title: Janus kinase inhibitor INCB20 has antiproliferative and apoptotic effects on human myeloma cells in vitro and in vivo.
abstract: Protein tyrosine kinases of the Janus kinase (JAK) family are associated with many cytokine receptors, which, on ligand binding, regulate important cellular functions such as proliferation, survival, and differentiation. In multiple myeloma, JAKs may be persistently activated due to a constant stimulation by interleukin (IL)-6, which is produced in the bone marrow environment. INCB20 is a synthetic molecule that potently inhibits all members of the JAK family with a 100- to 1,000-fold selectivity for JAKs over >70 other kinases. Treatment of multiple myeloma cell lines and patient tumor cells with INCB20 resulted in a significant and dose-dependent inhibition of spontaneous as well as IL-6-induced cell growth. Importantly, multiple myeloma cell growth was inhibited in the presence of bone marrow stromal cells. The IL-6 dependent cell line INA-6 was particularly sensitive to the drug (IC50<1 micromol/L). Growth suppression of INA-6 correlated with an increase in the percentage of apoptotic cells and inhibition of signal transducer and activator of transcription 3 phosphorylation. INCB20 also abrogated the protective effect of IL-6 against dexamethasone by blocking phosphorylation of SHP-2 and AKT. In contrast, AKT phosphorylation induced by insulin-like growth factor-I remained unchanged, showing selectivity of the compound. In a s.c. severe combined immunodeficient mouse model with INA-6, INCB20 significantly delayed INA-6 tumor growth. Our studies show that disruption of JAKs and downstream signaling pathways may both inhibit multiple myeloma cell growth and survival and overcome cytokine-mediated drug resistance, thereby providing the preclinical rationale for the use of JAK inhibitors as a novel therapeutic approach in multiple myeloma.
authors.affiliation: Jerome Lipper Multiple Myeloma Center, Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, 44 Binney Street, Boston, MA 02115, USA.
authors.forename: Renate
authors.initials: R
authors.lastname: Burger
authors.forename: Steven
authors.initials: S
authors.lastname: Le Gouill
authors.forename: Yu-Tzu
authors.initials: YT
authors.lastname: Tai
authors.forename: Reshma
authors.initials: R
authors.lastname: Shringarpure
authors.forename: Pierfrancesco
authors.initials: P
authors.lastname: Tassone
authors.forename: Paola
authors.initials: P
authors.lastname: Neri
authors.forename: Klaus
authors.initials: K
authors.lastname: Podar
authors.forename: Laurence
authors.initials: L
authors.lastname: Catley
authors.forename: Teru
authors.initials: T
authors.lastname: Hideshima
authors.forename: Dharminder
authors.initials: D
authors.lastname: Chauhan
authors.forename: Eian
authors.initials: E
authors.lastname: Caulder
authors.forename: Claire L
authors.initials: CL
authors.lastname: Neilan
authors.forename: Kris
authors.initials: K
authors.lastname: Vaddi
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.forename: Martin
authors.initials: M
authors.lastname: Gramatzki
authors.forename: Jordan S
authors.initials: JS
authors.lastname: Fridman
authors.forename: Kenneth C
authors.initials: KC
authors.lastname: Anderson
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects*; D001854:Bone Marrow Cells / Q000187:drug effects / Q000201:enzymology; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D018920:Coculture Techniques; D019610:Cytoprotection / Q000187:drug effects; D003907:Dexamethasone / Q000494:pharmacology; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D053612:Janus Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D051379:Mice; D009101:Multiple Myeloma / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology*; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D050796:STAT3 Transcription Factor / Q000378:metabolism; D017154:Stromal Cells / Q000187:drug effects / Q000201:enzymology; D013379:Substrate Specificity; D015996:Survival Rate; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D015850:Interleukin-6; D047428:Protein Kinase Inhibitors; D050796:STAT3 Transcription Factor; D003907:Dexamethasone; D053612:Janus Kinases