Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
High Throughput Genome Center, Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
Hepatol Commun. 2024 Jul 31;8(8). doi: 10.1097/HC9.0000000000000511. eCollection 2024 Aug 1.
HCC is one of the most lethal cancers for humans. Mannosidase alpha class 2A member 1 (MAN2A1)-FER is one of the most frequent oncogenic fusion genes in HCC. In this report, we showed that MAN2A1-FER ectopically phosphorylated the extracellular domains of PDGFRA, MET, AXL, and N-cadherin. The ectopic phosphorylation of these transmembrane proteins led to the activation of their kinase activities and initiated the activation cascades of their downstream signaling molecules.
A panel of mouse monoclonal antibodies was developed to recognize the ectopic phosphorylation sites of PDGFRA.
The analyses showed that these antibodies bound to the specific phosphotyrosine epitopes in the extracellular domain of PDGFRA with high affinity and specificity. The treatment of MAN2A1-FER-positive cancer HUH7 with one of the antibodies called 2-3B-G8 led to the deactivation of cell growth signaling pathways and cell growth arrest while having minimal impact on HUH7ko cells where MAN2A1-FER expression was disrupted. The treatment of 2-3B-G8 antibody also led to a large number of cell deaths of MAN2A1-FER-positive cancer cells such as HUH7, HEPG2, SNU449, etc., while the same treatment had no impact on HUH7ko cells. When severe combined immunodeficiency mice xenografted with HEPG2 or HUH7 were treated with monomethyl auristatin E-conjugated 2-3B-G8 antibody, it slowed the progression of tumor growth, eliminated the metastasis, and reduced the mortality, in comparison with the controls. Targeting the cancer-specific ectopic phosphorylation sites of PDGFRA induced by MAN2A1-FER may hold promise as an effective treatment for liver cancer.
肝癌（HCC）是人类最致命的癌症之一。甘露糖苷酶 α 类 2A 成员 1（MAN2A1）-FER 是 HCC 中最常见的致癌融合基因之一。在本报告中，我们表明 MAN2A1-FER 异位磷酸化了 PDGFRA、MET、AXL 和 N-钙黏蛋白的细胞外结构域。这些跨膜蛋白的异位磷酸化导致其激酶活性的激活，并启动了其下游信号分子的激活级联反应。
开发了一组小鼠单克隆抗体来识别 PDGFRA 的异位磷酸化位点。
分析表明，这些抗体以高亲和力和特异性结合 PDGFRA 细胞外结构域中的特异性磷酸酪氨酸表位。用称为 2-3B-G8 的抗体之一处理 MAN2A1-FER 阳性的癌症 HUH7，导致细胞生长信号通路失活和细胞生长停滞，而对 MAN2A1-FER 表达被破坏的 HUH7ko 细胞影响最小。2-3B-G8 抗体的治疗还导致大量 MAN2A1-FER 阳性癌细胞（如 HUH7、HEPG2、SNU449 等）死亡，而相同的治疗对 HUH7ko 细胞没有影响。当严重联合免疫缺陷小鼠异种移植 HEPG2 或 HUH7 并用单甲基奥瑞他汀 E 偶联的 2-3B-G8 抗体治疗时，与对照组相比，它减缓了肿瘤生长的进展，消除了转移，并降低了死亡率。针对 MAN2A1-FER 诱导的癌症特异性异位磷酸化位点可能为肝癌的有效治疗提供希望。
