Tumor growth inhibitory effects of SMANCS, a poly (styrene-maleic acid) conjugated derivative of neocarzinostatin, on various tissue culture cells

Growth inhibitory effects of neocarzinostatin (NCS), and its conjugated derivative with poly (styrene-maleic acid), SMANCS, were examined on various tissue culture cells consisting of 13 lymphatic and 7 non-lymphatic cells (15 cell lines, 5 primary culture cells; 14 in suspension culture cells, 6 in monolayer cells). Both agents showed almost similar concentrations for the growth inhibition against 5 non-lymphatic cell lines (an average minimum growth inhibitory concentration of NCS, 0.076 microgram/ml, and SMANCS, 0.094 microgram/ml, a ratio of 1 : 1.24 (W/W), or 1.0 : 0.9 (mol/mol]. However, SMANCS showed a much less growth inhibitory effects against lymphatic 10 cell lines than NCS. Namely, an average 50% growth inhibitory concentration of NCS was 0.019 microgram/ml whereas that of SMANCS was 0.091 microgram/ml (a ratio of 1 : 4.79). From the consideration of each molecular weight, this ratio is 1 : 3.6. Similar results were obtained in experiments in which 2 primary non-lymphatic cells and 3 primary lymphatic cells were used. Although the largest drawback with NCS was known to be leukopenia, present results indicated the less toxicity of SMANCS than NCS on lymphatic cells and may provide a positive aspect of the new derivative, such as less incidence of leukopenia.