PSA secretion and cell proliferation are affected by NCoR1 silencing in prostate cancer cells

Introduction: The androgen receptor (AR) plays an important role in normal development of the prostate gland, as well as in prostatic neoplasms. Transcriptional regulation by AR is modulated by its interaction with co-activators or co-repressors, such as NCoR1 (nuclear receptor co-repressor 1), which is involved in reducing AR activity over the target gene transcription. Methods: To identify the role of NCoR1 in the prostate cancer androgen independence in a cell line model, we aimed to evaluate the effects of silencing NCoR1 on prostate-specific antigen (PSA) gene expression, the proliferative response and PSA secretion on the supernatant of C4-2B and LNCaP cells that were submitted to small interfering RNAs (siRNAs) transfection, and to treatments with different androgen dosages. Results: In LNCaP and C4-2B cells with no dihydrotestosterone (DHT) treatment, a decrease in PSA mRNA expression was observed 48 hours and 72 hours after gene silencing in the siNCoR group when compared to the control and siNC groups. The LNCaP and C4-2B cells showed a biphasic pattern in response to dihydrotestosterone treatment in transfected groups (siNCoR and siNC) as well as in the control condition (without transfection). The secretion of PSA in cell supernatant of LNCaP and C4-2B cells was higher in the siNCoR group, and, in relation to hormonal treatment, higher in the 10-8 M DHT group. Conclusions: A reduction in the NCoR1 levels seems to have a double influence on the activity of AR in PCa cells. These results suggest that NCoR may act as an AR co-repressor depending upon hormonal stimulation.(AU)

Receptor-interacting protein 140 overexpression promotes neuro-2a neuronal differentiation by ERK1/2 signaling / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Abnormal neuronal differentiation plays an important role in central nervous system (CNS) development abnormalities such as Down syndrome (DS), a disorder that results directly from overexpression of genes in trisomic cells. Receptor-interacting protein 140 (RIP140) is significantly upregulated in DS brains, suggesting its involvement in DS CNS development abnormalities. However, the role of RIP140 in neuronal differentiation is still not clear. The current study aimed to investigate the effect of RIP140 overexpression on the differentiation of neuro-2a (N2a) neuroblastoma cells, in vitro.</p><p><b>METHODS</b>Stably RIP140-overexpressing N2a (N2a-RIP140) cells were used as a neurodevelopmental model, and were constructed by lipofection and overexpression validated by real-time polymerase chain reaction and Western blot. Retinoic acid (RA) was used to stimulate N2a differentiation. Combining the expression of Tuj1 at the mRNA and protein levels, the percentage of cells baring neurites, and the number of neurites per cell body was semi-quantified to determine the effect of RIP140 on differentiation of N2a cells. Furthermore, western blot and the ERK1/2 inhibitor U0126 were used to identify the specific signaling pathway by which RIP140 induces differentiation of N2a cells. Statistical significance of the differences between groups was determined by one-way analysis of variance followed by the Dunnett test.</p><p><b>RESULTS</b>Compared to untransfected N2a cells RIPl40 expression in N2a-RIP140 cells was remarkably upregulated at both the mRNA and protein levels. N2a-RIP140 cells had a significantly increased percentage of cells baring neurites, and numbers of neurites per cell, as compared to N2a cells, in the absence and presence of RA (P < 0.05). In addition, Tuj1, a neuronal biomarker, was strongly upregulated in N2a-RIP140 cells (P < 0.05) and phosphorylated ERK1/2 (p-ERK1/2) levels in N2a-RIP140 cells were dramatically increased, while differentiation was inhibited by the ERK1/2-specific inhibitor U0126.</p><p><b>CONCLUSIONS</b>RIP140 overexpression promotes N2a cell neuronal differentiation by activating the ERK1/2 pathway.</p>

Inhibitory effect of genistein on the proliferation of Raji cells and its related mechanism / 中国实验血液学杂志

This study was aimed to investigate the anti-proliferative effect of genistein (Gen) on BCL-6 positive Raji cells and its related mechanism. Trypan blue staining and MTT method were used to analyze the anti-proliferative effect of Gen on Raji cells. Cell apoptosis, protein expression and the interaction of BCL-6 and NCoR were detected by PI/AV dual staining, Western blot and Co-IP method, respectively. The results showed that Gen had time- and dose-dependent inhibitory effect on Raji cell proliferation and induced apoptosis. Different dose of Gen had no significant effect on the expression of BCL-6 and NCoR, but could inhibit the binding of BCL-6 and NCoR. It is concluded that Gen shows inhibitory effect on BCL-6 positive lymphoma cells, which can be as a adjuvant therapy for combined rituximab with chemotherapy.

Nuclear corepressor 1 expression predicts response to first-line endocrine therapy for breast cancer patients on relapse / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Estrogen receptor alpha (ER alpha) is the most important endocrine therapy responsiveness predictor for women with breast cancer. The accuracy of the prediction of the response to endocrine therapy was thought to be affected by involving the estrogen receptor coregulatory proteins and cross-talk between ER and other growth factor-signaling networks. Nuclear corepressor 1 (NCOR1) is one of the ER a transcription repressor. The objective of the study is to investigate the expression of NCOR1 at the protein level and pursue its predictive value for breast cancer endocrine therapy.</p><p><b>METHODS</b>In the present study, the level of expression of NCOR1 protein has been assessed by immunohistochemistry in 104 cases of invasive carcinoma of the breast. Associations between NCOR1 protein expression and different clinicopathological factors and survival were sought.</p><p><b>RESULTS</b>It was found that NCOR1 was expressed at significantly higher levels in responsive patients treated with endocrine therapy as first-line treatment on relapse. Responsive patients also had a significantly longer post-relapse survival and overall survival. No NCOR1 expression difference was found between patient by age, tumor size, lymph node status, different histological grade groups and human epidermal growth factor receptor 2 (HER2) status. Multivariate analysis showed that NCOR1 is an independent prognostic factor for over-all survival.</p><p><b>CONCLUSIONS</b>In breast cancer, NCOR1 protein expression level predicts response to endocrine therapy as first-line treatment for breast cancer patients on relapse and NCOR1 protein level assay may increase the accuracy in the endocrine treatment determination and, therefore, improving the patients survival.</p>

Determination of ETO interaction domain within nuclear receptor co-repressor / 中华血液学杂志

<p><b>OBJECTIVE</b>To determine the ETO-interaction domain of nuclear receptor co-repressor (N-CoR) for abolishing the biological function of AML1-ETO.</p><p><b>METHODS</b>Ten different regions of N-CoR (N-CoRYs) were generated by means of polymerase chain reaction (PCR), and cloned into yeast expression plasmid pGADGL to construct pGADGL/N-CoRYs. The yeast two-hybrid technique and X-gal staining were used to determine the binding between the 10 different regions of N-CoR and ETO.</p><p><b>RESULTS</b>It was shown that the co-existence of 988-1,126 and 1,551-1,803 amino acid residues of N-CoRY was the ETO-interaction domains required for the binding with ETO.</p><p><b>CONCLUSION</b>Two domains of N-CoR that interact with two zinc fingers of ETO, and keep stable binding between the two proteins were identified.</p>