title: Expression of OCT4 pseudogenes in human tumours: lessons from glioma and breast carcinoma.
abstract: The POU family transcription factor OCT4 is required for maintaining the pluripotency of embryonic stem cells and for generating induced pluripotent stem cells. Although OCT4 is clearly shown to be expressed in some pluripotent germ cell tumours, its expression in human somatic tumours remains controversial. Some studies have shown that OCT4 is expressed in adult stem cells, somatic cancers and, further, cancer stem cells, while other studies failed to make such an observation. It is thus important to ascertain whether OCT4 is expressed in human somatic tumours. By using RT-PCR and sequencing analysis, three OCT4 pseudogenes, viz. OCT4-pg1, OCT4-pg3 and OCT4-pg4 but excluding the OCT4 gene, were found to be expressed in two types of human solid tumours, glioma and breast carcinoma, from which cancer stem cells had earlier been isolated. The protein expression of these pseudogenes was further demonstrated by immunochemistry and western blotting. Along with this, it was shown that OCT4 pseudogenes lacked OCT4-like activities. The expression of OCT4 splicing variant and various pseudogenes at both the mRNA and protein levels in human somatic tumours might call into question the reliability of the results regarding OCT4 expression and function in tumourigenesis. Hence, in investigations of OCT4 expression in cancers and stem cells, different approaches with appropriate controls would be desirable to exclude possibility of false-positive results.
authors.affiliation: Key Laboratory of the Ministry of Education for Experimental Teratology, Department of Histology and Embryology, Shandong University School of Medicine, 44 Wenhua Xi Road, Jinan, Shandong, People's Republic of China.
authors.forename: Shidou
authors.initials: S
authors.lastname: Zhao
authors.forename: Qiuhuan
authors.initials: Q
authors.lastname: Yuan
authors.forename: Hongbo
authors.initials: H
authors.lastname: Hao
authors.forename: Yuji
authors.initials: Y
authors.lastname: Guo
authors.forename: Shangming
authors.initials: S
authors.lastname: Liu
authors.forename: Yanmin
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jianli
authors.initials: J
authors.lastname: Wang
authors.forename: Huijuan
authors.initials: H
authors.lastname: Liu
authors.forename: Fuwu
authors.initials: F
authors.lastname: Wang
authors.forename: Kai
authors.initials: K
authors.lastname: Liu
authors.forename: Eng-Ang
authors.initials: EA
authors.lastname: Ling
authors.forename: Aijun
authors.initials: A
authors.lastname: Hao
mesh_terms: D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D001483:Base Sequence; D001932:Brain Neoplasms / Q000235:genetics* / Q000378:metabolism; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism; D005260:Female; D052138:Genes, Neoplasm; D005910:Glioma / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008875:Middle Aged; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics; D050814:Octamer Transcription Factor-3 / Q000096:biosynthesis / Q000235:genetics*; D011544:Pseudogenes; D012334:RNA, Neoplasm / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D016415:Sequence Alignment; D014407:Tumor Cells, Cultured; D055815:Young Adult
chemical_list: D009363:Neoplasm Proteins; D050814:Octamer Transcription Factor-3; C494173:POU5F1 protein, human; D012334:RNA, Neoplasm