scholarly journals The lipid phosphatase activity of PTEN is critical for stabilizing intercellular junctions and reverting invasiveness

2001 ◽  
Vol 155 (7) ◽  
pp. 1129-1136 ◽  
Author(s):  
Larissa Kotelevets ◽  
Jolanda van Hengel ◽  
Erik Bruyneel ◽  
Marc Mareel ◽  
Frans van Roy ◽  
...  

To analyze the implication of PTEN in the control of tumor cell invasiveness, the canine kidney epithelial cell lines MDCKras-f and MDCKts-src, expressing activated Ras and a temperature-sensitive v-Src tyrosine kinase, respectively, were transfected with PTEN expression vectors. Likewise, the human PTEN-defective glioblastoma cell lines U87MG and U373MG, the melanoma cell line FM-45, and the prostate carcinoma cell line PC-3 were transfected. We demonstrate that ectopic expression of wild-type PTEN in MDCKts-src cells, but not expression of PTEN mutants deficient in either the lipid or both the lipid and protein phosphatase activities, reverted the morphological transformation, induced cell–cell aggregation, and suppressed the invasive phenotype in an E-cadherin–dependent manner. In contrast, overexpression of wild-type PTEN did not counteract Ras-induced invasiveness of MDCKras-f cells expressing low levels of E-cadherin. PTEN effects were not associated with marked changes in accumulation or phosphorylation levels of E-cadherin and associated catenins. Wild-type, but not mutant, PTEN also reverted the invasive phenotype of U87MG, U373MG, PC-3, and FM-45 cells. Interestingly, PTEN effects were mimicked by N-cadherin–neutralizing antibody in the glioblastoma cell lines. Our data confirm the differential activities of E- and N-cadherin on invasiveness and suggest that the lipid phosphatase activity of PTEN exerts a critical role in stabilizing junctional complexes and restraining invasiveness.

Medicina ◽  
2021 ◽  
Vol 57 (9) ◽  
pp. 879 ◽  
Author(s):  
Hye-Sung Lee ◽  
Bong-Soo Park ◽  
Hae-Mi Kang ◽  
Jung-Han Kim ◽  
Sang-Hun Shin ◽  
...  

Background and Objectives: Malignant glioblastoma (GBM) is caused by abnormal proliferation of glial cells, which are found in the brain. The therapeutic effects of surgical treatment, radiation therapy, and chemo-therapy against GBM are relatively poor compared with their effects against other tumors. Luteolin is abundant in peanut shells and is also found in herbs and other plants, such as thyme, green pepper, and celery. Luteolin is known to be effective against obesity and metabolic syndrome. The anti-inflammatory, and anti-cancer activities of luteolin have been investigated. Most studies have focused on the antioxidant and anti-inflammatory effects of luteolin, which is a natural flavonoid. However, the association between the induction of apoptosis by luteolin in GBM and autophagy has not yet been investigated. This study thus aimed to confirm the occurrence of luteolin-induced apoptosis and autophagy in GBM cells and to assess their relationship. Materials and Methods: A172 and U-373MG glioblastoma cell lines were used for this experiment. We confirmed the apoptosis effect of Luteolin on GBM cells using methods such as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, immunofluorescence, Flow cytometry (FACS) western blot, and real-time quantitative PCR (qPCR). Results: In the luteolin-treated A172 and U-373MG cells, cell viability decreased in a concentration- and time-dependent manner. In addition, in A172 and U-373MG cells treated with luteolin at concentrations greater than 100 μM, nuclear fragmentation, which is a typical morphological change characterizing apoptosis, as well as fragmentation of caspase-3 and Poly (ADP-ribose) polymerase (PARP), which are apoptosis-related factors, were observed. Autophagy was induced after treatment with at least 50 μM luteolin. Inhibition of autophagy using 3MA allowed for a low concentration of luteolin to more effectively induce apoptosis in A172 and U-373MG cells. Conclusions: Results showed that luteolin induces apoptosis and autophagy and that the luteolin-induced autophagy promotes cell survival. Therefore, an appropriate combination therapy involving luteolin and an autophagy inhibitor is expected to improve the prognosis of GBM treatment.


2019 ◽  
Vol 37 (15_suppl) ◽  
pp. e13560-e13560
Author(s):  
Dorothee Gramatzki ◽  
Emese Szabo ◽  
Martin Gramatzki ◽  
Matthias Peipp ◽  
Michael Weller

e13560 Background: Glioblastoma is the most common primary malignant brain tumor with a poor prognosis. CD317 (HM1.24) is a transmembrane protein and may exist in differently spliced variants. It is highly expressed on plasma cells in multiple myeloma, as well as in certain solid tumor types. While several antibody drug conjugates are already in clinical practice, small immunotoxins with a different intracellular mode of action are only established in hairy cell leukemia. The immunotoxin HM1.24-ETA’ protein is a CD317 single chain Fv (scFv) antibody fused to a truncated version of Pseudomonas aeruginosa exotoxin A (ETA’). Methods: In vivo CD317 mRNA expression in human glioma of different grades and survival probabilities of glioblastoma patients based on CD317 mRNA expression were analyzed using the database of the Cancer Genome Atlas network (TCGA). CD317 protein expression was analyzed by immunohistochemistry in a human tissue microarray (TMA). In vitro CD317 mRNA expression was assessed by RT-PCR and CD317 protein levels by flow cytometry in several human glioblastoma cell lines. A cytotoxicity assay after treatment with HM1.24-ETA’ immunotoxin was performed in human glioblastoma cell lines. Results: Data on mRNA expression from the TCGA database demonstrated, that CD317 was upregulated in human glioblastomas compared to lower grade gliomas. In the group of glioblastoma patients increased CD317 mRNA expression was associated with decreased probability of survival ( p< 0.001). CD317 protein levels correlated directly with the tumor grade of astrocytic gliomas in the TMA. CD317 was expressed heterogeneously on mRNA and protein levels in the tested cell-lines in vitro. HM1.24-ETA’ induced cytotoxicity in CD317-positive glioblastoma cells in a concentration-dependent manner. Animal experiments currently performed suggest activity in glioblastoma xenografted mice. Conclusions: These data highlight CD317 as an interesting target antigen and HM1.24-ETA’ immunotoxin as a strategy for immunotherapy of glioblastoma patients.


Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2596-2596
Author(s):  
Ismael Samudio ◽  
Martin Dietrich ◽  
Paul Corn ◽  
Dajun Yang ◽  
Gautam Borthakur

Abstract Although TP53 mutations are rare in acute myeloid leukemia (AML), inactivation of wild-type p53 protein frequently occurs through overexpression of its negative regulator MDM2 (murine double minute 2). We investigated the effects of MI-63, a small molecule that activates p53 by inhibition of MDM2-p53 interaction [ Ki value of 3 nM (J Med Chem.2006;49(12):3432–5)] in AML cell lines. Treatment with MI-63 triggered apoptosis (evidenced by loss of membrane potential and externalization of phosphatidylserine) in AML cell lines with wild-type p53 (OCI-AML-3 and MOLM13) in a time and concentration-dependent manner (IC50 at 72 hrs.= 2.5 μM for OCI-AML-3 and 1 μM for MOLM-13), while a p53-null AML cell line (HL-60) was resistant (IC50 not reached at 10 μM). Moreover, knockdown of p53 in OCI-AML3 cells rendered this cell line resistant to MI-63 induced apoptosis while control vector infected OCI-AML-3 cells remained as sensitive to MI-63 similar to the parental cells. Mechanistic studies showed that MI-63 blocks G1/S phase transition in AML cells with wild-type p53 resulting in accumulation of cells in G1 phase (percentage cells inG1 phase at 24 hrs. = 88.66% vs 43.49% in cultures with DMSO control) while MI-61, a skeletally related but inactive control compound failed to do so (41.63%). Treatment with MI-63 increased cellular levels of p53 and p53 dependent proteins in OCI-AML-3 cells that include p21 and BH3-only pro-apoptotic protein Puma and pro-apoptotic multi-domain Bcl-2 family member Bax. Additionally, MI-63 induced a profound decrease in the levels of MDM4, an MDM2 homolog that has been reported to mediate resistance to the effects of nutlin-3a, suggesting that MI-63 may offer a therapeutic advantage in cells expressing high levels of MDM4. Finally, supporting the concept that increased levels of p53 modulate the apoptotic rheostat both directly, by behaving as a BH3-only protein, and indirectly by increasing the levels of sensitizer BH3-only proteins, MI-63 potently synergized with AT-101, an orally available pan inhibitor of Bcl-2, Bcl-xL and Mcl-1 (currently being evaluated as an antitumor agent in Phase I/II trials by Ascenta Therapeutics), to induce mitochondrial dysfunction and apoptosis in OCI-AML-3 cells (average combination index = 0.055±0.019). Taken together our results support preclinical evaluation of novel small molecule MI-63 alone and in combination with Bcl-2 inhibitors for the therapy of AML. The studies in primary AML samples are ongoing. Fig.1: MI-63 Induced Apoptosis Requires Intact p53 Fig.1:. MI-63 Induced Apoptosis Requires Intact p53 Fig.2: Efect of MI-63 on p53 and Related Proteins (comparison with N3a, a known MDM2 inhibitor included) Fig.2:. Efect of MI-63 on p53 and Related Proteins (comparison with N3a, a known MDM2 inhibitor included)


1989 ◽  
Vol 71 (3) ◽  
pp. 388-397 ◽  
Author(s):  
Marco Colombatti ◽  
Bruno Dipasquale ◽  
Lorena Del-l'Arciprete ◽  
Massimo Gerosa ◽  
Giuseppe Tridente

✓ Seven human glioblastoma cell lines established in vitro from primary tumor explants were studied. A marked heterogeneity of glial fibrillary acidic protein was observed whereas vimentin was uniformly expressed by all cell lines. Indirect immunofluorescence and flow cytofluorometry revealed a heterogeneous distribution of surface GE 2 and CG 12 tumor-associated antigens (TAA's): three cell lines were positive (> 69% TAA-positive cells) and three cell lines were negative (< 9% TAA-positive cells). One cell line (Hu 228) was moderately positive at early culture passages and subsequently acquired a TAA-negative phenotype. The difference in the relative amounts of surface TAA's of the three positive cell lines was less than twofold. In spite of the heterogeneous distribution of surface TAA's, all cell lines exhibited considerable amounts of intracellular TAA. Treatment with phorbol esters and density-dependent growth arrest decreased the percentage of the TAA-positive cells and the amount of cell-surface TAA's in one cell line (Hu 195). Interferon-γ treatment in vitro increased the percentage of CG 12-positive cells by 12% and the amount of cell-surface CG 12 antigens by 38% as compared to untreated cells. The percentage of TAA-positive cells among phorbol ester-treated cells of the Hu 195 cell line was lowest 48 hours after treatment, but returned to normal values within the next 48 hours. Reduction of 3H-thymidine incorporation preceded the decrease in number of TAA-positive cells by about 18 hours. Two-color fluorescence analysis performed in positive cell lines for simultaneous determination of surface TAA's and deoxyribonucleic acid content or reactivity with the proliferation-associated Ki67 intracellular marker indicated that GE 2 and CG 12 antigens are expressed preferentially by actively proliferating glioma cells. The results of this study indicate the existence of two different phenotypes in cultured human glioblastoma cells: surface TAA-positive/cytosol TAA-positive and surface TAA-negative/cytosol TAA-positive cell populations. In addition, modulation of TAA expression was dependent on the cell-cycle differentiation stage, culture conditions, and proliferative state of the cells.


2021 ◽  
Vol 23 (Supplement_2) ◽  
pp. ii34-ii34
Author(s):  
M M C Bruce ◽  
M T C Poon ◽  
P M Brennan

Abstract BACKGROUND The alkylating agent temozolomide is part of standard care for patients with glioblastoma. Potential novel therapeutic agents are often first evaluated against temozolomide in glioblastoma cell line models. Despite the importance of this step in compound development, there is no standard concentration or exposure duration of temozolomide in laboratory research, and consistency in the effect of temozolomide on glioblastoma cell lines has not been assessed. This systematic review aimed to summarise the concentration and exposure duration of temozolomide and its effect on cell viability in studies using glioblastoma cell lines. MATERIAL AND METHODS We searched Medline and Embase Jan 1994 - Feb 2021 for studies that used at least one glioblastoma cell line and reported a measure of cell viability associated with temozolomide exposure. Studies were excluded if they used modified cell lines or did not report a cell viability measure associated with temozolomide as monotherapy. One reviewer screened all records and two reviewers assessed potentially eligible studies for inclusion. The main data items included the cell lines used, the concentration and exposure duration to temozolomide, and cell viability measures. We summarised findings using descriptive statistics. RESULTS Of 1,533 potentially eligible studies we included 213 studies reporting 209 different cell lines. The most common cell lines were U87, U251 and T98G, used in 61%, 41%, and 27% of studies, respectively. Twenty-five (12%) studies used patient-derived cell lines. The concentration of temozolomide used ranged from 0 to 8000μM. The temozolomide exposure duration ranged from &lt;24 hours to &gt;96 hours, with 29% studies using 72 hours. The most common cell viability measure was half maximal inhibitory concentration (IC50), which was reported in 183 (86%) studies. The median IC50 in 32 studies using the U87 cell line was 180μM (interquartile range [IQR]: 52–254μM) at 48-hour temozolomide exposure and 202μM (IQR 52–518μM) at 72-hour exposure. The median IC50 in 31 studies using U251 cell line was 84μM (IQR: 34–324μM) at 48-hour exposure and 102μM (IQR: 35–358μM) at 72-hour exposure. CONCLUSION Experimental setup of temozolomide and its effect on cell viability vary widely between studies using similar glioblastoma cell lines. This inconsistency of response to temozolomide questions reproducibility and the translational value of study findings.


2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi77-vi78
Author(s):  
Dylan Harwood ◽  
Signe Michaelsen ◽  
Filip Mundt ◽  
Bjarne Kristensen

Abstract BACKGROUND The standard therapy for glioblastoma patients is tumor resection followed by radiotherapy and temozolomide chemotherapy. Although glioblastoma has been extensively molecularly profiled along with other cancers, this knowledge has not yet been translated into improved survival outcomes. We used a bioinformatics approach to identify potential novel therapeutic strategies for glioblastoma. OBJECTIVES: Comprehensive online datasets which have assessed up to 1376 cancer cell lines in multiple ways were interrogated to identify potential drug candidates for glioblastoma. METHODS Datasets included were from the cancer cell line encyclopedia (mRNA expression), the Achilles project (cell viability following Crispr-Cas9 knockout) and PRISM (drug treatment). A t-test comparing cell viability of glioblastoma cell lines versus other cancers was used to identify potential drug candidates, followed by the use of multiple statistical tools to investigate potential mechanism of action and status of biomarkers. RESULTS Fluvastatin and pitavastatin produced the most significant effects in glioblastoma cell lines. The anti-cancer properties of statins have previously been attributed to the inhibition of HMG-Coa reductase. Here, we found their effects correlated with erastin, an enhancer of ferroptosis and with gene knockout of UBIAD1, which participates in non-mitochondrial ubiquinone synthesis. These effects were both found in glioblastoma cells and other cancers with a mesenchymal-like phenotype. CONCLUSION Statins appeared to be especially effective against glioblastoma lines and the effect could be linked to ferroptosis and inhibition of UBIAD1. In vitro validation of this finding is ongoing.


2021 ◽  
Author(s):  
Hyun Sik Kim ◽  
Young Han Park ◽  
Mi Jung Kwon ◽  
Joon Ho Song ◽  
In Bok Chang

Abstract PurposeThe anti-tumor effect of the beta-adrenergic receptor antagonist propranolol in breast cancer is well known; however, its activity in glioblastoma is not well-evaluated. The Notch-Hes pathway is known to regulate cell differentiation, proliferation, and apoptosis. We investigated the effect of propranolol to human glioblastoma cell lines, and the role of Notch and Hes signaling in this process.MethodsWe performed immunohistochemical staining on 31 surgically resected primary human glioblastoma tissues. We also used glioblastoma cell lines of U87-MG, LN229, and neuroblastoma cell line of SH-SY5Y in this study. The effect of propranolol and isoproterenol on cell proliferation was evaluated using the MTT assay (absorbance 570nm). The impact of propranolol on gene expression (Notch and Hes) was evaluated using real-time (RT) PCR, whereas protein levels of Notch1 and Hes1 were measured using western blotting (WB), simultaneously. Small interfering RNA (siRNA) was used to suppress the Notch gene to investigate its role in the proliferation of glioblastoma.ResultsPropranolol and isoproterenol caused a dose-dependent decrease in cell proliferation (MTT assay). RT-PCR showed an increase in Notch1 and Hes1 expression by propranolol, whereas WB demonstrated increase in Notch1 protein, but a decrease in Hes1 by propranolol. The proliferation of U87-MG and LN229 was not significantly suppressed after transfection with Notch siRNA.ConclusionThese results demonstrated that propranolol suppressed the proliferation of glioblastoma cell lines and neuroblastoma cell line, and Hes1 was more closely involved than Notch1 was in glioblastoma proliferation.


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