Purpose: AR-V7 is one of a splicing variant of the Androgen receptor (AR). It cause castration resistant prostate cancer (CRPC).
Incontrast, CTCs is expected as a predictive factor for patients prognosis and as a biomarker of the disease.
CellSearch is the only FDA approval method as an evaluation of CTCs ensuring the quantitative evaluation. This methodology is depending on the expression of EpCAM and CK. However, the decrease expression of EpCAM and CK caused by Epithelial-Mesenchymal Transition (EMT) can be an obstacle to CTC detection.
In recent years, AdnaTest is used for the evaluation of CRPC. It captures CTC depending on EpCAM and Her2 expression on cancer cells, then assess the presence of AR-V7 mRNA. But, this method is semi-quantitative and also depending on expression of EpCAM.
We consider it is important to know the number of ARV-7 positive cells accurately. Because, CTCs of each prostate cancer patients are heterogeneous.
The aim of our study is to establish a new method of improved detection rate of EpCAM and CK-negative cells (i.e EMT cells), ensure the quantitative evaluation and assess the number of AR-V7-positive cells.
Materials and Methods: LNcap was used as hormone sensitive prostate cancer (HSPC) model, and Vcap, PC3 and Du145 were used as CRPC model. Peripheral blood mononuclear cell (PBMC) and VMRC-RCW (Renal cell carcinoma cell) were used as negative control.
CK and EpCAM antibodies were used as CTC-specific antibodies.PSA, PSMA and AR-FL antibody were used as prostate-specific antibodies, cells which show positivitiys for those antiodies within peripheral blood were considered as CTCs.In addition, vimentin antibody was used for the purpose of evaluating the EMT cells.
AR-V7 antibody was used as a biomarker for prostate cancer. On-chip sort was used for quantitative assessment of CTCs.
Conclusion: Negativity of CK-Ab for LNCap and EpCAM-Ab for PC3 may indicate that EMT occurs in LNCap and PC3. Positivity of PSMA-Ab, PSA-Ab and AR-FL-Ab for LNCap indicates the possibility of improving the detection rate of CTC. Positivity of AR-V7-Ab for Vcap and low positivity for LNcap were likely to be the evaluation of new biomarkers in CTC studies.