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Genome wide analysis of Circulating Tumor Cells from Patients with Metastatic Prostate Cancer Reveals Clinically Relevant Aberrations Associated with Castration Resistance

ABSTRACT: The number of circulating tumor cells (CTCs) in metastatic prostate cancer patients provides prognostic and predictive information. However, it is the molecular characterization of CTCs that offers insight into the biology of these tumor cells in the context of personalized treatment. We performed a pilot study to evaluate the feasibility of isolation and genomic profiling of CTCs in castration-resistant prostate cancer. CTCs in 7.5 mLs of blood in 20 castration-resistant metastatic prostate cancer patients were enumerated using CellSearch. Additional 10-20 mLs of blood from 12 patients positive for CTCs were subjected to immunomagnetic enrichment and fluorescence activated cell sorting (IE/FACS) to isolate pools of ~20 CTCs. Genomic DNA of CTCs was subjected to whole genome amplification followed by gene copy number analysis via array comparative genomic hybridization (aCGH). Archival primary tumor biopsy samples available from 2 patients were also subjected to aCGH.

ORGANISM(S): Homo sapiens

PROVIDER: GSE27636 | GEO | 2012/03/08

SECONDARY ACCESSION(S): PRJNA138525

REPOSITORIES: GEO

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Project description:Background. Androgen receptor splice variant-7 (AR-V7) is a truncated form of the androgen receptor protein which lacks the ligand-binding domain, the target of enzalutamide and abiraterone, but remains constitutively active as a transcription factor. We hypothesized that detection of AR-V7 in circulating tumor cells (CTCs) from men with advanced prostate cancer would be associated with resistance to enzalutamide and abiraterone. Methods. We used quantitative reverse-transcription polymerase-chain-reaction (qRT-PCR) to interrogate CTCs for the presence or absence of AR-V7 from prospectively enrolled patients with metastatic castration-resistant prostate cancer initiating treatment with either enzalutamide or abiraterone. We examined associations between AR-V7 status and PSA response rates, PSA-progression-free-survival (PSA-PFS), clinical/radiographic-progression-free-survival (PFS), and overall survival (OS). Multivariable Cox regression analyses were performed to determine the independent effect of AR-V7 status on clinical outcomes. Results. Thirty-one enzalutamide-treated patients and thirty-one abiraterone-treated patients were enrolled, of which 38.7% and 19.4% had detectable AR-V7 from CTCs, respectively. Among men receiving enzalutamide, AR-V7–positive patients had inferior PSA response rates (0% vs 52.6%, P=0.004), PSA-PFS (median: 1.4 vs 6.0 months, P<0.001), PFS (median: 2.1 vs 6.1 months, P<0.001), and OS (median: 5.5 months vs not reached, P=0.002) compared to AR-V7–negative patients. Similarly, among men receiving abiraterone, AR-V7–positive patients had inferior PSA response rates (0% vs 68.0%, P=0.004), PSA-PFS (median: 1.3 months vs not reached, P<0.001), PFS (median: 2.3 months vs not reached, P<0.001), and OS (median: 10.6 months vs not reached, P=0.006). The negative prognostic impact of AR-V7 was maintained after adjusting for full-length-AR expression. Conclusions. Detection of AR-V7 in CTCs from patients with castration-resistant prostate cancer is associated with resistance to enzalutamide and abiraterone. A total of four metastatic castration-resistant prostate tumor samples from four patients were subjected to RNA-seq. Two samples were positive for androgen receptor splice variant 7 and the other two were negative for this variant.

Project description:About 230 clinical trials currently explore the role of circulating tumor cell (CTC) analysis for therapy decisions, but no assays enable comprehensive molecular characterization of CTCs with diagnostic precision. We therefore combined a workflow for CTC enrichment and isolation with 100% purity with a non-random whole genome amplifiation method for single cells and applied it to 510 single CTCs and 189 leukocytes of 66 breast cancer patients. We defined a genome integrity index (GII) to identify cells suited for molecular chracterization by different molecular assay in more than 90% of single cells, such as diagnostic profiling for point mutations, gene amplifications and whole genomes of single cells. The high reliability on clinical samples enabled assessing the molecular heterogeneity of single CTCs of metastatic breast cancer patients. We readily identified therapeutically relevant genomic disparity between primary tumors and CTCs. Microheterogeneity analysis among individual CTCs uncovered preexisting cells reistsant to ERBB2 targeted therapies suggesting ongoing microevolution at late stage disease whose exploration may provide essential information for personalized treatment decisions. The analysis aimed to indentify profiles of copy number changes in genomic DNA of single circulating tumor cells (CTCs). For this, CTCs were enrched using the FDA approved CellSearch System and single-cell were isolated using the DEPArray System. Subsequently, single-cell DNA was amplified using the Ampli1 WGA Kits and subjected to single-cell aCGH analysis according to previously published protocol (Czyz ZT et al., PLoS One. 2014 Jan 21;9(1):e85907). The analysis included 38 single CTCs and 10 white blood cells (WBCs) obtained from 16 breast cancer patient. WBCs were used as controls for the analysis. In addition, four CTC cell pools were included in the analysis. This was done to show the discrepancies between the profiles of individual cells and corresponing average genomic profile of CTCs in a patient material (cell pools), thereby demonstrating the importance of the analysis on the cell-by-cell basis. The reference sample used for all aCGH experiments consisted of a pool of four single-cell WGA products generated from WBCs of a healthy female donor.

Project description:Prostate cancer is initially responsive to androgen deprivation, but the effectiveness of androgen receptor (AR) inhibitors in recurrent disease is variable. Biopsy of bone metastases is challenging, hence sampling circulating tumor cells (CTCs) may reveal drug resistance mechanisms. We established single cell RNA-sequencing profiles of 77 intact CTCs isolated from 13 patients (mean 6 CTCs/patient) using microfluidic enrichment. Single CTCs from each individual display considerable heterogeneity, including expression of AR gene mutations and splicing variants. Retrospective analysis of CTCs from patients progressing on AR inhibitor, compared with untreated cases indicates activation of noncanonical Wnt signaling (P=0.0064). Ectopic expression of Wnt5a in prostate cancer cells attenuates the antiproliferative effect of AR inhibition, while its suppression in drug-resistant cells restores partial sensitivity, a correlation also evident in an established mouse model. Thus, single cell analysis of prostate CTCs reveals heterogeneity in signaling pathways that could contribute to treatment failure. A total of 221 single candidate prostate CTCs were isolated from 18 patients with metastatic prostate cancer and 4 patients with localized prostate cancer. Of these, 133 cells (60%) had RNA of sufficient quality for amplification and next generation RNA sequencing, and 122 (55%) had >100,000 uniquely aligned sequencing reads. In addition to candidate CTCs, we also obtained comprehensive transcriptomes for 12 bulk primary prostate cancers (macrodissected for >70% tumor content), 30 single cells derived from four different prostate cancer cell lines, and 5 patient-derived leukocyte controls. The leukocytes were readily distinguished by their expression of hematopoietic lineage markers and served to exclude any CTCs with potentially contaminating signals. Strict expression thresholds were used to define lineage-confirmed CTCs, scored by prostate lineage-specific genes (PSA, PSMA, AMACR, AR) and standard epithelial markers (KRT7, KRT8, KRT18, KRT19, EpCAM). 28 cells were excluded given the presence of leukocyte transcripts suggestive of cellular contamination or misidentification during selection, and 17 cells were excluded given low expression of both prostate lineage-specific genes and 5 standard epithelial markers. The remaining 77 cells, defined as lineage-confirmed CTCs, displayed expression of either prostate lineage-specific or epithelial genes, and low expression of leukocyte-specific genes, consistent with their tumor of origin.

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Genome wide analysis of Circulating Tumor Cells from Patients with Metastatic Prostate Cancer Reveals Clinically Relevant Aberrations Associated with Castration Resistance

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