Figure 5.

The SORE6 Reporter Marks a Minority Population with Enhanced Tumor-Initiating Activity in Primary Cultures from Human Breast Cancer

(A) Explant cultures of three independent primary human breast cancers were transduced with the SORE6-GFP reporter or minCMVp-GFP control lentivirus, and the SORE6⁺ population was assessed by FACS.

(B) FACS plots showing that SORE6⁺ cells from the primary human breast cancer culture CBOT1 can regenerate significant numbers of SORE6⁻ cells after 3 days in culture.

(C) Relative enrichment of SORE6⁺ cells for tumor-initiating ability in the primary human breast cancer cultures, assessed by implantation of sorted cells in vivo. Two independent experiments were performed. In experiment #2, stem cell frequencies were calculated using ELDA software.

(D) Confocal z stack image (50 μm depth) of freshly excised xenografted tumor derived from SORE6⁺ primary human breast cancer cells showing green SORE6⁺ cells in clusters at the edge of the tumor (arrows). Blue represents DAPI-stained nuclei. Scale bar, 100 μm.

(E) Deeper (250 μm) confocal z stack image showing SORE6⁺ cells (arrow) at edge of tumor. Blue indicates tumor as visualized by second harmonic generation, since DAPI could not penetrate to sufficient depth. Scale bar, 100 μm.