Cyr61 mediates hepatocyte growth factor-dependent tumor cell growth, migration, and Akt activation.
Certain tumor cell responses to the growth factor-inducible early response gene product CCN1/Cyr61 overlap with those induced by the hepatocyte growth factor (HGF)/c-Met signaling pathway. In this study, we investigate if Cyr61 is a downstream effector of HGF/c-Met pathway activation in human glioma cells. A semiquantitative immunohistochemical analysis of 112 human glioma and normal brain specimens showed that levels of tumor-associated Cyr61 protein correlate with tumor grade (P < 0.001) and with c-Met protein expression (r(2) = 0.4791, P < 0.0001). Purified HGF rapidly upregulated Cyr61 mRNA (peak at 30 minutes) and protein expression (peak at 2 hours) in HGF(-)/c-Met(+) human glioma cell lines via a transcription- and translation-dependent mechanism. Conversely, HGF/c-Met pathway inhibitors reduced Cyr61 expression in HGF(+)/c-Met(+) human glioma cell lines in vitro and in HGF(+)/c-Met(+) glioma xenografts. Targeting Cyr61 expression with small interfering RNA (siRNA) inhibited HGF-induced cell migration (P < 0.01) and cell growth (P < 0.001) in vitro. The effect of Cyr61 on HGF-induced Akt pathway activation was also examined. Cyr61 siRNA had no effect on the early phase of HGF-induced Akt phosphorylation (Ser(473)) 30 minutes after stimulation with HGF. Cyr61 siRNA inhibited a second phase of Akt phosphorylation measured 12 hours after cell stimulation with HGF and also inhibited HGF-induced phosphorylation of the Akt target glycogen synthase kinase 3alpha. We treated preestablished subcutaneous glioma xenografts with Cyr61 siRNA or control siRNA by direct intratumoral delivery. Cyr61 siRNA inhibited Cyr61 expression and glioma xenograft growth by up to 40% in a dose-dependent manner (P < 0.05). These results identify a Cyr61-dependent pathway by which c-Met activation mediates cell growth, cell migration, and long-lasting signaling events in glioma cell lines and possibly astroglial malignancies.
Kennedy Krieger Institute, Johns Hopkins School of Medicine, Baltimore, MD, USA.
C Rory
CR
Goodwin
Bachchu
B
Lal
Xin
X
Zhou
Sandra
S
Ho
Shuli
S
Xia
Alexandra
A
Taeger
Jamie
J
Murray
John
J
Laterra
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D048708:Cell Growth Processes / Q000502:physiology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology*; D055515:Cysteine-Rich Protein 61 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D005260:Female; D055785:Gene Knockdown Techniques; D005910:Glioma / Q000235:genetics / Q000378:metabolism / Q000473:pathology* / Q000628:therapy; D017228:Hepatocyte Growth Factor / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D051058:Oncogene Protein v-akt / Q000378:metabolism*; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction; D014162:Transfection; D023041:Xenograft Model Antitumor Assays
D000911:Antibodies, Monoclonal; C501848:CCN1 protein, human; D055515:Cysteine-Rich Protein 61; D034741:RNA, Small Interfering; D017228:Hepatocyte Growth Factor; D019859:Proto-Oncogene Proteins c-met; D051058:Oncogene Protein v-akt