Background.PRAME gene spontaneous expression is frequently observed in a cancer cell. The protein encoded by this gene increases the viability of tumour cell. NF-κB signalling pathway takes part in PRAME upregulation. It proposes, that stress conditions may increase the expression level of PRAME in the tumour cell and increase cell’s viability after it. We hypothesized that this phenomenon determines chemoresistance of PRAME-expressing cell, which can be overcome by NF-κB inhibitors, such as bortezomib.Materials and methods.We incubated A875 melanoma cells with cisplatin, bortezomib and dexamethasone, as well as with a mixture of cisplatin with bortezomib and cisplatin with dexamethasone within 24 hours. To assess the cytotoxicity of these combinations MTT-test was used. For evaluation of PRAME expression level, real-time polymerase chain reaction was used. All data were analyzed with Wilcoxon test for coupled samples.Results.It was found that cisplatin and dexamethasone increased an expression level of PRAME compared to control (p <0.03). The addition of dexamethasone to cisplatin reduced cytotoxic effect of cisplatin. Bortezomib has a cytotoxic effect, but it did not increase the activity of PRAME gene (p = 0.12). PRAME gene activity in cells incubated with a mixture of cisplatin and bortezomib was observed at a lower level in comparison with cells incubated with cisplatin (p = 0.0277).Conclusion.The results of experiments show that an increase of PRAME expression level reduces the sensitivity of melanoma cells to the cytotoxic effect of cisplatin. PRAME activity increases under stress conditions. Using of bortezomib can inhibit the growth of PRAME expression and makes the tumour cell more vulnerable to cytotoxic agents. On the other hand, dexamethasone may increase a resistance of PRAME-expressing cell to cytotoxic effects.
Intrоduction.Human antigen PRAME is preferentially expressed in a number of different tumor types and may be a potent target for anti-tumor immunotherapy.Purpose.To study anti-tumor action of immunogenic mix recombinant PRAME protein and adjuvant in mice with innate immunity.Materials and methods.C57BL/6 female mice were used for immunization with purified human recombinant protein PRAME. Human PRAME gene coding sequence was cloned in mammalian expressing vector pCEP4 and resulting plasmid was introduced in mouse melanoma B16F10 cells by transfection followed by RQ-PCR, Western blot and flow-cytometry analysis. Then stably PRAME-transfected melanoma cells were injected in mice.Results.The mouse melanoma B16F10 cells stably expressing human PRAME protein were obtained. We demonstrate the 10-fold decreased tumor volume in mice with melanoma B16F10 expressing human PRAME after preventive immunization series with recombinant PRAME protein. The tumor volume reducing was correlated with high titer (6.14 × 10 5) of anti-PRAME antibodies in mice sera.Conclusion.These data indicate that recombinant protein PRAME is immunogenic and may be a potent antigen for immunotherapuetics studies.
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