Intrahepatic cholangiocarcinoma (ICC) is a primary epithelial carcinoma known for its aggressive nature, high metastatic potential, frequent recurrence, and poor prognosis. Heparanase (HPSE) is the only known endogenous β-glucuronidase in mammals. In addition to its well-established enzymatic roles, HPSE critically exerts non-catalytic function in tumor biology. This study herein aimed to investigate the non-enzymatic roles of HPSE as well as relevant regulatory mechanisms in ICC. Our results demonstrated that HPSE was highly expressed in ICC and promoted the proliferation of ICC cells, with elevated HPSE levels implicating a poor overall survival of ICC patients. Notably, HPSE interacted with Bcl-2-associated factor 1 (BCLAF1) to upregulate the expression of Bcl-2, which subsequently activated the PERK/eIF2α-mediated endoplasmic reticulum (ER) stress pathway to promote anti-apoptotic effect of ICC. Moreover, our in vivo experiments revealed that concomitant administration of gemcitabine and the Bcl-2 inhibitor navitoclax enhanced the sensitivity of ICC cells with highly expressed HPSE to chemotherapy. In summary, our findings revealed that HPSE promoted the development and drug resistance of ICC via its non-enzymatic function. Bcl-2 may be considered as an effective target with therapeutic potential to overcome ICC chemotherapy resistance induced by HPSE, presenting valuable insights into the development of novel therapeutic strategies against ICC.

肝内胆管癌（ICC）是一种原发性上皮癌，以其侵袭性、高转移潜力、频繁复发和预后不良而闻名。乙酰肝素酶（HPSE）是哺乳动物中唯一已知的内源性β-葡萄糖醛酸酶。除了其公认的酶作用外，HPSE 在肿瘤生物学中发挥着重要的非催化功能。本研究旨在探讨 HPSE 在 ICC 中的非酶作用以及相关调控机制。我们的结果表明，HPSE 在 ICC 中高表达并促进 ICC 细胞的增殖，HPSE 水平升高意味着 ICC 患者的总体生存率较差。值得注意的是，HPSE与Bcl-2相关因子1（BCLAF1）相互作用，上调Bcl-2的表达，随后激活PERK/eIF2α介导的内质网（ER）应激通路，促进ICC的抗凋亡作用。此外，我们的体内实验表明，同时给予吉西他滨和 Bcl-2 抑制剂 navitoclax 可以增强高表达 HPSE 的 ICC 细胞对化疗的敏感性。总之，我们的研究结果表明，HPSE 通过其非酶功能促进 ICC 的发展和耐药性。Bcl-2可能被认为是具有克服HPSE诱导的ICC化疗耐药性的治疗潜力的有效靶点，为针对ICC的新型治疗策略的开发提供了宝贵的见解。