BNIP3L

Gene Summary

Gene:BNIP3L; BCL2 interacting protein 3 like
Aliases: NIX, BNIP3a
Location:8p21.2
Summary:This gene encodes a protein that belongs to the pro-apoptotic subfamily within the Bcl-2 family of proteins. The encoded protein binds to Bcl-2 and possesses the BH3 domain. The protein directly targets mitochondria and causes apoptotic changes, including loss of membrane potential and the release of cytochrome c. [provided by RefSeq, Feb 2015]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:BCL2/adenovirus E1B 19 kDa protein-interacting protein 3-like
Source:NCBIAccessed: 15 March, 2017

Ontology:

What does this gene/protein do?
Show (19)

Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 15 March 2017 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

Tag cloud generated 15 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (4)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: BNIP3L (cancer-related)

Yang XJ, Si RH, Liang YH, et al.
Mir-30d increases intracellular survival of Helicobacter pylori through inhibition of autophagy pathway.
World J Gastroenterol. 2016; 22(15):3978-91 [PubMed] Free Access to Full Article Related Publications
AIM: To determine if mir-30d inhibits the autophagy response to Helicobacter pylori (H. pylori) invasion and increases H. pylori intracellular survival.
METHODS: The expression of mir-30d was detected by quantitative polymerase chain reaction (PCR), and autophagy level was examined by transmission electron microscopy, western blot, and GFP-LC3 puncta assay in human AGS cells and GES-1 cells. Luciferase reporter assay was applied to confirm the specificity of mir-30d regulation on the expression of several core molecules involved in autophagy pathway. The expression of multiple core proteins were analyzed at both the mRNA and protein level, and the intracellular survival of H. pylori after different treatments was detected by gentamicin protection assay.
RESULTS: Autophagy level was increased in AGS and GES-1 cells in response to H. pylori infection, which was accompanied by upregulation of mir-30d expression (P < 0.05, vs no H. pylori infection). In the two gastric epithelial cell lines, mimic mir-30d was found to repress the autophagy process, whereas mir-30d inhibitor increased autophagy response to H. pylori invasion. mir-30d mimic decreased the luciferase activity of wild type reporter plasmids carrying the 3' untranslated region (UTR) of all five tested genes (ATG2B, ATG5, ATG12, BECN1, and BNIP3L), whereas it had no effect on the mutant reporter plasmids. These five genes are core genes of autophagy pathway, and their expression was reduced significantly after mir-30d mimic transfection (P < 0.05, vs control cells without mir-30d mimic treatment). Mir-30d mimic transfection and direct inhibition of autophagy increased the intracellular survival of H. pylori in AGS cells.
CONCLUSION: Mir-30d increases intracellular survival of H. pylori in gastric epithelial cells through inhibition of multiple core proteins in the autophagy pathway.

Lin Z, Li JW, Wang Y, et al.
Abnormal miRNA-30e Expression is Associated with Breast Cancer Progression.
Clin Lab. 2016; 62(1-2):121-8 [PubMed] Related Publications
BACKGROUND: microRNAs (miRNAs) are involved in the regulation of various cellular processes, such as differentiation, proliferation, metabolism, and apoptosis, and they have been implicated in several diseases, including cancers.
METHODS: To assess the role of miRNA in the progression of breast cancer, we performed TaqMan-based miRNA profiling for plasma from patients with breast cancer (n = 53), unrelated diseases (n = 40), or matched healthy controls (n = 40), and for breast tumors or adjacent non-tumors (n = 41).
RESULTS: We selected 18 miRNAs with predicted roles in breast cancer and demonstrated that let-7i (p = 0.019), let-7a (p = 0.02), and miR-650 (p = 0.008) were significantly up-regulated in plasma; miR-21 (p < 0.001) is up-regulated in breast cancer tissue, and miR-30e was down-regulated in both plasma (p < 0.001) and breast cancer tissues (p = 0.004). Plasma miR-30e expression was shown to be statistically associated with age (p = 0.0402) and clinical stage (p = 0.007). However, receiver-operating characteristic curve analyses suggested that miR-30e expression cannot significantly differentiate breast cancer from healthy tissue or plasma. Consistent with a potential role for miR-30e in breast cancer, three predicted targets of miR-30e (RAB11A, BNIP3L, and RAB32) are up-regulated in breast cancer tissue.
CONCLUSIONS: These findings suggest that reduced miR-30e correlates with the clinical stage of breast cancer. It is worthwhile to further explore that the potential role of miR-30e as a tumor suppressor in breast cancer, as well as its potential therapeutic utility.

Demark-Wahnefried W, Nix JW, Hunter GR, et al.
Feasibility outcomes of a presurgical randomized controlled trial exploring the impact of caloric restriction and increased physical activity versus a wait-list control on tumor characteristics and circulating biomarkers in men electing prostatectomy for prostate cancer.
BMC Cancer. 2016; 16:61 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Obesity is associated with tumor aggressiveness and disease-specific mortality for more than 15 defined malignancies, including prostate cancer. Preclinical studies suggest that weight loss from caloric restriction and increased physical activity may suppress hormonal, energy-sensing, and inflammatory factors that drive neoplastic progression; however, exact mechanisms are yet to be determined, and experiments in humans are limited.
METHODS: We conducted a randomized controlled trial among 40 overweight or obese, newly-diagnosed prostate cancer patients who elected prostatectomy to explore feasibility of a presurgical weight loss intervention that promoted a weight loss of roughly one kg. week(-1) via caloric restriction and physical activity, as well as to assess effects on tumor biology and circulating biomarkers. Measures of feasibility (accrual, retention, adherence, and safety) were primary endpoints. Exploratory aims were directed at the intervention's effect on tumor proliferation (Ki-67) and other tumor markers (activated caspase-3, insulin and androgen receptors, VEGF, TNFβ, NFκB, and 4E-BP1), circulating biomarkers (PSA, insulin, glucose, VEGF, TNFβ, leptin, SHBG, and testosterone), lymphocytic gene expression of corresponding factors and cellular bioenergetics in neutrophils, and effects on the gut microbiome. Consenting patients were randomized in a 1:1 ratio to either: 1) weight loss via a healthful, guidelines-based diet and exercise regimen; or 2) a wait-list control. While biological testing is currently ongoing, this paper details our methods and feasibility outcomes.
RESULTS: The accrual target was met after screening 101 cases (enrollment rate: 39.6%). Other outcomes included a retention rate of 85%, excellent adherence (95%), and no serious reported adverse events. No significant differences by age, race, or weight status were noted between enrollees vs. non-enrollees. The most common reasons for non-participation were "too busy" (30%), medical exclusions (21%), and "distance" (16%).
CONCLUSIONS: Presurgical trials offer a means to study the impact of diet and exercise interventions directly on tumor tissue, and other host factors that are feasible and safe, though modifications are needed to conduct trials within an abbreviated period of time and via distance medicine-based approaches. Pre-surgical trials are critical to elucidate the impact of lifestyle interventions on specific mechanisms that mediate carcinogenesis and which can be used subsequently as therapeutic targets.
TRIAL REGISTRATION: NCT01886677.

Fader CM, Salassa BN, Grosso RA, et al.
Hemin induces mitophagy in a leukemic erythroblast cell line.
Biol Cell. 2016; 108(4):77-95 [PubMed] Related Publications
BACKGROUND INFORMATION: In eukaryotic cells, autophagy is considered a lysosomal catabolic process which participates in the degradation of intracellular components in a vacuolar structure termed autolysosome. This pathway plays a significant role in the erythropoiesis process, contributing to the clearance of some organelles (such as mitochondria) that are not necessary in the mature red blood cells. Nevertheless, the role of autophagy in erythrocyte maturation has not been fully established.
RESULTS: Here, we have demonstrated that hemin (a physiological erythroid maturation stimulator) is able to induce the expression of critical autophagic genes (i.e., Map1a1b (LC3), Beclin-1 gen, Atg5) in an erythroleukemia cell type. We have also shown that hemin increased the size of autophagic vacuoles which were labelled with LC3 and the degradative lysosomal marker dye quenched-bovine serum albumin. In addition, we have determined by Western blot a rise in the lipidated form of the autophagic protein LC3 (i.e., LC3-II) upon hemin treatment. Moreover, we provide evidence that hemin induces mitochondrial membrane depolarisation and that mitochondria sequestration by autophagy requires the active form of the NIX protein.
CONCLUSIONS: We have found that the physiological erythroid maturation stimulator hemin is able to induce mitophagy in K562 cells, and that the autophagy adaptor NIX is necessary for mitophagy progression. K562 cells have been used as a relevant model to determine the possible therapeutic role of new differentiating compounds.
SIGNIFICANCE: It has been proposed that autophagy induction is a feasible new therapeutic key in fighting cancer. Our results suggest that hemin is favoring erythroid maturation by inducing an autophagic response in K562 cells, being a possible therapeutic candidate that may help in the chronic myelogenous leukemia (CML) treatment.

Wilfinger N, Austin S, Scheiber-Mojdehkar B, et al.
Novel p53-dependent anticancer strategy by targeting iron signaling and BNIP3L-induced mitophagy.
Oncotarget. 2016; 7(2):1242-61 [PubMed] Free Access to Full Article Related Publications
This study identifies BNIP3L as the key regulator of p53-dependent cell death mechanism in colon cancer cells targeted by the novel gallium based anticancer drug, KP46. KP46 specifically accumulated into mitochondria where it caused p53-dependent morphological and functional damage impairing mitochondrial dynamics and bioenergetics. Furthermore, competing with iron for cellular uptake, KP46 lowered the intracellular labile iron pools and intracellular heme. Accordingly, p53 accumulated in the nucleus where it activated its transcriptional target BNIP3L, a BH3 only domain protein with functions in apoptosis and mitophagy. Upregulated BNIP3L sensitized the mitochondrial permeability transition and strongly induced PARKIN-mediated mitochondrial clearance and cellular vacuolization. Downregulation of BNIP3L entirely rescued cell viability caused by exposure of KP46 for 24 hours, confirming that early induced cell death was regulated by BNIP3L. Altogether, targeting BNIP3L in wild-type p53 colon cancer cells is a novel anticancer strategy activating iron depletion signaling and the mitophagy-related cell death pathway.

Shinderman-Maman E, Cohen K, Weingarten C, et al.
The thyroid hormone-αvβ3 integrin axis in ovarian cancer: regulation of gene transcription and MAPK-dependent proliferation.
Oncogene. 2016; 35(15):1977-87 [PubMed] Related Publications
Ovarian carcinoma is the fifth common cause of cancer death in women, despite advanced therapeutic approaches. αvβ3 integrin, a plasma membrane receptor, binds thyroid hormones (L-thyroxine, T4; 3,5,3'-triiodo-L-thyronine, T3) and is overexpressed in ovarian cancer. We have demonstrated selective binding of fluorescently labeled hormones to αvβ3-positive ovarian cancer cells but not to integrin-negative cells. Physiologically relevant T3 (1 nM) and T4 (100 nM) concentrations in OVCAR-3 (high αvβ3) and A2780 (low αvβ3) cells promoted αv and β3 transcription in association with basal integrin levels. This transcription was effectively blocked by RGD (Arg-Gly-Asp) peptide and neutralizing αvβ3 antibodies, excluding T3-induced β3 messenger RNA, suggesting subspecialization of T3 and T4 binding to the integrin receptor pocket. We have provided support for extracellular regulated kinase (ERK)-mediated transcriptional regulation of the αv monomer by T3 and of β3 monomer by both hormones and documented a rapid (30-120 min) and dose-dependent (0.1-1000 nM) ERK activation. OVCAR-3 cells and αvβ3-deficient HEK293 cells treated with αvβ3 blockers confirmed the requirement for an intact thyroid hormone-integrin interaction in ERK activation. In addition, novel data indicated that T4, but not T3, controls integrin's outside-in signaling by phosphorylating tyrosine 759 in the β3 subunit. Both hormones induced cell proliferation (cell counts), survival (Annexin-PI), viability (WST-1) and significantly reduced the expression of genes that inhibit cell cycle (p21, p16), promote mitochondrial apoptosis (Nix, PUMA) and tumor suppression (GDF-15, IGFBP-6), particularly in cells with high integrin expression. At last, we have confirmed that hypothyroid environment attenuated ovarian cancer growth using a novel experimental platform that exploited paired euthyroid and severe hypothyroid serum samples from human subjects. To conclude, our data define a critical role for thyroid hormones as potent αvβ3-ligands, driving ovarian cancer cell proliferation and suggest that disruption of this axis may present a novel treatment strategy in this aggressive disease.

Jin Z, Zheng L, Xin X, et al.
Upregulation of forkhead box O3 transcription is involved in C2-ceramide induced apoptosis and autophagy in ovarian cancer cells in vitro.
Mol Med Rep. 2014; 10(6):3099-105 [PubMed] Related Publications
Ceramide is a bioactive lipid which functions as a tumor suppressor, mediating processes such as apoptosis, growth arrest, senescence and differentiation. The effects of ceramide in ovarian cancers have not been well established. The objective of the present study was to investigate the effects of C2‑ceramide treatment in A2780 ovarian cancer cells and its possible molecular mechanism. C2‑ceramide-induced proliferation inhibition was analyzed using an MTT assay and Trypan blue test. Flow cytometry and terminal deoxynucleotidyl transferase dUTP nick end labeling were used to identify the induction of apoptosis. Transmission electron microscopy was used to confirm the formation of autophagosomes. Quantitative polymerase chain reaction was performed to analyze the messenger RNA expression of the autophagy and cell death associated genes and western blotting was used to analyze the protein expression of beclin 1, LC3, Akt, forkhead box O3 (FOXO3) and adenosine monophosphate-activated protein kinase in ovarian cancer cells. It was found that C2‑ceramide inhibited A2780 cell proliferation in a time‑ and dose‑dependent manner and C2‑ceremide induced A2780 cell apoptosis and autophagy. However, C2‑ceramide‑induced autophagy did not result in cell death, but instead protected ovarian cancer cells from apoptosis. Akt inhibition and FOXO3 activation were implicated in C2‑ceramide‑treated ovarian cancer cells. Furthermore, FOXO3 target genes, which were associated with autophagy (MAP1LC3, GABARAP and GABARAPL1) and cell death (BNIP3, BNIP3L, BIM and PUMA), were upregulated. The present study has shown that C2‑ceramide induced apoptosis and autophagy in ovarian cancer cells. FOXO3 transcription was upregulated, which may contribute to C2‑ceramide‑induced apoptosis and autophagy.

Mirzaei MR, Najafi A, Arababadi MK, et al.
Altered expression of apoptotic genes in response to OCT4B1 suppression in human tumor cell lines.
Tumour Biol. 2014; 35(10):9999-10009 [PubMed] Related Publications
OCT4B1 is a newly discovered spliced variant of OCT4 which is primarily expressed in pluripotent and tumor cells. Based on our previous studies, OCT4B1 is significantly overexpressed in tumors, where it endows an anti-apoptotic property to tumor cells. However, the mechanism by which OCT4B1 regulates the apoptotic pathway is not yet elucidated. Here, we investigated the effects of OCT4B1 suppression on the expression alteration of 84 genes involved in apoptotic pathway. The AGS (gastric adenocarcinoma), 5637 (bladder tumor), and U-87MG (brain tumor) cell lines were transfected with OCT4B1 or irrelevant siRNAs. The expression level of apoptotic genes was then quantified using a human apoptosis panel-PCR kit. Our data revealed an almost similar pattern of alteration in the expression profile of apoptotic genes in all three studied cell lines, following OCT4B1 suppression. In general, the expression of more than 54 apoptotic genes (64 % of arrayed genes) showed significant changes. Among these, some up-regulated (CIDEA, CIDEB, TNFRSF1A, TNFRSF21, TNFRSF11B, TNFRSF10B, and CASP7) and down-regulated (BCL2, BCL2L11, TP73, TP53, BAD, TRAF3, TRAF2, BRAF, BNIP3L, BFAR, and BAX) genes had on average more than tenfold gene expression alteration in all three examined cell lines. With some minor exceptions, suppression of OCT4B1 caused upregulation of pro-apoptotic and down-regulation of anti-apoptotic genes in transfected tumor cells. Uncovering OCT4B1 down-stream targets could further elucidate its part in tumorigenesis, and could lead to finding a new approach to combat cancer, based on targeting OCT4B1.

Foulks JM, Carpenter KJ, Luo B, et al.
A small-molecule inhibitor of PIM kinases as a potential treatment for urothelial carcinomas.
Neoplasia. 2014; 16(5):403-12 [PubMed] Free Access to Full Article Related Publications
The proto-oncogene proviral integration site for moloney murine leukemia virus (PIM) kinases (PIM-1, PIM-2, and PIM-3) are serine/threonine kinases that are involved in a number of signaling pathways important to cancer cells. PIM kinases act in downstream effector functions as inhibitors of apoptosis and as positive regulators of G1-S phase progression through the cell cycle. PIM kinases are upregulated in multiple cancer indications, including lymphoma, leukemia, multiple myeloma, and prostate, gastric, and head and neck cancers. Overexpression of one or more PIM family members in patient tumors frequently correlates with poor prognosis. The aim of this investigation was to evaluate PIM expression in low- and high-grade urothelial carcinoma and to assess the role PIM function in disease progression and their potential to serve as molecular targets for therapy. One hundred thirty-seven cases of urothelial carcinoma were included in this study of surgical biopsy and resection specimens. High levels of expression of all three PIM family members were observed in both noninvasive and invasive urothelial carcinomas. The second-generation PIM inhibitor, TP-3654, displays submicromolar activity in pharmacodynamic biomarker modulation, cell proliferation studies, and colony formation assays using the UM-UC-3 bladder cancer cell line. TP-3654 displays favorable human ether-à-go-go-related gene and cytochrome P450 inhibition profiles compared with the first-generation PIM inhibitor, SGI-1776, and exhibits oral bioavailability. In vivo xenograft studies using a bladder cancer cell line show that PIM kinase inhibition can reduce tumor growth, suggesting that PIM kinase inhibitors may be active in human urothelial carcinomas.

Yang C, Jiang L, Zhang H, et al.
Analysis of hypoxia-induced metabolic reprogramming.
Methods Enzymol. 2014; 542:425-55 [PubMed] Related Publications
Hypoxia is a common finding in advanced human tumors and is often associated with metastatic dissemination and poor prognosis. Cancer cells adapt to hypoxia by utilizing physiological adaptation pathways that promote a switch from oxidative to glycolytic metabolism. This promotes the conversion of glucose into lactate while limiting its transformation into acetyl coenzyme A (acetyl-CoA). The uptake of glucose and the glycolytic flux are increased under hypoxic conditions, mostly owing to the upregulation of genes encoding glucose transporters and glycolytic enzymes, a process that depends on hypoxia-inducible factor 1 (HIF-1). The reduced delivery of acetyl-CoA to the tricarboxylic acid cycle leads to a switch from glucose to glutamine as the major substrate for fatty acid synthesis in hypoxic cells. In addition, hypoxia induces (1) the HIF-1-dependent expression of BCL2/adenovirus E1B 19-kDa interacting protein 3 (BNIP3) and BNIP3-like (BNIP3L), which trigger mitochondrial autophagy, thereby decreasing the oxidative metabolism of both fatty acids and glucose, and (2) the expression of the sodium-hydrogen exchanger NHE1, which maintains an alkaline intracellular pH. Here, we present a compendium of methods to study hypoxia-induced metabolic alterations.

Chuang WY, Ströbel P, Bohlender-Willke AL, et al.
Late-onset myasthenia gravis - CTLA4(low) genotype association and low-for-age thymic output of naïve T cells.
J Autoimmun. 2014; 52:122-9 [PubMed] Related Publications
Late-onset myasthenia gravis (LOMG) has become the largest MG subgroup, but the underlying pathogenetic mechanisms remain mysterious. Among the few etiological clues are the almost unique serologic parallels between LOMG and thymoma-associated MG (TAMG), notably autoantibodies against acetylcholine receptors, titin, ryanodine receptor, type I interferons or IL-12. This is why we checked LOMG patients for two further peculiar features of TAMG - its associations with the CTLA4(high/gain-of-function) +49A/A genotype and with increased thymic export of naïve T cells into the blood, possibly after defective negative selection in AIRE-deficient thymomas. We analyzed genomic DNA from 116 Caucasian LOMG patients for CTLA4 alleles by PCR/restriction fragment length polymorphism, and blood mononuclear cells for recent thymic emigrants by quantitative PCR for T cell receptor excision circles. In sharp contrast with TAMG, we now find that: i) CTLA4(low) +49G(+) genotypes were more frequent (p = 0.0029) among the 69 LOMG patients with age at onset ≥60 years compared with 172 healthy controls; ii) thymic export of naïve T cells from the non-neoplastic thymuses of 36 LOMG patients was lower (p = 0.0058) at diagnosis than in 77 age-matched controls. These new findings are important because they suggest distinct initiating mechanisms in TAMG and LOMG and hint at aberrant immuno-regulation in the periphery in LOMG. We therefore propose alternate defects in central thymic or peripheral tolerance induction in TAMG and LOMG converging on similar final outcomes. In addition, our data support a 60-year-threshold for onset of 'true LOMG' and an LOMG/early-onset MG overlapping group of patients between 40 and 60.

Pereira-Caro G, Mateos R, Traka MH, et al.
Hydroxytyrosyl ethyl ether exhibits stronger intestinal anticarcinogenic potency and effects on transcript profiles compared to hydroxytyrosol.
Food Chem. 2013; 138(2-3):1172-82 [PubMed] Related Publications
The anticarcinogenic activity of hydroxytyrosyl ethyl ether (HTy-Et) compared to its precursor hydroxytyrosol (HTy) has been studied in human Caco-2 colon adenocarcinoma cells. 451 and 977 genes were differentially expressed in Caco-2 cells exposed to HTy or HTy-Et for 24h, respectively, compared with untreated cells (P<0.005; FDR=0), using Affymetrix microarrays. Results showed that both HTy and HTy-Et inhibited cell proliferation and arrested the cell cycle by up-regulating p21 and CCNG2 and down-regulating CCNB1 protein expression. HTy and HTy-Et also altered the transcription of specific genes involved in apoptosis, as suggested by the up-regulation of BNIP3, BNIP3L, PDCD4 and ATF3 and the activation of caspase-3. Moreover, these polyphenols up-regulated xenobiotic metabolizing enzymes UGT1A10 and CYP1A1, enhancing carcinogen detoxification. In conclusion, these results highlight that HTy and its derivative HTy-Et modulate molecular mechanisms involved in colon cancer, with HTy-Et being more effective than HTy.

Yang X, Zhong X, Tanyi JL, et al.
mir-30d Regulates multiple genes in the autophagy pathway and impairs autophagy process in human cancer cells.
Biochem Biophys Res Commun. 2013; 431(3):617-22 [PubMed] Free Access to Full Article Related Publications
In human epithelial cancers, the microRNA (miRNA) mir-30d is amplified with high frequency and serves as a critical oncomir by regulating metastasis, apoptosis, proliferation, and differentiation. Autophagy, a degradation pathway for long-lived protein and organelles, regulates the survival and death of many cell types. Increasing evidence suggests that autophagy plays an important function in epithelial tumor initiation and progression. Using a combined bioinformatics approach, gene set enrichment analysis, and miRNA target prediction, we found that mir-30d might regulate multiple genes in the autophagy pathway including BECN1, BNIP3L, ATG12, ATG5, and ATG2. Our further functional experiments demonstrated that the expression of these core proteins in the autophagy pathway was directly suppressed by mir-30d in cancer cells. Finally, we showed that mir-30d regulated the autophagy process by inhibiting autophagosome formation and LC3B-I conversion to LC3B-II. Taken together, our results provide evidence that the oncomir mir-30d impairs the autophagy process by targeting multiple genes in the autophagy pathway. This result will contribute to understanding the molecular mechanism of mir-30d in tumorigenesis and developing novel cancer therapy strategy.

Lu Y, Wang L, He M, et al.
Nix protein positively regulates NF-κB activation in gliomas.
PLoS One. 2012; 7(9):e44559 [PubMed] Free Access to Full Article Related Publications
Previous reports indicate that the NIX/BNIP3L gene acts as a pro-apoptotic factor by interacting with BCL2 and BCL-XL, playing an important role in hypoxia-dependent cell death and acting as a tumor suppressor. However, many studies also showed that NIX is linked to a protective role and cell survival in cancer cells. Nuclear factor-κB (NF-κB) can attenuate apoptosis in human cancers in response to chemotherapeutic agents and ionizing radiation. We observed an absence of i-κBα (NF-κB activation inhibitor) expression, but a greater expression of Nix and p-NF-κB proteins in the Nix-wt U251 cells, which was not observed in the Nix-kn cells under hypoxic conditions. Using electrophoretic mobility shift assay (EMSA) and luciferase detection, the activation of NF-κB was detected only in the Nix-wt U251 cells with hypoxia. These data imply that Nix protein might play a role in the positive regulation of the NF-κB pathway. Moreover, 46 cases of glioma also showed high levels of Nix protein expression, which was always accompanied by high p-NF-κB expression. Patients with Nix (+) showed less tissue apoptosis behavior in glioblastoma (GBM), unlike that observed in the Nix-negative patients (-). The same apoptotic tendency was also identified in anaplastic astrocytoma (AA) groups, but not in astrocytoma (AS). On analyzing the Kaplan-Meier curve, better tumor-free survival was observed only in cases of astrocytoma, and not in AA and GBM. Thus, our study indicates that Nix protein might have multiple functions in regulating glioma behaviors. In the low-grade gliomas (astrocytoma) with low expression of NF-κB, the cell death-inducing function that occurs through a Bax mechanism might predominate and act as a tumor suppressor. While in the malignant gliomas (AA and GBM), with higher expression of the NIX gene and with activity of the NF-κB pathway, the oncogene function of Nix was predominant.

Jin X, Wu XX, Jin C, et al.
Delineation of apoptotic genes for synergistic apoptosis of lexatumumab and anthracyclines in human renal cell carcinoma cells by polymerase chain reaction array.
Anticancer Drugs. 2012; 23(4):445-54 [PubMed] Related Publications
Lexatumumab, a human agonistic monoclonal antibody against tumor necrosis factor (TNF)-related apoptosis-inducing ligand receptor-2 (TRAIL-R2), is a promising molecular-targeted therapeutic agent. Our past study indicated that low concentrations of doxorubicin sensitized renal cell carcinoma (RCC) cells to lexatumumab-mediated apoptosis. The present study was designed to examine the cellular and molecular effects of lexatumumab and anthracyclines in RCC cells. The treatment of human RCC cells with lexatumumab in combination with anthracyclines, epirubicin, and pirarubicin had a synergistic cytotoxicity. A marked synergistic apoptosis was induced by lexatumumab in combination with epirubicin or pirarubicin. Epirubicin and pirarubicin significantly increased the TRAIL-R2 expression at both the mRNA and the protein levels. The combination-induced cytotoxicity was significantly suppressed by the human recombinant DR5:Fc chimeric protein. To further explore the molecular mechanisms in this synergistic cytotoxicity with lexatumumab and anthracyclines, the changes in 84 apoptosis-related genes were evaluated by a quantitative polymerase chain reaction (PCR) array. Among these genes, 18 (CD40LG, FASLG, LTA, TNSF7, FAS, BAG3, BAK1, BAX, BID, BIK, BCL10, caspase-1, caspase-5, caspase-6, caspase-10, TNF receptor-associated factor 1, PYCARD, and CIDEA) were significantly upregulated and eight (TNF receptor-associated factor 4, TNFRSF11B, TNF, BCL2, BCL2L1, BNIP3L, caspase-9, and DAPK1) were downregulated at mRNA levels in RCC cells cotreated with lexatumumab and epirubicin. Furthermore, the upregulation of mRNA levels of PYCARD and CIDEA was confirmed using real-time reverse transcriptase-PCR analysis. The present study demonstrates that anthracylines sensitize RCC cells to lexatumumab-mediated apoptosis by inducing TRAIL-R2 expression, and the utility of PCR array to elucidate the mechanism of synergistic apoptosis.

Knutson AK, Welsh J, Taylor T, et al.
Comparative effects of histone deacetylase inhibitors on p53 target gene expression, cell cycle and apoptosis in MCF-7 breast cancer cells.
Oncol Rep. 2012; 27(3):849-53 [PubMed] Related Publications
Histone deacetylase inhibitors are currently being evaluated for their therapeutic potential and have shown considerable promise as adjuvant therapies for a number of cancers. This study compared the effects of 2 hydroxamic acid based inhibitors, CG-1521 and SAHA, on gene expression, cell cycle and cell death in MCF-7 human breast cancer cells. Both compounds show a dose- and time-dependent effect on cell number (evaluated using crystal violet), however CG-1521 exerts its effects significantly earlier than SAHA, and CG-1521 induces apoptosis (assessed by Apo-BrdU staining and flow cytometry) more rapidly than SAHA. qPCR of cell cycle regulatory and apoptotic genes shows that CG-1521 and SAHA modulate similar cohorts of p53-responsive genes, however, the levels of induction and the timing of the induction differs significantly between the 2 inhibitors. In particular SAHA downregulates cell cycle-associated genes that modulate the G1/S transition (including cyclin D1 and cdc25a) and the G2/M transition [cyclin B1, Plk1, Stk6 (serine-threonine kinase 6, Aurora kinase A) and Kntc2] more significantly than CG-1521. In contrast, CG-1521 significantly induces the expression of several p53 target genes associated with apoptosis including Bnip3/Bnip3L, p21/p21B and Gdf15. The differential levels of gene induction provide molecular evidence of both cell cycle arrest and apoptosis, and suggest a molecular mechanism that explains the difference in the biological effects of the 2 histone deacetylase inhibitors.

Whitaker-Menezes D, Martinez-Outschoorn UE, Flomenberg N, et al.
Hyperactivation of oxidative mitochondrial metabolism in epithelial cancer cells in situ: visualizing the therapeutic effects of metformin in tumor tissue.
Cell Cycle. 2011; 10(23):4047-64 [PubMed] Free Access to Full Article Related Publications
We have recently proposed a new mechanism for explaining energy transfer in cancer metabolism. In this scenario, cancer cells behave as metabolic parasites, by extracting nutrients from normal host cells, such as fibroblasts, via the secretion of hydrogen peroxide as the initial trigger. Oxidative stress in the tumor microenvironment then leads to autophagy-driven catabolism, mitochondrial dys-function, and aerobic glycolysis. This, in turn, produces high-energy nutrients (such as L-lactate, ketones, and glutamine) that drive the anabolic growth of tumor cells, via oxidative mitochondrial metabolism. A logical prediction of this new "parasitic" cancer model is that tumor-associated fibroblasts should show evidence of mitochondrial dys-function (mitophagy and aerobic glycolysis). In contrast, epithelial cancer cells should increase their oxidative mitochondrial capacity. To further test this hypothesis, here we subjected frozen sections from human breast tumors to a staining procedure that only detects functional mitochondria. This method detects the in situ enzymatic activity of cytochrome C oxidase (COX), also known as Complex IV. Remarkably, cancer cells show an over-abundance of COX activity, while adjacent stromal cells remain essentially negative. Adjacent normal ductal epithelial cells also show little or no COX activity, relative to epithelial cancer cells. Thus, oxidative mitochondrial activity is selectively amplified in cancer cells. Although COX activity staining has never been applied to cancer tissues, it could now be used routinely to distinguish cancer cells from normal cells, and to establish negative margins during cancer surgery. Similar results were obtained with NADH activity staining, which measures Complex I activity, and succinate dehydrogenase (SDH) activity staining, which measures Complex II activity. COX and NADH activities were blocked by electron transport inhibitors, such as Metformin. This has mechanistic and clinical implications for using Metformin as an anti-cancer drug, both for cancer therapy and chemo-prevention. We also immuno-stained human breast cancers for a series of well-established protein biomarkers of metabolism. More specifically, we now show that cancer-associated fibroblasts over-express markers of autophagy (cathepsin B), mitophagy (BNIP3L), and aerobic glycolysis (MCT4). Conversely, epithelial cancer cells show the over-expression of a mitochondrial membrane marker (TOMM20), as well as key components of Complex IV (MT-CO1) and Complex II (SDH-B). We also validated our observations using a bioinformatics approach with data from > 2,000 breast cancer patients, which showed the transcriptional upregulation of mitochondrial oxidative phosphorylation (OXPHOS) in human breast tumors (p < 10(-20)), and a specific association with metastasis. Therefore, upregulation of OXPHOS in epithelial tumor cells is a common feature of human breast cancers. In summary, our data provide the first functional in vivo evidence that epithelial cancer cells perform enhanced mitochondrial oxidative phosphorylation, allowing them to produce high amounts of ATP. Thus, we believe that mitochondria are both the "powerhouse" and "Achilles' heel" of cancer cells.

Munksgaard Persson M, Johansson ME, Monsef N, et al.
HIF-2α expression is suppressed in SCLC cells, which survive in moderate and severe hypoxia when HIF-1α is repressed.
Am J Pathol. 2012; 180(2):494-504 [PubMed] Related Publications
Small cell lung carcinoma (SCLC) is extremely aggressive and frequently metastasizes widely in its early stage. Because tumor hypoxia is related to aggressive tumor behavior and the hypoxic adaptation of SCLC is poorly documented, we stained SCLC tumors arranged in a tissue microarray for hypoxia-inducible factor (HIF)-1α and HIF-2α proteins. We found an overall lack of HIF-2α protein expression, which was confirmed in large tumor sections. HIF-1α protein was strongly expressed in most tumors, frequently adjacent to necrotic regions. In concordance, cultured SCLC but not non-small cell lung carcinoma cells showed no or extremely low levels of HIF-2α mRNA and no HIF-2α protein at hypoxia. HIF-1α was stabilized after 4 hours at hypoxia, and its accumulation increased up to 96 hours. SCLC cells survived well and showed net proliferation and low cell death in modest (1% oxygen) and severe (0.1% oxygen) hypoxia. HIF-1α repression virtually did not influence cell death or viability despite reduced levels of hypoxia-inducible genes, such as BNIP3 and BNIP3L. At 1% oxygen no increased autophagy (LC3B-II activation) or NF-κB signaling were detected, whereas the unfolded protein response was activated at severe hypoxia. Our data indicate that HIFs are not exclusively required for SCLC cell survival at modest or severe hypoxia and that additional, yet uncharacterized, hypoxia-driven adaptation pathways may become activated.

Cheng I, Levin AM, Tai YC, et al.
Copy number alterations in prostate tumors and disease aggressiveness.
Genes Chromosomes Cancer. 2012; 51(1):66-76 [PubMed] Free Access to Full Article Related Publications
Detecting genomic alterations that result in more aggressive prostate cancer may improve clinical treatment and our understanding of the biology underlying this common but complex disease. To this end, we undertook a genome-wide copy number alterations (CNAs) study of clinicopathological characteristics of 62 prostate tumors using the Illumina 1M single nucleotide polymorphism array. The highest overall frequencies of CNAs were on chromosomes 8q (gains), 8p (loss and copy-neutral), and 6q (copy-loss). Combined loss and copy-neutral events were associated with increasing disease grade (P = 0.03), stage (P = 0.01), and diagnostic prostate specific antigen (PSA) (P = 0.01). Further evaluation of CNAs using gene ontology identified pathways involved with disease aggressiveness. The "regulation of apoptosis" pathway was associated with stage of disease (P = 0.004), while the "reproductive cellular process" pathway was associated with diagnostic PSA (P = 0.00038). Specific genes within these pathways exhibited strong associations with clinical characteristics; for example, in the apoptosis pathway BNIP3L was associated with increasing prostate tumor stage (P = 0.007). These findings confirm known regions of CNAs in prostate cancer and localize additional regions and possible genes (e.g., BNIP3L, WWOX, and GATM) that may help to clarify the genetic basis of prostate cancer aggressiveness.

Foulks JM, Parnell KM, Nix RN, et al.
Epigenetic drug discovery: targeting DNA methyltransferases.
J Biomol Screen. 2012; 17(1):2-17 [PubMed] Related Publications
Epigenetic modification of DNA leads to changes in gene expression. DNA methyltransferases (DNMTs) comprise a family of nuclear enzymes that catalyze the methylation of CpG dinucleotides, resulting in an epigenetic methylome distinguished between normal cells and those in disease states such as cancer. Disrupting gene expression patterns through promoter methylation has been implicated in many malignancies and supports DNMTs as attractive therapeutic targets. This review focuses on the rationale of targeting DNMTs in cancer, the historical approach to DNMT inhibition, and current marketed hypomethylating therapeutics azacytidine and decitabine. In addition, we address novel DNMT inhibitory agents emerging in development, including CP-4200 and SGI-110, analogs of azacytidine and decitabine, respectively; the oligonucleotides MG98 and miR29a; and a number of reversible inhibitors, some of which appear to be selective against particular DNMT isoforms. Finally, we discuss future opportunities and challenges for next-generation therapeutics.

Pérez-Perarnau A, Coll-Mulet L, Rubio-Patiño C, et al.
Analysis of apoptosis regulatory genes altered by histone deacetylase inhibitors in chronic lymphocytic leukemia cells.
Epigenetics. 2011; 6(10):1228-35 [PubMed] Related Publications
Histone deacetylases (HDACs) play a key role in the regulation of acetylation status not only of histones but also of many other non-histone proteins involved in cell cycle regulation, differentiation or apoptosis. Therefore, histone deacetylase inhibitors (HDACi) have emerged as promising anticancer agents. Herein, we report the characterization of apoptosis in B-cell chronic lymphocytic leukemia (CLL) induced by two HDACi, Kendine 92 and SAHA. Both inhibitors induce dose-, time- and caspase-dependent apoptosis through the mitochondrial pathway. Interestingly, Kendine 92 and SAHA show a selective cytotoxicity for B lymphocytes and induce apoptosis in CLL cells with mutated or deleted TP53 as effectively as in tumor cells harboring wild-type TP53. The pattern of apoptosis-related gene and protein expression profile has been characterized. It has shown to be irrespective of TP53 status and highly similar between SAHA and Kendine 92 exposure. The balance between the increased BAD, BNIP3L, BNIP3, BIM, PUMA and AIF mRNA expression levels, and decreased expression of BCL-W, BCL-2, BFL-1, XIAP and FLIP indicates global changes in the apoptosis mRNA expression profile consistent with the apoptotic outcome. Protein expression analysis shows increased levels of NOXA, BIM and PUMA proteins upon Kendine 92 and SAHA treatment. Our results highlight the capability of these molecules to induce apoptosis not only in a selective manner but also in those cells frequently resistant to standard treatments. Thus, Kendine 92 is a novel HDACi with anticancer efficacy for non-proliferating CLL cells.

Pen A, Durocher Y, Slinn J, et al.
Insulin-like growth factor binding protein 7 exhibits tumor suppressive and vessel stabilization properties in U87MG and T98G glioblastoma cell lines.
Cancer Biol Ther. 2011; 12(7):634-46 [PubMed] Related Publications
Insulin-like growth factor binding protein 7 (IGFBP7) is downregulated in several solid cancers. IGFBP7 has been proposed to act as a tumor suppressor gene through mechanisms involving senescence and apoptotic pathways. The tumor suppressor effect of IGFBP7 in glioblastoma multiforme (GBM) was examined in this study using two human GBM cell lines, U87MG and T98G. Exogenously applied IGFBP7 (20 and 100 nM) significantly reduced U87MG (~70 and ~75%, respectively) and T98G (~37 and ~50%, respectively) cell growth in soft agar. IGFBP7 stimulated senescence-associated β-galactosidase in both U87MG and T98G cells without stimulating apoptosis (annexin V and propidium iodide staining, expression of SMARCB1 or BNIP3L and caspase cleavage) or affecting phosphorylation of p44/42 MAPK. The inhibitory effect of IGFBP7 on U87MG cell growth was further assessed in vivo using U87MG cells grafted on the chick chorioallantoic membrane. In this model, U87MG cells formed solid and highly vascularized tumors that were reduced in size (~40%) when treated with 500 nM IGFBP7 compared with control tumors. Vessels in IGFBP7-treated tumors were clustered, unevenly distributed and associated with higher number of α-SMA positive cells compared with those in untreated tumors. IGFBP7 induced both aortic smooth muscle cell (AoSMC) chemoattraction and endothelial cell (EC) transdifferentiation into a SM-like cell phenotype. U87MG conditioned media-induced IGFBP7 expression in ECs was significantly inhibited by the cross-talk/interaction with SMCs. This study indicates that IGFBP7 suppresses U87MG tumor cell growth, induces cell senescence and participates in tumor vessel stabilization by promoting SMC/pericyte recruitment and differentiation.

Brown J, Bothma H, Veale R, Willem P
Genomic imbalances in esophageal carcinoma cell lines involve Wnt pathway genes.
World J Gastroenterol. 2011; 17(24):2909-23 [PubMed] Free Access to Full Article Related Publications
AIM: To identify molecular markers shared across South African esophageal squamous cell carcinoma (ESCC) cell lines using cytogenetics, fluorescence in situ hybridization (FISH) and single nucleotide polymorphism (SNP) array copy number analysis.
METHODS: We used conventional cytogenetics, FISH, and multicolor FISH to characterize the chromosomal rearrangements of five ESCC cell lines established in South Africa. The whole genome copy number profile was established from 250K SNP arrays, and data was analyzed with the CNAT 4.0 and GISTIC software.
RESULTS: We detected common translocation breakpoints involving chromosomes 1p11-12 and 3p11.2, the latter correlated with the deletion, or interruption of the EPHA3 gene. The most significant amplifications involved the following chromosomal regions and genes: 11q13.3 (CCND1, FGF3, FGF4, FGF19, MYEOV), 8q24.21(C-MYC, FAM84B), 11q22.1-q22.3 (BIRC2, BIRC3), 5p15.2 (CTNND2), 3q11.2-q12.2 (MINA) and 18p11.32 (TYMS, YES1). The significant deletions included 1p31.2-p31.1 (CTH, GADD45α, DIRAS3), 2q22.1 (LRP1B), 3p12.1-p14.2 (FHIT), 4q22.1-q32.1 (CASP6, SMAD1), 8p23.2-q11.1 (BNIP3L) and 18q21.1-q21.2 (SMAD4, DCC). The 3p11.2 translocation breakpoint was shared across four cell lines, supporting a role for genes involved at this site, in particular, the EPHA3 gene which has previously been reported to be deleted in ESCC.
CONCLUSION: The finding that a significant number of genes that were amplified (FGF3, FGF4, FGF19, CCND1 and C-MYC) or deleted (SFRP2 gene) are involved in the Wnt and fibroblast growth factor signaling pathways, suggests that these pathways may be activated in these cell lines.

Moussay E, Kaoma T, Baginska J, et al.
The acquisition of resistance to TNFα in breast cancer cells is associated with constitutive activation of autophagy as revealed by a transcriptome analysis using a custom microarray.
Autophagy. 2011; 7(7):760-70 [PubMed] Related Publications
While the autophagic process is mainly regulated at the post-translational level, a growing body of evidence suggests that autophagy might also be regulated at the transcriptional level. The identification of transcription factors involved in the regulation of autophagy genes has provided compelling evidence for such regulation. In this context, a powerful high throughput analysis tool to simultaneously monitor the expression level of autophagy genes is urgently needed. Here we describe setting up the first comprehensive human autophagy database (HADb, available at www.autophagy.lu) and the development of a companion Human Autophagy-dedicated cDNA Microarray which comprises 234 genes involved in or related to autophagy. The autophagy microarray tool used on breast adenocarcinoma MCF-7 cell line allowed the identification of 47 differentially expressed autophagy genes associated with the acquisition of resistance to the cytotoxic effect of TNFα. The autophagy-core machinery genes DRAM (Damage-Regulated Autophagy Modulator), BNIP3L (BCL2/adenovirus E1B 19 kDa interacting protein 3-like), BECN1 (Beclin 1), GABARAP (Gamma-AminoButyric Acid Receptor-Associated Protein) and UVRAG (UV radiation resistance associated gene) were found upregulated in TNF-resistant cells, suggesting a constitutive activation of the autophagy machinery in these cells. More interestingly, we identified NPC1 as the most upregulated genes in TNF-resistant compared to TNF-sensitive MCF-7 cells, suggesting a relation between the intracellular transport of cholesterol, the regulation of autophagy and NPC1 expression in TNF-resistant tumor cells. In conclusion, we describe here new tools that may help investigating autophagy gene regulation in various cellular models and diseases.

Marx A, Willcox N, Leite MI, et al.
Thymoma and paraneoplastic myasthenia gravis.
Autoimmunity. 2010; 43(5-6):413-27 [PubMed] Related Publications
Paraneoplastic autoimmune diseases associate occasionally with small cell lung cancers and gynecologic tumors. However, myasthenia gravis (MG) occurs in at least 30% of all patients with thymomas (usually present at MG diagnosis). These epithelial neoplasms almost always have numerous admixed maturing polyclonal T cells (thymocytes). This thymopoiesis-and export of mature CD4(+)T cells-particularly associates with MG, though there are rare/puzzling exceptions in apparently pure epithelial WHO type A thymomas. Other features potentially leading to inefficient self-tolerance induction include defective epithelial expression of the autoimmune regulator (AIRE) gene and/or of major histocompatibility complex class II molecules in thymomas, absence of myoid cells, failure to generate FOXP3(+) regulatory T cells, and genetic polymorphisms affecting T-cell signaling. However, the strong focus on MG/neuromuscular targets remains unexplained and suggests some biased autoantigen expression, T-cell selection, or autoimmunization within thymomas. There must be further clues in the intriguing serological and cellular parallels in some patients with late-onset MG but without thymomas-and in others with AIRE mutations-and in the contrasts with early-onset MG, as discussed here.

Chiche J, Rouleau M, Gounon P, et al.
Hypoxic enlarged mitochondria protect cancer cells from apoptotic stimuli.
J Cell Physiol. 2010; 222(3):648-57 [PubMed] Related Publications
It is well established that cells exposed to the limiting oxygen microenvironment (hypoxia) of tumors acquire resistance to chemotherapy, through mechanisms not fully understood. We noted that a large number of cell lines showed protection from apoptotic stimuli, staurosporine, or etoposide, when exposed to long-term hypoxia (72 h). In addition, these cells had unusual enlarged mitochondria that were induced in a HIF-1-dependent manner. Enlarged mitochondria were functional as they conserved their transmembrane potential and ATP production. Here we reveal that mitochondria of hypoxia-induced chemotherapy-resistant cells undergo a HIF-1-dependent and mitofusin-1-mediated change in morphology from a tubular network to an enlarged phenotype. An imbalance in mitochondrial fusion/fission occurs since silencing of not only the mitochondrial fusion protein mitofusin 1 but also BNIP3 and BNIP3L, two mitochondrial HIF-targeted genes, reestablished a tubular morphology. Hypoxic cells were insensitive to staurosporine- and etoposide-induced cell death, but the silencing of mitofusin, BNIP3, and BNIP3L restored sensitivity. Our results demonstrate that some cancer cells have developed yet another way to evade apoptosis in hypoxia, by inducing mitochondrial fusion and targeting BNIP3 and BNIP3L to mitochondrial membranes, thereby giving these cells a selective growth advantage.

Chuang WY, Ströbel P, Belharazem D, et al.
The PTPN22gain-of-function+1858T(+) genotypes correlate with low IL-2 expression in thymomas and predispose to myasthenia gravis.
Genes Immun. 2009; 10(8):667-72 [PubMed] Related Publications
Protein tyrosine phosphatase, non-receptor type 22 (PTPN22) inhibits T-cell activation and interleukin-2 (IL-2) production. The PTPN22(gain-of-function)+1858T(+) genotypes predispose to multiple autoimmune diseases, including early-onset (non-thymomatous) myasthenia gravis (MG). The disease association and the requirement of IL-2/IL-2 receptor signaling for intrathymic, negative T-cell selection have suggested that these genotypes may weaken T-cell receptor (TCR) signaling and impair the deletion of autoreactive T cells. Evidence for this hypothesis is missing. Thymoma-associated MG, which depends on intratumorous generation and export of mature autoreactive CD4(+) T cells, is a model of autoimmunity because of central tolerance failure. Here, we analyzed the PTPN22 +1858C/T single nucleotide polymorphism in 426 German Caucasian individuals, including 125 thymoma patients (79 with MG), and investigated intratumorous IL-2 expression levels. Unlike two previous studies on French and Swedish patients, we found strong association of PTPN22 +1858T(+) genotypes not only with early-onset MG (P=0.00034) but also with thymoma-associated MG (P=0.0028). IL-2 expression in thymomas with PTPN22 +1858T(+) genotypes (P=0.028) was lower, implying weaker TCR signaling. We conclude that the PTPN22(gain-of-function) variant biases towards MG in a subgroup of thymoma patients possibly by impeding central tolerance induction.

Lomonosova E, Chinnadurai G
BH3-only proteins in apoptosis and beyond: an overview.
Oncogene. 2008; 27 Suppl 1:S2-19 [PubMed] Free Access to Full Article Related Publications
BH3-only BCL-2 family proteins are effectors of canonical mitochondrial apoptosis. They discharge their pro-apoptotic functions through BH1-3 pro-apoptotic proteins such as BAX and BAK, while their activity is suppressed by BH1-4 anti-apoptotic BCL-2 family members. The precise mechanism by which BH3-only proteins mediate apoptosis remains unresolved. The existing data are consistent with three mutually non-exclusive models (1) displacement of BH1-3 proteins from complexes with BH1-4 proteins; (2) direct interaction with and conformational activation of BH1-3 proteins; and (3) membrane insertion and membrane remodeling. The BH3-only proteins appear to play critical roles in restraining cancer and inflammatory diseases such as rheumatoid arthritis. Molecules that mimic the effect of BH3-only proteins are being used in treatments against these diseases. The cell death activity of a subclass of BH3-only members (BNIP3 and BNIP3L) is linked to cardiomyocyte loss during heart failure. In addition to their established role in apoptosis, several BH3-only members also regulate diverse cellular functions in cell-cycle regulation, DNA repair and metabolism. Several members are implicated in the induction of autophagy and autophagic cell death, possibly through unleashing of the BH3-only autophagic effector Beclin 1 from complexes with BCL-2/BCL-xL. The Chapters included in the current Oncogene Review issues provide in-depth discussions on various aspects of major BH3-only proteins.

Chinnadurai G, Vijayalingam S, Gibson SB
BNIP3 subfamily BH3-only proteins: mitochondrial stress sensors in normal and pathological functions.
Oncogene. 2008; 27 Suppl 1:S114-27 [PubMed] Free Access to Full Article Related Publications
The BNIP3 subfamily of BH3-only proteins consists of BNIP3 and BNIP3-like (BNIP3L) proteins. These proteins form stable homodimerization complexes that localize to the outer membrane of the mitochondria after cellular stress. This promotes either apoptotic or non-apoptotic cell death such as autophagic cell death. Although the mammalian cells contain both members of this subfamily, the genome of Caenorhabditis elegans codes for a single BNIP3 ortholog, ceBNIP3, which shares homology in the transmembrane (TM) domain and in a conserved region close to the BH3 domain of mammalian BNIP3 protein. The cell death activities of BNIP3 and BNIP3L are determined by either the BH3 domain or the C-terminal TM domain. The TM domain of BNIP3 is unique, as it is capable of autonomous stable dimerization and contributes to mitochondrial localization of BNIP3. In knockout mouse models, BNIP3L was shown to be essential for normal erythrocyte differentiation and hematopoietic homeostasis, whereas BNIP3 plays a role in cellular responses to ischemia/reperfusion injury in the heart. Both BNIP3 and BNIP3L play a role in cellular responses to stress. Under hypoxia, both BNIP3 and BNIP3L expression levels are elevated and contribute to hypoxia-induced cell death. In addition, these proteins play critical roles in disease states. In heart disease, both BNIP3 and BNIP3L play a critical role in cardiomyocyte cell death following ischemic and non-ischemic injuries. In cancer, expression of BNIP3 and BNIP3L is downregulated by promoter hypermethylation or by homozygous deletion of the gene locus in certain cancers, whereas their expression was increased in other cancers. In addition, BNIP3 expression has been correlated with poor prognosis in some cancers. The results reviewed here suggest that BNIP3 and BNIP3L may be novel therapeutic targets for intervention because of their pathological roles in regulating cell death in disease states.

Cellai C, Laurenzana A, Bianchi E, et al.
Mechanistic insight into WEB-2170-induced apoptosis in human acute myelogenous leukemia cells: the crucial role of PTEN.
Exp Hematol. 2009; 37(10):1176-1185.e21 [PubMed] Related Publications
OBJECTIVE: This study aimed to investigate the mechanisms of action of WEB-2170, an inverse agonist of platelet-activating factor receptor, capable of inducing apoptosis in human acute myelogenous leukemia (AML) cells.
MATERIAL AND METHODS: Gene expression profiling followed by cytofluorimetric, morphologic, and biologic analyses were used to monitor WEB-2170 effects in AML cell lines (ie, NB4, KG1, NB4-MR4, THP1, and U937) and blasts from patients with different AML (M0-M5) subtypes. PTEN silencing with small interfering RNA was also performed.
RESULTS: We have demonstrated that drug-mediated cytostasis/apoptosis in NB4 cells is characterized by upregulation of cyclin G2, p21/WAF1, NIX, TNF-alpha, and PTEN expression, and downregulation of cyclin D2 and BCL2 expression. We observed an increase in PTEN protein accompanied by a decrease in phospho-extracellular signal-regulated kinase 2 (ERK2) and phospho-AKT, and by forkhead box O3a (FOXO3a) cytoplasmic-nuclear translocation; the mitochondrial cytochrome C release and PARP cleavage marked the late apoptotic steps. We have found that WEB-2170 triggered apoptosis in NB4, KG1, and NB4-MR4 cells where PTEN was expressed, but not in THP1 and U937 cells where PTEN was absent. Finally, we show that PTEN silencing in NB4 cells by PTEN-specific small interfering RNA resulted in a significant reduction of drug-induced apoptosis.
CONCLUSION: We demonstrated that WEB-2170 is a powerful antileukemic agent with interesting translational opportunities to treat AML and described mechanisms of drug-induced intrinsic and extrinsic apoptosis both in AML cell lines and blasts from AML patients by addressing PTEN as the master regulator of the whole process.

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