Background. TERT oncogene rearrangement with transcriptional super-enhancers leads to substantial TERT
over-expression and neuroblastoma in high-risk neuroblastoma patients. Telomerase inhibitors show little
anticancer effects and cause life-threatening side effects in childhood brain cancer patients in clinical trials.
The transcriptional kinases CDK7 and CDK9 play critical roles in super-enhancer-associated oncogene
transcriptional initiation, pause release and elongation respectively, and CKIa induce p53 protein degradation.
The CDK7/CDK9/CKIa co-inhibitor A51 suppresses super-enhancer-associated oncogene expression and
activates p53 protein expression, resulting in leukemia regression in mice with no toxicity to normal tissues.
Preliminary Data. We have found that CDK7/CDK9/CKIa co-knockdown with shRNAs or treatment with the
CDK7/CDK9/CKIa co-inhibitor A51 considerably reduced TERT gene expression and MDM2 protein
expression, activated p53 protein expression, and induced substantial apoptosis in TERT oncogene-
rearranged neuroblastoma, but not normal cells. Analysis of a RNA sequencing gene expression-patient
prognosis dataset from 493 neuroblastoma patients, showed that high levels of CDK7 gene expression in
human tumor tissues positively correlated with high levels of TERT gene expression, and that high levels of
CDK7 and CKIa expression in human neuroblastoma tissues correlated with poor patient prognosis.
Specific Aims. (1) To identify the critical roles of CDK7 and CDK9 in inducing TERT gene transcriptional
initiation, elongation and over-expression and CKIa in inducing p53 protein degradation in TERT-rearranged
neuroblastoma cells; (2) To identify the critical roles of CDK7, CDK9 and CKIa in TERT-rearranged
neuroblastoma cell proliferation and survival in vitro and tumor progression in vivo; (3) To define the anticancer
efficacy of the CDK7/CDK9/CKIa co-inhibitor A51 against TERT-rearranged neuroblastoma in vitro and in vivo.
Outcomes and Significance. We hope to demonstrate that CDK7 and CDK9 co-operatively induce TERT
gene transcriptional initiation, pause release, elongation and over-expression, and CKIa induces p53 protein
degradation; that CDK7, CDK9 and CKIa co-operatively induce TERT-rearranged neuroblastoma cell
proliferation and survival in vitro and tumor progression in vivo; and that the CDK7/CDK9/CKIa co-inhibitor A51
efficiently blocks TERT gene transcriptional initiation, pause release, elongation and expression, activates p53
protein expression, induces neuroblastoma cell apoptosis in vitro, and blocks tumor progression and causes
tumor regression in mice xenografted with TERT-rearranged neuroblastoma cell lines or patient-derived
neuroblastoma tissues. As A51 is currently in clinical trials in leukemia patients, completion of this project will
provide the vital evidence for clinical trials of A51 therapy in patients with TERT gene-rearranged
neuroblastoma, against which no targeted therapy is now available for, or has ever be tested in, clinical trials.