Dysregulated expression of cell surface glycoprotein CDCP1 in prostate cancer

Abstract

CUB-domain-containing protein 1 (CDCP1) is a trans-membrane protein regulator of cell adhesion with a potent pro-migratory function in tumors. Given that proteolytic cleavage of the ectodomain correlates with outside-in oncogenic signaling, we characterized glycosylation in the context of cellular processing and expression of CDCP1 in prostate cancer. We detected 135 kDa full-length and proteolytic processed 70 kDa species in a panel of PCa cell models. The relative expression of full-length CDCP1 correlated with the metastatic potential of syngeneic cell models and an increase in surface membrane expression of CDCP1 was observed in tumor compared to adjacent normal prostate tissues. We demonstrated that glycosylation of CDCP1 is a prerequisite for protein stability and plasma membrane localization, and that the expression level and extent of N-glycosylation of CDCP1 correlated with metastatic status. Interestingly, complex N-linked glycans with sialic acid chains were restricted to the N-terminal half of the ectodomain and absent in the truncated species. Characterization of the extracellular expression of CDCP1 identified novel circulating forms and revealed that extracellular vesicles provide additional processing pathways. Employing immunoaffinity mass spectrometry, we detected elevated levels of circulating CDCP1 in patient urine with high-risk disease. Our results establish that differential glycosylation, cell surface presentation and extracellular expression of CDCP1 are hallmarks of PCa progression.

CDCP1 overexpression drives prostate cancer progression and can be targeted in vivo

“…In prostate cancer, the role of CDCP1 remains poorly characterized due to the lack of an in vivo model. Previous reports demonstrate that CDCP1 overexpression increases cellular proliferation in 2 human prostate cancer cell lines with validation of its elevated expression in a limited number of primary prostate tumor samples (28,53). In an attempt to clarify the function of CDCP1 in prostate cancer, we generated the first prostate-specific CDCP1-overexpressing transgenic mouse model and assessed the level of CDCP1 in different prostate cancer TMAs, including more than 990 cases spanning benign, primary, and metastatic prostate cancer.…”

Extracellular vesicles for liquid biopsy in prostate cancer: where are we and where are we headed?

“… 55 , 56 CDCP1 was also detected in EVs from invasive PC cells with characteristics of epithelial to mesenchymal transition 57 but not from isogenic, less aggressive cells. 58 Additionally, identification of CDCP1 in urine samples by an antibody specific to the ectodomain of the protein discriminated patients with high-risk versus low-risk PC. 58 These results demonstrate that cell-surface proteins can be used to identify tumor-derived EVs and support the use of CDCP1-positive EVs as circulating markers of PC.…”

Development of an enzyme-linked immunosorbent assay for detection of CDCP1 shed from the cell surface and present in colorectal cancer serum specimens

“…We have shown for the first time that the level of ShE-CDCP1 is significantly higher in serum of colorectal cancer patients compared with the serum of individuals with benign conditions, and that elevated levels may be indicative of cancer that has spread beyond the colonic mucosa. The use of anti-ShE-CDCP1 ELISAs may potentially be extended to other malignancies as CDCP1 is cleaved in a wide range of cancer cell lines [3,20], fragments of CDCP1 are present in the urine of prostate cancer patients at high risk of poor survival [21], and CDCP1 cleavage is necessary for triple negative breast cancer migration [23] and for vascular metastasis in animal models [15,16]. ) and (C) are mean ± SEM, aggregated from data from three assays that each included duplicate wells.…”

“…As summarized in Figure 1A, the ECD of CDCP1 spans residue 30 to 666, and is shed from the surface of cultured cell lines by cleavage at R368 and K369, generating fragments of about 65 kDa, designated ShE-CDCP1, that are stable in conditioned media [20] and present in urine of prostate cancer patients [21]. CDCP1 cleavage is apparent in a wide range of cancer cell lines including those derived from colorectal tumors [3].…”

“…These are designated ShE-CDCP1 368 and ShE-CDCP1 369 (collectively termed ShE-CDCP1) and differ by a single carboxylterminal amino acid [20]. Western blot analysis has revealed elevated levels of ShE-CDCP1 in the urine of prostate cancer patients at high risk of poor survival [21], and in conditioned media of prostate cancer cell lines [20]. Also, there is indirect evidence from Western blot analyses of tissue lysates, that CDCP1 cleavage occurs in high grade serous ovarian carcinoma patients [22], and in many cell lines derived from epithelial tumors [3,20].…”