scholarly journals The Novel Cyclin-Dependent Kinase Inhibitor Flavopiridol Downregulates Bcl-2 and Induces Growth Arrest and Apoptosis in Chronic B-Cell Leukemia Lines

Blood ◽  
1997 ◽  
Vol 90 (11) ◽  
pp. 4307-4312 ◽  
Author(s):  
Andrea König ◽  
Gary K. Schwartz ◽  
Ramzi M. Mohammad ◽  
Ayad Al-Katib ◽  
Janice L. Gabrilove
Keyword(s):  
Cell Line ◽  
Kinase Inhibitor ◽  
Chromatin Condensation ◽  
Human Tumor ◽  
Trypan Blue Exclusion ◽  
Clinical Phase ◽  
Cellular Effects ◽  
Barr Virus

Flavopiridol is a novel, potent inhibitor of cyclin-dependent kinases (CDK). This synthetic flavone has been reported to exhibit antitumor activity in murine and human tumor cell lines in vitro and in vivo and is currently undergoing clinical phase I evaluation. In the present study, 1 Epstein-Barr virus (EBV)-transformed B-prolymphocytic cell line (JVM-2), 1 EBV-transformed B-CLL cell line (I83CLL), and 1 non-EBV transformed B-CLL cell line (WSU-CLL) were used as targets. Treatment of the cells with flavopiridol (100 nmol/L to 400 nmol/L) led to a marked dose- and time-dependent inhibition of cell growth and survival as determined using trypan blue exclusion. Morphologic analysis showed characteristic apoptotic changes such as chromatin condensation and fragmentation, membrane blebbing, and formation of apoptotic bodies. Furthermore, quantitative assessment of apoptosis-associated DNA strand breaks by in situ TdT labeling showed that a significant number of flavopiridol-treated cells underwent apoptosis. These cellular effects were associated with a significant decrease in bcl-2 expression as observed by Northern and Western blotting. The results showed that flavopiridol downregulates bcl-2 mRNA and bcl-2 protein expression within 24 hours. Genistein and quercetin, two flavonoids that do not inhibit CDKs, did not affect bcl-2 expression. These data suggest an additional mechanism of action of this new flavone which might be useful as an agent in the treatment of chronic lymphoid malignancies.

scholarly journals The Novel Cyclin-Dependent Kinase Inhibitor Flavopiridol Downregulates Bcl-2 and Induces Growth Arrest and Apoptosis in Chronic B-Cell Leukemia Lines

Blood ◽  
1997 ◽  
Vol 90 (11) ◽  
pp. 4307-4312 ◽  
Author(s):  
Andrea König ◽  
Gary K. Schwartz ◽  
Ramzi M. Mohammad ◽  
Ayad Al-Katib ◽  
Janice L. Gabrilove
Keyword(s):  
Cell Line ◽  
Kinase Inhibitor ◽  
Chromatin Condensation ◽  
Human Tumor ◽  
Trypan Blue Exclusion ◽  
Clinical Phase ◽  
Cellular Effects ◽  
Barr Virus

Abstract Flavopiridol is a novel, potent inhibitor of cyclin-dependent kinases (CDK). This synthetic flavone has been reported to exhibit antitumor activity in murine and human tumor cell lines in vitro and in vivo and is currently undergoing clinical phase I evaluation. In the present study, 1 Epstein-Barr virus (EBV)-transformed B-prolymphocytic cell line (JVM-2), 1 EBV-transformed B-CLL cell line (I83CLL), and 1 non-EBV transformed B-CLL cell line (WSU-CLL) were used as targets. Treatment of the cells with flavopiridol (100 nmol/L to 400 nmol/L) led to a marked dose- and time-dependent inhibition of cell growth and survival as determined using trypan blue exclusion. Morphologic analysis showed characteristic apoptotic changes such as chromatin condensation and fragmentation, membrane blebbing, and formation of apoptotic bodies. Furthermore, quantitative assessment of apoptosis-associated DNA strand breaks by in situ TdT labeling showed that a significant number of flavopiridol-treated cells underwent apoptosis. These cellular effects were associated with a significant decrease in bcl-2 expression as observed by Northern and Western blotting. The results showed that flavopiridol downregulates bcl-2 mRNA and bcl-2 protein expression within 24 hours. Genistein and quercetin, two flavonoids that do not inhibit CDKs, did not affect bcl-2 expression. These data suggest an additional mechanism of action of this new flavone which might be useful as an agent in the treatment of chronic lymphoid malignancies.

scholarly journals Rho-kinase inhibitor, fasudil, suppresses glioblastoma cell line progression in vitro and in vivo

2010 ◽  
Vol 9 (11) ◽  
pp. 875-884 ◽  
Author(s):  
Lin Deng ◽  
Gang Li ◽  
Ronghui Li ◽  
Qinglin Liu ◽  
Qiaowei He ◽  
...  
Keyword(s):  
Cell Line ◽  
Kinase Inhibitor ◽  
Rho Kinase ◽  
Glioblastoma Cell Line ◽  
Glioblastoma Cell ◽  
Rho Kinase Inhibitor

scholarly journals Modulated Electro-Hyperthermia Resolves Radioresistance of Panc1 Pancreas Adenocarcinoma and Promotes DNA Damage and Apoptosis In Vitro

2020 ◽  
Vol 21 (14) ◽  
pp. 5100 ◽  
Author(s):  
Gertrud Forika ◽  
Andrea Balogh ◽  
Tamas Vancsik ◽  
Attila Zalatnai ◽  
Gabor Petovari ◽  
...  
Keyword(s):  
Kinase Inhibitor ◽  
Chromatin Condensation ◽  
Annexin V ◽  
Therapy Resistance ◽  
In Vivo Model ◽  
Tumor Growth Inhibition ◽  
Dna Double Strand Breaks ◽  
Cell Fractions

The poor outcome of pancreas ductal adenocarcinomas (PDAC) is frequently linked to therapy resistance. Modulated electro-hyperthermia (mEHT) generated by 13.56 MHz capacitive radiofrequency can induce direct tumor damage and promote chemo- and radiotherapy. Here, we tested the effect of mEHT either alone or in combination with radiotherapy using an in vivo model of Panc1, a KRAS and TP53 mutant, radioresistant PDAC cell line. A single mEHT shot of 60 min induced ~50% loss of viable cells and morphological signs of apoptosis including chromatin condensation, nuclear shrinkage and apoptotic bodies. Most mEHT treatment related effects exceeded those of radiotherapy, and these were further amplified after combining the two modalities. Treatment related apoptosis was confirmed by a significantly elevated number of annexin V single-positive and cleaved/activated caspase-3 positive tumor cells, as well as sub-G1-phase tumor cell fractions. mEHT and mEHT+radioterapy caused the moderate accumulation of γH2AX positive nuclear foci, indicating DNA double-strand breaks and upregulation of the cyclin dependent kinase inhibitor p21waf1 besides the downregulation of Akt signaling. A clonogenic assay revealed that both mono- and combined treatments affected the tumor progenitor/stem cell populations too. In conclusion, mEHT treatment can contribute to tumor growth inhibition and apoptosis induction and resolve radioresistance of Panc1 PDAC cells.

scholarly journals Epstein-Barr virus reprograms human B-lymphocytes immediately in the pre-latent phase of infection

2018 ◽  
Author(s):  
Paulina Mrozek-Gorska ◽  
Alexander Buschle ◽  
Dagmar Pich ◽  
Thomas Schwarzmayr ◽  
Ron Fechtner ◽  
...  
Keyword(s):  
B Lymphocytes ◽  
Metabolic Pathways ◽  
Epstein Barr Virus ◽  
Human Tumor ◽  
Time Resolved ◽  
Barr Virus ◽  
Tumor Virus ◽  
Epstein Barr

AbstractEpstein-Barr virus (EBV) is a human tumor virus and a model of herpesviral latency. The virus efficiently infects resting human B-lymphocytes and induces their continuous proliferation in vitro, which mimics certain aspects of EBV’s oncogenic potential in vivo. This seminal finding was made 50 years ago, but how EBV activates primary human B-lymphocytes and how lymphoblastoid cell lines (LCLs) evolve from the EBV-infected lymphocytes is uncertain. We conducted a systematic time-resolved longitudinal study of cellular functions and transcriptional profiles of newly infected naïve primary B-lymphocytes. EBV reprograms these human cells comprehensively and globally. Rapid and extensive transcriptional changes occur within 24 hours of infection and precede any metabolic and phenotypic changes. Within the next 48 hours, the virus activates the cells, changes their phenotypes with respect to cell size, RNA and protein content and induces metabolic pathways to cope with the increased demand for energy, supporting an efficient cell cycle entry on day three post infection. The transcriptional program that EBV initiates consists of three waves of clearly discernable clusters of cellular genes that peak on day one, two, or three and regulate RNA synthesis, metabolic pathways and cell division, respectively. Upon the onset of cell doublings on day four the cellular transcriptome appears to be completely reprogrammed to support the activated and proliferating cell, but three additional clusters of EBV regulated genes adjust the infected immune cells to fine-tune cell signaling, migration, and immune response pathways, eventually. Our study reveals that more than 98 % of the 13,000 expressed genes in B-lymphocytes are regulated upon infection demonstrating that EBV governs the entire biology of its target cell.

Quiescent Chronic Myelogenous Leukemia (CML) Cells Are Resistant to BCR-ABL Inhibitors but Preferentially Sensitive to BMS-214662, a Farnesyltransferase Inhibitor (FTI) with Unique Quiescent-Cell Selective Cytotoxicity.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1993-1993 ◽  
Author(s):  
Francis Y. Lee ◽  
Mei-Li Wen ◽  
Amy Camuso ◽  
Stephen Castenada ◽  
Krista Fager ◽  
...  
Keyword(s):  
Kinase Inhibitor ◽  
Residual Disease ◽  
Human Tumor ◽  
K562 Cells ◽  
Myelogenous Leukemia ◽  
In Vivo Studies ◽  
Cell Populations ◽  
Progenitor Compartment

Abstract The major concern in the treatment of CML is resistance to the approved agent imatinib mesylate at all stages of disease, most commonly due to mutations in BCR-ABL (but other mechanisms have also been identified). Experimental agents such as dasatinib (BMS-354825), a novel, oral kinase inhibitor that targets BCR-ABL and SRC kinases, or AMN107, which targets BCR-ABL but not SRC, were designed to address all or parts of these mechanisms and are currently under clinical testing. A second concern in CML is persistence of BCR-ABL-positive cells or ‘residual disease’ in the majority of patients on imatinib therapy, including those with complete cytogenetic responses. Bone marrow studies reveal that the residual disease resides at least in part in the primitive CD34+ progenitor compartment, suggesting that imatinib may not be effective against these cell populations (Bhatia et al, Blood101:4701, 2003). Moreover, several imatinib-resistant ABL kinase domain mutations have been detected in CD34+/BCR-ABL+ progenitors (Chu et al, Blood105:2093, 2005), a scenario for eventual disease relapse. A hallmark of CD34+ primitive CML progenitors is quiescence (Elrick et al, Blood105:1862, 2005). We hypothesized that BCR-ABL inhibitors like imatinib may not be effective in killing CML cells in this non-proliferative state. This was tested by comparing cytotoxicity of imatinib or dasatinib in proliferating K562 cells and in cells forced into quiescence by nutrient depletion. Proliferating K562 cells were effectively killed by imatinib (IC50 250–500 nM) and dasatinib (IC50 <1.00 nM). However, cells in quiescent cultures were far more resistant (imatinib IC50 >5000 nM; dasatinib IC50 >12 nM), suggesting that these inhibitors may be less effective in eradicating quiescent CD34+ progenitors. BMS-214662 is a FTI in Phase I clinical development. Unlike many other FTI, BMS-214662 exhibits potent cytotoxic activity against a variety of human tumor cells, and uniquely, its cytotoxicity is highly selective against non-proliferating cancer cells of epithelial origin (Lee et al, Proceedings of the AACR42:260s, 2001). We now demonstrate similar selectivity in K562 CML cells. BMS-214662 was 68-fold more potent in killing quiescent (IC50 = 0.7 uM) than proliferating K562 cells (IC50 = 47.5 uM). Because BCR-ABL inhibitors and BMS-214662 target distinct cell populations (proliferating vs quiescent), there may be a positive therapeutic interaction when these agents are used in combination. In vitro studies in quiescent K562 cultures demonstrated that the combination of BMS-214662 and dasatinib, at concentrations readily achievable in the clinic, produced supra-additive cytotoxicity (% cell kill: dasatinib alone = 0%, BMS-214662 alone = 21%, combination = 71%). In vivo studies in K562 xenografts implanted SC in mice also showed that the combination of BMS-214662 and dasatinib produced a superior anti-leukemic activity than either dasatinib alone (P=0.0157) or BMS-214662 alone (P=0.0002). These results highlight the potential utility of BMS-214662 for targeting the quiescent progenitor compartment which, in combination with targeted agents such as dasatinib, address both BCR-ABL-dependent and -independent mechanisms of resistance, and may produce more durable responses and suppress the emergence of resistance.

scholarly journals Epstein–Barr virus reprograms human B lymphocytes immediately in the prelatent phase of infection

2019 ◽  
Vol 116 (32) ◽  
pp. 16046-16055 ◽  
Author(s):  
Paulina Mrozek-Gorska ◽  
Alexander Buschle ◽  
Dagmar Pich ◽  
Thomas Schwarzmayr ◽  
Ron Fechtner ◽  
...  
Keyword(s):  
B Lymphocytes ◽  
Metabolic Pathways ◽  
Epstein Barr Virus ◽  
Plasma Cells ◽  
Human Tumor ◽  
Proliferating Cells ◽  
Barr Virus ◽  
Epstein Barr

Epstein–Barr virus (EBV) is a human tumor virus and a model of herpesviral latency. The virus efficiently infects resting human B lymphocytes and induces their continuous proliferation in vitro, which mimics certain aspects of EBV’s oncogenic potential in vivo. How lymphoblastoid cell lines (LCLs) evolve from the infected lymphocytes is uncertain. We conducted a systematic time-resolved longitudinal study of cellular functions and transcriptional profiles of newly infected naïve primary B lymphocytes. EBV reprograms the cells comprehensively and globally. Rapid and extensive transcriptional changes occur within 24 h and precede any metabolic and phenotypic changes. Within 72 h, the virus activates the cells, changes their phenotypes with respect to cell size, RNA, and protein content, and induces metabolic pathways to cope with the increased demand for energy, supporting an efficient cell cycle entry on day 3 postinfection. The transcriptional program that EBV initiates consists of 3 waves of clearly discernable clusters of cellular genes that peak on day 2, 3, or 4 and regulate RNA synthesis, metabolic pathways, and cell division, respectively. Upon onset of cell doublings on day 4, the cellular transcriptome appears to be completely reprogrammed to support the proliferating cells, but 3 additional clusters of EBV-regulated genes fine-tune cell signaling, migration, and immune response pathways, eventually. Our study reveals that more than 11,000 genes are regulated upon EBV infection as naïve B cells exit quiescence to enter a germinal center-like differentiation program, which culminates in immortalized, proliferating cells that partially resemble plasmablasts and early plasma cells.

scholarly journals Caspases switch off m6A RNA modification pathway to reactivate a ubiquitous human tumor virus

2020 ◽  
Author(s):  
Kun Zhang ◽  
Yucheng Zhang ◽  
Jun Wan ◽  
Renfeng Li
Keyword(s):  
Human Tumor ◽  
Feedback Regulation ◽  
Rna Modification ◽  
Barr Virus ◽  
Multiple Components ◽  
Tumor Virus ◽  
Epstein Barr ◽  
Caspase Substrate

AbstractThe methylation of RNA at the N6 position of adenosine (m6A) orchestrates multiple biological processes to control development, differentiation, and cell cycle, as well as various aspects of the virus life cycle. How the m6A RNA modification pathway is regulated to finely tune these processes remains poorly understood. Here, we discovered the m6A reader YTHDF2 as a caspase substrate via proteome-wide prediction, followed by in vitro and in vivo validations. We further demonstrated that cleavage-resistant YTHDF2 blocks, while cleavage-mimicking YTHDF2 fragments promote, the replication of a common human oncogenic virus, Epstein-Barr virus (EBV). Intriguingly, our study revealed a feedback regulation between YTHDF2 and caspase-8 via m6A modification of CASP8 mRNA and YTHDF2 cleavage during EBV replication. Further, we discovered that caspases cleave multiple components within the m6A RNA modification pathway to benefit EBV replication. Together, our study establishes that caspase disarming of the m6A RNA modification machinery fosters EBV reactivation.

scholarly journals In vitro and In vivo Radiation Sensitization of Human Tumor Cells by a Novel Checkpoint Kinase Inhibitor, AZD7762

2010 ◽  
Vol 16 (7) ◽  
pp. 2076-2084 ◽  
Author(s):  
James B. Mitchell ◽  
Rajani Choudhuri ◽  
Kristin Fabre ◽  
Anastasia L. Sowers ◽  
Deborah Citrin ◽  
...  
Keyword(s):  
Tumor Cells ◽  
Kinase Inhibitor ◽  
Human Tumor ◽  
Human Tumor Cells ◽  
Checkpoint Kinase ◽  
Radiation Sensitization ◽  
Checkpoint Kinase Inhibitor

Ultrastructural Correlations between Clonal Human Tumor Colonies and in Vivo Neoplasms

1982 ◽  
Vol 40 ◽  
pp. 210-211
Author(s):  
M.J. Murphy ◽  
R.R. Price ◽  
J.C. Sloman
Keyword(s):  
Cultured Cells ◽  
Human Tumor ◽  
Cell Type ◽  
Tumor Mass ◽  
Initial Cell ◽  
Cloning Assay ◽  
Human Tumor Cloning ◽  
The Relationship

The in vitro human tumor cloning assay originally described by Salmon and Hamburger has been applied recently to the investigation of differential anti-tumor drug sensitivities over a broad range of human neoplasms. A major problem in the acceptance of this technique has been the question of the relationship between the cultured cells and the original patient tumor, i.e., whether the colonies that develop derive from the neoplasm or from some other cell type within the initial cell population. A study of the ultrastructural morphology of the cultured cells vs. patient tumor has therefore been undertaken to resolve this question. Direct correlation was assured by division of a common tumor mass at surgical resection, one biopsy being fixed for TEM studies, the second being rapidly transported to the laboratory for culture.

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