Genetically abnormal circulating cells in lung cancer patients: an antigen-independent fluorescence in situ hybridization-based case-control study

Abstract

Purpose: We performed a study to determine if a fluorescence in situ hybridization (FISH)-based assay using isolated peripheral blood mononuclear cells (PBMCs) with DNA probes targeting specific sites on chromosomes known to have abnormalities in non-small cell lung cancer (NSCLC) cases could detect circulating genetically abnormal cells (CACs).

Experimental design: We evaluated 59 NSCLC cases with stage I through IV disease and 24 controls. PBMCs and matched tumors were hybridized with 2 two-color [3p22.1/CEP3 and 10q22.3 (SP-A)/CEP10) and 2 four-color [CEP3, CEP7, CEP17, and 9p21.3 (URO); and EGFR, c-MYC, 6p11-q11, and 5p15.2 (LAV)] FISH probes. Percentages of cytogenetically abnormal cells (CACs) in peripheral blood and in matched tumor specimens were quantified by using an automated fluorescent scanner. Numbers of CACs were calculated based on the percentage of CACs (defined as PBMCs with genetic abnormalities) per milliliter of blood and expressed per microliter of blood.

Results: Patients with NSCLC had significantly higher numbers of CACs than controls. Mean number of CACs ranged from 7.23 +/- 1.32/microL for deletions of 10q22.3/CEP10 to 45.52 +/- 7.49/microL for deletions of 3p22.1/CEP3. Numbers of CACs with deletions of 3p22.1, 10q22.3, and 9p21.3, and gains of URO, increased significantly from early to advanced stage of disease.

Conclusions: We have developed a sensitive and quantitative antigen-independent FISH-based test for detecting CACs in peripheral blood of patients with NSCLC, which showed a significant correlation with the presence of cancer. If this pilot study can be validated in a larger study, CACs may have a role in the management of patients with NSCLC.

Figure 1

Figure 1A: Calibration curves of actual versus expected recovery at different dilutions of spiked tumor cells showing polysomy (arrows) in a background of normal PBMCs (A) 3p22.1/CEP3 (B) 10q22.3/CEP10 (C) LAV (D) URO probes. X-axis depicts percentage of tumor cells recovered, Y-axis depicts cell dilutions from 0.05–0.0001 (X and Y-axis logarithmic scale).

Figure 2

Figure 2A: Error Bar Plots Showing Percentage Deletions and Gains of EGFR (Y-axis) with the LAV probe set in PBMCs Specimens Obtained from Controls and Cases with NSCLC by Disease Stage (X-axis). Figure 2B: Mean ±SE CACs per μl in controls and cases with NSCLC with chromosomal abnormalities of 3p22.1/CEP3, 10q22.3/CEP10, URO and LAV probes stratified by stage. Note the trend for numbers of CACs for all chromosomal abnormalities to increase from early to advanced stage of NSCLC.

Figure 2

Figure 2A: Error Bar Plots Showing Percentage Deletions and Gains of EGFR (Y-axis) with the LAV probe set in PBMCs Specimens Obtained from Controls and Cases with NSCLC by Disease Stage (X-axis). Figure 2B: Mean ±SE CACs per μl in controls and cases with NSCLC with chromosomal abnormalities of 3p22.1/CEP3, 10q22.3/CEP10, URO and LAV probes stratified by stage. Note the trend for numbers of CACs for all chromosomal abnormalities to increase from early to advanced stage of NSCLC.

Figure 3

Figure 3A: Stage IA adenocarcinoma, (A, B) deletions 3p22.1; (C) deletions 10q22.3; (D) polysomy 10q22.3/CEP10. Figure 3B: Stage IA adenocarcinoma, (A) monosomy 6p11-q12; (B) amplification EGFR, C-myc; (C) trisomy CEP3 and monosomy CEP17; and (D) polysomy CEP3, CEP7, CEP17, and 9p21.3.

Figure 3

Figure 3A: Stage IA adenocarcinoma, (A, B) deletions 3p22.1; (C) deletions 10q22.3; (D) polysomy 10q22.3/CEP10. Figure 3B: Stage IA adenocarcinoma, (A) monosomy 6p11-q12; (B) amplification EGFR, C-myc; (C) trisomy CEP3 and monosomy CEP17; and (D) polysomy CEP3, CEP7, CEP17, and 9p21.3.