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Abstract Heterogeneous extracellular vesicles (EVs) from various types of tumours are acknowledged for inducing the formation of pre‐metastatic “niches” in draining lymph nodes (LNs) to promote lymphatic metastasis. In order to identify the specific subpopulations of EVs involved, we performed high‐resolution proteomic analysis combined with nanoflow cytometry of bladder cancer (BCa) tissue‐derived EVs to identify a novel subset of tumour‐derived EVs that contain integrin α6 (ITGA6+EVs) and revealed the positive correlation of ITGA6+EVs with the formation of pre‐metastatic niche in draining LNs and lymphatic metastasis in multicentre clinical analysis of 820‐case BCa patients. BCa‐derived ITGA6+EVs induced E‐selectin (SELE)‐marked lymphatic remodelling pre‐metastatic niche and promoted metastasis in draining LNs through delivering cargo circRNA‐LIPAR to lymphatic endothelial cells in vivo and in vitro. Mechanistically, LIPAR linked ITGA6 to the switch II domain of RAB5A and sustained RAB5A GTP‐bound activated state, thus maintaining the production of ITGA6+EVs loaded with LIPAR through endosomal trafficking. ITGA6+EVs targeted lymphatic vessels through ITGA6‐CD151 interplay and released LIPAR to induce SELE overexpression‐marked lymphatic remodelling pre‐metastatic niche. Importantly, we constructed engineered‐ITGA6 EVs to inhibit lymphatic pre‐metastatic niche, which suppressed lymphatic metastasis and prolonged survival in preclinical models. Collectively, our study uncovers the mechanism of BCa‐derived ITGA6+EVs mediating pre‐metastatic niche and provides an engineered‐EV‐based strategy against BCa lymphatic metastasis.

Abstract Background Cancer‐associated fibroblasts (CAFs) play a vital role in facilitating tumor progression through extensive reciprocal interplay with cancer cells. Tumor‐derived extracellular vesicles (EVs) are the critical mediators involved in the crosstalk between cancer cells and stromal cells, contributing to the metastasis of cancers. Yet, the biological mechanisms of tumor‐derived EVs in triggering CAFs phenotype to stimulate the lymph node (LN) metastasis of bladder cancer (BCa) are largely unknown. Here, we aimed to explore the effects and molecular mechanisms of tumor‐derived EV‐mediated CAFs phenotype in regulating BCa LN metastasis. Methods The high‐throughput sequencing was utilized to identify the crucial long non‐coding RNA (lncRNA) associated with CAF enrichment in BCa. The functional role of the transition of fibroblasts to CAFs induced by LINC00665‐mediated EVs was investigated through the in vitro and in vivo assays. Chromatin isolation by RNA purification assays, fluorescence resonance energy transfer assays, cytokine profiling and patient‐derived xenograft (PDX) model were performed to explore the underlying mechanism of LINC00665 in the LN metastasis of BCa. Results We found that CAFs are widely enriched in the tumor microenvironment of BCa, which correlated with BCa lymphangiogenesis and LN metastasis. We then identified a CAF‐associated long non‐coding RNA, LINC00665, which acted as a crucial mediator of CAF infiltration in BCa. Clinically, LINC00665 was associated with LN metastasis and poor prognosis in patients with BCa. Mechanistically, LINC00665 transcriptionally upregulated RAB27B expression and induced H3K4me3 modification on the promoter of RAB27B through the recruitment of hnRNPL. Moreover, RAB27B‐induced EVs secretion endowed fibroblasts with the CAF phenotype, which reciprocally induced LINC00665 overexpression to form a RAB27B‐HGF‐c‐Myc positive feedback loop, enhancing the lymphangiogenesis and LN metastasis of BCa. Importantly, we demonstrated that blocking EV‐transmitted LINC00665 or HGF broke this loop and impaired BCa lymphangiogenesis in a PDX model. Conclusion Our study uncovers a precise mechanism that LINC00665 sustains BCa LN metastasis by inducing a RAB27B‐HGF‐c‐Myc positive feedback loop between BCa cells and fibroblasts, suggesting that LINC00665 could be a promising therapeutic target for patients with LN metastatic BCa.

Abstract Lymph node (LN) metastasis is one of the predominant metastatic routes of non-small cell lung cancer (NSCLC) and is considered as a leading cause for the unsatisfactory prognosis of patients. Although lymphangiogenesis is well-recognized as a crucial process in mediating LN metastasis, the regulatory mechanism involving lymphangiogenesis and LN metastasis in NSCLC remains unclear. In this study, we employed high-throughput sequencing to identify a novel circular RNA (circRNA), circTLCD4-RWDD3, which was significantly upregulated in extracellular vesicles (EVs) from LN metastatic NSCLC and was positively associated with deteriorated OS and DFS of patients with NSCLC from multicenter clinical cohort. Downregulating the expression of EV-packaged circTLCD4-RWDD3 inhibited lymphangiogenesis and LN metastasis of NSCLC both in vitro and in vivo. Mechanically, circTLCD4-RWDD3 physically interacted with hnRNPA2B1 and mediated the SUMO2 modification at K108 residue of hnRNPA2B1 by upregulating UBC9. Subsequently, circTLCD4-RWDD3-induced SUMOylated hnRNPA2B1 was recognized by the SUMO interaction motif (SIM) of ALIX and activated ALIX to recruit ESCRT-III, thereby facilitating the sorting of circTLCD4-RWDD3 into NSCLC cell-derived EVs. Moreover, EV-packaged circTLCD4-RWDD3 was internalized by lymphatic endothelial cells to activate the transcription of PROX1, resulting in the lymphangiogenesis and LN metastasis of NSCLC. Importantly, blocking EV-mediated transmission of circTLCD4-RWDD3 via mutating SIM in ALIX or K108 residue of hnRNPA2B1 inhibited the lymphangiogenesis and LN metastasis of NSCLC in vivo. Our findings reveal a precise mechanism underlying SUMOylated hnRNPA2B1-induced EV packaging of circTLCD4-RWDD3 in facilitating LN metastasis of NSCLC, suggesting that EV-packaged circTLCD4-RWDD3 could be a potential therapeutic target against LN metastatic NSCLC.

Abstract Background Circular RNAs (circRNAs) circularized by back-splicing of pre-mRNA are widely expressed and affected the proliferation, invasion and metastasis of bladder cancer (BCa). However, the mechanism underlying circRNA biogenesis in mediating the distant metastasis of BCa still unexplored. Methods RNA sequencing data between BCa and normal adjacent tissues was applied to identify the differentially expressed circRNAs. The functions of circNIPBL in BCa were investigated via a series of biochemical experiments. The Clinical significance of circNIPBL was examined in a cohort of larger BCa tissues. Results In the present study, we identified a novel circRNA (hsa_circ_0001472), circNIPBL, which was significantly upregulated and had great influence on the poor prognosis of patients with BCa. Functionally, circNIPBL promotes BCa metastasis in vitro and in vivo. Mechanistically, circNIPBL upregulate the expression of Wnt5a and activated the Wnt/β-catenin signaling pathway via directly sponged miR-16-2-3p, leading to the upregulation of ZEB1, which triggers the EMT of BCa. Moreover, we revealed that ZEB1 interacted with the flanking introns of exons 2–9 on NIPBL pre-mRNA to trigger circNIPBL biogenesis, thus forming a positive feedback loop. Importantly, circNIPBL overexpression significantly facilitated the distant metastasis of BCa in the orthotopic bladder cancer model, while silencing ZEB1 remarkably blocked the effects of metastasis induced by circNIPBL overexpression. Conclusions Our study highlights that circNIPBL-induced Wnt signaling pathway activation triggers ZEB1-mediated circNIPBL biogenesis, which forms a positive feedback loop via the circNIPBL/miR-16-2-3p/Wnt5a/ZEB1 axis, supporting circNIPBL as a novel therapeutic target and potential biomarker for BCa patients. Graphical Abstract

Lymph node (LN) metastasis occurs frequently in pancreatic ductal adenocarcinoma (PDAC) and predicts poor prognosis for patients. The KRASG12D mutation confers an aggressive PDAC phenotype that is susceptible to lymphatic dissemination. However, the regulatory mechanism underlying KRASG12D mutation–driven LN metastasis in PDAC remains unclear. Herein, we found that PDAC with the KRASG12D mutation (KRASG12D PDAC) sustained extracellular vesicle–mediated (EV-mediated) transmission of heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1) in a SUMOylation-dependent manner and promoted lymphangiogenesis and LN metastasis in vitro and in vivo. Mechanistically, hnRNPA1 bound with SUMO2 at the lysine 113 residue via KRASG12D-induced hyperactivation of SUMOylation, which enabled its interaction with TSG101 to enhance hnRNPA1 packaging and transmission via EVs. Subsequently, SUMOylation induced EV-packaged-hnRNPA1 anchoring to the adenylate- and uridylate-rich elements of PROX1 in lymphatic endothelial cells, thus stabilizing PROX1 mRNA. Importantly, impeding SUMOylation of EV-packaged hnRNPA1 dramatically inhibited LN metastasis of KRASG12D PDAC in a genetically engineered KrasG12D/+ Trp53R172H/+ Pdx-1-Cre (KPC) mouse model. Our findings highlight the mechanism by which KRAS mutant–driven SUMOylation triggers EV-packaged hnRNPA1 transmission to promote lymphangiogenesis and LN metastasis, shedding light on the potential application of hnRNPA1 as a therapeutic target in patients with KRASG12D PDAC.

Abstract Background Patients with lymph node (LN)-positive pancreatic ductal adenocarcinoma (PDAC) have extremely poor survival rates. Circular RNAs (circRNAs), a newly discovered type of endogenous noncoding RNAs, have been proposed to mediate the progression of diverse types of tumors. However, the role and underlying regulatory mechanisms of circRNAs in the LN metastasis of PDAC remain unknown. Methods Next-generation sequencing was used to identify differentially expressed circRNAs between PDAC and normal adjacent tissues. In vitro and in vivo experiments were conducted to evaluate the functional role of circNFIB1. RNA pulldown and luciferase assays were performed to examine the binding of circNFIB1 and miR-486-5p. Results In the present study, we identified that a novel circRNA (circNFIB1, hsa_circ_0086375) was downregulated in PDAC and negatively associated with LN metastasis in PDAC patients. Functionally, circNFIB1 knockdown promoted lymphangiogenesis and LN metastasis of PDAC both in vitro and in vivo. Mechanistically, circNFIB1 functioned as a sponge of miR-486-5p, and partially reversed the effect of miR-486-5p. Moreover, circNFIB1 attenuated the oncogenic effect of miR-486-5p and consequently upregulated PIK3R1 expression, which further downregulated VEGF-C expression through inhibition of the PI3K/Akt pathway, and ultimately suppressed lymphangiogenesis and LN metastasis in PDAC. Conclusions Our findings provide novel insight into the underlying mechanism of circRNA-mediated LN metastasis of PDAC and suggest that circNFIB1 may serve as a potential therapeutic target for LN metastasis in PDAC. Graphical abstract

Abstract Background Patients with lymph node (LN) metastatic bladder cancer (BCa) present with extremely poor prognosis. BCa‐derived exosomes function as crucial bioactive cargo carriers to mediate the signal transduction in tumor microenvironment triggering tumor metastasis. However, the mechanisms underlying exosome‐mediated LN metastasis in BCa are unclear. Methods We conducted the high‐throughput sequencing to explore the expression profile of long noncoding RNA (lncRNA) in urinary exosomes (urinary‐EXO) from patients with BCa and further evaluated the clinical relevance of exosomal lncRNA BCYRN1 in a larger 210‐case cohort. The functional role of exosomal BCYRN1 was evaluated through the migration and tube formation assays in vitro and the footpad‐popliteal LN metastasis model in vivo. RNA pull‐down assays, luciferase assays, and actinomycin assays were conducted to detect the regulatory mechanism of exosomal BCYRN1. Results LncRNA BCYRN1 was substantially upregulated in urinary‐EXO from patients with BCa, and associated with the LN metastasis of BCa. We demonstrated that exosomal BCYRN1 markedly promoted tube formation and migration of human lymphatic endothelial cells (HLECs) in vitro and lymphangiogenesis and LN metastasis of BCa in vivo. Mechanistically, BCYRN1 epigenetically upregulated WNT5A expression by inducing hnRNPA1‐associated H3K4 trimethylation in WNT5A promoter, which activated Wnt/β‐catenin signaling to facilitate the secretion of VEGF‐C in BCa. Moreover, exosomal BCYRN1 was transmitted to HLECs to stabilize the VEGFR3 mRNA and thus formed an hnRNPA1/WNT5A/VEGFR3 feedforward regulatory loop, ultimately promoting the lymphatic metastasis of BCa. Importantly, blocking VEGFR3 with specific inhibitor, SAR131675 significantly impaired exosomal BCYRN1‐induced the LN metastasis in vivo. Clinically, exosomal BCYRN1 was positively associated with the shorter survival of BCa patients and identified as a poor prognostic factor of patients. Conclusion Our results uncover a novel mechanism by which exosomal BCYRN1 synergistically enhances VEGF‐C/VEGFR3 signaling‐induced lymphatic metastasis of BCa, indicating that BCYRN1 may serve as an encouraging therapeutic target for patients with BCa.

Small ubiquitin-like modifier (SUMO) binding (termed SUMOylation) emerged as the inducer for the sorting of bioactive molecules into extracellular vesicles (EVs), triggering lymphangiogenesis and further driving tumor lymph node (LN) metastasis, but the precise mechanisms remain largely unclear. Here, we show that bladder cancer (BCa) cell-secreted EVs mediated intercellular communication with human lymphatic endothelial cells (HLECs) through transmission of the long noncoding RNA ELNAT1 and promoted lymphangiogenesis and LN metastasis in a SUMOylation-dependent manner in both cultured BCa cell lines and mouse models. Mechanistically, ELNAT1 induced UBC9 overexpression to catalyze the SUMOylation of hnRNPA1 at the lysine 113 residue, which mediated recognition of ELNAT1 by the endosomal sorting complex required for transport (ESCRT) and facilitated its packaging into EVs. EV-mediated ELNAT1 was specifically transmitted into HLECs and epigenetically activated SOX18 transcription to induce lymphangiogenesis. Importantly, blocking the SUMOylation of tumor cells by downregulating UBC9 expression markedly reduced lymphatic metastasis in EV-mediated, ELNAT1-treated BCa in vivo. Clinically, EV-mediated ELNAT1 was correlated with LN metastasis and a poor prognosis for patients with BCa. These findings highlight a molecular mechanism whereby the EV-mediated ELNAT1/UBC9/SOX18 regulatory axis promotes lymphangiogenesis and LN metastasis in BCa in a SUMOylation-dependent manner and implicate ELNAT1 as an attractive therapeutic target for LN metastatic BCa. [ABSTRACT FROM AUTHOR]