Poster Presentation 35th Lorne Cancer Conference 2023

Choice of antibody is critical for specific and sensitive detection of androgen receptor splice variant-7 in circulating tumour cells (#209)

Tanzila Khan 1 2 3 4 , Yafeng Ma 1 2 3 4 , John Lock 2 5 , David G. Harman 6 , Paul de Souza 1 2 3 , Wei Chua 1 3 4 7 , Bavanthi Balakrishnar 7 , Kieran F. Scott 1 3 , Therese M. Becker 1 2 3 4
  1. School of Medicine, Western Sydney University, Liverpool, NSW, Australia
  2. Centre of Circulating Tumour Cells Diagnostics and Research, Ingham Institute for Applied Medical Research, Liverpool, NSW, Australia
  3. Medical Oncology, Ingham Institute for Applied Medical Research, Liverpool, NSW, Australia
  4. South Western Sydney Clinical School, University of New South Wales, Liverpool, NSW, Australia
  5. School of Medical Sciences, University of New South Wales, Sydeny, NSW, Australia
  6. School of Science, Western Sydney University, Campbelltown, NSW, Australia
  7. Medical Oncology, Liverpool Hospital, Liverpool, NSW, Australia

Androgen receptor variant 7 (AR-V7) is an important biomarker to guide treatment options for castration-resistant prostate cancer (CRPC) patients. Its detectability in circulating tumour cells (CTCs) opens non-invasive diagnostic avenues. While detectable at the transcript level, AR-V7 protein detection in CTCs may add additional information and clinical relevance. The aim of this study was to compare commercially available anti-AR-V7 antibodies and establish reliable AR-V7 immunocytostaining applicable to CTCs from prostate cancer (PCa) patients. We compared seven AR-V7 antibodies by western blotting and immmunocytostaining using a set of PCa cell lines with known AR/AR-V7 status. The emerging best antibody was validated for detection of CRPC patient CTCs enriched by negative depletion of leucocytes. The anti-AR-V7 antibody, clone E308L emerged as the best antibody in regard to signal to noise ratio with a specific nuclear signal. Moreover, this antibody detects CRPC CTCs more efficiently compared to an antibody previously shown to detect AR-V7 CTCs. We have determined the best antibody for AR-V7 detection of CTCs, which will open future studies to correlate AR-V7 subcellular localization and potential co-localization with other proteins and cellular structures to patient outcomes.