ABSTRACT
BACKGROUND: Metabolic reprogramming plays a key role in cancer progression and clinical outcomes; however, the patterns and primary regulators of metabolic reprogramming in colorectal cancer (CRC) are not well understood. AIM: To explore the role of nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) in promoting progression of CRC. METHODS: We evaluated the expression and function of dysregulated and survival-related metabolic genes using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes. Consensus clustering was used to cluster CRC based on dysregulated metabolic genes. A prediction model was constructed based on survival-related metabolic genes. Sphere formation, migration, invasion, proliferation, apoptosis and clone formation was used to evaluate the biological function of NOX4 in CRC. mRNA sequencing was utilized to explore the alterations of gene expression NOX4 over-expression tumor cells. In vivo subcutaneous and lung metastasis mouse tumor model was used to explore the effect of NOX4 on tumor growth. RESULTS: We comprehensively analyzed 3341 metabolic genes in CRC and identified three clusters based on dysregulated metabolic genes. Among these genes, NOX4 was highly expressed in tumor tissues and correlated with worse survival. In vitro, NOX4 overexpression induced clone formation, migration, invasion, and stemness in CRC cells. Furthermore, RNA-sequencing analysis revealed that NOX4 overexpression activated the mitogen-activated protein kinase-MEK1/2-ERK1/2 signaling pathway. Trametinib, a MEK1/2 inhibitor, abolished the NOX4-mediated tumor progression. In vivo, NOX4 overexpression promoted subcutaneous tumor growth and lung metastasis, whereas trametinib treatment can reversed the metastasis. CONCLUSION: Our study comprehensively analyzed metabolic gene expression and highlighted the importance of NOX4 in promoting CRC metastasis, suggesting that trametinib could be a potential therapeutic drugs of CRC clinical therapy targeting NOX4.
ABSTRACT
BACKGROUND: T cell immunoglobulin and mucin domain-containing protein 3 (TIM3) is a vital immune checkpoint that regulates the immune response. However, the specific role of TIM3 in patients with colorectal cancer (CRC) have rarely been studied. In this study, we investigated the effect of TIM3 on CD8+ T cells in CRC and explored the mechanism of TIM3 regulation in tumor microenvironment (TME). METHODS: Peripheral blood and tumor tissues of patients with CRC were collected to evaluate TIM3 expression using flow cytometry. Cytokines in the serum of healthy donors and patients with early- and advanced-stage CRC were screened using a multiplex assay. The effects of interleukin-8 (IL8) on TIM3 expression on CD8+ T cells were analyzed using cell incubation experiments in vitro. The correlation between TIM3 or IL8 and prognosis was verified using bioinformatics analysis. RESULTS: TIM3 expression on CD8+ T cells was obviously reduced in patients with advanced-stage CRC, whereas a lower TIM3 expression level was associated with poorer prognosis. Macrophage-derived IL8, which could inhibit TIM3 expression on CD8+ T cells, was significantly increased in the serum of patients with advanced CRC. In addition, the function and proliferation of CD8+ and TIM3+CD8+ T cells were inhibited by IL8, which was partly depending on TIM3 expression. The inhibitory effects of IL8 were reversed by anti-IL8 and anti-CXCR2 antibodies. CONCLUSIONS: In summary, macrophages-derived IL8 suppresses TIM3 expression on CD8+ T cells through CXCR2. Targeting the IL8/CXCR2 axis may be an effective strategy for treating patients with advanced CRC.
