Analyses of merlin/NF2 connection to FAK inhibitor responsiveness in serous ovarian cancer.
OBJECTIVE
Focal adhesion kinase (FAK) is overexpressed in serous ovarian cancer. Loss of merlin, a product of the neurofibromatosis 2 tumor suppressor gene, is being evaluated as a biomarker for FAK inhibitor sensitivity in mesothelioma. Connections between merlin and FAK in ovarian cancer remain undefined.


METHODS
Nine human and two murine ovarian cancer cell lines were analyzed for growth in the presence of a small molecule FAK inhibitor (PF-271, also termed VS-6062) from 0.1 to 1 μM for 72 h. Merlin was evaluated by immunoblotting and immunostaining of a human ovarian tumor tissue array. Growth of cells was analyzed in an orthotopic tumor model and evaluated in vitro after stable shRNA-mediated merlin knockdown.


RESULTS
Greater than 50% inhibition of OVCAR8, HEY, and ID8-IP ovarian carcinoma cell growth occurred with 0.1 μM PF-271 in anchorage-independent (p<0.001) but not in adherent culture conditions. PF-271-mediated reduction in FAK Y397 phosphorylation occurred independently of growth inhibition. Suspended growth of OVCAR3, OVCAR10, IGROV1, IGROV1-IP, SKOV3, SKOV3-IP, A2780, and 5009-MOVCAR was not affected by 0.1 μM PF-271. Merlin expression did not correlate with serous ovarian tumor grade or stage. PF-271 (30 mg/kg, BID) did not inhibit 5009-MOVCAR tumor growth and merlin knockdown in SKOV3-IP and OVCAR10 cells did not alter suspended cell growth upon PF-271 addition.


CONCLUSIONS
Differential responsiveness to FAK inhibitor treatment was observed. Intrinsic low merlin protein level correlated with PF-271-mediated anchorage-independent growth inhibition, but reduction in merlin expression did not induce sensitivity to FAK inhibition. Merlin levels may be useful for patient stratification in FAK inhibitor trials.
Department of Reproductive Medicine, UCSD Moores Cancer Center, La Jolla, CA 92093, United States.
Nina R
NR
Shah
Department of Reproductive Medicine, UCSD Moores Cancer Center, La Jolla, CA 92093, United States.
Isabelle
I
Tancioni
Department of Reproductive Medicine, UCSD Moores Cancer Center, La Jolla, CA 92093, United States.
Kristy K
KK
Ward
Department of Reproductive Medicine, UCSD Moores Cancer Center, La Jolla, CA 92093, United States.
Christine
C
Lawson
Department of Reproductive Medicine, UCSD Moores Cancer Center, La Jolla, CA 92093, United States.
Xiao Lei
XL
Chen
Department of Reproductive Medicine, UCSD Moores Cancer Center, La Jolla, CA 92093, United States.
Christine
C
Jean
Department of Reproductive Medicine, UCSD Moores Cancer Center, La Jolla, CA 92093, United States.
Florian J
FJ
Sulzmaier
Department of Reproductive Medicine, UCSD Moores Cancer Center, La Jolla, CA 92093, United States.
Sean
S
Uryu
Department of Reproductive Medicine, UCSD Moores Cancer Center, La Jolla, CA 92093, United States.
Nichol L G
NL
Miller
Developmental Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, United States.
Denise C
DC
Connolly
Department of Reproductive Medicine, UCSD Moores Cancer Center, La Jolla, CA 92093, United States. Electronic address: dschlaepfer@ucsd.edu.
David D
DD
Schlaepfer
D000818:Animals; D014408:Biomarkers, Tumor / Q000378:metabolism; D045744:Cell Line, Tumor; D018284:Cystadenocarcinoma, Serous / Q000188:drug therapy* / Q000201:enzymology / Q000378:metabolism; D005260:Female; D051417:Focal Adhesion Kinase 1 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D055785:Gene Knockdown Techniques; D006801:Humans; D051379:Mice; D025581:Neurofibromin 2 / Q000235:genetics / Q000378:metabolism*; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*
D014408:Biomarkers, Tumor; D025581:Neurofibromin 2; D047428:Protein Kinase Inhibitors; D051417:Focal Adhesion Kinase 1; C496050:PTK2 protein, human; C496051:Ptk2 protein, mouse
Biomarker; Focal adhesion kinase; Merlin; Ovarian cancer; Tumor