Overexpression of WISP-1 down-regulated motility and invasion of lung cancer cells through inhibition of Rac activation.
Wnt-induced-secreted-protein-1 (WISP-1) is a cysteine-rich, secreted factor belonging to the CCN family. These proteins have been implicated in the inhibition of metastasis; however, the mechanisms involved have not been described. We demonstrated that overexpression of WISP-1 in H460 lung cancer cells inhibited lung metastasis and in vitro cell invasion and motility. We investigated the possibility that WISP-1 may regulate activation of Rac, a small GTPase important for cytoskeletal reorganizations during motility. In an indirect assay, WISP-1-expressing cells exhibited marked reduction in Rac activation compared with control cells. Blocking antibodies to alpha(v)beta(5) and alpha(1) integrins restored Rac activation in WISP-1 cells, suggesting that the inhibitory effect of WISP-1 on Rac lies downstream of integrins. Constitutively activated Rac mutant (RacG12V) was transfected into WISP-1 cells to restore Rac activation and these WISP-1/RacG12V transfectants were used for further studies. We performed microarray and real-time PCR analyses to identify genes involved in invasion that may be differentially regulated by WISP-1. Here, we showed decreased expression of metalloproteinase-1 (MMP-1) in WISP-1 cells compared with controls but increased expression in WISP-1/RacG12V cells. In an invasion assay across collagen I, an MMP-1 target matrix, WISP-1 cells were significantly less invasive compared with controls, whereas WISP-1/RacG12V cells showed elevated invasion levels. This work illustrates a negatively regulated pathway by WISP-1 involving integrins and Rac in the down-regulation of invasion.
Soon
Lilian L
LL
Division of Pulmonary and Critical Care Medicine, Department of Medicine, New York University, New York, New York 10016, USA.
Yie
Ting-An
TA
Shvarts
Anita
A
Levine
Arnold J
AJ
Su
Fei
F
Tchou-Wong
Kam-Meng
KM
D055511:CCN Intercellular Signaling Proteins; D002460:Cell Line; D015536:Down-Regulation; D006133:Growth Substances / Q000235:genetics / Q000502:physiology*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008175:Lung Neoplasms / Q000473:pathology*; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D015513:Oncogene Proteins / Q000235:genetics / Q000502:physiology*; D011518:Proto-Oncogene Proteins; D020744:rac GTP-Binding Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism
D055511:CCN Intercellular Signaling Proteins; C116396:CCN4 protein, human; D006133:Growth Substances; D047908:Intracellular Signaling Peptides and Proteins; D015513:Oncogene Proteins; D011518:Proto-Oncogene Proteins; D020744:rac GTP-Binding Proteins