Requirement of the E2F3 Transcription Factor for BCR/ABL Leukemogenesis.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 33-33
Author(s):  
Anna M. Eiring ◽  
Paolo Neviani ◽  
Ramasamy Santhanam ◽  
Joshua J. Oaks ◽  
Ji Suk Chang ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Transcription Factor ◽  
Blast Crisis ◽  
Scid Mice ◽  
Myelogenous Leukemia ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Hnrnp A1 ◽  
Protein Levels ◽  
Abl Kinase

Abstract Several RNA binding proteins (RBPs) have been implicated in the progression of chronic myelogenous leukemia (CML) from the indolent chronic phase to the aggressively fatal blast crisis. In the latter phase, expression and function of specific RBPs are altered at transcriptional or post-translational levels by the increased constitutive kinase activity of the BCR/ABL oncoprotein, resulting in enhanced resistance to apoptotic stimuli, growth advantage and differentiation arrest of CD34+ CML blast crisis (CML-BC) progenitors. In the current study, we identified by RIP (RNA immunoprecipitation)-mediated microarray analysis that mRNA encoding the E2F3 transcription factor associates to the BCR/ABL-regulated RBP hnRNP A1. Moreover, RNA electrophoretic mobility shift and UV-crosslinking assays revealed that hnRNP A1 interacts with E2F3 mRNA through a binding site located in the 3’UTR of both human and mouse E2F3 mRNA. Accordingly, E2F3 protein levels were upregulated in BCR/ABL-transformed myeloid precursor cell lines compared to parental cells in a BCR/ABL-kinase- and hnRNP A1 shuttling-dependent manner. In fact, treatment of BCR/ABL-expressing myeloid precursors with the kinase inhibitor Imatinib (2mM, 24 hr) or introduction of a dominant-negative shuttling-deficient hnRNP A1 protein (NLS-A1) markedly reduced E2F3 protein and mRNA levels. Similarly, upregulation of BCR/ABL expression/activity in the doxycycline inducible TonB2.10 cell line resulted in increased E2F3 protein expression. BCR/ABL kinase-dependent induction of E2F3 protein levels was also detected in CML-BCCD34+ compared to CML-CPCD34+ progenitors from paired patient samples and to normal CD34+ bone marrow samples. Importantly, the in vitro clonogenic potential of primary mouse BCR/ABL+ lineage negative (Lin−) progenitors was markedly impaired in BCR/ABL+ E2F3−/− compared to BCR/ABL-transduced E2F3+/+ myeloid progenitors and upon shRNA-mediated downregulation of E2F3 expression (90% inhibition, P<0.001). Furthermore, subcutaneous injection of shE2F3-expressing BCR/ABL+ cells into SCID mice markedly impaired in vivo tumorigenesis (>80% reduction in tumor burden, P<0.01). Accordingly, BCR/ABL leukemogenesis was strongly inhibited in SCID mice intravenously injected with E2F3 shRNA-expressing 32D-BCR/ABL cells and in mice transplanted with BCR/ABL-transduced Lin− bone marrow cells from E2F3−/− mice. Specifically, we demonstrate that reduced or absent levels of E2F3 resulted in dramatically decreased numbers of circulating BCR/ABL+ cells as determined by nested RT-PCR at 4 weeks post-injection (P=0.0001), normal splenic architecture and bone marrow cellularity and the absence of infiltrating myeloid blasts into non-hematopoietic compartments (i.e. liver). By contrast, SCID mice transplanted with vector-transduced 32D-BCR/ABL cells or BCR/ABL+ E2F3+/+ Lin− BM progenitors showed signs of an overt acute leukemia-like process with blast infiltration of hematopoietic and non-hematopoietic organs. Altogether, these data outline the importance of E2F3 expression for BCR/ABL leukemogenesis and characterize a new potential therapeutic target for the treatment of patients with advanced phase CML.

scholarly journals Normal and leukemic SCID-repopulating cells (SRC) coexist in the bone marrow and peripheral blood from CML patients in chronic phase, whereas leukemic SRC are detected in blast crisis

Blood ◽  
1996 ◽  
Vol 87 (4) ◽  
pp. 1539-1548 ◽  
Author(s):  
C Sirard ◽  
T Lapidot ◽  
J Vormoor ◽  
JD Cashman ◽  
M Doedens ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Animal Model ◽  
Peripheral Blood ◽  
Blast Crisis ◽  
Chronic Phase ◽  
Human Cells ◽  
Scid Mice ◽  
Myelogenous Leukemia ◽  
Normal Cells ◽  
Starting Point

Progress in understanding the abnormal regulation of hematopoiesis in chronic myelogenous leukemia (CML) would be facilitated if neoplastic cells, at all stages of the disease, could be studied in an animal model. In this report, we show that irradiated severe combined immunodeficient (SCID) mice can be transplanted with both normal (Philadelphia chromosome [Ph]-negative) and neoplastic (Ph+) cells from CML patients with either chronic or blast phase disease. Mice transplanted with peripheral blood (PB) or bone marrow (BM) cells from 9 of 12 chronic phase CML patients were well engrafted with human cells including multilineage colony-forming progenitors and CD34+ cells for at least 90 days posttransplantation. Repeated posttransplant injections of cytokines did not enhance the number of engrafted human cells. Interestingly, approximately 70% of the human progenitors found in the engrafted SCID BM were Ph-, suggesting that the growth of primitive normal cells is favored in this in vivo transplant model. A similar number of normal cells were found in mice transplanted with either PB or BM cells, suggesting that elevated numbers of primitive normal cells are present in CML PB. When cells from patients with CML in either myeloid or lymphoid blast crisis were transplanted into SCID mice, the BM of these mice was more rapidly repopulated and to a higher level than that observed with transplants of chronic phase cells. Moreover, all human colony-forming progenitors present in the BM of mice transplanted with blast crisis cells were Ph+, and the majority of cells showed the same morphological features of the blast crisis cells originally transplanted. These experiments provide a starting point for the creation of an animal model of CML and establish the feasibility of using this model for the future characterization of transplantable CML stem cells during disease progression.

scholarly journals GFI1-Dependent SGPP1 Repression Promotes Growth and Survival of Myeloma Cells

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 4387-4387
Author(s):  
Daniela Nicoleta Petrusca ◽  
Evgeny Berdyshev ◽  
Colin D. Crean ◽  
Judith L Anderson ◽  
G. David Roodman
Keyword(s):  
Bone Marrow ◽  
Cell Growth ◽  
Cell Fate ◽  
Cell Lines ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Drug Resistant ◽  
Growth And Survival ◽  
Protein Levels ◽  
P53 Status

Multiple myeloma (MM) remains incurable for the vast majority of patients due to emergence of drug resistant clones and mutations inducing drug resistant relapses. This is despite the fact that new therapies have greatly improved progression-free and overall survival for patients with standard risk myeloma. We recently found that the transcriptional repressor GFI1 is increased in bone marrow stromal cells of MM patients (MM-BMSC) where it causes prolonged suppression of osteoblast differentiation, and in CD138+ cells from MM patients, where GFI1 levels significantly correlate with disease progression. We also found that GFI1 overexpression (o/e) enhances MM cell growth and partially confers resistance to proteasome inhibitors in vitro as well as enhances tumor growth and osteoclastogenesis in vivo. Although the mechanisms responsible for these GFI1 effects in p53wt MM cells were p53-dependent, we found that GFI1 is also essential for MM cell survival regardless of their p53 status. The p53-independent mechanisms responsible for Gfi1 effects on MM cells growth and survival of are unknown. Sphingolipids are bioactive lipids that can control MM cell growth and survival. The balance between the levels of Sphingosine-1-phosphate (S1P) and its metabolic precursors ceramide (Cer) and sphingosine (SPH) form a rheostat that determines whether a cell proliferates or dies. We hypothesized that GFI1 represses SGPP1, the enzyme responsible for degrading S1P via salvage and recycling of sphingosine into long-chain ceramides. This repression changes the intracellular sphingolipid profile (Cer/S1P/SPH ratio) to maintain c-Myc upregulation in a protein phosphatase 2 (PP2A)-dependent manner, thus promoting growth and survival of MM cells. To test this hypothesis we measured S1P, SPH and Cer levels by mass spectrometry (LC-MS/MS). LC-MS/MS evaluation showed that bone marrow plasma of MM patients has significant higher levels of S1P when compared to normal donors. Moreover, intracellular S1P levels of MM.1S GFI1 o/e cells were also significantly higher as compared to those of MM.1S empty vector controls. Knock-down (KD) of Gfi1 in MM.1S cells strikingly increased SGPP1 and decreased SphK1 (the enzyme which catalyzes S1P production) mRNA levels, while GFI1 o/e cells had the opposite effect. We found that CD138+ cells isolated from MM patients expressed elevated levels of SphK1 mRNA compared to MGUS patients, and that SphK1 protein levels directly correlate with GFI1 levels in MM patient CD138+ cells and cell lines (r= 0.527). We also detected an indirect correlation (r= -0.961) between GFI1 and SGPP1 mRNA levels in five different MM cell lines. These results indicate a GFI1-dependent imbalance of the enzymes regulating S1P production. Further, KD GFI1 and SphK1 inhibition (5 μM SK1I) had a profound inhibitory effect on c-Myc protein levels and induced caspase 3 activation as detected by Western blotting, while GFI1 o/e cells had significant higher levels of c-Myc and were more resistant to SK1I treatment. Exogenous ceramide (10 μM Cer 16:0) treatment or SphK1 inhibition (5 μM SK1I), both treatments known to trigger intracellular ceramide production, significantly inhibited MM cell viability (measured by AlamarBlue), regardless of their p53 status (MM1.S p53 +/+ and KMS-11 p53 -/-). This inhibition of MM viability was GFI1-dependent, as GFI1 o/e cells were significantly more resistant to ceramide-induced cell death, which was PP2A dependent, as PP2A inhibition with okadaic acid (OA) restored it. MM.1S cells with KD of GFI1 exhibited significantly higher PP2A activity then control cells, supporting our observation that c-Myc modulation by GFI1 is PP2A-dependent. c-Myc protein levels were significantly decreased in MM.1S control cells treated with ceramide and rescued by OA pre-treatment; thus mimicking the effects of changing GFI1 levels and I2PP2A (the PP2A endogenous inhibitor) and confirms that PP2A mediates the effects of GFI1 on c-Myc. Taken together, our results show that GFI1 acts as a key regulator of MM growth and survival, at least partially through modulation of SGPP1. Therefore, targeting lipid metabolism to modulate the levels of specific bioactive lipid components that can modify cancer cell fate may provide a new and attractive therapeutic approach for MM. Disclosures Roodman: Amgen: Membership on an entity's Board of Directors or advisory committees.

ZFP143 Activates C/EBPα Transcription in Myeloid Cells.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1233-1233
Author(s):  
Boris Bartholdy ◽  
David Gonzalez ◽  
Daniel G. Tenen
Keyword(s):  
Transcription Factor ◽  
Binding Site ◽  
Blast Crisis ◽  
Myeloid Cells ◽  
Gene Trap ◽  
Myelogenous Leukemia ◽  
Mrna Levels ◽  
Consensus Binding Site ◽  
Differentiation Block

Abstract C/EBPα is a key transcription factor involved in myeloid differentiation and frequently mutated or deregulated in human acute myeloid leukemias (AML) as well as in blast crisis of chronic myelogenous leukemia (CML). Disruption of its function contributes to the differentiation block observed in these diseases and thus to leukemogenesis. Here, we have identified a conserved region in the C/EBPα promoter that is important for activation of C/EBPα transcription in myeloid cells and narrowed it down to a conserved site of approximately 25 bp that contains a consensus binding site for ZFP143, a seven-zinc finger transcription factor. In gel retardation assays, this region bound a factor of approximately 100 kDa that we biochemically purified and identified by mass spectrometry as being indeed ZFP143. In vivo binding of ZFP143 to its bona fide binding site in the C/EBPα promoter was also detected by chromatin immunoprecipitation assays. We are now studying the in vivo effect of ZFP143 on C/EBPα transcription in mice that carry an inducible gene trap in the ZFP143 locus. While mice homozygous for the active gene trap - that prevents ZFP143 transcription - die at an early embryonic stage, preliminary data from heterozygous mice shows indeed a reduction of C/EBPα mRNA levels, suggesting a role for ZFP143 in C/EBPα transcription activation. Ongoing experiments aim at selectively inactivating ZFP143 in the hematopoietic system using the Mx1-Cre / loxP system.

scholarly journals A MAPK/HNRPK pathway controls BCR/ABL oncogenic potential by regulating MYC mRNA translation

Blood ◽  
2006 ◽  
Vol 107 (6) ◽  
pp. 2507-2516 ◽  
Author(s):  
Mario Notari ◽  
Paolo Neviani ◽  
Ramasamy Santhanam ◽  
Bradley W. Blaser ◽  
Ji-Suk Chang ◽  
...  
Keyword(s):  
Blast Crisis ◽  
Chronic Phase ◽  
Mrna Translation ◽  
Myelogenous Leukemia ◽  
Translation Regulation ◽  
Regulatory Function ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Entry Site

AbstractAltered mRNA translation is one of the effects exerted by the BCR/ABL oncoprotein in the blast crisis phase of chronic myelogenous leukemia (CML). Here, we report that in BCR/ABL+ cell lines and in patient-derived CML blast crisis mononuclear and CD34+ cells, p210BCR/ABL increases expression and activity of the transcriptional-inducer and translational-regulator heterogeneous nuclear ribonucleoprotein K (hnRNP K or HNRPK) in a dose- and kinase-dependent manner through the activation of the MAPKERK1/2 pathway. Furthermore, HNRPK down-regulation and interference with HNRPK translation-but not transcription-regulatory activity impairs cytokine-independent proliferation, clonogenic potential, and in vivo leukemogenic activity of BCR/ABL-expressing myeloid 32Dcl3 and/or primary CD34+ CML-BC patient cells. Mechanistically, we demonstrate that decreased internal ribosome entry site (IRES)-dependent Myc mRNA translation accounts for the phenotypic changes induced by inhibition of the BCR/ABL-ERK-dependent HNRPK translation-regulatory function. Accordingly, MYC protein but not mRNA levels are increased in the CD34+ fraction of patients with CML in accelerated and blastic phase but not in chronic phase CML patients and in the CD34+ fraction of marrow cells from healthy donors. Thus, BCR/ABL-dependent enhancement of HNRPK translation-regulation is important for BCR/ABL leukemogenesis and, perhaps, it might contribute to blast crisis transformation. (Blood. 2006;107:2507-2516)

scholarly journals Identification of novel posttranscriptional targets of the BCR/ABL oncoprotein by ribonomics: requirement of E2F3 for BCR/ABL leukemogenesis

Blood ◽  
2008 ◽  
Vol 111 (2) ◽  
pp. 816-828 ◽  
Author(s):  
Anna M. Eiring ◽  
Paolo Neviani ◽  
Ramasamy Santhanam ◽  
Joshua J. Oaks ◽  
Ji Suk Chang ◽  
...  
Keyword(s):  
Rna Binding ◽  
Bone Marrow Cells ◽  
Rna Binding Proteins ◽  
Blast Crisis ◽  
Chronic Phase ◽  
Myelogenous Leukemia ◽  
Dependent Manner ◽  
Hnrnp A1 ◽  
Altered Expression

Several RNA binding proteins (RBPs) have been implicated in the progression of chronic myelogenous leukemia (CML) from the indolent chronic phase to the aggressively fatal blast crisis. In the latter phase, expression and function of specific RBPs are aberrantly regulated at transcriptional or posttranslational levels by the constitutive kinase activity of the BCR/ABL oncoprotein. As a result, altered expression/function of RBPs leads to increased resistance to apoptotic stimuli, enhanced survival, growth advantage, and differentiation arrest of CD34+ progenitors from patients in CML blast crisis. Here, we identify the mRNAs bound to the hnRNP-A1, hnRNP-E2, hnRNP-K, and La/SSB RBPs in BCR/ABLtransformed myeloid cells. Interestingly, we found that the mRNA encoding the transcription factor E2F3 associates to hnRNP-A1 through a conserved binding site located in the E2F3 3′ untranslated region (UTR). E2F3 levels were up-regulated in CML-BCCD34+ in a BCR/ABL kinase– and hnRNP-A1 shuttling–dependent manner. Moreover, by using shRNA-mediated E2F3 knock-down and BCR/ABL-transduced lineage-negative bone marrow cells from E2F3+/+ and E2F3−/− mice, we show that E2F3 expression is important for BCR/ABL clonogenic activity and in vivo leukemogenic potential. Thus, the complexity of the mRNA/RBP network, together with the discovery of E2F3 as an hnRNP-A1–regulated factor, outlines the relevant role played by RBPs in posttranscriptional regulation of CML development and progression.

Enhanced Killing of Chronic Myelogenous Leukemia Cells by Rapamycin and Imatinib Is Associated with Differential Inhibition of 4E-BP1 and eIF4E Phosphorylation and Decreased Protein Expression by Non-Overlapping Mechanisms.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1993-1993 ◽  
Author(s):  
James C. Moore ◽  
Chi Ly ◽  
Halbur Luke ◽  
S. Tiong Ong
Keyword(s):  
Protein Expression ◽  
Kinase Activity ◽  
Therapeutic Targets ◽  
Mrna Translation ◽  
Protein Translation ◽  
Myelogenous Leukemia ◽  
Cyclin D3 ◽  
Dependent Manner ◽  
Protein Levels ◽  
Abl Kinase

Abstract The Bcr-abl tyrosine kinase is known to promote transformation by dysregulating gene transcription, but its role in dysregulating translation is less well documented. Our recent work has implicated the mammalian target of rapamycin (mTOR) signaling as a downstream target of Bcr-Abl, since we find that the mTOR effectors, 4E-BP1 and S6, are phosphorylated in a Bcr-Abl kinase-dependent manner (Ly et al., Cancer Research, 2003). Because mTOR is a central regulator of eukaryotic translation, and inhibitors of mTOR act synergistically with imatinib mesylate (imatinib) to kill CML cells, these results suggest that, like transcription, translation may be a general cellular process dysregulated by Bcr-Abl activity. If this were so, then components of the cellular apparatus co-opted by Bcr-Abl to increase translation would constitute rational therapeutic targets. These would include signaling pathways mediating increased translation, components of the cap-binding complex (eIF4E, eIF4GI, and eIF4A) that regulate cap-dependent mRNA translation, as well as proteins whose translation is increased by Bcr-Abl kinase activity. Here we identify eIF4E as well as cyclin D3 as potential therapeutic targets in CML. Since eIF4E is essential for cap-dependent translation, and increased translation parallels eIF4E phosphorylation at Ser209, we determined the status of eIF4E phosphorylation in murine hematopoietic Ba/F3 cells expressing Bcr-Abl (Ba/F3-Bcr-Abl), and its dependence on Bcr-Abl kinase activity. Using phosphospecific antibodies to eIF4E, we found that Bcr-Abl kinase activity was essential for phosphorylation of eIF4E at Ser209, but had no effects on total levels of the protein. In contrast, rapamycin had no effect on the degree of eIF4E phosphorylation, although it was able to inhibit phosphorylation of 4E-BP1 completely (unlike imatinib). By examining total mRNA and protein levels of known targets of Bcr-Abl, we determined that cyclin D3, but not cyclin D2, was post-transcriptionally regulated by Bcr-Abl. Metabolic labeling studies were also conducted in Ba/F3-Bcr-Abl cells treated with media alone, imatinib, rapamycin, or both. Our results demonstrated that translation of cyclin D3 protein is regulated by the mTOR kinase in Bcr-Abl-expressing cells, and that combined inhibition of mTOR and Bcr-Abl resulted in an additional decrease in protein levels. Together, these results demonstrate that Bcr-Abl promotes protein translation of specific genes via mTOR, and that the activity of both Bcr-Abl and mTOR kinases contribute to dysregulated protein expression via non-overlapping mechanisms in CML cells. Ongoing studies are being conducted to determine the role of both eIF4E and cyclin D3 in the pathogenesis of CML.

scholarly journals Ligand-dependent repression of the erythroid transcription factor GATA-1 by the estrogen receptor.

1995 ◽  
Vol 15 (6) ◽  
pp. 3147-3153 ◽  
Author(s):  
G A Blobel ◽  
C A Sieff ◽  
S H Orkin
Keyword(s):  
Bone Marrow ◽  
Estrogen Receptor ◽  
Transcription Factor ◽  
Progenitor Cells ◽  
Erythroid Cell ◽  
High Dose ◽  
Dependent Manner ◽  
Erythroid Progenitor ◽  
Erythroid Progenitor Cells

High-dose estrogen administration induces anemia in mammals. In chickens, estrogens stimulate outgrowth of bone marrow-derived erythroid progenitor cells and delay their maturation. This delay is associated with down-regulation of many erythroid cell-specific genes, including alpha- and beta-globin, band 3, band 4.1, and the erythroid cell-specific histone H5. We show here that estrogens also reduce the number of erythroid progenitor cells in primary human bone marrow cultures. To address potential mechanisms by which estrogens suppress erythropoiesis, we have examined their effects on GATA-1, an erythroid transcription factor that participates in the regulation of the majority of erythroid cell-specific genes and is necessary for full maturation of erythrocytes. We demonstrate that the transcriptional activity of GATA-1 is strongly repressed by the estrogen receptor (ER) in a ligand-dependent manner and that this repression is reversible in the presence of 4-hydroxytamoxifen. ER-mediated repression of GATA-1 activity occurs on an artificial promoter containing a single GATA-binding site, as well as in the context of an intact promoter which is normally regulated by GATA-1. GATA-1 and ER bind to each other in vitro in the absence of DNA. In coimmunoprecipitation experiments using transfected COS cells, GATA-1 and ER associate in a ligand-dependent manner. Mapping experiments indicate that GATA-1 and the ER form at least two contacts, which involve the finger region and the N-terminal activation domain of GATA-1. We speculate that estrogens exert effects on erythropoiesis by modulating GATA-1 activity through protein-protein interaction with the ER. Interference with GATA-binding proteins may be one mechanism by which steroid hormones modulate cellular differentiation.

Congenital Juvenile Chronic Myelogenous Leukemia: Case Report and Review

PEDIATRICS ◽  
1984 ◽  
Vol 73 (3) ◽  
pp. 324-326
Author(s):  
Reese H. Clark ◽  
Leslie L. Taylor ◽  
Robert J. Wells
Keyword(s):  
Bone Marrow ◽  
Case Report ◽  
Chronic Myelogenous Leukemia ◽  
Peripheral Blood ◽  
Blast Crisis ◽  
Myelogenous Leukemia ◽  
Juvenile Form

The case of a patient with ecchymosis, hepatomegaly, leukocytosis, thrombocytopenia, and anemia at birth is presented. Throughout his course, thrombocytopenia, anemia, and leukocytosis without a marked increase in the number of blast forms in either peripheral blood or bone marrow persisted until the patient developed a blast crisis shortly before his death at age 4 months. This patient is the youngest reported to have the juvenile form of chronic myelogenous leukemia and the first that in the present era can be considered congenital in origin.

scholarly journals Regulation of AMH by oocyte-specific growth factors in human primary cumulus cells

Reproduction ◽  
2017 ◽  
Vol 154 (6) ◽  
pp. 745-753 ◽  
Author(s):  
Scott Convissar ◽  
Marah Armouti ◽  
Michelle A Fierro ◽  
Nicola J Winston ◽  
Humberto Scoccia ◽  
...  
Keyword(s):  
Fold Increase ◽  
Cumulus Cells ◽  
Maximal Effect ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Protein Levels ◽  
Secreted Factors ◽  
Morphogenetic Protein ◽  
Growth Differentiation Factor 9 ◽  
Signaling Inhibitors

The regulation of AMH production by follicular cells is poorly understood. The purpose of this study was to determine the role of the oocyte-secreted factors, growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15), on AMH production in primary human cumulus cells. Cumulus cells from IVF patients were cultured with a combination of GDF9, BMP15, recombinant FSH and specific signaling inhibitors. Stimulation with GDF9 or BMP15 separately had no significant effect onAMHmRNA levels. In contrast, simultaneous stimulation with GDF9 and BMP15 (G + B) resulted in a significant increase inAMHmRNA expression. Increasing concentration of G + B (0.6, 2.5, 5 and 10 ng/mL) stimulated AMH in a dose-dependent manner, showing a maximal effect at 5 ng/mL. Western blot analyses revealed an average 16-fold increase in AMH protein levels in cells treated with G + B when compared to controls. FSH co-treatment decreased the stimulation of AMH expression by G + B. The stimulatory effect of G + B on the expression of AMH was significantly decreased by inhibitors of the SMAD2/3 signaling pathway. These findings show for the first time that AMH production is regulated by oocyte-secreted factors in primary human cumulus cells. Moreover, our novel findings establish that the combination of GDF9 + BMP15 potently stimulates AMH expression.

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