NRIP1 regulates cell proliferation in lung adenocarcinoma cells.

Nuclear receptor interacting protein 1 (NRIP1) is a transcription cofactor that regulates the activity of nuclear receptors and transcription factors. Functional expression of NRIP1 has been identified in multiple cancers. However, the expression and function of NRIP1 in lung adenocarcinoma have remained unclear. Thus, we aimed to clarify the NRIP1 expression and its functions in lung adenocarcinoma cells. NRIP1 and Ki-67 were immunostained in the tissue microarray section consisting of 64 lung adenocarcinoma cases, and the association of NRIP1 immunoreactivity with clinical phenotypes was examined. Survival analysis was performed in lung adenocarcinoma data from The Cancer Genome Atlas (TCGA). Human A549 lung adenocarcinoma cell line with an NRIP1-silencing technique was used in vitro study. Forty-three of 64 cases were immunostained with NRIP1. Ki-67-positive cases were more frequent in NRIP1-positive cases as opposed to NRIP1-negative cases. Higher NRIP1 mRNA expression was associated with poor prognosis in the TCGA lung adenocarcinoma data. NRIP1 was mainly located in the nucleus of A549 cells. NRIP1 silencing significantly reduced the number of living cells, suppressed cell proliferation, and induced apoptosis. These results suggest that NRIP1 participates in the progression and development of lung adenocarcinoma. Targeting NRIP1 may be a possible therapeutic strategy against lung adenocarcinoma.

Circular RNA nuclear receptor interacting protein 1 promoted biliary tract cancer epithelial-mesenchymal transition and stemness by regulating the miR-515-5p/AKT2 axis and PI3K/AKT/mTOR signaling pathway.

Biliary tract cancer (BTC) is a devastating malignancy that is notoriously difficult to diagnose and is associated with high mortality. Circular RNA (circRNA) is a class of endogenous non-coding RNA which has been regarded as the key regulator of tumor initiation and progression, including BTC. Circular RNA nuclear receptor interacting protein 1 (circ_NRIP1), as a circular RNA, is abnormally expressed in many human tumors and exhibits diverse functions in cancer progression. However, its biological significance in BTC has not been thoroughly investigated. In this research, we elucidated that circ_NRIP1 was notably overexpressed in both BTC tissues and cells. We further established a correlation between circ_NRIP1 expression and clinicopathological features in BTC patients, highlighting its clinical relevance. Through functional assays, we observed that knockdown of circ_NRIP1 significantly inhibited tumor cell proliferation, invasion, stemness maintenance, and epithelial-mesenchymal transition, indicating its active involvement in promoting BTC progression. Additionally, it attenuated growth of xenograft and metastasis models. Mechanically, we revealed that circ_NRIP1 served as the competing endogenous RNA to sequester miR-515-5p through complementary base pairing mechanism, thereby upregulated AKT2 expression and indirectly activated PI3K/AKT/mTOR signaling pathway. Generally, targeting the circ_NRIP1/miR-515-5p/AKT2 axis and aberrant activation of the PI3K/AKT/mTOR pathway may hold promising therapeutic strategies for BTC. Our research contributes to a better understanding of the underlying biological basis of BTC and paves the way for the development of innovative treatment approaches.

Tumor Promoting Role of NRIP1 in Oral Squamous Cell Carcinoma: The Involvement of NSD2-Mediated Histone Methylation of DGCR8.

Oral squamous cell carcinoma (OSCC) remains the most prevalent malignance in the head and neck with highly aggressive attributes. This study investigates the functions of nuclear receptor interacting protein 1 (NRIP1) and its target transcripts in the progression of OSCC. By analyzing four OSCC-related Gene Expression Omnibus (GEO) datasets (GSE9844, GSE23558, GSE25104 and GSE74530) and querying bioinformatics systems, we obtained NRIP1 as an aberrantly highly expressed transcription factor in OSCC. Increased NRIP1 was detected in OSCC cell lines. Artificial downregulation of NRIP1 significantly suppressed proliferation, migration and invasion, resistance to apoptosis, tumorigenicity, and in vivo metastatic potential of OSCC cells. Moreover, the bioinformatics analyses suggested nuclear receptor binding SET domain protein 2 (NSD2) as a target of NRIP1 and DGCR8 microprocessor complex subunit (DGCR8) as a target of NSD2. Indeed, we validated by chromatin immunoprecipitation and luciferase assays that NRIP1 activated the transcription of NSD2, and NSD2 increased DGCR8 transcription by modulating histone methylation near the DGCR8 promoter. Either NSD2 or DGCR8 upregulation in OSCC cells rescued their malignant properties. Collectively, this study demonstrates that NRIP1 augments malignant properties of OSCC cells by activating NSD2-mediated histone methylation of DGCR8.

RIP140 deficiency enhances cardiac fuel metabolism and protects mice from heart failure.

During the development of heart failure (HF), the capacity for cardiomyocyte (CM) fatty acid oxidation (FAO) and ATP production is progressively diminished, contributing to pathologic cardiac hypertrophy and contractile dysfunction. Receptor-interacting protein 140 (RIP140, encoded by Nrip1) has been shown to function as a transcriptional corepressor of oxidative metabolism. We found that mice with striated muscle deficiency of RIP140 (strNrip1-/-) exhibited increased expression of a broad array of genes involved in mitochondrial energy metabolism and contractile function in heart and skeletal muscle. strNrip1-/- mice were resistant to the development of pressure overload-induced cardiac hypertrophy, and CM-specific RIP140-deficient (csNrip1-/-) mice were protected against the development of HF caused by pressure overload combined with myocardial infarction. Genomic enhancers activated by RIP140 deficiency in CMs were enriched in binding motifs for transcriptional regulators of mitochondrial function (estrogen-related receptor) and cardiac contractile proteins (myocyte enhancer factor 2). Consistent with a role in the control of cardiac fatty acid oxidation, loss of RIP140 in heart resulted in augmented triacylglyceride turnover and fatty acid utilization. We conclude that RIP140 functions as a suppressor of a transcriptional regulatory network that controls cardiac fuel metabolism and contractile function, representing a potential therapeutic target for the treatment of HF.

ALKBH5-induced circular RNA NRIP1 promotes glycolysis in thyroid cancer cells by targeting PKM2.

Although circular RNAs (circRNAs) are involved in cell proliferation, differentiation, apoptosis, and invasion, the underlying regulatory mechanisms of circRNAs in thyroid cancer have not been fully elucidated. This article aimed to study the role of circRNA regulated by N6-methyladenosine modification in papillary thyroid cancer (PTC). Quantitative real-time PCR, western blotting, and immunohistochemistry were used to investigate the expressions of circRNA nuclear receptor-interacting protein 1 (circNRIP1) in PTC tissues and adjacent noncancerous thyroid tissues. In vitro and in vivo assays were carried out to assess the effects of circNRIP1 on PTC glycolysis and growth. The N6-methyladenosine mechanisms of circNRIP1 were evaluated by methylated RNA immunoprecipitation sequencing, luciferase reporter gene, and RNA stability assays. Results showed that circNRIP1 levels were significantly upregulated in PTC tissues. Furthermore, elevated circNRIP1 levels in PTC patients were correlated with high tumor lymph node metastasis stage and larger tumor sizes. Functionally, circNRIP1 significantly promoted glycolysis, PTC cell proliferation in vitro, and tumorigenesis in vivo. Mechanistically, circNRIP1 acted as a sponge for microRNA (miR)-541-5p and miR-3064-5p and jointly upregulated pyruvate kinase M2 (PKM2) expression. Knockdown of m6 A demethylase α-ketoglutarate-dependent dioxygenase alkB homolog 5 (ALKBH5) significantly enhanced circNRIP1 m6 A modification and upregulated its expression. These results show that ALKBH5 knockdown upregulates circNRIP1, thus promoting glycolysis in PTC cells. Therefore, circNRIP1 can be a prognostic biomarker and therapeutic target for PTC by acting as a sponge for oncogenic miR-541-5p and miR-3064-5p to upregulate PKM2 expression.

The retinoic acid receptor co-factor NRIP1 is uniquely upregulated and represents a therapeutic target in acute myeloid leukemia with chromosome 3q rearrangements.

Aberrant expression of Ecotropic Viral Integration Site 1 (EVI1) is a hallmark of acute myeloid leukemia (AML) with inv(3) or t(3;3), which is a disease subtype with especially poor outcome. In studying transcriptomes from AML patients with chromosome 3q rearrangements, we identified a significant upregulation of the Nuclear Receptor Interacting Protein 1 (NRIP1) as well as its adjacent non-coding RNA LOC101927745. Utilizing transcriptomic and epigenomic data from over 900 primary samples from patients as well as genetic and transcriptional engineering approaches, we have identified several mechanisms that can lead to upregulation of NRIP1 in AML. We hypothesize that the LOC101927745 transcription start site harbors a context-dependent enhancer that is bound by EVI1, causing upregulation of NRIP1 in AML with chromosome 3 abnormalities. Furthermore, we showed that NRIP1 knockdown negatively affects the proliferation and survival of 3qrearranged AML cells and increases their sensitivity to all-trans retinoic acid, suggesting that NRIP1 is relevant for the pathogenesis of inv(3)/t(3;3) AML and could serve as a novel therapeutic target in myeloid malignancies with 3q abnormalities.

NRIP1 is activated by C-JUN/C-FOS and activates the expression of PGR, ESR1 and CCND1 in luminal A breast cancer.

Using chip array assays, we identified differentially expressed genes via a comparison between luminal A breast cancer subtype and normal mammary ductal cells from healthy donors. In silico analysis confirmed by western blot and immunohistochemistry revealed that C-JUN and C-FOS transcription factors are activated in luminal A patients as potential upstream regulators of these differentially expressed genes. Using a chip-on-chip assay, we identified potential C-JUN and C-FOS targets. Among these genes, the NRIP1 gene was revealed to be targeted by C-JUN and C-FOS. This was confirmed after identification and validation with transfection assays specific binding of C-JUN and C-FOS at consensus binding sites. NRIP1 is not only upregulated in luminal A patients and cell lines but also regulates breast cancer-related genes, including PR, ESR1 and CCND1. These results were confirmed by NRIP1 siRNA knockdown and chip array assays, thus highlighting the putative role of NRIP1 in PGR, ESR1 and CCND1 transcriptional regulation and suggesting that NRIP1 could play an important role in breast cancer ductal cell initiation.

The Expression of NRIP1 and LCOR in Endometrioid Endometrial Cancer.

BACKGROUND: The aim of the study was to analyze the expression of nuclear receptor interacting protein 1 (NRIP1) and its partner ligand-dependent nuclear receptor co-repressor (LCOR) in endometrioid endometrial cancer and to investigate their association with estrogen receptor (ER), progesterone receptor (PR), Ki-67, clinicopathological parameters and patient survival. MATERIALS AND METHODS: Immunohistochemical evaluation was carried out to investigate the subcellular expression of NRIP1 and LCOR in endometrioid endometrial cancer samples. Statistical analysis was used to identify the correlations of NRIP1 and LCOR expression with clinicopathological variables and to estimate the survival rates. RESULTS: Endometrial cancer tissues exhibited higher expression of NRIP1 and LCOR in comparison with the normal tissues. Cytoplasmic LCOR expression was positively associated with ER and PR expression, while cytoplasmic NRIP1 expression was positively associated with ER expression. Moreover, cytoplasmic expression of NRIP1 was positively associated with Ki-67. CONCLUSION: Our study demonstrated that high cytoplasmic expression of LCOR may predict a longer overall survival of patients with endometrioid endometrial cancer. Patients with tumors expressing low levels of LCOR showed a worse survival compared to those expressing high levels.

Knockdown of circNRIP1 sensitizes colorectal cancer to 5­FU via sponging miR­532­3p.

The present study aimed to investigate the influence of circular RNA nuclear receptor­interacting protein 1 (circNRIP1) on the chemotherapeutic effect of 5­fluorouracil (5­FU) in colorectal cancer (CRC) and reveal its potential molecular mechanisms. The effects of circNRIP1 on cell proliferation, migration and invasion, and apoptosis were evaluated using Cell Counting Kit­8, Transwell and flow cytometric assays, respectively. A dual­luciferase reporter assay was performed to verify the potential interaction between circNRIP1 and microRNA (miR)­532­3p. The results of the present study indicated that circNRIP1 was upregulated in CRC and its increased expression was associated with CRC progression. Furthermore, overexpression of circNRIP1 promoted CRC cell proliferation, invasion and migration, while it inhibited apoptosis. Knockdown of circNRIP1 significantly enhanced the 5­FU­induced inhibition of the viability of HCT116 and SW480 cells. Bioinformatics analysis predicted that miR­532­3p was a direct target of circNRIP1, which was further confirmed by a dual­luciferase reporter assay. miR­532­3p silencing reversed the effects of circNRIP1 knockdown on the sensitivity of 5­FU in the chemotherapy of CRC. The results suggested that circNRIP1 and miR­532­3p may be utilized to improve the diagnosis of CRC and serve as diagnostic markers. In conclusion, overexpression of circNRIP1 promoted the progression of CRC, while circNRIP1 silencing sensitized CRC cells to 5­FU via sponging miR­532­3p.

Circular RNA circNTRK2 facilitates the progression of esophageal squamous cell carcinoma through up-regulating NRIP1 expression via miR-140-3p.

BACKGROUND: Esophageal squamous cell carcinoma (ESCC) is one of the most prevalent gastrointestinal malignancies with high mortality. Circular RNAs (CircRNAs) have become a research hotspot in recent years for their vital roles in cancer development and progression. This study aims to clarify the roles of circNTRK2 and its underlying molecular mechanisms in ESCC. METHODS: The levels of circNTRK2, miR-140-3p, and nuclear receptor-interacting protein 1 (NRIP1) mRNA were examined by qRT-PCR. The cell proliferation ability was detected via CCK-8, EdU and colony formation assays. The invasion capacity was tested by using transwell assay. The apoptotic rate was evaluated through flow cytometry. The protein levels of cleaved PARP, cleaved caspase-3, E-cadherin, vimentin, and NRIP1 were measured by western blot assay. The validation of circular structure was performed by Sanger sequencing, divergent primer PCR, and RNase R treatments. The ceRNA regulatory mechanism of circNTRK2 was observed via dual-luciferase reporter, RIP and RNA pull-down assays. The mice xenograft models were constructed to confirm the oncogenicity of circNTRK2 in ESCC in vivo. RESULTS: CircNTRK2 was highly expressed in ESCC tissues and cells. High expression of circNTRK2 was correlated with advanced TNM stage, lymph node metastasis and short survival. Knockdown of circNTRK2 inhibited ESCC cell proliferation, invasion and epithelial-mesenchymal transition (EMT), and accelerated apoptosis in vitro. Mechanistic assays disclosed that circNTRK2 could act as a sponge for miR-140-3p to abate its suppression on target NRIP1 expression. Moreover, miR-140-3p-induced inhibitory effects on ESCC cell malignant phenotypes were attenuated by the overexpression of circNTRK2. In addition, depletion of NRIP1 impeded cell proliferation, invasion and EMT, while enhanced apoptosis. Furthermore, silencing of circNTRK2 suppressed cell proliferation and invasion through regulating NRIP1 expression. Also, knockdown of circNTRK2 slowed ESCC tumor growth in vivo. CONCLUSION: CircNTRK2 promoted ESCC progression by regulating miR-140-3p/NRIP1 pathway. Our findings contribute to a better understanding of circRNAs as miRNA sponges and highlight a promising therapy target in ESCC.

Regulation of LCoR and RIP140 expression in cervical intraepithelial neoplasia and correlation with CIN progression and dedifferentiation.

PURPOSE: Ligand-dependent corepressor (LCoR) and receptor-interacting protein 140 (RIP140/NRIP1) play an important role in the regulation of multiple oncogenic signaling pathways and the development of cancer. LCoR and RIP140 form a nuclear complex in breast cancer cells and are of prognostic value in further prostate and cervical cancer. The purpose of this study was to analyze the regulation of these proteins in the development of cervical intraepithelial neoplasia (CIN I-III). METHODS: Immunohistochemical analysis was obtained to quantify RIP140 and LCoR expression in formalin-fixed paraffin embedded tissue sections of cervical intraepithelial neoplasia samples. Tissue (n = 94) was collected from patients treated in the Department of Gynecology and Obstetrics, Ludwig-Maximilians-University of Munich, Germany, between 2002 and 2014. Correlations of expression levels with clinical outcome were carried out to assess for prognostic relevance in patients with CIN2 progression. Kruskal-Wallis test and Mann-Whitney U test were used for data analysis. RESULTS: Nuclear LCoR overexpression correlates significantly with CIN II progression. Nuclear RIP140 expression significantly increases and nuclear LCoR expression decreases with higher grading of cervical intraepithelial neoplasia. Cytoplasmic RIP140 expression is significantly higher in CIN III than in CIN I or CIN II. CONCLUSION: A decrease of nuclear LCoR expression in line with an increase of dedifferentiation of CIN can be observed. Nuclear LCoR overexpression correlates with CIN II progression indicating a prognostic value of LCoR in cervical intraepithelial neoplasia. Nuclear and cytoplasmic RIP140 expression increases significantly with higher grading of cervical intraepithelial neoplasia underlining its potential role in the development of pre-cancerous lesions. These findings support the relevance of LCoR and RIP140 in the tumorigenesis indicating a possible role of LCoR and RIP140 as targets for novel therapeutic approaches in cervical intraepithelial neoplasia and cervical cancer.

The circular RNA-NRIP1 plays oncogenic roles by targeting microRNA-505 in the renal carcinoma cell lines.

We explored the roles and regulatory mechanisms of the circular RNA (circRNA) nuclear receptor-interacting protein 1 (NRIP1; circNRIP1) in ACHN and CAKI-1 cells. ACHN and CAKI-1 cells were transfected with small-interfering-circNRIP1 (si-circNRIP1) and microRNA-505 (miR-505) inhibitor or the corresponding controls. Cell viability was detected with the Cell Counting Kit-8. The protein expression levels of Bcl-2, Bax, cleaved-caspase-3, matrix metalloproteinase (MMP)-2, MMP-9, adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK), protein kinase B (AKT), phosphatidylinositol 3-kinase (PI3K), and mammalian target of rapamycin (mTOR) were individually determined via Western blot. Quantitative reverse transcription polymerase chain reaction was used to examine the expressions of circNRIP1 and miR-505 both in tumor cells and tissues. The apoptotic rate, the colony numbers, and the migration rate were separately determined by the Annexin V-fluorescein isothiocyanate/propidium iodide and flow cytometer, colony formation assay, and migration assay. We found that circNRIP1 was overexpressed in tumor tissue but miR-505 was overproduced. Silencing circZNF292 induced inhibition of cell viability, colony formation, and migration, as well as the activity of AMPK and PI3K/AKT/mTOR cascades but enhancement of apoptosis. si-circNRIP1 stimulated the upregulation of miR-505, whose silence abolished the effects of si-circNRIP1 on these elements mentioned above. In conclusion, the circNRIP1 played oncogenic roles in the ACHN and the CAKI-1 cell lines by targeting miR-505 via stimulating AMPK and PI3K/AKT/mTOR cascades.

Effect of glucose deprivation on the expression of genes encoding glucocorticoid receptor and some related factors in ERN1-knockdown U87 glioma cells.

OBJECTIVE: The aim of the present study was to examine the effect of glucose deprivation on the expression of genes encoded glucocorticoid receptor (NR3C1) and some related proteins (NR3C2, AHR, NRIP1, NNT, ARHGAP35, SGK1, and SGK3) in U87 glioma cells in response to inhibition of endoplasmic reticulum stress signaling mediated by ERN1/IRE1 (endoplasmic reticulum to nucleus signaling 1/inositol requiring enzyme 1) for evaluation of their possible significance in the control of glioma growth through endoplasmic reticulum stress signaling mediated by IRE1 and glucose deprivation. METHODS: The expression of NR3C1, NR3C2, AHR, NRIP1, NNT, ARHGAP35, SGK1, and SGK3 genes in U87 glioma cells transfected by empty vector pcDNA3.1 (control cells) and cells without ERN1 signaling enzyme function (transfected by dnERN1) under glucose deprivation was studied by real time quantitative polymerase chain reaction. RESULTS: It was shown that the expression level of NR3C2, AHR, SGK1, SGK3, and NNT genes was up-regulated in control U87 glioma cells under glucose deprivation condition in comparison with the control cells growing with glucose. At the same time, the expression of NRIP1 gene is down-regulated in these glioma cells under glucose deprivation, but NR3C1 and ARHGAP35 genes was resistant to this experimental condition. We also showed that inhibition of ERN1 signaling enzyme function significantly modified the response of most studied gene expressions to glucose deprivation condition. Thus, effect of glucose deprivation on the expression level of NR3C2, AHR, and SGK1 genes was significantly stronger in ERN1 knockdown U87 glioma cells since the expression of NNT gene was resistant to glucose deprivation condition. Moreover, the inhibition of ERN1 enzymatic activities in U87 glioma cells led to up-regulation of ARHGAP35 gene expression and significant down-regulation of the expression of SGK3 gene in response to glucose deprivation condition. CONCLUSIONS: Results of this study demonstrated that glucose deprivation did not change the expression level of NR3C1 gene but it significantly affected the expression of NR3C2, AHR, NRIP, SGK1, SGK3, and NNT genes in vector-transfected U87 glioma cells in gene specific manner and possibly contributed to the control of glioma growth since the expression of most studied genes in glucose deprivation condition was significantly dependent on the functional activity of IRE1 signaling enzyme.

Identification of new fusion genes and their clinical significance in endometrial cancer.

BACKGROUND: Fusion genes may play an important role in tumorigenesis, prognosis, and drug resistance; however, studies on fusion genes in endometrial cancer (EC) are rare. This study aimed to identify new fusion genes and to explore their clinical significance in EC. METHODS: A total of 28 patients diagnosed with EC were enrolled in this study. RNA sequencing was used to obtain entire genomes and transcriptomes. STAR-comparison and STAR-fusion prediction were applied to predict the fusion genes. Chi-square tests and Student t tests were used to verify the clinical significance with SPSS 13.0 software. RESULTS: New fusion genes were found, and the number of fusion genes varied from 3 to 110 among all patients with EC. The type of fusion genes varied and included messenger RNA (mRNA)-mRNA, long non-coding RNA (lncRNA)-lncRNA, and lncRNA-mRNA. There were six fusion genes with high fusion rates, namely, RP11-123O10.4-GRIP1, RP11-444D3.1-SOX5, RP11-680G10.1-GSE1, NRIP1-AF127936.7, RP11-96H19.1-RP11-446N19.1, and DPH7-PTP4A3. Further studies showed that these fusion genes are related to stage, grade, and recurrence, in which NRIP1-AF127936.7 and DPH7-PTP4A3 were found only in stage III patients with EC. DPH7-PTP4A3 was found in grades 2 and 3, and recurrent patients with EC. CONCLUSION: Fusion genes play an essential role in EC. Six genes that are overexpressed with high fusion rates are identified. NRIP1-AF127936.7 and DPH7-PTP4A3 might be related to stage, and DPH7-PTP4A3 be related to grade and recurrence.

Prognostic relevance of RIP140 and ERß expression in unifocal versus multifocal breast cancers: a preliminary report.

The aim of this study was to investigate the expression of two nuclear receptor transcriptional coregulators, namely RIP140 (receptor-interacting protein of 140 kDa) and LCoR (ligand-dependent corepressor) in unifocal versus multifocal breast cancers. The expression of these two proteins was analyzed by immunohistochemistry in a matched-pair cohort of 21 unifocal and 21 multifocal breast tumors. The expression of the two estrogen receptors (ERα and ERß) was studied in parallel. RIP140 and LCoR levels appeared lower in unifocal tumors compared to multifocal samples (decreased of immune-reactive scores and reduced number of high expressing cells). In both tumor types, RIP140 and LCoR expression was correlated with each other and with expression of ERß. Very interestingly, the expression of RIP140, LCoR, and ERß was inversely correlated with overall survival only for the unifocal group. The negative correlation with overall and recurrence free survival was more pronounced in patients whose unifocal tumors expressed high levels of both RIP140 and ERß. Altogether, this preliminary report indicates that the ERß/RIP140 signaling is altered in unifocal breast cancers and correlated with patient outcome. Further investigation is needed to decipher the molecular mechanisms and the biological relevance of this deregulation.

A peptide delivery system sneaks CRISPR into cells.

The CRISPR-Cas9 system has developed into a powerful platform for genome editing in various types of cells and tissues with single-nucleotide precision, but limited delivery options hamper its application in real-world settings. A new study by Shen et al. describes the use of an amphipathic peptide to deliver Cas9/sgRNA ribonucleoprotein complexes, leading to the disruption of GFP genes in cells and mice. Disruption of the Nrip1 gene in isolated pre-adipocytes led to a "browning" phenotype, pointing to new options in the fight against diabetes and obesity.

Evaluating the breast cancer predisposition role of rare variants in genes associated with low-penetrance breast cancer risk SNPs.

BACKGROUND: Genome-wide association studies (GWASs) have identified numerous single-nucleotide polymorphisms (SNPs) associated with small increases in breast cancer risk. Studies to date suggest that some SNPs alter the expression of the associated genes, which potentially mediates risk modification. On this basis, we hypothesised that some of these genes may be enriched for rare coding variants associated with a higher breast cancer risk. METHODS: The coding regions and exon-intron boundaries of 56 genes that have either been proposed by GWASs to be the regulatory targets of the SNPs and/or located < 500 kb from the risk SNPs were sequenced in index cases from 1043 familial breast cancer families that previously had negative test results for BRCA1 and BRCA2 mutations and 944 population-matched cancer-free control participants from an Australian population. Rare (minor allele frequency ≤ 0.001 in the Exome Aggregation Consortium and Exome Variant Server databases) loss-of-function (LoF) and missense variants were studied. RESULTS: LoF variants were rare in both the cases and control participants across all the candidate genes, with only 38 different LoF variants observed in a total of 39 carriers. For the majority of genes (n = 36), no LoF variants were detected in either the case or control cohorts. No individual gene showed a significant excess of LoF or missense variants in the cases compared with control participants. Among all candidate genes as a group, the total number of carriers with LoF variants was higher in the cases than in the control participants (26 cases and 13 control participants), as was the total number of carriers with missense variants (406 versus 353), but neither reached statistical significance (p = 0.077 and p = 0.512, respectively). The genes contributing most of the excess of LoF variants in the cases included TET2, NRIP1, RAD51B and SNX32 (12 cases versus 2 control participants), whereas ZNF283 and CASP8 contributed largely to the excess of missense variants (25 cases versus 8 control participants). CONCLUSIONS: Our data suggest that rare LoF and missense variants in genes associated with low-penetrance breast cancer risk SNPs may contribute some additional risk, but as a group these genes are unlikely to be major contributors to breast cancer heritability.

RIP140 in monocytes/macrophages regulates osteoclast differentiation and bone homeostasis.

Osteolytic bone diseases, such as osteoporosis, are characterized by diminished bone quality and increased fracture risk. The therapeutic challenge remains to maintain bone homeostasis with a balance between osteoclast-mediated resorption and osteoblast-mediated formation. Osteoclasts are formed by the fusion of monocyte/macrophage-derived precursors. Here we report, to our knowledge for the first time, that receptor-interacting protein 140 (RIP140) expression in osteoclast precursors and its protein regulation are crucial for osteoclast differentiation, activity, and coupled bone formation. In mice, monocyte/macrophage-specific knockdown of RIP140 (mϕRIP140KD) resulted in a cancellous osteopenic phenotype with significantly increased bone resorption and reduced bone formation. Osteoclast precursors isolated from mϕRIP140KD mice had significantly increased differentiation potential. Furthermore, conditioned media from mϕRIP140KD primary osteoclast cultures significantly suppressed osteoblast differentiation. This suppressive activity was effectively and rapidly terminated by specific Syk-stimulated RIP140 protein degradation. Mechanistic analysis revealed that RIP140 functions primarily by inhibiting osteoclast differentiation through forming a transcription-suppressor complex with testicular receptor 4 (TR4) to repress osteoclastogenic genes. These data reveal that monocyte/macrophage RIP140/TR4 complexes may serve as a critical transcription regulatory complex maintaining homeostasis of osteoclast differentiation, activity, and coupling with osteoblast formation. Accordingly, we propose a potentially novel therapeutic strategy, specifically targeting osteoclast precursor RIP140 protein in osteolytic bone diseases.