Icariin plus curcumol enhances autophagy through the mTOR pathway and promotes cathepsin B-mediated pyroptosis of prostate cancer cells

Objective:To examine the effect of icariin plus curcumol on prostate cancer cells PC3 and elucidate the underlying mechanisms.Methods:We employed the Cell Counting Kit 8 assay and colony formation assay to assess cell viability and proliferation.Autophagy expression was analyzed using monodansylcadaverine staining.Immunofluorescence and Western blot analyses were used to evaluate protein expressions related to autophagy,pyroptosis,and the mTOR pathway.Cellular damage was examined using the lactate dehydrogenase assay.Moreover,cathepsin B and NLRP3 were detected by co-immunoprecipitation.Results:Icariin plus curcumol led to a decrease in PC3 cell proliferation and an enhancement of autophagy.The levels of LC3-Ⅱ/LC3-Ⅰand beclin-1 were increased,while the levels of p62 and mTOR were decreased after treatment with icariin plus curcumol.These changes were reversed upon overexpression of mTOR.Furthermore,3-methyladenine resulted in a decrease in inflammatory cytokines,pyroptosis-related protein levels,and lactate dehydrogenase concentration,compared to the icariin plus curcumol group.Inhibiting cathepsin B reversed the regulatory effects of icariin plus curcumol.Conclusions:Icariin plus curcumol demonstrates great potential as a therapeutic agent for castration-resistant prostate cancer by enhancing autophagy via the mTOR pathway and promoting pyroptosis mediated by cathepsin B.These findings provide valuable insights into the molecular mechanisms underlying the therapeutic potential of icariin and curcumol for prostate cancer treatment.

Microglial cathepsin B as a key driver of inflammatory brain diseases and brain aging

Interleukin-1βis a potent proinflammatory cytokine that plays a key role in the pathogenesis of the brain aging and diverse range of neurological diseases including Alzheimer’s disease,Parkinson’s disease,stroke and persistent pain.Activated microglia are the main cellular source of interleukin-1βin the brain.Cathepsin B is associated with the production and secretion of interleukin-1βthrough pyrin domain-containing protein 3 inflammasome-independent processing of procaspase-3 in the phagolysosomes.The leakage of cathepsin B from the endosomal-lysosomal system during aging is associated with the proteolytic degradation of mitochondrial transcription factor A,which can stabilize mitochondrial DNA.Therefore,microglial cathepsin B could function as a major driver for inflammatory brain diseases and brain aging.Orally active and blood-brain barrier-permeable specific inhibitors for cathepsin B can be potentially effective new pharmaceutical interventions against inflammatory brain diseases and brain aging.

Study on the role of Cathepsin B and JNK signaling pathway in the development of cerebral aneurysm

Objective: To investigate the correlation between JNK signal and the apoptosis of VSMC as well as the expression of Cathepsin B and to explore the role of JNK signal in the development of cerebral aneurysm. Methods: Rat models of cerebral aneurysm were established and histopathologic changes of cerebral aneurysm and the apoptosis of VSMC were analyzed. Rat models were respectively subject to subcutaneous injection of Cathepsin B si RNA and JNK inhibitor SP600125. Western blot technique was used to detect the expression of proteins like Cathepsin B, Caspase-3, and p-JNK. Spearman's rho was used to examine the correlation between p-JNK and Cathepsin B, as well as the expression of relevant proteins. Results:The success rate of modeling rats with cerebral aneurysm was 88.75%. After the respective injection of Cathepsin B si RNA, SP600125 and their combination, the cell densities of VSMC of rats with cerebral aneurysm all increased significantly(P<0.05 or P<0.01), but the apoptosis rate of VSMC decreased significantly(P<0.01). Compared with normal rats, the expression of Cathepsin B, Caspase-3 and p-JNK in cerebral aneurysm models increased significantly. Effectively intervening Cathepsin B genes with Cathepsin B si RNA could significantly inhibit the expression of Cathepsin B and Caspase-3, but hardly influence the expression of p-JNK. JNK inhibitor SP600125 had no influence on the expression of Cathepsin B and Caspase-3, but effectively inhibited the expression of p-JNK. In cerebral aneurysm tissues, positive correlation was observed between the expression of p-JNK and Cathepsin B, the correlation coefficient was r=0.640. Conclusion: After the attack of cerebral aneurysm, proteins like Cathepsin B, Caspase-3 and p-JNK are all involved in the apoptosis of VSMCs. This process may be realized by Cathepsin B which activates the apoptosis mechanism of Caspase-3 and mediate the apoptosis of VSMC through the JNK signaling pathway. Therefore, silencing Cathepsin B gene or inhibiting the conduction through JNK signaling pathway can mitigate the apoptosis of vascular smooth muscle cells in cerebral aneurysm.

Catechu Inhibiting Cathepsin B Activity and Motility of HT1080 Cells

We reported that Catechu extract has a significant inhibitory effect on cathepsin B activity. The IC50 value for the Catechu extract against cathepsin B was 7.6 μg/mL. In addition, we showed that HT1080 human fibrosarcoma cells express cathepsin B and Catechu modulate the invasion and motility of these cells. These data may provide molecular mechanisms for the therapeutic effects of Catechu.

小麦颖果与根部Cathepsin B-like蛋白的初步研究

利用免疫组织化学技术观察了小麦(Triticum aestivum L.)灌浆时期颖果内以及苗期根部原生韧皮部Cathepsin B-like蛋白的分布以及活性变化。结果表明,在开花后1~9 d的小麦颖果内,Cathepsin Blike蛋白主要分布在内果皮细胞以及灌浆池两侧的维管束中;在开花后12~24 d的颖果中,糊粉层内的Cathepsin B-like蛋白含量逐渐增加,两侧维管束细胞中的Cathepsin B-like蛋白消失,颖果背部内果皮细胞的Cathepsin B-like蛋白含量减少并在细胞边缘出现聚集现象;在小麦苗期根部的原生韧皮部中,随着韧皮部筛分子的成熟,筛分子内的Cathepsin B-like蛋白含量逐渐下降直至消失。

Putative roles of cathepsin B in Alzheimer's disease pathology: the good, the bad, and the ugly in one?

Alzheimer＇s disease（AD）is a fatal progressive neurodegenerative disorder characterized by loss in memory,cognition,and executive function and activities of daily living.AD pathogenesis has been shown to involve loss of neurons and synapses,cholinergic deficits,amyloid-beta protein（Aβ）deposition,tau protein hyperphosphorylation, and neuroinflammation.

Efficient Utilization of 6-Aminouracil to Synthesize Fused and Related Heterocyclic Compounds and Their Evaluation as Prostate Cytotoxic Agents with Cathepsin B Inhibition

6-aminouracil 1 was utilized to introduce different heterocyclic rings at C-6 position through various synthetic strategies. The synthesized compounds bear rings that are either directly attached to the uracil back bone as in compounds 6, 12a-c and 15, or attached through an amino bridge as compounds 3a-c, 5a, b, 7a, b, 9 and 10, or through an imino bridge as compound 18. Also, compounds 4, 8, 11a-c, 14, 16 and 17 bearing biologically active side chains were synthesized. In addition to, compounds 13, 19, 20, 21 and 22 bear fused rings to the uracil backbone. All synthesized compounds were evaluated for their anticancer activity against prostate PC3 cell line using in-vitro sulforhodamine-B (SRB) method, from which compounds 3a, c, 4, 5a, b, 6, 7a, b, 11a-c, 12a, b, 17 and 20 were the most active. These active compounds were further evaluated for their ability to inhibit cathepsin B enzyme by using enzyme-linked immunosorbent assay, which revealed that compounds 5a, b, 7a, 11a, 12a and 17 exhibited more than 50% inhibition of cathepsin B. Among which the phenyl thiourea derivative 17 was the most active exhibiting 82.3% inhibition, while the reference doxorubicin exerted 18.7% inhibition.

喉癌患者外周血Cathepsin B、L及Stefin A水平检测的意义

目的探讨喉癌患者外周血组织蛋白酶B(Cathepsin B)、组织蛋白酶L(Cathepsin L)及内源性抑制剂(Stefin A)表达水平的变化与临床诊断和预后的关系。方法收集我院确诊的喉癌患者及正常对照者血清,酶联免疫吸附测定法(Elisa)检测60例喉癌患者及30位正常对照者血清中Cathepsin B、L及Stefin A水平。结果喉癌患者血清中CathepsinB、L水平显著高于正常对照者(P<0.01),二者表达水平呈显著正相关(r=0.434 1,P<0.05);Stefin A水平显著低于正常对照者(P<0.01),但与Cathepsin B、L无显著相关性。结论喉癌患者血清中存在高水平的Cathepsin B、L及低水平的Stefin A,提示检测血清中Cathepsin B、L及Stefin A含量可协助诊断及判断预后。

CATHEPSIN B EXPRESSION AND ITS RELATIONSHIP WITH MICROVESSEL DENSITY AND BIOLOGICAL BEHAVIOUR OF COLORECTAL CARCINOMA

Objective: To investigate cathepsin B(CB) expression in colorectal carcinoma and its relationship with microvessel density (MVD) and biological behavior. Methods: CB and MVD were detected by immunohistochemistry in 47 cases of colorectal carcinoma. Results: The expression of CB in mucinous colorectal carcinoma was significantly higher than that in no-mucinous colorectal carcinoma. There was significant difference (P<0.05). The MVD in group with positive CB was stronger than that in group with negative CB. There was also significant difference (P<0.05). Conclusion: The results suggest that CB expression has correlation with MVD, invasion and metastasis in colorectal carcinoma, especially in mucinous colorectal carcinoma.

Hepatoprotective effects of cathepsin B inhibitor on acute hepatic failure induced by lipopolysaccharide/D-galactosamine in mice

BACKGROUND:Increasing evidence suggests that the inactivation of cathepsin B attenuates hepatocyte apoptosis and liver damage.This study aimed to investigate the protective effects of a cathepsin B inhibitor(CA-074me) on lipopolysaccharide(LPS)/D-galactosamine(D-GalN)-induced acute hepatic failure(AHF) in mice.METHODS:Mice were intraperitoneally injected with a combination of LPS/D-GalN to induce AHF with or without CA-074me pretreatment.The cumulative survival rates were calculated 48 hours after the induction of AHF.As well as changes in biochemical indicators and liver histology,hepatocyte apoptosis was assessed using a TUNEL method.Serum tumor necrosis factor-α(TNF-α) production,caspase-3,caspase-8,and caspase-9 activity was evaluated.Cytosolic cytochrome c and Bcl-2 expression were measured by Western blotting.RESULTS:The marked elevation in serum aminotransferase activity and prothrombin time found in LPS/D-GalN-treated mice was significantly improved by pretreatment with CA074me.The efficacy of CA-074me was also confirmed by histological analysis and TUNEL assay.The survival rate significantly improved in LPS/D-GalN-induced mice given CA-074me compared with untreated mice.LPS/D-GalNinduced caspase-3 and caspase-9 activation was remarkably suppressed by CA-074me.However,the increased levels of serum TNF-α and elevated caspase-8 activity in AHF mice were not significantly reduced by CA-074me.Moreover,CA074me sharply reduced the increased expression of cytosolic cytochrome c and markedly augmented Bcl-2 expression.CONCLUSION:These results suggest that CA-074me has a protective effect in acute hepatic failure induced by LPS/D-GalN.

Role of cathepsin B-mediated apoptosis in fulminant hepatic failure in mice

AIM: To investigate the pathogenic role of cathepsin B and the protective effect of a cathepsin B inhibitor (CA074Me) in fulminant hepatic failure in mice. METHODS: LPS/D-Gal N was injected into mice of the model group to induce fulminant hepatic failure; the protected group was administered CA-074me for 30 min before LPS/D-Gal N treatment; the normal group was given isochoric physiologic saline. Liver tissue histopathology was determined with HE at 2, 4, 6 and 8 h after Lps/D-Gal injection. Hepatocyte apoptosis was examined by TUNEL method. The expression of cathepsin B in liver tissues was investigated by immunohistochemistry, Western blot and RT-PCR. RESULTS: Compared with the normal group, massive typical hepatocyte apoptosis occurred in the model group; the number of apoptotic cells reached a maximum 6 h after injection. The apoptosis index (AI) in the protected group was clearly reduced (30.4 ± 2.8 vs 18.1 ± 2.0, P < 0.01 ). Cathepsin B activity was markedly increased in drug-treated mice compared with the normal group (P < 0.01). Incubation with LPS/D-Gal N at selected time points resulted in a timedependent increase in cathepsin B activity, and reached a maximum by 8 h. The expression of cathepsin B was significantly decreased in the protected group (P < 0.01). CONCLUSION: Cathepsin B plays an essential role in the pathogenesis of fulminant hepatic failure, and the cathepsin B inhibitor CA-074me can attenuate apoptosis and liver injury.

Crocus sativus L.produces anti-inflammatory effects and regulates the NLRP3–NF-κB pathway

Objective:This study aimed to evaluate the anti-inflammatory effects of petal and stamen extracts of saffron crocus(Crocus sativus)and explore the underlying mechanism.Methods:Local and systemic inflammation models were used to investigate the anti-inflammatory effects of C.sativus.A xyleneinduced inflammation model or lipopolysaccharide(LPS)-induced inflammation model was used in this study.C.sativus petal and stamen extracts were each administered to the mice in the xylene and LPS models by gavage for 14 d at 0.1 and 0.4 g/kg doses,respectively.Enzyme-linked immunosorbent assay(ELISA)was used to measure the concentrations of tumor necrosis factor(TNF)-αand interleukin(IL)-1βin mouse serum.Hematoxylin and eosin(H&E)staining was used to observe the pathological changes in the ear in the xylene-induced inflammation model and in the spleen in the LPS-induced inflammation model.NOD-like receptor thermal protein domain associated protein 3(NLRP3)protein levels within the nuclear factor-kappa B(NF-κB)pathway were assessed using western blotting.RAW264.7 cells were treated with LPS(5μg/mL)and LPS+C.sativus(0.05,0.1,and 0.2 mg/mL)for 24 h,and a Cell Counting Kit-8 was used to measure cell proliferation.Changes in NLRP3 and NF-κB levels were evaluated by western blotting.Results:Petal and stamen extracts of C.sativus attenuated the anti-inflammatory effects in local or systemic inflammatory models and repaired pathological changes in the ear in the xylene-induced inflammation model and spleen in the LPS-induced inflammation model.These extracts also decreased the concentrations of TNF-αand IL-1βin the mouse serum in the LPS-induced inflammation model.C.sativus downregulated NLRP3 protein level through the NF-κB pathway and downregulated LC-3 and BECLIN1 in vivo and in vitro.Carbonyl Cyanide3-ChloroPhenylhydrazone(CCCP)weakened the effects of C.sativus on the NLRP3–NF-κB pathway.Conclusion:C.sativus has anti-inflammatory effects and regulates the NLRP3-NF-κB pathway.

Relation of Cystatin C and Cathepsin B Expression to the Pathological Grade and Invasion of Human Gliomas

OBJECTIVE To explore the relation of cystatin C and cathepsin B expression to the pathological grade and invasion of human gliomas. METHODS A immunohistochemical method was used to detect the expression of cystatin C and cathepsin B in 57 glioma samples. RESULTS The expression of cystatin C in high-grade （Grade Ⅲ-Ⅳ ）gliomas was significantly weaker than that in low-grade（Grade Ⅰ-Ⅱ, P=0.0001）. On the other hand, the expression of cathepsin B in high-grade gliomas was significantly stronger than that in low-grade （P=0.0001）. Cystatin C expression correlated inversely with cathepsin B expression in gliomas （P=0.01）. CONCLUSION Cystatin C and cathepsin B expression is related to the pathological grade and invasion of gliomas. Combining detection of cystatin C and cathepsin B expressions might provide significant information for clinical assessment of maglignant phenotypes and invasion of gliomas.

S53G SNP in Cathepsin B: Can Be Used as a Molecular Biomarker to Breast Cancer?

Cathepsin B (CTS B) is a proteolytic enzyme that participates in several important biological processes. However, when it is altered can be involved in development of breast cancer, a disease with high incidence and mortality rate among women. Many studies have shown a correlation between high CTS B expression and breast tumor. Furthermore, it has been shown that the SNP rs1803250 (S53G) leads to structural and functional changes in protein that can make it pathogenic. The present study aimed to evaluate a possible association of SNP rs1803250 (S53G) with breast cancer. For this, real-time PCR was performed on a sample collected in the State of Pará, with 127 patients and 122 controls. The SNP frequency in this region was 0.12, according to a research project in progress that aims to identify Amerindians molecular alterations. This indicates that the SNP is found in region with a distribution close to worldwide frequency of 0.09. Our results showed that the SNP was in Hardy-Weinberg Equilibrium in collected sample, but C variant allelic frequency was 0.08 in both patients and control groups, which is extremely similar to global average. Moreover, homozygotes CC was not found in the sample and SNP genotypes frequency in patients and control groups was not significantly different. In addition, statistical analysis showed that the SNP did not have to correlate with tumor subtypes nor with tumor staging. Therefore, according to the analyzed sample, the SNP rs1803250 has no association with breast cancer and it cannot be considered a molecular biomarker for breast cancer.

脑缺血再灌注损伤与自噬相关蛋白Beclin-1和Cathepsin B表达相关

目的:探讨自噬的激活在缺血再灌注损伤中的作用。方法:将45只Wistar大鼠随机分为假手术组(Sham组)、缺血再灌注组(I/R组)、雷帕霉素组(RAPA组),每组15只。制作大脑中动脉缺血再灌注、缺血再灌注+雷帕霉素干预大鼠模型,脑缺血2 h后再灌注,24 h后进行神经功能缺损评分、HE染色观察细胞病理学改变、Western Blot法检测自噬相关蛋白Beclin-1和Cathepsin B的表达。结果:RAPA组的Beclin-1及Cathepsin B表达高于I/R组,神经功能缺损程度低于I/R组,差异有统计学意义(P<0.01),细胞坏死程度减轻。结论:雷帕霉素激活自噬对缺血再灌注大鼠有明显的神经保护作用,这种保护作用与Beclin-1和Cathepsin B表达有关。

Rhizobium Inoculation and Micronutrient Addition Influence the Growth,Yield,Quality and Nutrient Uptake of Garden Peas(Pisum sativum L.)

Garden pea productivity and qualities are hampered in zinc(Zn),boron(B),and molybdenum(Mo)deficient soil.Thus,the combination of micronutrients(i.e.,Zn,B,and Mo)and rhizobium is necessary to increase the productivity and quality of garden peas,since this management for garden peas is neglected in Bangladesh.Therefore,the present study was made to assess the effectiveness of rhizobium inoculant singly or in combination with the micronutrients(i.e.,Zn,B,and Mo)on growth,yield,nutrient uptake,and quality of garden peas.Treatments were:T_(1)=Control,T_(2)=Rhizobium inoculation at 50 g/kg seed,T_(3)=T_(2)+Zn_(3)Mo1,T_(4)=T_(2)+B_(2)Mo1,T_(5)=T_(2)+Zn_(3)B_(2),T_(6)=T_(2)+Zn_(3)B_(2)Mo1 and T_(7)=Zn_(3)B_(2)Mo1.All treatments were arranged in a randomized complete block design and repeated all treatments in three times.The application of 3 kg Zn,2 kg B,and 1 kg Mo ha^(−1)with inoculation of Rhizobium at 50 g kg^(−1)seed(T_(6))facilitated to increase of 44.8%in the green pod and 29.7%seed yield over control.The same treatment contributed to attaining the maximum nodulation(25.3 plant^(−1)),Vitamin C(43.5 mg 100 g^(−1)),protein content(22.2%),and nutrient uptake as well as accumulation in garden peas.Among all treatment combinations,treatment T_(6)was found superior to others based on microbial activities,soil fertility,and profitability.The results of the study found that the application of 3 kg Zn,2 kg B,and 1 kg Mo ha^(−1)in combination with Rhizobium inoculation(50 g kg^(−1)seed)can improve the yield and quality of garden peas.The results of the study have the potential for the areas,where there is no use of Rhizobium inoculant or Zn,B,and Mo fertilizer for cultivation of garden pea.

Bioactive chemical constituents from the marine-derived fungus Cladosporium sp.DLT-5

A new isochromanone,cladosporinisochromanone(1),accompanied by 15 known compounds(2–16)were obtained from secondary metabolites produced by marine-derived fungus Cladosporium sp.DLT-5.NMR and HRESIMS spectra elucidation determined the planar structure of 1.Subsequent electronic circular dichroism(ECD)experiment assigned the absolute configuration of 1.Compounds 1,2,4–6,and 10 displayed different degrees of neuroprotective activities on human neuroblastoma cells SH-SY5Y.Five compounds(1,3–5,and 13)emerged resistance to protein tyrosine phosphatase 1B(PTP1B),further kinetic analysis and molecular docking study indicated that the most potent compound 13(IC50value of 10.74±0.61μmol/L)was found as a noncompetitive inhibitor for PTP1B.Surface plasmon resonance(SPR)and molecular docking studies also demonstrated the interaction between compound 12 and Niemann-Pick C1 Like 1(NPC1L1),which has been identified as significant therapeutic target for hypercholesteremia.In addition,compounds 3,6,and 14 showed attractive inhibitory activity against the phytopathogenic fungi:Colletotrichum capsici.Therefore,library of Cladosporium metabolites is enriched and new active uses of known compounds are explored.

Cathepsin B-RNAi-lentivirus新生血管形成的研究抑制小鼠视网膜

背景 视网膜新生血管性疾病是一种严重影响视力的眼病.研究表明,cathepsin B参与新生血管的生成,寻找抑制视网膜新生血管形成的药物可为此类疾病的分子机制研究提供依据. 目的 研究cathepsin B-RNAi-lentivirus对小鼠视网膜新生血管的抑制作用. 方法 将7日龄清洁级C57BL/6J小鼠与其母鼠共同置于氧体积分数为（75±2）％的密闭氧箱内5d,制作视网膜新生血管模型,5d后返回正常环境.应用随机数字表法将60只小鼠随机分为模型对照组、阴性对照组和基因治疗组,每组20只.模型对照组小鼠不给予任何药物干预,阴性对照组小鼠玻璃体腔内注射空载体与辅助载体包装成的无目的基因的空病毒颗粒（NC-GFP-LV）1 μl,基因治疗组以同样的方法注射eathepsin B-RNAi-lentivirus 1μl.注射5d后各组分别应用随机数字表法随机处死7只小鼠,获取14只眼的视网膜,采用real-time PCR法检测小鼠视网膜中cathepsin BmRNA的表达量（2△△Ct）,另外同时间点同法分别处死8只小鼠,获取16只眼球的视网膜,采用Western blot法检测各组小鼠视网膜中cathepsin B蛋白的相对表达量（cathepsin B/β-actin）.注射5d后各组分别取剩余5只小鼠行异硫氰酸葡聚醛荧光素（FITC-dextran）心脏灌注,并处死动物,制备10只眼的视网膜铺片,荧光显微镜下观察和比较各组小鼠视网膜新生血管的形态和数量. 结果 基因治疗组小鼠视网膜中cathepsin B mRNA的表达水平（2-△△Ct）为0.740.12,明显低于模型对照组及阴性对照组的1.66±0.17和1.58±0.29,差异均有统计学意义（q=0.746、1.588,P＜0.01）.基因治疗组小鼠视网膜中cathepsin B蛋白的表达水平（cathepsin B/β-actin）为0.64±0.06,明显低于模型对照组及阴性对照组的0.93±0.09和0.96±0.09,差异均有统计学意义（q=0.637、0.894,P＜0.01）.小鼠视网膜荧光染色结果显示,模型对照组和阴性对照组小鼠视网膜新生血管分层及分支多,血管走形扭曲,部分血管可见荧光素渗漏；基因治疗组小鼠血管走形较直,血管分支少,新生血管数量少. 结论 Cathepsin B-RNAi-lentivirus转染能有效抑制小鼠视网膜新生血管的形成.

IGF-1 promotes the growth and metastasis of hepatocellular carcinoma via the inhibition of proteasome-mediated cathepsin B degradation

AIM: To investigate the molecular mechanisms of the high IGF-1 level linking diabetes and cancers, which is a risk factor.METHODS: We used cell growth, wound healing and transwell assay to evaluate the proliferation and metastasis ability of the hepatocellular carcinoma(HCC) cells. Western blot and reverse transcription polymerase chain reaction were used to assess a previously identified lysosomal protease, cathepsin B(CTSB) expression in the HCC cell lines. C57 BL/6J and KK-Ay diabetic mice are used to detect the growth and metastasis of HCC cells that were depleted with or without CTSB sh RNA in vivo. Statistical significance was determined by Student's t-test.RESULTS: IGF-1 promoted the growth and metastasis of the HCC cell lines via its ability to enhance CTSB expression in both a time-dependent and concentration-dependent manner. HCC cells grew much faster in diabetic KK-Ay mice than in C57 BL/6J mice. Additionally, more metastatic nodules were found in the lungs of KK-Ay mice than the lungs of C57 BL/6J mice. CTSB depletion protects against the tumorpromoting actions of IGF-1 in HCC cells, as well tumor growth and metastasis both in vitro and in vivo.IGF-1 did not change the m RNA levels of CTSB but prolonged the half-life of cathepsin B in Hepa 1-6 and H22 cells. Our results showed that IGF-1 promotes the growth and metastasis of the HCC cells most likely by hindering CTSB degradation mediated by the ubiquitinproteasome system(UPS), but not autophagy. Overexpression of proteasome activator 28, a family of activators of the 20 S proteasome, could not only restore IGF-1-inhibited UPS activity but also decrease IGF-1-induced CTSB accumulation.CONCLUSION: Our study demonstrates that IGF-1 promotes the growth and metastasis of hepatocellular carcinoma by inhibition of proteasome-mediated CTSB degradation.