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. 2017 Mar 13;8(42):71447-71455.
doi: 10.18632/oncotarget.16169. eCollection 2017 Sep 22.

Androgen receptor amplification is concordant between circulating tumor cells and biopsies from men undergoing treatment for metastatic castration resistant prostate cancer

Jennifer Podolak  1 , Kristi Eilers  1 , Timothy Newby  1 , Rachel Slottke  1 , Erin Tucker  1 , Susan B Olson  2 , Hui-Wen Lue  1 , Jack Youngren  3 , Rahul Aggarwal  3 , Eric J Small  3 , Julie N Graff  1 , Joshi J Alumkal  1 , Tomasz M Beer  1 , George V Thomas  1   2
Affiliations

Androgen receptor amplification is concordant between circulating tumor cells and biopsies from men undergoing treatment for metastatic castration resistant prostate cancer

Jennifer Podolak et al. Oncotarget. .

Abstract

Increased AR activity has been shown to be preserved in spatially distinct metastatic tumors from the same patient suggesting the requirement for lineage-specific dependencies for metastatic castration resistant prostate cancer (mCRPC). Amplification of the AR gene is a common mechanism by which mCRPC increase AR activity. To determine whether AR amplification in circulating tumor cells (CTC) could complement metastatic tissue biopsies in men undergoing treatment for mCRPC, we developed a novel two-step assay to isolate CTCs and subsequently analyzed AR amplification status in CTCs and matched biopsy tissue from the same patient by fluorescence in situ hybridization (FISH). AR gene status in CTCs showed strong concordance with AR gene status in matched tissue samples in 24 of 25 patients (Correlation: 96%; Kappa: 0.83; Sensitivity: 100%, Specificity: 83%). Our work demonstrates that AR amplification is conserved between CTCs and biopsies and that CTCs can serve as non-invasive surrogate to document AR amplification in mCRPC.

Keywords: androgen receptor; circulating tumor cells; metastases; metastatic castration resistant prostate cancer; prostate cancer.

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Conflict of interest statement

CONFLICTS OF INTEREST The authors declare that they have no competing interest

Figures

Figure 1
Figure 1. CTC capture and validation in LNCAP and mCRPC patients
(A) Flowchart of CTC isolation, detection and molecular analysis workflow. (B) Left panel: LNCAP cells spiked into blood as a model for CTC capture and assay validation; Middle panel: Patient CTC without AR amplification; Right panel: Patient CTC with AR amplification. Upper panel immunofluorescence: Blue: dapi, Green: CK20, Pink: CD45. Lower panel: AR FISH analysis of cell identified in upper panel. Red: AR signal, green: X CEP control signal.
Figure 2
Figure 2. AR amplification in matched CTCs and biopsies from mCRPC patients
(A) Representative images of paired CTC and biopsy patient samples without AR gene amplification (left) and paired patient samples expressing AR gene amplification (right). Red: AR signal; Green: Cep X control signal. (B) Results of AR gene expression in CTC samples and paired biopsies of all study subjects.
Figure 3
Figure 3. Heterogeneity of amplification in mCRPC patient CTCs
(A) Bar graph representing the percentage of amplified CTCs (red) and non-amplified CTCs (green) found in mCRPC patients. (B) Intra-and interpatient heterogeneity of AR amplification in CTCs in mCRPC patients is shown graphically. Representative images are depicted of weak (yellow), medium (orange) and strong (purple) AR amplification found in mCRPC patient CTCs. See results for details.
Figure 4
Figure 4. Documenting AR Amplification status with sequential CTC and biopsies in mCRPC patients
Sequential CTC analysis correlated with baseline and progression biopsies, with two patients having AR amplification at both timepoints, and one patient developing AR amplification at time of progression.
See this image and copyright information in PMC

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