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1.
Lipids Health Dis ; 23(1): 59, 2024 Feb 27.
Article in English | MEDLINE | ID: mdl-38414008

ABSTRACT

Cancer cells need constant supplies of lipids to survive and grow. Lipid dependence has been observed in various types of cancer, including high-grade serous ovarian carcinomas (HGSOC), which is a lethal form of gynecological malignancy. ANGPTL3, PCSK9, and Apo CIII are pivotal lipid-modulating factors, and therapeutic antibodies have been developed against each one (Evinacumab, Evolocumab and Volanesorsen, respectively). The roles -if any- of ANGPTL3, PCSK9, and Apo CIII in HGSOC are unclear. Moreover, levels of these lipid-modulating factors have never been reported before in HGSOC. In this study, circulating levels of ANGPTL3, PCSK9, and Apo CIII, along with lipid profiles, are examined to verify whether one or many of these lipid-regulating factors are associated with HGSOC. Methods ELISA kits were used to measure ANGPTL3, PCSK9 and Apo CIII levels in plasma samples from 31 women with HGSOC and 40 women with benign ovarian lesions (BOL) before treatment and surgery. A Roche Modular analytical platform measured lipid panels, Apo B and Lp(a) levels.Results ANGPTL3 levels were higher in women with HGSOC (84 ng/mL, SD: 29 ng/mL, n = 31) than in women with BOL (67 ng/mL, SD: 31 ng/mL, n = 40; HGSOC vs. BOL P = 0.019). Associations between the lipid panel and ANGPTL3, and the inverse relationship between HDL-cholesterol and triglycerides, were present in women with BOL but not with HGSOC. PCSK9 and Apo CIII were not associated with HGSOC.Conclusions In this cohort of 71 women, ANGPTL3 levels were increased in HGSOC patients. The presence of HGSOC disrupted the classic inverse relationship between HDL and triglycerides, as well as the association between the lipid panel and ANGPTL3. These associations were only maintained in cancer-free women. Given the availability of Evinacumab, a therapeutic antibody against ANGPTL3, the current finding prompts an assessment of whether ANGPTL3 inhibition has therapeutic potential in HGSOC.


Subject(s)
Carcinoma , Ovarian Cysts , Ovarian Neoplasms , Humans , Female , Proprotein Convertase 9 , Angiopoietin-like Proteins/genetics , Angiopoietin-Like Protein 3 , Ovarian Neoplasms/drug therapy , Triglycerides , Angiopoietins/genetics
2.
NAR Cancer ; 4(4): zcac034, 2022 Dec.
Article in English | MEDLINE | ID: mdl-36348939

ABSTRACT

Emerging evidence associates translation factors and regulators to tumorigenesis. However, our understanding of translational changes in cancer resistance is still limited. Here, we generated an enzalutamide-resistant prostate cancer (PCa) model, which recapitulated key features of clinical enzalutamide-resistant PCa. Using this model and poly(ribo)some profiling, we investigated global translation changes that occur during acquisition of PCa resistance. We found that enzalutamide-resistant cells exhibit an overall decrease in mRNA translation with a specific deregulation in the abundance of proteins involved in mitochondrial processes and in translational regulation. However, several mRNAs escape this translational downregulation and are nonetheless bound to heavy polysomes in enzalutamide-resistant cells suggesting active translation. Moreover, expressing these corresponding genes in enzalutamide-sensitive cells promotes resistance to enzalutamide treatment. We also found increased association of long non-coding RNAs (lncRNAs) with heavy polysomes in enzalutamide-resistant cells, suggesting that some lncRNAs are actively translated during enzalutamide resistance. Consistent with these findings, expressing the predicted coding sequences of known lncRNAs JPX, CRNDE and LINC00467 in enzalutamide-sensitive cells drove resistance to enzalutamide. Taken together, this suggests that aberrant translation of specific mRNAs and lncRNAs is a strong indicator of PCa enzalutamide resistance, which points towards novel therapeutic avenues that may target enzalutamide-resistant PCa.

3.
BMC Cancer ; 22(1): 1049, 2022 Oct 06.
Article in English | MEDLINE | ID: mdl-36203122

ABSTRACT

BACKGROUND / SYNOPSIS: Cholesterol and lipids play an important role in sustaining tumor growth and metastasis in a large variety of cancers. ANGPTL3 and PCSK9 modify circulating cholesterol levels, thus availability of lipids to peripheral cells. Little is known on the role, if any, of circulating lipid-related factors such as PCSK9, ANGPTL3 and lipoprotein (a) in cancers. OBJECTIVE/PURPOSE: To compare circulating levels of PCSK9, ANGPTL3, and Lp(a) in women with stage III breast cancer versus women with premalignant or benign breast lesions. METHODS: Twenty-three plasma samples from women diagnosed with a stage III breast cancer (ductal, lobular or mixed) were matched for age with twenty-three plasma samples from women bearing premalignant (stage 0, n = 9) or benign (n = 14) breast lesions. The lipid profile (Apo B, total cholesterol, HDL cholesterol and triglycerides levels) and Lp(a) were measured on a Roche Modular analytical platform, whereas LDL levels were calculated with the Friedewald formula. ANGPTL3 and PCSK9 plasma levels were quantitated by ELISA. All statistical analyses were performed using SAS software version 9.4. RESULTS: PCSK9 levels were significantly higher in women with stage III breast cancer compared to age-matched counterparts presenting a benign lesion (95.9 ± 27.1 ng/mL vs. 78.5 ± 19.3 ng/mL, p < 0.05, n = 14). Moreover, PCSK9 levels positively correlated with breast disease severity (benign, stage 0, stage III) (Rho = 0.34, p < 0.05, n = 46). In contrast, ANGPTL3 and Lp(a) plasma levels did not display any association with breast disease status and lipids did not correlate with disease severity. CONCLUSION: In this small cohort of 46 women, PCSK9 levels tended to increase with the severity of the breast disease. Given that PCSK9 plays an important role in maintaining cholesterolemia, and a potential role in tumor evasion, present results warrant further investigation into a possible association between PCSK9 levels and breast cancer severity in larger cohorts of women.


Subject(s)
Breast Neoplasms , Proprotein Convertase 9 , Angiopoietin-Like Protein 3 , Angiopoietin-like Proteins , Apolipoproteins B , Cholesterol , Cholesterol, HDL , Female , Humans , Lipoprotein(a) , Triglycerides
4.
Eur Urol Open Sci ; 43: 35-44, 2022 Sep.
Article in English | MEDLINE | ID: mdl-36246841

ABSTRACT

Background: Men are three to four times more likely to be diagnosed with bladder cancer (BCa) than women, who often have more aggressive tumors. Intravesical bacillus Calmette-Guerin (BCG) for non-muscle-invasive bladder cancer (NMIBC) is one of the first immunotherapies, with use of immune checkpoint inhibitors for BCa immunotherapy expanding. Sex hormones, and notably androgens, might impact the outcome of these therapies. Objective: To understand immunological sex differences in BCa and investigate androgen receptor (AR) inhibition as a novel strategy to improve the response to BCa immunotherapy. Design setting and participants: Human NMIBC tumors were freshly collected following transurethral resection. In vivo studies used the subcutaneous MBT-2 BCa model in male and female C3H mice. The AR antagonist enzalutamide was given alone or in combination with anti-programmed cell death protein-1 (anti-PD-1) or intratumoral BCG + poly(I:C) treatments. Outcome measurements and statistical analysis: Tumor growth and survival were evaluated in vivo. Flow cytometry and RNA sequencing characterized the immune cells present in murine and human tumors. Descriptive comparisons were performed for MBT-2 tumors between sexes and with human NMIBC tumors. Results and limitations: The MBT-2 model shows multiple similarities to the immune composition of human NMIBC tumors and recapitulates previously observed human tumor immune cell sex differences. Enzalutamide in combination with either anti-PD-1 or BCG + poly(I:C) treatment in male mice synergized to improve response rates. Notably, the proportion of complete responses in male mice treated with the combination treatment resembles that observed in female mice with either immunotherapy alone. Limitations include the sample size for murine experiments. Conclusions: Our results suggest that combining AR antagonism with immunotherapy in male BCa patients may potentiate the antitumor immune response and increase response rates. The MBT-2 model appears relevant to investigate immunological BCa sex differences. Patient summary: Our studies suggest that combining antiandrogen treatments with BCa immunotherapy may improve response rates in men. We also demonstrate the utility of the MBT-2 mouse model to study sex differences in BCa.

5.
Am J Clin Exp Urol ; 10(2): 98-110, 2022.
Article in English | MEDLINE | ID: mdl-35528461

ABSTRACT

BACKGROUND: The role of androgens and other sex steroids is known to influence the prognosis and progression of prostate cancer through different disease states. While androgens are generally regarded as immunosuppressive and estrogens as inflammatory, the specific influence of sex steroids on the immune microenvironment of prostate tumors remains incompletely understood. MATERIAL AND METHODS: In this study, we evaluate the link between sex steroids and prostate cancer immune cells, particularly macrophages. Using in vitro and in vivo models, as well as ex vivo culture of patient prostate tissue, we evaluated the influence of androgen, estrogen, and progesterone on immune cells of the prostate microenvironment. RESULTS: In vitro, we observed sex steroids induced indirect changes on prostate cancer cell proliferation via THP-1 derived macrophages, but no clear changes were induced using human monocyte derived macrophages. Comparing immunohistochemistry for immunosuppressive macrophage marker CD163 with concomitant circulating sex steroids from the same patients, we observed a correlation with higher dehydroepiandrosterone (DHEA)-sulfate and estrone-sulfate levels associated with higher prostate CD163 expression. Similar relationships between DHEA and CD163 levels were observed in ex vivo cultured prostate biopsies. Finally, in a murine prostate cancer model of long-term sex steroids we observed significant differences in tumor growth in mice implanted with estrogen and DHEA diffusion tubes. CONCLUSIONS: Our results highlight the complex influence of sex steroids on the immune cell composition of prostate tumors. Understanding this biology may help to further personalized therapy and improve patient outcomes.

6.
Asian J Androl ; 24(1): 21-25, 2022.
Article in English | MEDLINE | ID: mdl-34259197

ABSTRACT

Prior research suggests a link between circulating levels of follicle-stimulating hormone (FSH) and prostate cancer outcomes. FSH levels may also explain some of the observed differences in cardiovascular events among men treated with gonadotropin-releasing hormone (GnRH) antagonists compared to GnRH agonists. This study evaluates the association between preoperative FSH and long-term cardiovascular and oncologic outcomes in a cohort of men with long follow-up after radical prostatectomy. We performed a cohort study utilizing an institutional biobank with annotated clinical data. FSH levels were measured from cryopreserved plasma and compared with sex steroids previously measured from the same samples. Differences in oncologic outcomes between tertiles of FSH levels were compared using adjusted cox regression models. Major adverse cardiovascular events (MACE) were similarly assessed using hospital admission diagnostic codes. A total of 492 patients were included, with a median follow-up of 13.1 (interquartile range: 8.9-15.9) years. Dehydroepiandrosterone sulfate (DHEA-S) levels, but not other androgens, negatively correlated with FSH levels on linear regression analysis (P = 0.03). There was no association between FSH tertile and outcomes of biochemical recurrence, time to castrate-resistant prostate cancer, or time to metastasis. MACEs were identified in 50 patients (10.2%), with a mean time to first event of 8.8 years. No association with FSH tertile and occurrence of MACE was identified. Our results do not suggest that preoperative FSH levels are significantly associated with oncologic outcomes among prostate cancer patients treated with radical prostatectomy, nor do these levels appear to be predictors of long-term cardiovascular risk.


Subject(s)
Luteinizing Hormone , Prostatic Neoplasms , Cohort Studies , Follicle Stimulating Hormone , Gonadotropin-Releasing Hormone , Humans , Male , Prostatectomy , Prostatic Neoplasms/surgery
7.
Sci Rep ; 11(1): 19299, 2021 09 29.
Article in English | MEDLINE | ID: mdl-34588590

ABSTRACT

Within the prostate tumor microenvironment (TME) there are complex multi-faceted and dynamic communication occurring between cancer cells and immune cells. Macrophages are key cells which infiltrate and surround tumor cells and are recognized to significantly contribute to tumor resistance and metastases. Our understanding of their function in the TME is commonly based on in vitro and in vivo models, with limited research to confirm these model observations in human prostates. Macrophage infiltration was evaluated within the TME of human prostates after 72 h culture of fresh biopsies samples in the presence of control or enzalutamide. In addition to immunohistochemistry, an optimized protocol for multi-parametric evaluation of cellular surface markers was developed using flow cytometry. Flow cytometry parameters were compared to clinicopathological features. Immunohistochemistry staining for 19 patients with paired samples suggested enzalutamide increased the expression of CD163 relative to CD68 staining. Techniques to validate these results using flow cytometry of dissociated biopsies after 72 h of culture are described. In a second cohort of patients with Gleason grade group ≥ 3 prostate cancer, global macrophage expression of CD163 was unchanged with enzalutamide treatment. However, exploratory analyses of our results using multi-parametric flow cytometry for multiple immunosuppressive macrophage markers suggest subgroup changes as well as novel associations between circulating biomarkers like the neutrophil to lymphocyte ratio (NLR) and immune cell phenotype composition in the prostate TME. Further, we observed an association between B7-H3 expressing tumor-associated macrophages and the presence of intraductal carcinoma. The use of flow cytometry to evaluate ex vivo cultured prostate biopsies fills an important gap in our ability to understand the immune cell composition of the prostate TME. Our results highlight novel associations for further investigation.


Subject(s)
Androgen Antagonists/pharmacology , Benzamides/pharmacology , Biomarkers, Tumor/analysis , Nitriles/pharmacology , Phenylthiohydantoin/pharmacology , Prostatic Neoplasms/therapy , Tumor-Associated Macrophages/drug effects , Aged , Androgen Antagonists/therapeutic use , Benzamides/therapeutic use , Cells, Cultured , Chemotherapy, Adjuvant/methods , Drug Evaluation, Preclinical/methods , Flow Cytometry , Humans , Male , Middle Aged , Nitriles/therapeutic use , Phenylthiohydantoin/therapeutic use , Primary Cell Culture , Prostate/cytology , Prostate/drug effects , Prostate/immunology , Prostate/surgery , Prostatectomy , Prostatic Neoplasms/immunology , Prostatic Neoplasms/pathology , Tumor Microenvironment/drug effects , Tumor-Associated Macrophages/immunology
9.
Prostate ; 79(15): 1767-1776, 2019 11.
Article in English | MEDLINE | ID: mdl-31475741

ABSTRACT

BACKGROUND: The development of phenotypic biomarkers to aid the selection of treatment for patients with castrate-resistant prostate cancer (CRPC) is an important priority. Plasma exosomes have excellent potential as real-time biomarkers to characterize the tumor because they are easily accessible in the blood and contain DNA, RNA, and protein from the parent cell. This study aims to investigate the characteristics of putative prostate-specific plasma extracellular vesicle (EV) markers and their relationship with clinical outcomes. METHODS AND PATIENTS: We investigated plasma EVs in a total of 89 patients with prostate cancer (PCa) at different stages of disease progression. EVs were isolated using both precipitation and ultracentrifugation methods; physical characterization was performed using dynamic light scattering, acetylcholinesterase (AChE) activity, and velocity gradients. An immunocapture method was developed for the evaluation of prostate-specific membrane antigen (PSMA)-positive exosomes. Exosomal messenger RNA (mRNA) was quantified using droplet digital polymerase chain reaction for the expression of KLK3 and androgen receptor splice variant 7 (AR-V7) genes, which code prostate-specific antigen (PSA) and AR-V7, respectively. Serum sex steroids were measured using liquid chromatography-tandem mass spectroscopy. RESULTS: Isolated exosomes from patients with CRPC had a smaller hydrodynamic size than those isolated from localized patients with PCa, while AChE activity showed no difference. Moreover, no differences were observed after initiation of androgen deprivation therapy in serial patient samples. Velocity gradients identified that PSMA-positive exosomes occupied a specific fraction of isolated EVs. A total of 35 patients with CRPC had mRNA analyzed from isolated plasma exosomes. Detectable exosomal KLK3 corresponded with higher concomitant serum PSA measurements, as expected (mean, 112.6 vs 26.61 ng/mL; P = .065). Furthermore, detectable levels of AR-V7 mRNA were associated with a shorter time to progression (median, 16.0 vs 28.0 months; P = .0499). Furthermore, detectable exosomal AR-V7 was significantly associated with testosterone levels below the lower limit of quantification (<0.1 nM). CONCLUSIONS: Our results suggest that exosomal AR-V7 is correlated with lower sex steroid levels in CRPC patients with a poorer prognosis. PSMA immunocapture does not appear sufficient to isolate PCa-specific exosomes.


Subject(s)
Extracellular Vesicles/metabolism , Prostatic Neoplasms, Castration-Resistant/diagnosis , Aged , Aged, 80 and over , Biomarkers, Tumor , Disease Progression , Humans , Kallikreins/metabolism , Male , Middle Aged , Phenotype , Progression-Free Survival , Prostate-Specific Antigen/blood , Prostate-Specific Antigen/metabolism , Prostatic Neoplasms, Castration-Resistant/metabolism , Prostatic Neoplasms, Castration-Resistant/mortality , Prostatic Neoplasms, Castration-Resistant/pathology , Survival Rate
10.
Cell Commun Signal ; 16(1): 39, 2018 07 04.
Article in English | MEDLINE | ID: mdl-29973205

ABSTRACT

BACKGROUND: CRM1 enrichment has been shown to be indicative of invasive as well as chemoresistant tumors. On the other hand, TRAIL, a powerful and specific anti-tumoral agent, has yet to be used effectively to treat gynecological tumors in patients. In the present study, we examined if CRM1, a nuclear exporter capable of mediating protein transport, could be a relevant target to restore chemosensitivity in chemoresistant cells. We thus explored the hypothesis that CRM1-driven nuclear exclusion of tumor suppressors could lead to chemoresistance and that CRM1 inhibitors could present a novel therapeutic approach, allowing sensitization to chemotherapeutic agents. METHODS: Ovarian cancer cell lines, as well as endometrial cancer cell lines, were treated with leptomycin B (LMB), cisplatin and TRAIL, either singly or in combination, in order to induce apoptosis. Western blot and flow cytometry analysis were used to quantify caspases activation and apoptosis induction. Immunofluorescence was used to determine nuclear localization of p53. Colony formation assays were performed to determine therapeutic effectiveness; p53 siRNA were used to establish p53 role in sensitization. Additional information from GEO database and Prognoscan allowed us to contextualise the obtained results. Finally, qRT-PCR was performed to measure apoptotic regulators expression. RESULTS: TRAIL and LMB combination therapy lead to cleavage of caspase-3 as well as the appearance of cleaved-PARP, and thus, apoptosis. Further experiments suggested that sensitization was achieved through the synergistic downregulation of multiple inhibitor of apoptosis, as well as the activation of apoptotic pathways. p53 was enriched in the nucleus following LMB treatments, but did not seem to be required for sensitization; additional experiments suggested that p53 opposed the apoptotic effects of LMB and TRAIL. Results obtained from public data repositories suggested that CRM1 was a driver of chemoresistance and poor prognostic; DR5, on the other hand, acted as as a marker of positive prognostic. CONCLUSIONS: Taken together, our results suggest that the use of CRM1 inhibitors, in combination to chemotherapeutic compounds, could be highly effective in the treatment of gynecological malignancies.


Subject(s)
Apoptosis/drug effects , Endometrial Neoplasms/pathology , Karyopherins/antagonists & inhibitors , Ovarian Neoplasms/pathology , Receptors, Cytoplasmic and Nuclear/antagonists & inhibitors , TNF-Related Apoptosis-Inducing Ligand/pharmacology , Cell Line, Tumor , Cell Survival/drug effects , Cisplatin/pharmacology , Drug Synergism , Fatty Acids, Unsaturated/pharmacology , Female , Humans , Tumor Suppressor Protein p53/metabolism , Exportin 1 Protein
11.
Clin Cancer Res ; 24(21): 5305-5312, 2018 11 01.
Article in English | MEDLINE | ID: mdl-30021911

ABSTRACT

Purpose: Phenotypic biomarkers are a high priority for patients receiving androgen deprivation therapy (ADT) for prostate cancer given the increasing number of treatment options. This study evaluates serum sex steroids as prognostic biomarkers in men receiving ADT for recurrent prostate cancer.Experimental Design: Retrospective cohort study of Canadian patients in the PR.7 trial (accrual 1999-2005) who received continuous ADT for biochemical recurrence postradiotherapy. Patients were excluded with follow-up <2 years or who received estrogens or corticosteroids. Kaplan-Meier and multivariable Cox regression analyses adjusted for baseline prognostic factors assessed time to castration-resistant prostate cancer (CRPC), prostate cancer survival, and overall survival according to tertile of sex steroid measured by mass spectrometry.Results: Post-ADT initiation, we measured samples in 219 patients as well as two subsequent annual samples in a subset of 101 patients. Testosterone levels correlated with androstenedione (AD) and DHT, while DHT, AD, androsterone (AST), dehydroepiandrosterone (DHEA), and androstenediol (A5diol) were highly correlated to each other and negatively associated with age. Higher tertiles of estrone (E1) and estradiol (E2) were significantly associated with sooner time to CRPC. In patients with longitudinal samples, increases in serum DHEA and AST were significantly associated with sooner time to CRPC. Limitations include the number of events for some groups.Conclusions: Our data suggest the patient hormonal milieu has long-term prognostic value in men receiving ADT for recurrent prostate cancer, including increased levels of E1 and E2 and rising DHEA and AST levels, which predict a shorter time to CRPC. Clin Cancer Res; 24(21); 5305-12. ©2018 AACR.


Subject(s)
Gonadal Steroid Hormones/blood , Prostatic Neoplasms/blood , Prostatic Neoplasms/mortality , Aged , Androgen Antagonists/pharmacology , Androgen Antagonists/therapeutic use , Antineoplastic Agents, Hormonal/pharmacology , Antineoplastic Agents, Hormonal/therapeutic use , Antineoplastic Combined Chemotherapy Protocols/adverse effects , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Biomarkers , Combined Modality Therapy , Humans , Kaplan-Meier Estimate , Male , Neoplasm Grading , Neoplasm Recurrence, Local , Neoplasm Staging , Prognosis , Proportional Hazards Models , Prostatic Neoplasms/drug therapy , Prostatic Neoplasms/pathology , Treatment Outcome
12.
Development ; 144(19): 3547-3561, 2017 10 01.
Article in English | MEDLINE | ID: mdl-28827394

ABSTRACT

Hoxa5 is essential for development of several organs and tissues. In the respiratory system, loss of Hoxa5 function causes neonatal death due to respiratory distress. Expression of HOXA5 protein in mesenchyme of the respiratory tract and in phrenic motor neurons of the central nervous system led us to address the individual contribution of these Hoxa5 expression domains using a conditional gene targeting approach. Hoxa5 does not play a cell-autonomous role in lung epithelium, consistent with lack of HOXA5 expression in this cell layer. In contrast, ablation of Hoxa5 in mesenchyme perturbed trachea development, lung epithelial cell differentiation and lung growth. Further, deletion of Hoxa5 in motor neurons resulted in abnormal diaphragm innervation and musculature, and lung hypoplasia. It also reproduced the neonatal lethality observed in null mutants, indicating that the defective diaphragm is the main cause of impaired survival at birth. Thus, Hoxa5 possesses tissue-specific functions that differentially contribute to the morphogenesis of the respiratory tract.


Subject(s)
Homeodomain Proteins/metabolism , Phosphoproteins/metabolism , Respiratory System/embryology , Respiratory System/metabolism , Animals , Animals, Newborn , Body Patterning/genetics , Cartilage/embryology , Cartilage/metabolism , Cell Differentiation/genetics , Crosses, Genetic , Diaphragm/innervation , Diaphragm/metabolism , Diaphragm/ultrastructure , Female , Gene Deletion , Gene Expression Regulation, Developmental , Genotype , Homeodomain Proteins/genetics , Male , Mesoderm/embryology , Mesoderm/metabolism , Models, Biological , Motor Neurons/metabolism , Muscle Development , Muscle Fibers, Skeletal/metabolism , Organ Specificity/genetics , Phosphoproteins/genetics , Respiratory Mucosa/metabolism , SOX9 Transcription Factor/metabolism , Signal Transduction/genetics , Survival Analysis , Trachea/embryology , Trachea/metabolism , Transcription Factors
13.
Med Sci (Paris) ; 30(10): 882-8, 2014 Oct.
Article in French | MEDLINE | ID: mdl-25311023

ABSTRACT

When exposed to environmental stresses, cells activate defence mechanisms to adapt stress and inhibit apoptotic pathways leading to their survival. Stressed cells also reduce their general metabolism in part by inhibiting mRNA translation, thereby saving energy needed to repair stress-induced damages. Under stress conditions, the inhibition of mRNA translation occurs mainly at its initiation step through the phosphorylation of the translation initiation factor eIF2α. One of the four kinases known to phosphorylate eIF2α is heme-regulated inhibitor (HRI). The activation of HRI occurs under conditions of heme deficiency, oxidative stress and treatment with anti-cancer drugs such as proteasome inhibitors. In this article, we discuss the role of HRI in promoting cell resistance to stress-mediated apoptosis.


Subject(s)
Apoptosis/genetics , eIF-2 Kinase/physiology , Animals , Cytoplasmic Granules/metabolism , Erythroblasts/physiology , Heme/physiology , Humans , Oxidative Stress/physiology , Protein Biosynthesis/genetics , Stress, Physiological/physiology
14.
Genes Dev ; 27(18): 2009-24, 2013 Sep 15.
Article in English | MEDLINE | ID: mdl-24065767

ABSTRACT

Histone acetyltransferases (HATs) assemble into multisubunit complexes in order to target distinct lysine residues on nucleosomal histones. Here, we characterize native HAT complexes assembled by the BRPF family of scaffold proteins. Their plant homeodomain (PHD)-Zn knuckle-PHD domain is essential for binding chromatin and is restricted to unmethylated H3K4, a specificity that is reversed by the associated ING subunit. Native BRPF1 complexes can contain either MOZ/MORF or HBO1 as catalytic acetyltransferase subunit. Interestingly, while the previously reported HBO1 complexes containing JADE scaffold proteins target histone H4, the HBO1-BRPF1 complex acetylates only H3 in chromatin. We mapped a small region to the N terminus of scaffold proteins responsible for histone tail selection on chromatin. Thus, alternate choice of subunits associated with HBO1 can switch its specificity between H4 and H3 tails. These results uncover a crucial new role for associated proteins within HAT complexes, previously thought to be intrinsic to the catalytic subunit.


Subject(s)
Histone Acetyltransferases/metabolism , Histones/metabolism , Acetylation , Adaptor Proteins, Signal Transducing/metabolism , Amino Acid Sequence , Chromatin/metabolism , DNA-Binding Proteins , HEK293 Cells , HeLa Cells , Histone Acetyltransferases/chemistry , Histone Acetyltransferases/genetics , Homeodomain Proteins/metabolism , Humans , Methylation , Molecular Sequence Data , Nuclear Proteins/metabolism , Protein Binding , Protein Structure, Tertiary , Protein Subunits/chemistry , Protein Subunits/metabolism , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Sequence Alignment , Substrate Specificity , Transcription Factors/chemistry , Transcription Factors/metabolism , Tumor Suppressor Proteins/chemistry , Tumor Suppressor Proteins/metabolism
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