RESUMO
Recent research in epigenetics suggests that defects in epigenetic regulation of ribosomal DNA (rDNA) transcription may contribute to tumorigenesis. ATRX/DAXX complex is involved in the establishment and maintenance of the silence of the rDNA gene through H3K9me3 modification at histone variant H3.3. The ATRX/DAXX-related genes are frequently mutated in some types of tumors, which may increase rDNA transcription and promote cancer development and progression. In this review, we focus on the mechanism that abnormal transcription of rDNA potentially influences tumorigenesis. We also summarize the epigenetic regulatory mechanism of rDNA transcription, which may provide new theoretical support for drug development based on rDNA transcriptional regulation.
Assuntos
Carcinogênese/genética , DNA Ribossômico/genética , Epigênese Genética , Proteínas Nucleares , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Correpressoras , Histonas , Humanos , Chaperonas Moleculares , Proteínas Nucleares/genética , Proteína Nuclear Ligada ao X/genéticaRESUMO
Somatic cell nuclear transfer (SCNT) is an important technique for life science research. However, most SCNT embryos fail to develop to term due to undefined reprogramming defects. Here, we show that abnormal Xi occurs in somatic cell NT blastocysts, whereas in female blastocysts derived from cumulus cell nuclear transfer, both X chromosomes were inactive. H3K27me3 removal by Kdm6a mRNA overexpression could significantly improve preimplantation development of NT embryos, and even reached a 70.2% blastocyst rate of cleaved embryos compared with the 38.5% rate of the control. H3K27me3 levels were significantly reduced in blastomeres from cloned blastocysts after overexpression of Kdm6a. qPCR indicated that rDNA transcription increased in both NT embryos and 293T cells after overexpression of Kdm6a. Our findings demonstrate that overexpression of Kdm6a improved the development of cloned mouse embryos by reducing H3K27me3 and increasing rDNA transcription.
Assuntos
Blastocisto/fisiologia , Regulação da Expressão Gênica no Desenvolvimento , Histona Desmetilases/genética , Lisina/metabolismo , Técnicas de Transferência Nuclear , Animais , Clonagem de Organismos/métodos , Células do Cúmulo/citologia , DNA Ribossômico/genética , Feminino , Células HEK293 , Histona Desmetilases/metabolismo , Histonas/genética , Histonas/metabolismo , Humanos , Masculino , Camundongos Endogâmicos , Inativação do Cromossomo XRESUMO
Histones are a class of evolutionarily conserved nuclear proteins. Histone octamer wrapped by DNA sequence forms the nucleosome, the basic building blocks of eukaryotic chromatin. The nucleosomes keep the DNA in a condensed state, maintain the integrity of the genome, and ensure proper DNA replication, transcription, recombination and repair. Nucleosomes can regulate the biological processes of the cell through a number of distinct post-translational modifications (PTMs) and turnovers of histone variants. Although the histone H3 variant H3.3 differs from the canonical histone H3 by only a few amino acids, it could be incorporated into distinct chromatin regions by specific chaperones and exert diverse functions on the chromatin. Importantly, H3.3 is also an essential maternal factor, and plays a key role in cellular reprogramming during fertilization and somatic cell nuclear transfer. In this review, we summarize the structural properties and enrichment pattern of H3.3, and explore the specific chaperones involved in the H3.3-mediated cellular reprogramming. We hope to provide some insights on new means to improve the efficiency of somatic cell reprogramming and lay the foundation for its potential applications.
Assuntos
Reprogramação Celular , Histonas/metabolismo , Animais , Cromatina/genética , Cromatina/metabolismo , Histonas/genética , Humanos , Nucleossomos/genética , Nucleossomos/metabolismoRESUMO
To explore the feasibility of endoscopic thyroidectomy via breast areola and axilla approach. The clinical data of 36 cases that underwent endoscopic thyroidectomy via breast areola and axilla approach from February 2012 to December 2013 were reviewed. All cases were completed, the mean operation time was 136.3 min (95-183 min), intraoperative blood loss was 15.8 ml (5-60 ml). The average hospitalization time was 5 days (4-6 days). There were no conversions to open surgery, no permanent nerve injuries, and no cases of hypoparathyroidism. Three patients had postoperative subcutaneous ecchymosis who were cured spontaneously after 1 month. Endoscopic thyroidectomy is safe and feasible for patients with thyroid diseases with good cosmetic results, and is worthy of being widely applied for patients who have cosmetic demand.
Assuntos
Axila , Endoscopia/métodos , Mamilos , Tireoidectomia/métodos , Adolescente , Adulto , Perda Sanguínea Cirúrgica , Estudos de Viabilidade , Feminino , Humanos , Pessoa de Meia-Idade , Duração da Cirurgia , Doenças da Glândula Tireoide/cirurgia , Adulto JovemRESUMO
During fertilization, DAXX (death domain-associated protein) mediates histone variant H3.3 incorporation into heterochromatin, which plays an important role in the maintenance of genomic integrity. rDNA, the ribosomal gene, is included in the first wave of gene activation after fertilization. Our and other studies indicated that loss of Daxx disturbs rDNA heterochromatinization and promotes rDNA transcription without change in protein expression of H3.3. However, maternal and zygotic deletion of Daxx impairs blastocyst development. Whether Daxx knockdown affects H3.3 expression and improves the rDNA transcription in preimplantation development has not been reported. In the present study, we injected HA-labelled H3.3 (H3.3-HA) into oocytes during ICSI procedure, and detected H3.3 and DAXX by immunofluorescent staining. Then, we knockdowned Daxx and detected the gene expression levels of Daxx, H3.3, 18s and 47s rRNA. We also performed immunofluorescent staining of B23, γH2A and EdU incorporation to demonstrate nuclear structure, DNA damage and replication. We found injection of H3.3-HA did not impair preimplantation development. Daxx siRNA did not change expression of H3.3 mRNA, and the development of two-cell embryos and blastocysts, but the overall replication and expression levels of rRNA were increased compared with that in the control group. Finally, knockdown of DAXX did not aggravate the DNA damage but loosened the nucleolus. We concluded that Daxx knockdown promoted DNA replication and rDNA transcription, but did not affect H3.3 expression and subsequent preimplantation development.
Assuntos
Heterocromatina , Histonas , Camundongos , Animais , DNA Ribossômico/genética , DNA Ribossômico/metabolismo , Histonas/genética , Histonas/metabolismo , Heterocromatina/metabolismo , Blastocisto , Desenvolvimento Embrionário , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Proteínas Correpressoras/genética , Proteínas Correpressoras/metabolismoRESUMO
Whether the expression status of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER-2) receptor and Ki-67 show concordance between the primary tumors and the synchronous axillary lymph node (ALN) metastases has been discussed in numerous studies. However, to date, the results of these studies remain controversial. Therefore, the present study aimed to investigate whether the expression of ER, PR, HER-2 and Ki-67 was in concordance between the primary tumors and synchronous ALN metastases in patients with operable breast cancer (BC). A total of 60 tissue samples were collected from patients with primary operable BC diagnosed with primary tumors and synchronous ALN metastases. The expression levels of the four biomarkers, ER, PR, HER-2 and Ki-67, were assessed in primary lesions and synchronous ALN metastases samples using immunohistochemistry. The cut-off values were set to 10% for ER and PR, while the labeling index of Ki-67 was set to 14%. The immunostaining intensity of ER and PR was scored as negative (-), 1+, 2+ and 3+. The criteria for HER-2 testing in BC were implemented according to the American Society of Clinical Oncology (ASCO) and the College of American Pathologists (CAP) guidelines. The concordance rates for ER, PR and HER-2 were 96.7 (58/60), 96.7 (58/60) and 90% (54/60), respectively. In addition, the kappa values of consistency in the primary lesions and the synchronous ALN metastases were 0.773 for ER, 0.654 for PR and 0.785 for HER-2. Furthermore, the P-values of ER, PR and Ki-67 numerical variables between the two groups were 0.393, 0.400 and 0.331, respectively, as demonstrated using a non-parametric Wilcoxon signed rank test. The findings of the present study demonstrated a high degree of concordance between the expression of ER, PR, HER-2 and Ki-67 in the primary tumors and that in the synchronous ALN metastases, suggesting that the BC primary tumor biomarkers may be used for the prognosis of synchronous ALN metastases in patients with operable BC.
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Up to accomplishment of this study, the role of long non-coding RNAs (lncRNAs) in breast cancer has been investigated in several researches. Nevertheless, its association with the chemosensitivity of cancer was little known. Therefore, this study is focused on lncRNA GAS5 and its influence in the chemosensitivity of triple-negative breast cancer (TNBC). Expression of GAS5 in TNBC tissues and cells was detected by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and its methylation was evaluated using methylation-specific polymerase chain reaction (MSP). Moreover, in order to define the contributory role of GAS5 in TNBC, GAS5 expression, proliferation, and apoptosis of TNBC cells were detected by a series of experiment. Finally, the effects of GAS5 in vivo were investigated by measuring tumor formation in nude mice. GAS5 was poorly expressed in TNBC tissues and cells, which could regulate the progression of TNBC. The methylation of CpG island in the promoter region of GAS5 in MDA-MB-231 and MDA-MB-468 cells was decreased, while GAS5 expression in cells was increased. Overexpressed GAS5 reduced the inhibitory concentration (IC50) value and the cell proliferation of TNBC, and promoted their apoptosis, so as to delay the progression of TNBC. Our study provides evidence that up-regulated GAS5 suppressed the progression of TNBC and promoted chemosensitivity and apoptosis of TNBC cells. Thus, GAS5 may be a potential candidate for the treatment of TNBC.
Assuntos
Apoptose/genética , Resistencia a Medicamentos Antineoplásicos/genética , RNA Longo não Codificante/metabolismo , Neoplasias de Mama Triplo Negativas/metabolismo , Regulação para Cima/genética , Adulto , Idoso , Animais , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/genética , Progressão da Doença , Feminino , Xenoenxertos , Humanos , Concentração Inibidora 50 , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Pessoa de Meia-Idade , RNA Longo não Codificante/genética , Sais de Tetrazólio/farmacologia , Transfecção , Neoplasias de Mama Triplo Negativas/patologiaRESUMO
INTRODUCTION: The aim of this study was to evaluate the expression of C-type lectin domain family 3 member A (CLEC3A) and its clinical significance in breast invasive ductal cancer (IDC) as well as its effect on breast cancer (BC) cell proliferation and metastasis. In this study, the level of CLEC3A expression in The Cancer Genome Atlas (TCGA) datasets was analyzed. MATERIALS AND METHODS: Clinical collected samples and BC cells were measured using quantitative reverse transcription polymerase chain reaction. Its correlations with patients' clinicopathological characteristics were analyzed by Pearson's chi-squared test. Overall survival (OS) analysis was performed by the Kaplan-Meier method and Cox's proportional-hazards model. BC cell proliferation, migration, and invasion by CLEC3A knockdown were assessed using Cell Counting Kit-8 and colony formation assay, wound healing model and transwell assay, respectively, in BT474 cell line. Activities of survival factors and phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT) signaling were measured by testing key molecules using Western blot assay. RESULTS: CLEC3A expression was markedly higher in breast IDC tissues than normal breast tissues or adjacent normal tissue. Patients with high CLEC3A expression related to higher lymph node and poorer OS of breast IDC. CLEC3A knockdown by siRNA could inhibit the BC cells BT474 proliferation, migration, and invasion, together with a decrease in expression of key proteins in survival factors and PI3K/AKT signaling pathway. CONCLUSION: Elevated CLEC3A expression may correlate with breast IDC metastatic potential and indicated a poor prognosis in breast IDC. CLEC3A knockdown inhibited BC cell growth and metastasis might be through suppressing PI3K/AKT signaling activity. These findings unravel that CLEC3A is a promising therapeutic target for BC in the future.