumor progression in breast cancer. However, this response, in the model studied, is not related to any specific crosstalk between the expression of GLS2 in cancer cells and the polarization profile of macrophages, being probably the product of a more complex relationship between the tumor and different cells (and/or other cell types) in the tumor microenvironment (AU) | |
| FAPESP's process: | 16/06625-0 - The mechanisms underlying the GLS2 pro-tumorigenic role |
| Grantee: | Ana Carolina Paschoalini Mafra |
| Support Opportunities: | Scholarships in Brazil - Doctorate (Direct) |