SAPORIN-6 AND LONIDAMINE IN PRIMARY-CELL CULTURES FROM HUMAN BREAST CARCINOMAS - A SYNERGISTIC EFFECT

Lonidamine (LND) is a potential chemotherapeutic agent which can posit ively modulate the efficacy of several antineoplastic agents. The ribo some-inactivating protein Saporin 6 (SO 6), which acts as a rRNA N-gly cosidase and a DNA nuclease, has recently attracted interest as a nove l potential anticancer and antiviral agent. Synergism between LND and SO 6 was previously demonstrated by us in the human metastatic MAST br east cancer cell line in vitro. In the present study, the antiprolifer ative effect of the drugs, either alone or in combination, was investi gated in vitro at various concentrations in 17 primary cell cultures e stablished from patients carrying infiltrating ductal carcinomas of th e breast. Results indicate a strong synergistic effect in 11/17 cases, when LND was administered as a second drug. This is in agreement with previous results in the MAST cell line. Synergism was evident at SO 6 concentrations between 3.3 x 10(-10) and 1.7 x 10(-9) M.