title: hPaf1/PD2 interacts with OCT3/4 to promote self-renewal of ovarian cancer stem cells.
abstract: Cancer stem cells (CSCs), which mediate drug resistance and disease recurrence in several cancers, are therapeutically relevant to ovarian cancer (OC), wherein approximately 80% of patients manifest with tumor recurrence. While there are several markers for ovarian CSCs (OCSCs), the mechanism for their self-renewal maintenance by unique driver/markers is poorly understood. Here, we evaluated the role of hPaf1/PD2, a core component of RNA Polymerase II-Associated Factor (PAF) complex, in self-renewal of OCSCs through marker and functional analyses, including CRISPR/Cas9-silencing of hPaf1/PD2 in OCSCs and provided a possible mechanism for maintenance of OCSCs. Expression of hPaf1/PD2 showed moderate to intense staining in 32.4% of human OC tissues, whereas 67.6% demonstrated basal expression by immunohistochemistry analysis, implying that the minor proportion of cells overexpressing hPaf1/PD2 could be putative OCSCs. Isolated OCSCs showed higher expression of hPaf1/PD2 along with established CSC and self-renewal markers. Knockdown of hPaf1/PD2 in OCSCs resulted in a significant downregulation of CSC and self-renewal markers, and impairment of in vitro tumor sphere (P < 0.05) and colony formation (P = 0.013). Co-immunoprecipitation revealed that OCT3/4 specifically interacts with hPaf1/PD2, and not with other PAF components (Ctr9, Leo1, Parafibromin) in OCSCs, suggesting a complex-independent role for hPaf1/PD2 in OCSC maintenance. Moreover, there was a significant overexpression and co-localization of hPaf1/PD2 with OCT3/4 in OC tissues compared to normal ovary tissues. Our results indicate that hPaf1/PD2 is overexpressed in OCSCs and maintains the self-renewal of OCSCs through its interaction with OCT3/4; thus, hPaf1/PD2 may be a potential therapeutic target to overcome tumor relapse in OC.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA.
authors.forename: Saswati
authors.initials: S
authors.lastname: Karmakar
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA.
authors.forename: Parthasarathy
authors.initials: P
authors.lastname: Seshacharyulu
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA.
authors.forename: Imayavaramban
authors.initials: I
authors.lastname: Lakshmanan
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA.
authors.forename: Arokia P
authors.initials: AP
authors.lastname: Vaz
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA.
authors.forename: Seema
authors.initials: S
authors.lastname: Chugh
authors.affiliation: Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, USA.
authors.forename: Yuri M
authors.initials: YM
authors.lastname: Sheinin
authors.affiliation: Department of Pediatrics, University of Nebraska Medical Center, Omaha, NE, USA.
authors.forename: Sidharth
authors.initials: S
authors.lastname: Mahapatra
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA.|Fred and Pamela Buffett Cancer Center, Eppley Institute for Research in Cancer and Allied Disease, University of Nebraska Medical Center, Omaha, NE, USA.
authors.forename: Surinder K
authors.initials: SK
authors.lastname: Batra
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA.|Fred and Pamela Buffett Cancer Center, Eppley Institute for Research in Cancer and Allied Disease, University of Nebraska Medical Center, Omaha, NE, USA.
authors.forename: Moorthy P
authors.initials: MP
authors.lastname: Ponnusamy
mesh_terms: D064113:CRISPR-Cas Systems; D049109:Cell Proliferation; D005260:Female; D006801:Humans; D009367:Neoplasm Staging; D014411:Neoplastic Stem Cells / Q000378:metabolism / Q000473:pathology*; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D050814:Octamer Transcription Factor-3 / Q000235:genetics / Q000378:metabolism*; D010051:Ovarian Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D011379:Prognosis; D014157:Transcription Factors; D014407:Tumor Cells, Cultured
chemical_list: D009687:Nuclear Proteins; D050814:Octamer Transcription Factor-3; C501972:PAF1 protein, human; C494173:POU5F1 protein, human; D014157:Transcription Factors
keywords: CSC; OCT3/4; hPaf1/PD2; ovarian cancer; self-renewal