TY - JOUR
T1 - hPaf1/PD2 interacts with OCT3/4 to promote self-renewal of ovarian cancer stem cells
AU - Karmakar, Saswati
AU - Seshacharyulu, Parthasarathy
AU - Lakshmanan, Imayavaramban
AU - Vaz, Arokia P.
AU - Chugh, Seema
AU - Sheinin, Yuri M.
AU - Mahapatra, Sidharth
AU - Batra, Surinder Kumar
AU - Palanimuthu Ponnusamy, Moorthy
N1 - Funding Information:
The authors acknowledge the invaluable technical support of Mrs. Kavita Mallya. We also want to acknowledge the confocal laser-scanning microscopy and flow cytometry core at UNMC for their help and support. The authors in this article were supported, in parts, by the following grants: National Institutes of Health (RO1 CA183459, TMEN U54CA163120, EDRN UO1 CA111294, SPORE P50CA127297 and K22 CA175260), Elsa U Pardee Foundation-2013 and the Nebraska Department of Health and Human Services LB595. In addition, Saswati Karmakar received University of Nebraska Medical Center (UNMC) Graduate Assistantship from Graduate Studies Office for 2016-2017.
PY - 2017
Y1 - 2017
N2 - 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.
AB - 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.
KW - CSC
KW - HPaf1/PD2
KW - OCT3/4
KW - Ovarian cancer
KW - Self-renewal
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UR - http://www.scopus.com/inward/citedby.url?scp=85014066886&partnerID=8YFLogxK
U2 - 10.18632/oncotarget.14775
DO - 10.18632/oncotarget.14775
M3 - Article
C2 - 28122356
AN - SCOPUS:85014066886
SN - 1949-2553
VL - 8
SP - 14806
EP - 14820
JO - Oncotarget
JF - Oncotarget
IS - 9
ER -