knk-437 and Chronic-Disease

This study aimed to assess the antitumour effects, molecular mechanisms of action, and potential synergy of ruxolitinib with sorafenib, KNK437, dasatinib, and perifosine, in Philadelphia-negative chronic myeloproliferative neoplasms (MPN). Cytotoxic and cytostatic effects of the different compounds were determined in the JAK2 V617F-positive cell lines, HEL and Ba/F3 (JAK2V617F EPOR) , and in primary mononuclear and bone marrow CD34-positive cells from 19 MPN patients. Ruxolitinib [50% inhibitory concentration (IC50 )(PV)  = 15 nmol/l], as well as sorafenib (IC50 PV=8μmol/l), KNK437 (IC50 PV=100μmol/l ), and perifosine (IC50 PV=15μmol/l ), were able to inhibit proliferation in cell line models and in primary cells from MPN patients. Dasatinib, KNK437, and sorafenib showed a strong synergistic effect in combination with ruxolitinib [combination index (CI)(PV)  < 0·3]. Western blot confirmed that ruxolitinib blocked ERK, and consequently STAT5 activation, sorafenib inhibited ERK, P38 and STAT5, dasatinib blocked SRC and STAT5, and KNK437 decreased the stability of the JAK2 protein, reducing its expression. Inhibiting JAK2-related proliferative pathways has the potential to inhibit cell proliferation in MPNs. Furthermore, the combination of ruxolitinib with inhibitors that target these pathways has a strong synergistic effect, which may be due to decreased activation of the common effector, STAT5.

Topics: Adult; Aged; Aged, 80 and over; Benzhydryl Compounds; Cell Proliferation; Cells, Cultured; Chronic Disease; Dasatinib; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Drug Synergism; Female; Humans; Janus Kinase 2; Janus Kinases; Male; Middle Aged; Myeloproliferative Disorders; Niacinamide; Nitriles; Phenylurea Compounds; Phosphorylcholine; Polycythemia Vera; Protein Kinase Inhibitors; Pyrazoles; Pyrimidines; Pyrrolidinones; Signal Transduction; Sorafenib; STAT5 Transcription Factor; Thiazoles; Thrombocythemia, Essential; Tumor Cells, Cultured

We investigated whether the attenuation of chronic thermotolerance by KNK437, a heat shock protein inhibitor, can modify the effect of thermal radiosensitization in mild temperature hyperthermia (MTH) combined with low dose-rate irradiation (LDRI).. The human lung adenocarcinoma cell line A549 was simultaneously exposed to LDRI with MTH at 41 degrees C and KNK437 at a dose of 100 microM. Cell survival was estimated by a clonogenic assay. Cell cycle change during treatment was analyzed by flow cytometry. Expression levels of the heat shock proteins hsp72, hsp27 and heat shock factor 1 (HSF-1) were measured by Western blotting.. KNK437 inhibited the expression of inducible hsp72 and hsp27, but produced no change in the mobility shift of HSF-1. The cytotoxicity of LDRI was enhanced by MTH. The survival curve for LDRI + MTH revealed no development of chronic thermotolerance up to 48 h. Simultaneous LDRI and KNK437 treatment also resulted in enhanced cell killing. The radiosensitizing effect of KNK437 was enhanced by simultaneous exposure of the cells to MTH. Flow cytometry analysis of cell cycle progression demonstrated marked G2 arrest and mild G1 arrest with LDRI alone, but mild G1 arrest with MTH alone, and mild G2-M, S-phase accumulation with KNK437 alone. The marked G2 arrest caused by LDRI was partially suppressed by the addition of MTH, and was also suppressed by KNK437 treatment.. Exposure of A549 cells to KNK437 caused inhibition of hsp72 and hsp27 expression. The addition of KNK437 increased not only thermosensitivity to MTH, but also radiosensitivity to LDRI. KNK437 also enhanced the MTH-induced radiosensitization under these experimental conditions.

Topics: Adaptation, Physiological; Adenocarcinoma; Benzhydryl Compounds; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cell Survival; Chronic Disease; Combined Modality Therapy; Dose-Response Relationship, Drug; Dose-Response Relationship, Radiation; Heat-Shock Proteins; Heat-Shock Response; Humans; Hypothermia; Lactams; Pyrrolidinones; Radiation Dosage; Radiation Tolerance; Temperature