Epigenetic regulation of the expression of the novel stem cell marker CDCP1 in cancer cells
Department of Pathology, Osaka University Graduate School of Medicine, Yamada-oka 2-2, Suita 565-0871, Japan. The Journal of Pathology
(Impact Factor: 7.43).
09/2006; 210(1):75-84. DOI: 10.1002/path.2026
CDCP1 is a novel stem cell marker that is expressed in several types of cancer. The mechanisms by which CDCP1 expression is regulated, and the clinical implications of this marker, have not been clarified. In this report, we examine the epigenetic regulation of CDCP1 expression in cell lines and clinical samples from patients with breast cancer. Many CpG sequences were localized around the transcription initiation site of CDCP1. These CpG motifs were found to be poorly methylated in cell lines with high levels of CDCP1 expression and heavily methylated in cell lines with low levels of CDCP1 expression. The in vitro methylation of CpG sites decreased CDCP1 promoter activity, and the addition of a demethylating reagent restored activity. In 25 breast cancer samples, an inverse correlation was noted between the CDCP1 expression level and the proportion of methylated to non-methylated CpG sites. Tumours with high-level CDCP1 expression showed higher levels of proliferation, as revealed by immunohistochemical detection of the MIB-1 antigen, than tumours with low-level CDCP1 expression. These findings indicate that the expression of CDCP1 is regulated by methylation of its promoter region in tumours. CDCP1 expression may prove to be useful in the further characterization of cancers.
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- "However, the poor prognosis of cancer patients with high CDCP1 expression levels could also be related to a higher proliferative capacity of their tumors. In a small study with 25 breast cancer patients, Ikeda et al. (2006) found that the CDCP1-high cases also had higher levels of the proliferation-associated Ki67 antigen than the CDCP1-low cases. CDCP1 consists of a large extracellular domain (ECD), which contains three CUB (Complement C1r/C1s, Uegf, Bmp1) domains, and a short intracellular portion (Scherl- Mostageer et al., 2001). "
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ABSTRACT: CUB-domain-containing-protein-1 (CDCP1) is an integral membrane protein whose expression is up-regulated in various cancer types. Although high CDCP1 expression has been correlated with poor prognosis in lung, breast, pancreas, and renal cancer, its functional role in tumor formation or progression is incompletely understood. So far it has remained unclear, whether CDCP1 is a useful target for antibody therapy of cancer and what could be a desired mode of action for a therapeutically useful antibody. To shed light on these questions, we have investigated the cellular effects of a therapeutic antibody candidate (RG7287). In focus formation assays, prolonged RG7287 treatment prevented the loss of contact inhibition caused by co-transformation of NIH3T3 cells with CDCP1 and Src. In a xenograft study, MCF7 cells stably overexpressing CDCP1 reached the predefined tumor volume faster than the parental MCF7 cells lacking endogenous CDCP1. This tumor growth advantage was abolished by RG7287 treatment. In vitro, RG7287 induced rapid tyrosine phosphorylation of CDCP1 by Src, which was accompanied by translocation of CDCP1 to a Triton X-100 insoluble fraction of the plasma membrane. Triggering these effects required bivalency of the antibody suggesting that it involves CDCP1 dimerization or clustering. However, this initial activation of CDCP1 was only transient and prolonged RG7287 treatment induced internalization and down-regulation of CDCP1 in different cancer cell lines. Antibody stimulated CDCP1 degradation required Src activity and was proteasome dependent. Also in three different xenograft models with endogenous CDCP1 expression RG7287 treatment resulted in significant tumor growth inhibition concomitant with substantially reduced CDCP1 levels as judged by immunohistochemistry and Western blotting. Thus, despite transiently activating CDCP1 signaling, the RG7287 antibody has a therapeutically useful mode of action.
Available from: Yuyu Yao
- "DNA methylation is an important mechanism for gene transcriptional silencing. CpG hypermethylation in DNA promoter regions is responsible for gene silencing –. DNA methylation status was regulated by DNMT, which has de novo methylation activity. "
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ABSTRACT: Cardiac progenitor cells (CPCs) have been proven suitable for stem cell therapy after myocardial infarction, especially c-kit(+)CPCs. CPCs marker c-kit and its ligand, the stem cell factor (SCF), are linked as c-kit/SCF axis, which is associated with the functions of proliferation and differentiation. In our previous study, we found that stromal cell-derived factor-1α (SDF-1α) could enhance the expression of c-kit. However, the mechanism is unknown.
CPCs were isolated from adult mouse hearts, c-kit(+) and c-kit(-) CPCs were separated by magnetic beads. The cells were cultured with SDF-1α and CXCR4-selective antagonist AMD3100, and c-kit expression was measured by qPCR and Western blotting. Results showed that SDF-1α could enhance c-kit expression of c-kit(+)CPCs, made c-kit(-)CPCs expressing c-kit, and AMD3100 could inhibit the function of SDF-1α. After the intervention of SDF-1α and AMD3100, proliferation and migration of CPCs were measured by CCK-8 and transwell assay. Results showed that SDF-1α could enhance the proliferation and migration of both c-kit(+) and c-kit(-) CPCs, and AMD3100 could inhibit these functions. DNA methyltransferase (DNMT) mRNA were measured by qPCR, DNMT activity was measured using the DNMT activity assay kit, and DNA methylation was analyzed using Sequenom's MassARRAY platform, after the CPCs were cultured with SDF-1α. The results showed that SDF-1α stimulation inhibited the expression of DNMT1 and DNMT3β, which are critical for the maintenance of regional DNA methylation. Global DNMT activity was also inhibited by SDF-1α. Lastly, SDF-1α treatment led to significant demethylation in both c-kit(+) and c-kit(-) CPCs.
SDF-1α combined with CXCR4 could up-regulate c-kit expression of c-kit(+)CPCs and make c-kit(-)CPCs expressing c-kit, which result in the CPCs proliferation and migration ability improvement, through the inhibition of DNMT1 and DNMT3β expression and global DNMT activity, as well as the subsequent demethylation of the c-kit gene.
Available from: Minyoung Lee
- "CDCP1 gene regulation has been investigated in various cancer cell lines. PC3 cells show abundant expression of CDCP1 protein and a low frequency of methylation in transcription-initiation sites . We found that both HMW and LMW forms of CDCP1 are expressed in PC3 cells (Figure 2). "
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ABSTRACT: KAI1 was initially identified as a metastasis-suppressor gene in prostate cancer. It is a member of the tetraspan transmembrane superfamily (TM4SF) of membrane glycoproteins. As part of a tetraspanin-enriched microdomain (TEM), KAI1 inhibits tumor metastasis by negative regulation of Src. However, the underlying regulatory mechanism has not yet been fully elucidated. CUB-domain-containing protein 1 (CDCP1), which was previously known as tetraspanin-interacting protein in TEM, promoted metastasis via enhancement of Src activity. To better understand how KAI1 is involved in the negative regulation of Src, we here examined the function of KAI1 in CDCP1-mediated Src kinase activation and the consequences of this process, focusing on HIF-1 α and VEGF expression.
We used the human prostate cancer cell line PC3 which was devoid of KAI1 expression. Vector-transfected cells (PC3-GFP clone #8) and KAI1-expressing PC3 clones (PC3-KAI1 clone #5 and #6) were picked after stable transfection with KAI1 cDNA and selection in 800 μg/ml G418. Protein levels were assessed by immunoblotting and VEGF reporter gene activity was measured by assaying luciferase activitiy. We followed tumor growth in vivo and immunohistochemistry was performed for detection of HIF-1, CDCP1, and VHL protein level.
We demonstrated that Hypoxia-inducible factor 1α (HIF-1α) and VEGF expression were significantly inhibited by restoration of KAI1 in PC3 cells. In response to KAI1 expression, CDCP1-enhanced Src activation was down-regulated and the level of von Hippel-Lindau (VHL) protein was significantly increased. In an in vivo xenograft model, KAI1 inhibited the expression of CDCP1 and HIF-1α.
These novel observations may indicate that KAI1 exerts profound metastasis-suppressor activity in the tumor malignancy process via inhibition of CDCP1-mediated Src activation, followed by VHL-induced HIF-1α degradation and, ultimately, decreased VEGF expression.
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