title: Identification of the DEAD box RNA helicase DDX3 as a therapeutic target in colorectal cancer.
abstract: Identifying druggable targets in the Wnt-signaling pathway can optimize colorectal cancer treatment. Recent studies have identified a member of the RNA helicase family DDX3 (DDX3X) as a multilevel activator of Wnt signaling in cells without activating mutations in the Wnt-signaling pathway. In this study, we evaluated whether DDX3 plays a role in the constitutively active Wnt pathway that drives colorectal cancer. We determined DDX3 expression levels in 303 colorectal cancers by immunohistochemistry. 39% of tumors overexpressed DDX3. High cytoplasmic DDX3 expression correlated with nuclear β-catenin expression, a marker of activated Wnt signaling. Functionally, we validated this finding in vitro and found that inhibition of DDX3 with siRNA resulted in reduced TCF4-reporter activity and lowered the mRNA expression levels of downstream TCF4-regulated genes. In addition, DDX3 knockdown in colorectal cancer cell lines reduced proliferation and caused a G1 arrest, supporting a potential oncogenic role of DDX3 in colorectal cancer. RK-33 is a small molecule inhibitor designed to bind to the ATP-binding site of DDX3. Treatment of colorectal cancer cell lines and patient-derived 3D cultures with RK-33 inhibited growth and promoted cell death with IC50 values ranging from 2.5 to 8 μM. The highest RK-33 sensitivity was observed in tumors with wild-type APC-status and a mutation in CTNNB1. Based on these results, we conclude that DDX3 has an oncogenic role in colorectal cancer. Inhibition of DDX3 with the small molecule inhibitor RK-33 causes inhibition of Wnt signaling and may therefore be a promising future treatment strategy for a subset of colorectal cancers.
authors: Department of Radiology and Radiological Science, Johns Hopkins University, School of Medicine, Baltimore, MD, USA.|Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors: Marise R
authors: MR
authors: Heerma van Voss
authors: Department of Radiology and Radiological Science, Johns Hopkins University, School of Medicine, Baltimore, MD, USA.
authors: Farhad
authors: F
authors: Vesuna
authors: Department of Surgery, University Medical Center Utrecht, Utrecht, The Netherlands.
authors: Kari
authors: K
authors: Trumpi
authors: Department of Radiology and Radiological Science, Johns Hopkins University, School of Medicine, Baltimore, MD, USA.
authors: Justin
authors: J
authors: Brilliant
authors: Wilmer Eye Institute, Johns Hopkins University, School of Medicine, Baltimore, MD, USA.
authors: Cynthia
authors: C
authors: Berlinicke
authors: Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors: Wendy
authors: W
authors: de Leng
authors: Department of Surgery, University Medical Center Utrecht, Utrecht, The Netherlands.
authors: Onno
authors: O
authors: Kranenburg
authors: Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors: G Johan
authors: GJ
authors: Offerhaus
authors: Institute of Pathology, Paderborn, Germany.
authors: Horst
authors: H
authors: Bürger
authors: Department of Internal Medicine, University Medical Center Utrecht, Utrecht, The Netherlands.
authors: Elsken
authors: E
authors: van der Wall
authors: Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors: Paul J
authors: PJ
authors: van Diest
authors: Department of Radiology and Radiological Science, Johns Hopkins University, School of Medicine, Baltimore, MD, USA.|Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands.|Department of Oncology, Johns Hopkins University, School of Medicine, Baltimore, MD, USA.
authors: Venu
authors: V
authors: Raman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001381:Azepines / Q000494:pharmacology; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism; D053487:DEAD-box RNA Helicases / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D015151:Immunoblotting; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D058990:Molecular Targeted Therapy / Q000379:methods; D009154:Mutation; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000073940:Transcription Factor 4; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D060449:Wnt Signaling Pathway / Q000187:drug effects / Q000235:genetics*; D051176:beta Catenin / Q000235:genetics* / Q000378:metabolism
chemical_list: C000603512:3,7-dihydro-3,7-bis((4-methoxyphenyl)methyl)-2H-diimidazo(4,5-d:4',5'-f)(1,3)diazepin-2-one; D001381:Azepines; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D007093:Imidazoles; C532096:TCF4 protein, human; D000073940:Transcription Factor 4; D014157:Transcription Factors; D051176:beta Catenin; C119332:DDX3X protein, human; C506749:Ddx5 protein, human; D053487:DEAD-box RNA Helicases
keywords: DEAD-box RNA helicases; Wnt signaling; colorectal cancer; small molecule inhibitors; β-catenin