Yin-Yang-1 decreases Fas-induced apoptosis in acute lymphoblastic leukemia under hypoxic conditions: its implications in immune evasion / YY1 induce la disminución de la apoptosis a través de Fas en la leucemia linfoblástica aguda en condiciones hipóxicas: implicaciones en la evasión de la respuesta inmunitaria

Abstract Background: Acute lymphoblastic leukemia (ALL) is an aggressive malignant disease with high prevalence in pediatric patients. It has been shown that the downregulation of Fas expression is correlated with an inadequate response in ALL, although these mechanisms are still not well understood. Several reports demonstrated that hypoxia is involved in dysfunctional apoptosis. Yin-Yang-1 (YY1) transcription factor is involved in resistance to apoptosis, tumor progression, and it is increased in different types of cancer, including leukemia. The regulatory mechanism underlying YY1 expression in leukemia is still not understood, but it is known that YY1 negatively regulates Fas expression. The study aimed to evaluate the effect of YY1 on Fas expression under hypoxic conditions in ALL. Methods: Leukemia cell line RS4; 11 was cultured under normoxic and hypoxic conditions. YY1, Fas receptor, and hypoxia-inducible factor (HIF-1α) expression were analyzed. After treatment with a Fas agonist (DX2), apoptosis was analyzed through the detection of active caspase 3. Data were analyzed using Pearson’s correlation. Results: Leukemia cells co-expressed both HIF-1α and YY1 under hypoxia, which correlated with a downregulation of Fas expression. During hypoxia, the levels of apoptosis diminished after DX2 treatment. The analysis revealed that patients with high levels of HIF-1α also express high levels of YY1 and low levels of Fas. Conclusions: These results suggest that YY1 negatively regulates the expression of the Fas receptor, which could be involved in the escape of leukemic cells from the immune response contributing to the ALL pathogenesis.

Resumen Introducción: La leucemia linfoblástica aguda (LLA) es una enfermedad con alta prevalencia en la población pediátrica. El mecanismo por el cual el receptor de Fas participa en la regulación inmunitaria en los tumores es desconocido, pero se sabe que está subexpresado en LLA. El factor de transcripción Ying-Yang-1 (YY1) está involucrado en la resistencia a la apoptosis y la progresión tumoral; se encuentra aumentado en diferentes tumores, incluida la LLA. Aunque los mecanismos que regulan la expresión de YY1 en LLA son desconocidos, se sabe que YY1 regula la expresión del receptor de Fas. El objetivo de este trabajo fue evaluar el efecto de YY1 en la expresión de Fas en condiciones de hipoxia en la LLA. Métodos: Se cultivaron células RS4;11 en condiciones de hipoxia y se analizó la expresión de YY1, receptor de Fas y HIF-1α. La apoptosis fue inducida usando un agonista de Fas (DX2) y se analizó con la detección de caspasa 3 activa. Los datos se analizaron mediante correlación de Pearson. Resultados: Las células RS4;11 coexpresaron HIF-1αy YY1 en hipoxia, lo cual correlaciona con una baja expresión de Fas. La apoptosis se encontró disminuida durante condiciones de hipoxia, después del tratamiento con DX2. El análisis bioinformático mostró que los pacientes con altos niveles de HIF-1αpresentan YY1 elevado y bajos niveles del receptor de Fas. Conclusiones: Estos resultados sugieren que YY1 regula negativamente la expresión del receptor de Fas, lo cual podría estar involucrado en el escape de las células leucémicas a la respuesta inmunitaria, contribuyendo a la patogénesis de la LLA.

Human INO80/YY1 chromatin remodeling complex transcriptionally regulates the BRCA2- and CDKN1A-interacting protein (BCCIP) in cells

The BCCIP (BRCA2- and CDKN1A-interacting protein) is an important cofactor for BRCA2 in tumor suppression. Although the low expression of BCCIP is observed in multiple clinically diagnosed primary tumor tissues such as ovarian cancer, renal cell carcinoma and colorectal carcinoma, the mechanism of how BCCIP is regulated in cells is still unclear. The human INO80/YY1 chromatin remodeling complex composed of 15 subunits catalyzes ATP-dependent sliding of nucleosomes along DNA. Here, we first report that BCCIP is a novel target gene of the INO80/YY1 complex by presenting a series of experimental evidence. Gene expression studies combined with siRNA knockdown data locked candidate genes including BCCIP of the INO80/YY1 complex. Silencing or over-expressing the subunits of the INO80/YY1 complex regulates the expression level of BCCIP both in mRNA and proteins in cells. Also, the functions of INO80/YY1 complex in regulating the transactivation of BCCIP were confirmed by luciferase reporter assays. Chromatin immunoprecipitation (ChIP) experiments clarify the enrichment of INO80 and YY1 at +0.17 kb downstream of the BCCIP transcriptional start site. However, this enrichment is significantly inhibited by either knocking down INO80 or YY1, suggesting the existence of both INO80 and YY1 is required for recruiting the INO80/YY1 complex to BCCIP promoter region. Our findings strongly indicate that BCCIP is a potential target gene of the INO80/YY1 complex.

Expression of YY 1 protein in human insulinoma and its clinical implication / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the expression of Yin Yang 1 (YY1) protein in human insulinoma and explore its clinical significance.</p><p><b>METHODS</b>Nineteen pancreatic neuroendocrine tumor tissue were collected from patients treated in Nanfang Hospital between 2000 and 2014. The protein expression of YY1 in benign and malignant insulinoma tissues were detected by immunohistochemistry.</p><p><b>RESULTS</b>Positive expression for YY1 protein was detected in both benign and malignant tumor tissues, but the malignant tissues had a significantly greater intensity of YY1 expression than the benign tissues (P=0.042). The intensity of YY1 expression was positively correlated with the nature of the tumor, and the insulinomas with high expressions of YY1 had significantly greater malignant potentials (P=0.037).</p><p><b>CONCLUSION</b>The high expression of YY1 protein is associated with the development of insulinima. YY1 may serve as a new tumor marker for detecting the malignant transformation of insulinoma.</p>

Regulation and Function of the Peg3 Imprinted Domain

A subset of mammalian genes differ functionally between two alleles due to genomic imprinting, and seven such genes (Peg3, Usp29, APeg3, Zfp264, Zim1, Zim2, Zim3) are localized within the 500-kb genomic interval of the human and mouse genomes, constituting the Peg3 imprinted domain. This Peg3 domain shares several features with the other imprinted domains, including an evolutionarily conserved domain structure, along with transcriptional co-regulation through shared cis regulatory elements, as well as functional roles in controlling fetal growth rates and maternal-caring behaviors. The Peg3 domain also displays some unique features, including YY1-mediated regulation of transcription and imprinting; conversion and adaptation of several protein-coding members as ncRNA genes during evolution; and its close connection to human cancers through the potential tumor suppressor functions of Peg3 and Usp29. In this review, we summarize and discuss these features of the Peg3 domain.

Expression of hsa-miR-186 and its role in human colon carcinoma cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the expression of hsa-mir-186 in colorectal cancer and study its role in regulating the biological behaviors of human colorectal cancer SW620 cells in vitro.</p><p><b>METHODS</b>The expression of hsa-miR-186 in colon cancer tissue and the adjacent tissues as well as 5 colon carcinoma cells were analyzed using real-time quantitative RT-PCR. The precursor sequence of miR-186 gene was amplified from the genomic DNA by PCR and cloned into the lentiviral vector PLVTHM labeled with GFP. The colorectal cancer cell line SW620 was transfected with PLVTHM-miR186 vector and the lentivirus-infected cells were sorted with flow cytometry. Cell counting kit-8 (CCK-8) assay was used to detect the proliferation of the cells. The migration and invasion of SW620 cells were investigated using Transwell assay and scratch test. Western blotting was used to detect the expression of YY1 protein in SW620 cell lines.</p><p><b>RESULTS</b>The relative expression of miR-186 in the cancer tissues was 0.0024∓0.0027, significantly lower than that in the adjacent tissues (0.066∓0.068, P=0.008); the relative expression level of hsa-miR-186 in SW620 and LoVo cells with a high metastatic potential was 0.118∓0.138 and 0.157∓0.001, respectively, significantly lower than that in HT-29 cells with a low metastatic potential (1.000∓0.00, P<0.05). The recombinant lentiviral vector PLVTHM-miR186, verified by enzyme digestion, sequencing and qPCR, caused significant inhibition of cell proliferation, migration and invasion and suppressed the expression of YY1 protein in SW620 cells.</p><p><b>CONCLUSION</b>As a tumor suppressor gene, Hsa-miR-186 is down-regulated in colon carcinoma tissues and in highly metastatic SW620 and LoVo cells. Has-miR-186 can inhibit the cell proliferation, migration and invasion of colon carcinoma cells in vitro possibly by suppressing YY1 expression.</p>

Effects of DLL4 gene on YY1 and c-Myc protein expression and cell proliferation in leukemia cell line K562 / 中国实验血液学杂志

This study was aimed to explore the effects of Notch ligand DLL4 on the protein expression of the transcription factor YY1 and proto-oncogene c-Myc, as well as K562 cell proliferation. The experiment was divided into 3 groups: normal control, negative control (pBudCE4.1-transfected) and experimental (pBudCE4.1-DLL4-transfected) groups. At 48 hours after transfection, the expression level of DLL4, YY1 and c-Myc proteins in K562 cells of each group were detected by Western blot and indirect immunocytochemical method; the CCK-8 method was used to detect proliferation of K562 cells; at 48 hours after transfection, cell cycle distribution and apoptosis of K562 cells were detected by flow cytometry. The results showed that the protein expression of DLL4, YY1 and c-Myc in K562 cells of every group were found. The protein expression levels of DLL4, YY1 and c-Myc in the experimental group cells were significantly higher than that in control groups (p < 0.05). The cell number in G(0)/G(1) phase increased in the experimental group and was higher than that in the control groups (p < 0.001), and the number of apoptotic cells were also increased (p < 0.001). It is concluded that DLL4 gene was successfully transfected into K562 cells, which increased the protein expression levels of transcription factor YY1 and proto-oncogene c-Myc, leading to the cell proliferation slower in experiment group, inducing the cell cycle arrested in G(0)/G(1) phase and increasing apoptosis.