scholarly journals Cell cycle commitment of rat muscle satellite cells.

1990 ◽  
Vol 111 (1) ◽  
pp. 201-207 ◽  
Author(s):  
R Bischoff
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Satellite Cells ◽  
Cell Number ◽  
Continuous Exposure ◽  
Serum Factors ◽  
Muscle Extract ◽  
Myogenic Stem Cells

Satellite cells of adult muscle are quiescent myogenic stem cells that can be induced to enter the cell cycle by an extract of crushed muscle (Bischoff, R. 1986. Dev. Biol. 115:140-147). Here, evidence is presented that the extract acts transiently to commit cells to enter the cell cycle. Satellite cells associated with both live and killed rat myofibers in culture were briefly exposed to muscle extract and the increase in cell number was determined at 48 h in vitro, before the onset of fusion. An 8-12-h exposure to extract with killed, but not live, myofibers was sufficient to produce maximum proliferation of satellite cells. Continuous exposure for over 40 h was needed to sustain proliferation of satellite cells on live myofibers. The role of serum factors was also studied. Neither serum nor muscle extract alone was able to induce proliferation of satellite cells. In the presence of muscle extract, however, satellite cell proliferation was directly proportional to the concentration of serum in the medium. These results suggest that mitogens released from crushed muscle produce long-lasting effects that commit quiescent satellite cells to divide, whereas serum factors are needed to maintain progression through the cell cycle. Contact with a viable myofiber modulates the response of satellite cells to growth factors.

The Potential Oncogenic and MLN4924-Resistant Effects of CSN5 on Cervical Cancer Cells

2021 ◽  
Author(s):  
Huilin Zhang ◽  
Ping He ◽  
Qing Zhou ◽  
Yan Lu ◽  
Bingjian Lu
Keyword(s):  
Cell Cycle ◽  
Cervical Cancer ◽  
Cell Proliferation ◽  
Cancer Cells ◽  
Cancer Cell ◽  
Cervical Cancer Cell ◽  
Cervical Cancers ◽  
Cervical Cancer Cells

Abstract BackgroundsCSN5, a member of Cop9 signalosome, is essential for protein neddylation. It has been supposed to serve as an oncogene in some cancers. However, the role of CSN5 has not been investigated in cervical cancer yet.MethodsData from TCGA cohorts and GEO dataset was analyzed to examine the expression profile of CSN5 in cervical cancers. The role of CSN5 on cervical cancer cell proliferation was investigated in cervical cancer cell lines, Siha and Hela, through CSN5 knockdown via CRISPR-CAS9. Western blot was used to detect the effect of CSN5 knockdown and overexpression. CCK8, clone formation assay and cell cycle assay were also employed. Besides, the role CSN5 knockdown in vivo was evaluated by xenograft tumor model. Moreover, MLN4924 was applied in Siha and Hela with CSN5 overexpression.ResultsWe found that downregulation of CSN5 in Siha and Hela cells inhibited cell proliferation in vitro and in vivo, and the inhibitory effects were largely rescued by CSN5 overexpression. Moreover, deletion of CSN5 caused cell cycle arrest rather than inducing apoptosis. Importantly, CSN5 overexpression confers resistance to the anti-cancer effects of MLN4924 (pevonedistat) in cervical cancer cells.ConclusionsOur findings demonstrated that CSN5 functions as an oncogene in cervical cancers and may serve as a potential indicator for predicting the effects of MLN4924 treatment in the future.

scholarly journals The role of IGF1 on the differentiation of prolactin secreting cells in the mouse anterior pituitary

2009 ◽  
Vol 203 (2) ◽  
pp. 231-240 ◽  
Author(s):  
Tamiki Hikake ◽  
Shinji Hayashi ◽  
Taisen Iguchi ◽  
Tomomi Sato
Keyword(s):  
Cell Proliferation ◽  
Progenitor Cells ◽  
Anterior Pituitary ◽  
Cell Number ◽  
Postnatal Period ◽  
Gh Cells ◽  
Cell Proliferation And Differentiation ◽  
Proliferation And Differentiation

IGF1 knockout (IGF1KO) mice show a reduced number of prolactin (PRL) producing cells (PRL cells); however, the role of IGF1 in PRL cell proliferation and differentiation in immature mice is unclear. In this study, ontogenic changes in the percentages of PRL cells, GH producing cells (GH cells), and 5-bromo-2′-deoxyuridine (BrdU)-labeled cells in the anterior pituitary of male IGF1KO mice during the postnatal period were investigated. The percentage of PRL cells in IGF1KO mice was significantly lower at day 20 compared with that in wild-type (WT) mice, while GH cells in IGF1KO mice were significantly increased from day 10. From days 5 to 20, the percentage of BrdU-labeled cells in WT and IGF1KO mice was similar. PRL cells and GH cells are thought to originate from the same progenitor cells, therefore, PRL cells in IGF1KO mice are not able to differentiate because progenitor cells have already committed to be GH cells. However, IGF1, 17β-estradiol (E2), epidermal growth factor (EGF), or IGF1 plus E2 treatments increased the PRL cell number in the pituitaries in vitro of 10-day-old WT and IGF1KO mice. This fact suggests that these factors are involved in PRL cell proliferation and differentiation. In addition, the increase of PRL cells in IGF1KO mice stimulated by E2 or EGF was less than that of WT mice. Thus, IGF1 plays a crucial role in PRL cell proliferation and differentiation in mouse pituitaries by regulating the differentiation of progenitor cells and mediating the actions of E2 and EGF.

scholarly journals Glaucocalyxin A suppresses multiple myeloma progression in vitro and in vivo through inhibiting the activation of STAT3 signaling pathway

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Mei Li ◽  
Cailong Chen ◽  
Qian Wang ◽  
Xiaolu Jiang ◽  
Lanlan Tan ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Multiple Myeloma ◽  
Cell Proliferation ◽  
Xenograft Model ◽  
Mice Model ◽  
Cycle Arrest ◽  
Nude Mice Model

Abstract Background Multiple myeloma (MM) is the most common malignant hematological disease in the people worldwide. Glaucocalyxin A (GLA) is a bioactive ent-kauranoid diterpenoid, that is derived from Rabdosia japonica var. GLA has been demonstrated that it had various pharmacological activities, such as anti-coagulation, anti-bacterial, anti-tumor, anti-inflammation, antioxidant activities. Although GLA has effective anti-tumor properties, its effects on multiple myeloma remain unclear. The aim of this study was to examine the possible anti-cancer effects of GLA and their molecular mechanisms on MM cells in vitro and in vivo. Methods To evaluate the role of GLA on the proliferation of MM cells in vitro and in vivo, we used MTT method to detect the role of GLA on the proliferation of MM cells. Cell apoptosis and cell cycle assay were evaluated by flow cytometry. Protein expressions in GLA-treated and untreated MM cells were evaluated by western blot analyses. MM xenograft nude mice model was used to investigate the role of GLA on the proliferation of MM cells in vivo. IHC assay was used to examine the role of GLA on the MM xenograft model in vivo. Results In the present study, we firstly reported the potent anti-myeloma activity of GLA on MM cells. We found that GLA could induce apoptosis in vitro and in vivo. GLA could inhibit the phosphorylation of the signal transducer and activator of transcription 3 (STAT3) and downregulate interleukin IL-6 induced STAT3 phosphorylation in MM. Overexpression of STAT3 could significantly prevent apoptosis induced by GLA; while knockdown of STAT3 enhanced it. Moreover, GLA could inhibit cell proliferation by inducing the cell cycle arrest. GLA reduced the expression of cell cycle-related proteins CCNB1, CCND1, CCND2, and CCND3 and increased the expression of p21 in MM cell lines. In addition, in the MM xenograft nude mice model, GLA exhibited very good anti-myeloma activity. Administration of GLA almost completely inhibited tumor growth within 19 days without physical toxicity. And the IHC results showed GLA significantly inhibited cell proliferation and interfered STAT3 pathway on MM xenograft model tumor tissues. Conclusions Taken together, our present research indicated that GLA inhibits the MM cell proliferation, induces MM cell apoptosis and cell cycle arrest through blocking the activation of STAT3 pathway. Thus, GLA may be a potential therapeutic candidate for MM patients in the future.

Role of Different C/EBPα Mutations in AML Transformation.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1343-1343
Author(s):  
Oscar Quintana-Bustamante ◽  
S. Lan-Lan Smith ◽  
Jude Fitzgibbon ◽  
Dominique Bonnet
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Cell Cycle Arrest ◽  
Myeloid Differentiation ◽  
Granulocytic Differentiation ◽  
Self Renewal ◽  
Cycle Arrest

Abstract Acute Myeloid Leukemia (AML) is characterized by an abnormal hematopoietic differentiation and uncontrolled cell proliferation. Mutations in several transcription factors (TFs) have been implicated in the development of leukemia. One of these TFs is CCAAT/enhancer-binding protein-α (C/EBPα). In normal hematopoiesis, C/EBPα plays a central role to coordinate myeloid differentiation and growth arrest. C/EBPα is mutated in approximately 9% of AML; these mutations take place either in C or N terminal domains of the protein, although there are several familial cases of AML where both types of mutations have been found. We use C and/or N terminal C/EBPα mutations from one case of sporadic AML to investigate the role of each mutation in leukemic transformation (Smith et al., 2004, N Engl J Med 351, 2403–2407). Human lineage negative (Lin-) umbilical cord blood were transduced with lentiviral vectors carrying the wild type C/EBPα (WT), N terminal mutated C/EBPα (N-ter) or N and C terminal mutated (NC-ter) C/EBPα cloned from this sporadic case of AML. We observed differences in proliferation of transduced Lin- in vitro: WT C/EBPα expression resulted in G0 cell cycle arrest causing a progressive extinction of the transduced cells overtime; N-ter cells showed a higher proliferative advantage over untransduced cells. The NC-ter CEBPα cells like untransduced cells kept their levels throughout culture. Furthermore, when induced into myeloid differentiation in vitro, WT C/EBPα cells were mainly inducing fully mature granulocytes whereas N-ter C/EBPα was not able to induce terminal granulocytic differentiation; in contrast NC-ter C/EBPα did not increase myeloid differentiation. Additionally, their ability to form Colony Forming Units (CFUs) in primary, secondary and tertiary replating was also tested: WT transduced cells gave rise to few primary CFUs; contrary, N and NC-ter could generate both primary and secondary CFUs, but only NC-ter cells were able to produce CFUs in tertiary replating, indicating its ability to maintain undifferentiated hematopoietic progenitors in vitro. These results were confirmed using Long-Term Culture Initiating Cells (LTC-IC) where the NC-ter mutated cells showed the highest LTC-IC after 5 weeks. Finally, in vivo transplantation in NOD/SCID/β2mnull indicated that NC-ter mutated cells engraft better than WT and N-ter 8 week post- transplant. Serial transplantation experiments are underway to evaluate their self-renewal capacity. Our results confirmed some known functions of WT C/EBPα in human hematopoiesis, such as inducing myeloid differentiation and cell cycle arrest. On the other hand, we showed new functions for the C/EBPα mutants. The N-ter C/EBPα mutation caused an increase in cell proliferation and blockage of terminal granulocytic differentiation, whereas the NC-ter C/EBPα mutation increased the self-renewal capacity of progenitor/stem cells without having an influence on myeloid differentiation. This work provides further insight into the mechanisms by which different C/EBPα mutations induce AML.

The RNA Binding Protein Musashi 2 Is up-Regulated in the Proliferative B-Cell Fraction of Chronic Lymphocytic Leukemia Clones

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 4149-4149
Author(s):  
Florencia Palacios ◽  
Xiao-Jie Yan ◽  
Jaqueline C. Barrientos ◽  
Jonathan E. Kolitz ◽  
Steven L. Allen ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Cell Division ◽  
B Cells ◽  
B Cell ◽  
Lymphocytic Leukemia ◽  
Ki 67 ◽  
Post Transcriptional Regulation

Abstract Chronic Lymphocytic Leukemia (CLL) is an incurable disease in which most of the tumor cells in the blood are arrested in G0/G1 stages of the cell cycle with only a minimal number displaying proliferative activity. In this regard, our group has found by gene expression profiling (GEP) that the proliferative fraction (PF) of CLL cells is enriched in the intraclonal subset marked by CXCR4dim CD5brite expression. Indeed, this subset differs by more than 1000 genes from the CXCR4brite CD5dim resting fraction (RF). The genes over-expressed in the PF relate to replication and migration as well as regulation of gene expression. One of these genes is Musashi 2 (MSI2). Of note, MSI2 is expressed at the highest levels in IGHV unmutated CLL (U-CLL) clones and their PFs. Normally, MSI2 binds mRNA and blocks translation of proteins, playing an important role in post-transcriptional regulation. In addition, MSI2 has been linked to proliferation of normal and malignant stem cells, tumorigenesis, and poor prognosis. In CLL, high MSI2 mRNA expression has been identified in patients with worse prognosis. Nevertheless, nothing is known about the function of MSI2 in CLL cells. Therefore, we have begun to study the biological role of MSI2 in B-CLL cells and its possible association with B-cell proliferation and CLL disease progression. Fist, we studied MSI2 protein expression by flow cytometry in CD19+ B cells from healthy donors (HD) and CD5+CD19+ cells from CLL patients, observing an up-regulation in CLL compared to HD. Also, we documented higher MSI2 expression in U-CLL compared to IGHV-mutated (M-CLL) CLL as well as HD. Within the leukemic clone, we observed that MSI2 expression was highest in the PF, lower in the intermediate (INT) fraction (defined as CXCR4int CD5int), and much lower in the RF (PF>INT>RF). The PF expressed 40% more MSI2 than the RF, suggesting that the highest amounts of MSI2 protein is in dividing and recently-divided cells of the clone. Since CLL B-cell proliferation occurs in the microenvironment of lymphoid organs, presumably delivered by external signals, we tested whether such signals could stimulate MSI2 expression. After stimulating CLL cells with TLR9 agonist + IL15 + IL2 in vitro MSI2 protein was up-regulated form 0.3 to 2.5 fold. In addition, the increase in MSI2 protein was associated with an enhancement in Ki-67+ cells and in phosphorylation of MAPK/ERK and AKT signaling components, measured by flow cytometry. These results suggest that signals from the microenvironment that induce cell growth and proliferation lead to MSI2 synthesis in CLL B cells. In order to study a possible association between MSI2 expression and cell division, we labeled CLL PBMCs with a dilutable cell tracer, CFSE, and then stimulated them in vitro with TLR9 agonist + IL15 + IL2. These studies indicated that MSI2 protein synthesis was increased in the activated cells and that MSI2 protein levels increased with each cell division. However, it was also clear that this increase was not directly associated to the extent of cell replication as CLL B cells from only 10% of the patients underwent 4 cycles of cell division. Since we observed an increase in MSI2 and Ki-67 expression after stimulation in all patients' clones but did not detect replication of CLL cells in all patients, we studied the effects of in vitro stimulation on cell cycle entry and completion and how this related to MSI2 expression. Experiments using propidium iodide to evaluate DNA content of PBMCs showed that in vitro stimulation increased the percentage of cells in S phase (5-25%) compared to control cells without activation (<5%), whereas only a small fraction of cells entered the M/G2 phases, with or without activation (<1% and <0.5%, respectably) suggesting that only a small portion of the cells completed the cell cycle and divided. Hence, MSI2 synthesis corresponds with DNA replication and not cell division, suggesting that MSI2 could be an important molecule involved in entry into and/or in the early phases of the cell cycle. These results, and the facts that MSI2 plays an important role in post-transcriptional regulation and is associated with cell proliferation and poor prognosis in cancer, suggest that a better understanding of the role of MSI2 in CLL patients will provide clues to understanding the birth and growth of CLL B cells and to identifying and designing new therapeutic strategies for the disease. Disclosures No relevant conflicts of interest to declare.

scholarly journals E2F1/2/7/8 as independent indicators of survival in patients with cervical squamous cell carcinoma

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Chang Yang ◽  
Zhao-Cong Zhang ◽  
Tian -Bo Liu ◽  
Ye Xu ◽  
Bai-Rong Xia ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cervical Cancer ◽  
Cell Proliferation ◽  
Transcription Factors ◽  
Prognostic Factors ◽  
Cancer Cells ◽  
In Vitro Experiments ◽  
Cervical Cancer Cells

Abstract Background Cervical cancer is the second leading cause of death in women 20–39 years old. Because coverage for cervical cancer screening is low, and the vaccination rate of human papillomavirus (HPV) is poor in some countries, potential markers to detect the disease at early stages are needed. E2F transcription factors (E2Fs) are a family of transcription factors that function in cell proliferation, differentiation, apoptosis, and tumorigenesis. As abnormal activation and regulation of E2Fs are related to tumor development and poor prognosis, we performed bioinformatic analyses and in vitro assays to evaluate the role of E2Fs in cervical cancer. Methods Transcriptional expression of E2Fs was initially evaluated in silico using ONCOMINE and Gene Expression Profiling Interactive Analysis (GEPIA), followed by evaluation of E2F1/2/7/8 protein levels using immunohistochemistry in 88 patient tissues. E2F2 and E2F7 mRNA levels were measured by RT-qPCR. LinkedOmics and Metascape were used to predict functions of E2Fs, and in vitro experiments were performed to assess the tumorigenic role of E2F2 and E2F7. Results In silico analysis showed that E2F1/2/7/8 were significantly overexpressed in cervical cancer, findings which were confirmed at the protein level using immunohistochemistry. Further, upregulation of E2F1/2/7/8 was associated with different clinicopathological prognostic factors, including positivity for lymph vessel invasion and deep invasion of cervical stroma. Increased expression of E2F1/2/7/8 was also related to shorter overall survival (OS) and disease-free survival (DFS) in patients with cervical cancer. Using multivariate analysis, we confirmed E2F1/2/7/8 as independent prognostic factors for shorter OS of patients with cervical cancer. Finally, in vitro experiments showed that E2F2 and E2F7 are involved in cell proliferation and migration and cell cycle regulation in both HPV-positive and HPV-negative cervical cancer cells. Conclusions E2F1/2/7/8 may be prognostic biomarkers for survival of patients with cervical cancer. E2F2 and E2F7 are involved in cell proliferation, migration, and cell cycle in both HPV-positive and HPV-negative cervical cancer cells.

scholarly journals The NLRP3/eIF2 axis drives cell cycle progression in acute myeloid leukemia

2021 ◽  
Author(s):  
Michela Luciano ◽  
Constantin Blöchl ◽  
Julia Vetter ◽  
Laura Urwanisch ◽  
Theresa Neuper ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Nlrp3 Inflammasome ◽  
Cell Cycle Progression ◽  
Mononuclear Cells ◽  
Inflammasome Activation ◽  
Cycle Progression ◽  
Eif2α Phosphorylation

Aberrant activation of the NLR family pyrin domain containing 3 (NLRP3) inflammasome mediates numerous inflammatory diseases. Oncogenes can activate the NLRP3 inflammasome and thereby promote myeloproliferative neoplasia, suggesting a crucial role of NLRP3 in the malignant transformation of hematopoietic cells. Here, we show that bone marrow-derived mononuclear cells of AML patients display enhanced expression of NLRP3, IL-1β; and IL-18 and that high-level expression of NLRP3 is linked to poor survival of AML patients. Pharmacological and genetic inhibition of NLRP3 inflammasome activation attenuated cell proliferation of MOLM-13 AML cells in vitro. In vivo, genetic inhibition of NLRP3 in MOLM-13 AML cells resulted in reduced engraftment potential in xenografts, along with reduced splenomegaly and organ infiltration. Differential proteomic analysis revealed the eIF2 pathway as potential target of NLRP3 in AML, with a significant increase of eIF2α; phosphorylation upon NLRP3 inhibition. NLRP3 inhibition also caused a strong decrease in cyclin - dependent kinases CDK4 and CDK6, accompanied by an upregulation of the CDK inhibitor p21 (CDKN1A) and a marked arrest of cell cycle progression in the G0/G1 phase, consistent with the role of eIF2α; phosphorylation as negative cell cycle regulator. Taken together, we show that inhibition of the NLRP3 inflammasome reduces AML cell proliferation by promoting eIF2α; phosphorylation, which in turn enhances the expression of cell cycle arrest genes such as p21. Thus, the study uncovers the NLRP3/eIF2 axis as new driver of AML proliferation and proposes a novel therapeutic treatment of AML by targeted inhibition of NLRP3 activation.

scholarly journals SCUBE3 downregulation modulates hepatocellular carcinoma by inhibiting CCNE1 via TGFβ/PI3K/AKT/GSK3β pathway

2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Pan Xu ◽  
Aoran Luo ◽  
Chuan Xiong ◽  
Hong Ren ◽  
Liang Yan ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Cell Cycle ◽  
Cell Proliferation ◽  
Cell Lines ◽  
Signalling Pathway ◽  
Cell Counting ◽  
Pathway Enrichment Analysis

Abstract Objectives We aimed to verify the role of signal peptide-CUB-EGF-like domain-containing protein3 (SCUBE3) in the hepatocellular carcinoma (HCC) progression. Methods The role of SCUBE3 in HCC cell proliferation, apoptosis, and cell cycle in vitro were detected using MTT assay, colony formation assay, 5-ethynyl-2´-deoxyuridine assay (EDU), Celigo cell counting assay, Caspase3/7 activity assay, and flow cytometry. The effect of SCUBE3 on HCC cell proliferation in vivo was inspected by a xenograft tumour model in nude mice. The related mechanisms were further studied. Results The level of SCUBE3 was upregulated in HCC tissues and cell lines. Knockdown of SCUBE3 inhibited proliferation, promoted apoptosis, and induced cell cycle arrest in HCC cell lines in vitro and in vivo. Screening of cell cycle-related proteins revealed that CCNL2, CDK6, CCNE1, and CCND1 exhibited a significantly different expression profile. We found that SCUBE3 may promote the proliferation of HCC cells by regulating CCNE1 expression. The pathway enrichment analysis showed that the TGFβ signalling pathway and the PI3K/AKT signalling pathway were significantly altered. Co-immunoprecipitation results showed that SCUBE3 binds to the TGFβRII receptor. SCUBE3 knockdown inhibited the PI3K/AKT signalling pathway and the phosphorylation of GSK3β to inhibit its kinase activity. Conclusions SCUBE3 promotes HCC development by regulating CCNE1 via TGFβ/PI3K/AKT/GSK3β pathway. In addition, SCUBE3 may be a new molecular target for the clinical diagnosis and treatment of HCC.

Fbxw11 Variants Promotes Proliferation of Leukemia Cells By Activating the NF-κB Signaling Pathway

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 894-894
Author(s):  
Lina Wang ◽  
Jinfeng Liao ◽  
Wenli Feng ◽  
Xiao Yang ◽  
Shayan Chen ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Signaling Pathway ◽  
Cell Apoptosis ◽  
Leukemia Cells ◽  
Control Group ◽  
Over Expression

Abstract Fbxw11, as a member of F-box proteins family, is a constituent of the SCF (Skp1-Cul1-F box) ubiquitin ligase complex. This ligase ubiquitinates specifically phosphorylated substrates and controls the degradation and half-life of key cellular regulators. So, Fbxw11 play a pivotal role in many aspects of hematopoiesis and tumorigenesis through regulating various signal transduction pathways. We found two transcript variants (Fbxw11c and Fbxw11d) in mouse bone marrow. However the role of Fbxw11 variants in the development of leukemia and the underlying mechanisms remain largely unknown. In this study, we cloned three transcript variants (Fbxw11a, Fbxw11c and Fbxw11d) to study the biological function of Fbxw11 in leukemia. In order to investigate the role of Fbxw11 variants in leukemia, we established L1210 cell lines with over-expression of Fbxw11a, Fbxw11c and Fbxw11d respectively using the lentivirus system. The effect of Fbxw11 variants on proliferation of leukemia cells in vitro was first detected. Growth curve of leukemia cells with Fbxw11a, Fbxw11c or Fbxw11d over-expression was established by cell counting. The results suggested that over-expression of Fbxw11 variants stimulated the growth of leukemia cells. Then MTT experiment was carried out to study the effect of Fbxw11 variants on leukemia cell proliferation and the results showed that Fbxw11 variants increased the proliferation of L1210 cells in vitro. To further confirm the effects of Fbxw11 variants on proliferation of leukemia cells in vivo, tumor xenografts model with over-expression of Fbxw11a, Fbxw11c and Fbxw11d in DBA/2 mice was established. Leukemia cells L1210 with over-expression of Fbxw11a, Fbxw11c and Fbxw11d respectively were transplanted into DBA/2 mice by hypodermic injection. The tumor growth curves showed that tumor growth was increased in Fbxw11 variants over-expression group compared to the control group. Mice were sacrificed on day 28 after transplantation, greater volume of the xenograft tumors were obtained from Fbxw11 variants over-expression group than control group. Therefore, Over-expression of Fbxw11 variants could increase growth of tumor in vivo. To further investigate the molecular mechanism under the effect of Fbxw11 variants on proliferation of leukemia cells, we tested the apoptosis and cell cycle of leukemia cells with Fbxw11 variants over-expression. Over-expression of Fbxw11 variants did not affect the cell apoptosis but accelerated the process of cell cycle. These results revealed that the increased cell proliferation was not due to decrease in cell apoptosis but due to increase in cell cycle. In addition, we tested the effect of Fbxw11 variants on the signal transduction by dual-luciferase reporter gene system. The results showed that over-expression of Fbxw11 variants caused the activation of NF-κB signaling pathway. In conclusion, our findings suggest that Fbxw11 variants have promoting effect on cell proliferation of leukemia cells. The effect of Fbxw11 variants on cell proliferation are due to accelerated the process of cell cycle but not decreasing in cell apoptosis. Further study demonstrated that Fbxw11 variants promote cell proliferation through activating the NF-κB signaling pathway. The important role of Fbxw11 in regulating the development of leukemia suggests that a potent rationale for developing Fbxw11 as a potential therapeutic target against leukemia. Disclosures No relevant conflicts of interest to declare.

scholarly journals BRD4 PROTAC degrader ARV-825 inhibits T-cell acute lymphoblastic leukemia by targeting 'Undruggable' Myc-pathway genes

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Shuiyan Wu ◽  
You Jiang ◽  
Yi Hong ◽  
Xinran Chu ◽  
Zimu Zhang ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Acute Lymphoblastic Leukemia ◽  
Caspase 3 ◽  
Lymphoblastic Leukemia ◽  
Rna Seq ◽  
Cell Acute Lymphoblastic Leukemia ◽  
Bet Protein

Abstract Background T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive disease with a high risk of induction failure and poor outcomes, with relapse due to drug resistance. Recent studies show that bromodomains and extra-terminal (BET) protein inhibitors are promising anti-cancer agents. ARV-825, comprising a BET inhibitor conjugated with cereblon ligand, was recently developed to attenuate the growth of multiple tumors in vitro and in vivo. However, the functional and molecular mechanisms of ARV-825 in T-ALL remain unclear. This study aimed to investigate the therapeutic efficacy and potential mechanism of ARV-825 in T-ALL. Methods Expression of the BRD4 were determined in pediatric T-ALL samples and differential gene expression after ARV-825 treatment was explored by RNA-seq and quantitative reverse transcription-polymerase chain reaction. T-ALL cell viability was measured by CCK8 assay after ARV-825 administration. Cell cycle was analyzed by propidium iodide (PI) staining and apoptosis was assessed by Annexin V/PI staining. BRD4, BRD3 and BRD2 proteins were detected by western blot in cells treated with ARV-825. The effect of ARV-825 on T-ALL cells was analyzed in vivo. The functional and molecular pathways involved in ARV-825 treatment of T-ALL were verified by western blot and chromatin immunoprecipitation (ChIP). Results BRD4 expression was higher in pediatric T-ALL samples compared with T-cells from healthy donors. High BRD4 expression indicated a poor outcome. ARV-825 suppressed cell proliferation in vitro by arresting the cell cycle and inducing apoptosis, with elevated poly-ADP ribose polymerase and cleaved caspase 3. BRD4, BRD3, and BRD2 were degraded in line with reduced cereblon expression in T-ALL cells. ARV-825 had a lower IC50 in T-ALL cells compared with JQ1, dBET1 and OTX015. ARV-825 perturbed the H3K27Ac-Myc pathway and reduced c-Myc protein levels in T-ALL cells according to RNA-seq and ChIP. In the T-ALL xenograft model, ARV-825 significantly reduced tumor growth and led to the dysregulation of Ki67 and cleaved caspase 3. Moreover, ARV-825 inhibited cell proliferation by depleting BET and c-Myc proteins in vitro and in vivo. Conclusions BRD4 indicates a poor prognosis in T-ALL. The BRD4 degrader ARV-825 can effectively suppress the proliferation and promote apoptosis of T-ALL cells via BET protein depletion and c-Myc inhibition, thus providing a new strategy for the treatment of T-ALL.

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