Breast cancer MPs carry but do not transfer CD44 to recipient cells.

<p>20 µg total cell lysates of (<b>A</b>) drug sensitive cancer cells (leukaemia, CEM and breast cancer, MCF-7) and their co-cultures; (<b>C</b>) non-malignant cells (breast epithelial cells (MBE), osteoblasts (HO-f) and urothelial (HUC) cells) and their co-cultures; with leukaemic cell-derived VLBMP and breast cancer-derived DXMP both overexpressing P-gp were analyzed by Western blot analysis. (<b>A</b>) CD44 was only detected in the breast cancer DXMP but not in the malignant MCF-7 cell (<b>A</b>), or in any of the non-malignant cells (<b>B</b>) following DXMP co-culture. (<b>A</b>) CD44 was not detected in the leukaemic cell-derived VLBMP, the malignant cells or (<b>B</b>) the non-malignant cells follwoing VLBMP co-culture using the anti-CD44 mAb, clone EPR1013Y. β-actin or α-tubulin or were used as an internal loading control. The Western Blot experiments were repeated at least three times with similar results. (<b>C</b>) <b>Detection of CD44 on breast cancer and leukaemic cells by flow cytometry</b>. MCF-7 (<b>a</b>–<b>b</b>) and DX (<b>c</b>–<b>d</b>) cells were harvested from culture flasks either by scraping (a and c) or by trypsinising (b and d). Leukaemic CEM (<b>e</b>) and VLB₁₀₀ (<b>f</b>) cells were harvested by centrifuging the cell suspension. Cells were surface labelled with anti-CD44 (1∶30) (mAb, clone EPR1013Y) followed by Alexa Fluor 647-conjugated goat anti-rabbit IgG (1∶400). No CD44 was detected on the MCF-7 cells harvested without (<b>a</b>) or with trypsin (<b>b</b>). 75% DX cells harvested without (<b>c</b>) or 46% DX cells harvested with trypsin (<b>d</b>), were detected positive for CD44 with respect to the secondary control by flow cytomtery. Almost equal percentage (3.1–3.5%) of CEM (<b>e</b>) and VLB₁₀₀ (<b>f</b>) cells were detected positive for CD44 with respect to the secondary control. Data are representative of a typical experiment.