title: A Synthetic Lethality Screen Using a Focused siRNA Library to Identify Sensitizers to Dasatinib Therapy for the Treatment of Epithelial Ovarian Cancer.
abstract: Molecular targeted therapies have been the focus of recent clinical trials for the treatment of patients with recurrent epithelial ovarian cancer (EOC). The majority have not fared well as monotherapies for improving survival of these patients. Poor bioavailability, lack of predictive biomarkers, and the presence of multiple survival pathways can all diminish the success of a targeted agent. Dasatinib is a tyrosine kinase inhibitor of the Src-family kinases (SFK) and in preclinical studies shown to have substantial activity in EOC. However, when evaluated in a phase 2 clinical trial for patients with recurrent or persistent EOC, it was found to have minimal activity. We hypothesized that synthetic lethality screens performed using a cogently designed siRNA library would identify second-site molecular targets that could synergize with SFK inhibition and improve dasatinib efficacy. Using a systematic approach, we performed primary siRNA screening using a library focused on 638 genes corresponding to a network centered on EGFR, HER2, and the SFK-scaffolding proteins BCAR1, NEDD9, and EFS to screen EOC cells in combination with dasatinib. We followed up with validation studies including deconvolution screening, quantitative PCR to confirm effective gene silencing, correlation of gene expression with dasatinib sensitivity, and assessment of the clinical relevance of hits using TCGA ovarian cancer data. A refined list of five candidates (CSNK2A1, DAG1, GRB2, PRKCE, and VAV1) was identified as showing the greatest potential for improving sensitivity to dasatinib in EOC. Of these, CSNK2A1, which codes for the catalytic alpha subunit of protein kinase CK2, was selected for additional evaluation. Synergistic activity of the clinically relevant inhibitor of CK2, CX-4945, with dasatinib in reducing cell proliferation and increasing apoptosis was observed across multiple EOC cell lines. This overall approach to improving drug efficacy can be applied to other targeted agents that have similarly shown poor clinical activity.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, Kansas, United States of America.|University of Kansas Cancer Center, Kansas City, Kansas, United States of America.
authors.forename: Harsh B
authors.initials: HB
authors.lastname: Pathak
authors.affiliation: Biostatistics and Bioinformatics Facility, Fox Chase Cancer Center, Philadelphia, Pennsylvania, United States of America.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States of America.
authors.forename: Geetika
authors.initials: G
authors.lastname: Sethi
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, Kansas, United States of America.
authors.forename: Jeff
authors.initials: J
authors.lastname: Hirst
authors.affiliation: Department of Gynecologic Medical Oncology, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America.
authors.forename: Russell J
authors.initials: RJ
authors.lastname: Schilder
authors.affiliation: Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania, United States of America.
authors.forename: Erica A
authors.initials: EA
authors.lastname: Golemis
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, Kansas, United States of America.|University of Kansas Cancer Center, Kansas City, Kansas, United States of America.
authors.forename: Andrew K
authors.initials: AK
authors.lastname: Godwin
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D000971:Antineoplastic Combined Chemotherapy Protocols; D017209:Apoptosis; D000077216:Carcinoma, Ovarian Epithelial; D047390:Casein Kinase II / Q000037:antagonists & inhibitors; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D000069439:Dasatinib / Q000494:pharmacology*; D004357:Drug Synergism; D049030:Dystroglycans / Q000037:antagonists & inhibitors; D005260:Female; D051380:GRB2 Adaptor Protein / Q000037:antagonists & inhibitors; D015723:Gene Library; D006801:Humans; D009287:Naphthyridines / Q000494:pharmacology*; D009375:Neoplasms, Glandular and Epithelial / Q000188:drug therapy* / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D010619:Phenazines; D051744:Protein Kinase C-epsilon / Q000037:antagonists & inhibitors; D051567:Proto-Oncogene Proteins c-vav / Q000037:antagonists & inhibitors; D034741:RNA, Small Interfering / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; C483081:DAG1 protein, human; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; D009287:Naphthyridines; D010619:Phenazines; D051567:Proto-Oncogene Proteins c-vav; D034741:RNA, Small Interfering; C496618:VAV1 protein, human; D049030:Dystroglycans; C555142:silmitasertib; C570325:CSNK2A1 protein, human; D047390:Casein Kinase II; C497255:PRKCE protein, human; D051744:Protein Kinase C-epsilon; D000069439:Dasatinib