Downregulation of Dual-specificity phosphatase 9 promotes tumor progression and contributes to poor prognosis in colorectal cancer

Abstract Background Dual-specificity phosphatase 9 (DUSP9) belongs to the dual-specificity protein phosphatase subfamily. Recently, increasing attention has been paid on the role of DUSP9 in a variety of cancers. However, its functional role in tumor development is still unclear, especially in colorectal cancer (CRC). Methods The functional role of DUSP9 in inhibiting the progression of CRC was verified both in vivo and in vitro using colony formation assay, EdU incorporation assay, wound healing assay, nude mice xenograft model, and et al. RNA-seq was performed to assess the gene expression profiling in SW480 cells with DUSP9 stable knockdown and shControl cells. Bisulfite sequencing (BSE) was performed to reveal methylation status of CpG island in promoter of DUSP9. Results DUSP9 was significantly down regulated in tumor tissues compared with peritumor tissues. Moreover, low DUSP9 expression in CRC was closely associated with tumor size, depth of invasion and advanced TNM stage, indicating that DUSP9 may be involved in the progression of CRC. Kaplan–Meier survival analysis showed that the overall survival (OS) and recurrence-free survival (RFS) of patients with low expression of DUSP9 were significantly shorter than that of patients with high expression of DUSP9. Functional study revealed that DUSP9 inhibited tumor migration, invasion and metastasis both in vitro and in vivo . Mechanistically, low expression of DUSP9 in CRC was caused by the upregulation of miR-1246 and hypermethylation status of CpG island in promoter of DUSP9. Conclusion Our findings demonstrate that DUSP9 plays a critical role in the progression of CRC and therapeutic intervention to increase the expression or activity of DUSP9 may be a potential target for CRC treatment in the future.