title: Wilms' tumor 1 gene expression in hepatocellular carcinoma promotes cell dedifferentiation and resistance to chemotherapy.
abstract: The Wilms' tumor 1 gene (WT1) encodes a transcription factor involved in cell growth and development. As we previously reported, WT1 expression is hardly detectable in normal hepatic tissue but is induced in liver cirrhosis. Although WT1 has been found to be overexpressed in a number of malignancies, the role of WT1 in hepatocarcinogenesis has not been clarified. We found that WT1 is expressed in several human hepatocellular carcinoma (HCC) cell lines, including PLC/PRF/5 and HepG2, and in HCC tumor tissue in 42% of patients. WT1 small interfering RNAs did not affect proliferation rate of HCC cells but abrogated their resistance to anoikis. Transcriptome analysis of PLC/PRF/5 cells after WT1 knockdown showed up-regulation of 251 genes and down-regulation of 321. Ninety percent of the former corresponded to metabolic genes, mostly those characterizing the mature hepatocyte phenotype. On the contrary, genes that decreased upon WT1 inhibition were mainly related to defense against apoptosis, cell cycle, and tumor progression. In agreement with these findings, WT1 expression increased the resistance of liver tumor cells to doxorubicin, a compound used to treat HCC. Interestingly, doxorubicin strongly enhanced WT1 expression in both HCC cells and normal human hepatocytes. Among different chemotherapeutics, induction of WT1 transcription was restricted to topoisomerase 2 inhibitors. When WT1 expression was prohibited, doxorubicin caused a marked increase in caspase-3 activation. In conclusion, WT1 is expressed in a substantial proportion of HCC contributing to tumor progression and resistance to chemotherapy, suggesting that WT1 may be an important target for HCC treatment.
authors.affiliation: Division of Hepatology and Gene Therapy,CIMA and CIBERehd, University Clinic, University of Navarra, Pamplona, Spain.
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Perugorria
authors.forename: Josefa
authors.initials: J
authors.lastname: Castillo
authors.forename: M Ujue
authors.initials: MU
authors.lastname: Latasa
authors.forename: Saioa
authors.initials: S
authors.lastname: Goñi
authors.forename: Victor
authors.initials: V
authors.lastname: Segura
authors.forename: Bruno
authors.initials: B
authors.lastname: Sangro
authors.forename: Jesús
authors.initials: J
authors.lastname: Prieto
authors.forename: Matías A
authors.initials: MA
authors.lastname: Avila
authors.forename: Carmen
authors.initials: C
authors.lastname: Berasain
mesh_terms: D000368:Aged; D017209:Apoptosis / Q000235:genetics; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy / Q000235:genetics* / Q000601:surgery; D002454:Cell Differentiation; D002455:Cell Division / Q000235:genetics; D015536:Down-Regulation; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D055786:Gene Knockout Techniques; D016162:Genes, Wilms Tumor; D006801:Humans; D008099:Liver / Q000473:pathology; D008113:Liver Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D034741:RNA, Small Interfering