XIAP Protein Expression Research Articles

MCPIP1 Elicits a Therapeutic Effect on Cervical Cancer by Facilitating XIAP mRNA Decay via Its Endoribonuclease Activity.

Cervical cancer is the fourth most common malignancy in women globally. Chemotherapies, targeted therapies, and immunotherapies in the treatment of cervical cancer are usually accompanied by effective and adverse effects. Therefore, finding other efficient and accurate molecular targets remains essential to improve the treatment benefits of cervical cancer patients. MCPIP1 (monocyte chemoattractant protein-induced protein 1) is a kind of endonuclease with a CCCH zinc finger domain and a PilT-N-terminal (PIN) domain, and its function in cervical cancer is unknown. We found that MCPIP1 inhibits cell proliferation and promotes cell apoptosis of cervical cancer. Additionally, MCPIP1 suppresses mRNA and protein expression of the apoptotic inhibitor XIAP by decreasing its mRNA stability. Mechanically, MCPIP1 binds to the XIAP mRNA via its CCCH zinc finger domain and degrades the XIAP mRNA via the endonuclease activity coming from its PIN domain. Our study clarifies that MCPIP1 promotes cervical cancer cell apoptosis by suppressing the expression of XIAP, thereby impeding cervical cancer progression. Moreover, targeted delivery of MCPIP1 with engineered Salmonella typhimurium leads to tumor growth retardation in the HeLa xenograft tumor model in mice. Therefore, our study may provide a theoretical basis for formulating clinical treatment strategies for cervical cancer.

Effects of Corchorusoside C on NF-κB and PARP-1 Molecular Targets and Toxicity Profile in Zebrafish

The present study aims to continue the study of corchorusoside C (1), a cardenolide isolated from Streptocaulon juventas, as a potential anticancer agent. A mechanistic study was pursued in a zebrafish model and in DU-145 prostate cancer cells to investigate the selectivity of 1 towards NF-κB and PARP-1 pathway elements. Compound 1 was found to inhibit the expression of IKKα and NF-κB p65 in TNF-α induced zebrafish and inhibit the expression of NIK in vitro. The protein expression levels of XRCC-1 were increased and p53 decreased in DU-145 cells. XIAP protein expression was initially decreased after treatment with 1, followed by an increase in expression at doses higher than the IC50 value. The activity of caspase-1 and the protein expression levels of IL-18 were both decreased following treatment of 1. The binding interactions for 1 to NIK, XRCC-1, p53, XIAP, and caspase-1 proteins were explored in molecular docking studies. Additionally, the toxicity profile of 1 in zebrafish was favorable in comparison to its analog digoxin and other anticancer drugs at the same MTD in zebrafish. Overall, 1 targets the noncanconical NF-κB pathway in vivo and in vitro, and is well tolerated in zebrafish supporting its potential in the treatment of prostate cancer.

Overexpression of XIAP inhibits cisplatin-induced hair cell loss.

Cisplatin is a platinum-containing drug with ototoxicity commonly used clinically and has significant efficacy against a variety of solid tumors. One of the most important mechanisms of ototoxicity is that cisplatin induces apoptosis of hair cells. According to relevant literature, X-linked inhibitor of apoptosis protein (XIAP, anti-apoptotic protein) could inhibit the apoptotic pathway. We hypothesized that this protein might protect cochlear hair cells from cisplatin-induced injury. To figure it out, we treated cochlea of normal mice with various concentrations of cisplatin to observe the response and morphology of hair cells and determine a reasonable concentration. Next, Western Blot and quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) experiments were conducted to make an investigation about the expression of XIAP protein and mRNA. In addition, we constructed and identified XIAP overexpressing mice. Finally, we treated cochlear tissues of normal and overexpressing mice with cisplatin to investigate the cyto-protection of XIAP on hair cells, respectively. It was found that 50μmol/L cisplatin resulted in significant loss and disorganization of hair cells, while simultaneously downregulating the protein and mRNA of XIAP. In XIAP overexpressing mice, the loss and disorganization of hair cells were significantly lessened. These results showed that XIAP can lessen cisplatin-induced hair cell loss and play a role in otoprotection.

Knockdown of circ-FURIN suppresses the proliferation and induces apoptosis of granular cells in polycystic ovary syndrome via miR-195-5p/BCL2 axis

BackgroundPolycystic ovary syndrome (PCOS) is an endocrine disease that increases the risk of infertility. Circular RNAs (circRNAs) play important roles in regulating the biological processes of PCOS. Our study was designed to explore the function of circ-FURIN in PCOS.MethodsCirc-FURIN expression was detected using RT-qPCR. The protein expression of AVEN, BCL2, XIAP and AREL1 was measured using western blot. Dual-luciferase reporter and RNA pull-down assays were applied to clarify the interaction between miR-195-5p and circ-FURIN or BCL2. Functionally, cell proliferation was assessed by MTT and colony formation assays. Cell apoptosis was analyzed by flow cytometry.ResultsCirc-FURIN was upregulated in PCOS patients and granular cells (GCs). Knockdown of circ-FURIN inhibited cell proliferation and promoted apoptosis of KGN cells, along with the increased expression of caspase-3 and Bax and the decreased levels of p-PI3K. Gene ontology (GO) analysis indicated circ-FURIN is associated with apoptotic signaling pathway and cell death. Subsequently, BCL2 expression was elevated in patients with PCOS and positively regulated by circ-FURIN. Furthermore, circ-FURIN was served as a sponge of miR-195-5p to directly target to BCL2. The levels of miR-195-5p were reduced in PCOS and KGN cells. Knockdown of circ-FURIN decreased the expression of BCL2, which was abolished by miR-195-5p inhibitor. At last, rescue experiments revealed that overexpression of BCL2 reversed the effects of circ-FURIN knockdown on cell proliferation and apoptosis of KGN cells.ConclusionsLoss of circ-FURIN alleviated the development of PCOS via miR-195-5p/BCL2 axis. Circ-FURIN may be the novel biomarker for PCOS.

Esculetin inhibits endometrial cancer proliferation and promotes apoptosis via hnRNPA1 to downregulate BCLXL and XIAP.

Endometrial cancer represents one of the most common gynecological tumors in the world. Advanced and relapsed patients rely on drug therapy. Therefore, it is extremely important to seek more effective targeted drugs. This study found that esculetin has an anti-tumor effect on endometrial cancer through cellular proliferation and apoptosis. At the same time, its anti-tumor effect has also been verified in human endometrial cancer xenograft models in nude mice. Western blot results showed that BCLXL, XIAP, and pAKT protein expression level were down-regulated. A pulldown experiment and LC-MS/MS analysis technology revealed that esculetin targets the hnRNPA1 protein. Cellular proliferation experiments following si-hnRNPA1 transfection verified the tumor-promoting effect of hnRNPA1 in endometrial cancer cells. Nuclear and cytoplasmic separation experiment demonstrated esculetin affecting the export of the hnRNPA1/mRNA complex from the nucleus into the cytoplasm. Thus, esculetin targets hnRNPA1, thereby downregulates BCLXL and XIAP mRNA transcription and translation, resulting in apoptosis and an arrest in proliferation.

MicroRNA-375-3p is implicated in carotid artery stenosis by promoting the cell proliferation and migration of vascular smooth muscle cells

BackgroundAtherosclerosis is the main cause of carotid artery stenosis (CAS) which mostly occurs in the elderly. In this paper, the expression level of miR-375-3p in asymptomatic CAS patients and its diagnostic value for asymptomatic CAS were investigated, and the effects of miR-375-3p on the cell proliferation and migration of vascular smooth muscle cells (VSMCs) was further explored.Methods 98 healthy subjects and 101 asymptomatic CAS patients were participated in this study. qRT-PCR was used to measure the expression level of serum miR-375-3p, and the ROC curve was established to evaluate the predictive value of miR-375-3p for asymptomatic CAS. After transfection with miR-375-3p mimic or inhibitor in vitro, cell proliferation and migration were detected by CCK-8 assay, colony formation assay, and Transwell assay, respectively. The levels of TNF-α, IL-1β, IL-6 were detected by ELISA. Western blot was used to detect the protein expression of XIAP. Finally, luciferase reporter gene assay was applied to assess the interaction of miR-375-3p with target genes.ResultsThe expression level of serum miR-375-3p in asymptomatic CAS patients was significantly higher than that in healthy controls, and the AUC value of ROC curve was 0.888. The sensitivity and specificity were 80.2 and 86.7%, respectively, indicating that miR-375-3p had high diagnostic value for asymptomatic CAS. In vitro cell experiments showed that up-regulation of miR-375-3p significantly promoted the proliferation and migration of VSMCs, and also promoted the generation of inflammatory factors and phenotypic transformation of VSMCs. Luciferase reporter gene assay confirmed that XIAP was a target gene of miR-375-3p and was negatively regulated by miR-375-3p.ConclusionsIn this study, miR-375-3p may have a clinical diagnostic value for asymptomatic CAS patients which need further validation. Increased miR-375-3p levels in CAS may be associated with increased proliferation and migration of VSMCs via downregulation of the apoptosis inducing gene XIAP.

Apoptotic activities of brusatol in human non-small cell lung cancer cells: Involvement of ROS-mediated mitochondrial-dependent pathway and inhibition of Nrf2-mediated antioxidant response

Brusatol occurs as a characteristic bioactive principle of Brucea javanica (L.) Merr., a traditional medicinal herb frequently employed to tackle cancer in China. This work endeavored to unravel the potential anti-cancer activity and action mechanism of brusatol against non-small cell lung cancer (NSCLC) cell lines. The findings indicated that brusatol remarkably inhibited the growth of wild-type NSCLC cell lines (A549 and H1650) and epidermal growth factor receptor-mutant cell lines (PC9 and HCC827) in a dose- and time-related fashion, and profoundly inhibited the clonogenic capability and migratory capacity of PC9 cells. Treatment with brusatol resulted in significant apoptosis in PC9 cells, as evidenced by Hoechst 33342 staining and flow cytometric analysis. The apoptotic effect was closely related to induction of G0-G1 cell cycle arrest, stimulation of reactive oxygen species (ROS) and malondialdehyde, decrease of glutathione levels and disruption of mitochondrial membrane potential. Furthermore, pretreatment with N-acetylcysteine, a typical ROS scavenger, markedly ameliorated the brusatol-induced inhibition of PC9 cells. Western blotting assay indicated that brusatol pronouncedly suppressed the expression levels of mitochondrial apoptotic pathway-associated proteins Bcl-2 and Bcl-xl, accentuated the expression of Bax and Bak, and upregulated the protein expression of XIAP, cleaved caspase-3/pro caspase-3, cleaved caspase-8/pro caspase-8, and cleaved PARP/total PARP. In addition, brusatol significantly suppressed the expression of Nrf2 and HO-1, and abrogated tBHQ-induced Nrf2 activation. Combinational administration of brusatol with four chemotherapeutic agents exhibited marked synergetic effect on PC9 cells. Together, the inhibition of PC9 cells proliferation by brusatol might be intimately associated with the modulation of ROS-mediated mitochondrial-dependent pathway and inhibition of Nrf2-mediated antioxidant response. This novel insight might provide further evidence to buttress the antineoplastic efficacy of B. javanica, and support a role for brusatol as a promising anti-cancer candidate or adjuvant to current chemotherapeutic medication in the therapy of EGFR-mutant NSCLC.

The Inhibitory Effect of Cordycepin on the Proliferation of MCF-7 Breast Cancer Cells, and its Mechanism: An Investigation Using Network Pharmacology-Based Analysis.

We determined the lipid-lowering effect of a new strain of the lactic acid bacteria Lactobacillus plantarum CQPC02 (LP-CQPC02), from Sichuan pickled cabbages, using an in vivo animal model. A high-fat diet was used to generate obese mice. The effect of LP-CQPC02 was measured using serum parameters and tissues collected from the mice. Obese mice treated with LP-CQPC02 had a lower organ index for liver, epididymal fat, and perirenal fat, and lower levels of aminotransferase (AST), alanine aminotransferase (ALT), triglyceride (TG), and total cholesterol (TC), and low density lipoprotein cholesterol (LDL-C) but higher levels of high density lipoprotein cholesterol (HDL-C) in the serum and liver. LP-CQPC02-treated obese mice also had lower serum levels of the cytokines tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), interleukin 6 (IL-6), and interleukin 1 beta (IL-1β), and higher levels of interleukin 4 (IL-4) and interleukin 10 (IL-10). LP-CQPC02 treatment lessened the obesity-associated pathological changes in the liver and epididymal adipose tissue and reduced adipocyte enlargement. The quantitative PCR (qPCR) and Western blot results showed that LP-CQPC02 treatment up-regulated mRNA and protein expression of lipoprotein lipase (LPL), peroxisome proliferator-activated receptor-alpha (PPAR-α), cholesterol 7 alpha-hydroxylase (CYP7A1), and carnitine palmitoyltransferase 1 (CPT1), but down-regulated peroxisome proliferator-activated receptor-gamma (PPAR-γ) and CCAAT enhancer-binding protein alpha (C/EBP-α) expression in the liver and epididymal adipose tissue. LP-CQPC02 effectively inhibited high-fat diet-induced obesity. The effects of LP-CQPC02 are comparable to the drug l-carnitine but superior to Lactobacillus delbruechii subsp. bulgaricus (LDSB), which is commonly used in the dairy industry. LP-CQPC02 is a potentially useful, high-quality probiotic strain.

N-end rule pathway inhibitor sensitizes cancer cells to antineoplastic agents by regulating XIAP and RAD21 protein expression.

Anticancer drugs exert their effects on cancer cells by deregulating many pathways linked to cell cycle, apoptosis, etc. but cancer cells gradually become resistive against anticancer drugs, thereby necessitating the development of newer generation anticancer molecules. N-end rule pathway has been shown to be involved in the degradation of many cell cycle and apoptosis-related proteins. However, the involvements of this pathway in cancer are not well established. Recently, we developed a non-peptide-based N-end rule pathway inhibitor, RF-C11 for type 1 and 2 recognition domains of E3 ubiquitin ligases. The inhibitor significantly increased the half-life of potential N-degrons leading to significant physiological changes in vivo. We hypothesized RF-C11 may be used to decipher the N-end rule pathway's role in cancer towards the development of anticancer therapeutics. In this study, we showed that RF-C11, barring noncancer cells, significantly sensitizes cancer cells towards different anticancer agents tested. We further find that the profound cellular sensitization to anticancer drugs was affected by (a) downregulation of X-linked inhibitor of apoptosis protein, an antiapoptotic protein and (b) by stabilization of RAD21, and thereby inhibiting metaphase to anaphase promotion. The study shows that RF-C11 or its analogs may be used as a novel additive in combination therapy against cancer.

Suppression of STAT3 Phosphorylation and RelA/p65 Acetylation Mediated by MicroRNA134 Plays a Pivotal Role in the Apoptotic Effect of Lambertianic Acid.

As p300-mediated RelA/p65 hyperacetylation by signal transducers and activators of transcription 3 (STAT3) is critical for NF-κB activation, in the current study, the apoptotic mechanism of lambertianic acid (LA) was explored in relation to STAT3 phosphorylation and RelA/p65 acetylation in MCF-7, DU145, PC-3, and MDA-MB-453 cells. LA significantly increased the cytotoxicity, sub G 1 population, and the cleavage of poly (ADP-ribose) polymerase (PARP) in MDA-MB-453 or PC-3 cells (STAT3 mutant), more than in the MCF-7 or DU145 cells (STAT3 wild). Consistently, LA inhibited the phosphorylation of STAT3 and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and disrupted the interaction between p-STAT3, p300, NF-κB, and RelA/p65 acetylation (Ac-RelA/p65) in the MCF-7 and DU145 cells. Also, LA reduced the nuclear translocation of STAT3 and NF-κB via their colocalization, and also suppressed the protein expression of XIAP, survivin, Bcl-2, Bcl-xL, vascular endothelial growth factor (VEGF), Cox-2, c-Myc and mRNA expression of interleukin 6 (IL-6), and tumor necrosis factor-α (TNF-α) in MCF-7 cells. Conversely, IL-6 blocked the ability of LA to suppress the cytotoxicity and PARP cleavage, while the depletion of STAT3 or p300 enhanced the PARP cleavage of LA in the MCF-7 cells. Notably, LA upregulated the level of miRNA134 and so miRNA134 mimic attenuated the expression of pro-PARP, p-STAT3, and Ac-RelA, while the miRNA134 inhibitor reversed the ability of LA to reduce the expression of Ac-RelA and pro-PARP in MCF-7 cells. Overall, these findings suggest that LA induced apoptosis via the miRNA-134 mediated inhibition of STAT3 and RelA/p65 acetylation.

Urolithin A induces prostate cancer cell death in p53-dependent and in p53-independent manner.

Pomegranate and walnuts are widely consumed dietary sources and contain several bioactive compounds, including the ellagitannins (ETs). ETs are polyphenols that are metabolized in the gut microbiota to urolithin A (UA). p53 is a tumor suppressor that lost its activity through MDM2 activation in about half cancers. The purpose of this study was to investigate the influence of UA on the p53-MDM2 interaction pathway in prostate cancer cell lines. Three human prostate cancer cell lines were used that harbor different p53 genotypes; LNCaP (p53+/+), 22RV1(p53-/+) and PC3 (p53-/-). Cell viability was determined by CellTiter-Glo Luminescent assay. Apoptosis was confirmed by measuring annexin V by flow cytometry. The expression of p53, its target proteins, and apoptotic markers were measured by western blotting. Real-time qPCR was used to measure the gene expression of p21, a main target gene of p53. Co-immunoprecipitation-immunoblotting was used to assess the inhibition of interactions between p53 and MDM2 and to assess the effect of UA on MDM2-mediated p53 polyubiquitination. We found UA inhibited CaP cells' viability and induced apoptosis. For 22RV1 and LNCaP, we found UA increased p53 protein expression and its main target protein, p21, and MDM2, forming an autoregulatory feedback loop. In addition, UA increased the p53 proapoptotic proteins PUMA and NOXA. Moreover, UA inhibited the interaction between p53 and MDM2 and inhibited MDM2-mediated p53 polyubiquitination. UA downregulated MDM2 and XIAP protein expression in PC3 cells and upregulated p21 and p14ARF in a p53-independent manner. The influencing of UA on p53-MDM2 pathway may partly contribute to its anticancer effect.

Effects of miR-181a targeting XIAP gene on apoptosis of cardiomyocytes induced by hypoxia/reoxygenation and its mechanism.

To investigate the effect of miR-181a targeting XIAP gene on the apoptosis of cardiomyocytes induced by hypoxia/reoxygenation (H/R) and its mechanism. The primary cultured cardiomyocytes were treated with hypoxia for 3 hours and reoxygenation for 4 hours to construct H/R cell model. The expression of miR-181a and XIAP messenger RNA in cardiomyocytes was detected by reverse-transcription polymerase chain reaction, and the expression of XIAP protein in cardiomyocytes was detected by Western blot analysis. H/R cardiomyocytes with low expression of miR-181a and overexpression of XIAP were constructed, and the effects of low expression of miR-181a and upregulation of XIAP on cardiomyocyte apoptosis were detected by flow cytometry. A dual luciferase reporter assay was used to detect the target relationship between miR-181a and XIAP. Further, H/R myocardial cells with low XIAP expression were constructed to observe the effect of downregulation of XIAP expression on apoptosis of myocardial cells with low expression of microarray-181a. The expression of apoptosis-related proteins Bax and Bcl-2 in myocardial cells was detected by Western blot analysis. After H/R treatment, the expression of microRNAs-181a was high but that of XIAP was low. The apoptosis of cardiomyocytes could be inhibited by both the low expression of miR-181a and the upregulation of XIAP. The results of dual luciferase reporter gene showed that XIAP was a potential target gene for miR-181a. The inhibitory effect of low expression of miR-181a on myocardial apoptosis could be reversed and the inhibitory effect of low expression of miR-181a on Bax protein expression and the promotion of Bcl-2 protein expression could be reversed by the downregulation of XIAP. MiR-181a can inhibit the apoptosis of hypoxic-reoxygenated cardiomyocytes by targeting XIAP to downregulate Bax and upregulate Bcl expression.

Synergistic combination of flavopiridol and carfilzomib targets commonly dysregulated pathways in adrenocortical carcinoma and has biomarkers of response.

Drug repurposing is an effective approach to identify active drugs with known toxicity profiles for rare cancers such as ACC. The objective of this study was to determine the anticancer activity of combination treatment for ACC from previously identified candidate agents using quantitative high-throughput screening (qHTS). In this study, we evaluated the anticancer activity of flavopiridol and carfilzomib in three ACC cell lines in vitro and in vivo. Human ACC samples were analyzed for drug-target analysis, and cancer-related pathway arrays were used to identify biomarkers of treatment response. Because flavopiridol is a potent cyclin-dependent kinase (CDK) inhibitor, we found significantly higher CDK1 and CDK2 mRNA expression in three independent cohorts human ACC (p<0.01) and CDK1 protein by immunohistochemistry (p<0.01) in human ACC samples. In vitro treatment with flavopiridol and carfilzomib in all three ACC cell lines resulted in a dose-dependent, anti-proliferative effect, and the combination had synergistic activity as well as in three-dimensional tumor spheroids. We observed increased G2M cell-cycle arrest and apoptosis with combination treatment compared to other groups in vitro. The combination treatment decreased XIAP protein expression in ACC cell lines. Mice with human ACC xenografts treated with flavopiridol and carfilzomib had significantly lower tumor burden, compared to other groups (p<0.05). We observed increased cleaved-caspase expression and decreased XIAP in tumor xenografts of mice treated with combined agents. Our preclinical data supports the evaluation of combination therapy with flavopiridol and carfilzomib in patients with advanced ACC.

Embelin Reverses the Multi-drug Resistance of K562/D to Daunorubicin Independently of P-gp and MDR1 mRNA

To investigate the mechanism of reversing drug resistance of K562/D cells to daunorubicin by Embelin and its relationship with P-gp and MDR1 mRNA. MTT assay was used to detect and compare the cell proliferation rate of treating with DNR alone and DNR combined with Embelin. Flow cytometry with Annexin V-FITC/PI double staining was used to detect cell apoptosis rate, Western blot was used to detect the expression of XIAP,Caspase-3,BCL-2,BAX and P-gp of K562/D cells after using DNR alone and combining with Embelin. Quantitative real-time PCR was used to detect XIAP,BCL-2,BAX and MDR1 mRNA. The IC50 of K562 and K562/D cells treated with DNR for 24 h were 2.177 µg/ml and 69.43 µg/ml, respectively. The drug-resistance index was 31.89; The proliferation inhibition rates of K562/D cells treated with Embelin of 3, 10, 30, 100 and 300 µg/ml for 24 h were 2.70%±1.08%, 10.92%±4.89%, 28.13%±2.09%, 36.56%±3.24% and 43.59%±1.16%; The proliferation inhibition rates of K562/D cells treated with DNR of 0.1, 1, 10 and 100 µg/ml combined with 10 µg/ml Embelin for 24 h were 31.92%±3.29%, 49.57%±6.87%, 55.16%±0.78% and 71.94%±3.89%. The IC50 was 2.11 µg/ml respectively. The reverse index was 32.91. The apoptosis rates of K562/D cells treated with 0.1 µg/ml DNR alone or combined with Embelin of 10 µg/ml and 30 µg/ml for 24 h were 12.06%±0.95%, 27.54%±0.59% and 39.59%±1.57%, respectively. The results of Western blot showed that after combination of DNR with Embelin, the expression of Caspase-3 was significantly down-regulated (P<0.05), moreover, the prolifiration inhibition effect of drug combination on cells could be countreacted by Z-VAD-FMK, at the same time the expression of XIAP and BCL-2 protein was significantly down-regulated(P<0.05), the expression of BAX protein was significantly up-regulated(P<0.05), while there was no change of P-gp expression later (P<0.05). The results of RT-PCR showed that after combination of DNR with Embelin, expression of XIAP and BCL-2 mRNA was significantly down-regulated(P<0.05), expression of BAX mRNA was significantly up-regulated(P<0.05), while there was no obvious change of MDR1 mRNA expression(P>0.05). The down-regulation of XIAP contributes to enhance the effect of DNR on K562/D cells, the mechanism of Embelin-reversing the drug-resistence of K562/D cells to DNR does not relate with P-gp and MDR1 mRNA.

Mouse Lung Fibroblast Resistance to Fas-Mediated Apoptosis Is Dependent on the Baculoviral Inhibitor of Apoptosis Protein 4 and the Cellular FLICE-Inhibitory Protein.

A characteristic feature of idiopathic pulmonary fibrosis (IPF) is accumulation of apoptotic resistant fibroblasts/myofibroblasts in the fibroblastic foci. As caveolin (Cav)-null mice develop pulmonary fibrosis (PF), we hypothesized that the participating fibroblasts display an apoptosis-resistant phenotype. To test this hypothesis and identify the molecular mechanisms involved we isolated lung fibroblasts from Cav-null mice and examined the expression of several inhibitors of apoptosis (IAPs), of c-FLIP, of Bcl-2 proteins and of the death receptor CD95/Fas. We found significant increase in XIAP and c-FLIP constitutive protein expression with no alteration of Bcl-2 and lower levels of CD95/Fas. The isolated fibroblasts were then treated with the CD95/Fas ligand (FasL) to induce apoptosis. While the morphological and biochemical alterations induced by FasL were similar in wild-type (wt) and Cav-null mouse lung fibroblasts, the time course and the extent of the alterations were greater in the Cav-null fibroblasts. Several salient features of Cav-null fibroblasts response such as loss of membrane potential, fragmentation of the mitochondrial continuum concurrent with caspase-8 activation, and subsequent Bid cleavage, prior to caspase-3 activation were detected. Furthermore, M30 antigen formation, phosphatidylserine expression and DNA fragmentation were caspase-3 dependent. SiRNA-mediated silencing of XIAP and c-FLIP, individually or combined, enhanced the sensitivity of lung fibroblasts to FasL-induced apoptosis. Pharmacological inhibition of Bcl-2 had no effect. Together our findings support a mechanism in which CD95/Fas engagement activates caspase-8, inducing mitochondrial apoptosis through Bid cleavage. XIAP and c-FLIP fine tune this process in a cell-type specific manner.

Effects of LCL161, a Smac mimetic on the proliferation and apoptosis in hepatocellular carcinoma cells

To investigate the effects of LCL161, a Smac mimetic, on the proliferation and apoptosis in hepatocellular carcinoma cells and the underlying mechanisms. The effect of LCL161 on the cell viability of HepG2 and SMMC7721 cells was measured by MTT assay. The effect of LCL161 at lower concentrations on the proliferation in hepatocellular carcinoma (HCC) cells was detected by colony formation assay. Apoptosis was assessed by flow cytometry with PI staining. The mitochondrial membrane potential was measured by JC-1 staining. The expression of PARP, p-Akt, cIAP1 and XIAP protein was analyzed by Western blot. LCL161 displayed notable antiproliferative activity on HCC cells at the concentrations of 1-16 μmol/L (P<0.01), with IC50 values of 4.3 and 4.9 μmol/L for HepG2 and SMMC7721 cells, respectively, after treatment for 48 h. LCL161 at lower concentrations obviously inhibited the colony formation of HCC cells. LCL161 induced significant apoptosis in HCC cells (P<0.01), and resulted in the apoptotic rate at (1.5±0.8)% or (1.8±0.6)% , (15.2±2.8)% or (12.2±2.4)%, (28.7±3.0)% or (22.4±2.7)%, (34.6±2.3)% or (30.2±2.4)% for HepG2 cells or SMMC7721 cells at the concentration of 0, 2, 4 or 8 μmol/L, respectively. The result of JC-1 staining indicated that the mitochondrial membrane potential of HCC cells was reduced by LCL161. In addition, LCL161 promoted the cleavage of PARP, down-regulated the protein expression of p-Akt, and degraded cIAP1. LCL161 possesses significant anti-proliferative activity and pro-apoptotic action in HepG2 and SMMC7721 cells, which might be correlated with reduction in mitochondrial membrane potential, down-regulation of p-Akt and degradation of cIAP1.

Silver nanoparticles induce irremediable endoplasmic reticulum stress leading to unfolded protein response dependent apoptosis in breast cancer cells.

Nowadays, silver nanoparticles (AgNP) are widely used in the medical field mainly for their antibacterial properties. Although some studies report a cytotoxic activity of the particles, the mechanisms involved in AgNP-induced cell death remain to be determined. Herein, we report that AgNP of 2 (AgNP2) and 15nm (AgNP15) induce apoptosis in human MCF-7 and T-47D breast cancer cells. Treatment with AgNP2 and AgNP15 led to accumulation and aggregation of misfolded proteins causing an endoplasmic reticulum (ER) stress and activating the unfolded protein response (UPR). The three main ER sensors, PERK, IRE-1α and ATF-6, were rapidly activated in response to AgNP2 and AgNP15. Although Grp78 levels remained unchanged, AgNP2 and AgNP15 induced upregulation of the transcription factors ATF-4 and GADD153/CHOP. Moreover, the initiating caspase-9 and the effector caspase-7 were activated in response to these NPs. The expression levels of the pro-apoptotic BIM and BAD proteins remained unchanged. In contrast, a downregulation of Mcl-1 and xIAP protein expression as well as a processing of PARP were observed. Pharmacological inhibition of PERK kinase and IRE-1 endonuclease activities, as well as inhibition of ER-stress, partially protected cells from AgNP2- and AgNP15-induced apoptosis. Of note, the non-cancerous MCF-10A cells were more resistant to both AgNP2 and AgNP15 when compared to MCF-7 and T-47D cell lines. Taken together, our results demonstrate that AgNP induce ER stress and can target the UPR-dependent apoptotic pathway in MCF-7 and T-47D, which highlights new potential strategies for the treatment of breast cancers.

Growth inhibition and apoptosis in cancer cells induced by polyphenolic compounds of Acacia hydaspica: Involvement of multiple signal transduction pathways.

Acacia hydaspica R. Parker is known for its medicinal uses in multiple ailments. In this study, we performed bioassay-guided fractionation of cytotoxic compounds from A. hydaspica and investigated their effects on growth and signaling activity in prostate and breast cancer cell lines. Four active polyphenolic compounds were identified as 7-O-galloyl catechin (GC), catechin (C), methyl gallate (MG), and catechin-3-O-gallate (CG). The four compounds inhibited prostate cancer PC-3 cell growth in a dose-dependent manner, whereas CG and MG inhibited breast cancer MDA-MB-231 cell growth. All tested compounds inhibited cell survival and colony growth in both cell lines, and there was evidence of chromatin condensation, cell shrinkage and apoptotic bodies. Further, acridine orange, ethidium bromide, propidium iodide and DAPI staining demonstrated that cell death occurred partly via apoptosis in both PC-3 and MDA-MB-231 cells. In PC-3 cells treatment repressed the expression of anti-apoptotic molecules Bcl-2, Bcl-xL and survivin, coupled with down-regulation of signaling pathways AKT, NFκB, ERK1/2 and JAK/STAT. In MDA-MB-231 cells, treatment induced reduction of CK2α, Bcl-xL, survivin and xIAP protein expression along with suppression of NFκB, JAK/STAT and PI3K pathways. Our findings suggest that certain polyphenolic compounds derived from A. hydaspica may be promising chemopreventive/therapeutic candidates against cancer.

Tumor Microenvironment Regulates Survival of Mantle Cell Lymphoma Cells through Various Signaling Pathways

IntroductionAn aggressive, incurable form of non-Hodgkin's lymphoma (NHL) is classifed as Mantle cell lymphoma (MCL). The health complications associated with advanced age of restrict treatment with intense chemotherapy. Overexpression of cyclin-D1 due to Translocation t(11;14) , is the hallmark of MCL. More detailed insight into MCL pathogenesis has been delayed until the recent development of a tissue culture system, using human mesenchymal stromal cells (hMSC), suitable for propagating primary MCL cells. We hypothesized that tumor-initiating cells are responsible for MCL relapse and chemoresistance and thus, identification of signals responsible for survival and maintenance of MCL-initiating cells (MCL-ICs) is essential for design of curative treatment strategies.MethodsIsolates of primary MCL cells (n=24) were co-cultured with human mesenchymal stem cells (hMSCs) and the content of MCL-ICs was analyzed by flow-cytometry based on marker expression profile; CD34-CD3-CD45+CD19-. Cytokine array was used to identify the soluble factors enriched in the co-cultures and the expression of these factors was confirmed by RT-PCR analysis. The signaling pathways employed by the newly-identified factors were blocked in 3 MCL cell lines (JVM2, Mino, Z138) to confirm their essential role in survival of MCL cells and, more importantly, for MCL-ICs.ResultsCo-cultures of primary MCL isolates with hMSCs supported the growth of MCL cells for over 4 weeks with continued presence of MCL-ICs (CD34-CD3-CD45+CD19-) representing about 1% of MCL cells. We found that IL-6 produced by hMSCs triggered an FGF/FGFR autocrine loop in MCL-ICs. The extent of FGFR expression correlated tightly with expression of SOX11, a pathology related negative prognostic marker in MCL. MCL cell survival and growth was regulated via the FGFR/mir101/ EZH2/ NF-κB/XIAP axis. Blocking of this signaling pathway with FGFR1 inhibitors consistently induced early reduction in XIAP levels and subsequently MCL cell death.ConclusionWe established that propagation of primary MCL in co-cultures with hMSCs depends on an FGF/FGFR autocrine loop that enhances XIAP protein expression and thus, supports survival of MCL cells. We identified the factors essential for survival of MCL and MCL-ICs that present new targets for improved MCL treatment strategies. DisclosuresRodriguez:Orthobiotech: Research Funding.

Abstract 445: Tumor microenvironment influences survival of mantle cell lymphoma-initiating cells through FGF/FGFR1 signaling

Abstract Introduction Mantle cell lymphoma (MCL) represents an aggressive, incurable form of non-Hodgkin's lymphoma (NHL). The health complications associated with advanced age of MCL patients restrict treatment with intense chemotherapy. Translocation t(11;14), responsible for overexpression of cyclin-D1, is the hallmark of MCL. More detailed insight into MCL pathogenesis has been delayed until the recent development of a tissue culture system, using human mesenchymal stromal cells (hMSC), suitable for propagating primary MCL cells. We hypothesized that tumor-initiating cells are responsible for MCL relapse and chemoresistance and thus, identification of signals responsible for survival and maintenance of MCL-initiating cells (MCL-ICs) is essential for design of curative treatment strategies. Methods Isolates of primary MCL cells (n = 24) were co-cultured with human mesenchymal stem cells (hMSCs) and the content of MCL-ICs was analyzed by flow-cytometry based on marker expression profile; CD34-CD3-CD45+CD19-. Cytokine array was used to identify the soluble factors enriched in the co-cultures and the expression of these factors was confirmed by RT-PCR analysis. The signaling pathways employed by the newly-identified factors were blocked in 3 MCL cell lines (JVM2, Mino, Z138) to confirm their essential role in survival of MCL cells and, more importantly, for MCL-ICs. Results Co-cultures of primary MCL isolates with hMSCs supported the growth of MCL cells for over 4 weeks with continued presence of MCL-ICs (CD34-CD3-CD45+CD19-) representing about 1% of MCL cells. We found that IL-6 produced by hMSCs triggered an FGF/FGFR autocrine loop in MCL-ICs. The extent of FGFR expression correlated tightly with expression of SOX11, a pathology related negative prognostic marker in MCL. MCL cell survival and growth was regulated via the FGFR/mir101/ EZH2/ NF-κB/XIAP axis. Blocking of this signaling pathway with FGFR1 inhibitors consistently induced early reduction in XIAP levels and subsequently MCL cell death. Conclusion We established that propagation of primary MCL in co-cultures with hMSCs depends on an FGF/FGFR autocrine loop that enhances XIAP protein expression and thus, supports survival of MCL cells. We identified the factors essential for survival of MCL and MCL-ICs that present new targets for improved MCL treatment strategies. Citation Format: Lalit Sehgal, Rohit Mathur, Zuzana Berkova, Tamer Khashab, Xin Wang, Jorge E. Romaguera, Alma E. Rodriguez, Sattva Neelapu, Felipe Samaniego. Tumor microenvironment influences survival of mantle cell lymphoma-initiating cells through FGF/FGFR1 signaling. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 445. doi:10.1158/1538-7445.AM2015-445