Macrophage Migration Inhibitory Factor (MIF) Upregulates CXCR7 and Contributes to Chemotherapy Resistance in Colorectal Cancer.

Colorectal cancer is one of the most common malignant tumors worldwide, with high incidence and mortality rates making it a focus of research. Chemotherapy is a primary treatment modality for colon cancer, but chemotherapy resistance severely impacts treatment efficacy. MIF has been found to promote tumor progression and resistance in various cancers. This study aims to investigate the role of MIF in chemotherapy resistance in colon cancer and its potential mechanisms, particularly through the upregulation of CXCR7 expression, affecting the metabolism and drug sensitivity of colon cancer cells. The expression levels of MIF in colon cancer tissues and its association with patient prognosis were evaluated by analyzing TCGA and HPA data. Subsequently, the expression levels of MIF in colon cancer cell lines and resistant cell lines were detected by qRT-PCR and immunohistochemistry, and the effect of MIF on oxaliplatin sensitivity was assessed. The impact of MIF on the metabolic activity of colon cancer cells was measured using a cellular energy metabolism analyzer. Further experiments explored the mechanism by which MIF affects the metabolic activity of colon cancer cells through the upregulation of CXCR7 expression, and the role of CTCF in regulating CXCR7 transcription was validated by silencing CTCF. Finally, the effect of MIF on drug sensitivity of colon cancer cells was verified in a mouse xenograft tumor model. In this study, we found that the expression of MIF in colon cancer tissues was significantly higher than in normal tissues, and high MIF expression was associated with poor prognosis in patients. The expression levels of MIF in resistant colon cancer cell lines were significantly higher than in parental cell lines, and MIF overexpression significantly increased the resistance of colon cancer cells to oxaliplatin. Conversely, silencing MIF significantly reduced the IC50 value of resistant cells and increased apoptosis. MIF overexpression significantly increased the ECAR and OCR levels of colon cancer cells, while MIF knockdown significantly reduced these metabolic indicators. Further studies indicated that MIF affects the metabolic activity of colon cancer cells by upregulating CXCR7 expression. CTCF binding peaks at the CXCR7 promoter region and luciferase activity assays indicated that CTCF regulates CXCR7 transcription, and silencing CTCF significantly enhanced the sensitivity of colon cancer cells to oxaliplatin. In vivo experiments in mice showed that MIF silencing combined with oxaliplatin treatment significantly inhibited tumor growth and increased the necrotic area of tumor tissues. In conclusion, this study reveals the crucial role of MIF in chemotherapy resistance in colon cancer through the upregulation of CXCR7 expression, with CTCF playing an important regulatory role in this process. Our findings provide new theoretical insights and potential therapeutic targets for overcoming chemotherapy resistance in colon cancer. Future research should further explore the roles of MIF and CXCR7 in other types of cancers and the potential of MIF and CXCR7 as therapeutic targets.