ABSTRACT
A wide range of human malignancies displays aberrant activation of Hedgehog (HH)/GLI signaling, including cancers of the skin, brain, gastrointestinal tract and hematopoietic system. Targeting oncogenic HH/GLI signaling with small molecule inhibitors of the essential pathway effector Smoothened (SMO) has shown remarkable therapeutic effects in patients with advanced and metastatic basal cell carcinoma. However, acquired and de novo resistance to SMO inhibitors poses severe limitations to the use of SMO antagonists and urgently calls for the identification of novel targets and compounds.Here we report on the identification of the Dual-Specificity-Tyrosine-Phosphorylation-Regulated Kinase 1B (DYRK1B) as critical positive regulator of HH/GLI signaling downstream of SMO. Genetic and chemical inhibition of DYRK1B in human and mouse cancer cells resulted in marked repression of HH signaling and GLI1 expression, respectively. Importantly, DYRK1B inhibition profoundly impaired GLI1 expression in both SMO-inhibitor sensitive and resistant settings. We further introduce a novel small molecule DYRK1B inhibitor, DYRKi, with suitable pharmacologic properties to impair SMO-dependent and SMO-independent oncogenic GLI activity. The results support the use of DYRK1B antagonists for the treatment of HH/GLI-associated cancers where SMO inhibitors fail to demonstrate therapeutic efficacy.
Subject(s)
Carcinoma, Basal Cell/pathology , Drug Resistance, Neoplasm , Hedgehog Proteins/metabolism , Pancreatic Neoplasms/pathology , Protein Serine-Threonine Kinases/metabolism , Protein-Tyrosine Kinases/metabolism , Smoothened Receptor/metabolism , Zinc Finger Protein GLI1/metabolism , Animals , Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Blotting, Western , Carcinoma, Basal Cell/drug therapy , Carcinoma, Basal Cell/genetics , Carcinoma, Basal Cell/metabolism , Cell Proliferation/drug effects , Cells, Cultured , Forkhead Transcription Factors/physiology , Hedgehog Proteins/antagonists & inhibitors , Hedgehog Proteins/genetics , Humans , Mice , Mice, Nude , NIH 3T3 Cells , Pancreatic Neoplasms/drug therapy , Pancreatic Neoplasms/genetics , Pancreatic Neoplasms/metabolism , Protein Serine-Threonine Kinases/antagonists & inhibitors , Protein Serine-Threonine Kinases/genetics , Protein-Tyrosine Kinases/antagonists & inhibitors , Protein-Tyrosine Kinases/genetics , RNA, Messenger/genetics , RNA, Small Interfering/genetics , Real-Time Polymerase Chain Reaction , Reverse Transcriptase Polymerase Chain Reaction , Skin Neoplasms/drug therapy , Skin Neoplasms/genetics , Skin Neoplasms/metabolism , Skin Neoplasms/pathology , Smoothened Receptor/antagonists & inhibitors , Smoothened Receptor/genetics , Xenograft Model Antitumor Assays , Zinc Finger Protein GLI1/antagonists & inhibitors , Zinc Finger Protein GLI1/genetics , Dyrk KinasesABSTRACT
Heat shock proteinâ 90 (Hsp90) is a significant target in the development of rational cancer therapy, due to its role at the crossroads of multiple signaling pathways associated with cell proliferation and viability. Here, a novel series of Hsp90 inhibitors containing a quinolein-2-one scaffold was synthesized and evaluated in cell proliferation assays. Results from these structure-activity relationships studies enabled identification of the simplified 3-aminoquinolein-2-one analogue 2 b (6BrCaQ), which manifests micromolar activity against a panel of cancer cell lines. The molecular signature of Hsp90 inhibition was assessed by depletion of standard known Hsp90 client proteins. Finally, processing and activation of caspases 7, 8, and 9, and the subsequent cleavage of PARP by 6BrCaQ, suggest stimulation of apoptosis through both extrinsic and intrinsic pathways.