Thrombopoietin-Like Factor in Urinary Extracts of a Patient with Prostatic Adenocarcinoma

E.G. Putintseva, Instituto de Hematología e Inmunología, Apartado 8070, Ciudad de la Habana 8 (Cuba) With great interest we read the report of Winkelmann et al. [1]. The authors suppose that the increased ploidization of the megakaryocytes observed in patients with metastatic tumors is due to the mitogenic or growth factor with thrombopoietin-like activity produced by the tumor itself. We wish to provide some additional evidence in favor of this hypothesis. Thrombopoiesisstimulating factor or thrombopoietin (TPO) and megakaryocyte colony-stimulating factor (MEGCSF) have been detected in plasma or serum [2, 3] and urine [4, 5] of patients with disturbed thrombopoiesis. In the experiment was used the urine of a 76-year-old white male who was 71 years old when prostatic adenocarcinoma and polycy-themia vera (PV) were recognized. The diagnosis of adenocarcinoma was confirmed during the histological studies of biopsy specimens and the current-day criteria of the Po-lycythemia Vera Study Group [6] for the diagnosis of PV were fulfilled. The patient was treated with diethylstilbestrol but no significant improvement was achieved. As a treatment of his hematologic disorder the patient received two courses of 32P and his hematocrit fell to normal levels, but platelet counts remained high and ranged from 400 × 109/1 to 1,200 × 109/1. At the moment of study he did not receive any active treatment and his peripheric blood count showed Hb 142 g/l, Ht 40, platelets 500 X 109/1, WBC 9,4 × 109/1. The serum of this patient, tested for TPO in a mouse bioassay system by measuring the incorporation of 75Se-sele-nomethionine (75SeM) into platelets of assay mice after the method of Penington [7] with slight modification [8], revealed elevated TPO levels (131% of control, p < 0.02). This suggested the existence of high levels of TPO in urine too. Urinary extracts were prepared from the urine of the patient and pooled urines of 3 healthy donors using the method described by Espada and Gutnisky [9]. This method has been developed for the concentration of erythropoietin (EPO), but physicochemical characteristics of TPO and EPO are similar [10], so both are present in urinary preparations. In the case described here urinary EPO did not contribute to the 186 Putintseva/García-Triana Table 1. Comparison of TPO activities present in urinary extracts from healthy donors and a patient with prostatic adenocarcinoma Dose of Percent incorporation of 75SeM into platelets1 p urinary extract injection, mg control patient 2.5 0.121 ± 0.013 (6) 0.184 ± 0.007 (6) < 0.002 5 0.141 ± 0.017 (7) 0.201 ± 0.120 (6) < 0.05