scholarly journals The cell cycle–apoptosis connection revisited in the adult brain

2005 ◽  
Vol 171 (4) ◽  
pp. 641-650 ◽  
Author(s):  
Sylvian Bauer ◽  
Paul H. Patterson
Keyword(s):  
Cell Cycle ◽  
Dna Repair ◽  
Dna Synthesis ◽  
Adult Neurogenesis ◽  
Adult Brain ◽  
Brdu Incorporation ◽  
High Dose ◽  
Brdu Labeling ◽  
Postmitotic Neurons

Adult neurogenesis is studied in vivo using thymidine analogues such as bromodeoxyuridine (BrdU) to label DNA synthesis during the S phase of the cell cycle. However, BrdU may also label DNA synthesis events not directly related to cell proliferation, such as DNA repair and/or abortive reentry into the cell cycle, which can occur as part of an apoptotic process in postmitotic neurons. In this study, we used three well-characterized models of injury-induced neuronal apoptosis and the combined visualization of cell birth (BrdU labeling) and death (Tdt-mediated dUTP-biotin nick end labeling) to investigate the specificity of BrdU incorporation in the adult mouse brain in vivo. We present evidence that BrdU is not significantly incorporated during DNA repair and that labeling is not detected in vulnerable or dying postmitotic neurons, even when a high dose of BrdU is directly infused into the brain. These findings have important implications for a controversy surrounding adult neurogenesis: the connection between cell cycle reactivation and apoptosis of terminally differentiated neurons.

scholarly journals A Novel Benzopyrane Derivative Targeting Cancer Cell Metabolic and Survival Pathways

Cancers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2840
Author(s):  
Dana M. Zaher ◽  
Wafaa S. Ramadan ◽  
Raafat El-Awady ◽  
Hany A. Omar ◽  
Fatema Hersi ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Cancer Cell ◽  
Xenograft Model ◽  
Mitochondrial Metabolism ◽  
High Dose ◽  
Anticancer Effect ◽  
Safety Margins ◽  
Wide Range

(1) Background: Today, the discovery of novel anticancer agents with multitarget effects and high safety margins represents a high challenge. Drug discovery efforts indicated that benzopyrane scaffolds possess a wide range of pharmacological activities. This spurs on building a skeletally diverse library of benzopyranes to identify an anticancer lead drug candidate. Here, we aim to characterize the anticancer effect of a novel benzopyrane derivative, aiming to develop a promising clinical anticancer candidate. (2) Methods: The anticancer effect of SIMR1281 against a panel of cancer cell lines was tested. In vitro assays were performed to determine the effect of SIMR1281 on GSHR, TrxR, mitochondrial metabolism, DNA damage, cell cycle progression, and the induction of apoptosis. Additionally, SIMR1281 was evaluated in vivo for its safety and in a xenograft mice model. (3) Results: SIMR1281 strongly inhibits GSHR while it moderately inhibits TrxR and modulates the mitochondrial metabolism. SIMR1281 inhibits the cell proliferation of various cancers. The antiproliferative activity of SIMR1281 was mediated through the induction of DNA damage, perturbations in the cell cycle, and the inactivation of Ras/ERK and PI3K/Akt pathways. Furthermore, SIMR1281 induced apoptosis and attenuated cell survival machinery. In addition, SIMR1281 reduced the tumor volume in a xenograft model while maintaining a high in vivo safety profile at a high dose. (4) Conclusions: Our findings demonstrate the anticancer multitarget effect of SIMR1281, including the dual inhibition of glutathione and thioredoxin reductases. These findings support the development of SIMR1281 in preclinical and clinical settings, as it represents a potential lead compound for the treatment of cancer.

scholarly journals The Schizosaccharomyces pombe rad11+ gene encodes the large subunit of replication protein A.

1997 ◽  
Vol 17 (5) ◽  
pp. 2381-2390 ◽  
Author(s):  
A E Parker ◽  
R K Clyne ◽  
A M Carr ◽  
T J Kelly
Keyword(s):  
Dna Repair ◽  
Dna Synthesis ◽  
Schizosaccharomyces Pombe ◽  
Excision Repair ◽  
Protein A ◽  
Simian Virus 40 ◽  
Replication Protein A ◽  
S Phase ◽  
Replication Protein

Replication protein A (RPA) is a heterotrimeric single-stranded DNA-binding protein present in all eukaryotes. In vitro studies have implicated RPA in simian virus 40 DNA synthesis and nucleotide excision repair, but little direct information is available about the in vivo roles of the protein. We report here the cloning of the largest subunit of RPA (rpa1+) from the fission yeast Schizosaccharomyces pombe. The rpa1+ gene is essential for viability and is expressed specifically at S phase of the cell cycle. Genetic analysis revealed that rpa1+ is the locus of the S. pombe radiation-sensitive mutation rad11. The rad11 allele exhibits pleiotropic effects consistent with an in vivo role for RPA in both DNA repair and DNA synthesis. The mutant is sensitive to both UV and ionizing radiation but is not defective in the DNA damage-dependent checkpoint, consistent with the hypothesis that RPA is part of the enzymatic machinery of DNA repair. When incubated in hydroxyurea, rad11 cells initially arrest with a 1C DNA content but then lose viability coincident with reentry into S phase, suggesting that DNA synthesis is aberrant under these conditions. A significant fraction of the mutant cells subsequently undergo inappropriate mitosis in the presence of hydroxyurea, indicating that RPA also plays a role in the checkpoint mechanism that monitors the completion of S phase. We propose that RPA is required to maintain the integrity of replication complexes when DNA replication is blocked. We further suggest that the rad11 mutation leads to the premature breakdown of such complexes, thereby preventing recovery from the hydroxyurea arrest and eliminating a signal recognized by the S-phase checkpoint mechanism.

Expression of Cell Cycle Proteins P21 waf1/Cip1 , P27 kip1 , Cyclin D1 and CDK4 in Blood Vessels of Angiotensin II-Infused Rats. Role of AT 1 Receptors.

Hypertension ◽  
2000 ◽  
Vol 36 (suppl_1) ◽  
pp. 707-707
Author(s):  
Quy N Diep ◽  
Mohammed El Mabrouk ◽  
Rhian M Touyz ◽  
Ernesto L Schiffrin
Keyword(s):  
Cell Cycle ◽  
Angiotensin Ii ◽  
Dna Synthesis ◽  
Cyclin D1 ◽  
Blood Vessels ◽  
Thymidine Incorporation ◽  
Mesenteric Arteries ◽  
Ang Ii

P79 Angiotensin II (Ang II) is an important modulator of cell growth via AT 1 receptors, as demonstrated both in vivo and in vitro . Here, we investigated the role of different proteins involved in the cell cycle, including cyclin D1, cyclin-dependent kinase 4 (cdk4) and cdk inhibitors p21 and p27 in blood vessels of Ang II-infused rats and the effect therein of the AT 1 receptor antagonist losartan. Male Sprague Dawley rats were infused for 7 days with Ang II (120 ng/kg/min s.c.) and/or treated with losartan (10 mg/kg/day orally). DNA synthesis in mesenteric arteries was evaluated by radiolabeled 3 H-thymidine incorporation. The expression of p21, p27, cyclin D1, cdk4 and E2F, which play critical roles during G1-phase of the cell cycle process, was examined by Western blot analysis. Tail cuff systolic blood pressure (mmHg) was elevated (p<0.05, n=9) in Ang II-infused rats (161.3±8.2) vs. controls (110.1±5.3) and normalized by losartan (104.4±3.2). Radiolabeled 3 H-thymidine incorporation (cpm/100 μg DNA) showed that Ang II-infusion significantly increased DNA synthesis (152±5 vs. 102±6, p<0.05). Expression of p21 and p27 was significantly decreased in the Ang II group to 23.2±10.4% and 10.3±5.3% of controls, respectively, whereas expression of cyclin D1 and cdk4 was significantly increased in the Ang II group to 213.7±8% and 263.6±37% of controls, respectively. These effects induced by Ang II infusion was normalized in the presence of losartan. Ang II had no effect on the expression of E2F. Thus, when AT 1 receptors are stimulated in vivo , DNA synthesis is enhanced in blood vessels by activation of cyclin D1 and cdk4. Reduction in cell cycle kinase inhibitors p21 and p27 may contribute to activation of growth induced by in vivo AT 1 receptor stimulation.

Polymorphisms in XRCC1, XRCC3, and CCND1 and Survival After Treatment for Metastatic Breast Cancer

2006 ◽  
Vol 24 (36) ◽  
pp. 5645-5651 ◽  
Author(s):  
Mary A. Bewick ◽  
Michael S.C. Conlon ◽  
Robert M. Lafrenie
Keyword(s):  
Breast Cancer ◽  
Cell Cycle ◽  
Dna Repair ◽  
Metastatic Breast Cancer ◽  
Bone Metastases ◽  
Cell Cycle Control ◽  
Multivariable Analysis ◽  
Metastatic Breast ◽  
High Dose ◽  
Cancer Specific Survival

Purpose Single nucleotide polymorphisms (SNPs) in DNA repair and cell cycle control genes may alter protein function and therefore the efficacy of DNA damaging chemotherapy. We retrospectively evaluated the association of SNPs in DNA repair genes, XRCC1-01 (Arg399Gln) and XRCC3-01 (Thr241Met), and a cell cycle control gene, CCND1-02 (A870G), with progression-free survival (PFS) and breast cancer specific survival (BCSS) in patients with metastatic breast cancer (MBC). Patients and Methods SNPs in 95 patients with MBC enrolled onto one of five prospective clinical trials of high-dose chemotherapy and autologous stem-cell transplantation were evaluated using genotyping assays. Results For XRCC1-01, the hazard ratio (HR) for BCSS was 2.8 (95% CI, 1.60 to 5.00) and the HR for PFS was 2.0 (95%CI, 1.12 to 3.43). For XRCC3-01, the HR for BCSS was 2.0 (95%CI, 1.12 to 3.70) and the HR for PFS was 2.0 (95%CI, 1.09 to 3.59). For CCND1-02, the HR for BCSS was 1.8 (95%CI, 1.12 to 2.78) and the HR for PFS was 1.8 (95%CI, 1.15 to 2.85). Patients carrying one variant genotype (HR, 1.7; 95%CI, 1.07 to 2.82) or combinations of any two variant genotypes (HR, 4.7; 95% CI, 2.41 to 8.94) had significantly poorer BCSS compared with patients carrying zero variants. In multivariable analysis, XRCC1-01, presence of liver metastases, and bone metastases independently predicted BCSS. Combinations of any two variant genotypes were stronger independent predictors of BCSS and PFS than the presence of liver or bone metastases. Conclusion XRCC1-01, XRCC3-01, and CCND1-01 may be predictive of survival outcome in patients with MBC treated with DNA damaging chemotherapy.

Alterations in the cell cycle of mouse cumulus granulosa cells during expansion and mucification in vivo and in vitro

1996 ◽  
Vol 8 (6) ◽  
pp. 935 ◽  
Author(s):  
AW Schuetz ◽  
DG Whittingham ◽  
R Snowden
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Granulosa Cells ◽  
Dna Content ◽  
Cumulus Cell ◽  
Cumulus Cells ◽  
Ovarian Follicles ◽  
S Phase

The cell cycle characteristics of mouse cumulus granulosa cells were determined before, during and following their expansion and mucification in vivo and in vitro. Cumulus-oocyte complexes (COC) were recovered from ovarian follicles or oviducts of prepubertal mice previously injected with pregnant mare serum gonadotrophin (PMSG) or a mixture of PMSG and human chorionic gonadotrophin (PMSG+hCG) to synchronize follicle differentiation and ovulation. Cell cycle parameters were determined by monitoring DNA content of cumulus cell nuclei, collected under rigorously controlled conditions, by flow cytometry. The proportion of cumulus cells in three cell cycle-related populations (G0/G1; S; G2/M) was calculated before and after exposure to various experimental conditions in vivo or in vitro. About 30% of cumulus cells recovered from undifferentiated (compact) COC isolated 43-45 h after PMSG injections were in S phase and 63% were in G0/G1 (2C DNA content). Less than 10% of the cells were in the G2/M population. Cell cycle profiles of cumulus cells recovered from mucified COC (oviducal) after PMSG+hCG-induced ovulation varied markedly from those collected before hCG injection and were characterized by the relative absence of S-phase cells and an increased proportion of cells in G0/G1. Cell cycle profiles of cumulus cells collected from mucified COC recovered from mouse ovarian follicles before ovulation (9-10 h after hCG) were also characterized by loss of S-phase cells and an increased G0/G1 population. Results suggest that changes in cell cycle parameters in vivo are primarily mediated in response to physiological changes that occur in the intrafollicular environment initiated by the ovulatory stimulus. A similar lack of S-phase cells was observed in mucified cumulus cells collected 24 h after exposure in vitro of compact COC to dibutyryl cyclic adenosine monophosphate (DBcAMP), follicle-stimulating hormone or epidermal growth factor (EGF). Additionally, the proportion of cumulus cells in G2/M was enhanced in COC exposed to DBcAMP, suggesting that cell division was inhibited under these conditions. Thus, both the G1-->S-phase and G2-->M-phase transitions in the cell cycle appear to be amenable to physiological regulation. Time course studies revealed dose-dependent changes in morphology occurred within 6 h of exposure in vitro of COC to EGF or DBcAMP. Results suggest that the disappearance of the S-phase population is a consequence of a decline in the number of cells beginning DNA synthesis and exit of cells from the S phase following completion of DNA synthesis. Furthermore, loss of proliferative activity in cumulus cells appears to be closely associated with COC expansion and mucification, whether induced under physiological conditions in vivo or in response to a range of hormonal stimuli in vitro. The observations indicate that several signal-transducing pathways mediate changes in cell cycle parameters during cumulus cell differentiation.

In-Vitro and in-Vivo Synergistic Effect of Melphalan and Dual DNA Repair Inhibition in Multiple Myeloma

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3301-3301
Author(s):  
Pritesh R. Patel ◽  
Annie L. Oh ◽  
Vitalyi Senyuk ◽  
Dolores Mahmud ◽  
Nadim Mahmud ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Dna Repair ◽  
Combination Index ◽  
Fold Increase ◽  
High Dose ◽  
Myeloma Cells ◽  
Synergistic Cytotoxicity ◽  
Significant Difference

Abstract High dose melphalan is commonly used in patients with multiple myeloma (MM). Resistance to melphalan has been linked to the ability to repair DNA damage. To test whether DNA repair inhibitors overcome resistance to melphalan and and also have a direct anti-MM effect, we tested MM cell lines RPMI8226 and U266 in-vitro and in-vivo, using a NOD/SCID/ gamma null (NSG) xenograft model. RPMI8226 and U266 cells were initially treated in-vitro with the PARP inhibitor ABT-888. Using a proliferative assay, myeloma cells appeared sensitive to ABT-888 with low GI50 values (8.7μM for RPMI8226 cells, 49μM for U266 cells) and increased γH2AX foci, which persisted at 24 hours after treatment. This was confirmed in methycellulose colony assay where ABT-888 treatment reduced RPMI8226 colonies by 35% (p=0.002). Next we showed synergistic cytotoxicity between ABT-888 and melphalan. In both RPMI8226 and U266 cells strong synergy was displayed with a combination index (CI) less than 1 in proliferative assays (CI 0.5 and 0.3 at 50% proliferation respectively). Combination ABT-888 and melphalan treated cells underwent accelerated senescence compared to cells treated by melphalan alone (27% versus 51% βGal+ staining at 24 hours, p=0.02). This was confirmed by upregulation of senescence related genes p16 (1.6 fold increase) and p21 (1.5 fold increase). We did not find significant difference in apoptosis by Annexin V/ PI staining. Given that increased non-homologous end joining (NHEJ) activity has been shown to lead to resistance to melphalan, we tested whether an inhibitor of NHEJ could be synergistic with PARP inhibition and melphalan. Treatment with the DNA-PK inhibitor NU7026 at 10μM in addition to ABT-888 at 4μM resulted in 46% reduction in proliferation in RPMI8226 cells and 52% in U266 cells. When used in combination with melphalan chemotherapy, the dual DNA repair inhibitor therapy showed marked synergy in RPMI8226 cells with a combination index of 0.39. Finally we tested the ability of the combination of ABT-888 and melphalan to treat myeloma in-vivo. NSG mice were injected via tail vein with 5x106 RPMI8226 cells. Control (untreated) mice subsequently developed myeloma infiltrating the marrow, spleen and axial skeleton, with hind limb paralysis occurring at a median of 42 days. Treated mice received intraperitoneal injections of ABT-888 (3 times a week), or melphalan (weekly) or a combination of both agents starting on day 28 post-injection of MM cells for a total of 3 weeks. Using ABT-888, melphalan and a combination of both agents, median survival of mice was progressively prolonged (44 vs. 67 vs. 107 days, respectively) (p=0.02). Here we show that PARP and DNA-PK inhibition synergizes with melphalan in myeloma cells lines, providing a rationale for the addition of these agents to conditioning chemotherapy. In addition, we also show a direct anti-myeloma activity of these agents without the use of alkylator chemotherapy. Disclosures No relevant conflicts of interest to declare.

Differential response of prostate cancer cells to ionizing radiation: The RB status.

2012 ◽  
Vol 30 (5_suppl) ◽  
pp. 106-106
Author(s):  
Robert Benjamin Den ◽  
Steve Ciment ◽  
Ankur Sharma ◽  
Hestia Mellert ◽  
Steven McMahon ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Cell Cycle ◽  
Dna Damage ◽  
Dna Repair ◽  
Ionizing Radiation ◽  
Cell Survival ◽  
Hormone Sensitive ◽  
Clonogenic Cell ◽  
Castrate Resistant

106 Background: Prostate cancer is the most frequently diagnosed malignancy and the second leading cause of cancer death in U.S. men. The retinoblastoma tumor suppressor protein, RB, plays a critical role in cell cycle regulation and loss of RB has been observed in 25-30% of prostate cancers. We have previously shown that RB loss results in a castrate resistant phenotype, however the consequences of RB status with regard to radiation response are unknown. We hypothesized that RB loss would downregulate the G1-S cell cycle checkpoint arrest normally induced by irradiation, inhibit DNA repair, and subsequently sensitize cells to ionizing radiation. Methods: Experimental work was performed with multiple isogenic prostate cancer cell lines (hormone sensitive: LNCaP and LAP-C4 cells and hormone resistant C42, 22Rv1 cells; stable knockdown of RB using shRNA). Gamma H2AX assays were used to quantitate DNA damage and PARP cleavage and Caspase 3 were used to quantitate apoptosis. FACS analysis with BrdU was used to assess the cell cycle. Cell survival was measured using the clonogenic cell survival assay. In vivo work was performed in nude mice with tumor xenografts. Results: We observed that loss of RB increased radioresponsiveness in both transient and clonogenic cell survival assays in both hormone sensitive and castrate resistant cell lines (p<0.05). Cell death was not mediated through increased apoptosis nor was perturbations in cell cycle noted. However, loss of RB effected DNA repair as measured by gamma H2AX staining as well as cellular senescence. In vivo xenografts of the RB deficient tumors exhibited diminished tumor mass, lower PSA kinetics and decreased tumor growth after treatment with single fraction of ionizing radiation in comparison to RB intact tumors (p<0.05). Conclusions: Loss of RB results in a differential response to ionizing radiation. Isogenic cells with RB knockdown are more sensitive to DNA damage and result in reduced cell survival. The underlying mechanism appears to be related to DNA damage repair and cellular senescence.

scholarly journals Insulin Stimulates Goose Liver Cell Growth by Activating PI3K-AKT-mTOR Signal Pathway

2016 ◽  
Vol 38 (2) ◽  
pp. 558-570 ◽  
Author(s):  
Chunchun Han ◽  
Shouhai Wei ◽  
Qi Song ◽  
Fang He ◽  
Xiangping Xiong ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Dna Synthesis ◽  
Protein Content ◽  
Mrna Level ◽  
Signal Pathway ◽  
Mtor Pathway ◽  
Brdu Incorporation ◽  
Primary Hepatocytes

Background/Aims: Recent studies have suggested a crucial role for PI3K-Akt-mTOR pathway in regulating cell proliferation, so we hypothesize that insulin acts goose hepatocellular growth by PI3K-Akt-mTOR signal pathway. Because the physiological status of liver cells in vitro is different from that in vivo, a simplified cell model in vitro was established. Methods: Goose primary hepatocytes were isolated and incubated in either no addition as a control or insulin or PI3K-Akt-mTOR pathway inhibitors or co-treatment with glucose and PI3K-Akt-mTOR pathway inhibitors; Then, cell DNA synthesis and cell cycle analysis were detected by BrdU-incorporation Assay and Flow cytometric analysis; the mRNA expression and protein expression of factors involved in the cell cycle were determined by Real-Time RT-PCR, ELISA, and western blot. Results: Here we first showed that insulin evidently increased the cell DNA synthesis, the mRNA level and protein content of factors involved in the cell proliferation of goose primary hepatocytes. Meanwhile, insulin evidently increased the mRNA level and protein content of factors involved in PI3K-Akt-mTOR pathway. However, the up-regulation of insulin on cell proliferation was decreased significantly by the inhibitors of PBK-Akt-mTOR pathway, LY294002, rapamycin or NVP-BEZ235. Conclusion: These findings suggest that PI3K-Akt-mTOR pathway plays an essential role in insulin-regulated cell proliferation of goose hepatocyte.

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