Research at molecular and gene level on enhancement mechanisms combined with irradiation and hyperthermia in culture cell lines

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1 Relationship between radiation/or heating induced cell cycle disturbance and gene expression of 14-3-3a, cdc2 and 25 were studied in human cancer cells lines. When cells were heated for 20 to 40 min. at 45 degree, G2-block(G2 cells accumulation) were induced. At that time, decrease of cdc2 and increase of cdc25-P, was observed. When cells were released from G2-block, it was observed increase of cdc2 and decrease of cdc25-P.2 We established the method of synchronization of culture human cancer cells. Fractions of S phase cells in population reached about 90 percent 13 hours after stimulation of serum. It was suggested that this method is useful for experiments to determine gene expression after cells were exposed to several conditions.3 Using a pEYFP-Nuc vector, which contains nucleic acid sequences of a nuclear localization signal, we established a Jurkat-YN cell line that expressed enhanced yellow fluorescent protein (EYFP) in the nucleus. The nuclear forms visualized by EYFP were a … More lmost equal in quality to those visualized by SYTO59, a nucleic acid stain for living cells. Three-dimensional deformities in the nuclear form were observed during apoptosis before chromatin condensation became apparent, indicating these deformities are characteristic morphological changes of the early stage of apoptosis.4 We report here an analysis of the mechanisms of the inhibition by KNK437 in 2 human oral squamous cell carcinma cell lines whose heat sensitivities are different (HSC4; heat-resistant and KB; heat-sensitive) with a view to identifying which if any HSPs are targeted for KNK437. Combined administration of KNK437 to the medium after heat shock specifically inhibited the induction of HSPs including HSP27, HSP40, HSP70 and HSP90 in time dependence. The hyperthermic treatment combined with heating and KNK437 produced supra-reductive effects (i.e. HSP27 and HSP90 in HSC4, HSP27, HSP40 and HSP90 in KB). Careful examination of the ability of KNK437 to inhibit the induction of various HSPs may therefore be valuable in future attempts to improve the efficacy of oral cancer hyperthermic therapy.5 Heat-induced changes in histone H3 methylation especially for H3-Lys4 and H3-Lys9 methylation in combination with KNK-437 have been studied in two human oral cancer cell lines such as HSC4 and KB,. Heating of HSC4 cells at 45C for 20 min and KB cells for 3 min gradually increased H3-Lys4 and H3-Lys9 methylation. Treatment of both cells with KNK-437 before or after heat-treatment inhibited methylation of H3-Lys4. Our results indicate a possibility of alteration in histone structure by heat treatment as a result of change in the methylation of H3 histone. Use of KNK-437, an inhibitor of HSPs gene expression, inhibited methylation of H3 Lys4. From these results, there exist some mechanism to regulate the expressions of genes in DNA by heat treatment. Less