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Abstract Lymph node (LN) metastasis is one of the key prognostic factors in bladder cancer, but its underlying mechanisms remain unclear. Here, we found that elevated expression of WD repeat domain 4 (WDR4) in bladder cancer correlated with worse prognosis. WDR4 can promote the LN metastasis and proliferation of bladder cancer cells. Mechanistic studies showed that WDR4 can promote the nuclear localization of DEAD-box helicase 20 (DDX20) and act as an adaptor to bind DDX20 and Early growth response 1 (Egr1), thereby inhibiting Egr1-promoted transcriptional expression of arrestin beta 2 (ARRB2) and ultimately contributing to the progression of bladder cancer. Immunohistochemical analysis confirmed that WDR4 expression is also an independent predictor of LN metastasis in bladder cancer. Our results reveal a novel mechanism of LN metastasis and progression in bladder cancer and identify WDR4 as a potential therapeutic target for metastatic bladder cancer.

Abstract The mechanisms underlying the effects of cancer-associated fibroblasts (CAFs) on cancer stemness and tumor progression in renal cell carcinoma (RCC) have not been elucidated yet. In the present study, we found that the enrichment of CAFs was positively associated with tumor progression and cancer stemness in RCC. Further investigation revealed that CAFs could enhance cancer stemness through delivering exosomes to RCC cells, and miR-181d-5p was identified as the critical exosomal miRNA in CAF-secreted exosomes by small RNA sequencing and subsequent screening assays. Mechanistically, exosomal miR-181d-5p transferred from CAFs to RCC cells directly suppressed the expression of ring finger protein 43 (RNF43) and activated Wnt/β-catenin signaling pathway, thus promoted cancer stemness and tumor progression. Overexpression of RNF43 strongly suppressed stemness properties and the effects could be reverted by miR-181d-5p. Overall, our findings revealed a crucial mechanism by which CAF-secreted exosomal miRNAs to enhance cancer stemness and thus promote RCC progression, suggesting a new avenue based on CAF-secreted miRNAs for more effective targeted therapies.

Abstract Lymph node (LN) metastasis is associated with unfavorable prognosis of bladder cancer (BCa). Although lymphangiogenesis is functionally important in LN metastasis of tumors, the potential mechanism in BCa remains unclear. Here, we clarified a regulatory mechanism of circRNA-mediated lymphangiogenesis and LN metastasis in BCa based on next-generation sequencing data. We revealed that circDHTKD1 was positively associated with LN metastasis and significantly upregulated in BCa. By analyzing the co-expression patterns of circDHTKD1 and differentially expressed mRNAs, we identified that circDHTKD1 facilitated lymphangiogenesis by upregulating CXCL5. Mechanistically, circDHTKD1 directly interacted with miR-149-5p, and antagonized the repression of miR-149-5p on CXCL5. Furthermore, circDHTKD1-induced CXCL5 expression recruited and activated neutrophils, which participated in lymphangiogenesis by secreting VEGF-C. Our study supports circDHTKD1 as a promising diagnostic and therapeutic target for LN metastasis in BCa.