knk-437 and Adenocarcinoma

Cell surface nucleolin (NCL) plays fundamental roles in tumor angiogenesis. However, the mechanism underlying its surface translocation remains obscure. The present study discovered that heat shock cognate 70 (Hsc70) is essential in both the surface translocation and the angiogenic function of NCL.. We identified that Hsc70 interacted with NCL in endothelial cells via the peptide-binding domain of Hsc70 and the RNA-binding domain of NCL. Functional knockdown of Hsc70 remarkably inhibited the expression of surface NCL, which was rescued by wild-type Hsc70 rather than its truncations. Phosphorylation of NCL by either protein kinase C-ξ or casein kinase 2 mediated its interaction with Hsc70 and the surface expression. Hsc70 regulated NCL translocation via stabilizing NCL and enhancing its interaction with nonmuscle myosin heavy chain 9. Moreover, Hsc70 was associated with NCL-induced endothelial cell migration and tubule formation in vitro and angiogenesis in both matrigel plugs and xenograft tumors. Tissue array analysis revealed that the expression levels of NCL and Hsc70 were intimately correlated in human lung adenocarcinomas.. Our study demonstrates that Hsc70 is a prerequisite for the surface translocation and angiogenic function of NCL, which suggests strategies to target both Hsc70 and NCL for more effective antiangiogenic therapies.

Topics: Adenocarcinoma; Adenocarcinoma of Lung; Animals; Benzhydryl Compounds; Binding Sites; Carcinoma, Non-Small-Cell Lung; Casein Kinase II; Cell Line, Tumor; Cell Movement; HSC70 Heat-Shock Proteins; Human Umbilical Vein Endothelial Cells; Humans; Lung Neoplasms; Mice; Mice, Nude; Myosin Heavy Chains; Neovascularization, Pathologic; Neovascularization, Physiologic; Nucleolin; Phosphoproteins; Phosphorylation; Protein Interaction Domains and Motifs; Protein Interaction Mapping; Protein Kinase C-epsilon; Protein Stability; Protein Transport; Pyrrolidinones; RNA Interference; RNA-Binding Proteins; Tissue Array Analysis; Transfection; Xenograft Model Antitumor Assays

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