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Heat shock protein Hsp90, detected in the extracellular space and on the membrane of cells, plays an important role in cell motility, migration, invasion and metastasis of tumor cells. At present, the functional role and molecular mechanisms of Hsp90 binding to plasma membrane are not elucidated. Using isoform-specific antibodies against Hsp90, Hsp9α and Hsp90β, we showed that membrane-bound Hsp90α and Hsp90β play a significant role in migration of human fibrosarcoma (HT1080) and glioblastoma (A-172) cells in vitro. Disorders of sulfonation of cell heparan sulfates, cleavage of cell heparan. sulfates by heparinase I/III as well as treatment of cells with heparin lead to an abrupt reduction in the expression level of Hsp90 isoforms. Furthermore, heparin significantly inhibits tumor cell migration. The results obtained demonstrate that two isoforms of membrane-bound Hsp90 are involved in migration of tumor cells in vitro and that cell surface heparan sulfate proteoglycans play a pivotal role in the "anchoring" of Hsp90α and Hsp90β to the plasma membrane.

The effects of geldanamycin, which is known as inhibitor of heat shock protein 90 activities, on expression of several signal and heat shock proteins were studied by Western blot analysis in cultivated spleen lymphocytes isolated from male NMRI mice. It has been revealed that cultivating the cells with geldanamycin resulted in decrease in transcription factor NF-kappaB amount, as well as decrease in its phosphorylated form, pNF-kappaB, and lowering in its suppressor, IkappaB-alpha. Besides, cells cultivated with geldanamycin demonstrated significant decrease in the amount of protein kinase SAPK(JNK). The modifications in signal pathways, which had been induced by geldanamycin, pointed to direct influence of the antibiotics on cellular stress response to damaging impact. This assumption was examined with the model of cellular stress response induced by low-level laser radiation. It was proved that Hsp90-binding drug, geldanamycin, significantly decreased in vitro stress response to laser light via lowering the production of heat shock proteins, Hsp70 and Hsp25, both in irradiated lymphocytes and in theirs intracellular structures. These findings show the prospect for using of geldanamycin in various therapies that are compromised with objectionable side effects manifested as heightened stress response in immune cells.

The effect of in vitro exposure to low-power laser light with a power density of 0.2 mW/cm2 and a wavelength of 632.8 nm induced by helium-neon laser on the functional activity of macrophages and splenic lymphocytes was studied. If the exposure period did not exceed 60 sec, the stimulation in interleukin-2 (IL-2) and nitric oxide (NO) production, as well as an increase in the activity of natural killer cells were observed. The increase of irradiation dose by prolongation of the exposure duration up to 180 s induced a significant decrease in NO production and natural killer cell activity, but IL-2 production was not different from the control level. A remarkable decrease in interferon-gamma (IFN-gamma) production was observed following laser light exposure of cells for 60 or 180 s, whereas under lower doses (exposure for 5 or 30 sec) IFN-gamma production increased. Irradiation of isolated macrophages induced a significant stimulation of cellular tumor necrosis factor-alpha (TNF- alpha) production at all dboes used, and, what is more important, an enhancement in both TNF-a phaand interleukin-6 (IL-6) production was revealed as early as after a 5-s exposure. In this case, more prolonged exposure periods, 60 and 180 s, either did not induce changes in IL-6 production (in macrophages) or decreased IL-6 production (in lymphocytes). Thus, upon in vitro exposure of cells to extremely low-power laser light, a basic tendency was observed: short-term irradiation predominantly induced stimulation in secretory activity of cells, whereas prolongation of exposure mainly induced immunosuppression. The only exception to the rule was a change in interleukin-3 (IL-3) production, which decreased after short-time exposure, but, on the opposite, increased when the cells were exposed for 180 s. In addition, a high sensitivity to extremely low-power laser light was supported by expression of the inducible heat shock protein, Hsp70, the effect being observed at all doses used, including the exposure for 5 s. At the same time, expression of another heat shock protein, Hsp90, was somewhat reduced after irradiation of cells with laser light.