title: Pigment epithelium-derived factor expression prolongs survival and enhances the cytotoxicity of low-dose chemotherapy in castration-refractory prostate cancer.
abstract: 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.
authors.affiliation: Department of Urology, Texas Tech University-Health Sciences Center, 3601 4th Street, Lubbock, TX, USA.
authors.forename: T
authors.initials: T
authors.lastname: Nelius
authors.affiliation: Department of Urology, Texas Tech University-Health Sciences Center, 3601 4th Street, Lubbock, TX, USA.
authors.forename: D
authors.initials: D
authors.lastname: Martinez-Marin
authors.affiliation: Department of Urology, Texas Tech University-Health Sciences Center, 3601 4th Street, Lubbock, TX, USA.
authors.forename: J
authors.initials: J
authors.lastname: Hirsch
authors.affiliation: Department of Pathology, Texas Tech University-Health Sciences Center, 3601 4th Street, Lubbock, TX, USA.
authors.forename: B
authors.initials: B
authors.lastname: Miller
authors.affiliation: Department of Urology, Texas Tech University-Health Sciences Center, 3601 4th Street, Lubbock, TX, USA.
authors.forename: K
authors.initials: K
authors.lastname: Rinard
authors.affiliation: Department of Urology, Texas Tech University-Health Sciences Center, 3601 4th Street, Lubbock, TX, USA.
authors.forename: J
authors.initials: J
authors.lastname: Lopez
authors.affiliation: Department of Urology, Texas Tech University-Health Sciences Center, 3601 4th Street, Lubbock, TX, USA.
authors.forename: W
authors.initials: W
authors.lastname: de Riese
authors.affiliation: 1] Department of Urology, Texas Tech University-Health Sciences Center, 3601 4th Street, Lubbock, TX, USA [2] Department of Immunology and Molecular Microbiology, Texas Tech University-Health Sciences Center, 3601 4th Street, Lubbock, TX, USA.
authors.forename: S
authors.initials: S
authors.lastname: Filleur
mesh_terms: D059250:Administration, Metronomic; D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage*; D017209:Apoptosis / Q000187:drug effects; D001859:Bone Neoplasms / Q000235:genetics / Q000378:metabolism / Q000517:prevention & control* / Q000556:secondary; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D003520:Cyclophosphamide / Q000008:administration & dosage*; D000077143:Docetaxel; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm; D005136:Eye Proteins / Q000096:biosynthesis* / Q000235:genetics; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009361:Neoplasm Invasiveness; D009414:Nerve Growth Factors / Q000096:biosynthesis* / Q000235:genetics; D064129:Prostatic Neoplasms, Castration-Resistant / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D015843:Serpins / Q000096:biosynthesis* / Q000235:genetics; D043823:Taxoids / Q000008:administration & dosage*; D013997:Time Factors; D014162:Transfection; D047368:Tumor Burden / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays; D000099174:Pigment Epithelium-Derived Factor
chemical_list: D000970:Antineoplastic Agents; D003520:Cyclophosphamide; D000077143:Docetaxel; D005136:Eye Proteins; D009414:Nerve Growth Factors; D015843:Serpins; D043823:Taxoids; D000099174:Pigment Epithelium-Derived Factor