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.

Knockdown of RNF2 enhances the radiosensitivity of squamous cell carcinoma in lung

2019 ◽  
Vol 97 (5) ◽  
pp. 589-599 ◽  
Author(s):  
Jie Yang ◽  
Fan Yu ◽  
Jinlei Guan ◽  
Tao Wang ◽  
Changjiang Liu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Squamous Cell Carcinoma ◽  
Cell Carcinoma ◽  
Squamous Cell ◽  
Cell Apoptosis ◽  
X Ray ◽  
Stable Transfectants

A previous study has reported that knockdown of RING finger protein 2 (RNF2) increases the radiosensitivity of esophageal cancer cells both in vitro and in vivo. However, the effect of RNF2 knockdown on radiosensitivity in squamous cell carcinoma (SqCC) remains unknown. For this, NCI-H226 and SK-MES-1 cells were exposed to X-ray irradiation and then RNF2 levels were determined. RNF2 was knocked-down and stable transfectants were selected. Radiosensitivity, cell proliferation, apoptosis, cell cycle, and γ-H2AX foci formation were evaluated. Interaction among ataxia telangiectasia mutated protein (ATM), mediator of DNA damage checkpoint 1 (MDC1), and H2AX were examined. Xenograft models were used to explore the effect of RNF2 knockdown on radiosensitivity in vivo. The results showed that RNF2 expression was significantly increased by X-ray irradiation. RNF2 knockdown combined with X-ray irradiation markedly inhibited cell proliferation, caused cell cycle arrest at the G1 phase, and induced cell apoptosis. In addition, RNF2 knockdown enhanced the radiosensitivity of SqCC cells, inhibited irradiation-induced γ-H2AX foci formation, and impaired the interactions among ATM, MDC1, and H2AX. Furthermore, combination of RNF2 knockdown and X-ray irradiation suppressed tumor growth and promoted tumor cell apoptosis in vivo. RNF2 may be a new therapeutic target to enhance the radiosensitivity of SqCC cells in lung.

scholarly journals Polyphyllin I Promoted Melanoma Cells Autophagy and Apoptosis via PI3K/Akt/mTOR Signaling Pathway

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Jianwen Long ◽  
Xianming Pi
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Signaling Pathway ◽  
Melanoma Cell ◽  
Cell Apoptosis ◽  
Signal Pathway ◽  
Mtor Signaling ◽  
Mtor Signaling Pathway ◽  
A375 Cells

To investigate whether Polyphyllin I (PPI) might induce the autophagy and apoptosis of melanoma cells by regulating PI3K/Akt/mTOR signal pathway. Melanoma A375 cells were incubated with different concentrations of Polyphyllin I (0, 1.5, 3.0, and 6.0 mg/L) and PI3K/Akt/mTOR signaling pathway activator IGF-1(20 mg/L). CCK-8 assay was utilized to detect cell proliferation; Cell apoptosis and cell cycle were measured by flow cytometry; Western blot was used to examine the expressions of proteins. Immunofluorescence analysis was performed to evaluate autophagy of A375 cells; In addition, xenograft-bearing nude mice were applied to study the role of Polyphyllin I on melanoma development, melanoma cell proliferation, as well as melanoma cell apoptosis in vivo. The outcomes represented that Polyphyllin I promoted A375 cell apoptosis via upregulating Bax level and cleaved caspase-3 level and downregulating Bcl-2 level, inhibited the growth of A375 cells at the G0/G1 phase, and enhanced cell autophagy via regulating the levels of Beclin 1, LC3II, and p62. However, IGF-1 (an activator of PI3K/Akt/mTOR signal pathway) attenuated these changes that Polyphyllin I induced. Furthermore, the xenograft model experiment confirmed that Polyphyllin I treatment suppressed xenograft tumor growth, increased apoptotic index evaluated by the TUNEL method, and reduced the level of Ki67 in tumor tissues in vivo. In conclusion, Polyphyllin I treatment enhanced melanoma cell autophagy and apoptosis, as well as blocked melanoma cell cycle via suppressing PI3K/Akt/mTOR signal pathway. Meanwhile, Polyphyllin I treatment suppressed the development of melanoma in vivo. Therefore, Polyphyllin I possibly is a promising molecular targeted agent used in melanoma therapy.

scholarly journals KCNQ1OT1 regulates the retinoblastoma cell proliferation, migration and SIRT1/JNK signaling pathway by targeting miR-124/SP1 axis

2020 ◽  
Author(s):  
Haitao Zhang ◽  
Xin Yang ◽  
Yingying Xu ◽  
Haijun Li
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Signaling Pathway ◽  
Cell Apoptosis ◽  
Underlying Mechanism ◽  
Luciferase Reporter ◽  
Jnk Signaling ◽  
Retinoblastoma Cell ◽  
Jnk Signaling Pathway

Objective: Long non-coding RNA (lncRNA) KCNQ1OT1 was reported to be tightly associated with tumorigenesis and progression of multiple cancers. However, the expression and biological functions of KCNQ1OT1 in retinoblastoma (RB) are still unknown. We aim to elucidate the potential function and underlying mechanism of KCNQ1OT1 in regulating the progression of RB. Methods: The levels of KCNQ1OT1 were assayed by RT-qPCR analysis. The cell proliferation of RB cells (Y79 and WERI-Rb-1) were evaluated through CCK-8 assay. Meanwhile, Y79 and WERI-Rb-1 cell apoptosis and cell cycle were assessed by Flow Cytometry analysis. Dual luciferase reporter assay were performed to illustrate the interaction between KCNQ1OT1, miR-124, and SP1. Results: We found that KCNQ1OT1 was upregulated and miR-124 was downregulated in RB tissues and cells. Moreover, knockdown of KCNQ1OT1 reduced the proliferation, migration, and cell cycle, as well as promoted cell apoptosis of Y79 and WERI-Rb-1 cells. Western blot analysis consistently proved cell cycle and apoptosis related proteins expression levels. More importantly, KCNQ1OT1 was a sponge of microRNA (miR)-124. MiR-124 inhibition strongly reversed the effect on cell proliferation, cycle arrest, and apoptosis by KCNQ1OT1 knockdown mediated. In addition, KCNQ1OT1 regulated expression of SP1, a directly target of miR-124 in RB. On the other hand, miR-124 inhibitor abrogated the active effect of KCNQ1OT1 silencing on silent information regulator 1 (SIRT1)/c-Jun N-terminal kinase (JNK) signaling pathway.  The function of KCNQ1OT1 was verified in vivo. Conclusions: These findings implied that KCNQ1OT1 silencing inhibited RB progression and activated SIRT1/JNK signaling pathway partially by modulating the miR-124/SP1 axis.

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.

GDF11 impairs liver regeneration in mice after partial hepatectomy

2019 ◽  
Vol 133 (20) ◽  
pp. 2069-2084
Author(s):  
Wenjie Wang ◽  
Xiao Yang ◽  
Jiankun Yang ◽  
Shenpei Liu ◽  
Yongman Lv ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Liver Regeneration ◽  
Signaling Pathway ◽  
Partial Hepatectomy ◽  
Neutralizing Antibodies ◽  
Cell Cycle Progression ◽  
Transforming Growth Factor

Abstract Growth differentiation factor 11 (GDF11) is a member of the transforming growth factor (TGF)-β superfamily. The rejuvenative effect of GDF11 has been called into question recently, and its role in liver regeneration is unclear. Here, we investigated the pathophysiologic role of GDF11, as well as its plausible signaling mechanisms in a mouse model of partial hepatectomy (PH). We demonstrated that both serum and hepatic GDF11 protein expression increased following PH. Treatment with adeno-associated viruses-GDF11 and recombinant GDF11 protein severely impaired liver regeneration, whereas inhibition of GDF11 activity with neutralizing antibodies significantly improved liver regeneration after PH. In vitro, GDF11 treatment significantly delayed cell proliferation and induced cell-cycle arrest in α mouse liver 12 (AML12) cells. Moreover, GDF11 activated TGF-β-SMAD2/3 signaling pathway. Inhibition of GDF11-induced SMAD2/3 activity significantly blocked GDF11-mediated reduction in cell proliferation both in vivo and in vitro. In the clinical setting, GDF11 levels were significantly elevated in patients after hepatectomy. Collectively, these results indicate that rather than a ‘rejuvenating’ agent, GDF11 impairs liver regeneration after PH. Suppression of cell-cycle progression via TGF-β-SMAD2/3 signaling pathway may be a key mechanism by which GDF11 inhibits liver regeneration.

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.

scholarly journals Overexpression of long non-coding RNA LINC00982 suppresses cell proliferation and tumor growth of papillary thyroid carcinoma through PI3K-ATK signaling pathway

2019 ◽  
Vol 39 (7) ◽  
Author(s):  
Debin Xu ◽  
Jichun Yu ◽  
Shimin Zhuang ◽  
Shuyong Zhang ◽  
Zhengdong Hong ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Signaling Pathway ◽  
Cell Apoptosis ◽  
Akt Signaling ◽  
Akt Signaling Pathway ◽  
Expression Levels ◽  
And Migration ◽  
Proliferation And Migration

Abstract Long non-coding RNAs (lncRNAs) have been widely reported that involved in human cancers, including papillary thyroid carcinoma (PTC). The present study aims to investigate the biological role of LINC00982 in PTC. The mRNA expression of LINC00982 in human PTC tissues was detected using qPCR. Moreover, Kaplan–Meier method was performed to analyze the internal relevance between LINC00982 expression and overall survival (OS) rate of patients with PTC. In addition, gain- and loss-of-functions assays were performed to detect the effects of LINC00982 on the cell proliferation and migration in PTC cells. Furthermore, western blot assay was used to measure the alteration expression levels of apoptosis relative proteins and the relative protein involved phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway. Finally, a xenograft model was used to analyze the antitumor role of LINC00982 in vivo. Here, we found that LINC00982 was decreased in human PTC tissues. Patients with decreased LINC00982 expression levels had a reduced OS (P=0.0019) compared with those with high LINC00982 expression levels. Overexpression of LINC00982 suppressed the proliferation and migration of BHT101 and B-CPAP cells and promoted cell apoptosis. Knockdown of LINC00982 promoted the proliferation and migration of BHT101 and B-CPAP cells and induced cell apoptosis. Moreover, in vivo assay showed that overexpression of LINC00982 could suppress the growth of PTC. Finally, LINC00982 could regulate the activity of PI3K/AKT signaling pathway in vitro and in vivo. Taken together, our findings demonstrated that overexpression of LINC00982 could suppress cell proliferation and induce cell apoptosis by regulating PI3K/AKT signaling pathway in PTC.

scholarly journals Down-Regulating HAUS6 Suppresses Cell Proliferation by Activating the p53/p21 Pathway in Colorectal Cancer

2022 ◽  
Vol 9 ◽  
Author(s):  
Aling Shen ◽  
Liya Liu ◽  
Yue Huang ◽  
Zhiqing Shen ◽  
Meizhu Wu ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Cell Cycle ◽  
Cell Proliferation ◽  
Cell Viability ◽  
Cell Cycle Progression ◽  
Cycle Progression ◽  
Over Expression ◽  
Mrna And Protein Expression

Background: HAUS6 participates in microtubule-dependent microtubule amplification, but its role in malignancies including colorectal cancer (CRC) has not been explored. We therefore assessed the potential oncogenic activities of HAUS6 in CRC.Results: HAUS6 mRNA and protein expression is higher in CRC tissues, and high HAUS6 expression is correlated with shorter overall survival in CRC patients. HAUS6 knockdown in CRC cell lines suppressed cell growth in vitro and in vivo by inhibiting cell viability, survival and arresting cell cycle progression at G0/G1, while HAUS6 over-expression increased cell viability. We showed that these effects are dependent on activation of the p53/p21 signalling pathway by reducing p53 and p21 degradation. Moreover, combination of HAUS6 knockdown and 5-FU treatment further enhanced the suppression of cell proliferation of CRC cells by increasing activation of the p53/p21 pathway.Conclusion: Our study highlights a potential oncogenic role for HAUS6 in CRC. Targeting HAUS6 may be a promising novel prognostic marker and chemotherapeutic target for treating CRC patients.

Oncogenic Role for the Lck/ZAP70/PLCG2 Signaling Pathway in Pre-B-ALL Pathogenesis

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 810-810 ◽  
Author(s):  
Jesus Duque-Afonso ◽  
Michael C. Wei ◽  
Chiou-Hong Lin ◽  
Jue Feng ◽  
Corina Buechele ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cell Proliferation ◽  
Bone Marrow Transplantation ◽  
Signaling Pathways ◽  
Signaling Pathway ◽  
Marrow Transplantation ◽  
Target Genes ◽  
Leukemia Cells

Abstract Although the treatment and prognosis of patients with pediatric acute lymphoblastic leukemia (ALL) have improved during the last decades, there is still a clinical need for more effective/selective and less toxic therapies. To address this, we have interrogated various signaling pathways in human ALL cells and mouse strains that express E2A-PBX1, which is present in 5-7% of pediatric ALL. Phospho-flow analysis revealed basal hyper-phosphorylation levels of PLCγ2 in mouse E2A-PBX1 leukemias, consistent with hyper-activation of upstream signaling pathways. Efficient shRNA-mediated depletion of PLCγ2 reduced colony formation of mouse E2A-PBX1+ leukemias in vitro and increased disease-free survival after secondary bone marrow transplantation in vivo. Furthermore, PLCγ2-depleted human ALL cell lines including E2A-PBX1+ cells, showed reduced proliferation. These data suggest a pathogenic role of hyperactivated PLCγ2 in pre-B-ALL. Bioinformatics analysis of E2A-PBX1 target genes in human ALLs revealed an enrichment of B- and T-cell activation pathways, which include the SRC-family kinase LCK and the cytoplasmic kinase ZAP70, upstream of PLCγ2. Comparative analyses of global transcriptional profiles in human primary and mouse leukemias and preleukemias induced by the E2A-PBX1 oncogene identified the signaling kinase ZAP70 as one of the earliest and most consistently up-regulated genes in E2A-PBX1 leukemias. Using a candidate gene approach, we identified LCK with increased expression levels in E2A-PBX1 leukemia cells compared to normal B-cell progenitors. Mouse and human E2A-PBX1 leukemia cells were dependent on the E2A-PBX1 target genes ZAP70 and LCK for proliferation and survival as confirmed by shRNA knock-down experiments. Hence, efficient depletion of these genes resulted in a decrease of phosphorylated PLCγ2, suggesting therapeutic targets in E2A-PBX1 leukemias. Combined suppression of ZAP70 and LCK using double-shRNA experiments showed an additive effect on inhibition of cell proliferation and decrease of phosphorylated PLCγ2. These results provide a rationale for combination therapy to block this hyper-activated signaling pathway at different levels. Several small molecule inhibitors were evaluated for their effects on PLCγ2 upstream pathways in E2A-PBX1 leukemia cells. SRC-family kinase inhibitors including dasatinib were most effective in reducing phosphorylation of PLCγ2 and inhibiting cell proliferation. Furthermore, dasatinib showed promising preclinical efficacy in vitro in colony forming assays and in vivo after secondary bone marrow transplantation of leukemias. In summary, our studies demonstrate that the proliferation and survival of E2A-PBX1 leukemias are dependent on PLCγ2 and upstream signaling pathways, which are suitable for pharmacological inhibition. Disclosures No relevant conflicts of interest to declare.

Preclinical study of MEK1/2 inhibitor AZD6244 combined with gemcitabine for treatment of biliary cancer.

2012 ◽  
Vol 30 (4_suppl) ◽  
pp. 240-240
Author(s):  
Junyao Xu ◽  
Jennifer J. Knox ◽  
Ming Sound Tsao ◽  
Eric Xueyu Chen ◽  
Pinjiang Cao ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Signaling Pathway ◽  
Cell Lines ◽  
Preclinical Study ◽  
Erk Signaling ◽  
Therapeutic Effects ◽  
Biliary Cancer

240 Background: MEK1/2 is an integral component of the Ras/Raf/MEK/ERK signaling pathway, implicated in uncontrolled cell proliferation and cell survival, a key hallmark of cancer. AZD6244, a novel inhibitor of MEK1/2, is currently completing Phase II clinical trials in biliary cancer, with modest antitumor activity observed as monotherapy. Gemcitabine is a cytotoxic drug commonly used in biliary cancer therapy but many patients showed early resistance. In this preclinical study, we investigated the sequence-dependent antitumor effects of AZD6244 combined with gemcitabine in biliary cancer models. Methods: Two biliary cancer cell lines (EGI-1 and TFK-1) were used. In vitro the effects of single drug or three combination protocols(concurrently; AZD6244 followed by GEM or Gem followed by AZD6244) on cell proliferation, DNA synthesis, and cell cycle distribution were evaluated by MTS, clonogenic assay, EdU uptake and flow cytometry. Drug interactions were analyzed by Chou-Talaly method. In vivo, 4 tumor models subcutaneously xenografted in SCID mice from the two cell lines and 2 human patients were set up to compare the therapeutic effects of different sequence-scheduled combinations. Results: AZD6244 caused G1-S cell cycle arrest in biliary cancer cells in vitro and in vivo, and this effect is correlated with the MEK/ERK signaling pathway blocking. Synchronized progression of the population through S phase were observed in 15h after removal of AZD6244 in cell culture or 48h after final dose of acute AZD6244 treatment in vivo. Antagonistic or additive effects was observed in vitro when combination were given as concurrently(CI=2.03~2.46) or Gem followed by AZD6244(CI=1.34~1.78). In contrast, a synergistic antiproliferative activity was obtained when AZD6244 was given first followed by a drug-free interval before Gem treatment (CI=0.53~0.69). In vivo, the best therapeutic effects were obtained with the sequence of AZD6244 followed by Gem, compared with concurrent or reverse sequence. Conclusions: This study provides a sound rationale for a Phase II trial of a potentially synergistic sequence of MEK inhibitor AZD6244 followed by gemcitabine in patients with advanced biliary cancer.

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