TY - JOUR
T1 - The tumor-suppressor gene ARHI (DIRAS3) suppresses ovarian cancer cell migration through inhibition of the Stat3 and FAK/Rho signaling pathways
AU - Badgwell, D. B.
AU - Lu, Z.
AU - Le, K.
AU - Gao, F.
AU - Yang, M.
AU - Suh, G. K.
AU - Bao, J. J.
AU - Das, P.
AU - Andreeff, M.
AU - Chen, W.
AU - Yu, Y.
AU - Ahmed, A. A.
AU - S-L Liao, W.
AU - Bast, R. C.
N1 - Funding Information:
This work was supported by Grants NCI P01 CA064602 and 1RO1 CA135354-01 from the National Institutes of Health. We also acknowledge the support of the MD Anderson SPORE in Ovarian Cancer 5P50 CA83639 and the CCSG shared resources funded, in part, by CA 5 P30 CA016672. Support was also provided by the Ovarian Cancer Research Fund through a Program Project Award. DBB was supported by an Excellence Award from the Ovarian Cancer Research Fund. AAA was supported by a Cancer Research UK Clinician Scientist fellowship. We thank Jodie Polan for excellent technical support with confocal microscopy and Jared Burks from the Flow Cytometry and Cell Imaging core laboratory for the live-cell time-lapse microscopy partially supported by the MD Anderson Cancer Center CCSG NCI P30 CA16672.
PY - 2012/1/5
Y1 - 2012/1/5
N2 - Ovarian cancers migrate and metastasize over the surface of the peritoneal cavity. Consequently, dysregulation of mechanisms that limit cell migration may be particularly important in the pathogenesis of the disease. ARHI is an imprinted tumor-suppressor gene that is downregulated in >60% of ovarian cancers, and its loss is associated with decreased progression-free survival. ARHI encodes a 26-kDa GTPase with homology to Ras. In contrast to Ras, ARHI inhibits cell growth, but whether it also regulates cell motility has not been studied previously. Here we report that re-expression of ARHI decreases the motility of IL-6-and epidermal growth factor (EGF)-stimulated SKOv3 and Hey ovarian cancer cells, inhibiting both chemotaxis and haptotaxis. ARHI binds to and sequesters Stat3 in the cytoplasm, preventing its translocation to the nucleus and localization in focal adhesion complexes. Stat3 siRNA or the JAK2 inhibitor AG490 produced similar inhibition of motility. However, the combination of ARHI expression with Stat3 knockdown or inhibition produced greatest inhibition in ovarian cancer cell migration, consistent with Stat3-dependent and Stat3-independent mechanisms. Consistent with two distinct signaling pathways, knockdown of Stat3 selectively inhibited IL-6-stimulated migration, whereas knockdown of focal adhesion kinase (FAK) preferentially inhibited EGF-stimulated migration. In EGF-stimulated ovarian cancer cells, re-expression of ARHI inhibited FAK Y397 and Src Y416 phosphorylation, disrupted focal adhesions, and blocked FAK-mediated RhoA signaling, resulting in decreased levels of GTP-RhoA. Re-expression of ARHI also disrupted the formation of actin stress fibers in a FAK-and RhoA-dependent manner. Thus, ARHI has a critical and previously uncharacterized role in the regulation of ovarian cancer cell migration, exerting inhibitory effects on two distinct signaling pathways.
AB - Ovarian cancers migrate and metastasize over the surface of the peritoneal cavity. Consequently, dysregulation of mechanisms that limit cell migration may be particularly important in the pathogenesis of the disease. ARHI is an imprinted tumor-suppressor gene that is downregulated in >60% of ovarian cancers, and its loss is associated with decreased progression-free survival. ARHI encodes a 26-kDa GTPase with homology to Ras. In contrast to Ras, ARHI inhibits cell growth, but whether it also regulates cell motility has not been studied previously. Here we report that re-expression of ARHI decreases the motility of IL-6-and epidermal growth factor (EGF)-stimulated SKOv3 and Hey ovarian cancer cells, inhibiting both chemotaxis and haptotaxis. ARHI binds to and sequesters Stat3 in the cytoplasm, preventing its translocation to the nucleus and localization in focal adhesion complexes. Stat3 siRNA or the JAK2 inhibitor AG490 produced similar inhibition of motility. However, the combination of ARHI expression with Stat3 knockdown or inhibition produced greatest inhibition in ovarian cancer cell migration, consistent with Stat3-dependent and Stat3-independent mechanisms. Consistent with two distinct signaling pathways, knockdown of Stat3 selectively inhibited IL-6-stimulated migration, whereas knockdown of focal adhesion kinase (FAK) preferentially inhibited EGF-stimulated migration. In EGF-stimulated ovarian cancer cells, re-expression of ARHI inhibited FAK Y397 and Src Y416 phosphorylation, disrupted focal adhesions, and blocked FAK-mediated RhoA signaling, resulting in decreased levels of GTP-RhoA. Re-expression of ARHI also disrupted the formation of actin stress fibers in a FAK-and RhoA-dependent manner. Thus, ARHI has a critical and previously uncharacterized role in the regulation of ovarian cancer cell migration, exerting inhibitory effects on two distinct signaling pathways.
KW - RhoA GTPase
KW - Stat3
KW - cytoskeleton
KW - migration suppression
KW - tumor-suppressor gene ARHI
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U2 - 10.1038/onc.2011.213
DO - 10.1038/onc.2011.213
M3 - Article
C2 - 21643014
AN - SCOPUS:84855355011
SN - 0950-9232
VL - 31
SP - 68
EP - 79
JO - Oncogene
JF - Oncogene
IS - 1
ER -