Doublecortin-like kinase 1 promotes stem cell-like properties through the Hippo-YAP pathway in prostate cancer

<b>Background:</b> Doublecortin-like kinase 1 (DCLK1) has been revealed to be involved in modulating cancer stemness and tumor progression, but its role in prostate cancer (PCa) remains obscure. Castration-resistant and metastatic PCa exhibit aggressive behaviors, and current therapeutic approaches have shown limited beneficial effects on the overall survival rate of patients with advanced PCa. This study aimed to investigate the biological role and potential molecular mechanism of DCLK1 in the progression of PCa. <b>Methods:</b> The role of DCLK1 in maintaining PCa stem cell-like properties was explored via gain- and loss-of-function studies, including colony formation assays, sphere formation assays and measurement of stemness-related marker expression. A set of transcriptomic data for patients with PCa was downloaded from The Cancer Genome Atlas to analyze the correlations between DCLK1 and Hippo pathway gene expression. The mechanism by which DCLK1 regulates Hippo signaling and cancer stemness was further investigated <i>in vitro</i> by methods such as Western blot analysis, quantitative real-time PCR analysis, immunofluorescence staining, and luciferase reporter assays and <i>in vivo</i> by animal studies. <b>Results:</b> The gain- and loss-of-function studies demonstrated that upregulating DCLK1 promoted but downregulating DCLK1 suppressed aspects of the PCa stem cell-like phenotype, including colony formation, sphere formation and the expression of stemness-related markers (c-Myc, OCT4, CD44, NANOG, SOX2, and KLF4). Importantly, bioinformatics analysis indicated that DCLK1 is closely correlated with the Hippo signaling pathway in PCa. Further <i>in vitro</i> assays revealed that DCLK1 inhibits the Hippo signaling pathway, leading to yes-associated protein (YAP) activation via large tumor suppressor homolog 1 (LATS1). Moreover, the effect of DCLK1 on abolishing stemness traits in PCa was observed after treatment with verteporfin, a small molecule inhibitor of YAP. Consistent with the <i>in vitro</i> findings, the <i>in vivo</i> findings confirmed that DCLK1 promoted the tumorigenicity and stem cell-like traits of PCa cells via Hippo-YAP signaling. <b>Conclusion:</b> DCLK1 promotes stem cell-like characteristics by inducing LATS1-mediated YAP signaling activation, ultimately leading to PCa tumor growth and progression. Thus, our findings identify an attractive candidate for the development of cancer stem cell-targeted therapies to improve treatment outcomes in advanced PCa.