Nelius T, Martinez-Marin D, Hirsch J, Miller B, Rinard K, Lopez J, de Riese W, Filleur S
Department of Urology, Texas Tech University-Health Sciences Center, 3601 4th Street, Lubbock, TX, USA.
Department of Pathology, Texas Tech University-Health Sciences Center, 3601 4th Street, Lubbock, TX, USA.
Cell Death Dis. 2014 May 8;5(5):e1210. doi: 10.1038/cddis.2014.180.
There is currently no cure for advanced castration-refractory prostate cancer (CRPC) despite the recent approval of several new therapeutic agents. We report here the anti-tumor effect of the angio-inhibitory pigment epithelium-derived factor (PEDF) in the metastatic LNCaP-derivative CRPC CL1 model and explore PEDF anti-neoplasic efficacy in combination with low-dose chemotherapy. Androgen-sensitive LNCaP and CRPC PC3 cell lines were examined as comparison. Using a retroviral expression system, we showed that PEDF limited the proliferation of all prostatic cell lines tested; an effect attributed to interleukin 8 (IL8)-CXCR1/IL8RA inhibition. PEDF also reduced the number and size of 3D tumor spheroids in vitro, but only induced cell differentiation in CRPC spheroids. Similarly, PEDF inhibited the migration of CRPC cells suggesting both anti-proliferative and anti-migratory functions. In vivo, PEDF decreased by 85% and 65% the growth of subcutaneous (s.c.) PC3 and CL1 tumors, respectively. In the CL1 orthotopic model, tumor intake with lethal metastases was found in all animals; nevertheless, PEDF prolonged the median survival of tumor-bearing mice (95% confidence interval: 53 ± 0.001 to 57 ± 1 days). Accordingly, PEDF delayed the emergence of skeletal-related event in intra-tibial xenografts. Next, we evaluated low-dose docetaxel (DTX; 5, 1, 0.5 mg/kg) or cyclophosphamide (CTX; 10-20 mg/kg) on established s.c. PC3 tumors that conditionally express PEDF anti-tumoral epitope/NT3. Although NT3-DTX-5 mg/kg combination was inefficient, NT3-DTX-1 mg/kg and -0.5 mg/kg inhibited by 95% and 87.8%, respectively, tumor growth compared with control and induced tumor stasis. Both NT3-CTX combinations were advantageous. Inversely, PEDF-DTX-5 mg/kg and PEDF-CTX-10 mg/kg delayed the most CL1 tumor growth (15, 11 and 5 days for PEDF-DTX-5 mg/kg, PEDF-CTX-10 mg/kg and single treatments, respectively) with elevated apoptosis and serum thrombospondin-1 as possible mechanism and marker, respectively. As well, both PEDF-CTX-10 mg/kg and PEDF-DTX-5 mg/kg prolonged significantly the survival of tumor-bearing mice compared with single treatments. Metastases were reduced in PEDF-DTX-5 mg/kg compared with other treatments, suggesting that PEDF-DTX delayed metastases formation. Our results advocate that PEDF/low-dose chemotherapy may represent a new therapeutic alternative for CRPC.
尽管最近有几种新的治疗药物获批，但目前晚期去势抵抗性前列腺癌（CRPC）仍无法治愈。我们在此报告血管抑制性色素上皮衍生因子（PEDF）在转移性LNCaP衍生的CRPC CL1模型中的抗肿瘤作用，并探讨PEDF与低剂量化疗联合使用时的抗肿瘤疗效。作为对照，检测了雄激素敏感的LNCaP和CRPC PC3细胞系。使用逆转录病毒表达系统，我们发现PEDF限制了所有测试前列腺细胞系的增殖；这种作用归因于白细胞介素8（IL8）-CXCR1/IL8RA的抑制。PEDF还减少了体外3D肿瘤球体的数量和大小，但仅诱导CRPC球体中的细胞分化。同样，PEDF抑制CRPC细胞的迁移，提示其具有抗增殖和抗迁移功能。在体内，PEDF分别使皮下（s.c.）PC3和CL1肿瘤的生长减少了85%和65%。在CL1原位模型中，所有动物均出现伴有致命转移的肿瘤；然而，PEDF延长了荷瘤小鼠的中位生存期（95%置信区间：53±0.001至57±1天）。相应地，PEDF延迟了胫骨内异种移植中骨相关事件的出现。接下来，我们评估了低剂量多西他赛（DTX；5、1、0.5 mg/kg）或环磷酰胺（CTX；10 - 20 mg/kg）对已建立的条件性表达PEDF抗肿瘤表位/NT3的皮下PC3肿瘤的作用。尽管NT3-DTX-5 mg/kg组合无效，但与对照组相比，NT3-DTX-1 mg/kg和-0.5 mg/kg分别抑制了95%和87.8%的肿瘤生长，并诱导肿瘤停滞。两种NT3-CTX组合均具有优势。相反，PEDF-DTX-5 mg/kg和PEDF-CTX-10 mg/kg最显著地延迟了CL1肿瘤的生长（PEDF-DTX-5 mg/kg、PEDF-CTX-10 mg/kg和单一治疗分别延迟15、11和5天），可能的机制分别是凋亡增加和血清血小板反应蛋白-1升高作为标志物。同样，与单一治疗相比，PEDF-CTX-10 mg/kg和PEDF-DTX-5 mg/kg均显著延长了荷瘤小鼠的生存期。与其他治疗相比，PEDF-DTX-5 mg/kg组的转移减少，提示PEDF-DTX延迟了转移形成。我们的结果表明，PEDF/低剂量化疗可能是CRPC的一种新的治疗选择。
