title: Expression analysis of 6p22 genomic gain in retinoblastoma.
abstract: To identify gene(s) targeted by 6p22 genomic gain, present in more than 50% retinoblastoma tumors, we used real-time RT-PCR to quantify the expression of seven genes in normal human retina and retinoblastoma. Six genes are located in the quantitative multiplex PCR-defined 0.6 Mb minimal region of gain at 6p22 (DEK, AOF1, TPMT, NHLRC1, KIF13A, and NUP153), and E2F3 is 2 Mb away from the minimal region of gain on 6p22. E2F3, DEK, KIF13A, and NUP153 were most frequently overexpressed in retinoblastoma with 6p genomic gain, compared with the normal adult human retina. E2F3 and DEK mRNA levels were increased in all human tumors showing 6p22 gain, as well as in mouse retinoblastoma induced by SV40 large T antigen expression in developing retina, compared with the normal controls (adult human retina and 7-day-old mouse retina, respectively). Only DEK showed statistically significant correlation of expression and genomic copy number (P = 0.019). E2F3 and DEK, but not NUP153, showed developmental regulation. E2F3 and DEK mRNA overexpression was always associated with protein overexpression, determined by immunoblotting or immunofluorescent staining of primary tumors, relative to the adjacent normal retina. E2F3 was strongly expressed in actively proliferating cells, while DEK was overexpressed in all tumor cells. Taking into account the proliferation-promoting role of E2F3, implication of E2F3 in bladder and prostate cancer, and the translocation and overexpression of DEK in leukemia, we conclude that either DEK or E2F3 (or both) are targeted by the 6p22 gain in retinoblastoma.
authors.affiliation: Department of Molecular and Medical Genetics, University of Toronto, Toronto, ON, Canada.
authors.forename: Marija
authors.initials: M
authors.lastname: Orlic
authors.forename: Clarellen E
authors.initials: CE
authors.lastname: Spencer
authors.forename: Lisa
authors.initials: L
authors.lastname: Wang
authors.forename: Brenda L
authors.initials: BL
authors.lastname: Gallie
mesh_terms: D000328:Adult; D000818:Animals; D045744:Cell Line, Tumor; D002868:Chromosomal Proteins, Non-Histone / Q000096:biosynthesis / Q000235:genetics*; D002896:Chromosomes, Human, Pair 6 / Q000235:genetics*; D050699:E2F3 Transcription Factor / Q000096:biosynthesis / Q000235:genetics*; D018628:Gene Dosage; D020869:Gene Expression Profiling; D006801:Humans; D016547:Kinesins / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D015513:Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics*; D000075223:Poly-ADP-Ribose Binding Proteins; D012333:RNA, Messenger / Q000096:biosynthesis; D012160:Retina / Q000378:metabolism; D019572:Retinal Neoplasms / Q000235:genetics* / Q000378:metabolism; D012175:Retinoblastoma / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D002868:Chromosomal Proteins, Non-Histone; C084738:DEK protein, human; D050699:E2F3 Transcription Factor; C098319:E2F3 protein, human; C490840:E2f3 protein, mouse; C417670:KIF13A protein, human; D015513:Oncogene Proteins; D000075223:Poly-ADP-Ribose Binding Proteins; D012333:RNA, Messenger; D016547:Kinesins