Gene Expression Analysis of Immunomagnetically Enriched Circulating Tumor Cell Fraction in Castration-Resistant Prostate Cancer
- 91 Downloads
Molecular characterization of tumors could be a key to therapeutic decision-making with regards to targeted therapies in castration-resistant prostate cancer (CRPC). A convenient solution may be non-invasive liquid biopsy testing of circulating tumor cells (CTCs). For this reason, CTC-enriched samples obtained by immunomagnetic separation (AdnaTest®) were studied as a source material for high-throughput gene expression analysis using BioMark™.
Patients and Methods
CTC-enriched samples from 41 CRPC patients previously determined to be CTC positive using the AdnaTest® were retrospectively re-analysed for androgen receptor (AR) messenger RNA (mRNA), using the updated AdnaTest®. Blood samples were drawn two times from each patient: at the time of CRPC diagnosis and after the third docetaxel cycle. A gene expression panel of 27 genes related to CRPC therapeutic decision-making, including AR full length (ARFL) and splice variant 7 (ARV7), was retrospectively analyzed on a BioMark™ platform in 29 of 41 patients.
The AdnaTest® detected AR mRNA in three-quarters of CTC-positive samples taken at the time of CRPC diagnosis and after the third docetaxel cycle. AR detection was associated with a shorter disease-specific survival (45.0 vs. 20.4 months) at the time of CRPC diagnosis. ARFL expression at the time of CRPC diagnosis, measured on the BioMark™ platform, was associated with a lower decrease of serum level of prostate-specific antigen (sPSA) (p = 0.029), i.e., worse therapy response. ARV7 was found in 38% of the ARFL–-positive samples at both analyzed timepoints.
Detection of AR expression by AdnaTest® in CTC-enriched samples may help predict patients’ survival. These AdnaTest® CTC-enriched samples can be used in a high-throughput quantitative polymerase chain reaction (qPCR) analysis of gene expression, provided that the specificity of the assay for each individual gene is properly validated. The BioMark™ platform can be used for the simultaneous detection of ARFL and ARV7 and other genes in CTC-enriched samples from CRPC patients.
We would like to thank our collaborators from the Laboratory of Gene Expression, Institute of Biotechnology, Czech Academy of Sciences (CAS) for their help with qPCR measurement and data analysis and Ing. Stanislav Kormunda for his help with the statistical evaluation of the results.
Compliance with Ethical Standards
This work was supported by the Ministry of Health, Czech Republic, IGA NT 12205-5/201; institutional support of the General University Hospital RVO VFN 64165 and Progres Q25/LF1; research support of the First Faculty of Medicine SVV 260 263; BIOCEV CZ.1.05/1.1.00/02.0109 from the European Regional Development Fund (ERDF); and LQ1604 NPU II provided by Ministry of Education, Youth and Sports (MEYS).
Conflict of interest
Markéta Škereňová, Veronika Mikulová, Otakar Čapoun, David Švec, Katarína Kološtová, Viktor Soukup, Hana Honová, Tomáš Hanuš, and Tomáš Zima state that they have no conflicts of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
- 2.Bahl A, Oudard S, Tombal B, Ozgüroglu M, Hansen S, Kocak I, et al. Impact of cabazitaxel on 2-year survival and palliation of tumour-related pain in men with metastatic castration-resistant prostate cancer treated in the TROPIC trial. Ann Oncol. 2013;24:2402–8.CrossRefPubMedPubMedCentralGoogle Scholar
- 18.Vandesompele J, De Preter K, Pattyn F, Poppe B, Van Roy N, De Paepe A, et al. Accurate normalization of realtime quantitative RT-PCR data by geometric averaging of multiple internal control genes. Genome Biol. 2002;3(7):RESEARCH0034Google Scholar
- 19.Andersen CL, Jensen JL, Ørntoft TF. Normalization of real-time quantitative reverse transcription-PCR data: a model-based variance estimation approach to identify genes suited for normalization, applied to bladder and colon cancer data sets. Cancer Res. 2004;64(15):5245–50.CrossRefPubMedGoogle Scholar
- 26.Dijkstra S, Leyten GHJM, Jannink SA, de Jong H, Mulders PFA, van Oort IM, et al. KLK3, PCA3, and TMPRSS2-ERG expression in the peripheral blood mononuclear cell fraction from castration-resistant prostate cancer patients and response to docetaxel treatment. Prostate. 2014;74:1222–30.CrossRefPubMedGoogle Scholar