RESUMO
Cancer cells have an altered metabolic state that supports their growth, for example, aerobic glycolysis, known as the Warburg effect. Colorectal cancer cells have been reported to exhibit the Warburg effect and mainly rely on glycolysis for progression and have dysfunctional mitochondria. So far, how mitochondrial function influences the properties of colorectal cancer cells is unclear. Here, we demonstrated that mitochondria maintain histone acetylation, in particular acetylated histone H3 lysine 27 (H3K27ac), a surrogate epigenomic marker of active super-enhancers, in colorectal cancer cells. Immunohistochemistry was used on human colorectal adenocarcinoma specimens and showed that mitochondrial mass and H3K27ac marks were increased in adenocarcinoma lesions compared with adjacent non-neoplastic mucosa. Immunoblotting after using inhibitors of the mitochondrial respiratory complex or mitochondrial DNA-depleted human colorectal cancer cells revealed that mitochondria maintained pan-histone acetylation and H3K27ac marks. Notably, anchorage-independent growth, a feature of cancer, increased mitochondrial mass and H3K27ac marks in human colorectal cancer cells. These findings indicate that mitochondria in human colorectal cancer cells are not dysfunctional, as formerly believed, but function as inducers of histone acetylation. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Assuntos
Adenocarcinoma/metabolismo , Neoplasias Colorretais/metabolismo , Histonas/metabolismo , Mitocôndrias/metabolismo , Processamento de Proteína Pós-Traducional , Acetilação , Adenocarcinoma/genética , Adenocarcinoma/patologia , Proliferação de Células , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , DNA Mitocondrial/genética , DNA Mitocondrial/metabolismo , Epigênese Genética , Regulação Neoplásica da Expressão Gênica , Células HCT116 , Humanos , Mitocôndrias/genética , Mitocôndrias/patologia , Efeito Warburg em OncologiaRESUMO
BACKGROUND: The mechanisms underlying metastasis of colorectal cancer (CRC) remain unclear. C14orf159 is a mitochondrial matrix protein converting D-glutamate to 5-oxo-D-proline. Other metabolic functions of C14orf159, especially on mitochondrial metabolism, and its contribution to CRC metastasis, are not elucidated. METHODS: Metabolome analysis by gas chromatography-mass spectrometry, RNA-sequencing analysis, flow cytometry, migration and invasion assay, sphere-formation assay using C14orf159-knockout and -stable expressing cells, immunohistochemistry of C14orf159 in human CRC specimens, and xenograft experiments using Balb/c nude mice were conducted. RESULTS: C14orf159 maintained the mitochondrial membrane potential of human CRC cells, and its involvement in amino acid and glutathione metabolism was demonstrated. In human CRC specimens, a decrease in C14orf159 expression at the invasive front of the tumour and in metastasis was determined. C14orf159 was also shown to attenuate the migration, invasion, and spheroid growth of CRC cells in vitro and colorectal tumour growth and metastasis in vivo. Mechanistically, C14orf159 reduced the expression of genes involved in CRC metastasis, including members of the Wnt and MMP family, by maintaining the mitochondrial membrane potential. CONCLUSIONS: Our findings link mitochondrial membrane potential to Wnt/ß-catenin signalling and reveal a previously unrecognised function of the mitochondrial matrix protein C14orf159 as a suppressor of CRC metastasis.
Assuntos
Neoplasias Colorretais/genética , Regulação Neoplásica da Expressão Gênica/genética , Proteínas Mitocondriais/metabolismo , Via de Sinalização Wnt/genética , beta Catenina/genética , Animais , Linhagem Celular Tumoral , Modelos Animais de Doenças , Feminino , Humanos , Camundongos , Metástase Neoplásica , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Soluble N-Ethylmaleimide Sensitive Factor Attachment Protein Receptor (SNARE) proteins are crucial for signal transduction and development in plants. Here, we investigate a Lotus japonicus symbiotic mutant defective in one of the SNARE proteins. When in symbiosis with rhizobia, the growth of the mutant was retarded compared with that of the wild-type plant. Although the mutant formed nodules, these exhibited lower nitrogen fixation activity than the wild type. The rhizobia were able to invade nodule cells, but enlarged symbiosomes were observed in the infected cells. The causal gene, designated LjSYP71 (for L. japonicus syntaxin of plants71), was identified by map-based cloning and shown to encode a Qc-SNARE protein homologous to Arabidopsis (Arabidopsis thaliana) SYP71. LjSYP71 was expressed ubiquitously in shoot, roots, and nodules, and transcripts were detected in the vascular tissues. In the mutant, no other visible defects in plant morphology were observed. Furthermore, in the presence of combined nitrogen, the mutant plant grew almost as well as the wild type. These results suggest that the vascular tissues expressing LjSYP71 play a pivotal role in symbiotic nitrogen fixation in L. japonicus nodules.
