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Advances in Brief |
Saitama Cancer Center Research Institute, Saitama 362-0806, Japan
| ABSTRACT |
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release from BALB/c-3T3 cells by EGCG and other tea polyphenols with a galloyl moiety in a dose-dependent manner. Moreover, the effects of EGCG on induction of apoptosis were also synergistically enhanced by other cancer-preventive agents, such as sulindac and tamoxifen. This paper reports significant evidence that whole green tea is a more reasonable mixture of tea polyphenols for cancer prevention in humans than EGCG alone and that it is even more effective when it is used in combination with other cancer preventives. | Introduction |
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Green tea contains several tea polyphenols, including EGCG, EGC, ECG, and EC. Their composition varies depending on the location of cultivation of the tea plant (Camellia sinensis), variety of the plant, season of harvest, and manufacturing process. The usual composition is 1015% EGCG, 610% EGC, 23% ECG, and 2% EC, with EGCG being the main constituent by our analysis. As we reported previously (4) , tea polyphenols inhibit growth of human lung cancer cell line PC-9, with the order of potency being EGCG = ECG > EGC >> EC (4) . From these results, EGCG would appear to be the most important compound of the four because of its activity and its high content, but we found that green tea extract, i.e., tea itself, had stronger effects than the polyphenol content would have indicated (3) . This allows us to think that the constituents of green tea extract together have synergistic or additive effects on cancer-preventive activity. Support for this idea was obtained from our discovery that [3H]EGCG incorporation was significantly enhanced by EC, suggesting that EGCG has synergistic potential for cancer-preventive activity with EC. Moreover, synergistic possibilities of other tea polyphenols with EC or those of EGCG with other cancer-preventive agents could be anticipated. To test our hypothesis, we chose induction of apoptosis as a parameter of synergistic effects because apoptosis is commonly induced by tea polyphenols, sulindac, and tamoxifen (5 , 9 , 11) .
Here, we present the first evidence that cotreatment with EGCG and EC, ECG and EC, and EGC and EC synergistically induced apoptosis of PC-9 cells, mediated through enhanced incorporation of tea polyphenols into the cells. Furthermore, cotreatment with EGCG and sulindac or EGCG and tamoxifen significantly enhanced induction of apoptosis by EGCG. These results strongly indicate that green tea itself is a more effective and practical cancer preventive than EGCG alone and that drinking green tea enhances the cancer-preventive activity of sulindac and tamoxifen, resulting in smaller doses of these drugs and fewer adverse effects.
| Materials and Methods |
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[3H]EGCG Incorporation into PC-9 Cells.
PC-9 cells were cultured in RPMI 1640 (Nissui Pharmaceutical Co., Tokyo, Japan) containing phenol red, kanamycin, and 10% fetal bovine serum. PC-9 cells (1 x 106) were incubated with 100 µM [3H]EGCG (4 x 107 dpm) with or without various concentrations of each tea polyphenol for 1 h at 37°C. After incubation, cell-associated radioactivity was measured by scintillation counter, as described previously (4)
. 3H radioactivity incorporated into PC-9 cells without tea polyphenols was taken to be 100%. Results are expressed as the means of two independent experiments performed in duplicate.
DNA Fragmentation.
PC-9 cells (2 x 105 cells/ml) in 24-well plates were incubated with each compound at various concentrations in the absence or presence of EC for 2 days. DNA fragmentation was measured by quantitation of cytosolic oligonucleosome-bound DNA by using an ELISA kit (Boehringer Mannheim, Mannheim, Germany), according to the manufacturers instructions. Briefly, the cytosolic fraction corresponding to
2 x 104105 cells/ml was used as the source in a sandwich ELISA with a primary antihistone antibody coated on the microtiter plate and a secondary anti-DNA antibody coupled to peroxidase. Amounts of oligonucleosome released into cytoplasm were detected by their absorbance at 415 nm. The results were confirmed by two independent experiments performed in duplicate.
Growth Inhibition of PC-9 Cells.
PC-9 cells (4 x 105 cells/ml) were incubated with EGCG, ECG, or EGC in the absence or presence of EC for 2 days. Numbers of viable cells were counted by the trypan blue dye exclusion test (4)
. Percentage of control was calculated as follows: [number of viable cells in a treated group/number of viable cells in a nontreated group (
14 x 105 cells/ml)] x 100%. The results were confirmed by two independent experiments performed in duplicate.
Inhibition of TNF-
Release from BALB/c-3T3 Cells.
BALB/c-3T3 cells were maintained in MEM (Nissui Pharmaceutical Co.) containing 10% fetal bovine serum. BALB/c-3T3 cells (2 x 105 cells per 0.5 ml) in a 12-well plate were preincubated with each of the tea polyphenols for 1 h. Then, 0.2 µM okadaic acid was added to the medium. Twenty-four h after incubation, concentration of TNF-
in the medium was determined by ELISA (Genzyme, Cambridge, MA), as described previously (12)
. The results were confirmed by two independent experiments performed in duplicate.
Statistical Analysis.
The Students t test was performed to compare [3H]EGCG incorporation and induction of apoptosis. Statistical significance levels were P
0.05 and P
0.01.
| Results and Discussion |
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120,000 dpm per 106 PC-9 cells 1 h after incubation with 100 µM [3H]EGCG (4 x 107 dpm). Incubation of [3H]EGCG with nonradioactive EGCG decreased the incorporated radioactivity in a dose-dependent manner (Fig. 1)
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2.1-fold. Moreover, EC at a concentration of 200 µM stimulated induction of apoptosis by ECG and EGC
2-fold and
3-fold, respectively (Table 1)
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2.7-fold. These results correlated well with the results of enhanced [3H]EGCG incorporation and enhanced apoptosis (Fig. 2
Synergistic Effects of EC with EGCG and ECG on Inhibition of TNF-
Release.
On the basis of our finding that TNF-
is an endogenous tumor promoter, we think increase of TNF-
in organs, including lung, may promote carcinogenesis (13)
. We also found that various cancer inhibitors including EGCG commonly inhibited TNF-
gene expression and its release from BALB/c-3T3 cells. Therefore, we think reduction of TNF-
level is a key criterion of cancer-preventive agents (14)
. Therefore, we next examined whether EC enhances inhibition of TNF-
release. Table 1
shows that EC alone did not inhibit TNF-
release significantly up to concentrations of 500 µM, whereas EGCG inhibited it with an IC50 of 60 µM. Treatment with EGCG and 100 µM EC reduced the IC50 from 60 to 15 µM (i.e., 4-fold enhancement). Similarly, EC also stimulated the inhibitory effects of ECG on TNF-
release, reducing IC50 from 30 to 7 µM. These results clearly demonstrated that EC stimulates the cancer-preventive activity of EGCG and other tea polyphenols mediated through inhibition of TNF-
release and induction of apoptosis (Table 1)
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| Enhancing Effects of EGCG with Sulindac or Tamoxifen. |
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release from BALB/c-3T3 cells (10
, 11
, 14)
. As we expected, both sulindac and tamoxifen significantly and synergistically enhanced apoptosis induced in PC-9 cells by EGCG. Specifically, Fig. 3
release from BALB/c-3T3 cells, as well as in inhibition of cell growth of human breast cancer cell line, MCF-7 (data not shown). A combination of green tea extract and tamoxifen synergistically reduced development of spontaneous mammary tumors in C3H/Ouj mice (17)
and of carcinogen-induced mammary tumors in rodents.5
A recent epidemiological study revealed that increased consumption of green tea resulted in decreased recurrence of breast cancer in Japanese patients (18)
. Thus, there is a significant possibility that high consumption of green tea (usually > 10 cups per day) will enhance the preventive activity of tamoxifen against breast cancer development.
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| ACKNOWLEDGMENTS |
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| FOOTNOTES |
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1 This work was supported by the following Grants-in-Aid: for Scientific Research on Priority Areas for Cancer Research from the Ministry of Education, Science, Sports and Culture (Japan); for a 2nd-Term Comprehensive 10-Year Strategy for Cancer Control and for Comprehensive Research on Aging and Health from Ministry of Health and Welfare (Japan); and for Selectively Applied and Developed Research from Saitama Prefecture (Japan). This work was also supported by grants from the Uehara Memorial Life Science Foundation, the Smoking Research Fund, and the Plant Science Research Foundation of the Faculty of Agriculture (Kyoto University). ![]()
2 Present address: The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030. ![]()
3 To whom requests for reprints should be addressed, at Saitama Cancer Center Research Institute, Ina, Kitaadachi-gun, Saitama 362-0806, Japan. Phone: 81-48-722-1111; Fax: 81-48-722-1739; E-mail: hfuji{at}saitama-cc.go.jp ![]()
4 The abbreviations used are: EGCG, (-)-epigallocatechin gallate; EGC, (-)-epigallocatechin; ECG, (-)-epicatechin gallate; EC, (-)-epicatechin; TNF-
, tumor necrosis factor-
. ![]()
5 M. Sporn, personal communication. ![]()
Received 9/ 2/98. Accepted 11/10/98.
| REFERENCES |
|---|
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release and of protein isoprenylation. Cancer Res., 53: 3462-3464, 1993.
release in mouse lung tissue. Jpn. J. Cancer Res., 86: 749-755, 1995.[Medline]
expression. Cancer Res., 56: 3711-3715, 1996.This article has been cited by other articles:
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M. R. Sartippour, R. Pietras, D. C. Marquez-Garban, H.-W. Chen, D. Heber, S. M. Henning, G. Sartippour, L. Zhang, M. Lu, O. Weinberg, et al. The combination of green tea and tamoxifen is effective against breast cancer Carcinogenesis, December 1, 2006; 27(12): 2424 - 2433. [Abstract] [Full Text] [PDF] |
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