Finsen Laboratory, Rigshospitalet/Biotech Research & Innovation Centre (BRIC), University of Copenhagen, 2200 Copenhagen, Denmark.
Department of Pathology, Rigshospitalet, University of Copenhagen, 2100 Copenhagen, Denmark.
Int J Mol Sci. 2021 Oct 23;22(21):11452. doi: 10.3390/ijms222111452.
Malignant mesothelioma (MM) is a highly aggressive cancer with limited therapeutic options. We have previously shown that the endocytic collagen receptor, uPARAP, is upregulated in certain cancers and can be therapeutically targeted. Public RNA expression data display uPARAP overexpression in MM. Thus, to evaluate its potential use in diagnostics and therapy, we quantified uPARAP expression by immunohistochemical H-score in formalin-fixed paraffin-embedded bioptic/surgical human tissue samples and tissue microarrays. We detected pronounced upregulation of uPARAP in the three main MM subtypes compared to non-malignant reactive mesothelial proliferations, with higher expression in sarcomatoid and biphasic than in epithelioid MM. The upregulation appeared to be independent of patients' asbestos exposure and unaffected after chemotherapy. Using immunoblotting, we demonstrated high expression of uPARAP in MM cell lines and no expression in a non-malignant mesothelial cell line. Moreover, we showed the specific internalization of an anti-uPARAP monoclonal antibody by the MM cell lines using flow cytometry-based assays and confocal microscopy. Finally, we demonstrated the sensitivity of these cells towards sub-nanomolar concentrations of an antibody-drug conjugate formed with the uPARAP-directed antibody and a potent cytotoxin that led to efficient, uPARAP-specific eradication of the MM cells. Further studies on patient cohorts and functional preclinical models will fully reveal whether uPARAP could be exploited in diagnostics and therapeutic targeting of MM.
恶性间皮瘤（MM）是一种侵袭性很强的癌症，治疗选择有限。我们之前已经表明，内吞胶原受体 uPARAP 在某些癌症中上调，并且可以作为治疗靶点。公共 RNA 表达数据显示 MM 中存在 uPARAP 的过表达。因此，为了评估其在诊断和治疗中的潜在用途，我们通过免疫组织化学 H 评分法对福尔马林固定石蜡包埋的活检/手术人类组织样本和组织微阵列中的 uPARAP 表达进行了定量。与非恶性反应性间皮增生相比，我们在三种主要的 MM 亚型中检测到 uPARAP 的明显上调，肉瘤样和双相 MM 中的表达高于上皮样 MM。这种上调似乎独立于患者的石棉暴露，并且在化疗后不受影响。通过免疫印迹，我们在 MM 细胞系中证明了 uPARAP 的高表达，而在非恶性间皮细胞系中没有表达。此外，我们使用基于流式细胞术的测定法和共聚焦显微镜显示了 MM 细胞系对靶向 uPARAP 的单克隆抗体的特异性内化。最后，我们证明了这些细胞对与 uPARAP 定向抗体和有效细胞毒素形成的抗体药物偶联物的亚纳摩尔浓度的敏感性，导致 MM 细胞的有效、uPARAP 特异性消除。对患者队列和功能临床前模型的进一步研究将充分揭示 uPARAP 是否可用于 MM 的诊断和治疗靶向。
