Serum Starvation Induced Cell Cycle Synchronization Facilitates Human Somatic Cells Reprogramming

Chen, Mengfei; Huang, Jingjing; Yang, Xiaofeng; Liu, Bingqian; Zhang, Weizhong; Huang, Li; Deng, Fei; Ma, Jian; Bai, Yujing; Lu, Rong; Huang, Bing; Gao, Qianying; Zhuo, Yehong; Ge, Junbo

doi:10.1371/journal.pone.0028203

Cited by 112 publications

(94 citation statements)

References 44 publications

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“…This is in agreement with previous reports of CDK4/6 inhibition leading to sequential emptying of the cell-cycle phases downstream of the restriction point, followed by an increasing spread of cells across phases upon release from synchronization (11,24,25). It should be pointed out, however, that using the same rate constant between each transit compartment would not have accounted for the different duration of each cell-cycle phase (17,26,27).…”

Section: Discussionsupporting

confidence: 92%

Semi-Mechanistic Pharmacokinetic/Pharmacodynamic Modeling of the Antitumor Activity of LY2835219, a New Cyclin-Dependent Kinase 4/6 Inhibitor, in Mice Bearing Human Tumor Xenografts

Tate

Cai

Ajamie

et al. 2014

Clinical Cancer Research

116

104

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Purpose: Selective inhibition of cyclin-dependent kinases 4 and 6 (CDK4/6) represents a promising therapeutic strategy. However, despite documented evidence of clinical activity, limited information is available on the optimal dosing strategy of CDK4/6 inhibitors. Here, we present an integrated semimechanistic pharmacokinetic/pharmacodynamic model to characterize the quantitative pharmacology of LY2835219, a CDK4/6 inhibitor, in xenograft tumors.Experimental Design: LY2835219 plasma concentrations were connected to CDK4/6 inhibition and cell-cycle arrest in colo-205 human colorectal xenografts by incorporating the biomarkers, phospho-(ser780)-Rb, topoisomerase II a, and phosphohistone H3, into a precursor-dependent transit compartment model. This biomarker model was then connected to tumor growth inhibition (TGI) by: (i) relating the rate of tumor growth to mitotic cell density, and (ii) incorporating a concentration-dependent mixed cytostatic/ cytotoxic effect driving quiescence and cell death at high doses. Model validation was evaluated by predicting LY2835219-mediated antitumor effect in A375 human melanoma xenografts.Results: The model successfully described LY2835219-mediated CDK4/6 inhibition, cell-cycle arrest, and TGI in colo-205, and was validated in A375. The model also demonstrated that a chronic dosing strategy achieving minimum steady-state trough plasma concentrations of 200 ng/mL is required to maintain durable cell-cycle arrest. Quiescence and cell death can be induced by further increasing LY2835219 plasma concentrations.Conclusions: Our model provides mechanistic insight into the quantitative pharmacology of LY2835219 and supports the therapeutic dose and chronic dosing strategy currently adopted in clinical studies.

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Section: Discussionsupporting

confidence: 92%

Semi-Mechanistic Pharmacokinetic/Pharmacodynamic Modeling of the Antitumor Activity of LY2835219, a New Cyclin-Dependent Kinase 4/6 Inhibitor, in Mice Bearing Human Tumor Xenografts

Tate

Cai

Ajamie

et al. 2014

Clinical Cancer Research

116

104

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“…1B). These findings are in agreement with those of a previous study, which found that the highest proportion of cells were in S phase after 20 h of refeeding of serum (27). While the actual percentage of cells in each phase was different by using immunofluorescence, our analysis of the cell cycle using the S-phase-specific marker BrdU (28) showed a similar pattern, with the highest percentage of cells being in S phase after 16 h.…”

Section: Discussionsupporting

confidence: 92%

The Periodontal Pathogen Porphyromonas gingivalis Preferentially Interacts with Oral Epithelial Cells in S Phase of the Cell Cycle

2016

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Porphyromonas gingivalis, a key periodontal pathogen, is capable of invading a variety of cells, including oral keratinocytes, by exploiting host cell receptors, including alpha-5 beta-1 (␣5␤1) integrin. Previous studies have shown that P. gingivalis accelerates the cell cycle and prevents apoptosis of host cells, but it is not known whether the cell cycle phases influence bacterium-cell interactions. The cell cycle distribution of oral keratinocytes was characterized by flow cytometry and BrdU (5-bromo-2-deoxyuridine) staining following synchronization of cultures by serum starvation. The effect of cell cycle phases on P. gingivalis invasion was measured by using antibiotic protection assays and flow cytometry, and these results were correlated with gene and surface expression levels of ␣5 integrin and urokinase plasminogen activator receptor (uPAR). There was a positive correlation (R ‫؍‬ 0.98) between the number of cells in S phase and P. gingivalis invasion, the organism was more highly associated with cells in S phase than with cells in G 2 and G 1 phases, and S-phase cells contained 10 times more bacteria than did cells that were not in S phase. Our findings also show that ␣5 integrin, but not uPAR, was positively correlated with cells in S phase, which is consistent with previous reports indicating that P. gingivalis invasion of cells is mediated by ␣5 integrin. This study shows for the first time that P. gingivalis preferentially associates with and invades cells in the S phase of the cell cycle. The mechanism of targeting stable dividing cells may have implications for the treatment of periodontal diseases and may partly explain the persistence of this organism at subgingival sites. Porphyromonas gingivalis, a Gram-negative anaerobic bacillus, is one of the major putative periodontal pathogens associated with the initiation and progression of chronic periodontal diseases (1). P. gingivalis has the ability to invade a variety of host cells, including oral keratinocytes (2), through numerous surface-associated virulence factors such as fimbriae (3), hemagglutinins (4), and gingipain proteases (5). The invasion strategy provides a considerable value for bacterium survival, as it could protect periodontal pathogens from host defense mechanisms and assist in their persistence within a site of infection, leading to continuous periodontal inflammation. P. gingivalis has the ability to invade gingival epithelial cells, reside in the cell cytoplasm, remain viable, replicate, and then spread to neighboring epithelial cells (6). However, not all epithelial cells in a population are invaded equally, suggesting that there may be differences between cells in their susceptibility to P. gingivalis invasion, but the reason for this is unclear.Host-bacterium interactions play a dynamic role for the establishment of bacteria within the site of infection. The cohabitation of bacteria with host cells is mediated by several host cell receptors, which facilitate bacterium attachment to host cells and resultant invasion (7). ␣...

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“…All experiments were performed using media containing 1% serum following 24 h of serum starvation. This procedure has been effective for the synchronization of cells in the G0 phase in cell cycle studies (22,23).…”

Section: Methodsmentioning

confidence: 99%

Sinomenine, a COX-2 inhibitor, induces cell cycle arrest and inhibits growth of human colon carcinoma cells in vitro and in vivo

et al. 2015

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Abstract. Certain non-steroidal anti-inflammatory drugs may possess anti-tumorigenic effects in certain cancer cell types. Sinomenine (SIN) is an alkaloid from Sinomenium acutum, a Chinese medicinal plant that inhibits inflammatory reactions and that has been used in the treatment of neuralgia and rheumatic diseases. In this study, we investigated the anticancer effects of SIN against colorectal cancer in vitro and in vivo, as well as the underlying mechanisms. The effects of SIN on proliferation, cell cycle progression and cyclooxygenase (COX)-2 expression were examined in human colorectal cancer-derived SW1116 cells. The in vivo effects of SIN were examined in a model of SW1116 tumor xenograft growth in athymic nude mice. Changes in COX-2 expression induced by the biological effects of SIN were analyzed by western blot analysis. The effects of SIN treatment on G1 phase cell cycle regulators in xenografts were analyzed by immunohistochemistry. Our findings demonstrate that SIN inhibits the proliferation of SW1116 cells by promoting their accumulation in the G1 phase, with concomitant suppression of COX-2 expression. Time-and dose-dependent inhibition of tumor growth and reduced toxicity were observed in nude mice administered daily intraperitoneal injections of SIN at doses of 25, 50 and 100 mg/kg. SIN-treated tumors also exhibited reduced COX-2 expression, a marked increase in Cip1/p21 protein levels and a decrease in the levels of cyclin D1 and cyclin E. SIN may be an effective chemopreventive agent against colorectal cancer. The growth inhibitory properties of SIN against colorectal cancer may be mediated via a COX-2 inhibitory effect and cell cycle arrest in the G1 phase.

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Serum Starvation Induced Cell Cycle Synchronization Facilitates Human Somatic Cells Reprogramming

Cited by 112 publications

References 44 publications

Semi-Mechanistic Pharmacokinetic/Pharmacodynamic Modeling of the Antitumor Activity of LY2835219, a New Cyclin-Dependent Kinase 4/6 Inhibitor, in Mice Bearing Human Tumor Xenografts

Semi-Mechanistic Pharmacokinetic/Pharmacodynamic Modeling of the Antitumor Activity of LY2835219, a New Cyclin-Dependent Kinase 4/6 Inhibitor, in Mice Bearing Human Tumor Xenografts

The Periodontal Pathogen Porphyromonas gingivalis Preferentially Interacts with Oral Epithelial Cells in S Phase of the Cell Cycle

Sinomenine, a COX-2 inhibitor, induces cell cycle arrest and inhibits growth of human colon carcinoma cells in vitro and in vivo

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