An 8-aminoquinoline-naphthyl copper complex causes apoptotic cell death by modulating the expression of apoptotic regulatory proteins in breast cancer cells.

Breast cancer is one of the most common cancers globally and a leading cause of cancer-related deaths among women. Despite the combination of chemotherapy with targeted therapy, including monoclonal antibodies and kinase inhibitors, drug resistance and treatment failure remain a common occurrence. Copper, complexed to various organic ligands, has gained attention as potential chemotherapeutic agents due to its perceived decreased toxicity to normal cells. The cytotoxic efficacy and the mechanism of cell death of an 8-aminoquinoline-naphthyl copper complex (Cu8AqN) in MCF-7 and MDA-MB-231 breast cancer cell lines was investigated. The complex inhibited the growth of MCF-7 and MDA-MB-231 cells with IC50 values of 2.54 ± 0.69 µM and 3.31 ± 0.06 µM, respectively. Nuclear fragmentation, annexin V binding, and increased caspase-3/7 activity indicated apoptotic cell death. The loss of mitochondrial membrane potential, an increase in caspase-9 activity, the absence of active caspase-8 and a decrease of tumour necrosis factor receptor 1(TNFR1) expression supported activation of the intrinsic apoptotic pathway. Increased ROS formation and increased expression of haem oxygenase-1 (HMOX-1) indicated activation of cellular stress pathways. Expression of p21 protein in the nuclei was increased indicating cell cycle arrest, whilst the expression of inhibitor of apoptosis proteins (IAPs); cIAP1, XIAP and survivin were decreased, creating a pro-apoptotic environment. Phosphorylated p53 species; phospho-p53(S15), phospho-p53(S46), and phospho-p53(S392) accumulated in MCF-7 cells indicating the potential of Cu8AqN to restore p53 function in the cells. In combination, the data indicates that Cu8AqN is a useful lead molecule worthy of further exploration as a potential anti-cancer drug.

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.

IAPs and RIPK1 mediate LPS-induced cytokine production in healthy subjects and Crohn's disease.

Innate immune activity fuels intestinal inflammation in Crohn's disease (CD), an inflammatory bowel disease. Identification and targeting of new molecular regulators of the innate activity are warranted to control the disease. Inhibitor of apoptosis proteins (IAPs) regulate both cell survival and inflammatory signaling. We investigated the effects of IAP inhibition by second mitochondria-derived activator of caspases (SMAC) mimetics (SMs) on innate responses and cell death to pathogen-associated molecular patterns in peripheral blood mononuclear cells (PBMCs) and monocytes. IAPs inhibited lipopolysaccharide (LPS)-induced expression of proinflammatory interleukin (IL)-1ß, IL-6. Likewise, LPS (but not muramyl dipeptide or Escherichia coli) induced TNF-α was inhibited in CD and control PBMCs. The SM effect was partially reversed by inhibition of receptor-interacting serine/threonine-protein kinase 1 (RIPK1). The effect was mainly cell death independent. Thus, IAP inhibition by SMs leads to reduced production of proinflammatory cytokines and may be considered in the efforts to develop new therapeutic strategies to control CD.

Birinapant selectively enhances immunotoxin-mediated killing of cancer cells conditional on the IAP protein levels within target cells.

Immunotoxins (ITs) target cancer cells via antibody binding to surface antigens followed by internalization and toxin-mediated inhibition of protein synthesis. The fate of cells responding to IT treatment depends on the amount and stability of specific pro-apoptotic and pro-survival proteins. When treated with a pseudomonas exotoxin-based immunotoxin (HB21PE40), the triple-negative breast cancer (TNBC) cell line MDA-MB-468 displayed a notable resistance to toxin-mediated killing compared to the epidermoid carcinoma cell line, A431, despite succumbing to the same level of protein synthesis inhibition. In a combination screen of ~1912 clinically relevant and mechanistically annotated compounds, we identified several agents that greatly enhanced IT-mediated killing of MDA-MB-468 cells while exhibiting only a modest enhancement for A431 cells. Of interest, two Smac mimetics, birinapant and SM164, exhibited this kind of differential enhancement. To investigate the basis for this, we probed cells for the presence of inhibitor of apoptosis (IAP) proteins and monitored their stability after the addition of immunotoxin. We found that high levels of IAPs inhibited immunotoxin-mediated cell death. Further, TNFα levels were not relevant for the combination's efficacy. In tumor xenograft studies, combinations of immunotoxin and birinapant caused complete regressions in MDA-MB-468tumor-bearing mice but not in mice with A431 tumors. We propose that IAPs constitute a barrier to immunotoxin efficacy which can be overcome with combination treatments that include Smac mimetics.

DNMT3A governs tyrosine kinase inhibitors responses through IAPs and in a cell senescence-dependent manner in non-small cell lung cancer.

Patients with non-small cell lung cancer (NSCLC) treated with tyrosine kinase inhibitors (TKIs) inevitably exhibit drug resistance, which diminishes therapeutic effects. Nonetheless, the molecular mechanisms of TKI resistance in NSCLC remain obscure. In this study, data from clinical and TCGA databases revealed an increase in DNMT3A expression, which was correlated with a poor prognosis. Using NSCLC organoid models, we observed that high DNMT3A levels reduced TKI susceptibility of NSCLC cells via upregulating inhibitor of apoptosis proteins (IAPs). Simultaneously, the DNMT3Ahigh subset, which escaped apoptosis, underwent an early senescent-like state in a CDKN1A-dependent manner. Furthermore, the cellular senescence induced by TKIs was observed to be reversible, whereas DNMT3Ahigh cells reacquired their proliferative characteristics in the absence of TKIs, resulting in subsequent tumour recurrence and growth. Notably, the blockade of DNMT3A/IAPs signals enhanced the efficacy of TKIs in DNMT3Ahigh tumour-bearing mice, which represented a promising strategy for the effective treatment of NSCLC.

Inhibitor of apoptosis proteins as therapeutic targets in bladder cancer.

Evasion from apoptosis is a hallmark of cancer. Inhibitor of apoptosis proteins (IAPs) contribute to this hallmark by suppressing the induction of cell death. IAPs were found to be overexpressed in cancerous tissues and to contribute to therapeutic resistance. The present review focuses on the IAP members cIAP1, cIAP2, XIAP, Survivin and Livin and their importance as potential therapeutic targets in bladder cancer.

BV6 enhances apoptosis in Lung cancer cells by ameliorating caspase expressions through attenuation of XIAP, cIAP-1, and cIAP-2 proteins.

Objective: The present study aimed to investigate the inhibitory role of second mitochondria determined activator of caspases mimetic on inhibitor of apoptosis proteins (IAPs) and regulation of caspases in nonsmall cell lung cancer cell line. Materials and Methods: Dimethyl sulfoxide and 3-(4, 5-dimethyl thizol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay was done to determine the IC50 of BV6 using NCI-H23 cell line. The levels of mRNA of X-linked IAP (XIAP), cellular IAP (cIAP-1), cIAP-2, caspase-6, and caspase-7 in H23 cell line were evaluated by a quantitative real-time polymerase chain reaction, while their protein expressions were tested using western blotting. Results: Two doses of BV6 dependently downregulated the expression of mRNA of XIAP (P = 0.002, P= 0.0003 vs. untreated), cIAP-1 (P = 0.05, P = 0.005 vs. untreated), and cIAP-2 (P = 0.001, P = 0.0002 vs. untreated), respectively, while the compound upregulated the mRNA expression of caspase-6 (P = 0.001, P < 0.0001 vs. untreated) and caspase-7 (P = 0.001, P = 0.0004 vs. untreated), respectively. Dose dependent of BV6 treatment significantly decreased the protein level of XIAP (P = 0.003, P = 0.007 vs. untreated), cIAP-1 (P = 0.02, P = 0.01 vs. untreated), and cIAP-2 (P = 0.008,P = 0.008 vs. untreated), respectively. However, the compound increased the protein level of caspase-6 and caspase-7 when compared to untreated control (P = 0.006,P = 0.001) and (P = 0.01, P = 0.001), respectively. Conclusions: The result showed that BV6 treatment reduced the level of mRNA of XIAP, cIAP-1, and cIAP-2 and increased the gene expression of caspase-6 and caspase-7 in NCI-H23 cell line. Therefore, the study revealed that BV6 could be used in future as additional therapeutics in lung cancer.

Proteasomal Degradation of TRAF2 Mediates Mitochondrial Dysfunction in Doxorubicin-Cardiomyopathy.

BACKGROUND: Cytokines such as tumor necrosis factor-α (TNFα) have been implicated in cardiac dysfunction and toxicity associated with doxorubicin (DOX). Although TNFα can elicit different cellular responses, including survival or death, the mechanisms underlying these divergent outcomes in the heart remain cryptic. The E3 ubiquitin ligase TRAF2 (TNF receptor associated factor 2) provides a critical signaling platform for K63-linked polyubiquitination of RIPK1 (receptor interacting protein 1), crucial for nuclear factor-κB (NF-κB) activation by TNFα and survival. Here, we investigate alterations in TNFα-TRAF2-NF-κB signaling in the pathogenesis of DOX cardiotoxicity. METHODS: Using a combination of in vivo (4 weekly injections of DOX 5 mg·kg-1·wk-1) in C57/BL6J mice and in vitro approaches (rat, mouse, and human inducible pluripotent stem cell-derived cardiac myocytes), we monitored TNFα levels, lactate dehydrogenase, cardiac ultrastructure and function, mitochondrial bioenergetics, and cardiac cell viability. RESULTS: In contrast to vehicle-treated mice, ultrastructural defects, including cytoplasmic swelling, mitochondrial perturbations, and elevated TNFα levels, were observed in the hearts of mice treated with DOX. While investigating the involvement of TNFα in DOX cardiotoxicity, we discovered that NF-κB was readily activated by TNFα. However, TNFα-mediated NF-κB activation was impaired in cardiac myocytes treated with DOX. This coincided with loss of K63- linked polyubiquitination of RIPK1 from the proteasomal degradation of TRAF2. Furthermore, TRAF2 protein abundance was markedly reduced in hearts of patients with cancer treated with DOX. We further established that the reciprocal actions of the ubiquitinating and deubiquitinating enzymes cellular inhibitors of apoptosis 1 and USP19 (ubiquitin-specific peptidase 19), respectively, regulated the proteasomal degradation of TRAF2 in DOX-treated cardiac myocytes. An E3-ligase mutant of cellular inhibitors of apoptosis 1 (H588A) or gain of function of USP19 prevented proteasomal degradation of TRAF2 and DOX-induced cell death. Furthermore, wild-type TRAF2, but not a RING finger mutant defective for K63-linked polyubiquitination of RIPK1, restored NF-κB signaling and suppressed DOX-induced cardiac cell death. Last, cardiomyocyte-restricted expression of TRAF2 (cardiac troponin T-adeno-associated virus 9-TRAF2) in vivo protected against mitochondrial defects and cardiac dysfunction induced by DOX. CONCLUSIONS: Our findings reveal a novel signaling axis that functionally connects the cardiotoxic effects of DOX to proteasomal degradation of TRAF2. Disruption of the critical TRAF2 survival pathway by DOX sensitizes cardiac myocytes to TNFα-mediated necrotic cell death and DOX cardiotoxicity.

The conservation of IAP-like proteins in fungi, and their potential role in fungal programmed cell death.

Programmed cell death (PCD) is a tightly regulated process which is required for survival and proper development of all cellular life. Despite this ubiquity, the precise molecular underpinnings of PCD have been primarily characterized in animals. Attempts to expand our understanding of this process in fungi have proven difficult as core regulators of animal PCD are apparently absent in fungal genomes, with the notable exception of a class of proteins referred to as inhibitors of apoptosis proteins (IAPs). These proteins are characterized by the conservation of a distinct Baculovirus IAP Repeat (BIR) domain and animal IAPs are known to regulate a number of processes, including cellular death, development, organogenesis, immune system maturation, host-pathogen interactions and more. IAP homologs are broadly conserved throughout the fungal kingdom, but our understanding of both their mechanism and role in fungal development/virulence is still unclear. In this review, we provide a broad and comparative overview of IAP function across taxa, with a particular focus on fungal processes regulated by IAPs. Furthermore, their putative modes of action in the absence of canonical interactors will be discussed.

Targeting inhibitor of apoptosis proteins (IAPs) with IAP inhibitors sensitises malignant rhabdoid tumour cells to cisplatin.

Malignant rhabdoid tumour (MRT) is a rare, aggressive paediatric malignancy most commonly diagnosed in those below the age of three. MRTs can arise in soft tissue but are more often associated with the central nervous system or kidney. Unfortunately, the prognosis upon diagnosis with MRT is poor. Given the resistance of MRT to current treatment protocols including cisplatin, and the vulnerability of this young patient population to aggressive therapies, there is a need for novel treatment options. Several members of the inhibitor of apoptosis protein (IAP) family including X­linked inhibitor of apoptosis (XIAP), cellular inhibitor of apoptosis proteins 1 and 2 (cIAP1/cIAP2), livin and survivin have been implicated in chemotherapy resistance in various malignancies. We have previously demonstrated expression of these IAP family members in a panel of MRT cell lines. In the present study, sensitivity of this same panel of MRT cell lines to small-molecule mediated inhibition of the IAPs via the survivin inhibitor YM155 and the XIAP/cIAP1/cIAP2 inhibitor BV6 was demonstrated. Additionally, both BV6 and the XIAP inhibitor embelin synergistically enhanced cisplatin mediated apoptotic cell death in MRT cell lines, with enhanced caspase-3 cleavage. Importantly, we have demonstrated, for the first time, expression of XIAP, its target caspase-3 and its endogenous inhibitor SMAC in rhabdoid tumour patient tissue. In conclusion, this study provides pre-clinical evidence that IAP inhibition may be a new therapeutic option in MRT.

A Review of the Current Impact of Inhibitors of Apoptosis Proteins and Their Repression in Cancer.

The Inhibitor of Apoptosis (IAP) family possesses the ability to inhibit programmed cell death through different mechanisms; additionally, some of its members have emerged as important regulators of the immune response. Both direct and indirect activity on caspases or the modulation of survival pathways, such as nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), have been implicated in mediating its effects. As a result, abnormal expression of inhibitor apoptosis proteins (IAPs) can lead to dysregulated apoptosis promoting the development of different pathologies. In several cancer types IAPs are overexpressed, while their natural antagonist, the second mitochondrial-derived activator of caspases (Smac), appears to be downregulated, potentially contributing to the acquisition of resistance to traditional therapy. Recently developed Smac mimetics counteract IAP activity and show promise in the re-sensitization to apoptosis in cancer cells. Given the modest impact of Smac mimetics when used as a monotherapy, pairing of these compounds with other treatment modalities is increasingly being explored. Modulation of molecules such as tumor necrosis factor-α (TNF-α) present in the tumor microenvironment have been suggested to contribute to putative therapeutic efficacy of IAP inhibition, although published results do not show this consistently underlining the complex interaction between IAPs and cancer.

The expanded inhibitor of apoptosis gene family in oysters possesses novel domain architectures and may play diverse roles in apoptosis following immune challenge.

BACKGROUND: Apoptosis plays important roles in a variety of functions, including immunity and response to environmental stress. The Inhibitor of Apoptosis (IAP) gene family of apoptosis regulators is expanded in molluscs, including eastern, Crassostrea virginica, and Pacific, Crassostrea gigas, oysters. The functional importance of IAP expansion in apoptosis and immunity in oysters remains unknown. RESULTS: Phylogenetic analysis of IAP genes in 10 molluscs identified lineage specific gene expansion in bivalve species. Greater IAP gene family expansion was observed in C. virginica than C. gigas (69 vs. 40), resulting mainly from tandem duplications. Functional domain analysis of oyster IAP proteins revealed 3 novel Baculoviral IAP Repeat (BIR) domain types and 14 domain architecture types across gene clusters, 4 of which are not present in model organisms. Phylogenetic analysis of bivalve IAPs suggests a complex history of domain loss and gain. Most IAP genes in oysters (76% of C. virginica and 82% of C. gigas), representing all domain architecture types, were expressed in response to immune challenge (Ostreid Herpesvirus OsHV-1, bacterial probionts Phaeobacter inhibens and Bacillus pumilus, several Vibrio spp., pathogenic Aliiroseovarius crassostreae, and protozoan parasite Perkinsus marinus). Patterns of IAP and apoptosis-related differential gene expression differed between the two oyster species, where C. virginica, in general, differentially expressed a unique set of IAP genes in each challenge, while C. gigas differentially expressed an overlapping set of IAP genes across challenges. Apoptosis gene expression patterns clustered mainly by resistance/susceptibility of the oyster host to immune challenge. Weighted Gene Correlation Network Analysis (WGCNA) revealed unique combinations of transcripts for 1 to 12 IAP domain architecture types, including novel types, were significantly co-expressed in response to immune challenge with transcripts in apoptosis-related pathways. CONCLUSIONS: Unprecedented diversity characterized by novel BIR domains and protein domain architectures was observed in oyster IAPs. Complex patterns of gene expression of novel and conserved IAPs in response to a variety of ecologically-relevant immune challenges, combined with evidence of direct co-expression of IAP genes with apoptosis-related transcripts, suggests IAP expansion facilitates complex and nuanced regulation of apoptosis and other immune responses in oysters.

Xevinapant or placebo plus chemoradiotherapy in locally advanced squamous cell carcinoma of the head and neck: TrilynX phase III study design.

Xevinapant is a first-in-class antagonist of inhibitor of apoptosis proteins, which enhances cancer cell sensitivity to chemotherapy and radiotherapy. In a phase II randomized study in patients with unresected locally advanced squamous cell carcinoma of the head and neck (LA SCCHN), xevinapant plus standard-of-care cisplatin-based chemoradiotherapy (CRT) showed superior efficacy versus placebo plus CRT. Here, we describe the design of TrilynX (NCT04459715), a randomized, double-blind, phase III study. In total, 700 patients with unresected LA SCCHN will be randomized 1:1 to receive xevinapant or placebo plus standard-of-care CRT followed by xevinapant monotherapy or placebo. The primary end point is event-free survival by blinded independent review committee. Secondary end points include progression-free survival, locoregional control, overall survival and safety.

Xevinapant is being developed as a new type of cancer treatment. Xevinapant works by enhancing the effects of chemotherapy and radiotherapy (chemoradiotherapy), which are standard anticancer treatments. Researchers are studying whether adding xevinapant to these treatments could be helpful for people with head and neck cancers that have not spread to other parts of the body and cannot be removed by surgery. In a study of 96 people with this disease, those treated with chemoradiotherapy plus xevinapant on average lived longer than people treated with chemoradiotherapy plus placebo (liquid that looked the same but did not contain any medicine). To confirm the results, researchers have started a larger study, called TrilynX, that will compare the same treatments in around 700 people worldwide. This study will show if adding xevinapant to chemoradiotherapy can help to keep the cancer from progressing, control symptoms better and help people live longer. Clinical trial registration: NCT04459715 (ClinicalTrials.gov).

Immunohistochemical expression of survivin in oral epithelial dysplasia and different grades of oral squamous cell carcinoma.

Background: Survivin, a member of the inhibitor of apoptosis proteins family, is not detectable in most differentiated normal adult tissues but is expressed in a wide range of cancer tissues. Survivin expression in cancer has been associated with poor prognosis, cancer progression, and drug resistance, and the expression levels correlate with more aggressive disease and a poor clinical outcome. Objective: To evaluate and compare the immunoexpression of survivin in the normal oral epithelium (NOE), oral epithelial dysplasia (OED), and different grades of oral squamous cell carcinoma (OSCC). Methodology: The patterns of survivin immunoexpression and immunoreactivity were assessed in previously diagnosed, paraffin-embedded sections of 10 tissues of NOE and 15 tissues each of OED and the three grades of OSCC (well-, moderately-, and poorly-differentiated). The pattern of survivin expression was recorded as cytoplasmic, nuclear, or both. Survivin immunoreactivity was assessed semi-quantitatively as the immunoreactive score (IRS). Analysis of variance and Tukey-HSD tests were employed for statistical analysis. Results: No immunoreactivity for survivin was evident in the NOE tissues. In the OED tissues, the immunoexpression pattern of survivin was predominantly nuclear in the basal cells, and in the OSCC tissues, cytoplasmic and nuclear. IRS was highest among the moderately- differentiated OSCC, followed by poorly- and well-differentiated OSCC and OED, with a statistically significant difference in the IRS scores between the normal and the study groups. Conclusion: Survivin protein expression may be an important early event in oral carcinogenesis and may predict unfavorable prognosis in OSCC.

Structure-based identification of a new IAP-targeting compound that induces cancer cell death inducing NF-κB pathway.

Inhibitors of apoptosis proteins (IAPs) are validated onco-targets, as their overexpression correlates with cancer onset, progression, diffusion and chemoresistance. IAPs regulate cell death survival pathways, inflammation, and immunity. Targeting IAPs, by impairing their protein-protein interaction surfaces, can affect events occurring at different stages of cancer development. To this purpose, we employed a rational virtual screening approach to identify compounds predicted to interfere with the assembly of pro-survival macromolecular complexes. One of the candidates, FC2, was shown to bind in vitro the BIR1 domains of both XIAP and cIAP2. Moreover, we demonstrated that FC2 can induce cancer cell death as a single agent and, more potently, in combination with the Smac-mimetic SM83 or with the cytokine TNF. FC2 determined a prolonged activation of the NF-κB pathway, accompanied to a stabilization of XIAP-TAB1 complex. This candidate molecule represents a valuable lead compound for the development of a new class of IAP-antagonists for cancer treatment.

Downregulation of inhibitor of apoptosis protein induces apoptosis and suppresses stemness maintenance in testicular teratoma.

Inhibitors of apoptosis (IAPs) are a family of cell death inhibitors found in viruses and metazoans that physically interact with a variety of pro-apoptotic proteins and inhibit apoptosis induced by diverse stimuli. Melanoma IAP (ML-IAP) is a potent anti-apoptotic protein that is strongly upregulated in melanoma and confers protection against a variety of pro-apoptotic stimuli. In the present study, it was revealed that ML-IAP was expressed at high levels in testicular teratoma. Deletion and mutational analysis demonstrated that ML-IAP silencing significantly decreased P19 cell proliferation while inducing cell cycle arrest and apoptosis. ML-IAP knockdown significantly induced caspase-3/8/9-mediated apoptosis in P19 cells. In addition, metabolism and stemness maintenance in P19 cells were suppressed by ML-IAP knockdown. These results indicated that ML-IAP silencing is a powerful inducer of apoptosis mediated by cell death receptors and may function as a direct activator of downstream effector caspases.

Development of a protein signature to enable clinical positioning of IAP inhibitors in colorectal cancer.

Resistance to chemotherapy-induced cell death is a major barrier to effective treatment of solid tumours such as colorectal cancer, CRC. Herein, we present a study aimed at developing a proteomics-based predictor of response to standard-of-care (SoC) chemotherapy in combination with antagonists of IAPs (inhibitors of apoptosis proteins), which have been implicated as mediators of drug resistance in CRC. We quantified the absolute expression of 19 key apoptotic proteins at baseline in a panel of 12 CRC cell lines representative of the genetic diversity seen in this disease to identify which proteins promote resistance or sensitivity to a model IAP antagonist [birinapant (Bir)] alone and in combination with SoC chemotherapy (5FU plus oxaliplatin). Quantitative western blotting demonstrated heterogeneous expression of IAP interactome proteins across the CRC cell line panel, and cell death analyses revealed a widely varied response to Bir/chemotherapy combinations. Baseline protein expression of cIAP1, caspase-8 and RIPK1 expression robustly correlated with response to Bir/chemotherapy combinations. Classifying cell lines into 'responsive', 'intermediate' and 'resistant' groups and using linear discriminant analysis (LDA) enabled the identification of a 12-protein signature that separated responders to Bir/chemotherapy combinations in the CRC cell line panel with 100% accuracy. Moreover, the LDA model was able to predict response accurately when cells were cocultured with Tumour necrosis factor-alpha to mimic a pro-inflammatory tumour microenvironment. Thus, our study provides the starting point for a proteomics-based companion diagnostic that predicts response to IAP antagonist/SoC chemotherapy combinations in CRC.

The mechanism by which Ginkgo biloba extract induces the apoptosis of human laryngeal cancer Hep-2 cells by reducing reactive oxygen species level and activating JNK signaling pathway / 中国基层医药

Objective:To investigate the apoptosis-inducing effect of Ginkgo biloba extract (Ginaton) on human laryngeal cancer Hep-2 cells and the underlying molecular mechanism.Methods:Human laryngeal cancer Hep-2 cells were cultured in vitro and human laryngeal cancer Hep-2 cells in the log phase were treated with Ginaton in time and concentration gradients. The cell counting kit-8 (CCK-8) assay was performed to investigate the inhibitory effects of Ginaton on Hep-2 cells. Flow cytometry was performed to detect apoptosis and determine the level of reactive oxygen species (ROS). Western blot assay was performed to detect apoptosis and signaling pathway-related protein expression. Results:Ginaton inhibited the proliferation of Hep-2 cells in a time-dependent and concentration-dependent manner. Malondialdehyde level decreased gradually in a time-dependent manner, and decreased to 2.98 μmol/g after 24 hours of Ginaton treatment. Superoxide dismutase level increased gradually in a time-dependent manner and increased to 90.35 U/g after 24 hours of Ginaton treatment. ROS level decreased gradually in a time-dependent manner and deceased to 18.7% of the level before treatment after 24 hours of Ginaton treatment. There was no significant difference in ROS level between before and after 24 hours of Ginaton treatment ( F = 14.98, 19.65, 11.47, all P < 0.001). After 3, 6, 12 and 24 hours of Ginaton treatment, the expression of phosphorylated N-terminal protein kinase increased to 1.98, 2.57, 2.91 and 3.28 in a time-dependent manner. There was significant difference in the expression of phosphorylated N-terminal protein kinase between before treatment and after 3, 6, 12 and 24 hours of Ginaton treatment ( F = 16.37, P < 0.001). Conclusion:Ginaton can effectively inhibit the proliferation and induce apoptosis of human laryngeal cancer Hep-2 cells in vitro, which may be related to regulating ROS level and activating JNK signaling pathway.

YM155 Reverses Cabazitaxel Resistance in Castration-resistant Prostate Cancer by Reducing Survivin Expression.

BACKGROUND/AIM: The purpose of the present study was to clarify whether treatment with YM155, a novel small-molecule inhibitor of survivin, reversed cabazitaxel resistance in castration-resistant prostate cancer (CRPC). MATERIALS AND METHODS: Cabazitaxel resistance was induced in the castration-resistant prostate cancer cell line, 22Rv1-CR. In vitro and in vivo models were used to test the efficacy of YM155 and cabazitaxel. RESULTS: Survivin gene expression was significantly higher in 22Rv1-CR than its parent cells (22Rv1). In 22Rv1-CR cells, YM155 significantly reduced expression of the survivin gene in a concentration-dependent manner. YM155 alone was poorly effective; however, it significantly enhanced the anticancer effects of cabazitaxel on 22Rv1-CR in vitro and in vivo. CONCLUSION: Inhibition of survivin by YM155 overcomes cabazitaxel resistance in CRPC cells.

Survivin modulation in the antimelanoma activity of prodiginines.

Melanoma is a type of skin cancer with an elevated incidence of metastasis and chemoresistance. Such features hamper treatment success of these neoplasms, demanding the search for new therapeutic options. Using a two-step resin-based approach, we recently demonstrated that cytotoxic prodiginines bind to the inhibitor of apoptosis protein, survivin. Herein, we explore the role of survivin in melanoma and whether its modulation is related to the antimelanoma properties of three cytotoxic prodiginines (prodigiosin, cyclononylprodigiosin, and nonylprodigiosin) isolated from marine bacteria. In melanoma patients and cell lines, survivin is overexpressed, and higher levels negatively impact survival. All three prodiginines caused a decrease in cell growth with reduced cytotoxicity after 24 h compared to 72 h treatment, suggesting that low concentrations promote cytostatic effects in SK-Mel-19 (BRAF mutant) and SK-Mel-28 (BRAF mutant), but not in SK-Mel-147 (NRAS mutant). An increase in G1 population was observed after 24 h treatment with prodigiosin and cyclononylprodigiosin in SK-Mel-19. Further studies indicate that prodigiosin induced apoptosis and DNA damage, as detected by increased caspase-3 cleavage and histone H2AX phosphorylation, further arguing for the downregulation of survivin. Computer simulations suggest that prodigiosin and cyclononylprodigiosin bind to the BIR domain of survivin. Moreover, knockdown of survivin increased long-term toxicity of prodigiosin, as observed by reduced clonogenic capacity, but did not alter short-term cytotoxicity. In summary, prodiginine treatment provoked cytostatic rather than cytotoxic effects, cell cycle arrest at G0/G1 phase, induction of apoptosis and DNA damage, downregulation of survivin, and decreased clonogenic capacity in survivin knockdown cells.