Antisense suppression of pygopus2 results in growth arrest of epithelial ovarian cancer.
OBJECTIVE
The Pygopus proteins are critical elements of the canonical Wnt/beta-catenin transcriptional complex. In epithelial ovarian cancer, constitutively active Wnt signaling is restricted to one (endometrioid) tumor subtype. The purpose of this study was to determine the level of expression and growth requirements of human Pygopus2 (hPygo2) protein in epithelial ovarian cancer.


METHODS
Expression and subcellular localization of hPygo2 was determined in epithelial ovarian cancer cell lines and tumors using Northern blot, immunoblot, and immunofluorescence. Immunohistochemistry was done on 125 archived patient epithelial ovarian cancer tumors representing all epithelial ovarian cancer subtypes. T-cell factor-dependent transcription levels were determined in epithelial ovarian cancer cells using TOPflash/FOPflash in vivo assays. Phosphorothioated antisense oligonucleotides were transfected into cell lines and growth assayed by cell counting, anchorage-independent colony formation on soft agar, and xenografting into severe combined immunodeficient mice.


RESULTS
All six epithelial ovarian cancer cell lines and 82% of the patient samples overexpressed nuclear hPygo2 compared with control cells and benign disease. Depletion of hPygo2 by antisense oligonucleotides in both Wnt-active (TOV-112D) and Wnt-inactive serous (OVCAR-3, SKOV-3) and clear cell (TOV-21G) carcinoma cell lines halted growth, assessed using tissue culture, anchorage-independent, and xenograft assays.


CONCLUSIONS
hPygo2 is unexpectedly widely expressed in, and required in the absence of, Wnt signaling for malignant growth of epithelial ovarian cancer, the deadliest gynecologic malignancy. These findings strongly suggest that inhibition of hPygo2 may be of therapeutic benefit for treating this disease.
Popadiuk
Cathy M
CM
Terry Fox Cancer Research Laboratories, Division of Basic Medical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland, Canada.
Xiong
Jieying
J
Wells
Malcolm G
MG
Andrews
Phillip G
PG
Dankwa
Kweku
K
Hirasawa
Kensuke
K
Lake
Blue B
BB
Kao
Kenneth R
KR
D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004195:Disease Models, Animal; D004354:Drug Screening Assays, Antitumor; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000235:genetics; D006801:Humans; D066298:In Vitro Techniques; D047908:Intracellular Signaling Peptides and Proteins / Q000187:drug effects* / Q000235:genetics; D051379:Mice; D009374:Neoplasms, Experimental / Q000628:therapy; D009375:Neoplasms, Glandular and Epithelial / Q000188:drug therapy*; D020319:Oligodeoxyribonucleotides, Antisense / Q000494:pharmacology*; D010051:Ovarian Neoplasms / Q000188:drug therapy*; D013329:Structure-Activity Relationship; D014183:Transplantation, Heterologous; D023041:Xenograft Model Antitumor Assays
D047908:Intracellular Signaling Peptides and Proteins; D020319:Oligodeoxyribonucleotides, Antisense; C453401:PYGO2 protein, human