Roles of KLF6 and KLF6-SV1 in ovarian cancer progression and intraperitoneal dissemination.
OBJECTIVE
We investigated the role of the KLF6 tumor suppressor gene and its alternatively spliced isoform KLF6-SV1 in epithelial ovarian cancer (EOC).


METHODS
We first analyzed tumors from 68 females with EOC for KLF6 gene inactivation using fluorescent loss of heterozygosity (LOH) analysis and direct DNA sequencing and then defined changes in KLF6 and KLF6-SV1 expression levels by quantitative real-time PCR. We then directly tested the effect of KLF6 and KLF6-SV1 inhibition in SKOV-3 stable cell lines on cellular invasion and proliferation in culture and tumor growth, i.p. dissemination, ascites production, and angiogenesis in vivo using BALB/c nu/nu mice. All statistical tests were two sided.


RESULTS
LOH was present in 59% of samples in a cell type-specific manner, highest in serous (72%) and endometrioid (75%) subtypes, but absent in clear cell tumors. LOH was significantly correlated with tumor stage and grade. In addition, KLF6 expression was decreased in tumors when compared with ovarian surface epithelial cells. In contrast, KLF6-SV1 expression was increased approximately 5-fold and was associated with increased tumor grade regardless of LOH status. Consistent with these findings, KLF6 silencing increased cellular and tumor growth, angiogenesis, and vascular endothelial growth factor expression, i.p. dissemination, and ascites production. Conversely, KLF6-SV1 down-regulation decreased cell proliferation and invasion and completely suppressed in vivo tumor formation.


CONCLUSIONS
Our results show that KLF6 and KLF6-SV1 are associated with key clinical features of EOC and suggest that their therapeutic targeting may alter ovarian cancer growth, progression, and dissemination.
DiFeo
Analisa
A
Department of Human Genetics, Mount Sinai School of Medicine, 1425 Madison Avenue, New York, New York 10029, USA.
Narla
Goutham
G
Hirshfeld
Jennifer
J
Camacho-Vanegas
Olga
O
Narla
Jyothsna
J
Rose
Stephen L
SL
Kalir
Tamara
T
Yao
Shen
S
Levine
Alice
A
Birrer
Michael J
MJ
Bonome
Tomas
T
Friedman
Scott L
SL
Buller
Richard E
RE
Martignetti
John A
JA
D000230:Adenocarcinoma / Q000235:genetics / Q000473:pathology; D004273:DNA, Neoplasm / Q000235:genetics / Q000302:isolation & purification; D018450:Disease Progression; D005260:Female; D005819:Genetic Markers; D006801:Humans; D000075723:Kruppel-Like Factor 6; D051741:Kruppel-Like Transcription Factors / Q000235:genetics / Q000502:physiology*; D019656:Loss of Heterozygosity; D018365:Neoplasm, Residual / Q000235:genetics; D010051:Ovarian Neoplasms / Q000235:genetics* / Q000473:pathology; D016133:Polymerase Chain Reaction; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000502:physiology*; D012334:RNA, Neoplasm / Q000235:genetics; D034741:RNA, Small Interfering
D004273:DNA, Neoplasm; D005819:Genetic Markers; C105465:KLF6 protein, human; D000075723:Kruppel-Like Factor 6; D051741:Kruppel-Like Transcription Factors; D011518:Proto-Oncogene Proteins; D012334:RNA, Neoplasm; D034741:RNA, Small Interfering