Extracellular heat shock protein 70 mediates heat stress-induced epidermal growth factor receptor transactivation in A431 carcinoma cells

The initial steps of heat stress in A431 cells were previously characterized by ligand-independent EGFR transactivation via an unknown mechanism and concomitant secretion of Hsp70. In this work we demonstrate that the depletion of Hsp70 from the conditioned medium of heated cells abolishes EGFR transactivation indicating that secreted Hsp70 is essential for EGFR transactivation during heat shock. This notion is supported by the findings that purified Hsp70 can induce EGFR transactivation and the activation of EGFR-dependent signaling pathways. Both heat stress and pure Hsp70 stimulate activation of TLR2/4 and their association with EGFR. These results suggest that the secreted Hsp70 mediates the cross-communication of TLR and EGFR signaling systems in A431 cells.     

Selection for a decrease in metastatic potential in a cell population of transplantable rat rhabdomyosarcoma RA-2

The method of individual cloning was used for checking the reduction of metastatic potential (MP) in cell population of highly malignant rhabdomyosarcoma RA-2. In the course of 15 selection cycles MP was lowered by 10-15 times. These data enabled us to consider the MP value as a quantitative character of malignant cells with low heritability (the mean value of realized heritability coefficient is equal to 0.18).     

Effect of cobalt and copper complexes with o-phenanthroline on the respiratory activity of mitochondria]

The effects of cobalt and copper complexes with o-phenantroline on the respiratory activity of mitochondria from pea sprouts and submitochondrial particles from bovine heart and on the oxidative phosphorylation in mitochondria were studied. The catalytic activity of the complexes in several components of the respiratory chain autooxidation reactions was investigated. It was shown that the bis (o-phenantroline) cobalt (II) chloride complex is more active in exidation of NADH. The tris (o-phenantroline) cobolt (III) perchlorate complex stimulates the respiratory activity of mitochondria and submitochondrial particles. Possible localization of the effect of this complex was postulated. The (o-phenantroline) copper chloride complex completely inhibits the succinate-dependent respiration of submitochondrial particles and causes disturbances in oxidative phosphorylation of mitochondria.