Paclitaxel is more effective than thalidomide in inhibiting LNCaP tumor growth in a prostate cancer model

LNCaP tumors were treated by either administration of paclitaxel, thalidomi de or by orchiectomy in order to determine their relationship with markers pertaining to the process of tumor growth,apoptosis or angiogenesis. Forty mts bearing LNCaP tumors were divided into 4 groups bf 10 and treated by ei ther paclitaxel (20 mg/kg x 5 days); thalidomide (200 mg/kg x 5 days/week x 5 weeks); or orchiectomy. After 6 weeks serum samples were. removed for PS A determination and the animals sacrificed for evaluation of:A) tumor volum e; B) tissue bcl-2, cyclin D, PSA and factor VIII immunohistochemically gra ded (0-5 scale)for marker expression; and C) serum PSA. Comparisons were ma de to untreated LNCaP turners. Statistically significant differences were d etermined using the nonparametric Mann-Whitney test. Paclitaxel produced si gnificant differences in volume (p < 0.001), expression of bcl-2 (p < 0.043 ), cyclin D (p < 0.023), tissue PSA (p < 0.001) and serum PSA (p < 0.019) l evels. Thalidomide altered expression of bcl-2 (p < 0.011) and tissue PSA ( p < 0.002). Orchiectomy altered volume (p < 0.002) and bcl-2 expression (p < 0.001). All three therapies have been suggested for prostate cancer and e ach produced alterations in accepted markers for treatment response (either reduced volume or serum PSA). Paclitaxel significantly influenced the most markers. Of interest was that all treatments, especially thalidomide, a kn own antiangiogenesis agent, reduced factor VIII, although not significantly Evidently each treatment evokes different pathways of activity. (C) 1998 P rous Science. All rights reserved.