Fig. 5

Chemoresistance is amplified by obesity and major vault protein (MVP) expression is upregulated at the invasive front of human breast tumors. a Neutral lipid content using bodipy staining (in green) and morphological analyses (transmission, TRANS) of mammary adipocytes embedded in a fibrinogen matrix, isolated from normal weight (NW) or obese patients (scale bars, 100 μm, pictures were taken at day 4 (D4) and day 6 (D6) of culture). Each image shows a maximum projection of about 10 pictures of a z-stack with a distance of 5 μm between each scanning position. b Viability assays after doxorubicin (DOX) exposure of MDA-MB436 breast cancer cell line cocultivated (C), or not (NC), with adipocytes from NW or obese women (n = 5 independent samples). Results are expressed as the ratio of surviving cells in C versus NC cells (set at 1). c Quantification of intracellular fluorescence of DOX in MDA-MB436 cells either non-cocultivated or cocultivated with adipocytes from NW or obese women (n = 5 independent samples) by flow cytometry at indicated times after DOX exposure. d Immunoblots against MVP in MDA-MB436 cells either non-cocultivated or cocultivated with adipocytes from NW or obese women. Tubulin is shown as a control for equal protein loading. Quantification of MVP is shown in arbitrary units. e Histologic examination of a human breast tumor (patient #15) after MVP staining (in brown); (Front) zoom of the MVP staining at the invasive front in one representative area; (Center) zoom of the MVP staining in the center of the tumor in one representative area. In situ carcinoma (black stars) and normal mammary glands (arrowheads) are considered positive and negative internal control, respectively. Note that the quantification did not take into account in situ carcinoma areas. f The ratio of MVP expression between the invasive front and the tumor center was calculated after quantification using Fiji software plug-ins. The results obtained in lean and overweight/obese patients are shown, and each point represents a different patient. Note that, for the clarity of the figure, two patients with ratios greater than 3 (one lean and one obese) are not represented in the figure.