TY - JOUR
T1 - Targeting Notch signaling as a novel therapy for retinoblastoma
AU - Asnaghi, Laura
AU - Tripathy, Arushi
AU - Yang, Qian
AU - Kaur, Harpreet
AU - Hanaford, Allison
AU - Yu, Wayne
AU - Eberhart, Charles G.
N1 - Funding Information:
We thank Antoinette Price for her skillful technical assistance. This study was supported by the Pediatric Ophthalmology Career-Starter Research Grant funded by the Knights Templar Eye Foundation, Inc. (to L.A.). Quality assessment of the RNA samples and microarray analysis were conducted at The Sidney Kimmel Cancer Center Microarray Core Facility at the Johns Hopkins University, supported by NIH grant P30 CA006973 entitled Regional Oncology Research Center.
PY - 2016
Y1 - 2016
N2 - Retinoblastoma is the most common intraocular malignancy of childhood. Notch plays a key role in retinal cells from which retinoblastomas arise, and we therefore studied the role of Notch signaling in promoting retinoblastoma proliferation. Moderate or strong nuclear expression of Hes1 was found in 10 of 11 human retinoblastoma samples analyzed immunohistochemically, supporting a role for Notch in retinoblastoma growth. Notch pathway components were present in WERI Rb1 and Y79 retinoblastoma lines, with Jag2 and DLL4 more highly expressed than other ligands, and Notch1 and Notch2 more abundant than Notch3. The cleaved/active form of Notch1 was detectable in both lines. Inhibition of the pathway, achieved using a γ-secretase inhibitor (GSI) or by downregulating Jag2, DLL4 or CBF1 using short hairpin RNA, potently reduced growth, proliferation and clonogenicity in both lines. Upregulation of CXCR4 and CXCR7 and downregulation of PI3KC2β were identified by microarray upon Jag2 suppression. The functional importance of PI3KC2β was confirmed using shRNA. Synergy was found by combining GSI with Melphalan at their IC50. These findings indicate that Notch pathway is active in WERI Rb1 and Y79, and in most human retinoblastoma samples, and suggest that Notch antagonists may represent a new approach to more effectively treat retinoblastoma.
AB - Retinoblastoma is the most common intraocular malignancy of childhood. Notch plays a key role in retinal cells from which retinoblastomas arise, and we therefore studied the role of Notch signaling in promoting retinoblastoma proliferation. Moderate or strong nuclear expression of Hes1 was found in 10 of 11 human retinoblastoma samples analyzed immunohistochemically, supporting a role for Notch in retinoblastoma growth. Notch pathway components were present in WERI Rb1 and Y79 retinoblastoma lines, with Jag2 and DLL4 more highly expressed than other ligands, and Notch1 and Notch2 more abundant than Notch3. The cleaved/active form of Notch1 was detectable in both lines. Inhibition of the pathway, achieved using a γ-secretase inhibitor (GSI) or by downregulating Jag2, DLL4 or CBF1 using short hairpin RNA, potently reduced growth, proliferation and clonogenicity in both lines. Upregulation of CXCR4 and CXCR7 and downregulation of PI3KC2β were identified by microarray upon Jag2 suppression. The functional importance of PI3KC2β was confirmed using shRNA. Synergy was found by combining GSI with Melphalan at their IC50. These findings indicate that Notch pathway is active in WERI Rb1 and Y79, and in most human retinoblastoma samples, and suggest that Notch antagonists may represent a new approach to more effectively treat retinoblastoma.
KW - Melphalan
KW - Notch
KW - Proliferation
KW - Retinoblastoma
KW - γ-secretase inhibitors
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U2 - 10.18632/oncotarget.12142
DO - 10.18632/oncotarget.12142
M3 - Article
C2 - 27661116
AN - SCOPUS:84994378374
SN - 1949-2553
VL - 7
SP - 70028
EP - 70044
JO - Oncotarget
JF - Oncotarget
IS - 43
ER -