ATRA Sensitivity in Breast Cancer

Tissue cultures of primary breast tumors were performed as described (van der Kuip et al, 2006 (link)). Briefly, tissue slices (thickness, 200 μm) deriving from surgical specimens of 45 breast cancer patients who underwent a diagnostic Tru-cut procedure were challenged with vehicle (DMSO) or ATRA (0.1 μM) for 48 h in Mammary Epithelial Cell Growth Medium (Lonza, Allendale, NJ). At the end of the treatment, samples were fixed, paraffin-included, and dissected into 5-μm slices, which were subjected to immuno-histochemical staining with an antibody targeting the Ki67 proliferation-associated marker. The percentage of Ki67-positive tumor cells in the various samples was assessed in a quantitative manner by automatic image analysis, and the results are illustrated. Scoring of Ki67 was blinded as to treatment. Each value represents the mean ± SE of at least five separate fields for each experimental sample. The fresh primary tumor samples used for the short-term tissue slice cultures aimed at assessing ATRA sensitivity were supplied by Fondazione S. Maugeri, Pavia. All the procedures were approved by the internal ethical committee of the Fondazione S. Maugeri, and an informed consent for the donation of the sample was obtained from patients.