Changes In Membrane Physicochemical Properties Of Hyperreactive Platelets In Estrogen-Treated Prostatic Cancer

Abstract

Aggregation and physicochemical properties of platelets from 5 prostatic cancer patients, 20 prostatic cancer on estrogen (300 mg stilbesterol diphosphate/day p.o.), 16 of the same patients given 300 mg aspirin/day, 19 prostatic hypertrophy and 21 aged males were examined. Prostatic cancer on estrogen show higher platelet aggregabilities towards ADP, adrenaline, and collagen than the other groups tested. Mean platelet electrophoretic mobilities were determined by the automatic Laser Zee 3000 system and the value for prostatic cancer on estrogen was -1.632±0.0182 um/sec/V/cm (mean ±SE). significantly higher (p <0.001)than the values for prostatic cancer not on estrogen, prostatic hypertrophy, and aged males with values of -1.534±0.0328, -1.526±0.009, and -1.535±0.012 um/sec/V/cm respectively. Electrophoretic mobility was a linear function of whole platelet sialic acid (r=0.96,n=66). The result suggests that the electrophoretic mobility of platelets was defined by sialic acid amount and there may be a selective consumption of platelets with less surface negative charge in prostatic cancer on estrogen. Membrane glycoprotein patterns determined by SDS-polyacrylamide gel electrophoresis showed prostatic cancer on estrogen to have lower glycoprotein I and higher glycoprotein IV than other groups (p < 0.05). There may be factors affecting changes on platelet membranes or population in such patients. Prostatic cancer on estrogen and aspirin had increased mobilities in 14 out of 16 cases with loss of linear relationship between mobility but no changes in sialic acid or glycoprotein pattern from those before aspirin. In vitro incubation of PRP with aspirin resulted in dose dependent increase in mobility with concomitant aggregability loss. The effect suggests another kind of inhibitory mechanism on platelet aggregation in addition to cyclooxygenase inhibition.