GPS2 promotes erythroid differentiation in K562 erythroleukemia cells primarily via NCOR1.

G protein pathway suppressor 2 (GPS2) has been shown to play a pivotal role in human and mouse definitive erythropoiesis in an EKLF-dependent manner. However, whether GPS2 affects human primitive erythropoiesis is still unknown. This study demonstrated that GPS2 positively regulates erythroid differentiation in K562 cells, which have a primitive erythroid phenotype. Overexpression of GPS2 promoted hemin-induced hemoglobin synthesis in K562 cells as assessed by the increased percentage of benzidine-positive cells and the deeper red coloration of the cell pellets. In contrast, knockdown of GPS2 inhibited hemin-induced erythroid differentiation of K562 cells. GPS2 overexpression also enhanced erythroid differentiation of K562 cells induced by cytosine arabinoside (Ara-C). GPS2 induced hemoglobin synthesis by increasing the expression of globin and ALAS2 genes, either under steady state or upon hemin treatment. Promotion of erythroid differentiation of K562 cells by GPS2 mainly relies on NCOR1, as knockdown of NCOR1 or lack of the NCOR1-binding domain of GPS2 potently diminished the promotive effect. Thus, our study revealed a previously unknown role of GPS2 in regulating human primitive erythropoiesis in K562 cells.

VPS37C facilitates erythroid differentiation by promoting EKLF stability.

The process of erythroid differentiation is orchestrated at the molecular level by a complex network of transcription factors. Erythroid Krüppel-like factor (EKLF/KLF1) is a master erythroid gene regulator that directly regulates most aspects of terminal erythroid differentiation. However, the underlying regulatory mechanisms of EKLF protein stability are still largely unknown. In this study, we identified Vacuolar protein sorting 37 C (VPS37C), a core subunit of the Endosomal sorting complex required for transport-I (ESCRT-I) complex, as an essential regulator of EKLF stability. Our study showed that VPS37C interacts with EKLF and prevents K48-linked polyubiquitination of EKLF and proteasome-mediated EKLF degradation, thus enhancing EKLF protein stability and transcriptional activity. VPS37C overexpression in murine erythroleukemia (MEL) cells promotes hexamethylene bisacetamide (HMBA)-induced erythroid differentiation manifested by up-regulating erythroid-specific EKLF target genes and increasing benzidine-positive cells. In contrast, VPS37C knockdown inhibits HMBA-induced MEL cell erythroid differentiation. Particularly, the restoration of EKLF expression in VPS37C-knockdown MEL cells reverses erythroid-specific gene expression and hemoglobin production. Collectively, our study demonstrated VPS37C is a novel regulator of EKLF ubiquitination and degradation, which plays a positive role in erythroid differentiation of MEL cells by enhancing EKLF protein stability.

Associations of MTHFR gene polymorphism with lipid metabolism and risk of cerebral infarction in the Northwest Han Chinese population.

Objective: Genetic variation in the methylenetetrahydrofolate reductase (MTHFR) gene may contribute to the development of cerebral infarction (CI); however, results have been inconsistent across studies with different populations, including studies of the Chinese population. The aim of this study was to analyze the effect of MTHFR gene polymorphism on serum lipid and homocysteine levels among patients with CI in the Northwest Chinese Han population. Patients and methods: A total of 521 CI patients and 524 non-CI controls were enrolled in the study. Polymerase chain reaction and hybridization were utilized to identify MTHFR gene polymorphisms. Multivariate logistic regression analysis was used to assess the associations of MTHFR gene polymorphism with risk of CI. Results: Frequencies of the TT genotype and the T allele were markedly higher among CI patients than among controls. After stratifying our data by sex and age, we determined that these differences in frequency of the TT genotype and the T allele were statistically significant among participants of two different age brackets and among men, but not among women (i.e., there were no statistically significant differences between female patients and female controls). CI patients and control participants with the CT or TT genotype had significantly higher homocysteine (Hcy) levels than those with the CC genotype. Among CI patients, CT/TT carriers showed significantly lower high-density lipoprotein cholesterol (HDL-C) and apolipoprotein A-I (ApoA-I) levels as compared with CC carriers, but there was no significant difference for control participants. Multivariable logistic regression analysis showed that drinking; smoking; diabetes mellitus; levels of Hcy, direct bilirubin (DB), indirect bilirubin (IB), ApoA-I, and total protein (TP); and TT genotype were significant independent risk factors for CI. Conclusions: The results suggested that the TT genotype of the MTHFR C677T gene polymorphism, which is associated with hyperhomocysteinemia (HHcy), might be of great clinical significance in the identification of new biomarkers for CI and in the development of individualized preventive and therapeutic strategies.

Apolipoprotein E Gene Polymorphism Effects on Lipid Metabolism and Risk of Cerebral Infarction in Northwest Han Chinese Population.

Background: The apolipoprotein E (ApoE) genetic variation may contribute to the development of Cerebral Infarction (CI). Serum lipid levels are known risk factors for CI, but the effect of the ApoE gene polymorphism on lipid metabolism remains unclear. This retrospective cohort study was designed to determine the role of ApoE genotypes in CI risk and the relationships between ApoE gene polymorphism and serum lipid levels among the population of northwest China. Patients and Methods: 517 CI patients and 517 non-CI controls were enrolled in the study. Polymerase chain reaction and hybridization were utilized to determine the ApoE gene polymorphisms. Results: The ε3/ε4 genotype and ε4 allele frequency were significantly higher in CI patients than in controls. When stratified by age and sex, statistically significant differences in the distribution and frequency of the ε3/ε4 genotype and ε4 allele were found between patients and controls. Compared to ε2 carriers, ε4 carriers had significantly lower ApoE levels and higher low-density lipoprotein cholesterol (LDL-C), ApoB and ApoB/ApoA-I levels in both two groups. Additionally, control participants with ε4 carriers had significantly higher levels of lipoprotein and total cholesterol (TC) levels than ε2 carriers, while CI patients with ε4 carriers had a significantly lower level of ApoA-I. After adjusting for other established risk factors, drinking, hypertension, lipoprotein, triglycerides (TG) and ε4 allele were significant independent risk factors for CI, which was shown to be associated with a nearly two-fold CI risk. Conclusion: This study demonstrated that ε4 allele is independent risk factors for CI among patients in Northwest China. ApoE polymorphism was associated with CI, which was partly mediated through blood lipids and may also be mediated through non-lipid pathways. These data might be of great clinical significance in individualized preventive and therapeutic strategies.

Antineoplastic agents in chemotherapy facilitating tumor growth and angiogenesis in the interval administrations.

AIMS: There is emerging evidence that antineoplastic agents and the cytotoxic effects on tumor tissues attenuate the benefits of chemotherapy due to tumor microenvironment changes. Nevertheless, the actual relationship between chemotherapy and recurrent tumors in which the genotypes differ from the original tumor after chemotherapy is unclear. MATERIALS AND METHODS: Bone marrow transplantation, flow cytometer, immune inhibition and immunofluorescence will be utilized to investigate the effect of antineoplastic agents on bone-marrow-derived cells (BMDCs) release and recruitment, and to explore the pathways and mechanisms of antineoplastic agents in promoting tumor growth. KEY FINDINGS: Tumor growth and angiogenesis were significantly enhanced in the mouse model after treatment with antineoplastic agents such as cyclophosphamide, 5-fluorouracil, or cisplatin, along with large increases in proangiogenic vascular endothelial growth factor receptor-2 (VEGFR2+), ß3+, CD11b+Gr-1+, and VEGFR2+ß3+ BMDCs in circulating blood. BMDC recruitment and VEGFR2 and ß3 mRNA transcription in tumor tissues were also enhanced by antineoplastic agents. Antineoplastic-agent-treated BMDCs markedly augmented tumor and endothelial cell proliferation, and ß3 mRNA transcription in endothelial cells (ECs). SIGNIFICANCE: The results suggested that antineoplastic-agent treatment augmented the tumor microenvironment by mobilizing proangiogenic BMDCs, enhancing BMDC recruitment and angiogenesis, and increasing BMDC-mediated tumor and EC functions. These results led to tumor growth and angiogenesis aggravation. It is paramount to elucidate the potential mechanism by which the cellular and molecular effects triggered by the antineoplastic agents attenuate the effects of cancer therapy, and thereafter to explore possible methods for improving tumor treatment efficacy.

Effect of Apolipoprotein E ε4 Allele on the Progression of Carotid Atherosclerosis Through Apolipoprotein Levels.

Background: The apolipoprotein E (ApoE) genetic variation may be involved in the development of Carotid Atherosclerosis (CAS) disease. So far, few data are available on the role of ApoE isoforms in CAS. The association between this ApoE genotype and CAS remains controversial. The aim of this study was to investigate ApoE gene polymorphism in relation to CAS and the relationships between ApoE gene polymorphism and plasma lipid levels in the ShaanXi Han populations. Patients and methods: The study group enrolled 399 CAS participants and 399 non-CAS controls. ApoE gene polymorphisms were determined by Polymerase chain reaction and hybridization. Results: The ε3/ε4 genotype and ε4 allele in patients with CAS were significantly higher than control participants. In stratified analyses by age and sex, the elevated risk conferred by ɛ4 allele was evident in adults under 60 years old, but not in adults over 60 years old, females and males. ε4 carriers had significantly elevated ApoB and ApoB/ApoA and decreased ApoE levels than ε2 carriers in CAS patients. After adjusting for confounding factors, hypertension, ApoA-I, low density lipoprotein cholesterol (LDL-C), triglycerides (TG) and ε4 allele were significant independent risk factor for CAS. ApoE-ε4 allele was associated with a nearly 1.5-fold increased risk of CAS. Conclusion: This study provides convincing evidence that ε4 allele, hypertension, ApoA-I, LDL-C and TG levels are independent risk factor for CAS in the ShaanXi Han populations. ApoE polymorphism was associated with CAS and this association was partly mediated through blood lipids. Also, the clinical use of genomic data may become useful in optimizing individual preventative and therapeutic strategies.

A novel hydrogen peroxide fluorescent probe for bioimaging detection and enables multiple redox cycles.

In this subject, a novel hydrogen peroxide (H2O2) fluorescent probe (MNG) was designed and developed using naphthalimide derivatives and selenomorpholine. In PBS buffer (10 mM, pH = 7.4, 1 %DMSO), the selenomorpholine on the probe is capable of qualitatively and quantitatively detecting (H2O2) at a small amount under a detection limit of 61 nM. The probe follows a mechanism that Se (Ⅱ) in selenomorpholine is transformed to Se (Ⅳ), thus changing the spectra of the probe MNG. It is noteworthy that MNG can continuously make a cyclic response to H2O2 and glutathione (GSH), so it can potentially achieve redox process imaging in vivo. Moreover, this subject verified the redox process of the probe's continuous redox response in the Gaussian 09 programme through simulation calculation and mass spectrometry. The probe exhibits high biocompatibility. Moreover, it can detect H2O2 in MCF-7 cells and Argentine Bloodfin.

Design, synthesis and properties of hydrogen peroxide fluorescent probe based on benzothiazole.

Abnormal intracellular hydrogen peroxide (H2O2) concentration is related to cancer, cardiovascular, cerebrovascular diseases and other diseases. A novel H2O2 fluorescent probe (BBS) was designed and synthesized. The fluorescence intensity shows good linear relationship with the concentration of H2O2 (0-40 µM), and the detection limit is 132 nM. The response mechanism of probe BBS was verified and analyzed by UV-Vis spectra, titration spectra and density functional theory (DFT) on Gaussian 09 programme. BBS can be used for bioimaging in living cells.

Apolipoprotein E Gene Polymorphism and Coronary Artery Disease Risk Among Patients in Northwest China.

PURPOSE: The association between apolipoprotein E (ApoE) gene polymorphisms and the risk of coronary artery disease (CAD) among different populations has been assessed in numerous previous studies, but the results remain inconclusive. The present study aimed to determine the role of ApoE genotypes in CAD risk and the interrelationships between lipid profiles and ApoE alleles and genotypes among the population of northwest China. PATIENTS AND METHODS: This study was performed on 308 patients with CAD and 308 control participants. ApoE gene polymorphism was analysed using the polymerase chain reaction and hybridization. RESULTS: The findings indicated that the frequencies of ε3/ε4 genotype and ε4 allele frequency were significantly higher in patients with CAD than in the control participants. ε2 carriers had significantly lower total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and triglycerides (TG) levels than did ε3 or ε4 carriers among the control participants. However, our study found no significant differences in plasma lipoprotein levels between ɛ2, ɛ3 and ɛ4 carriers in patients with CAD. Moreover, ε4 carriers had significantly higher ApoB, ApoB/ApoA-I levels and significantly lower ApoE levels in both patients with CAD and control participants. ε4 allele presence was associated with a nearly two-fold higher CAD risk. After adjusting for other established risk factors, ε4 allele was an independent risk factor for CAD. After stratified by age (≤ 60 years and >60 years), ε4 allele was indicated to increase the CAD risk 3.3-fold in elderly patients with CAD, but not in young patients with CAD. After stratified by sex, ε4 allele was not a risk factor in females and males patients with CAD. CONCLUSION: This study provides evidence that the ε4 allele, drinking, smoking, hypertension, and TG and ApoE levels are independent risk factor for CAD among patients in northwest China.

Pharmacological targeting of NLRP3 deubiquitination for treatment of NLRP3-associated inflammatory diseases.

Pharmacologically inhibiting nucleotide-binding domain and leucine-rich repeat-containing (NLR) family, pyrin domain-containing protein 3 (NLRP3) inflammasome activation results in potent therapeutic effects in a wide variety of preclinical inflammatory disease models. NLRP3 deubiquitination is essential for efficient NLRP3 inflammasome activity, but it remains unclear whether this process can be harnessed for therapeutic benefit. Here, we show that thiolutin (THL), an inhibitor of the JAB1/MPN/Mov34 (JAMM) domain-containing metalloprotease, blocks NLRP3 inflammasome activation by canonical, noncanonical, alternative, and transcription-independent pathways at nanomolar concentrations. In addition, THL potently inhibited the activation of multiple NLRP3 mutants linked with cryopyrin-associated periodic syndromes (CAPS). Treatment with THL alleviated NLRP3-related diseases in mouse models of lipopolysaccharide-induced sepsis, monosodium urate-induced peritonitis, experimental autoimmune encephalomyelitis, CAPS, and methionine-choline-deficient diet-induced nonalcoholic fatty liver disease. Mechanistic studies revealed that THL inhibits the BRCC3-containing isopeptidase complex (BRISC)-mediated NLRP3 deubiquitination and activation. In addition, we show that holomycin, a natural methyl derivative of THL, displays an even higher inhibitory activity against NLRP3 inflammasome than THL. Our study validates that posttranslational modification of NLRP3 can be pharmacologically targeted to prevent or treat NLRP3-associated inflammatory diseases. Future clinical development of derivatives of THL may provide new therapies for NLRP3-related diseases.

GPS2 promotes erythroid differentiation by control of the stability of EKLF protein.

Erythropoiesis is a complex multistage process that involves differentiation of early erythroid progenitors to enucleated mature red blood cells, in which lineage-specific transcription factors play essential roles. Erythroid Krüppel-like factor (EKLF/KLF1) is a pleiotropic erythroid transcription factor that is required for the proper maturation of the erythroid cells, whose expression and activation are tightly controlled in a temporal and differentiation stage-specific manner. Here, we uncover a novel role of G-protein pathway suppressor 2 (GPS2), a subunit of the nuclear receptor corepressor/silencing mediator of retinoic acid and thyroid hormone receptor corepressor complex, in erythrocyte differentiation. Our study demonstrates that knockdown of GPS2 significantly suppresses erythroid differentiation of human CD34+ cells cultured in vitro and xenotransplanted in nonobese diabetic/severe combined immunodeficiency/interleukin-2 receptor γ-chain null mice. Moreover, global deletion of GPS2 in mice causes impaired erythropoiesis in the fetal liver and leads to severe anemia. Flow cytometric analysis and Wright-Giemsa staining show a defective differentiation at late stages of erythropoiesis in Gps2-/- embryos. Mechanistically, GPS2 interacts with EKLF and prevents proteasome-mediated degradation of EKLF, thereby increasing EKLF stability and transcriptional activity. Moreover, we identify the amino acids 191-230 region in EKLF protein, responsible for GPS2 binding, that is highly conserved in mammals and essential for EKLF protein stability. Collectively, our study uncovers a previously unknown role of GPS2 as a posttranslational regulator that enhances the stability of EKLF protein and thereby promotes erythroid differentiation.

A novel fluorescent sensor for specific recognition of GSH based on the copper complex and its bioimaging in living cells.

Given the important role of biothiols in various physiological processes, there is a need to develop novel fluorescent sensors for detecting them. Herein, a novel "on-off-on" fluorescent sensor (E)-N'-((7-(diethylamino)-2-oxo-2H-chromen-3-yl)methylene)-6-((quinolin-8-yloxy)methyl)picolinohydrazide (PQC) was synthesized and its absorbance and fluorescence properties were characterized. The sensor PQC could form a stable complex and showed a significant fluorescence quenching response to Cu2+ with a quenching efficiency of approximately 100%, and the PQC-Cu2+ complex showed a fluorescence enhancement response to GSH with a higher recovery rate of above 80% in a CH3OH/HEPES (9:1 v/v, pH = 7.23) buffer system. Its detection limits were determined to be 0.17 µM for Cu2+ and 0.20 µM for GSH, and the binding stoichiometry of PQC-Cu2+ was determined to be 1: 1 by Job's plot method. Importantly, the sensor PQC can be used for filter paper strip tests and bioimaging in living cells.

A novel fluorescent chemosensor based on coumarin and quinolinyl-benzothiazole for sequential recognition of Cu2+ and PPi and its applicability in live cell imaging.

In this study, a highly selective fluorescent sensor (E)-2-((2-(benzo[d]thiazol-2-yl)quinolin-8-yl)oxy)-N'-((7-(diethylamino)-2-oxo-2H-chromen-3-yl)methylene)acetohydrazide (TQC) was synthesized from 2-methylquinolin-8-ol and 4-(diethylamino)-2-hydroxybenzaldehyde and its structure was characterized by 1H NMR, 13C NMR, ESI-HR-MS and density functional theory (DFT) calculation. Sensor TQC showed an obvious "on-off-on" fluorescence response to Cu2+ and PPi in a DMSO/HEPES (3:2 v/v, pH = 7.4) buffer system. The detection limits of sensor TQC were 0.06 µM to Cu2+ and 0.01 µM to PPi. In addition, sensor TQC showed a 1:1 binding stoichiometry to Cu2+ and TQC-Cu2+ complex showed a 2:1 binding stoichiometry to PPi. The optimum pH range of sensor TQC and TQC-Cu2+ was 3-8. Further studies demonstrated that sensor TQC could be made into test paper strips for the qualitative of Cu2+ and PPi and showed sequentially "on-off-on" fluorescent bio-imaging of Cu2+ and PPi in HeLa cells.

A simple fluorescent probe for detection of Ag+ and Cd2+ and its Cd2+ complex for sequential recognition of S2.

In this study, we designed and synthesized a simple probe 2-(8-((8-methoxyquinolin-2-yl)methoxy)quinolin-2-yl)benzo[d]thiazole (DQT) for detection of Ag+ and Cd2+ in a CH3OH/HEPES (9 : 1 v/v, pH = 7.30) buffer system. Its structure was characterized by NMR, ESI-HR-MS and DFT calculations, and its fluorescence performance was also investigated. Probe DQT showed fluorescence quenching in response to Ag+ and Cd2+ with low detection limits of 0.42 µM and 0.26 µM, respectively. Importantly, the complexation of the probe with Cd2+ resulted in a red shift from blue to green, making it possible to detect Ag+ and Cd2+ by the naked eye under an ultraviolet lamp. The DQT-Cd2+ complex could be used for sequential recognition of S2-. The recovery response could be repeated 3 times by alternate addition of Cd2+ and S2-. A filter paper strip test further demonstrated the potential of probe DQT as a convenient and rapid assay.

A BODIPY-Based Water-Soluble Fluorescent Probe for Naked Eye Detection of pH.

In this study, a BODIPY-based water-soluble fluorescent chemosensor BBP has been synthesized using BODIPY as the fluorescence group and quinoline as the recognition group. BBP can be used for naked eye detection of pH in complete aqueous solution and it shows high specificity in a wide range of cations. The pKa value is determined to be 2.94 and the fluorescence intensity is linearly related to pH in the range of 2.4-3.6.

Synthesis of Four Illudalane Sesquiterpenes Utilizing a One-Pot Diels-Alder/Oxidative Aromatization Sequence.

The concise, divergent total syntheses of four illudalane sesquiterpenes using an indanone as the key intermediate are reported. The key elements in these total syntheses, which involve only four to six operational steps, consist of a Suzuki cross-coupling and a one-pot Diels-Alder/oxidative aromatization reaction.

Protective effect of troxerutin and cerebroprotein hydrolysate injection on cerebral ischemia through inhibition of oxidative stress and promotion of angiogenesis in rats.

Brain ischemia, including cerebral ischemia and cerebrovascular ischemia, leads to poor oxygen supply or cerebral hypoxia, and causes brain tissue death or cerebral infarction/ischemic stroke. The troxerutin and cerebroprotein hydrolysate injection (TCHI), is widely applied in China to improve blood supply in ischemic brain tissues and to enhance neuroprotective effects in clinical practice. However, the benefits and detailed underlying mechanism elaborating the effectiveness of TCHI in cerebrovascular diseases require further investigation. Therefore, in the present study, experimental in vivo and in vitro models were employed to investigate the potential mechanisms of TCHI on cerebral ischemic injury. The results demonstrated that TCHI increased the lactate dehydrogenase levels in the brain homogenate and conversely decreased lactic acid levels. TCHI was further observed to significantly increase superoxide dismutase activity and decrease malondialdehyde levels in ischemic brain tissues. In addition, TCHI significantly induced vascular maturation processes, including proliferation, adhesion, migration and tube formation in cultured human umbilical vein endothelial cells. Additionally, TCHI significantly stimulated microvessel formation in the rat aortic ring and chick chorioallantoic membrane assays. Taken together, these results provided strong evidence that TCHI stimulated angiogenesis at multiple steps, and indicated that TCHI attenuated cerebral ischemic damage through the amelioration of oxidative stress and promotion of angiogenesis.

ABRO1 promotes NLRP3 inflammasome activation through regulation of NLRP3 deubiquitination.

Deubiquitination of NLRP3 has been suggested to contribute to inflammasome activation, but the roles and molecular mechanisms are still unclear. We here demonstrate that ABRO1, a subunit of the BRISC deubiquitinase complex, is necessary for optimal NLRP3-ASC complex formation, ASC oligomerization, caspase-1 activation, and IL-1ß and IL-18 production upon treatment with NLRP3 ligands after the priming step, indicating that efficient NLRP3 activation requires ABRO1. Moreover, we report that ABRO1 deficiency results in a remarkable attenuation in the syndrome severity of NLRP3-associated inflammatory diseases, including MSU- and Alum-induced peritonitis and LPS-induced sepsis in mice. Mechanistic studies reveal that LPS priming induces ABRO1 binding to NLRP3 in an S194 phosphorylation-dependent manner, subsequently recruiting the BRISC to remove K63-linked ubiquitin chains of NLRP3 upon stimulation with activators. Furthermore, deficiency of BRCC3, the catalytically active component of BRISC, displays similar phenotypes to ABRO1 knockout mice. Our findings reveal an ABRO1-mediated regulatory signaling system that controls activation of the NLRP3 inflammasome and provide novel potential targets for treating NLRP3-associated inflammatory diseases.

A chemosensor with a paddle structure based on a BODIPY chromophore for sequential recognition of Cu2+ and HSO3.

In this study, a highly selective chemosensor ML based on a BODIPY fluorescent chromophore was synthesized for sequential recognition of Cu2+ and HSO3 - in a CH3OH/H2O (99 : 1 v/v) system, which contained three recognition sites and its structure characterized by 1H NMR, 13C NMR and ESI-HR-MS. The sensor ML showed an obvious "on-off" fluorescence quenching response toward Cu2+ and the ML-Cu2+ complex showed an "off-on" fluorescence enhancement response toward HSO3 -. The detection limit of the sensor ML was 0.36 µM to Cu2+ and 1.4 µM to HSO3 -. In addition, the sensor ML showed a 1 : 3 binding stoichiometry to Cu2+ and the recovery rate of ML-Cu2+ complex identifying HSO3 - could be over 70%. Sensor ML showed remarkable detection ability in a pH range of 4-8.

Estrogen enhances tumor growth and angiogenesis indirectly via mediation of bone marrow­derived cells as well as directly through stimulation of tumor and endothelial cells.

Estradiol (E2) is a prime culprit for enhancing the progression of female hormone­related cancers. Bone marrow­derived cells (BMDCs) have been found to play a pivotal role in tumor growth. Estrogen receptors (ERs) are also found on certain subtypes of BMDCs, in addition to endothelial cells (ECs) and certain tumor cells. However, the role of BMDCs in E2­induced tumor biology is still unclear. Thus, the effects of E2 on ER­negative 4T1 breast cancer growth, the mobilization and recruitment of BMDCs, and interactions among BMDCs, ECs, and 4T1 cells were investigated. The results showed that E2 potentiated 4T1 tumor growth and angiogenesis in mice subjected to sham operation, ovariectomy (OVX), or OVX and E2 replacement treatment. E2 supplementation in mice with OVX upregulated the transcription of stromal cell­derived factor­1 (SDF­1) mRNA in tumor tissues and enhanced the recruitment of BMDCs into tumor tissues in vivo. E2 deficiency significantly decreased proangiogenic CXCR4+, ß3+, Sca­1+ and CXCR4+ß3+ BMDCs circulating in the peripheral blood. Cell­based system analyses showed that E2 augmented the transcription of ß3 mRNA in ECs, increased the adhesion of BMDCs to ECs. In addition, E2 enhanced the BMDC­induced EC proliferation and migration, the BMDC­induced 4T1 proliferation and the 4T1­stimulated EC proliferation in addition to enhancing the proliferation of tumor cells and the migration of ECs in vitro. Therefore, E2 enhanced the growth of breast tumors by stimulating tumor cells and ECs directly, as well as by increasing proangiogenic BMDC mobilization and recruitment leading to augmentation of the tumor and EC functions indirectly by cell proliferation assay. These findings reveal a separate mechanism via which E2 promotes the growth of female hormone­dependent tumors, which may be useful in explorations of new therapies for related cancers.