Construction and Clinical Verification of Cytoplasm Protein GFAP as Circulating Tumor Cell Separation target for Pediatric Neuroepithelial Tumors

BACKGROUND: Pediatric Neuroepithelial Tumors (NT) are one of the most prevalent diseases among children. Developing a highly efficient cerebrospinal fluid (CSF) detection system with diagnosis and prediction function is very important. Circulating tumor cell (CTC) in CSF is a good choice. In contrast to the past use of epithelial EpCAM as CTC separation target, an cytoplasm protein of GFAP antibody was first selected to construct highly-sensitive immunomagnetic liposomes (IMLs). The validation and efficiency of this system in capturing CTCs for NT were measured both in vitro and in vivo. The associations between the numbers of CTCs in patients with their clinical characteristics were further analyzed. RESULTS: Our data show that CTCs can be successfully isolated from CSF and blood samples from 29 children with NT. The numbers of CTCs in CSF were significantly higher than those in blood. The level of CTCs in CSF was related to the type and location of the tumor rather than its stage. Genetic testing in GFAP CTC-DNA by sanger sequencing, q-PCR and NGS methods indicated that the isolated CTCs (GFAP+/EGFR+) are the related tumor cell. For example, the high expression of NPR3 gene in CSF CTC was consistant with tumor tissue. CONCLUSIONS: GFAP-IML isolation of CTCs, combined with an EGFR immunofluorescence assay of antitumor marker, can serve as a brand-new method for the identification of CTCs for brain tumors. Via lumbar puncture, a minimally invasive procedure, this technique can be clinically significant in diagnosis and efficacy assessments of pediatric NT.