Background:Adult patients with T-cell lymphoblastic lymphoma(T-LBL)are treated with high-intensity chemotherapy regimens,but the response rate is still unsatisfactory because of frequent drug resistance.We aimed to in...Background:Adult patients with T-cell lymphoblastic lymphoma(T-LBL)are treated with high-intensity chemotherapy regimens,but the response rate is still unsatisfactory because of frequent drug resistance.We aimed to investigate the potential mechanisms of drug resistance in adults with T-LBL.Methods:Gene expression microarray was used to identify differential mRNA expression profiles between chemotherapy-resistant and chemotherapy-sensitive adult T-LBL tissues.Real-time PCR and immunohistochemistry were performed to detect the expression of bromodomain-containing protein 2(BRD2)and c-Myc in fresh-frozen T-LBL tissues from 85 adult patients.The Ras pull-down assay was performed to monitor Ras activation.Chromatin immunoprecipitation assays were used to analyze the binding of E2F transcription factor 1(E2F1)/BRD2 to the RAS guanyl releasing protein 1(RasGRP1)promoter region.The drug resistance effect and mechanism of BRD2 were determined by both in vivo and in vitro studies.Results:A total of 86 chemotherapy resistance-related genes in adult T-LBL were identified by gene expression microarray.Among them,BRD2 was upregulated in chemotherapy-resistant adult T-LBL tissues and associated with worse progressionfree survival and overall survival of 85 adult T-LBL patients.Furthermore,BRD2 suppressed doxorubicin(Dox)-induced cell apoptosis both in vitro and in vivo.The activation of RasGRP1/Ras/ERK signaling might contribute to the Dox resistance effect of BRD2.Besides,OTX015,a bromodomain and extra-terminal(BET)inhibitor,reversed the Dox resistance effect of BRD2.Patient-derived tumor xenograft demonstrated that the sequential use of OTX015 after Dox showed superior therapeutic effects.Conclusions:Our data showed that BRD2 promotes drug resistance in adult T-LBL through the RasGRP1/Ras/ERK signaling pathway.Targeting BRD2 may be a novel strategy to improve the therapeutic efficacy and prolong survival of adults with TLBL.展开更多
基金supported by the grants from National Key R&D Program of China(2017YFC1309001 and 2016YFC1302305)National Natural Science Foundation of China(81603137,81672686,and 81973384)Special Support Program of Sun Yat-sen University Cancer Center(PT19020401).
文摘Background:Adult patients with T-cell lymphoblastic lymphoma(T-LBL)are treated with high-intensity chemotherapy regimens,but the response rate is still unsatisfactory because of frequent drug resistance.We aimed to investigate the potential mechanisms of drug resistance in adults with T-LBL.Methods:Gene expression microarray was used to identify differential mRNA expression profiles between chemotherapy-resistant and chemotherapy-sensitive adult T-LBL tissues.Real-time PCR and immunohistochemistry were performed to detect the expression of bromodomain-containing protein 2(BRD2)and c-Myc in fresh-frozen T-LBL tissues from 85 adult patients.The Ras pull-down assay was performed to monitor Ras activation.Chromatin immunoprecipitation assays were used to analyze the binding of E2F transcription factor 1(E2F1)/BRD2 to the RAS guanyl releasing protein 1(RasGRP1)promoter region.The drug resistance effect and mechanism of BRD2 were determined by both in vivo and in vitro studies.Results:A total of 86 chemotherapy resistance-related genes in adult T-LBL were identified by gene expression microarray.Among them,BRD2 was upregulated in chemotherapy-resistant adult T-LBL tissues and associated with worse progressionfree survival and overall survival of 85 adult T-LBL patients.Furthermore,BRD2 suppressed doxorubicin(Dox)-induced cell apoptosis both in vitro and in vivo.The activation of RasGRP1/Ras/ERK signaling might contribute to the Dox resistance effect of BRD2.Besides,OTX015,a bromodomain and extra-terminal(BET)inhibitor,reversed the Dox resistance effect of BRD2.Patient-derived tumor xenograft demonstrated that the sequential use of OTX015 after Dox showed superior therapeutic effects.Conclusions:Our data showed that BRD2 promotes drug resistance in adult T-LBL through the RasGRP1/Ras/ERK signaling pathway.Targeting BRD2 may be a novel strategy to improve the therapeutic efficacy and prolong survival of adults with TLBL.
