title: Detection of circulating tumor cell-specific markers in breast cancer patients using the quantitative RT-PCR assay.
abstract: BACKGROUND
  Breast cancer is a highly prevalent disease among women worldwide. While the expression of certain proteins within breast cancer tumors is used to determine the prognosis and select therapies, additional markers need to be identified. Circulating tumor cells (CTCs) are constituent cells that have detached from a primary tumor to circulate in the bloodstream. CTCs are considered the main source of breast cancer metastases; therefore, detection of CTCs could be a promising diagnostic method for metastatic breast cancer.
  
  
  METHODS
  In this study, the CircleGen CTC RT-qDx assay was used to analyze the mRNA expression levels of six CTC-specific markers including EpCAM, CK19, HER2, Ki67, hTERT, and vimentin with a total of 692 peripheral whole blood samples from 221 breast cancer patients and 376 healthy individuals.
  
  
  RESULTS
  This assay showed high specificity with multiple markers; none of the healthy controls were detected positive, whereas 21.7 and 14 % of breast cancer patients were positive for EpCAM and CK19, respectively. Of the 221 breast cancer patients, 84 (38 %), 46 (20.8 %), 83 (37.6 %), and 39 (17.6 %) were positively for HER2, Ki67, hTERT, and vimentin mRNA, respectively. Of the 84 patients who were HER2 positive, nine (4 %) were also positive for EpCAM, CK19, Ki67, hTERT, and vimentin. Of the 139 breast cancer patients who were HER2 negative, 65 (29.1 %) were negative for EpCAM, CK19, Ki67, hTERT, and vimentin. Furthermore, the EpCAM-positive population decreased from 21.5 to 8.3 % after completion of anti-tumor treatment (TP4). Similarly, the CK19, HER2, hTERT, and vimentin positives also decreased from 13.9 to 9.5 %, from 37.7 to 21.4 %, from 37.2 to 33.3 %, and from 17.5 to 14.3 %, respectively, after completion of anti-tumor treatment. In contrast, the Ki67 positives increased from 20.6 to 41.7 % after completion of anti-tumor treatment.
  
  
  CONCLUSIONS
  mRNA overexpression of six CTC-specific markers was detected by the CircleGen CTC RT-qDx assay with high specificity, and the obtained mRNA expression levels of CTC-specific markers might provide useful criteria to select appropriate anti-tumor treatment for breast cancer patients.
authors.affiliation: M&D, Inc., Wonju Eco Environmental Technology Center, Wonju, Gangwon, Republic of Korea.
authors.forename: Hye-Young
authors.initials: HY
authors.lastname: Wang
authors.affiliation: Department of Biomedical Laboratory Science, College of Health Sciences, Yonsei University, 1 Yonseidae-gil, Wonju, Gangwon, 220-710, Republic of Korea.
authors.forename: Sungwoo
authors.initials: S
authors.lastname: Ahn
authors.affiliation: Department of Biomedical Laboratory Science, College of Health Sciences, Yonsei University, 1 Yonseidae-gil, Wonju, Gangwon, 220-710, Republic of Korea.|Institute for Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea.
authors.forename: Sunghyun
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Biomedical Laboratory Science, College of Health Sciences, Yonsei University, 1 Yonseidae-gil, Wonju, Gangwon, 220-710, Republic of Korea.
authors.forename: Sunyoung
authors.initials: S
authors.lastname: Park
authors.affiliation: Department of Biomedical Laboratory Science, College of Natural Sciences, Hoseo University, Chungnam, Republic of Korea.
authors.forename: Dongju
authors.initials: D
authors.lastname: Jung
authors.affiliation: Department of Clinical Laboratory Science, College of Medical Science, Daegu Haany University, Daegu, Republic of Korea.
authors.forename: Sangjung
authors.initials: S
authors.lastname: Park
authors.affiliation: Avison Biomedical Research Center, Yonsei University Medical Center, Seoul, Republic of Korea.
authors.forename: Hyunju
authors.initials: H
authors.lastname: Han
authors.affiliation: Division of Medical Oncology, Severance Breast Cancer Clinic, Yonsei Cancer Center, Seoul, Republic of Korea.
authors.forename: JooHyuk
authors.initials: J
authors.lastname: Sohn
authors.affiliation: Department of Surgery, Yonsei University College of Medicine, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 120-752, Republic of Korea. skim@yuhs.ac.
authors.forename: SeungIl
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Biomedical Laboratory Science, College of Health Sciences, Yonsei University, 1 Yonseidae-gil, Wonju, Gangwon, 220-710, Republic of Korea. hyelee@yonsei.ac.kr.
authors.forename: Hyeyoung
authors.initials: H
authors.lastname: Lee
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D001943:Breast Neoplasms / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009360:Neoplastic Cells, Circulating / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor
keywords: Anti-tumor treatment; Breast cancer; Circulating tumor cells (CTCs); Molecular diagnosis; RT-qPCR