رسائل ماجيستير
English
2024
Mitochondrial Control of Tumorigenicity and Immunogenicity of Colorectal Cancer
Basel Al-Ramadi, Maram Esam Eldin Ahmed , Maria Fernandez Cabezudo
كلية الطب والعلوم الصحية-جامعة الإمارات العربية المتحدة · الامارات
The Methylation-controlled J protein (MCJ), also known as DNAJC15, serves as an endogenous negative regulator of mitochondrial respiration. MCJ plays a crucial role in cellular bioenergetics by regulating cellular metabolism, and its expression is inversely proportional to the extent of mitochondrial ATP production. In the current study, we aimed to investigate the relationship between MCJ expression and the tumorigenicity and immunogenicity of colon adenocarcinoma. To this aim, we utilized MCJ knockout (KO) mice to assess the impact of tumor-extrinsic MCJ expression in host cells, particularly immune cells, on anti-tumor responses. Comparing the growth of MCJ-expressing cancer cells in wild-type vs. MCJ KO mice revealed a decreased level of cancer cell growth in MCJ KO mice, which was shown to be due to enhanced anti-tumor responses in KO mice compared to wild-type C57BL/6 mice. To study the role of tumor-intrinsic MCJ expression, we generated MCJ-deficient cancer cell lines using shRNA and performed a comprehensive comparison of their characteristics with MCJ-expressing parental cells. Global transcriptomic analysis using RNASeq revealed profound alterations in gene expression between MCJ-expressing parental and MCJ-deficient transfectant cells. Based on the differential genetic signatures, we could identify functional changes in several immune-related pathways, including the interferon gamma/alpha signaling, TNF-α signaling and JAK-STAT signaling pathways, as well as in epithelial-mesenchymal transition. Further characterization of MCJ-deficient cells revealed that while they exhibited similar growth characteristics to MCJ-positive cells in vitro, their in vivo growth was dramatically curtailed in wild-type C57BL/6 mice. In contrast, the growth of MCJ-deficient cancer cells was indistinguishable from parental cells in athymic, T-cell deficient, mice. Investigation of the tumor microenvironment by immunohistochemistry and flow cytometry revealed significant alterations in infiltrating immune cells indicative of increased immunogenicity, which render them more susceptible to host's anti-tumor immune responses. To gain further insight into the underlying mechanisms, we carried out RNASeq analysis of excised tumor tissue of MCJ-expressing and MCJ-deficient cancer cells. RNASeq profiling of tumors showed a dramatic alteration in metabolic programming within the MCJ-deficient tumors indicating a shift from a predominantly glycolysis-driven hypoxic tumor microenvironment to less hypoxic conditions that are reliant on the utilization of the oxidative phosphorylation pathway. This fundamental change is underpinned by alterations in many immune-related pathways that function to enhance anti-tumor immune responsiveness. These novel findings highlight the dual role of MCJ protein in regulating the immunogenicity of cancer cells and the efficacy of anti-tumor immune responses. By elucidating the impact of MCJ on cancer cell behavior and host immune cell function, our study underscores the connection between cellular metabolism, tumorigenesis, and anti-tumor immune responses. These insights enhance our understanding of cancer biology and hold promise for the development of novel therapeutic strategies targeting metabolic reprogramming within tumors.