Taulli Riccardo, Scuoppo Claudio, Bersani Francesca, Accornero Paolo, Forni Paolo E, Miretti Silvia, Grinza Alberto, Allegra Paola, Schmitt-Ney Michel, Crepaldi Tiziana, Ponzetto Carola
Center for Experimental Research and Medical Studies (CERMS), University of Turin, Turin, Italy.
Cancer Res. 2006 May 1;66(9):4742-9. doi: 10.1158/0008-5472.CAN-05-4292.
Rhabdomyosarcoma (RMS) is a highly malignant soft-tissue tumor of childhood deriving from skeletal muscle cells. RMS can be classified in two major histologic subtypes: embryonal (ERMS) and alveolar (ARMS), the latter being characterized by the PAX3/7-FKHR translocation. Here we first investigated whether the Met receptor, a transcriptional target of PAX3 and PAX7, has a role in PAX3-FKHR-mediated transformation. Following PAX3-FKHR transduction, Met was up-regulated in mouse embryonal fibroblasts (MEF), NIH 3T3 and C2C12 cells, and they all acquired anchorage independence. This property was lost in low serum but addition of hepatocyte growth factor/scatter factor (HGF/SF) rescued soft-agar growth. Genetic proof that Met is necessary for this PAX3-FKHR-mediated effect was obtained by transducing with PAX3-FKHR MEFs derived from Met mutant (Met(D/D)) and wild-type (Met(+/+)) embryos. Only Met(+/+) MEFs acquired anchorage-independent growth whereas PAX3-FKHR-transduced Met(D/D) cells were unable to form colonies in soft agar. To verify if Met had a role in RMS maintenance, we silenced the receptor by transducing ERMS and ARMS cell lines with an inducible lentivirus expressing an anti-Met short hairpin RNA (shRNA). Met down-regulation significantly affected RMS cells proliferation, survival, invasiveness, and anchorage-independent growth. Finally, induction of the Met-directed shRNA promoted a dramatic reduction of tumor mass in a xenograft model of RMS. Our data show that both ARMS- and ERMS-derived cell lines, in spite of the genetic drift which may have occurred in years of culture, seem to have retained an "addiction" to the Met oncogene and suggest that Met may represent a target of choice to develop novel therapeutic strategies for ARMS.
横纹肌肉瘤(RMS)是一种源自骨骼肌细胞的儿童高度恶性软组织肿瘤。RMS可分为两种主要的组织学亚型:胚胎型(ERMS)和肺泡型(ARMS),后者的特征是PAX3/7-FKHR易位。在此,我们首先研究了作为PAX3和PAX7转录靶点的Met受体是否在PAX3-FKHR介导的转化中起作用。在转导PAX3-FKHR后,Met在小鼠胚胎成纤维细胞(MEF)、NIH 3T3和C2C12细胞中上调,并且它们都获得了锚定非依赖性。这种特性在低血清中丧失,但添加肝细胞生长因子/分散因子(HGF/SF)可挽救软琼脂生长。通过用源自Met突变体(Met(D/D))和野生型(Met(+/+))胚胎的PAX3-FKHR转导MEF,获得了Met对于这种PAX3-FKHR介导的效应是必需的遗传学证据。只有Met(+/+) MEF获得了锚定非依赖性生长,而PAX3-FKHR转导的Met(D/D)细胞在软琼脂中无法形成集落。为了验证Met是否在RMS维持中起作用,我们通过用表达抗Met短发夹RNA(shRNA)的诱导型慢病毒转导ERMS和ARMS细胞系来沉默该受体。Met下调显著影响RMS细胞的增殖、存活、侵袭和锚定非依赖性生长。最后,在RMS的异种移植模型中,诱导Met靶向的shRNA促进了肿瘤块的显著减少。我们的数据表明,尽管在多年培养中可能发生了基因漂移,但源自ARMS和ERMS两种细胞系似乎都保留了对Met癌基因的“依赖性”,并表明Met可能是开发ARMS新治疗策略的首选靶点。