Potential mechanism of lactate dehydrogenase A acetylation regulation to promote bortezomib resistance in multiple myeloma
Objective:To explore the potential mechanism by which the acetylation regulation of lactate dehy-drogenase A(LDHA)promotes bortezomib(BTZ)resistance in multiple myeloma(MM).Methods:The relation-ship between LDHA expression and bortezomib sensitivity was examined in myeloma patients.Myeloma cell lines resistant to BTZ were constructed to detect the expression of LDHA in resistant and sensitive strains.The cell proliferation of resistant and sensitive myeloma strains after BTZ treatment was detected by CCK8,and the apop-tosis rate of resistant and sensitive myeloma strains after BTZ treatment was examined by flow cytometry.Poten-tial post-translational modification sites for LDHA were predicted using the iHypoxia database,and common post-translational modifications were tested.In order to explore the upstream regulation mechanism of LDHA,the ex-pression of LDHA was detected after treating myeloma cells with different inhibitors.Results:The expression of LDHA in tumor tissues of MM patients was significantly higher than that of control,and both the level of LDHA protein and mRNA in BTZ-resistant patients were significantly higher than that in BTZ-sensitive patients.MM1.s-BR and NCI-H929-BR resistant cell lines induced by BTZ were successfully constructed.CCK8 showed that the survival rate of BTZ-resistant cell lines after BTZ treatment was higher than that of sensitive cell lines,while flow cytometry results showed that the apoptosis rate of BTZ-sensitive cell lines was higher than that of drug-re-sistant cell lines after treated with BTZ.The above results confirmed the successful construction of BTZ-resistant cell lines.Western blot results showed that the expression of LDHA in BTZ resistant cell lines was higher than that in wild-type cell lines.As predicted by the database,the common post-translational modification sites of LDHA were phosphorylation,acetylation and ubiquitination.The acetylation level of BTZ resistant cell lines was significantly lower than that of sensitive cell lines,but there was no significant difference in the degree of other post-translational modification between resistant and sensitive cell lines.Administration of trichostatin(TSA),a common inhibitor of histone deacetylase(HD AC)Ⅰ and Ⅱ,could decrease the level of LDHA and increase its acetylation level in BTZ resistant cell lines.TSA could overcome the resistance of MM1.s-BRto BTZ,but not the BTZ resistance of MM1.s LDH high BRwith high expression of LDHA.Conclusion:HDAC Ⅰ/Ⅱ may increase the level of LDHA by promoting its deacetylation and contribute to the resistance of MM to BTZ.
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