Abstract LB-357: HIF-dependent over-expression of CUB domain-containing protein 1 stimulates migration in clear cell renal cell carcinoma

Abstract

Abstract Kidney cancer is the sixth leading cause of cancer death in the USA, and the primary tumor is frequently accompanied by metastasis to lungs, liver, brain and bones. Importantly a large number of kidney cancer cases are characterized by loss of von Hippel-Lindau (VHL) gene, which leads to stabilization of hypoxia-inducible factors (HIFs), which contribute to tumor progression and metastasis by multiple mechanisms. CUB-domain-containing protein 1 (CDCP1) was shown to be expressed on the cell surface of metastatic cell lines and to increase the number of nodules formed by lung adenocarcinoma cells and melanoma in lungs in tail vein injection experiments, enhance peritoneal dissemination of scirrhous adenocarcinoma, and to induce metastasis in the chicken embryo metastatic model. In the present study we investigated the role of CDCP1 protein in clear cell renal cell carcinoma (CC-RCC) and found it to be upregulated in this disease entity by a mechanism of VHL loss through HIFs. Interestingly, we found CDCP1 protein expressed not only on the membrane of kidney cancer cell lines, but also to be secreted into the media as a full length isoform. Importantly, in the knockdown experiments we found CDCP1 to promote CC-RCC cell migration in vitro, the process known to be the key during metastasis. Accordingly CDCP1 participates in the signal transduction pathway leading to PKCδ phosphorylation in CC-RCC, stimulating migration. The role of PKCδ in CDCP1-dependent migration was verified by the PKCδ knockdown experiments, which phenocopy the effect of CDCP1 knockdown; as well as migration rescue experiments, where the impairment of migration caused by CDCP1 downregulation was rescued by the overexpression of constitutively active mutant of PKCδ. Furthermore, we showed a correlation of CDCP1 cell surface expression in primary tumor with poor patient outcome. Finally, we found that suramin, a drug, which showed the clinical benefit for CC-RCC patients at premetastatic stages, causes the downregulation of CDCP1 at the protein level. Thus, the further investigation of the role of CDCP1 protein in kidney cancer metastasis is important to validate CDCP1 as a therapeutic target. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-357. doi:10.1158/1538-7445.AM2011-LB-357