Design, in silico evaluation, and in vitro verification of new bivalent Smac mimetics with pro-apoptotic activity.

Bivalent Smac mimetics have been shown to possess binding affinity and pro-apoptotic activity similar to or more potent than that of native Smac, a protein dimer able to neutralize the anti-apoptotic activity of an inhibitor of caspase enzymes, XIAP, which endows cancer cells with resistance to anticancer drugs. We design five new bivalent Smac mimetics, which are formed by various linkers tethering two diazabicyclic cores being the IAP binding motifs. We built in silico models of the five mimetics by the TwistDock workflow and evaluated their conformational tendency, which suggests that compound 3, whose linker is n-hexylene, possess the highest binding potency among the five. After synthesis of these compounds, their ability in tumour cell growth inhibition and apoptosis induction displayed in experiments with SK-OV-3 and MDA-MB-231 cancer cell lines confirms our prediction. Among the five mimetics, compound 3 displays promising pro-apoptotic activity and deserves further optimization.

Interaction of SMAC with a survivin-derived peptide alters essential cancer hallmarks: Tumor growth, inflammation, and immunosuppression.

Second mitochondrial-derived activator of caspase (SMAC), also known as direct inhibitor of apoptosis-binding proteins with low pI (Diablo), is known as a pro-apoptotic mitochondrial protein released into the cytosol in response to apoptotic signals. We recently reported SMAC overexpression in cancers as essential for cell proliferation and tumor growth due to non-apoptotic functions, including phospholipid synthesis regulation. These functions may be associated with its interactions with partner proteins. Using a peptide array with 768 peptides derived from 11 selected SMAC-interacting proteins, we identified SMAC-interacting sequences. These SMAC-binding sequences were produced as cell-penetrating peptides targeted to the cytosol, mitochondria, or nucleus, inhibiting cell proliferation and inducing apoptosis in several cell lines. For in vivo study, a survivin/baculoviral inhibitor of apoptosis repeat-containing 5 (BIRC5)-derived peptide was selected, due to its overexpression in many cancers and its involvement in mitosis, apoptosis, autophagy, cell proliferation, inflammation, and immune responses, as a target for cancer therapy. Specifically, a SMAC-targeting survivin/BIRC5-derived peptide, given intratumorally or intravenously, strongly inhibited lung tumor growth, cell proliferation, angiogenesis, and inflammation, induced apoptosis, and remodeled the tumor microenvironment. The peptide promoted tumor infiltration of CD-8+ cells and increased cell-intrinsic programmed cell death protein 1 (PD-1) and programmed cell death ligand 1 (PD-L1) expression, resulting in cancer cell self-destruction and increased tumor cell death, preserving immune cells. Thus, targeting the interaction between the multifunctional proteins SMAC and survivin represents an innovative therapeutic cancer paradigm.

Synergistic effects of Smac mimetic APG-1387 with anti-PD-1 antibody are attributed to increased CD3 + NK1.1 + cell recruitment secondary to induction of cytokines from tumor cells.

BACKGROUND: Immune checkpoint inhibitors are approved for the treatment of various tumors, but the response rate is not satisfactory in certain malignancies. Inhibitor of apoptosis proteins (IAP) ubiquitin-E3 ligase activity is involved in the regulation of immune responses. APG-1387 is a novel second mitochondria-derived activator of caspase (Smac) mimetic IAP inhibitor. The aim of this study was to explore the synergistic effect of APG-1387 when combined with anti-PD-1 antibody in a preclinical setting. METHODS: We utilized syngeneic mouse models of ovarian cancer (ID8), colon cancer (MC38), malignant melanoma (B16), and liver cancer (Hepa1-6) to assess the combination effect of APG-1387 and anti-PD-1 antibody, including immune-related factors, tumor growth, and survival. MSD V-PLEX validated assays were used to measure in vitro and in vivo cytokine release. RESULTS: In ID8 ovarian cancer and MC38 colon cancer models, APG-1387 and anti-PD1 antibody had synergistic antitumor effects. In the MC38 model, the combination of APG-1387 and anti-PD-1 antibody significantly inhibited tumor growth (P < 0.0001) and increased the survival rate of tumor-bearing animals (P < 0.001). Moreover, we found that APG-1387 upregulated tumor-infiltrating CD3 + NK1.1 + cells by nearly 2-fold, by promoting tumor cell secretion of IL-12. Blocking IL-12 secretion abrogated the synergistic effects of APG-1387 and anti-PD-1 antibody in both MC38 and ID8 models. CONCLUSIONS: APG-1387 has the potential to turn "cold tumors" into hot ones by recruiting more CD3 + NK1.1 + cells into certain tumors. Based on these and other data, the safety and therapeutic effect of this combination will be investigated in a phase 1/2 trial in patients with advanced solid tumors or hematologic malignancies (NCT03386526).

Simultaneous XIAP and cIAP1/2 inhibition by a dimeric SMAC mimetic AZD5582 induces apoptosis in multiple myeloma.

Overexpression of inhibitor of apoptosis (IAP) proteins is associated with poor prognosis. In multiple myeloma (MM), the IAP inhibitors (IAPi), LCL161, have been evaluated in preclinical and clinical settings but are not fully effective. Among IAPs, XIAP has the strongest anti-apoptotic function with direct binding activity to caspases and cIAP1 and cIAP2 are positive regulator of NF-κB signaling. Prior IAPi such as LCL161 has high affinity to cIAP1 and cIAP2 resulting in inferior inhibiting activity against XIAP. A novel dimeric IAPi, AZD5582 (C58H78N8O8), have high binding potency to XIAP with EC50 dose of 15 nM, enabling to simultaneous inhibit XIAP and cIAP1/2. AZD5582 monotherapy showed cell growth inhibition for all MM cell lines, MM1S, RPMI8226, U266 and KMS-5 and induced apoptosis. AZD5582 further showed anti-proliferation effect under the IL-6 additional condition and inhibited JAK-STAT signaling triggered by IL-6. AZD5582 combined with carfilzomib therapy showed a synergistic effect. Enhanced apoptosis was also observed in combination therapy. Synergistic effect was further observed with other conventional therapeutics. Simultaneous XIAP and cIAP1/2 inhibition by the dimeric IAPi AZD5582 is promising. This study provides a rationale of AZD5582 as a new treatment strategy in monotherapy and in combination therapy.

SMAC Mimetics for the Treatment of Lung Carcinoma: Present Development and Future Prospects.

BACKGROUND: Uncontrolled cell growth and proliferation, which originate from lung tissue often lead to lung carcinoma and are more likely due to smoking as well as inhaled environmental toxins. It is widely recognized that tumour cells evade the ability of natural programmed death (apoptosis) and facilitates tumour progression and metastasis. Therefore investigating and targeting the apoptosis pathway is being utilized as one of the best approaches for decades. OBJECTIVE: This review describes the emergence of SMAC mimetic drugs as a treatment approach, its possibilities to synergize the response along with current limitations as well as future perspective therapy for lung cancer. METHOD: Articles were analysed using search engines and databases namely Pubmed and Scopus. RESULT: Under cancerous circumstances, the level of Inhibitor of Apoptosis Proteins (IAPs) gets elevated, which suppresses the pathway of programmed cell death, plus supports the proliferation of lung cancer. As it is a major apoptosis regulator, natural drugs that imitate the IAP antagonistic response like SMAC mimetic agents/Diablo have been identified to trigger cell death. SMAC i.e. second mitochondria activators of caspases is a molecule produced by mitochondria, stimulates apoptosis by neutralizing/inhibiting IAP and prevents its potential responsible for the activation of caspases. Various preclinical data have proven that these agents elicit the death of lung tumour cells. Apart from inducing apoptosis, these also sensitize the cancer cells toward other effective anticancer approaches like chemo, radio, or immunotherapies. There are many SMAC mimetic agents such as birinapant, BV-6, LCL161, and JP 1201, which have been identified for diagnosis as well as treatment purposes in lung cancer and are also under clinical investigation. CONCLUSION: SMAC mimetics acts in a restorative way in the prevention of lung cancer.

Design, synthesis and bioactivity evaluation of novel fusion peptides and their CPT conjugates inducing effective anti-tumor responses on HER2 positive tumors.

Human epidermal growth factor receptor 2 (HER2) represents an ideal target for antibody drug development, abnormal expression of the HER2 gene is associated with multiple tumor types. Pertuzumab, as the first monoclonal antibody inhibitor of HER2 dimerization, has been FDA-approved for HER2-positive patients. In order to enhance the activity of HER2-targeted peptide-drug conjugates (PDCs) developed based on pertuzumab, a novel class of conjugates 1-9 was designed and synthesized by fusing the N-terminal peptide sequence of the second mitochondria-derived activator of caspases (SMAC) with P1, followed by conjugation with CPT molecules. Compound 4 exhibited excellent in vitro anti-tumor activity across the three HER2-positive cell lines, comparable to the activity of CPT. Apoptosis induction assays indicated that the synergistic effect of the SMAC sequence enhanced the pro-apoptotic activity of the conjugate. Western Blot analysis and Caspase activity studies validated the mechanism through which SMAC peptides, in synergy with CPT, enhance the activity of PDCs. In vivo studies demonstrated that compound 4 possesses superior anti-tumor activity compared to CPT and can effectively mitigate potential renal toxicity associated with free SMAC peptides. In conclusion, conjugate 4 exhibited excellent anti-tumor activity both in vitro and in vivo, offering potential for further development as a novel peptide-conjugated drug.

Research Progress in the Use of Small Molecule Smac Mimetics in Combination Therapy of Cancer.

Inhibitors of Apoptosis Proteins (IAP) are inhibitors that can block programmed cell death, are expressed at high levels in various cancers, and are recognized as a therapeutic target for cancer therapy. In the past few years, several small molecule IAP protein inhibitors have been designed to mimic the endogenous IAP antagonist, but no IAP inhibitors have been approved for marketing worldwide. Previously, xevinapant has been awarded a breakthrough therapy designation by the FDA. In addition, a combination of Smac-mimetics and chemotherapeutic compounds has been reported to improve anticancer efficacy. According to the phase II clinical data, xevinapant has the potential to significantly enhance the standard therapy for patients with head and neck cancer, which is expected to be approved as an innovative therapy for cancer patients. Therefore, this paper briefly describes the mechanism of IAPs (AT-406, APG-1387, GDC- 0152, TL32711, and LCL161) as single or in combination for cancer treatment, their application status as well as the synthetic pathway, and explores the research prospects and challenges of IAPs antagonists in the tumor combination therapy, with the hope of providing strong insights into the further development of Smac mimics in tumor therapy.

Inhibitor of apoptosis proteins (IAP) inhibitor APG-1387 monotherapy or in combination with programmed cell death 1 (PD-1) inhibitor toripalimab in patients with advanced solid tumors: results from two phase I trials.

BACKGROUND: APG-1387 is a novel second mitochondrial-derived activator of caspases mimetic, small-molecule inhibitor targeting inhibitor of apoptosis proteins. We report results from two phase I trials evaluating the tolerability, safety, and antitumor activity of APG-1387 monotherapy and APG-1387 plus toripalimab [a programmed cell death 1 (PD-1) inhibitor] for advanced solid tumors. PATIENTS AND METHODS: Participants aged ≥18 years who had histologically confirmed advanced solid tumors with no appropriate standard of care (or refractory to standard care) were eligible. Patients received escalating intravenous doses of APG-1387 alone or combined with fixed-dose toripalimab (240 mg every 3 weeks) in a '3 + 3' design. Primary endpoints were dose-limiting toxicities (DLTs) and maximum tolerated dose (MTD) in the monotherapy trial, and recommended phase II dose (RP2D) in the combination therapy trial. Secondary endpoints included the pharmacokinetic and pharmacodynamic profiles and preliminary efficacy in both trials. RESULTS: In the monotherapy trial, 28 subjects were enrolled and received ≥1 treatment cycle. No DLT was reported among the 28 subjects, and the MTD was not reached. One participant (3.6%) had a grade ≥3 treatment-related adverse event (TRAE) of alanine aminotransferase elevation. In efficacy analysis of 23 participants, none achieved an objective response, and the disease control rate was 21.7%. In the combination trial, 22 subjects were enrolled and included in all analyses. There was one DLT of grade 3 lipase elevation. The MTD was not reached. Four grade ≥3 TRAEs occurred in three participants (13.6%), with the most common being lipase elevation (n = 2). The RP2D was 45 mg weekly. The objective response rate was 13.6%, with complete response achieved in one subject, and the disease control rate was 54.5%. CONCLUSIONS: APG-1387 45 mg weekly plus toripalimab was well tolerated and is recommended for further study, with preliminary clinical activity observed in study participants with advanced solid tumors.

Experimental Research on Gradation Range and Performance of SMAC13.

Stone matrix asphalt and asphalt concrete mixture with 13.2 mm nominal maximum aggregate size (named SMA13 and AC13, respectively) are widely used in the surface course of asphalt pavement in China. Generally, the pavement performance of SMA13 is superior to that of AC13, while the cost of the former is significantly higher than that of the latter. The objective of this paper was to develop a new hot mix asphalt (named SMAC13) whose performance and cost are between SMA13 and AC13. A boundary sieve size (BSS) of 2.36 mm was selected between fine and coarse aggregates. Based on the union set of aggregate gradation ranges of SMA13 and AC13, the family of gradation curves in the forms of S shapes were designed in terms of the BSS passing rate. According to the evaluation of the skeleton interlock of coarse aggregate of the gradation curve family, the aggregate gradation range of SMAC13 was determined. Also, the performance of three kinds of asphalt mixtures were compared through laboratory tests. The results indicated that SMA13 shows the best rutting resistance, followed by SMAC13 then AC13, while in terms of low-temperature performance in resistance to cracking, the sequence is SMAC13, AC13, and SMA13. The sequence of water stability is AC13, SMAC13, and SMA13. Furthermore, the cost of SMAC13 is 25% less than that of SMA13. Therefore, SMAC13 can be used as an alternative for the surface course of asphalt pavement in terms of performance and cost.

Global siRNA Screen Reveals Critical Human Host Factors of SARS-CoV-2 Multicycle Replication.

Defining the subset of cellular factors governing SARS-CoV-2 replication can provide critical insights into viral pathogenesis and identify targets for host-directed antiviral therapies. While a number of genetic screens have previously reported SARS-CoV-2 host dependency factors, these approaches relied on utilizing pooled genome-scale CRISPR libraries, which are biased towards the discovery of host proteins impacting early stages of viral replication. To identify host factors involved throughout the SARS-CoV-2 infectious cycle, we conducted an arrayed genome-scale siRNA screen. Resulting data were integrated with published datasets to reveal pathways supported by orthogonal datasets, including transcriptional regulation, epigenetic modifications, and MAPK signalling. The identified proviral host factors were mapped into the SARS-CoV-2 infectious cycle, including 27 proteins that were determined to impact assembly and release. Additionally, a subset of proteins were tested across other coronaviruses revealing 17 potential pan-coronavirus targets. Further studies illuminated a role for the heparan sulfate proteoglycan perlecan in SARS-CoV-2 viral entry, and found that inhibition of the non-canonical NF-kB pathway through targeting of BIRC2 restricts SARS-CoV-2 replication both in vitro and in vivo. These studies provide critical insight into the landscape of virus-host interactions driving SARS-CoV-2 replication as well as valuable targets for host-directed antivirals.

Adsorption and photocatalytic degradation of 2,4-dicholrophenol using surgical mask derived SMAC-Fe2O3 composite; adsorption isotherms, kinetics, thermodynamics.

Hybrid material of surgical mask activated carbon (SMAC) and Fe2O3 (SMAC-Fe2O3) composite was prepared by simple co-precipitation method and used as potential material for the remediation of 2,4-dicholrophenol (2,4-DCP). The XRD patterns exhibited the presence of SMAC and Fe2O3, FTIR spectrum showed the FeO-carbon stretching at the wavenumber from 400 to 550 cm-1. UV-Vis DRS results showed the band gap was 1.97 eV and 2.05 eV for SMAC-Fe2O3 and Fe2O3, respectively. The SEM images revealed that the Fe2O3 doped onto the fiber morphology of SMAC. The outcomes of the BET examination exhibited a surface area of 195 m2/g and a pore volume of 0.2062 cm3/g for the SMAC/Fe2O3 composite. The batch mode study shows the maximum adsorption and photocatalytic degradation efficacies which were 97% and 78%, respectively. The experimental data was studied with both linear and nonlinear adsorption isotherm and kinetics models. The nonlinear Langmuir isotherm and pseudo-second-order kinetics (PSOK) models have well fit compared with other models. The Langmuir maximum adsorption capacity (qmax) was found 161.60 mg/g. Thermodynamic analysis shows that the 2,4-DCP adsorption onto SMAC-Fe2O3 was a spontaneous and exothermic process. The PSOK assumes that the adsorption process was chemisorption. The photocatalytic degradation rate constant of 2,4-DCP was calculated using pseudo-first-order kinetics (PFOK) and the rate constant for SMAC-Fe2O3 and Fe2O3 were 0.859 × 10-2 min-1 and 0.616 × 10-2 min-1, correspondingly. In addition, the obtained composite exhibited good reusability after a few cycles. These results confirmed that SMAC-Fe2O3 composite is an effective adsorbent and photocatalyst for removing 2,4-DCP pollutants.

Effect of SMAC Gene on Sensitivity of Lung Adenocarcinoma Cells to Paclitaxel and Cell Viability Based on caspase-3/Bcl-2/Bax Signaling Pathway / 肿瘤防治研究

Objective To investigate the effect of the SMAC gene on paclitaxel sensitivity and cellular activity in lung adenocarcinoma cells based on the caspase-3/Bcl-2/Bax signaling pathway. Methods A paclitaxel-resistant cell line A549/Taxol was established for lung adenocarcinoma, and the cells were divided into four following groups: pcDNA-NC (transfected with pcDNA-NC blank vector), pcDNA-SMAC (transfected with pcDNA-SMAC vector), siRNA-NC (transfected with siRNA-NC empty virus vector), and siRNA-SMAC groups (transfected with siRNA-SMAC lentiviral vector). The SMAC mRNA expression in cells was detected by qRT-PCR; cell sensitivity was detected by MTT; cell proliferation ability was detected by cloning assay; cell invasion ability was detected by Transwell; apoptosis ability was detected by flow cytometry assay; and caspase-3, Bcl-2 and Bax protein expression in cells were detected by Western blot analysis. Results The SMAC mRNA expression was significantly lower in A549 cells compared with BEAS-2B cells (P < 0.05). The SMAC mRNA expression was significantly higher in the pcDNA-SMAC group than that in the pcDNA-NC group cells (P < 0.05). The SMAC mRNA expression was significantly lower in the cells of the siRNA-SMAC group (P < 0.05) than that in the siRNA-NC group. The SMAC mRNA expression was significantly lower in the cells of the siRNA-SMAC group (P < 0.05) than in the siRNA-NC group. Compared with the pcDNA-NC group, the cell IC50, cell clone number, cell invasion ability, and Bcl-2 protein and Bcl-2/Bax ratio were significantly lower in the pcDNA-SMAC group, the cell resistance index reversal was 2.51-fold, and the apoptosis ability and caspase-3, as well as Bax protein expression, were significantly higher (P < 0.05). Compared with the siRNA-NC group, cell IC50, cell clone number, cell invasion ability, and Bcl-2 protein and Bcl-2/Bax ratio were significantly higher in the siRNA-SMAC group, and apoptosis ability and caspase-3 and Bax protein expression were significantly lower (P < 0.05). Conclusion High expression of SMAC increases paclitaxel sensitivity, inhibits cell growth and invasion, promotes apoptosis in lung adenocarcinoma cells, and has a regulatory effect on the caspase-3/Bcl-2/Bax signaling pathway.

Anti-hepatoma effects of Smac analogue Birinapant and its related molecular mechanism / 中国应用生理学杂志

OBJECTIVE@#To investigate the effects of Birinapant on hepatocellular carcinoma cells and its related molecular mechanisms.@*METHODS@#Human hepatocellular carcinoma cells QGY-7701 were treated with 0, 1, 5, 25 and 125 nmol/L Birinapant for 24, 48 and 72 hours respectively, each experiment 3 wells.The proliferation activity of cells, the apoptosis levels, the cells nuclear type, the mitochondrial membrane potential, the transcription and expression levels of genes and the cytotoxicity of Birinapant were analyzed.At the same time, 4-week-old male BALB/C mice were randomly divided into 5 groups, with 20 mice in each group.The mice were inguinal injected with QGY-7701 cells, and then subcutaneous injected with Birinapant (concentrations ranging from 0, 1, 5, 25, 125 μg/kg) in each group after two days, once every other day.On 18 day since first Birinapant injection, 10 mice were killed in each group to weigh tumor tissue and survival time was recorded from the remaining 10 mice.The effects of Birinapant on the growth of the tumor and the survival time of tumor-bearing mice were observed.@*RESULTS@#Compared with the negative control (NC) group, the proliferation activity of QGY-7701 was inhibited significantly after Birinapant treatment and the apoptosis levels were increased significantly (<0.01).The cell mitochondrial membrane potential was decreased and the karyotype was changed (<0.01).At the same time, the transcription and expression levels of genes cellular inhibitor of apoptosis protein 1(cIAP-1), cellular inhibitor of apoptosis protein 2(cIAP-2), ras, raf, mek and erk were significantly decreased (<0.01), while the expression levels of caspase-3 and caspase-9 genes were up-regulated (<0.01).Compared with the model group (MG), the growth of the tumor was inhibited significantly and the survival time of the tumor-bearing mice was prolonged after Birinapant treatment (<0.01).@*CONCLUSIONS@#Birinapant can inhibit the expression of cIAP-1, cIAP-2 and the proteins of Ras-Raf-MEK-ERK signal pathways, so as to activate the mitochondria mediated endogenous apoptosis pathway.Birinapant shows a certain inhibitory effect on liver cancer.

Effect of α-Asarone on Esophageal Eca-109 Cell Mitochondrial Apoptosis Pathway / 医药导报

Objective To discuss the effect of α-asarone on the expression level of Cyt-c,Smac,Caspase3 mRNA and protein in human esophageal carcinoma Eca-109 cell mitochondria. Methods The Eca-109 cells were cultured in vitro,and divided into the negative control group and the α-asarone treatment groups(final concentration:25,50,100 μg·mL-1).After 48 h,the morphological changes of Eca-109 cells were observed by fluorescence inversion microscope.The total RNA of cells were extracted by TRIzol method,the expressions of Cyt-c、Smac and Caspase3 were measured by RT-PCR and Western blotting. Results After Eca-109 cells were treated with different concentrations of α-asarone for 48 h,and obvious changes in the morphology were observed,the expressions of Cyt-c,Smac and Caspase3 genes and protein were increased significantly compared to the negative control group( P<0.05). Conclusion α-asarone can induce the human Eca-109 cells apoptosis by regulating expressions of mitochondrial apoptosis pathway correlation genes such as Cyt-c,Smac and Caspase3.

Effects of the Survivin shRNA-APC double-gene on the expressions of survivin,Cytc,Smac and Caspase-9 in the colon cancer mitochondrial apoptosis pathway / 医学研究生学报

Objective Little is known about the effect of RNAi on mitochondrial apoptotic pathways. This study aims to explore the effects of the Survivin shRNA-APC double-gene on colon cancer mitochondrial apoptosis pathway-related factors survivin,cytochrome C (Cytc),second mitochondria-derived activator of caspases (Smac),and cysteine aspartic acid specific protease 9 (Caspase-9) as well as on the apoptosis of colon cancer transplanted tumor (CCTT) cells. Methods Thirty nude mice were randomly divided into five groups of equal number,Survivin shRNA-APC double-gene,survivin shRNA,APC,empty vector and blank transfection. The CCTT model was established in the nude mice by subcutaneous injection of the colon cancer cell strains stably transfected with the Survivin shRNA-APC double-gene,survivin shRNA,APC,an empty vector and HT-29,respectively,into the mid-posterior part of the left armpit of the nude mice. The rate of tumor growth inhibition was calculated by measuring the volume and weight of the CCTTs in the nude mice. The mRNA and protein expressions of survivin,Cytc,Smac and Caspase-9 in the tumor tissue were detected by real time PCR and immunohistochemistry,respectively,and the apoptosis rate of the CCTT cells was detected by TUNEL. Results The model of CCTT was successfully established in the nude mice. Com-pared with the empty vector and blank transfection groups,the mice in the double-gene,survivin shRNA and APC groups showed sig-nificantly decreased average volume and weight of the tumor tissue (P<0.05) but increased inhibition rate of its volume and weight (P<0.05). In comparison with the survivin shRNA and APC groups,the double-gene group exhibited remarkably decreased average volume and weight of the tumor tissue (P<0.05) but increased inhibition rate of its volume and weight (P<0.05). The mRNA and pro-tein expressions of survivin were significantly lower while those of Cytc,Smac and Caspase-9 markedly higher in the double-gene,sur-vivin shRNA and APC groups than in the empty vector and blank transfection groups (P<0.05),the former even lower (P<0.05) and the latter even higher in the double-gene than in the survivin shRNA and APC groups (P<0.05). The apoptosis rate of the CCTT cells was significantly increased in the double-gene ([56.78±3.04]%),survivin shRNA ([33.61±2.02]%) and APC groups ([30.16± 1.72]%) as compared with the empty vector ([10.05±0.42]%) and blank transfection groups ([9.87±0.30])% (P<0.05),even higher in the double-gene group than in the survivin shRNA and APC groups (P<0.05). Conclusion The Survivin shRNA-APC double-gene may induce apoptosis of colon cancer transplanted tumor cells by down-regulating the expression of the apoptosis inhibitor survivin,upregulating the expressions of Cytc,Smac and Caspase-9,and suppressing the growth of the colon transplanted tumor,with more significant abilities than a single gene in regulating apoptosis-related factors,inducing cell apoptosis and inhibiting the growth of the transplanted tumor.

Progress of the anti-tumor mechanisms of Smac mimics / 国际生物医学工程杂志

The tolerance of tumor cells to treatment factors is the main reason to limit the therapeutic effect.The high expression of inhibitor of apoptosis proteins (IAPs) is an important factor in the development of therapeutic resistance in tumor cells.As an effective pro-apoptotic protein,the second mitochondria-derived activator of caspase (Smac) can significantly enhance the sensitivity of tumor cells to chemoradiotherapy and promote the apoptosis of tumor cells.However,exogenous Smac protein and its active groups can not enter the tumor cells and play their functions.Therefore,the researches on Smac mimics and their functional mechanism have become the focus of attention of researchers.In this paper,the research progress of Smac mimics and their anti-tumor mechanisms were reviewed.

The proliferative inhibition and apoptosis promotion of Smac on human lens epithelial cells / 中华实验眼科杂志

Background Posterior capsular opacification (PCO) is a primary complication after extracapsular cataract extraction.The mechanism of PCO is associated with proliferation,migration and epithelialmesenchymal transition (EMT) of human lens epithelial cells (LECs).To explore the target treatment of PCO is very important.Objective This study was to investigate the biological effects of second mitochondria-derived activator of caspases (Smac) on the proliferation and apoptosis of LECs.Methods Human LECs line (HLE-B3) and Smac-overexpressed LECs line were cultured,and the cells were transfected using small interfering RNA (siRNA)-Smac3 plasmid with green fluorescent protein (GFP) for 24 hours.Different concentration of transforming growth factor-β2 (TGF-β2) (5,10,20 and 50 μg/ml) or 200 μmol/L H2O2 were added respectively into the culture medium to establish PCO model and oxidative stress model.Cell counting kit-8 (CCK-8) assay was used to compare the cell proliferative activity among PBS group,TGF-β2 group and Smac-hyperexpression +TGF-β2 group.Flow cytometry was used to evaluate the apoptotic rate of the PBS group,H2 O2 group and siRNA-Smac+H2 O2 group.The expressions of Smac,caspase-3 and proliferating cell nuclear antigen (PCNA) mRNA and their proteins in the cells were detected by real-time quantitative PCR (RT-PCR) and Western blot.Results The GFP+ cells were≥ 80％ 12 hours after siRNA-Smac3 transfection,with the optimal plasmid of siRNA-Smac3.GFP+ cell rate was (72.32 ± 2.31)％ in the siRNA-Smac3 transfection group,which was significantly higher than that in the blank plasmid group ([4.91 ±0.24] ％) (t=116.342,P＜0.001).The relevant expression levels of Smac was 35.21 ±4.11 in the Smachyperexpression group,and that in the blank plasmid group was 15.24±2.48,with a significant difference between them (t =215.47,P＜0.05).The cell viability of 20 ng/ml TGF-β2 affected PBS group,TGF-β2 group and Smachyperepression+TGF-β2 group was (98.4 ± 1.7) ％,(98.9 ± 0.1) ％ and (64.2 ± 3.1) ％,and the cell viability of Smac-hyperepression+TGF-β2 group was significantly lower in the Smac-hyperepression+TGF-β2 group than that in the TGF-β2 group (P＜0.05).The apoptotic rate in the PBS group,H2 O2 group and siRNA-Smac+H2 O2 group were (2.9 ± 1.2) ％,(45.1 ±4.5) ％ and (27.5 ± 1.8) ％,and the apoptotic rate was evidently lower in the siRNA-Smac +H2O2 group than that in the H2O2 group (P＜0.05).RT-PCR results showed that the expression levels of caspase-3 mRNA in PBS group,H2 O2 group and siRNA-Smac + H2 O2 group were 0.321 ± 0.103,0.715 ± 0.112 and 0.479 ±0.209,respectively.Compared with the H2 O2 group,the relative expression level of caspase-3 mRNA in siRNA-Smac+ H2O2 group was significantly decreased,the difference was statistically significant (P＜ 0.05).The PCNA mRNA expression levels in PBS group,TGF-β2 group and Smac-hyperepression+TGF-β2 group were 0.299±0.013,0.645± 0.102 and 0.490±0.209,respectively.Western blot results showed that the relative expression of caspase-3 protein in siRNA-Smac+H2O2 group and H2O2 group was 0.712±0.012 and 0.973±0.051,with significant difference between the two groups (t =132.52,P＜0.05).The relative expression of PCNA protein in Smac-hyperepression+TGF-β2 group was 0.782±0.212,which was lower than 1.126±0.251 in the TGF-β2 group (P＜0.05).Conclusions Smac may prevent and treat PCO by inhibiting the proliferation and promoting apoptosis of human LECs.

Effect and mechanism of all-trans retinoic acid on cyclosporin-induced proliferation and apoptosis of glomerular mesangial cells / 器官移植

Objective To investigate the effect and mechanism of all-trans retinoic acid (ATRA) on the cyclosporin (CsA)-induced proliferation and apoptosis of glomerular mesangial cells in rat models. Methods The glomerular mesangial cells induced by different doses of CsA were treated with different doses of ATRA. MTT assay was carried out to detect cell proliferation. Hoechst 33258 fluorescent staining was adopted to observe the morphology of the apoptotic cells. Flow cytometry was conducted to detect the cellular apoptosis rate. Immunofluorescent staining was employed to quantitatively measure the expression level of mitochondria-derived pro-apoptotic Smac protein. Results Compared with the control group, administration of CsA at a dose of 0.5 μg/mL and above could suppress cellular proliferation, and use of CsA at a dose of 1.0 μg/mL and above could induce cellular apoptosis. The expression level of Smac protein was significantly up-regulated by CsA administration with a dose and time dependence (all P<0.05).Compared with the CsA group, combined administration of CsA and ATRA exerted a more significant inhibitory effect on cellular proliferation. Supplement of ATRA could significantly inhibit glomerular mesangial cellular apoptosis induced by CsA and down-regulate the expression of Smac protein with a dose dependence (both P<0.05). Conclusions CsA can inhibit cellular proliferation, induce cellular apoptosis and up-regulate the expression of Smac protein of glomerular mesangial cells. ATRA is capable of suppressing glomerular mesangial cellular apoptosis induced by CsA, which is probably mediated by the Smac signaling pathway.

Is there something else besides the proapoptotic AVPI-segment in the Smac/DIABLO protein? / ¿Existe algo adicional al segmento pro-apoptótico AVPI de la proteína Smac/DIABLO?

Abstract: In mammals, apoptosis is the main mechanism to eliminate unwanted cells, securing tissue homeostasis and consequently maintaining the health in the organism. Classically, apoptosis culminates with the activation of caspases, which are enzymes that display cysteine protease activity to degrade specific substrates implied in essential cellular processes. This process is highly regulated. A key regulation mechanism is mediated by the Inhibitor of Apoptosis Proteins (IAPs) family members, which inhibit the activated forms of caspases through physical interaction with them. Smac/DIABLO, a mitochondrial protein that is translocated to the cytoplasm in apoptotic conditions, derepresses the IAP-mediated caspase inhibition through physical interaction with IAPs. The first four amino acids (AVPI) of Smac/DIABLO mediate the interaction with IAPs and subsequent apoptosis induction. This interaction has lead to the creation of small molecules mimicking the AVPI segment for potential anticancer therapy. Nevertheless, several studies have pointed out the existence of AVPI-independent functions of Smac/DIABLO. The aim of this review was to provide a landscape of these underestimated AVPI-independent biological functions that have been observed using different approaches, such as the study of endogenous splice variant isoforms and truncated and mutated artificial proteins.

Resumen: La apoptosis es uno de los principales mecanismos en los mamíferos para eliminar células no deseadas, asegurando la homeostasis de los tejidos y, consecuentemente, la salud de los mismos. De forma clásica, la apoptosis finaliza con la activación de las caspasas, enzimas que despliegan actividad de proteasas de cisteína, involucradas en la degradación de sustratos específicos implicados en procesos celulares esenciales. El proceso apoptótico se encuentra altamente regulado. Un mecanismo de regulación es el mediado por los miembros de la familia de las Proteínas Inhibidoras de la Apoptosis (PIA), las cuales inhiben a las formas activas de las caspasas a través de la interacción física con estas. Smac/DIABLO, proteína mitocondrial que es translocada al citoplasma en condiciones apoptóticas, antagoniza la inhibición de las caspasas mediante su interacción física con las PIA. Los cuatro primeros aminoácidos (AVPI) de Smac/DIABLO intervienen en su asociación con las PIA y la subsecuente inducción apoptótica. Esto ha guiado a la generación de pequeñas moléculas miméticas del segmento AVPI para el uso potencial como una terapia anti-cancerígena. Sin embargo, varios estudios han indicado la presencia de funciones en Smac/DIABLO independientes del AVPI. El objetivo de esta revisión fue proporcionar un panorama de estas funciones biológicas desestimadas —independientes al AVPI— las cuales se han observado utilizando diferentes aproximaciones, como el estudio de las isoformas generadas por el procesamiento alternativo del gen y la síntesis de proteínas artificialmente mutadas.

Anti-tumor research targeting IAPs / 中国药理学通报

Apoptosis inhibitors ( inhibitor of apoptosis proteins, IAPs) are a class of highly conserved apoptotic endogenous anti-cytokine family, primarily by inhibiting caspase activity and par-ticipation in regulation of nuclear factor NF-κB inhibition of ap-optosis. caspases cascade of protease activation is a central part of the apoptotic process, Bcl-2 family proteins and IAPs family proteins are the main controlling factors. In recent years, we found that abnormal expression of some IAPs members is closely associated with the tumor, a potential target for cancer therapy. Therefore, this paper reviews the major protein associated with IAPs family and anti-tumor research targeting IAPs.