Distinct roles for the cellular inhibitors of apoptosis proteins 1 and 2

Evasion of apoptosis and treatment resistance in squamous cell carcinoma of the head and neck

Combinations of surgery, radiotherapy and chemotherapy can eradicate tumors in patients with locally advanced squamous cell carcinoma of the head and neck (LA SCCHN), but a significant proportion of tumors progress, recur, or do not respond to therapy due to treatment resistance. The prognosis for these patients is poor, thus new approaches are needed to improve outcomes. Key resistance mechanisms to chemoradiotherapy (CRT) in patients with LA SCCHN are alterations to the pathways that mediate apoptosis, a form of programmed cell death. Targeting dysregulation of apoptotic pathways represents a rational therapeutic strategy in many types of cancer, with a number of proteins, including the pro-survival B-cell lymphoma 2 family and inhibitors of apoptosis proteins (IAPs), having been identified as druggable targets. This review discusses the mechanisms by which apoptosis occurs under physiological conditions, and how this process is abnormally restrained in LA SCCHN tumor cells, with treatment strategies aimed at re-enabling apoptosis in LA SCCHN also considered. In particular, the development of, and future opportunities for, IAP inhibitors in LA SCCHN are discussed, in light of recent encouraging proof-of-concept clinical trial data.

Proteomics analysis of immune response-related proteins in Guillain-Barré Syndrome (GBS) and Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)

The objective is to characterize differentially expressed proteins (DEPs) in Guillain-Barré Syndrome (GBS) and Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) through high-throughput analysis. Sera from 11 healthy controls (HCs), 21 GBS and 19 CIDP patients were subjected to Olink Proteomics Analysis. In the comparison between CIDP and GBS groups, up-regulation of ITM2A and down-regulation of NTF4 were observed. Comparing GBS with HCs revealed 18 up-regulated and 4 down-regulated proteins. Comparing CIDP with the HCs identified 15 up-regulated and 4 down-regulated proteins. Additionally, the correlation between clinical characteristics and DEPs were uncovered. In conclusion, the DEPs have significant potential to advance our understanding of the pathogenesis in these debilitating neurological disorders.

Stable RNA G-Quadruplex in the 5'-UTR of Human cIAP1 mRNA Promotes Translation in an IRES-Independent Manner

RNA G-quadruplex (rG4) structures can influence the fate and functions of mRNAs, especially the translation process. The presence of rG4 structures in 5'-untranslated regions (5'-UTRs) of mRNAs generally represses translation. However, rG4 structures can also promote internal ribosome entry site (IRES)-mediated translation as one of its determinants. Here, we report the identification of an evolutionary conserved rG4-forming sequence motif at the extreme 5'-end of the unusually long 5'-UTR (1.7 kb) in the transcript of human cIAP1 gene encoding the cellular inhibitor of apoptosis protein-1 that promotes cell survival by suppressing apoptosis and is overexpressed in various cancer cells. Expectedly, NMR study, CD spectroscopy, and UV melting assay confirm the formation of a potassium ion-dependent intramolecular and parallel rG4 structure at the sequence stretch. Moreover, the G4-RNA-specific precipitation using biotin-linked biomimetic BioCyTASQ validates the formation of the rG4 structure in the cIAP1 5'-UTR in cells. Interestingly, disruption of the rG4 structure in the cIAP1 5'-UTR results in a dramatic reduction in translation of the downstream luciferase reporter in cells, suggesting a translation-promoting effect of the rG4 structure, contrary to many earlier reports. Furthermore, enhancement of translation by the cIAP1 rG4 structure occurs in an IRES-independent manner.

The Effect of Xevinapant Combined with Ionizing Radiation on HNSCC and Normal Tissue Cells and the Impact of Xevinapant on Its Targeted Proteins cIAP1 and XIAP

The poor prognosis of HNSCC is partly due to treatment resistance. The SMAC mimetic Xevinapant is a promising new approach to targeted cancer therapy. Xevinapant inhibits cIAP1/2 and XIAP, leading to apoptosis, necroptosis and inhibition of prosurvival signaling. Combining Xevinapant with IR could improve therapeutic potential. The effect of Xevinapant in combination with IR on HNSCC and healthy tissue cells was investigated. Cell growth, cell death, clonogenic survival and DNA double-strand breaks (DSBs) were studied, and intracellular cIAP1 and XIAP levels were evaluated. Xevinapant had cytostatic and cytotoxic, as well as radiosensitizing, effects on the malignant cells, while healthy tissue cells were less affected. Apoptotic and necrotic cell death was particularly affected, but the increase in residual DSBs and the reduced survival implied an additional effect of Xevinapant on DNA damage repair and other cell inactivation mechanisms. cIAP1 and XIAP levels varied for each cell line and were affected by Xevinapant and IR treatment. There was an association between higher IAP levels and increased cell death. Xevinapant appears to be a potent new drug for HNSCC therapy, especially in combination with IR. IAP levels could be an indicator for impaired DNA damage repair and increased susceptibility to cellular stress.

Differential regulation of BIRC2 and BIRC3 expression by inflammatory cytokines and glucocorticoids in pulmonary epithelial cells

Roles for the baculoviral inhibitor of apoptosis repeat-containing (BIRC) genes, BIRC2 and BIRC3, may include signaling to the inflammatory transcription factor, nuclear factor-κB (NF-κB) and protection from cell death. However, distinct functions for each BIRC are not well-delineated. Given roles for the epithelium in barrier function and host defence, BIRC2 and BIRC3 expression was characterized in pulmonary epithelial cell lines and primary human bronchial epithelial cells (pHBECs) grown as undifferentiated cells in submersion culture (SC) or as highly differentiated cells at air-liquid interface (ALI). In A549 cells, interleukin-1β (IL1B) and tumor necrosis factor α (TNF) induced BIRC3 mRNA (~20-50-fold), with maximal protein expression from 6-24 h. Similar effects occurred in BEAS-2B and Calu-3 cells, as well as SC and ALI pHBECs. BIRC2 protein was readily detected in unstimulated cells, but was not markedly modulated by IL1B or TNF. Glucocorticoids (dexamethasone, budesonide) modestly increased BIRC3 mRNA and protein, but showed little effect on BIRC2 expression. In A549 cells, BIRC3 mRNA induced by IL1B was unchanged by glucocorticoids and showed supra-additivity with TNF-plus-glucocorticoid. Supra-additivity was also evident for IL1B-plus-budesonide induced-BIRC3 in SC and ALI pHBECs. Using A549 cells, IL1B- and TNF-induced BIRC3 expression, and to a lesser extent, BIRC2, was prevented by NF-κB inhibition. Glucocorticoid-induced BIRC3 expression was prevented by silencing and antagonism of the glucocorticoid receptor. Whereas TNF, but not IL1B, induced degradation of basal BIRC2 and BIRC3 protein, IL1B- and TNF-induced BIRC3 protein remained stable. Differential regulation by cytokines and glucocorticoids shows BIRC2 protein expression to be consistent with roles in rapid signaling events, whereas cytokine-induced BIRC3 may be more important in later effects. While TNF-induced degradation of both BIRCs may restrict their activity, cytokine-enhanced BIRC3 expression could prime for its function. Finally, shielding from glucocorticoid repression, or further enhancement by glucocorticoid, may indicate a key protective role for BIRC3.

Extended follow-up of a phase 2 trial of xevinapant plus chemoradiotherapy in high-risk locally advanced squamous cell carcinoma of the head and neck: a randomised clinical trial

INTRODUCTION

We report long-term efficacy and overall survival (OS) results from a randomised, double-blind, phase 2 study (NCT02022098) investigating xevinapant plus standard-of-care chemoradiotherapy (CRT) vs. placebo plus CRT in 96 patients with unresected locally advanced squamous cell carcinoma of the head and neck (LA SCCHN).

METHODS

Patients were randomised 1:1 to xevinapant 200 mg/day (days 1-14 of a 21-day cycle for 3 cycles), or matched placebo, plus CRT (cisplatin 100 mg/m² every 3 weeks for 3 cycles plus conventional fractionated high-dose intensity-modulated radiotherapy [70 Gy/35 F, 2 Gy/F, 5 days/week for 7 weeks]). Locoregional control, progression-free survival, and duration of response after 3 years, long-term safety, and 5-year OS were assessed.

RESULTS

The risk of locoregional failure was reduced by 54% for xevinapant plus CRT vs. placebo plus CRT but did not reach statistical significance (adjusted hazard ratio [HR] 0.46; 95% CI, 0.19-1.13; P = .0893). The risk of death or disease progression was reduced by 67% for xevinapant plus CRT (adjusted HR 0.33; 95% CI, 0.17-0.67; P = .0019). The risk of death was approximately halved in the xevinapant arm compared with placebo (adjusted HR 0.47; 95% CI, 0.27-0.84; P = .0101). OS was prolonged with xevinapant plus CRT vs. placebo plus CRT; median OS not reached (95% CI, 40.3-not evaluable) vs. 36.1 months (95% CI, 21.8-46.7). Incidence of late-onset grade ≥3 toxicities was similar across arms.

CONCLUSIONS

In this randomised phase 2 study of 96 patients, xevinapant plus CRT demonstrated superior efficacy benefits, including markedly improved 5-year survival in patients with unresected LA SCCHN.

Divergent effect of Birinapant, and BV6 SMAC mimetic on TNFα induced NF-κB signaling and cell viability in activated hepatic stellate cells

BACKGROUND

Tumor necrosis factor-α (TNFα) is a pleiotropic cytokine involved in nuclear factor kappa B (NF-κB) mediated cell survival as well as cell death. High serum TNFα levels correlate with liver fibrosis and enhance hepatic stellate cell (HSC) viability. However, the regulatory role of cellular inhibitor of apoptosis-1/2 (cIAP1/2) during TNFα induced NF-κB signaling in activated HSCs is largely unknown.

METHOD AND RESULTS

Activated HSCs were treated with cIAP1/2 inhbitiors i.e., SMAC mimetic BV6, and Birinapant in the presence of TNFα and macrophage conditioned media. TNFα cytokine increased cIAP2 expression and enhanced cell viability through the canonical NF-κB signaling in activated HSCs. cIAP2 inhibition via BV6 decreased the TNFα induced canonical NF-κB signaling, and reduced cell viability in activated HSCs. SMAC mimetic, Birinapant alone did not affect the cell viability but treatment of TNFα sensitized HSCs with Birinapant induced cell death. While BV6 mediated cIAP2 ablation was able to decrease the TNFα induced canonical NF-κB signaling, this effect was not observed with Birinapant treatment. Secreted TNFα from M1 polarized macrophages sensitized activated HSCs to BV6 or Birinapant mediated cell death. However, M2 polarized macrophage conditioned medium rescued the activated HSCs from BV6 mediated cytotoxicity.

CONCLUSION

In this study, we describe the regulatory role of cIAP2 in TNFα induced NF-κB signaling in activated HSCs. Targeting cIAP2 may be a promising approach for liver fibrosis treatment via modulating NF-κB signaling in activated HSCs.

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.

Inhibiting the inhibitors: Development of the IAP inhibitor xevinapant for the treatment of locally advanced squamous cell carcinoma of the head and neck

Standard of care for patients with locally advanced squamous cell carcinoma of the head and neck (LA SCCHN) is surgery followed by chemoradiotherapy (CRT) or definitive CRT. However, approximately 50 % of patients with LA SCCHN develop disease recurrence or metastasis within 2 years of completing treatment, and the outcome for these patients is poor. Despite this, the current treatment landscape for LA SCCHN has remained relatively unchanged for more than 2 decades, and novel treatment options are urgently required. One of the key causes of disease recurrence is treatment resistance, which commonly occurs due to cancer cells' ability to evade apoptosis. Evasion of apoptosis has been in part attributed to the overexpression of inhibitor of apoptosis proteins (IAPs). IAPs, including X-linked IAP (XIAP) and cellular IAP 1 and 2 (cIAP1/2), are a class of proteins that regulate apoptosis induced by intrinsic and extrinsic apoptotic pathways. IAPs have been shown to be overexpressed in SCCHN, are associated with poor clinical outcomes, and are, therefore, a rational therapeutic target. To date, several IAP inhibitors have been investigated; however, only xevinapant, a potent, oral, small-molecule IAP inhibitor, has shown clinical proof of concept when combined with CRT. Specifically, xevinapant demonstrated superior efficacy in combination with CRT vs placebo + CRT in a randomized, double-blind, phase 2 trial in patients with unresected LA SCCHN. Here, we describe the current treatment landscape in LA SCCHN and provide the rationale for targeting IAPs and the clinical data reported for xevinapant.

Autoimmunity to a ribonucleoprotein drives neuron loss in multiple sclerosis models

Neurodegeneration, the progressive loss or damage to neurons and axons, underlies permanent disability in multiple sclerosis (MS); yet its mechanisms are incompletely understood. Recent data indicates autoimmunity to several intraneuronal antigens, including the RNA binding protein (RBP) heterogenous nuclear ribonucleoprotein A1 (hnRNP A1), as contributors to neurodegeneration. We previously showed that addition of anti-hnRNP A1 antibodies, which target the same immunodominant domain of MS IgG, to mice with experimental autoimmune encephalomyelitis (EAE) worsened disease and resulted in an exacerbation of hnRNP A1 dysfunction including cytoplasmic mislocalization of hnRNP A1, stress granule (SG) formation and neurodegeneration in the chronic stages of disease. Because this previous study focused on a singular timepoint during EAE, it is unclear whether anti-hnRNP A1 antibody induced hnRNP A1 dysfunction caused neurodegeneration or was result of it. In the present study, we analyzed in vivo and in vitro models of anti-hnRNP A1 antibody-mediated autoimmunity for markers of hnRNP A1 dysfunction and neurodegeneration over a time course to gain a better understanding of the connection between hnRNP A1 dysfunction and neurodegeneration. Anti-hnRNP A1 antibody treatment resulted in increased neuronal hnRNP A1 mislocalization and nuclear depletion temporally followed by altered RNA expression and SG formation, and lastly an increase in necroptotic signalling and neuronal cell death. Treatment with necrostatin-1s inhibited necroptosis and partially rescued anti-hnRNP A1 antibody-mediated neurodegeneration while clathrin knockdown specifically inhibited anti-hnRNP A1 antibody uptake into neurons. This data identifies a novel antibody-mediated mechanism of neurodegeneration, which may be targeted to inhibit neurodegeneration and prevent permanent neurological decline in persons living with MS.

Inhibitors of apoptosis: expression and regulation in the endometrium during the estrous cycle and at the maternal-conceptus interface during pregnancy in pigs

Objective

Caspase-mediated apoptosis plays a crucial role in the regulation of endometrial and placental function in females. Caspase activity is tightly controlled by members of the inhibitors of apoptosis proteins (IAPs) family. However, the expression and regulation of IAPs at the maternal-conceptus interface has not been studied in pigs. Therefore, we determined the expression of IAP family members baculovirus IAP repeat-containing 1 (BIRC1) to BIRC6 at the maternal-conceptus interface in pigs.

Methods

We obtained endometrial tissues from pigs at various stages of the estrous cycle and pregnancy, conceptus tissues during early pregnancy, and chorioallantoic tissues during mid- to late pregnancy and analyzed the expression of IAPs. Furthermore, we determined the effects of the steroid hormones estradiol-17β (E2) and progesterone on the expression of IAPs in endometrial explant tissue cultures.

Results

During the estrous cycle, BIRC2 and BIRC5 expression varied cyclically, and during pregnancy, endometrial BIRC1, BIRC2, BIRC3, BIRC4, and BIRC5 expression varied in a stage-specific manner. Conceptus and chorioallantoic tissues also expressed IAPs during pregnancy. The BIRC2 and BIR3 mRNAs were localized to luminal epithelial cells, and BIRC4 proteins to glandular epithelial cells in the endometrium. Exposure of endometrial tissues to E2 increased the expression of BIRC6, while progesterone increased the expression of BIRC1, BIRC4, and BIRC6 in a dose-dependent manner.

Conclusion

These results indicated that IAPs were expressed in the endometrium during the estrous cycle and at the maternal-conceptus interface during pregnancy in a stage-specific manner. In addition, steroid hormones were found to be responsible for the expression of some IAPs in pigs. Together, the results suggested that IAPs may play important roles in endometrial and placental functions by regulating caspase action and apoptosis at the maternal-conceptus interface.

Hyaluronic acid is a negative regulator of mucosal fibroblast-mediated enhancement of HIV infection

The majority of HIV infections are established through the genital or rectal mucosa. Fibroblasts are abundant in these tissues, and although not susceptible to infection, can potently enhance HIV infection of CD4+ T cells. Hyaluronic acid (HA) is a major component of the extracellular matrix of fibroblasts, and its levels are influenced by the inflammatory state of the tissue. Since inflammation is known to facilitate HIV sexual transmission, we investigated the role of HA in genital mucosal fibroblast-mediated enhancement of HIV infection. Depletion of HA by CRISPR-Cas9 in primary foreskin fibroblasts augmented the ability of the fibroblasts to increase HIV infection of CD4+ T cells. This amplified enhancement required direct contact between the fibroblasts and CD4+ T cells, and could be attributed to both increased rates of trans-infection and the increased ability of HA-deficient fibroblasts to push CD4+ T cells into a state of higher permissivity to infection. This HIV-permissive state was characterized by differential expression of genes associated with regulation of cell metabolism and death. Our results suggest that conditions resulting in diminished cell-surface HA on fibroblasts, such as genital inflammation, can promote HIV transmission by conditioning CD4+ T cells toward a state more vulnerable to infection by HIV.

Transcription Analysis of the Chemerin Impact on Gene Expression Profile in the Luteal Cells of Gilts

Chemerin is a recently discovered adipokine that participates in the regulation of many physiological and disorder-related processes in mammals, including metabolism, inflammatory reactions, obesity, and reproduction. We investigated how chemerin affects the transcriptome profile of porcine luteal cells. The luteal cells were acquired from mature gilts. After the in vitro culturing with and without chemerin, the total RNAs were isolated and high-throughput sequencing was performed. Obtained datasets were processed using bioinformatic tools. The study revealed 509 differentially expressed genes under the chemerin influence. Their products take part in many processes, important for the functions of the corpus luteum, such as steroids and prostaglandins synthesis, NF-κB and JAK/STAT signal transducing pathways, and apoptosis. The expression of the CASP3, HSD3B7, IL1B, and PTGS2 genes, due to their important role in the physiology of the corpus luteum, was validated using the quantitative real-time polymerase chain reaction (qPCR) method. The qPCR confirmed the changes of gene expression. Chemerin in physiological concentrations significantly affects the expression of many genes in luteal cells of pigs, which is likely to result in modification of physiological processes related to reproduction.

The effects of acupuncture and electroacupuncture on Parkinson's disease: Current status and future perspectives for molecular mechanisms

Among the progressive neurodegenerative disorders, Parkinson's disease (PD) is the second most common. Different factors have critical role in pathophysiology of PD such as apoptosis pathways, inflammatory cytokines, oxidative stress, and neurotransmitters and its receptors abnormalities. Acupuncture and electroacupuncture were considered as nondrug therapies for PD. Although numerous studies has been conducted for assessing the mechanism underlying electroacupuncture and acupuncture, various principal aspects of these treatment procedures remain not well-known. There have also been few investigations on the molecular mechanism of acupuncture and electroacupuncture therapy effects in PD. This review evaluates the effects of electroacupuncture and acupuncture on the molecular mechanism in PD.

Inhibitor of apoptosis proteins, NAIP, cIAP1 and cIAP2 expression during macrophage differentiation and M1/M2 polarization

Monocytes and macrophages constitute the first line of defense of the immune system against external pathogens. Macrophages have a highly plastic phenotype depending on environmental conditions; the extremes of this phenotypic spectrum are a pro-inflammatory defensive role (M1 phenotype) and an anti-inflammatory tissue-repair one (M2 phenotype). The Inhibitor of Apoptosis (IAP) proteins have important roles in the regulation of several cellular processes, including innate and adaptive immunity. In this study we have analyzed the differential expression of the IAPs, NAIP, cIAP1 and cIAP2, during macrophage differentiation and polarization into M1 or M2. In polarized THP-1 cells and primary human macrophages, NAIP is abundantly expressed in M2 macrophages, while cIAP1 and cIAP2 show an inverse pattern of expression in polarized macrophages, with elevated expression levels of cIAP1 in M2 and cIAP2 preferentially expressed in M1. Interestingly, treatment with the IAP antagonist SMC-LCL161, induced the upregulation of NAIP in M2, the downregulation of cIAP1 in M1 and M2 and an induction of cIAP2 in M1 macrophages.

The changing 50% inhibitory concentration (IC50) of cisplatin: a pilot study on the artifacts of the MTT assay and the precise measurement of density-dependent chemoresistance in ovarian cancer

Inconsistencies in the half-maximal (50%) inhibitory concentration (IC50) data for anticancer chemotherapeutic agents have yielded irreproducible experimental results and thus reciprocally contradictory theories in modern cancer research. The MTT assay is currently the most extensively used method for IC50 measurements. Here, we dissected the critical reasons behind MTT-dependent IC50 inconsistencies. We showed that IC50 errors caused by the technical deficiencies of the MTT assay are large and not adjustable (range: 300-11,000%). To overcome severe MTT artifacts, we developed an unbiased direct IC50 measurement method, the limiting dilution assay. This detection technique led us to the discovery of the inherent density-dependent chemoresistance variation of cancer cells, which is manifold and unpredictable in its forms. The subsequent intracellular signaling pathway analysis indicated that pAkt and p62 expression levels correlated with alterations in the IC50 values for cisplatin in ovarian cancer, providing an explainable mechanism for this property. An in situ pAkt-and-p62-based immunohistochemical (IHCpAkt+p62) scoring system was thereby established. Both the limiting dilution assay and the IHCpAkt+p62 scoring system accurately predicted the primary chemoresistance against cisplatin in ovarian cancer patients. Furthermore, two distinct chemoresistant recurrence patterns were uncovered using these novel detection tools, which were linked to two different forms of density-chemoresistance relationships (positively vs. negatively correlated), respectively. An interpretation was given based on the cancer evolution theory. We concluded that the density-related IC50 uncertainty is a natural property of the cancer cells and that the precise measurement of the density-dependent IC50 spectrum can benefit both basic and clinical cancer research fields.

Metabolic profiling of human CD4+ cells following treatment with methotrexate and anti-TNF-α infliximab

The autoimmune process in rheumatoid arthritis depends on activation of immune cells, which utilize intracellular kinases to respond to external stimuli such as cytokines, immune complexes, and antigens. CD4+ T cells comprise a large proportion of the inflammatory cells that invade the synovial tissue and may therefore be a cell type of pathogenic importance. Both methotrexate and infliximab are effective in the treatment of inflammatory arthritis; however, the biological effects triggered by these treatments and the biochemical mechanisms underlining the cell response are still not fully understood. Thus, in this study the global metabolic changes associated with methotrexate or infliximab treatment of isolated human CD4+ T cells were examined using gas chromatography/mass spectrometry or liquid chromatography/mass spectrometry. In total 148 metabolites involved in selective pathways were found to be significantly altered. Overall, the changes observed are likely to reflect the effort of CD4+ cells to increase the production of cellular reducing power to offset the cellular stress exerted by treatment. Importantly, analysis of the global metabolic changes associated with MTX or infliximab treatment of isolated human CD4+ T cells suggested that the toxicity associated with these agents is minimal when used at clinically relevant concentrations.

c-IAP1 and c-IAP2 redundancy differs between T and B cells

Cellular Inhibitors of Apoptosis 1 and 2 (c-IAP1 and c-IAP2) are ubiquitin protein ligases (E3s) that constitutively ubiquitinate and induce proteasomal-mediated degradation of NF-κB Inducing Kinase (NIK) and repress non-canonical NF-κB activation. Mice expressing an E3-inactive c-IAP2 mutant (c-IAP2(H570A)) have constitutive activation of non-canonical NF-κB, resulting in B cell hyperplasia and T cell costimulation-independence. If, and if so to what extent, c-IAP1 and c-IAP2 are redundant in NF-κB regulation in these mice is not known. Here we have generated mice expressing a mutant c-IAP1 that lacks E3 activity (c-IAP1(H582A)). These mice were phenotypically normal and did not have constitutive NF-κB activation in B cells or MEFs. siRNA-mediated knockdown of c-IAP2 showed that accumulated c-IAP2, resulting from lack of c-IAP1-dependent degradation, compensated for absent c-IAP1 E3 activity. Surprisingly, c-IAP1(H582A) T cells had a lower p100/p52 ratio than wild type T cells, and in the absence of costimulation proliferated to a degree intermediate between wild type and c-IAP2(H570A) T cells. Therefore, although c-IAP1 and c-IAP2 both can repress constitutive NF-κB activation, the relative importance of each varies according to cell type.

Anti-apoptotic proteins on guard of melanoma cell survival

Apoptosis plays a pivotal role in sustaining proper tissue development and homeostasis. Evading apoptosis by cancer cells is a part of their adaption to microenvironment and therapies. Cellular integrity is predominantly maintained by pro-survival members of Bcl-2 family and IAPs. Melanoma cells are characterized by a labile and stage-dependent phenotype. Pro-survival molecules can protect melanoma cells from apoptosis and mediate other processes, thus enhancing aggressive phenotype. The essential role of Bcl-2, Mcl-1, Bcl-X(L), livin, survivin and XIAP was implicated for melanoma, often in a tumor stage-dependent fashion. In this review, the current knowledge of pro-survival machinery in melanoma is discussed.

Novel transglutaminase 1 mutations in patients affected by lamellar ichthyosis

Lamellar Ichthyosis (LI) is a form of congenital ichthyosis that is caused by mutations in the TGM1 gene that encodes for the transglutaminase 1 (TG1) enzyme. Functional inactivation of TG1 could be due to mutations, deletion or insertions. In this study, we have screened 16 patients affected by LI and found six new mutations: two transition/transversion (R37G, V112A), two nonsense mutations and two putative splice site both leading to a premature stop codon. The mutations are localized in exons 2 (N-terminal domain), 5, 11 (central catalytic domain), and none is located in the two beta-barrel C-terminal domains. In conclusion, this study expands the current knowledge on TGM1 mutation spectrum, increasing the characterization of mutations would provide more accurate prenatal genetic counselling for parents at-risk individuals.

Caloric restriction: is mammalian life extension linked to p53?

Caloric restriction, that is limiting food intake, is recognized in mammals as the best characterized and most reproducible strategy for extending lifespan, retarding physiological aging and delaying the onset of age-associated diseases. The aim of this mini review is to argue that p53 is the connection in the abilities of both the Sirt-1 pathway and the TOR pathway to impact on longevity of cells and organisms. This novel, lifespan regulating function of p53 may be evolutionarily more ancient than its relatively recent role in apoptosis and tumour suppression, and is likely to provide many new insights into lifespan modulation.

Cell death pathology: the war against cancer

Programmed cell death was a fundamental discovery, awarded with the Nobel price in 2002 to Sulston, Brenner and Horvitz. Since then it has been clear that alteration of apoptotic pathways is a common feature of tumors, enabling cancer cells to survive chemotherapeutic interventions. Thus, apoptosis is an attractive target in cancer therapy, with the aim to revert the cancer-related alterations of the cell death machinery. Here, we overview the fundamental apoptotic pathways and summarize the attempts to target apoptosis to restore cell death in cancer cells with a special focus on the p53-family and autophagy.