TrkC promotes survival and growth of leukemia cells through Akt-mTOR-dependent up-regulation of PLK-1 and Twist-1.
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ABSTRACT:
SUBMITTER: Kim MS
PROVIDER: S-EPMC3887946 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Background: The conventional chemotherapeutic regimens which applied for treatment of acute myeloid leukemia (AML) mostly target tumor bulk but not leukemic stem cells (LSCs). Aberrant expression or activation of mediators such as osteopontin (OPN) or PI3K/PTEN/Akt/mTOR pathway plays a key role in making prone to develop leukemia. Preventing or treating cancer by curcumin (CUR) has been suggested recently. CUR induces apoptosis and growth inhibition through various mechanisms in leukemic cells. In present study, we tried to measure the toxic response in vitro to CUR for evaluation ofchangesin cell viability, survival and molecular-mediated resistance in primary AML cells. Materials and Methods: Isolated primary CD34+/CD38- bone marrow derived AML cells were treated with CUR, Daunorubicin (DNR) and/or their combination by MTT assay, Annexin V/PI staining, and colony-formation. The mRNA expression of OPN/AKT/mTOR/PTEN/?-catenin genes was measured by Real-Time PCR. The siRNA against OPN was applied for CUR- treated cells. Results: Growth inhibition effect of DNR increased in combination with CUR on primary CD34+/CD38- AML cells. Suppression of OPN with siRNA increased the cytotoxic effects of CUR. Likewise, OPN gene expression increased in response to CUR treatment in AML cells. AKT, mTOR, ?-catenin or PTEN gene expression increased by CUR, but OPN siRNA decreased the level of mRNA expression of mentioned molecular pathway. Conclusion: The chemo-resistance of AML cells against therapy might be relevant to increasing of OPN mRNA expression and activity of other mediators including AKT, mTOR, PTEN, and ?-catenin. In this context, targeting of OPN might be more impact on CD34+ AML cells.
| S-EPMC5574411 | biostudies-literature
Project description:BACKGROUND: Fragile X syndrome (FXS), the most commonly inherited mental retardation and single gene cause of autistic spectrum disorder, occurs when the Fmr1 gene is mutated. The product of Fmr1, fragile X linked mental retardation protein (FMRP) is widely expressed in HeLa cells, however the roles of FMRP within HeLa cells were not elucidated, yet. Interacting with a diverse range of mRNAs related to cellular survival regulatory signals, understanding the functions of FMRP in cellular context would provide better insights into the role of this interesting protein in FXS. Using HeLa cells treated with etoposide as a model, we tried to determine whether FMRP could play a role in cell survival. METHODS: Apoptotic cell death was induced by etoposide treatment on Hela cells. After we transiently modulated FMRP expression (silencing or enhancing) by using molecular biotechnological methods such as small hairpin RNA virus-induced knock down and overexpression using transfection with FMRP expression vectors, cellular viability was measured using propidium iodide staining, TUNEL staining, and FACS analysis along with the level of activation of PI3K-Akt pathway by Western blot. Expression level of FMRP and apoptotic regulator BcL-xL was analyzed by Western blot, RT-PCR and immunocytochemistry. RESULTS: An increased FMRP expression was measured in etoposide-treated HeLa cells, which was induced by PI3K-Akt activation. Without FMRP expression, cellular defence mechanism via PI3K-Akt-Bcl-xL was weakened and resulted in an augmented cell death by etoposide. In addition, FMRP over-expression lead to the activation of PI3K-Akt signalling pathway as well as increased FMRP and BcL-xL expression, which culminates with the increased cell survival in etoposide-treated HeLa cells. CONCLUSIONS: Taken together, these results suggest that FMRP expression is an essential part of cellular survival mechanisms through the modulation of PI3K, Akt, and Bcl-xL signal pathways.
| S-EPMC3045291 | biostudies-literature
Project description:It was shown that endothelial progenitor cells (EPCs) have bidirectional differentiation potential and thus perform different biological functions. The purpose of this study was to investigate the effects of slight up-regulation of the Kir2.1 channel on EPC transdifferentiation and the potential mechanism on cell function and transformed cell type. First, we found that the slight up-regulation of Kir2.1 expression promoted the expression of the stem cell stemness factors ZFX and NS and inhibited the expression of senescence-associated β-galactosidase. Further studies showed the slightly increased expression of Kir2.1 could also improve the expression of pericyte molecular markers NG2, PDGFRβ and Desmin. Moreover, adenovirus-mediated Kir2.1 overexpression had an enhanced contractile response to norepinephrine of EPCs. These results suggest that the up-regulated expression of the Kir2.1 channel promotes EPC transdifferentiation into a pericyte phenotype. Furthermore, the mechanism of EPC transdifferentiation to mesenchymal cells (pericytes) was found to be closely related to the channel functional activity of Kir2.1 and revealed that this channel could promote EPC EndoMT by activating the Akt/mTOR/Snail signalling pathway. Overall, this study suggested that in the early stage of inflammatory response, regulating the Kir2.1 channel expression affects the biological function of EPCs, thereby determining the maturation and stability of neovascularization.
| S-EPMC8572793 | biostudies-literature
Project description:Tropomyosin-related kinase receptor C (TrkC) is a neurotrophin receptor with tyrosine kinase activity that was expected to be oncogenic. However, it has several characteristics of a tumor suppressor: its expression in tumors has often been associated with good prognosis; and it was recently demonstrated to be a dependence receptor, transducing different positive signals in the presence of ligand but inducing apoptosis in the absence of ligand. Here we show that the TrkC ligand neurotrophin-3 (NT-3) is upregulated in a large fraction of aggressive human neuroblastomas (NBs) and that it blocks TrkC-induced apoptosis of human NB cell lines, consistent with the idea that TrkC is a dependence receptor. Functionally, both siRNA knockdown of NT-3 expression and incubation with a TrkC-specific blocking antibody triggered apoptosis in human NB cell lines. Importantly, disruption of the NT-3 autocrine loop in malignant human neuroblasts triggered in vitro NB cell death and inhibited tumor growth and metastasis in both a chick and a mouse xenograft model. Thus, we believe that our data suggest that NT-3/TrkC disruption is a putative alternative targeted therapeutic strategy for the treatment of NB.
| S-EPMC2827960 | biostudies-literature
Project description:Many long noncoding RNAs have been implicated in tumorigenesis and chemoresistance; however, the underlying mechanisms are not well understood. We investigated the role of PRKAR1B-AS2 long noncoding RNA in ovarian cancer (OC) and chemoresistance and identified potential downstream molecular circuitry underlying its action. Analysis of The Cancer Genome Atlas OC dataset, in vitro experiments, proteomic analysis, and a xenograft OC mouse model were implemented. Our findings indicated that overexpression of PRKAR1B-AS2 is negatively correlated with overall survival in OC patients. Furthermore, PRKAR1B-AS2 knockdown-attenuated proliferation, migration, and invasion of OC cells and ameliorated cisplatin and alpelisib resistance in vitro. In proteomic analysis, silencing PRKAR1B-AS2 markedly inhibited protein expression of PI3K-110α and abrogated the phosphorylation of PDK1, AKT, and mTOR, with no significant effect on PTEN. The RNA immunoprecipitation detected a physical interaction between PRKAR1B-AS2 and PI3K-110α. Moreover, PRKAR1B-AS2 knockdown by systemic administration of 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine nanoparticles loaded with PRKAR1B-AS2-specific small interfering RNA enhanced cisplatin sensitivity in a xenograft OC mouse model. In conclusion, PRKAR1B-AS2 promotes tumor growth and confers chemoresistance by modulating the PI3K/AKT/mTOR pathway. Thus, targeting PRKAR1B-AS2 may represent a novel therapeutic approach for the treatment of OC patients.
| S-EPMC7918312 | biostudies-literature
Project description:BackgroundAtherosclerosis is one of the most common cardiovascular disorders. The dysfunction of vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) are 2 key factors in the formation of atherosclerosis. This study aims to find strategies to prevent VSMCs and ECs dysfunction for the treatment of atherosclerosis.MethodsWe investigated the expression patterns of long noncoding RNAs (lncRNAs) in 2 pairs of serum samples from both atherosclerosis patients and healthy volunteers through microarray analysis. Then we selected the most up-regulated lncRNA ENAST00113 (lnc00113) to further verify its roles in atherosclerosis. VSMCs, and human umbilical vein endothelial cells (HUVECs) transfected with small interfering RNA (siRNAs) (si-00113-1, si-00113-1) and a negative control (si-NC) were cultured. MTT assay, Caspase 3 enzyme-linked immunosorbent assay (ELISA) assay, and wound healing assay were performed to evaluate whether lnc00113 had an effect on proliferation, apoptosis, and migration ability. Further, the correlation between lnc00113 and PI3K/Akt/mTOR signaling pathway was explored.ResultsMicroarray results indicated that 243 lncRNAs were up-regulated and 187 lncRNAs were down-regulated. Therefore, we chose the most up-regulated lncRNA ENST (lnc00113) to further explore its roles in atherosclerosis. Real-time polymerase chain reaction (RT-qPCR) results showed that the expression of lnc00113 was highly increased in atherosclerosis patients. In vitro experiment demonstrated that lnc00113 down-regulation significantly suppressed VSMCs and HUVECs proliferation, survival, and migration. Furthermore, we found that the protein expressions of phosphorylated-PI3K (p-PI3K), phosphorylated-Akt (p-Akt), phosphorylated-mTOR (p-mTOR), and bcl-2 in HUVECs cells transfected with si-00113-1 or si-00113-2 were dramatically decreased compared with si-NC-transfected cells and control cells. However, the total- PI3K (t-PI3K), total-Akt (t-Akt), and total-mTOR (t-mTOR) protein expressions were not changed, indicating that lnc00113 could activate PI3K/Akt/mTOR signaling pathway in atherosclerosis.ConclusionsThis finding identified an important role of lnc00113 in VSMCs and HUVECs that promotes cell proliferation, survival, and migration by activating PI3K/Akt/mTOR signaling pathway, which could probably serve as a promising therapeutic target for atherosclerosis.
| S-EPMC5916647 | biostudies-literature
Project description:Technological advances allowing high throughput analyses across numerous cancer tissues have allowed much progress in understanding complex cellular signaling. In the future, the genetic landscape in cancer may have more clinical relevance than diagnosis based on tumor origin. This progress has emphasized PI3K/AKT/mTOR, among others, as a central signaling center of cancer development due to its governing control in cellular growth, survival, and metabolism. The discovery of high frequencies of mutations in the PI3K/AKT/mTOR pathway in different cancer entities has sparked interest to inhibit elements of this pathway. In acute leukemia pharmacological interruption has yet to achieve desirable efficacy as targetable downstream mutations in PI3K/AKT/mTOR are absent. Nevertheless, mutations in membrane-associated genes upstream of PI3K/AKT/mTOR are frequent in acute leukemia and are associated with aberrant activation of PI3K/AKT/mTOR thus providing a good rationale for further exploration. This review attempts to summarize key findings leading to aberrant activation and to reflect on both promises and challenges of targeting PI3K/AKT/mTOR in acute leukemia. Our emphasis lies on the insights gained through high-throughput data acquisition that open up new avenues for identifying specific subgroups of acute leukemia as ideal candidates for PI3K/AKT/mTOR targeted therapy.
| S-EPMC4452048 | biostudies-literature
Project description:EPHB4, an ephrin type B receptor, is implicated in the growth of several epithelial tumors and is a promising target in cancer therapy; however, little is known about its role in hematologic malignancies. In this article, we show that EPHB4 is highly expressed in ∼30% of acute myeloid leukemia (AML) samples. In an unbiased RNA interference screen of primary leukemia samples, we found that EPHB4 drives survival in a subset of AML cases. Knockdown of EPHB4 inhibits phosphatidylinositol 3-kinase/AKT signaling, and this is accompanied by a reduction in cell viability, which can be rescued by a constitutively active form of AKT. Finally, targeting EPHB4 with a highly specific monoclonal antibody (MAb131) is effective against AML in vitro and in vivo. EPHB4 is therefore a potential target in AML with high EPHB4 expression.
| S-EPMC5728330 | biostudies-literature
Project description:Activating mutations of the FLT3 gene mediate leukemogenesis, at least in part, through activation of PI3K/AKT. The mammalian target of rapamycin (mTOR)-Raptor signaling pathway is known to act downstream of AKT. Here we show that the mTOR effectors, 4EBP1, p70S6K and rpS6, are highly activated in cultured and primary FLT3-mutated acute myeloid leukemia (AML) cells. Introduction of FLT3-ITD expressing constitutively activated FLT3 kinase further activates mTOR and its downstream effectors in BaF3 cells. We also found that mTOR signaling contributes to tumor cell survival, as demonstrated by pharmacologic inhibition of PI3K/AKT/mTOR, or total silencing of the mTOR gene. Furthermore, inhibition of FLT3 kinase results in downregulation of mTOR signaling associated with decreased survival of FLT3-mutated AML cells. These findings suggest that mTOR signaling operates downstream of activated FLT3 kinase thus contributing to tumor cell survival, and may represent a promising therapeutic target for AML patients with mutated-FLT3.
| S-EPMC2993677 | biostudies-other
Project description:BackgroundsCutaneous T cell lymphoma (CTCL) is a non-Hodgkin lymphoma characterized by skin infiltration of malignant T cells. The biological overlap between malignant T cells and their normal counterparts has brought obstacles in identifying tumor-specific features and mechanisms, limiting current knowledge of CTCL pathogenesis. Transcriptional dysregulation leading to abnormal gene expression profiles contributes to the initiation, progression and drug resistance of cancer. Therefore, we aimed to identify tumor-specific transcription factor underlying CTCL pathology.MethodsWe analyzed and validated the differentially expressed genes (DEGs) in malignant T cells based on single-cell sequencing data. Clinical relevance was evaluated based on progression-free survival and time to next treatment. To determine the functional importance, lentivirus-mediated gene knockdown was conducted in two CTCL cell lines Myla and H9. Cell survival was assessed by examining cell viability, colony-forming ability, in-vivo tumor growth in xenograft models, apoptosis rate and cell-cycle distribution. RNA sequencing was employed to investigate the underlying mechanisms.ResultsActivating transcription factor 5 (ATF5) was overexpressed in malignant T cells and positively correlated with poor treatment responses in CTCL patients. Mechanistically, ATF5 promoted the survival of malignant T cells partially through the PI3K/AKT/mTOR pathway, and imparted resistance to endoplasmic reticulum (ER) stress-induced apoptosis.ConclusionsThese findings revealed the tumor-specific overexpression of the transcription factor ATF5 with its underlying mechanisms in promoting tumor survival in CTCL, providing new insight into the understanding of CTCL's pathology.
| S-EPMC10786347 | biostudies-literature