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Purpose: Angiogenesis actively contributes to tumor growth and metastasis. MACC1 was reported to be associated with tumor progression. In the present study, we aimed to investigate the expression and role of MACC1 in cholangiocarcinoma (CCA) and its correlation with angiogenesis.
Patients and methods: We investigated the expression and correlation of MACC1 and VEGFA in The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) datasets and in 7 paired frozen CCA and matched paracarcinoma tissues. Immunohistochemistry (IHC) was used to examine MACC1 and VEGFA expression as well as microvessel density (MVD) in 122 paraffin-embedded CCA samples. Western blotting, real-time qPCR and ELISA were performed to investigate the effect of MACC1 knockdown on VEGFA expression and secretion in CCA cells. Subsequently, we collected conditioned medium from cells with MACC1 knockdown and used it in angiogenesis assays.
Results: The expression levels of both MACC1 and VEGFA were significantly upregulated in the TCGA and GEO datasets and in the 7 paired frozen CCA tissues compared to the matched paracarcinoma tissues, and MACC1 was significantly correlated with VEGFA. IHC showed that high expression of MACC1 and VEGFA was significantly correlated with lymph node metastasis (P <0.05 and P <0.01) and worse survival (P <0.01, P <0.05) in patients with CCA. We further verified that MACC1 was significantly correlated with VEGFA (P <0.01) and MVD (P <0.01) in clinical samples. Western blotting, real-time qPCR and ELISA results showed that MACC1 knockdown in CCA cells significantly decreased the protein and mRNA expression of VEGFA and reduced the VEGFA concentration in conditioned medium. Moreover, angiogenesis assays showed that conditioned medium from CCA cells with MACC1 knockdown decreased the number of tubes formed. 
Conclusion: Our results indicate that MACC1 and VEGFA expression are upregulated in CCA. Moreover, MACC1 is an independent predictor of overall survival and facilitates angiogenesis in CCA by upregulating of VEGFA.
Keywords: microvessel density, TCGA, GEO, prognosis, carcinoma