Cross-talk between EphA2 and BRaf/CRaf is a key determinant of response to Dasatinib.
OBJECTIVE
EphA2 is an attractive therapeutic target because of its diverse roles in cancer growth and progression. Dasatinib is a multikinase inhibitor that targets EphA2 and other kinases. However, reliable predictive markers and a better understanding of the mechanisms of response to this agent are needed.


METHODS
The effects of dasatinib on human uterine cancer cell lines were examined using a series of in vitro experiments, including MTT, Western blot analysis, and plasmid transfection. In vivo, an orthotopic mouse model of uterine cancer was utilized to identify the biologic effects of dasatinib. Molecular markers for response prediction and the mechanisms relevant to response to dasatinib were identified by using reverse phase protein array (RPPA), immunoprecipitation, and double immunofluorescence staining.


RESULTS
We show that high levels of CAV-1, EphA2 phosphorylation at S897, and the status of PTEN are key determinants of dasatinib response in uterine carcinoma. A set of markers essential for dasatinib response was also identified and includes CRaf, pCRaf(S338), pMAPK(T202/Y204) (mitogen-activated protein kinase [MAPK] pathway), pS6(S240/244), p70S6k(T389) (mTOR pathway), and pAKT(S473). A novel mechanism for response was discovered whereby high expression level of CAV-1 at the plasma membrane disrupts the BRaf/CRaf heterodimer and thus inhibits the activation of MAPK pathway during dasatinib treatment.


CONCLUSIONS
Our in vitro and in vivo results provide a new understanding of EphA2 targeting by dasatinib and identify key predictors of therapeutic response. These findings have implications for ongoing dasatinib-based clinical trials.
Authors' Affiliations: Departments of Gynecologic Oncology and Reproductive Medicine, Hematology and Oncology, Biostatistics, Cancer Biology, and Pathology, and The Center for RNA Interference and Non-Coding RNAs; The University of Texas MD Anderson Cancer Center, Houston, Texas.
Jie
J
Huang
Wei
W
Hu
Justin
J
Bottsford-Miller
Tao
T
Liu
Hee Dong
HD
Han
Behrouz
B
Zand
Sunila
S
Pradeep
Ju-Won
JW
Roh
Duangmani
D
Thanapprapasr
Heather J
HJ
Dalton
Chad V
CV
Pecot
Rajesh
R
Rupaimoole
Chunhua
C
Lu
Bryan
B
Fellman
Diana
D
Urbauer
Yu
Y
Kang
Nicholas B
NB
Jennings
Li
L
Huang
Michael T
MT
Deavers
Russell
R
Broaddus
Robert L
RL
Coleman
Anil K
AK
Sood
D000818:Animals; D045744:Cell Line, Tumor; D000069439:Dasatinib; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D051379:Mice; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage; D055503:Protein Multimerization / Q000187:drug effects; D048493:Proto-Oncogene Proteins B-raf / Q000737:chemistry / Q000378:metabolism*; D019908:Proto-Oncogene Proteins c-raf / Q000737:chemistry / Q000378:metabolism*; D011743:Pyrimidines / Q000008:administration & dosage*; D036104:Receptor, EphA2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013844:Thiazoles / Q000008:administration & dosage*; D014594:Uterine Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology
D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D013844:Thiazoles; D036104:Receptor, EphA2; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D019908:Proto-Oncogene Proteins c-raf; D000069439:Dasatinib