目的 探讨在淋巴转移阳性膀胱癌组织中高表达的环状RNA（circular RNA， circRNA）MYCBP2在增强膀胱癌细胞黏附能力介导淋巴管癌栓形成中的作用机制，评估其临床相关性及潜在应用价值。 方法 首先通过高通量测序筛选出在淋巴转移阳性膀胱癌组织中高表达的circRNA，并进一步通过扩大临床样本验证其在膀胱癌组织中的表达情况。通过circBank生物信息网站预测其编码能力，免疫共沉淀结合银染实验及蛋白质印迹（Western blot， WB）检测编码短肽。通过RNA pulldown、实时荧光定量PCR（qRT-PCR）和WB实验探究circMYCBP2与真核翻译起始因子3亚基H（eukaryotic translation initiation factor 3 subunit H， EIF3H）相互作用介导翻译及调控血管细胞黏附分子1（vascular cell adhesion molecule 1， VCAM-1）的转录，进而促进脉管癌栓形成的分子机制。接着通过在体外构建过表达和敲低circMYCBP2的膀胱癌细胞，结合跨内皮细胞迁移实验和划痕实验验证circMYCBP2编码的短肽对膀胱癌细胞侵袭能力的影响。 结果 高通量测序和临床大样本实验分析证实circMYCBP2在淋巴转移阳性的膀胱癌组织中高表达。体外实验证实过表达circMYCBP2能显著促进膀胱癌细胞跨越淋巴管内皮细胞。机制上，circMYCBP2通过IRES依赖机制结合EIF3H编码MYCBP2-227aa，过表达MYCBP2-227aa后VCAM-1的信使RNA（message RNA，mRNA）稳定性增加，进而增强UM-UC-3细胞侵袭能力。 结论 circMYCBP2通过EIF3H介导的IRES依赖翻译机制编码短肽MYCBP2-227aa，该短肽的表达影响VCAM-1的表达水平和膀胱癌细胞的侵袭能力。充分阐述了circMYCBP2在淋巴管癌栓形成及淋巴转移中发挥的重要生物学作用及其分子机制，为膀胱癌的早期淋巴转移靶向治疗提供了潜在生物标志物及干预靶点。

Objective To investigate the role of circular RNA， circMYCBP2， which is highly expressed in lymph node （LN） metastatic bladder cancer （BCa） tissues， in enhancing BCa cell adhesion and mediating lymphovascular invasion （LVI）， and to evaluate its clinical relevance and potential therapeutic value. Methods High-throughput sequencing identified circRNAs with high expression in LN metastatic BCa tissues. Further validation of their expression in bladder cancer tissues was conducted through clinical samples. The coding ability of circMYCBP2 was predicted by circBank bioinformatics website， and the encoded short peptide was detected by immunoprecipitation（co-IP）combined with silver staining and Western blot （WB）. Then， by constructing BCa cells with overexpression and knockdown of circMYCBP2 in vitro，the invasive ability of BCa cells was verified by wound healing and transendothelial cell migration assays. The underlying mechanism of circMYCBP2 in the formation of LVI was explored through RNA pulldown， qRT-PCR and WB. Results High-throughput sequencing and clinical sample validation confirmed that circMYCBP2 is highly expressed in LN metastatic BCa.In vitro experiments demonstrated that circMYCBP2 overexpression significantly enhanced BCa cell migration across lymphatic endothelial cells. Mechanistically，circMYCBP2 encodes the short peptide MYCBP2-227aa via an IRES-dependent mechanism by interacting with EIF3H.Overexpression of MYCBP2-227aa increased the mRNA stability of VCAM-1， thereby enhancing the invasive capacity of UM-UC-3 cells. Conclusions CircMYCBP2 encodes the short peptide MYCBP2-227aa through an EIF3H-mediated， IRES-dependent translation mechanism.MYCBP2-227aa regulates VCAM-1 expression and promotes the invasive behavior of BCa cells. Our findings elucidate the critical biological role and molecular mechanism of circMYCBP2 in the formation of LVI and LN metastasis of BCa， providing a potential biomarker and therapeutic target for early lymphatic metastasis in BCa.