Regulation of HSulf-1 expression by variant hepatic nuclear factor 1 in ovarian cancer.
We recently identified HSulf-1 as a down-regulated gene in ovarian carcinomas. Our previous analysis indicated that HSulf-1 inactivation in ovarian cancers is partly mediated by loss of heterozygosity and epigenetic silencing. Here, we show that variant hepatic nuclear factor 1 (vHNF1), encoded by transcription factor 2 gene (TCF2, HNF1beta), negatively regulates HSulf-1 expression in ovarian cancer. Immunoblot assay revealed that vHNF1 is highly expressed in HSulf-1-deficient OV207, SKOV3, and TOV-21G cell lines but not in HSulf-1-expressing OSE, OV167, and OV202 cells. By short hairpin RNA-mediated down-regulation of vHNF1 in TOV-21G cells and transient enhanced vHNF1 expression in OV202 cells, we showed that vHNF1 suppresses HSulf-1 expression in ovarian cancer cell lines. Reporter assay and chromatin immunoprecipitation experiments showed that vHNF1 is specifically recruited to HSulf-1 promoter at two different vHNF1-responsive elements in OV207 and TOV-21G cells. Additionally, down-regulation of vHNF1 expression in OV207 and TOV-21G cells increased cisplatin- or paclitaxel-mediated cytotoxicity as determined by both 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and clonogenic assays and this effect was reversed by down-regulation of HSulf-1. Moreover, nude mice bearing TOV-21G cell xenografts with stably down-regulated vHNF1 were more sensitive to cisplatin- or paclitaxel-induced cytotoxicity compared with xenografts of TOV-21G clonal lines with nontargeted control short hairpin RNA. Finally, immunohistochemical analysis of 501 ovarian tumors including 140 clear-cell tumors on tissue microarrays showed that vHNF1 inversely correlates to HSulf-1 expression. Collectively, these results indicate that vHNF1 acts as a repressor of HSulf-1 expression and might be a molecular target for ovarian cancer therapy.
Liu
Peng
P
Departments of Experimental Pathology, University of British Columbia, Vancouver, British Columbia, Canada.
Khurana
Ashwani
A
Rattan
Ramandeep
R
He
Xiaoping
X
Kalloger
Steve
S
Dowdy
Sean
S
Gilks
Blake
B
Shridhar
Viji
V
D000818:Animals; D002277:Carcinoma / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D051539:Hepatocyte Nuclear Factor 1-beta / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D020411:Oligonucleotide Array Sequence Analysis; D010051:Ovarian Neoplasms / Q000235:genetics* / Q000473:pathology; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000494:pharmacology; D020218:Response Elements; D015238:Sulfotransferases / Q000235:genetics* / Q000502:physiology; D014162:Transfection; D023041:Xenograft Model Antitumor Assays
D034741:RNA, Small Interfering; D051539:Hepatocyte Nuclear Factor 1-beta; C470791:SULF1 protein, human; D015238:Sulfotransferases