Novel mechanism of drug resistance to proteasome inhibitors in multiple myeloma

Multiple myeloma(MM) is a cancer caused by uncontrolled proliferation of antibody-secreting plasma cells in bone marrow, which represents the second most common hematological malignancy. MM is a highly heterogeneous disease and can be classified into a spectrum of subgroups based on their molecular and cytogenetic abnormalities. In the past decade, novel therapies, especially, the first-in-class proteasome inhibitor bortezomib, have been revolutionary for the treatment of MM patients. Despite these remarkable achievements, myeloma remains incurable with a high frequency of patients suffering from a relapse, due to drug resistance. Mutation in the proteasome β5-subunit(PSMB5) was found in a bortezomib-resistant cell line generated via long-term coculture with increasing concentrations of bortezomib in 2008, but their actual implication in drug resistance in the clinic has not been reported until recently. A recent study discovered four resistance-inducing PSMB5 mutations from a relapsed MM patient receiving prolonged bortezomib treatment. Analysis of the dynamic clonal evolution revealed that two subclones existed at the onset of disease, while the other two subclones were induced. Protein structural modeling and functional assays demonstrated that all four mutations impaired the binding of bortezomib to the 20 S proteasome, conferring different degrees of resistance. The authors further demonstrated two potential approaches to overcome drug resistance by using combination therapy for targeting proteolysis machinery independent of the 20 S proteasome.

Proteasome inhibitor treatment in alcoholic liver disease

Oxidative stress, generated by chronic ethanol consumption, is a major cause of hepatotoxicity and liver injury. Increased production of oxygen-derived free radicals due to ethanol metabolism by CYP2E1 is principally located in the cytoplasm and in the mitochondria, which does not only injure liver cells, but also other vital organs, such as the heart and the brain. Therefore, there is a need for better treatment to enhance the antioxidant response elements. To date, there is no established treatment to attenuate high levels of oxidative stress in the liver of alcoholic patients. To block this oxidative stress, proteasome inhibitor treatment has been found to significantly enhance the antioxidant response elements of hepatocytes exposed to ethanol. Recent studies have shown in an experimental model of alcoholic liver disease that proteasome inhibitor treatment at low dose has cytoprotective effects against ethanol-induced oxidative stress and liver steatosis. The beneficial effects of proteasome inhibitor treatment against oxidative stress occurred because antioxidant response elements （glutathione peroxidase 2, superoxide dismutase 2, glutathione synthetase, glutathione reductase, and GCLC） were upregulated when rats fed alcohol were treated with a low dose of PS-34Z （Bortezomib, Velcade）. This is an important finding because proteasome inhibitor treatment up-regulated reactive oxygen species removal and glutathione recycling enzymes, while ethanol feeding alone down-regulated these antioxidant elements. For the first time, it was shown that proteasome inhibition by a highly specific and reversible inhibitor is different from the chronic ethanol feeding-induced proteasome inhibition. As previously shown by our group, chronic ethanol feeding causes a complex dysfunction in the ubiquitin proteasome pathway, which affects the proteasome system, as well as the ubiquitination system. The beneficial effects of proteasome inhibitor treatment in alcoholic liver disease are related to proteasome inhibitor reversibility and the rebound of proteasome activity 72 h post PS-341 administration.

Anti-tumor Action and Clinical Application of Proteasome Inhibitor

Ubiquitin-proteasome pathway mediates the degradation of cell protein, and cell cycle, gene translation and expression, antigen presentation and inflammatory development. Proteasome inhibitor can inhibit growth and proliferation of tumor cell, induce apoptosis and reverse multipledrug resistance of tumor cell, increase the sensitivity of other chemotherapeutic drugs and radiotherapy, and is a novel class of potent anti-tumor agents.

Is 26S proteasome non-ATPase regulatory subunit 6 a potential molecular target for intrahepatic cholangiocarcinoma?

In this editorial we comment on the article by Tang et al published in the recent issue of World Journal of Hepatology.Drug therapy of intrahepatic cholangiocarcinoma(iCCA)poses an enormous challenge since only a small proportion of patients demonstrate beneficial responses to therapeutic agents.Thus,there has been a sustained search for novel molecular targets for iCCA.The study by Tang et al evaluated the role of 26S proteasome non-ATPase regulatory subunit 6(PSMD6),a 19S regulatory subunit of the proteasome,in human iCCA cells and specimens.The authors employed clustered regularly interspaced short palindromic repeat(CRISPR)knockout screening technology integrated with the computational CERES algorithm,and analyzed the human protein atlas(THPA)database and tissue microarrays.The results show that PSMD6 is a gene essential for the proliferation of 17 iCCA cell lines,and PSMD6 protein was overexpressed in iCCA tissues without a significant correlation with the clinicopathological parameters.The authors conclude that PSMD6 may play a promoting role in iCCA.The major limitations and defects of this study are the lack of detailed information of CRISPR knockout screening,in vivo experiments,and a discussion of plausible mechanistic cues,which,therefore,dampen the significance of the results.Further studies are required to verify PSMD6 as a molecular target for developing novel therapeutics for iCCA.In addition,the editorial article summarizes the latest advances in molecular targeted drugs and recently emerging immunotherapy in the clinical management of iCCA,development of proteasome inhibitors for cancer therapy,and advantages of CRISPR screening technology,computational methods,and THPA database as experimental tools for fighting cancer.We hope that these comments may provide some clues for those engaged in the field of basic and clinical research into iCCA.

The Apoptosis of Bovine Lens Epithelial Cells Induced by Proteasome Inhibitor MG132

To investigate the effect of proteasome inhibitor MG132 on the apoptosis of bovine lens epithelial cells （BLECs）, the cells were treated with MG132 at different concentrations for12, 24 and 36 h. The cell viability was analyzed by MTT assay and the effect of MG132 on the apoptosis of BLECs was assessed by flow cytometry （FCM）. The results showed that after treatment for the same period, the inhibitory effect of MG132 on BLECs proliferation was enhanced with the increment of the concentration of MG132 （0, 2, 5, 10, μmol/L） （P〈0.05）. The 50% inhibiting concentration （IC50） was 2.03 μmol/L when the BLECs were treated with MG132 for 36 h. MG132 also induced the apop- tosis of BLECs obviously. FCM showed that the apoptosis index of the cells treated by MG132 at 2 μmol/L for 12 h was （20.24±1.51）%, and that of the control was （0.98±0.20）% respectively （P〈0.01, n=3）. It was concluded that MG132 could lead to apoptosis of BLECs. The decrease of proteasome activity may play an important role in the formation and development of cataract.

Experimental Study on the Mechanism of Reversal of Leukemia Multidrug Resistance by Proteasome Inhibitor Bortezomib

OBJECTIVE In this study, we applied multidrug resistant leukemia cell line expressing mdr1-mRNA to observe changes in mdr1-mRNA, the P-gp, cell cycle and apoptosis before and after bortezomib was used, in order to explore the mechanism of reversal of leukemia multidrug resistance by the proteasome inhibitor bortezomib.METHODS Flow cytometry （FCM） was used to detect the intracellular drug concentration, expression of P-gp, cell apoptosis and cell cycle status of K562/DNR cells before and a er treatment with different concentrations of bortezomib. Fluorescence quantitative PCR was applied to detect the mdr1-mRNA expression in K562/DNR and K562/S cells.RESULTS Bortezomib could increase the intracellular DNR content in K562/DNR cells, but showed no e. ect in K562/S cells.5-100 nmol/L bortezomib could significantly reduce the P-gp/mdr1-mRNA expression in K562/DNR cells in vitro, and showed a dose-dependent effect. There was a statistically significant di. erence （P 〈 0.05） between di. erent concentration groups and the control group. P-gp/mdr1-mRNA expression was negatively correlated with cell apoptosis （r = -0.912 and P 〈 0.01）. After treatment with different concentrations of bortezomib for 24 h,K562/DNR cells in G2 ＋ M phases were significantly increased,while cells in G0 ＋ G1 phases and S phase were significantly decreased, accompanied by an increased apoptotic rate.CONCLUSION Bortezomib can induce G0 ＋ G1 phase to G2 ＋ M phase, and thereby enhance the chemosensitivity of leukemia, and may also reverse the multidrug resistance in leukemia mediated by P-gp overexpression encoded by mdr1 gene. This confi rms that bortezomib can reverse leukemia multidrug resistance at the levels of nucleic acid and protein molecules.

26S proteasome inhibitors inhibit dexamethasone-dependent increase of tyrosine aminotransferase and tryptophan 2,3-dioxygenase mRNA levels in primary cultured rat hepatocytes

Dexamethasone (Dex), a ligand for transcriptional enhancement of tyrosine aminotransferase (TAT) and tryptophan 2,3-dioxygenase (TO) genes, (100 nM) maximally increased these mRNA levels at 12 h and 7 h in primary cultured rat hepatocytes and the nuclear fraction, respectively. Lactacystin (5 μM) and epoxomicin (0.5 μM), 26S proteasome inhibitors, significantly suppressed the Dex-dependent maximum increase of TAT and TO mRNA levels in the cells and the nuclear fraction. Electrophoretic mobility shift assay demonstrated that lactacystin did not affect binding of glucocorticoid receptor to glucocorticoid responsive element. Furthermore, lactacystin did not affect the activation of GRE luciferase reporter by Dex transfected to the cells. The results demonstrate that 26S proteasome is positively involved in the Dex-dependent increase of TAT and TO mRNA levels in the cells and suggest that the mechanism of action of 26S proteasome may be degradation of some RNase(s), which breaks down TAT and TO mRNAs.

Synthetic protease inhibitor-induced inclusions in PC12 cells Potential proteomic characterization of six subunits in the 26S proteasome

Proteasome dysfunction during dopaminergic degeneration induces proteolytic stress, and is a contributing factor for the onset and formation of Lewy bodies. Results from our previous studies showed that synthetic proteasome inhibitor-induced inclusions in PC12 cells contained six subunits in the 26S proteasome. In the present study, mass spectrometry analysis of single protein spots resolved by two-dimensional gel electrophoresis and identified by bioinformatic analysis of peptide mass fingerprint （PMF） data were performed to comprehensively characterize the proteomic profile of the proteasome subunits. Results showed that six subunits in the 26S proteasome were characterized through accurate assignment by PMF data-specific protein identification in protein databases. Additionally, identification of one of the proteasome subunits was further confirmed using a subunit-specific antibody against non-adenosine triphosphatase subunit 11 of the 19S regulatory particle. Results suggest that the potential proteomic profile of six subunits in the 26S proteasome could be established from proteasome inhibitor-induced inclusions in PC12 cells.

PC12细胞的PSI诱导性包含体富集了真核细胞翻译因子(英文)

路易小体(Lewy body, LB) ,位于神经细胞核周(perikaryon)的嗜酸性包含体(eosinophilic inclusion) ,含有广泛的蛋白质组分,其中一部分是组成型蛋白质(consistent organization) ,另外一部分则是选择型蛋白质(selective composition) .为了在体外获得LB中未知蛋白质的新线索,通过人工合成蛋白酶体抑制剂PSI(proteasomal inhibitor ,10μmol/L)作用PC 12细胞48 h,使其产生嗜酸性(staining for eosin)和抗α-synuclein阳性(immunostaining for α-synuclein)的PSI诱导性包含体(PSI-inducedinclusion) ,通过成功的分级分离(fractionation)纯化了完整、纯净的包含体,通过有效的双向电泳(two-dimensional electrophoresis ,2-DE)分离了包含体蛋白质,通过无偏差的基质辅助激光解析-离子化飞行时间质谱(matrix-assisted laser desorption/ionization time-of-flight massspectrometry,MALDITOF MS)鉴定了真核细胞翻译起始因子-3亚单位5(eukaryotic translation initiation factor 3 subunit 5 ,eIF-3ε)、真核细胞延伸因子-2 (eukaryotic elongation factor 2 , eEF-2)和线粒体延伸因子-Tu(mitochondrial elongation factor Tu, EF-Tumt)等真核细胞翻译因子(eukaryotic translation factors) .这一结果提示,当蛋白酶体受到抑制时真核细胞翻译因子被富集到PSI诱导性包含体中,并且可能影响其形成过程.

质谱鉴定PC12细胞蛋白酶体抑制剂PSI-诱导性包含体中的LB蛋白质(英文)

路易(小)体(Lewy body,LB)构成特征的蛋白质组分在体外形成的路易(小)体样包含体(Lewy body-like inclusion)或聚集体(aggresome)中能够获得鉴定.通过蛋白质组学方法鉴定聚集体内蛋白质是一种新的途径.10μmol/L人工合成蛋白酶体抑制剂PSI(proteasomal inhibitor)作用PC12细胞48h,使其产生PSI诱导性包含体(PSI-induced inclusions).通过生物化学分级分离、双向电泳(two-dimensional electrophoresis,2-D)和肽质量指纹鉴定(identification via peptide mass fingerprints,PMF)的蛋白质组学方法,2个涉及突触递质合成的蛋白质、6个26S蛋白酶体亚基、2个细胞骨架蛋白、2个线粒体蛋白、1个抗氧化蛋白和7个分子伴侣蛋白和(或)分子伴侣样蛋白等20个LB蛋白质组分获得鉴定.结果提示,当PC12细胞发生蛋白酶体抑制时,这20个LB蛋白质组分可能被富集到PSI诱导性包含体中.

Histone deacetylase inhibitor MS-275 alone or combined with bortezomib or sorafenib exhibits strong antiproliferative action in human cholangiocarcinoma cells

AIM: To investigate the antiproliferative effect of the histone deacetylase (HDAC) inhibitor MS-275 on cholangiocarcinoma cells alone and in combination with conventional cytostatic drugs (gemcitabine or doxorubicin) or the novel anticancer agents sorafenib or bortezomib. METHODS: Two human bile duct adenocarcinoma cell lines (EGI-1 and TFK-1) were studied. Crystal violet staining was used for detection of cell number changes. Cytotoxicity was determined by measuring the release of the cytoplasmic enzyme lactate dehydrogenase (LDH). Apoptosis was determined by measuring the enzyme activity of caspase-3. Cell cycle status reflected by the DNA content was detected by flow cytometry.RESULTS: MS-275 treatment potently inhibited the proliferation of EGI-1 and TFK-1 cholangiocarcinoma cells by inducing apoptosis and cell cycle arrest. MS-275-induced apoptosis was characterized by activation of caspase-3, up-regulation of Bax and down-regulation of Bcl-2. Cell cycle was predominantly arrested at the G1/S checkpoint, which was associated with induction of the cyclin-dependent kinase inhibitor p21Waf/CIP1. Furthermore, additive anti-neoplastic effects were observed when MS-275 treatment was combined with gemcitabine or doxorubicin, while combination with the multi-kinase inhibitor sorafenib or the proteasome inhibitor bortezomib resulted in overadditive anti-neoplastic effects.CONCLUSION: The growth of human cholangiocarcinoma cells can be potently inhibited by MS-275 alone or in combination with conventional cytostatic drugs or new, targeted anticancer agents.

蛋白酶体抑制剂PSI对大鼠早期糖尿病肾病发病的作用

目的研究泛素蛋白酶体途径(UPP)对大鼠早期糖尿病肾病(DN)发病的可能作用机制及蛋白酶体抑制剂(PSI)对DN的治疗作用。方法用链脲佐菌素(STZ)诱导糖尿病模型后随机分为正常对照组(NC组)、糖尿病对照组(DC组)和PSI治疗组(DP组)。检查体质童、肾重、肾重指数、24 h尿微量白蛋白(24 h U-mAlb)、尿蛋白/尿肌酐比值(Up/Ucr)、肾纤维化情况、纤维连接蛋白(FN)mRNA表达及NF-κB和IκBα蛋白表达。结果在6、8周时,与NC组比较,DC组的体质童明显降低(P<0.05),肾重、肾肥大指数(肾重/体质童)、24 h尿量、Up/Ucr、24 h U-mAlb、空腹血糖、FN mRNA均显著性增加(P<0.05,P<0.01)。与DC组相比,DP组体质童明显增加(P<0.05);肾重、Up/Ucr和24 h U-mAlb、FN mRNA均显著性降低(P<0.05);肾重/体质童、24 h尿量、空腹血糖均有所降低,差异无统计学意义(P>0.05)。Western blot结果显示,与NC组比较,DC组胞浆NF-κB P65蛋白表达显著降低(P<0.05),胞核NF-κB P65蛋白表达增高(P<0.05),而DP组经治疗后与DC组呈现相反改变;与NC组比较,DC组IκBα蛋白表达明显降低(P<0.05),而PSI干预的DP组表达明显高于DC组(P<0.05)。光镜下,6周时,各模型组肾小管轻度扩展,间质无明显增生;8周时,DC组肾小球增大,毛细血管充血,肾小管肿胀,未见明显纤维化改变,DP组以上改变较DC组轻。结论 UPP通过对NF-κB信号通路的泛素化调节从而参与早期DN发生;蛋白酶体抑制剂PSI能改善早期DN,理论上可部分治疗DN。

Cell cycle arrest effect of compound YSY-01A, a new proteasome inhibitor, on HT-29 cells in vitro

Compound YSY-01A, a recently synthesized proteasome inhibitor, has shown potent growth-inhibitory effect on tumor cells in previous researches. However, the mechanism of its inhibitory effects, especially on cell cycle, remains largely unclear. This study aims to evaluate the correlation between cell cycle arrest effect of YSY-01A and its anti-cancer effect, and to probe the possible molecular mechanisms for its effects on human colorectal adenocarcinoma cells HT-29. The results suggested that YSY-01A significantly （P0.05） inhibited cellular proliferation of HT-29 cells in a time and concentration-dependent manner. Furthermore, YSY-01A suppressed the G 2 /M transition of HT-29 cells, whereas the mitotic inhibitor paclitaxel induced M phase accumulation. Further investigation revealed that YSY-01A significantly （P0.05） up-regulated the expression levels of a series of cell cycle related protein, such as cyclin B1, Wee1, p-cdc2 （Tyr15）, p53, p21, and p27. The HT-29 cells only exhibited typical cytotoxic symptom when YSY-01A concentration reached 0.5 μM （P0.05）, which was above the dose we used in the mechanism research. In conclusion, YSY-01A showed remarkable anti-cancer activity on HT-29 cells, and its molecular mechanisms are related to G 2 /M cell cycle transition arrest.

Cell cycle arrest effect of compound YSY-01A, a new proteasome inhibitor,on SK-OV-3 cells

Compound YSY-01A, a recently synthesized proteasome inhibitor, has shown potent growth-inhibitory effect on tumor cells in previous researches. However, the mechanism of its inhibitory effects, especially on cell cycle, remains largely unclear. This study aimed to evaluate the correlation between cell cycle arrest effect of YSY-01A and its anti-cancer effect, and to probe the possible molecular mechanisms for its effects on human ovarian cancer SK-OV-3 cells. The results suggested that YSY-01A significantly （P〈0.05） inhibited cellular proliferation of SK-OV-3 cells in a concentration-dependent and time-dependent manner. Furthermore, YSY-01A induced a G2/M cell cycle arrest of SK-OV-3 cells. Further investigation revealed that YSY-01A significantly （P〈0.05） changed the expression levels of a series of cell cycle related protein, such as cyclin B1, cdc2, and p-cdc2 （T14）. Meanwhile, YSY-01A could inhibit the TNF-a-induced NF-kB nuclear translocation and lead to the increase of 1kBa as well as the decrease of IKK and Gadd45a In conclusion, YSY-01A showed remarkable anti-cancer activity on SK-OV-3 cells, and its molecular mechanisms were related to G2/M cell cycle arrest.

Effects of compound YSY-01A, a novel proteasome inhibitor, on MGC-803 cells and its related mechanism

As a novel proteasome inhibitor, remarkable proliferation inhibitory effect of compound YSY-01A was shown on tumor cells in previous studies. However, few studies has reported its effect on gastric cancer and related mechanism. We evaluated the anti-proliferative effect of compound YSY-01A using MGC-803 cells and its anti-tumor effect using xenograft nu-BALB/c mouse model. Cell proliferation inhibition was assessed by SRB assay. Related protein expression levels were determined by Western blot assay. We observed that the compound YSY-01A had a significant proliferation inhibitory effect on MGC-803 cells in vitro. Experiment in vivo showed that the compound YSY-01A had a remarkable growth inhibitory effect on MGC-803 cells xenograft tumor when it was used either alone or in combination with the conventional chemotherapeutic agent 5-fluorouracil （5-FU）. Furthermore, YSY-01A and 5-FU had a synergistic effect on xenograft tumor. Results of molecular experiment showed that the compound YSY-01A had a remarkable inhibitory effect on TNF-c~ and IFN induced NF-KB nuclear translocation. At the same time, the compound YSY-01A could reduce the expression of IKK-~, IL-I~ and iNOS, while it significantly enhanced the expression of COX-2 in MGC-803 ceils. Taken together, compound YSY-01A had an impressive tumor inhibitory effect, and it worked in NF-KB-related pathway, suggesting that the compound YSY-01A was an effective therapeutic drug for patients with gastric cancer. Higher tumor cell growth inhibition after the treatment in a combination with 5-FU indicated that combining YSY-01A with 5-FU might be more effective for displaying tumor cell growth inhibitory effects on gastric cancer cells.

Study on the dipeptide vinyl sulfonamide derivatives as proteasome inhibitor

On the basis of the Michael-addition mechanism of classical proteasome inhibitors, six dipeptide vinyl sulfonamide and dipeptide vinyl sulfonate derivatives were designed and synthesized. Moreover, an efficient method for the synthesis of g-amino vinyl sulfonamides, key intermediates to the target molecules, was developed via the Wittig-Horner reaction of peptide aldehyde with Wittig reagents derived from methanesulfonamides.

Effects and mechanism of proteasome inhibitor YSY01--A alone or in combination with cisplatin against A549 cells in vitro

YSY01-A, as a novel proteasome inhibitor, has shown remarkable proliferation inhibitory effect on certain types of tumor cells. However, few studies have reported its effect on non-small cell lung cancer （NSCLC）, and its underlying mechanism remains unknown. In our present study, we aimed to figure out the inhibitory effects as well as the mechanism of proteasome inhibitor YSY01-A against A549 cells both individually and in combination with cisplatin. A549 cell proliferation inhibition was assessed by SRB assay. Its related protein expression levels were determined by western blot assay. Moreover, the change of intracellular cisplatin accumulation was examined by ICP-MS assay. The results suggested that YSY01-A significantly （P〈0.001） inhibited the proliferation of A549 cells （IC50 was 36.2 nM for 72 h） in a concentration-dependent and time-dependent manner. Compared with the negative control group, YSY01-A （60 nM, 48 h） down-regulated PI3K/Akt pathway in A549 cells by increasing the expression level of PTEN （P〈0.01）, and decreasing the expression level of PI3K （P〈0.001） and p-Akt/Akt （P〈0.001）. When combined with cisplatin, YSY01-A of different concentrations （5, 10, 20 nM） could significantly increase the inhibition effects on A549 cells compared with the cisplatin alone treatment, showing a synergistic effect. At the same time, YSY01-A could remarkably block the cisplatin-induced down-regulation of hCTR1 in a concentration-dependent manner and increase cisplatin uptake from 2.01 to 2.47 fold （P〈0.001）. In conclusion, compound YSY01-A could significantly inhibit proliferation of NSCLC A549 cells, showing a strong synergistic effect when combined with cisplatin. Down-regulation of PI3K/Akt pathway might be the mechanism of inhibitory effect of YSY0 l-A, and the combination with cisplatin might increase the expression of CTR1 and intracellular cisplatin accumulation.

A new proteasome inhibitor YSY-01A induced autophagy in PC-3M cells

YSY-01A has shown proliferation inhibitory activity to certain types of tumor cells by inhibiting proteasome. How- ever, its effect on autophagy, which is related with the ubiquitin proteasome pathway （UPP）, remains unclear. Our study aimed to find out its effect on autophagy and possible molecular mechanisms. The results suggested that YSY-0 l A significantly （P〈0.001） inhibited proliferation of PC-3M cells （IC50 was 287 nM for 48 h） in a concentration-dependent and time-dependent manner. YSY-01A （100 nM, 3 h） also induced autophagy in PC-3M ceils through increasing the expression of P53 （P〈0.001）, Beclin-1 （P〈0.001） and LC3 （P〈0.001）, and decreasing the expression of p-roTOR （P〈0.001） as compared with the negative control group. Autophagy stayed at a final stage in PC-3M cells after treated with YSY-01A （400 nM） for 12 h. Meanwhile inhibition of autophagy with chloroquine increased the sensitivity to YSY-01A in PC-3M cells. In conclusion, YSY-01A showed high proliferation inhibitory activity of PC-3M cells and it could induce autophagy in PC-3M cells. Inhibiting autophagy increased the cytotoxic activity of YSY-01A in PC-3M cells.

蛋白酶体抑制剂MG132对慢性缺氧致小鼠记忆损伤的作用及其机制

目的探讨蛋白酶体抑制剂MG132对慢性缺氧所致小鼠记忆功能损伤的作用及其机制。方法(1)利用低氧工作站构建小鼠中脑多巴胺能神经元MN9D细胞缺氧损伤模型。将MN9D细胞分为常氧组及缺氧12 h、24 h和48 h组,观察缺氧对MN9D细胞中酪氨酸羟化酶(TH)、泛素的K48链(Ub-K48)和Ub-K63表达的影响;将MN9D细胞分为常氧组、缺氧组、缺氧+MG132(25、50、100、200)μmol/L组,观察MG132对缺氧细胞中上述蛋白表达的影响。(2)利用低压舱建立低压缺氧小鼠记忆功能损伤模型。将C57小鼠随机分为常氧组、缺氧3 d组、缺氧21 d组,每组10只,观察低压低氧对小鼠中脑黑质致密部(SNc)TH、Ub-K48和Ub-K63表达的影响;将小鼠随机分为常氧组、缺氧21 d组、缺氧21 d+MG132组,每组8只,观察MG132对缺氧所致小鼠空间记忆损伤的影响。(3)采用Western blotting检测不同缺氧时长及MG132预处理再低氧处理的MN9D细胞中TH、Ub-K48和Ub-K63的蛋白表达水平;采用新物体识别测试检测各组小鼠记忆功能,免疫荧光染色检测SNc区TH阳性免疫反应面积百分比,Western blotting检测小鼠SNc区TH、Ub-K48和Ub-K63表达水平。结果(1)与常氧组比较,缺氧24 h组MN9D细胞中Ub-K48和Ub-K63表达水平增高(P<0.05),TH表达水平降低(P<0.05);各缺氧组Ub-K48/TH和Ub-K63/TH表达水平均增高(P<0.05)。与缺氧组比较,缺氧+MG132100μmol/L组和缺氧+MG132200μmol/L组MN9D细胞中Ub-K48/TH和Ub-K63/TH表达水平降低(P<0.05)。(2)与常氧组比较,缺氧3 d组和缺氧21 d组小鼠中脑SNc区TH表达水平降低(P<0.001),Ub-K48/TH和Ub-K63/TH表达水平升高(P<0.05);缺氧21 d组小鼠新物体识别指数降低(P<0.01),SNc区多巴胺能神经元TH阳性免疫反应面积百分比降低(P<0.05)。与缺氧21 d组比较,缺氧21 d+MG132组小鼠新物体识别指数升高(P<0.01)。结论蛋白酶体抑制剂MG132可改善慢性缺氧所致小鼠记忆损伤,其机制可能与抑制Ub-K48和Ub-K63,上调多巴胺能神经元TH表达有关。

蛋白酶体抑制剂致血栓性微血管病的文献分析

目的:探讨蛋白酶体抑制剂(PI)相关血栓性微血管病(TMA)的发生规律和临床特点,为临床安全用药提供参考。方法:检索中国知网、万方数据库、维普数据库、PubMed、Web of Science等数据库中收录的PI相关TMA的案例报道,检索时间为建库至2023年4月30日。对患者基本信息、用药情况、TMA的临床表现、实验室检查、治疗及预后进行汇总分析。结果:纳入文献37篇,涉及患者92例,其中男性46例(占50.00%),女性29例(占31.52%),性别不详17例(占18.48%);平均年龄为(61±13)岁。TMA的中位发病时间为64 d,临床表现以发热、乏力、恶心/呕吐、少尿/无尿为主。因1例患者出现2次TMA,则合计93例次TMA,患者血小板计数明显降低,中位值为19.5×10^(9)/L,其中0~50×10^(9)/L的患者最多(52例次,占55.91%);64例次患者(占68.82%)的血清肌酐水平升高,其中>177~445μmol/L的患者最多(32例次,占34.41%)。停药和支持治疗后(共93例次),76例次患者(占81.72%)痊愈/好转,6例次(占6.45%)有后遗症,5例次(占5.38%)死亡。PI相关TMA中,主要涉及的药物为卡非佐米(67例次,占72.04%)。结论:应重视PI所致TMA,应用PI时应考虑患者性别、药物种类等因素;根据临床表现及实验室检查结果,尽早识别不良反应,保障患者用药安全。