Systematic analysis of the TGF-beta/Smad signalling pathway in the rhabdomyosarcoma cell line RD.
Transforming growth factor-beta (TGF-beta) is a multifunctional regulator of cell growth and differentiation, whose actions are highly cell type specific. To study the role of the TGF-beta1 autocrine loop in regulating growth and myogenic differentiation in the human rhabdomyosarcoma cell line, RD, an attempt was made to establish a framework for the expression of several components of TGF-beta1/Smad signalling pathway at the mRNA and protein levels by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis in RD cells compared with the normal myoblasts. Higher exogenous concentration of TGF-beta1 was necessary to reach a growth-inhibition effect, whereas TGF-beta1 downregulated the expression of myosin heavy-chain mRNA at lower concentrations than that was required for growth inhibition. Treatment with TGF-beta1 significantly decreased the number of sarcomeric actin and myosin-expressing cells. In this study, we have shown that RD cells displayed higher expression of TbetaRI, TbetaRII, Smad2 and Smad4 at both the mRNA and protein levels than myoblasts. Smad3 and Smad7 mRNA were expressed at higher level in RD cells than in myoblasts. The staining patterns of TbetaR and Smads suggest that they may transduce different TGF-beta1 signalling in RD cells than in myoblasts. TGF-beta1 signalling induced a rapid relocation of Smad2 to the nucleus; in contrast, Smad4 remained localized to the cytoplasm unless it was coexpressed with Smad2. These studies suggest that signalling from the cell surface to the nucleus through Smad proteins is a required component of TGF-beta1-induced cell response in RD cells. The RD cell line is a suitable model to study the TGF-beta autocrine loop involved in growth and differentiation of RMS.
Wang
Hua
H
Department of Pathology, West China Hospital, Sichuan University, Chengdu, PR China. hxwanghua@21cn.com
Yang
Guang-Hua
GH
Bu
Hong
H
Zhou
Qiao
Q
Guo
Li-Xin
LX
Wang
Shou-Li
SL
Ye
Lv
L
D019898:Autocrine Communication / Q000502:physiology*; D015153:Blotting, Western / Q000379:methods; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D005455:Fluorescent Antibody Technique; D006801:Humans; D018613:Microscopy, Confocal; D018995:Myosin Heavy Chains / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012208:Rhabdomyosarcoma / Q000378:metabolism / Q000473:pathology*; D051785:Smad Proteins; D051899:Smad2 Protein; D051901:Smad4 Protein; D012983:Soft Tissue Neoplasms / Q000378:metabolism / Q000473:pathology*; D018709:Statistics, Nonparametric; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism / Q000494:pharmacology*; D014178:Translocation, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D018125:Receptors, Transforming Growth Factor beta; C497782:SMAD2 protein, human; C497796:SMAD4 protein, human; D051785:Smad Proteins; D051899:Smad2 Protein; D051901:Smad4 Protein; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D018995:Myosin Heavy Chains