SURAMIN INHIBITS THE GROWTH OF HUMAN BREAST-CANCER CELL-LINES - STUDIES ON PARENTAL LINES AND CORRESPONDING SUBLINES WITH ACQUIRED DOXORUBICIN RESISTANCE WITH AND WITHOUT EXPRESSION OF P-GLYCOPROTEIN

Suramin at 100 to 800 mu g/ml caused a dose dependent growth inhibitio n in three (Zr-75-1, BT 549 and HS-578T) parental human breast cancel cell lines and their corresponding sublines with acquired doxorubicin (dox) and multi-drug resistance. The effect was significantly more mar ked after 7 days suramin exposure compared with 3 days. The oestrogen and progesterone receptor rich cell line Zr-75-1 was more responsive t o suramin compared with the other two lines. The sublines Zr-75-1-dox and HS-578T-dox with art increased expression of the permeability glyc oprotein (P-gp) demonstrated a significantly decreased cell survival c ompared with corresponding parental cell lines at 3 and 7 days exposur e of suramin, respectively. The subline BT 549-dox with multidrug resi stance without P-gp expression had a significantly impaired response a fter 3 days suramin compared with the parental line. These results ind icate that suramin may be a potential therapeutic agent for the breast cancer patients with P-gp expression and multi-drug resistance.