title: Combination of pigment epithelium-derived factor  with radiotherapy enhances the antitumor effects on  nasopharyngeal carcinoma by downregulating  vascular endothelial growth factor expression and  angiogenesis.
abstract: Nasopharyngeal carcinoma (NPC), which has the highest incidence in South China, is mainly treated by radiotherapy. However, the survival rate remains low. Angiogenesis is closely correlated with progress of NPC. Thus, the combination of anti-angiogenesis with radiation is an attractive strategy for NPC treatment. A heterogenic xenografted human NPC nude mice model was established to investigate the effect of pigment epithelium-derived factor (PEDF), a potent anti-angiogenic factor, and the combined effect of PEDF and radiotherapy on nasopharyngeal carcinoma. Pigment epithelium- derived factor remarkably suppressed the growth of NPC by 43.52% and decreased the tumor microvessel density (MVD). Pigment epithelium-derived factor had no effects on the proliferation and apoptosis of NPC cell lines by MTT and flow cytometry assay. However, PEDF decreased vascular endothelial growth factor (VEGF) in NPC cell lines by downregulation of hypoxia-inducible factor 1a, a crucial transcriptional factor for VEGF expression, as demonstrated by western blotting and immunofluorescent staining assay. Interestingly, irradiation alone could also effectively downregulate VEGF and MVD of xenografted tumor, which indicates that irradiation suppresses NPC not only by killing tumor cells but also through anti-angiogenesis. Furthermore, combined treatment of PEDF with irradiation enhanced the antitumor efficacy. The MVD and VEGF in the combined therapy were much less than in the treatment with PEDF or radiotherapy alone. Our observation demonstrated that the combination of PEDF with radiotherapy enhances the efficacy of the antitumor effect on NPC by the coordinated inhibition on angiogenesis, which implies the potential role of PEDF as an adjuvant agent for NPC treatment.
authors.affiliation: Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, Guangdong Province, China.
authors.forename: Zumin
authors.initials: Z
authors.lastname: Xu
authors.forename: Shuhuan
authors.initials: S
authors.lastname: Fang
authors.forename: Yufang
authors.initials: Y
authors.lastname: Zuo
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Rui
authors.initials: R
authors.lastname: Cheng
authors.forename: Qingsong
authors.initials: Q
authors.lastname: Wang
authors.forename: Zhonghan
authors.initials: Z
authors.lastname: Yang
authors.forename: Weibin
authors.initials: W
authors.lastname: Cai
authors.forename: Jianxing
authors.initials: J
authors.lastname: Ma
authors.forename: Xia
authors.initials: X
authors.lastname: Yang
authors.forename: Guoquan
authors.initials: G
authors.lastname: Gao
mesh_terms: D020533:Angiogenesis Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002277:Carcinoma; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002681:China; D003131:Combined Modality Therapy; D005136:Eye Proteins / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D055806:Microvessels / Q000187:drug effects; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000098:blood supply / Q000188:drug therapy / Q000532:radiotherapy; D009389:Neovascularization, Pathologic / Q000188:drug therapy; D009414:Nerve Growth Factors / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D015843:Serpins / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D042442:Vascular Endothelial Growth Factors / Q000235:genetics / Q000378:metabolism*; D023041:Xenograft Model Antitumor Assays; D000099174:Pigment Epithelium-Derived Factor
chemical_list: D020533:Angiogenesis Inhibitors; D005136:Eye Proteins; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009414:Nerve Growth Factors; D015843:Serpins; D042442:Vascular Endothelial Growth Factors; D000099174:Pigment Epithelium-Derived Factor