XIAP expression is associated with pancreatic carcinoma outcome

A highly fluorescent and readily accessible all-organic photosensitizer model for advancing image-guided cancer PDT

The potential of using image-guided photodynamic therapy (ig-PDT) for cancer, especially with highly biocompatible fluorescent agents free of heavy atoms, is well recognized. This is due to key advantages related to minimizing adverse side effects associated with standard cancer chemotherapy. However, this theragnostic approach is strongly limited by the lack of synthetically-accessible and easily-modulable chemical scaffolds, enabling the rapid design and construction of advanced agents for clinical ig-PDT. In fact, there are still very few ig-PDT agents clinically approved. Herein we report a readily accessible, easy-tunable and highly fluorescent all-organic small photosensitizer, as a model design for accelerating the development and translation of advanced ig-PDT agents for cancer. This scaffold is based on BODIPY, which assures high fluorescence, accessibility, and ease of performance adaptation by workable chemistry. The optimal PDT performance of this BODIPY dye, tested in highly resistant pancreatic cancer cells, despite its high fluorescent behavior, maintained even after fixation and cancer cell death, is based on its selective accumulation in mitochondria. This induces apoptosis upon illumination, as evidenced by proteomic studies and flow cytometry. All these characteristics make the reported BODIPY-based fluorescent photosensitizer a valuable model for the rapid development of ig-PDT agents for clinical use.

BRCA mutations lead to XIAP overexpression and sensitise ovarian cancer to inhibitor of apoptosis (IAP) family inhibitors

Background

We tested the hypothesis that inhibitor of apoptosis family (IAP) proteins may be altered in BRCA1-mutated ovarian cancers and that could affect the sensitivity to IAP inhibitors.

Methods

The levels of IAP proteins were evaluated in human cancers and cell lines. Cell lines were used to determine the effects of IAP inhibitors. The in vivo effects of treatments were evaluated in PDX mouse models.

Results

Expression of X-linked inhibitor of apoptosis (XIAP) is increased in BRCA1-mutated cancers and high levels are associated with improved patient outcomes after platinum chemotherapy. XIAP overexpression is mediated by NF-kB activation and is associated with an optimisation of PARP. BRCA1-mutated cell lines are particularly sensitive to IAP inhibitors due to an inhibitory effect on PARP. Both a BRCA1-mutated cell line with acquired resistance to PARP inhibitors and one with restored BRCA1 remain sensitive to IAP inhibitors. Treatment with IAP inhibitors restores the efficacy of PARP inhibition in these cell lines. The IAP inhibitor LCL161 alone and in combination with a PARP inhibitor, exhibited antitumour effects in PDX mouse models of resistant BRCA2 and 1-mutated ovarian cancer, respectively.

Conclusion

A clinical trial may be justified to further investigate the utility of IAP inhibitors.

Targeting E2 ubiquitin-conjugating enzyme UbcH5c by small molecule inhibitor suppresses pancreatic cancer growth and metastasis

BACKGROUND

Pancreatic cancer is one of the most lethal cancers worldwide. The IAPs function as E3 ubiquitin ligases and contribute to pancreatic cancer initiation, progression, and metastasis. Although IAP-targeted therapies have been developed and shown anticancer efficacy in preclinical settings, none of them has been approved yet.

METHODS

Transcriptome data from public datasets were used to analyze the correlation of IAPs and E2s, and the biological function of E2 UbcH5c in pancreatic cancer. A structure-based virtual screen was used to identify UbcH5c inhibitor, and surface plasmon resonance analysis and cellular thermal shift assays were employed to evaluate the binding affinity. The anticancer activities were demonstrated through in vitro and in vivo assays, while the related mechanisms were explored through transcriptomic and proteomic analyses and confirmed by western blot, immunofluorescence, and qRT-PCR.

RESULTS

UbcH5c is positively correlated with the expression of IAPs in pancreatic cancer. We further found that UbcH5c is overexpressed and associated with a poor prognosis in pancreatic cancer. We identified a small-molecule UbcH5c inhibitor, termed DHPO, which directly bound to UbcH5c protein. DHPO inhibited cell viability and colony formation, induced apoptosis, and suppressed migration and invasion of pancreatic cancer cells in vitro. The compound inhibited UbcH5c-mediated IκBα degradation and NF-κB activation, which is critical for its anticancer activity. Furthermore, DHPO suppressed the tumor growth and metastasis in two orthotopic pancreatic tumor mouse models.

CONCLUSIONS

These results indicated that inhibiting UbcH5c is a novel and effective strategy for treating pancreatic cancer and DHPO represents a new class of UbcH5c inhibitor and may be further developed as an anti-pancreatic cancer therapeutic agent.

Subcellular localization of X-linked inhibitor of apoptosis protein (XIAP) in cancer: does that matter?

X-linked inhibitor of apoptosis protein (XIAP) finely tunes the balance between survival and death to control homeostasis. XIAP is found aberrantly expressed in cancer, which has been shown to promote resistance to therapy-induced apoptosis and confer poor outcome. Despite its predominant cytoplasmic localization in human tissues, growing evidence implicates the expression of XIAP in other subcellular compartments in sustaining cancer hallmarks. Herein, we review our current knowledge on the prognostic role of XIAP localization and discuss molecular mechanisms underlying differential biological functions played in each compartment. The comprehension of XIAP subcellular shuttling and functional dynamics might provide the rationale for future anticancer therapeutics.

Emerging neo adjuvants for harnessing therapeutic potential of M1 tumor associated macrophages (TAM) against solid tumors: Enusage of plasticity

Macrophages are a major component of the tumor microenvironment (TME) of most tumors. They are characterized by a high degree of functional plasticity which enable these cells to both promote and eliminate established tumors. Under the influence of immunosuppressive TME, tumor infiltrating iNOS+ and CD11b+ M-1 effector macrophages get polarized towards tumor associated macrophages (TAM) which are tropic to variety of tumors. Increased infiltration and density of TAM is associated with tumor progression and poor prognosis in the plethora of tumors due to their angiogenetic and tissue re-modelling nature. Importantly, TAMs are also responsible for developing endothelium anergy, a major physical barrier for majority of cancer directed immune/chemotherapies. Therefore, functional retuning/re-educating TAM to M-1 phenotypic macrophages is paramount for effective immunotherapy against established tumors. In this review, we discuss and provide comprehensive update on TAM-targeted approaches for enhancing immunity against various solid tumors.

Prognostic significance of X-linked inhibitor of apoptosis protein in solid tumors: A systematic review and meta-analysis

X-linked inhibitor of apoptosis protein (XIAP) is aberrantly expressed in solid tumors. Considering conflicting data, we conducted this meta-analysis to investigate its prognostic role. Electronic databases were searched to collect studies about associations between XIAP expressions and survival outcomes. Hazard ratio (HR), odds ratio (OR), and 95% confidence interval (CI) were utilized as effect size estimates. A total of 3,794 patients from 21 published studies were included. The results revealed that high XIAP expressions correlated with age (OR = 2.02; 95% CI, 1.07-3.84), lymph node metastasis (OR = 1.69; 95% CI, 1.02-2.77), histological grade (OR = 2.04; 95% CI, 1.01-4.11), and tumor stage (OR = 2.18; 95% CI, 1.20-3.96). The combined HR revealed that high XIAP expressions associated with poor overall survival (OS) (HR = 1.60; 95% CI, 1.22-2.10). Our study suggested high XIAP expressions may be indicative of poor prognosis in solid tumors.

Prognostic Value of XIAP Level in Patients with Various Cancers: A Systematic Review and Meta-Analysis

Background: X-linked inhibitor of apoptosis protein (XIAP) plays an important role in cancer pathogenesis, which has been found to be overexpressed in multiple human cancers and associated with survival rates. Herein, we performed a meta-analysis to explore the predictive value of XIAP level in patients with various solid tumors. Methods: Relevant articles exploring the relationship between XIAP expression and survival of cancer patients were retrieved in PubMed, PMC, EMBASE and Web of Science published from 2001 to 2018. The combined hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated to evaluate the significance. Results: A total of 6554 patients from 40 articles were included in this meta-analysis. It was shown in 37 studies with 4864 cases that the over-expression of XIAP was associated with poorer overall survival (OS) (combined HR=1.61, 95% CI: 1.33-1.96). Meanwhile, 8 studies with 1862 cases revealed that elevated XIAP level predicted shorter disease-free survival (DFS) (HR=2.17, 95% CI: 1.03-4.59). Subgroup analyses showed that higher XIAP detection was related to worse OS in gastric cancer (HR=1.42, 95% CI: 1.18-1.72) and head and neck cancer (HNC) (HR=2.97, 95% CI: 1.97-4.47). Conclusion: Our results suggested that elevated XIAP level seemed to represent an unfavorable prognostic factor for clinical outcomes in cancer patients. However, there were limited studies describing the association between XIAP expression and clinical prognosis in each different type of tumors. Therefore, concrete roles of XIAP in various cancers need to be further explored.

KRas4B-PDE6δ complex stabilization by small molecules obtained by virtual screening affects Ras signaling in pancreatic cancer

Background

The GTPase KRas4B has been utilized as a principal target in the development of anticancer drugs. PDE6δ transports KRas4B to the plasma membrane, where it is released to activate various signaling pathways required for the initiation and maintenance of cancer. Therefore, identifying new small molecules that prevent activation of this GTPase by stabilizing the KRas4B-PDE6δ molecular complex is a practical strategy to fight against cancer.

Methods

The crystal structure of the KRas4B-PDE6δ heterodimer was employed to locate possible specific binding sites at the protein-protein interface region. Virtual screening of Enamine-database compounds was performed on the located potential binding sites to identify ligands able to simultaneously bind to the KRas4B-PDE6δ heterodimer. A molecular dynamics approach was used to estimate the binding free-energy of the complex. Cell viability and apoptosis were measured by flow cytometry. G-LISA was used to measure Ras inactivation. Western blot was used to measure AKT and ERK activation. MIA PaCa-2 cells implanted subcutaneously into nude mice were treated with D14 or C22 and tumor volumes were recorded.

Results

According to the binding affinity estimation, D14 and C22 stabilized the protein-protein interaction in the KRas4B-PDE6δ complex based on in vitro evaluation of the 38 compounds showing antineoplastic activity against pancreatic MIA PaCa-2 cancer cells. In this work, we further investigated the antineoplastic cellular properties of two of them, termed D14 and C22, which reduced the viability in the human pancreatic cancer cells lines MIA PaCa-2, PanC-1 and BxPC-3, but not in the normal pancreatic cell line hTERT-HPNE. Compounds D14 and C22 induced cellular death via apoptosis. D14 and C22 significantly decreased Ras-GTP activity by 33% in MIA PaCa-2 cells. Moreover, D14 decreased AKT phosphorylation by 70% and ERK phosphorylation by 51%, while compound C22 reduced AKT phosphorylation by 60% and ERK phosphorylation by 36%. In addition, compounds C22 and D14 significantly reduced tumor growth by 88.6 and 65.9%, respectively, in a mouse xenograft model.

Conclusions

We identified two promising compounds, D14 and C22, that might be useful as therapeutic drugs for pancreatic ductal adenocarcinoma treatment.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-5142-7) contains supplementary material, which is available to authorized users.

MicroRNA-509-3p inhibits cell proliferation and invasion via downregulation of X-linked inhibitor of apoptosis in glioma

Malignant glioma is an aggressive type of cancer. Increasing evidence has suggested that microRNAs (miRs) regulate gene expression post-transcriptionally to affect cancer development and progression. Aberrant expression of miR-509-3p has been reported in cancer studies. However, the expression and mechanism of its function in glioma remains unclear. The present study demonstrated that miR-509-3p was downregulated in glioma tissue samples relative to non-tumor tissues, and that low miR-509-3p expression was associated with a reduced overall survival time. Functional studies revealed that the overexpression of miR-509-3p inhibited cell proliferation, induced apoptosis and suppressed cell migration and invasion via negatively regulating the expression of X-linked inhibitor of apoptosis. The data therefore suggested that miR-509-3p serves an important role in the development and progression of glioma, implicating its possible application in clinical practice as a biomarker and a potential novel therapeutic target.

Upregulation of miR‑185 promotes apoptosis of the human gastric cancer cell line MGC803

MicroRNA (miR)-185, which has been reported to be abnormally expressed in some types of cancer, exerts significant effects on the proliferation, apoptosis, drug resistance and metastasis of cancer cells. The present study aimed to explore the effects and underlying molecular mechanisms of miR‑185 upregulation on the apoptosis of gastric cancer (GC) cells. Quantitative polymerase chain reaction (qPCR) and western blotting were used to detect the expression levels of miR‑185 in GC and adjacent normal tissues. In addition, miR‑185 expression was detected in the following GC cell lines: MKN74, SGC7901, BGC823, MGC803, as well as in the gastric epithelial cell line GES‑1. Subsequently, miR‑185 mimics were transfected into MGC803 cells. Post‑transfection, the following experiments were conducted: MTT assay was applied to test cell viability; flow cytometry (FCM) was used to determine the apoptotic rate of the cells; and qPCR and western blotting were conducted to detect the expression levels of the following apoptosis‑associated factors: B‑cell lymphoma 2 (Bcl‑2), Bcl‑2‑associated X protein (Bax), survivin, X‑linked inhibitor of apoptosis protein (XIAP), livin, caspase‑3 and caspase‑8. The results demonstrated that miR‑185 was downregulated in GC tissues compared with the adjacent tissues. In cell lines, miR‑185 expression was higher in GES‑1 cells compared with in the GC cell lines; in the 4 GC cell lines, the strongest miR‑185 expression was in MKN74 cells, followed by SGC7901 and BGC823 cells, and the weakest was in MGC803 cells (P<0.05). Expression of miR‑185 was associated with tumor size, differentiation and lymphatic metastasis. Post-transfection with miR‑185 mimics, miR‑185 expression was significantly increased in a time‑ and concentration‑dependent manner. MGC803 cell viability was significantly decreased following miR‑185 mimics transfection. The results of FCM demonstrated that post‑transfection with miR‑185 mimics, the apoptotic rate of MGC803 cells was significantly increased. Post‑transfection with miR‑185 mimics, the expression levels of Bcl‑2, survivin and XIAP were significantly decreased in MGC803 cells, whereas the expression levels of Bax and livin were not altered, and caspase‑3 and caspase‑8 expression was significantly increased. Spectrophotometry indicated that caspase‑3 and caspase‑8 activity was significantly increased in MGC803 cells following transfection with miR‑185 mimics. In conclusion, the present study suggested that miR‑185 upregulation in GC cells may promote apoptosis of tumor cells via gene expression regulation.

Mir-23a inhibition attenuates ischemic/reperfusion-induced myocardial apoptosis by targeting XIAP

MicroRNAs are a group of single-strand, non-coding RNAs that inhibit the translation of protein-coding genes. Recent studies indicated that miRNAs are broadly involved in the development of cardiovascular diseases, including arrhythmia, hypertrophy, heart failure and cardiac injury. In this study, we report that miR-23a, a tumor suppressor, acts as an apoptotic promoter in rats undergoing ischemic/reperfusion. In rats subjected to ischemic/reperfusion injury, the expression of miR-23a in heart tissue was upregulated significantly. The infarct area and the apoptosis rate also increased. In contrast, knockdown of miR-23a by tail injection of antagomir-23a attenuated the ischemic/reperfusion injury. Moreover, we used Western blots to determine that miR-23a targeted XIAP to influence the expression of caspase and the NFkB pathway. In summary, miR-23a was shown to be part of a novel regulatory pathway that contributed to ischemic/reperfusion injury.

Imatinib induces autophagy via upregulating XIAP in GIST882 cells

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms originating from the gastrointestinal tract with gain of function mutations in receptor tyrosine kinases KIT or platelet-derived growth factor receptor A (PDGFRA). The main effective treatment for GISTs is tyrosine kinase inhibitors, such as imatinib mesylate. However, GISTs respond to imatinib treatment eventually develop acquired resistance, which is a main obstacle for GISTs therapy. Therefore, it's urgent to have a better understanding of the mechanisms underlying the imatinib resistance in GISTs to develop novel therapeutic strategies. X-linked inhibitor of apoptosis (XIAP) is the most potent apoptosis inhibitor among the inhibitor of apoptosis protein (IAP) family members. Increased cellular expression of XIAP often leads to drug resistance in cancers. Here we report that XIAP is induced upon imatinb treatment in GIST882 cells, leading to imatinib-induced autophagy. Imatinib-induced autophagy was impaired in XIAP-knockout cells generated by CRISPR/Cas9 system demonstrated by the decreasing of LC3 lipidation. XIAP knockout sensitizes GIST882 cells to imatinib-induced apoptotic cell death, suggesting that XIAP protects GIST882 cells from imatinib-induced cell death by inducing autophagy. Thus, the resistance of the GIST882 cells to imatinib appears to be, in part, due to the increasing of XIAP and subsequent induction of autophagy.

XIAP inhibits mature Smac-induced apoptosis by degrading it through ubiquitination in NSCLC

X-linked inhibitor of apoptosis protein (XIAP) and second mitochondrial-derived activator of caspase (Smac) are two important prognostic biomarkers for cancer. They are negatively correlated in many types of cancer. However, their relationship is still unknown in lung cancer. In the present study, we found that there was a negative correlation between Smac and XIAP at the level of protein but not mRNA in NSCLC patients. However, XIAP overexpression had no effect on degrading endogenous Smac in lung cancer cell lines. Therefore, we constructed plasmids with full length of Smac (fSmac) and mature Smac (mSmac) which located in cytoplasm instead of original mitochondrial location, and was confirmed by immunofluorescence. Subsequently, we found that mSmac rather than fSmac was degraded by XIAP and inhibited cell viability. CHX chase assay and ubiquitin assay were performed to illustrate XIAP degraded mSmac through ubiquitin pathway. Overexpression of XIAP partially reverted apoptotic induction and cell viability inhibition by mSmac, which was due to inhibiting caspase-3 activation. In nude mouse xenograft experiments, mSmac inhibited Ki-67 expression and slowed down lung cancer growth, while XIAP partially reversed the effect of mSmac by degrading it. In conclusion, XIAP inhibits mature Smac-induced apoptosis by degrading it through ubiquitination in NSCLC.

Paeoniflorin inhibits human pancreatic cancer cell apoptosis via suppression of MMP-9 and ERK signaling

Paeoniflorin exhibits anticancer, anti-inflammatory and antioxidation effects, as well as specific pharmacological effects on smooth muscle and the immune, cardiovascular and central nervous systems. The present study aimed to investigate the anticancer effects of paeoniflorin on pancreatic cancer cells and to elucidate the mechanisms by which these effects occur. In the present study, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and lactate dehydrogenase assays were performed to assess cell viability and cell cytotoxicity of BXPC-3 human pancreatic cancer cells, respectively. Cellular apoptosis and caspase-3/9 activities were analyzed using an Annexin V-fluorescein isothiocyanate/propidium iodide Apoptosis Detection kit, a DAPI staining assay and colorimetric kits, respectively. Matrix metalloproteinase-9 (MMP-9) and extracellular signal-regulated kinases (ERK) protein expression in BXPC-3 cells were also investigated using gelatin zymography assays and western blot analysis, respectively. In the present study, paeoniflorin was found to inhibit the cell viability and increase cell cytotoxicity of BXPC-3 cells in a dose- and time-dependent manner. In addition, cellular apoptosis, as well as caspase-3 and -9 activity of BXPC-3 cells was increased following paeoniflorin treatment. Notably, paeoniflorin reduced MMP-9 and ERK protein expression in BXPC-3 cells. These results indicate that paeoniflorin exhibits a potential anticancer effect by enhancing human pancreatic cancer cell apoptosis via the suppression of MMP-9 and ERK signaling.

ApoCanD: Database of human apoptotic proteins in the context of cancer

In the past decade, apoptosis pathway has gained a serious consideration being a critical cellular process in determining the cancer progression. Inverse relationship between cancer progression and apoptosis rate has been well established in the literature. It causes apoptosis proteins under the investigative scanner for developing anticancer therapies, which certainly got a success in the case of few apoptosis proteins as drug targets. In the present study, we have developed a dedicated database of 82 apoptosis proteins called ApoCanD. This database comprises of crucial information of apoptosis proteins in the context of cancer. Genomic status of proteins in the form of mutation, copy number variation and expression in thousands of tumour samples and cancer cell lines are the major bricks of this database. In analysis, we have found that TP53 and MYD88 are the two most frequently mutated proteins in cancer. Availability of other information e.g. gene essentiality data, tertiary structure, sequence alignments, sequences profiles, post-translational modifications makes it even more useful for the researchers. A user-friendly web interface is provided to ameliorate the use of ApoCanD. We anticipate that, this database will facilitate the research community working in the field of apoptosis and cancer. The database can be accessed at: http://crdd.osdd.net/raghava/apocand.