Bartkowiak Kai, Mohammadi Parinaz Mossahebi, Nissen Paula, Werner Stefan, Agorku David, Andreas Antje, Geffken Maria, Peine Sven, Verpoort Karl, Deutsch Thomas M, Michel Laura L, Schneeweiss Andreas, Thewes Verena, Trumpp Andreas, Hardt Olaf, Müller Volkmar, Riethdorf Sabine, Schlüter Hartmut, Pantel Klaus
Department for Tumour Biology, University Medical Centre Hamburg-Eppendorf, Martinistraße 52, 20246, Hamburg, Germany.
Section Mass Spectrometry and Proteomics, University Medical Centre Hamburg-Eppendorf, Martinistraße 52, 20246, Hamburg, Germany.
Sci Rep. 2025 Jan 31;15(1):3913. doi: 10.1038/s41598-025-87122-4.
Cell lines derived from circulating tumor cells (CTCs) in the blood provide important biological information on cancer metastasis. CTC-ITB-01 is a CTC cell line derived from a patient with metastatic estrogen receptor-alpha (ER-alpha) positive breast cancer two months before the death of the patient. After a LC-MC/MS based proteomics analysis of CTC-ITB-01, we found extraordinary high levels of the poorly characterized protein SUSD2 (sushi domain-containing protein 2) in CTC-ITB-01. Expression of SUSD2 on subsets of CTCs was validated on clinical blood samples of patients with metastatic breast cancer. SUSD2-positive CTCs could be captured specifically by a MACS-based approach. We overexpressed SUSD2 in the poorly-metastatic cell line MCF-7. This resulted in upregulation of ER-alpha, the tumor progression protein GRP78 (78-kDa glucose-regulated protein) and downregulation of the tumor suppressor protein PDCD4 (programmed cell death protein 4). We observed downregulation of SUSD2 and PDCD4 after hypoxia and simulation of re-oxygenation in the blood in MCF-7 and MDA-MB-468, while in CTC-ITB-01 SUSD2 levels remained unchanged, and only PDCD4 was downregulated under hypoxia. In conclusion, we show, for the first time, that SUSD2 is expressed in CTCs and appears to affect key proteins in tumor progression and survival.
源自血液中循环肿瘤细胞（CTC）的细胞系为癌症转移提供了重要的生物学信息。CTC-ITB-01是一种源自一名转移性雌激素受体α（ER-α）阳性乳腺癌患者的CTC细胞系，该患者在去世前两个月建立。对CTC-ITB-01进行基于液相色谱-质谱联用（LC-MC/MS）的蛋白质组学分析后，我们发现CTC-ITB-01中一种特征不明的蛋白质SUSD2（含寿司结构域蛋白2）水平异常高。在转移性乳腺癌患者的临床血液样本中验证了SUSD2在部分CTC上的表达。基于磁珠分选（MACS）的方法可以特异性捕获SUSD2阳性的CTC。我们在低转移细胞系MCF-7中过表达SUSD2。这导致ER-α、肿瘤进展蛋白GRP78（78 kDa葡萄糖调节蛋白）上调，肿瘤抑制蛋白PDCD4（程序性细胞死亡蛋白4）下调。在MCF-7和MDA-MB-468细胞中，缺氧和模拟血液再氧合后，我们观察到SUSD2和PDCD4下调，而在CTC-ITB-01中，SUSD2水平保持不变，仅在缺氧条件下PDCD4下调。总之，我们首次表明SUSD2在CTC中表达，并且似乎影响肿瘤进展和生存中的关键蛋白。
