Effects of transforming growth factor beta 1 on the growth of rhabdomyosarcoma cell line RD.
BACKGROUND
Transforming growth factor-beta (TGF-beta) can inhibit the growth of most epithelial and endothelial cells. The growth regulative role of TGF-beta on soft tissue sarcoma was seldom reported. Here we examined TGF-beta1 effects on the growth of human rhabdomyosarcoma cell RD and searched the relative molecular mechanism.


METHODS
The viability of RD was examined by [(3)H]-thymidine incorporation and [3-(4,5-dimethylthiazol-z-yl)-2,5-diphenyl tetrazolium bromide] (MTT) assay. RD cell cycle was analysed by flow cytometry. The protein and mRNA of cell cycle regulative factors in RD were detected by Western blot and reverse transcription-polymerase chain reaction (RT-PCR), respectively. The kinase activity of cdk2 or cdk4 was examined by immunoprecipitation and kinase assay. Immunofluorescent staining was used to detect the location of cell cycle regulative factors in RD by laser scanning confocal microscope.


RESULTS
TGF-beta1 inhibits RD proliferation by G1-arrest in cell cycle progression. TGF-beta1 can prominently up-regulate P27 of RD, then augment P27 to bind cyclinE-cdk2 complexes, which effectively suppress cdk2 kinase activity. P21 increased and c-myc decreased in RD due to TGF-beta1. Both P15 and cdk4 have not been involved in the growth inhibitory event. TGF-beta1 treatment induced P27 to congregate around nucleus. P21 pervaded from nucleus to both nucleus and cytoplasm by TGF-beta1 treatment.


CONCLUSIONS
TGF-beta1 inhibits the proliferation of human rhabdomyosarcoma cell line RD and induces RD G1-arrest. This course is accomplished by TGF-beta1 up-regulating P27 to suppress cdk2 kinase activity. The induction of P21 and down-regulation of C-myc might participate in the growth-arrest event.
Ye
Lü
L
Department of Pathology, West China Hospital, Sichuan University, Chengdu 610041, China.
Zhang
Hong-ying
HY
Wang
Hua
H
Yang
Guang-hua
GH
Bu
Hong
H
Zhang
Li
L
Wang
Shou-li
SL
D018797:Cell Cycle Proteins / Q000032:analysis / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D050760:Cyclin-Dependent Kinase Inhibitor p27; D016193:G1 Phase / Q000187:drug effects; D016259:Genes, myc; D006801:Humans; D012333:RNA, Messenger / Q000032:analysis; D012208:Rhabdomyosarcoma / Q000473:pathology*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1; D025521:Tumor Suppressor Proteins / Q000032:analysis / Q000235:genetics
D018797:Cell Cycle Proteins; D012333:RNA, Messenger; C508960:TGFB1 protein, human; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27