Figure 2.

Breast cancer does not endogenously express P3. mRNA was extracted from (A) breast cancer cell lines and (B) primary breast cancer tissue. RT-PCR was performed using P3 primers, which shows lack of P3 mRNA expression in breast cancer cell lines and primary breast cancer. Jurkat and HL-60 leukemia cell lines were used as negative and positive controls, respectively. Primary breast cancer cells from patient tissues, samples Breast 1–3, were obtained by laser capture microdissection (LCM) performed on tumor obtained from patients at the time of surgical resection. Mammaglobin (MGB)-1 was used to confirm analysis of breast cancer cells. β-actin and GAPDH were used as loading controls. C, Immunoblots demonstrate lack of P3 protein in whole cell lysates from 5 different breast cancer cell lines. Gels were loaded with 20 μg of protein. Purified P3 (5 μg) was used as positive control and GAPDH was used as a loading control. D, Immunohistochemistry showing absence of P3 in patient breast cancer tissue (Breast 3). Left panel is an H&E section (200X) showing poorly differentiated carcinoma with admixed neutrophils. Right panel shows positive staining of P3 in the admixed neutrophils but not in the breast cancer cells. The inset (400X) shows a rare tumor cell engulfing a neutrophil. Both images are taken from the same patient and are representative of 5 tissues. Arrowheads indicate neutrophils.