Forsberg K, Valyi-Nagy I, Heldin C H, Herlyn M, Westermark B
Department of Pathology, University Hospital, Uppsala, Sweden.
Proc Natl Acad Sci U S A. 1993 Jan 15;90(2):393-7. doi: 10.1073/pnas.90.2.393.
Human WM9 melanoma cells, previously shown to be devoid of PDGF expression, were stably transfected with a PDGF-B cDNA under the transcriptional control of a cytomegalovirus promoter. Northern blot analysis revealed high expression of an mRNA of the expected size in the PDGF-B-transfected cells. Synthesis and secretion of PDGF-BB was confirmed by immunoprecipitation. Furthermore, conditioned medium from PDGF-B-transfected cells contained a mitogenic activity for fibroblasts. For analysis of tumor growth in vivo, cells of each type were injected subcutaneously into BALB/c nu/nu mice. Tumors from mice injected with WM9 cells transfected with the vector only contained large necrotic areas; only scant blood vessels with narrow lumina were observed. No connective tissue was present. In the tumors from PDGF-B-transfected WM9 cells, nests of tumor were divided by connective tissue septa. An abundance of blood vessels was observed in the connective tissue septa and within the tumor cell nests. There was a complete absence of necrosis in these tumors. The present results suggest that tumor-derived PDGF-BB is a potent mediator of connective tissue stroma formation. The connective tissue framework that is generated in response to PDGF-BB may form a solid support for newly formed blood vessels and, thereby, facilitate the formation of a functional vascular system in the tumor.
人WM9黑色素瘤细胞先前已被证明缺乏血小板衍生生长因子（PDGF）表达，用受巨细胞病毒启动子转录控制的PDGF-B cDNA进行稳定转染。Northern印迹分析显示，在PDGF-B转染的细胞中，预期大小的mRNA有高表达。通过免疫沉淀证实了PDGF-BB的合成和分泌。此外，来自PDGF-B转染细胞的条件培养基对成纤维细胞具有促有丝分裂活性。为了分析体内肿瘤生长情况，将每种类型的细胞皮下注射到BALB/c裸鼠中。仅注射载体转染的WM9细胞的小鼠肿瘤含有大片坏死区域；仅观察到管腔狭窄的少量血管。不存在结缔组织。在PDGF-B转染的WM9细胞形成的肿瘤中，肿瘤巢被结缔组织间隔分开。在结缔组织间隔和肿瘤细胞巢内观察到大量血管。这些肿瘤完全没有坏死。目前的结果表明，肿瘤衍生的PDGF-BB是结缔组织基质形成的有效介质。响应PDGF-BB产生的结缔组织框架可能为新形成的血管形成坚实的支撑，并由此促进肿瘤中功能性血管系统的形成。
