The Expression And Regulation Of Glucocorticoid Receptor Isoforms In Glucocorticoid Resistance Of Patients With Multiple Myeloma

Objective:To study the expression of glucocorticoid receptor(GR) isoforms α、β、γ、P inglucocorticoid resistance of patients with multiple myeloma; to investigate the role ofSerine/arginine-rich protein30（SRp30）、SRp40on the regulation of GR isforms; toexplore the role of heat shock protein90(HSP90)、nuclear factor kappa B(NF-κB) andactivating protein-1(AP-1) in the network of multiple myeloma(MM) patients, as wellas the relationship with GC resistance.Methods:67diagnosed patients with MM(33male;34female; median age57) from theHematology department of the First Affiliated hospital of Dalian Medical Universityfrom1st May2009to31st May2012were enrolled in this study.The diagnosis andtreatment of MM patients was conformed according to the Diagnosis and TreatmentStandards of Hematology (version3.0) which was edited by Zhinan Zhang and Ti Shen.All patients were divided into two groups: the newly diagnosed group (22cases,12male;10female; median age61), relapsed group (45cases,21male;24female; medianage57). All the patients were treated with GC regimen (including VAD, VDT and MPprogram), then they were devidied into sensitive group37cases(19male;18female;median age57.5; CR or VGPR) and resistant group23(9male;14female; median age56; PR,nCR or Progression) according to the efficacy of patients evaluated after fourcycles.25cases with non-neoplastic disease patients were served as the control group(15male;10female; median age58). The test had applied for registration of clinicaltrials. Trial registration: CHiCTR-RCH-12002872. The mRNA expression of GRisoforms α、β、γ、P、SRp30、SRp40、HSP90、NF-κB and AP-1was detected by Realtime RT-PCR(SYBR Green I method). The results of datas were analysed by the SPSS16.0soft ware package.Result:1. The mRNA expression of the four GR isoforms in MM patients and the controlgroups showed the following trend: GRα>GRP>GRγ>GRβ, the frequency of GRα、GRP、GRγ and GRβ expression in the control group was76.71%、18.78%、4.50%、0.01%respectively, while in MM patients, it was46.30%、29.30%、23.64%、0.07%respectively. The frequency of two groups was significant different (P=0.001).Compared to the sensitive group, the mRNA expression of GRα was significantlydecreased in the resistant group (9.32v23.20，P=0.013), the mRNA expression of GRγwas significant higher in the resistant group (7.81v1.74, P=0.029). The expression ofGRγ showed a significant negative correlation with GRα in MM patients (r=-0.41，P=0.007). Compared to the sensitive group, there was increased expression of GRP inthe resistant group, but there was no significant different (10.97v5.45,P=0.053).2. There was no different in the expression of SRp30c and SRp40between the MMpatients and the control group (P>0.05). Compared to the sensitive group, there wasincreased expression of SRp40in the resistant group (90.87v60.79), while there wasno different in SRp30c. Compared to the control group, there were an increasedexpression of SRp40(90.87v51.83，P=0.043). And there were no correlation betweenthe expression of SRp30c、 SRp40and the the expression of GRα、GRβ、GRγ andGRP(P>0.05).3.Compared to the control group, there were a decreased expression of HSP90andHSP90/GRα(28.36v113.44，P=0.020；1.44v23.75，P=0.001). There was no differentbetween newly diagnosed group and the relapsed group in the expression of HSP90(23.54v28.36,P=0.901). Compared to the sensitive group, the mRNA expression ofHSP90had a decreased trend in the resistant group, but but there was no significantdifference(28.26v34.22，P=0.777).4.Compared to the control group, there was a significant increased expression ofNF-κB in MM patients(2073.71v1319.51，P=0.045), while the mRNA expression ofAP-1had a decreased trend(683.20v205.90, P=0.285). Compared to the sensitivegroup, the mRNA expression of NF-κB and AP-1were significant higher in the resistantgroup(3605.00v1394.74，P=0.030；389.58v96.05，P=0.042), while NF-κB/GRαand AP-1/GRαwere more higher (513.36v64.00，P=0.011；69.23v7.11，P=0.001). Conclusion:1. GRα accounted for the highest occurrence of four GR isoforms. GRα was amajor subtype, which mediated the effect of GC. The expression of GRβ was very tiny,which could not mediate the effect of GC. The frequency of four isoforms wassignificant different between MM patients and the control group because of disorder ofinner environment.2. There was a significant decreased expression of GRα, while increasedexpression of GRγ and GRP in MM patients, especially GRγ. The expression of GRγshowed a significant negative correlation with the expression of GRα in MM patients.We evolved that GRγ and GRP could interfere in the expression of GRα in GCresistance.3. Compared to the sensitive group, there was increased expression of SRp40in theresistant group, while there was a significant increased expression of SRp40compare tothe control group. We evolved that the expression of SRp40could partly play a role ofsplicing of GR pre-RNA. There was no different between the expression of SRp30c andGC resistance in MM patients.4. The expression of HSP90was decreased in MM patients, there was a significantdecreased HSP90/GRαcompare to the control group. We evolved that the lack ofHSP90could affect the conformation of GRα, and then affect the function of GRα.5. There was a significant increased expression of NF-κB in MM patients, as wellas the newly diagnosed group and the relapsed group, compared to the control group.We evolved that there was closely relationship between the occurent of MM and NF-κB.Compared to the sensitive group, the expression of NF-κB and AP-1were significantincreased in the resistant group, while NF-kB/GRα and AP-1/GR were more higher inthe resistance group. We evolved that the expression of NF-κB and AP-1could interferethe effect of GC through repressing the transcription of GRα.