Reversible Regulation of Cell Cycle-Related Genes by Epigallocatechin Gallate for Hibernation of Neonatal Human Tarsal Fibroblasts

EGCG improves recombinant protein productivity in Chinese hamster ovary cell cultures via cell proliferation control

Chinese hamster ovary cell lines are good manufacturing practice-certified host cells and are widely used in the field of biotechnology to produce therapeutic antibodies. Recombinant protein productivity in cells is strongly associated with cell growth. To control cell proliferation, many approaches have previously been tested including: genetic engineering, chemical additives such as cell cycle inhibitors, and temperature shift of the culture. To be widely adopted in the biopharmaceutical industry, the culture methods should be simple, uniform and safe. To this end, we examined the use a natural compound to improve the production capacity. In this study, we focused on the antioxidants, catechin polyphenols, which are found in green tea, for cell proliferation control strategies. (-)-Epigallocatechin-3-gallate (EGCG), the major catechin that induces G0/G1 cell cycle arrest, was investigated for its effect on recombinant protein production. Adding EGCG to the cell culture media resulted in slower cellular growth and longer cell longevity, which improved the specific productivity and total yield of recombinant IgG1 in batch cultures by almost 50% for an extra 2 or 3 days of culture. A lower L-glutamine consumption rate was observed in cells cultured in EGCG-containing media, which may be suggesting that there was less stress in the culture environment. Additionally, EGCG did not affect the N-glycan quality of IgG1. Our results indicated that adding EGCG only on the first day of the culture enhanced the specific productivity and total amount of recombinant protein production in batch cultures. This approach may prove to be useful for biopharmaceutical production.

Antioxidant nitroxides protect hepatic cells from oxidative stress-induced cell death

Oxidative stress causes cell death and induces many kinds of disease, including liver disease. Nitroxides are known to react catalytically with free radicals. In this study, the cell protective activities of nitroxides were compared with those of other antioxidants. Nitroxides showed much greater inhibition of hydrogen peroxide-induced cell death than other antioxidants in a hepatic cell line and in primary hepatocytes. The intracellular oxidative stress level at 24 h after hydrogen peroxide stimulation was significantly decreased by nitroxides, but not by other antioxidants. To clarify the mechanism of cell protection by nitroxides, we investigated whether nitroxides inhibited DNA damage and mitogen-activated protein kinase pathway activation. We found that nitroxides reduced caspase-3 activation and may have ultimately inhibited cell death. In conclusion, nitroxides are very useful for attenuating cell damage due to oxidative stress. Nitroxides are thus a potential therapeutic agent for oxidative stress-related diseases.

Effect of epigallocatechin-3-gallate on proliferation and phenotype maintenance in rabbit articular chondrocytes in vitro

In autologous chondrocyte implantation (ACI) to restore defective cartilage, limited cell numbers and dedifferentiation of chondrocytes are the major difficulties. An alternative is the use of growth factors, but their high cost and potential for tumorigenesis are major obstacles. To ensure successful ACI therapy, it is important to find an effective substitute pro-chondrogenic agent. Epigallocatechin-3-gallate (EGCG), one of the green tea catechins, has been widely investigated in studies of interleukin-1β-induced chondrocytes. In the present study, the effects of EGCG on rabbit articular chondrocytes were investigated through the examination of cell proliferation, morphology, glycosaminoglycan synthesis and cartilage-specific gene expression. The results showed that EGCG could effectively promote chondrocyte growth and enhance the secretion and synthesis of the cartilage extracellular matrix by upregulating expression levels of aggrecan, collagen II and Sox9 genes. Expression of the collagen I gene was downregulated, which showed that EGCG effectively inhibited the dedifferentiation of chondrocytes. Hypertrophy, which may lead to chondrocyte ossification, was also undetectable in the EGCG groups. In conclusion, the recommended dose of EGCG was found to be in the range of 5 to 20 μM, with the most marked response observed with 10 μM. The present study may provide a basis for the development of a novel agent as a substitute for growth factors in the treatment of articular cartilage defects.

Nutritional imbalances linking cellular senescence and type 2 diabetes mellitus

PURPOSE OF REVIEW

Quality of nutrition plays a central role in illnesses such as diabetes and its complications. Dietary and lifestyle habits may have a strong impact, either worsening or improving the evolution of diabetes mellitus. Some factors, such as obesity, worsen the illness, causing chronic inflammation, lipid metabolic disorder, accelerated atherosclerosis, increased risk for thrombosis, hypertension, hyperinsulinemia, insulin resistance, and cellular senescence. Some other nutritional components, however, have an opposite effect, probably increasing antioxidant defense.

RECENT FINDINGS

The effects of nutritional factors on cellular senescence in diabetic patients are described in this review. In particular, we discuss some of the nutritional causes of cellular senescence in diabetes mellitus and focus on different nutraceutical compounds that can affect cellular senescence. Furthermore, relevant mechanisms of action are also described.

SUMMARY

Diet and nutraceutical factors have important effects on diabetes mellitus. Some molecules, which improve antioxidant defense, may counteract cellular senescence. A good lifestyle with physical activity and good weight control can improve the quality of life in diabetic people; on the contrary, obesity and vitamin deficiencies may worsen the evolution of this illness, even inducing cellular senescence.

Anti-inflammatory effect of (-)-epigallocatechin-3-gallate on Porphyromonas gingivalis lipopolysaccharide-stimulated fibroblasts and stem cells derived from human periodontal ligament

PURPOSE

(-)-epigallocatechin-3-gallate (EGCG) has been reported to exert anti-inflammatory and antibacterial effects in periodontitis. However, its exact mechanism of action has yet to be determined. The present in vitro study evaluated the anti-inflammatory effects of EGCG on human periodontal ligament fibroblasts (hPDLFs) and human periodontal ligament stem cells (hPDLSCs) affected by bacterial lipopolysaccharide (LPS) extracted from Porphyromonas gingivalis.

METHODS

hPDLFs and hPDLSCs were extracted from healthy young adults and were treated with EGCG and/or P. gingivalis LPS. After 1, 3, 5, and 7 days from treatment, cytotoxic and proliferative effects were evaluated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and bromodeoxyuridine assay, respectively. And then, the gene expressions of hPDLFs and hPDLSCs were observed for interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, osteoprotegerin (OPG), receptor activator of nuclear factor kappa-B ligand (RANKL), and RANKL/OPG using real-time polymerase chain reaction (PCR) at 0, 6, 24, and 48 hours after treatment. The experiments were performed with the following groups for hPDLFs and hPDLSCs; 1) No treat, 2) EGCG alone, 3) P. gingivalis LPS alone, 4) EGCG+P. gingivalis LPS.

RESULTS

The 20 µM of EGCG and 20 µg/mL of P. gingivalis LPS had the lowest cytotoxic effects, so those concentrations were used for further experiments. The proliferations of hPDLFs and hPDLSCs increased in all groups, though the 'EGCG alone' showed less increase. In real-time PCR, the hPDLFs and hPDLSCs of 'EGCG alone' showed similar gene expressions to those cells of 'no treat'. The gene expressions of 'P. gingivalis LPS alone' in both hPDLFs and hPDLSCs were highly increased at 6 hours for IL-1β, IL-6, TNF-α, RANKL, and RANKL/OPG, except the RANKL/OPG in hPDLSCs. However, those increased gene expressions were down-regulated in 'EGCG+P. gingivalis LPS' by the additional treatment of EGCG.

CONCLUSIONS

Our results demonstrate that EGCG could exert an anti-inflammatory effect in hPDLFs and hPDLSCs against a major pathogen of periodontitis, P. gingivalis LPS.

Preventive effects of epigallocatechin-3-O-gallate against replicative senescence associated with p53 acetylation in human dermal fibroblasts

Considering the various pharmacological activities of epigallocatechin-3-O-gallate (EGCG) including anticancer, and anti-inflammatory, antidiabetic, and so forth, relatively less attention has been paid to the antiaging effect of EGCG on primary cells. In this study, the preventive effects of EGCG against serial passage-induced senescence were investigated in primary cells including rat vascular smooth muscle cells (RVSMCs), human dermal fibroblasts (HDFs), and human articular chondrocytes (HACs). The involvement of Sirt1 and acetylated p53 was examined as an underlying mechanism for the senescence preventive activity of EGCG in HDFs. All cells were employed with the initial passage number (PN) between 3 and 7. For inducing senescence, the cells were serially passaged at the predetermined times and intervals in the absence or presence of EGCG (50 or 100 μM). Serial passage-induced senescence in RVSMCs and HACs was able to be significantly prevented at 50 μM EGCG, while in HDFs, 100 μM EGCG could significantly prevent senescence and recover their cell cycle progression close to the normal level. Furthermore, EGCG was found to prevent serial passage- and H(2)O(2)-induced senescence in HDFs by suppressing p53 acetylation, but the Sirt1 activity was unaffected. In addition, proliferating HDFs showed similar cellular uptake of FITC-conjugated EGCG into the cytoplasm with their senescent counterparts but different nuclear translocation of it from them, which would partly account for the differential responses to EGCG in proliferating versus senescent cells. Taking these results into consideration, it is suggested that EGCG may be exploited to craft strategies for the development of an antiaging or age-delaying agent.

Attenuation of Murine Graft-Versus-Host Disease by a Tea Polyphenol

Since donor T-cells' allorecognition of host antigens is a prerequisite for the onset of graft-versus-host disease (GVHD), blocking their cellular signaling pathways can decrease the severity of GVHD. We hypothesized that epigallocatechin-3-gallate (EGCG), due to its strong affinity to macromolecules, would adhere to surface molecules of donor T cells, inhibit their allorecognition, and attenuate GVHD in the recipient. We tested the hypothesis by treating donor splenocytes with EGCG in both in vitro and in vivo murine GVHD models. EGCG treatment decreased the proliferation of donor cells in MLR cultures and secretion of IL-2 and INF-γ. It also reduced the epitope detection of CD3∊, CD4, and CD28 but did not downregulate the protein expression of these molecules, suggesting blockage of cell surface stimulatory signals. Similarly, EGCG treatment did not decrease mRNA expression for some of these molecules but decreased mitogen-induced cell proliferation, indicating that EGCG did not interfere the transcription of these genes but affected cell proliferation pathways. Furthermore, EGCG-treated donor splenocytes, when transplanted into immunocompromized recipient mice, decreased of proliferation, and the treatment extended the recipients' survival at least during the early stage of GVHD. These results strongly suggest that EGCG attenuates GVHD by both blocking specific cell surface molecules and affecting the donor T-cell proliferation pathways.

(-)-Epigallocatechin-3-gallate blocks 3T3-L1 adipose conversion by inhibition of cell proliferation and suppression of adipose phenotype expression

AIMS

A major objective in the treatment of obese individuals is the development of agents that reduce body fat and improve metabolic homeostasis. Among a variety of biological effects, green tea exerts an anti-obesity effect; however, the mechanisms behind its activity on adipose tissue are uncertain. Tea contains high levels of (-)-epigallocatechin-3-gallate (EGCG), which is one of its main bioactive substances. Therefore, we studied the effects of EGCG on mouse embryonic fibroblast-adipose like cell line (3T3-L1) preadipocyte proliferation and differentiation.

MAIN METHODS

3T3-L1 cells were incubated with physiologically attainable (0.1-1 μM) and pharmacological (5μM, 10μM) concentrations of EGCG for various lengths of time. Cell proliferation was assessed by cell counting and cell cycle analysis. Adipose conversion was evaluated by lipid accumulation and expression of CCAAT/enhancer binding protein alpha (C/EBPα) and peroxisome proliferator-activated receptor gamma (PPARγ) transcription factors.

KEY FINDINGS

A dose dependent suppressive effect on preadipocyte proliferation was observed, with the highest reduction in cell number at 10μM EGCG. On the other hand, adipose conversion was fully inhibited with 10μM EGCG. Flow-cytometric analysis showed that 3T3-L1 cells treated with EGCG underwent an arrest of cell cycle at G2/M. The inhibition of the expression of C/EBPα and PPARγ was accompanied by the inhibitory effect of EGCG. Microscopic observation showed that 3T3-L1 cells treated with EGCG maintained the fibroblastic shape and failed to accumulate cytoplasmic fat droplets even after the induction of differentiation.

SIGNIFICANCE

Our results suggest that EGCG reduces adipogenesis through an arrest of cell cycle and a blockage of adipose phenotype expression. These results also suggest that the anti-obesity activity of green tea may be partially attributed to its suppressive effects in adipogenesis.

Apoptosis of human fibrosarcoma HT-1080 cells by epigallocatechin-3-O-gallate via induction of p53 and caspases as well as suppression of Bcl-2 and phosphorylated nuclear factor-κB

Animal tumor bioassays and in vitro cell culture systems have demonstrated that epigallocatechin-3-O-gallate (EGCG), the predominant catechin in green tea, possesses anti-proliferative and pro-apoptotic effects on various cancer cells and tumors. In this study, we investigated the effects of EGCG on cell growth, cell cycle progression, and apoptosis in human fibrosarcoma HT-1080 cells. The involvement of p53, Bcl-2, Bax, caspases, and nuclear factor-κB (NF-κB) was examined as a mechanism for the anti-cancer activity of EGCG. Time-dependent intracellular trafficking of EGCG was also determined using fluorescein isothiocyanate (FITC)-conjugated EGCG (FITC-EGCG). Our data show that EGCG treatment caused dose-dependent cell growth inhibition, cell cycle arrest at the G(0)/G(1) phase, and DNA fragmentation suggesting the induction of apoptosis in HT-1080 cells. Immunoblot analysis revealed that the expression of p53, caspase-7 and -9 as well as the ratio of Bax/Bcl-2 protein increased significantly with higher EGCG concentrations and longer incubation times. Moreover, expression of phosphorylated NF-κB/p65 in HT-1080 cells was inhibited by EGCG treatment in a dose-dependent manner, while that of unphosphorylated NF-κB/p65 remained unaffected. Here we also reveal time-dependent internalization of FITC-EGCG into the cytosol of HT-1080 cells and its subsequent nuclear translocation. These results suggest that EGCG may interrupt exogenous signals directed towards genes involved in proliferation and cell cycle progression. Taken together, our data indicate that HT-1080 apoptosis may be mediated through the induction of p53 and caspases by the pro-oxidant activity of internalized EGCG, as well as suppression of Bcl-2 and phosphorylated NF-κB by the antioxidant activity of EGCG.

Epigallocatechin-3-gallate regulates cell growth, cell cycle and phosphorylated nuclear factor-κB in human dermal fibroblasts

AIM

To investigate the effects of (-)epigallocatechin-3-gallate (EGCG), the main polyphenol in green tea, on cell growth, cell cycle and phosphorylated nuclear factor-κB (pNF-κB) expression in neonatal human dermal fibroblasts (nHDFs).

METHODS

The proliferation and cell-cycle of nHDFs were determined using WST-8 cell growth assay and flow cytometry, respectively. The apoptosis was examined using DNA ladder and Annexin V-FITC assays. The expression levels of pNF-κB and cell cycle-related genes and proteins in nHDFs were measured using cDNA microarray analyses and Western blot. The cellular uptake of EGCG was examined using fluorescence (FITC)-labeled EGCG (FITC-EGCG) in combination with confocal microscopy.

RESULTS

The effect of EGCG on the growth of nHDFs depended on the concentration tested. At a low concentration (200 μmol/L), EGCG resulted in a slight decrease in the proportion of cells in the S and G(2)/M phases of cell cycle with a concomitant increase in the proportion of cells in G(0)/G(1) phase. At the higher doses (400 and 800 μmol/L), apoptosis was induced. The regulation of EGCG on the expression of pNF-κB was also concentration-dependent, whereas it did not affect the unphosphorylated NF-κB expression. cDNA microarray analysis showed that cell cycle-related genes were down-regulated by EGCG (200 μmol/L). The expression of cyclins A/B and cyclin-dependent kinase 1 was reversibly regulated by EGCG (200 μmol/L). FITC-EGCG was found to be internalized into the cytoplasm and translocated into the nucleus of nHDFs.

CONCLUSION

EGCG, through uptake into cytoplasm, reversibly regulated the cell growth and expression of cell cycle-related proteins and genes in normal fibroblasts.

Effect of (-)-epigallocatechin-3-gallate on maintaining the periodontal ligament cell viability of avulsed teeth: a preliminary study

PURPOSE

Avulsed tooth can be completely recovered, if sound periodontal ligament (PDL) of tooth is maintained. Although a lot of storage solutions have been explored for the better storage of avulsed tooth, there is a shortcoming that the preservation time is much short. On the other hand, there has been studies that (-)-epigallocatechin-3-gallate (EGCG), the most abundant polyphenol in green tea, which is related to the anti inflammatory, antioxygenic, and antibacterial effects, allows the successful preservations of tissues and cells. This study evaluated the effect of EGCG on avulsed-teeth preservation of Beagle dogs for a period of time.

METHODS

The atraumatically extracted teeth of Beagle dogs were washed and preserved with 0/10/100 µM of EGCG at the time of immediate, period 1 (4 days in EGCG-contained media and additional 1 day in EGCG-free media), period 2 (8 days in EGCG-contained media and additional 2 days in EGCG-free media) and period 3 (12 days in EGCG-contained media and additional 2 days in EGCG-free media). Then, the cell viabilities of preserved teeth was calculated by dividing optical density (OD) of 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay with OD of eosin assay to eliminate the measurement errors caused by the different tissue volumes.

RESULTS

From the results, the immediately analyzed group presented the highest cell viability, and the rate of living cells on teeth surface decreased dependent on the preservation period. However, the 100 µM of EGCG-treated group showed statistically significant positive cell activity than EGCG-free groups throughout preservation periods.

CONCLUSIONS

Our findings showed that 100 µM EGCG could maintain PDL cell viability of extracted tooth. These results suggest that although EGCG could not be a perfect additive for tooth preservation, it is able to postpone the period of tooth storage. However, further in-depth studies are required for more plausible use of EGCG.

Biological and Biomechanical Evaluations of Osteochondral Allografts Preserved in Cold Storage Solution Containing Epigallocatechin Gallate

The beneficial effects of (-)-epigallocatechin-3- O-gallate (EGCG) on the nonfrozen preservation of mammalian cells and tissues are generally not well understood. A storage solution containing EGCG was employed to test the hypothesis that EGCG is capable of extending the storage duration for the cold preservation of articular cartilages. Human articular cartilages were preserved in a storage solution composed of serum-free RPMI-1640 medium with 1% antibiotic-antimycotic solution and 1 mM EGCG at 4°C for 1, 2, and 4 weeks. The chondrocyte viability (CCK-8 assay), biochemical and immunohistochemical composition [glycosaminoglycans (GAG) and (type II) collagen], and biomechanical property (compressive elastic modulus) were assessed. The chondrocyte viability of the cartilages preserved with EGCG was significantly well maintained for at least 2 weeks with high content of GAG and total collagen. These beneficial effects of EGCG were confirmed by the immunohistochemical observations of well-preserved cartilaginous structures and delayed denaturation of the extracellular matrix in preserved cartilages. There was no significant difference in the compressive elastic modulus (MPa) between the cartilages preserved with and without EGCG. These results suggest that EGCG may play an effective role in preserving osteochondral allografts, which can be exploited in devising strategies for the long-term preservation of other tissues under cold storage conditions.

Functional genomics of endothelial cells treated with anti-angiogenic or angiopreventive drugs

Angiogenesis is a highly regulated physiological process that has been studied in considerable detail given its importance in several chronic pathologies. Many endogenous factors and hormones intervene in the regulation of angiogensis and classical as well as targeted drugs have been developed for its control. Angiogenesis inhibition has come off the bench and entered into clinical application for cancer therapy, particularly for metastatic disease. While the clinical benefit is currently in terms of months, preclinical data suggest that novel drugs and drug combinations could lead to substantial improvement. The many targets of endogenous angiogenesis inhibitors reflect the complexity of the process; in contrast, current clinical therapies mainly target the vascular endothelial growth factor system. Cancer chemopreventive compounds can retard tumor insurgence and delay or prevent metastasis and many of these molecules hinder angiogenesis, a mechanism that we termed angioprevention. Angiopreventive drugs appear to prevalently act through the inhibition of the pro-inflammatory and anti-apoptotic player NFkappaB, thus contrasting inflammation dependent angiogenesis. Relatively little is known concerning the effects of these angiogenesis inhibitors on gene expression of endothelial cells, the main target of many of these molecules. Here we provide an exhaustive list of anti-angiogenic molecules, and summarize their effects, where known, on the transcriptome and functional genomics of endothelial cells. The regulation of specific genes can be crucial to preventive or therapeutic intervention. Further, novel targets might help to circumvent resistance to anti-angiogenic therapy. The studies we review are relevant not only to cancer but also to other chronic degenerative diseases involving endothelial cells, such as cardiovascular disorders, diabetes, rheumatoid arthritis and retinopaties, as well as vessel aging.