Lagonigro M S, Tamborini E, Negri T, Staurengo S, Dagrada G P, Miselli F, Gabanti E, Greco A, Casali P G, Carbone A, Pierotti M A, Pilotti S
Experimental Molecular Pathology, Istituto Nazionale per lo Studio e la Cura dei Tumori, Milan, Italy.
J Pathol. 2006 Apr;208(5):615-23. doi: 10.1002/path.1945.
Chondrosarcomas represent 20% of all primary bone sarcomas, and many studies have attempted to unravel molecular targets for future development of new therapies. The aim of this study was to investigate the expression/activation of PDGFRalpha, PDGFRbeta and KIT receptor tyrosine kinases (RTKs) as potential therapeutic targets in conventional central primary chondrosarcomas (CCS). The expression of PDGFRalpha, PDGFRbeta and KIT RTKs was detected in 16 CCSs using immunohistochemistry (IHC), and their level of expression and activation status were analysed by immunoprecipitation and western blot experiments. PDGFRalpha, PDGFRbeta and KIT cDNAs were screened to verify the presence of activating mutations and the presence of the cognate ligands was analysed by means of RT-PCR. RTK gene amplification was further studied by means of fluorescence in situ hybridization (FISH) analysis. The immunophenotyping and biochemical analyses showed that the CCSs co-expressed PDGFRalpha and PDGFRbeta, with the latter showing definitively greater protein expression and phosphorylation levels. PDGFRbeta was expressed but not activated in control healthy joint cartilage, in line with no PDGFB detection. Conversely, the KIT gene product did not seem to play a relevant role. These findings, in the absence of activating mutations or an abnormal genomic profile and the presence of PDGFA and PDGFB expression, are consistent with an autocrine/paracrine loop activation of the corresponding receptors. The CCS gene profile described here offers a rationale for the use of RTK inhibitors alone or in combination with chemotherapy, and supports further investigation of RTKs and their downstream signals.
软骨肉瘤占所有原发性骨肉瘤的20%，许多研究试图揭示新疗法未来发展的分子靶点。本研究的目的是调查血小板衍生生长因子受体α（PDGFRα）、血小板衍生生长因子受体β（PDGFRβ）和干细胞因子受体（KIT）受体酪氨酸激酶（RTK）作为传统中央型原发性软骨肉瘤（CCS）潜在治疗靶点的表达/激活情况。采用免疫组织化学（IHC）方法检测了16例CCS中PDGFRα、PDGFRβ和KIT RTK的表达，并通过免疫沉淀和蛋白质印迹实验分析了它们的表达水平和激活状态。对PDGFRα、PDGFRβ和KIT的互补DNA进行筛查以验证激活突变的存在，并通过逆转录聚合酶链反应（RT-PCR）分析同源配体的存在情况。通过荧光原位杂交（FISH）分析进一步研究RTK基因扩增情况。免疫表型分析和生化分析表明，CCS同时表达PDGFRα和PDGFRβ，后者的蛋白表达和磷酸化水平明显更高。PDGFRβ在对照健康关节软骨中表达但未被激活，这与未检测到血小板衍生生长因子B（PDGFB）一致。相反，KIT基因产物似乎没有发挥相关作用。在没有激活突变或异常基因组图谱且存在血小板衍生生长因子A（PDGFA）和PDGFB表达的情况下，这些发现与相应受体的自分泌/旁分泌环激活一致。本文描述的CCS基因图谱为单独使用RTK抑制剂或与化疗联合使用提供了理论依据，并支持对RTKs及其下游信号进行进一步研究。
