Limits...
Epigallocatechin-3-gallate suppresses the expression of HSP70 and HSP90 and exhibits anti-tumor activity in vitro and in vivo.

Tran PL, Kim SA, Choi HS, Yoon JH, Ahn SG - BMC Cancer (2010)

Bottom Line: The aim of this study was to examine the effect of EGCG on the expression of heat shock proteins (HSPs) and tumor suppression.Treatment with EGCG decreased cell proliferation and colony formation of MCF-7 human breast cancer cells.Moreover, treatment with EGCG (10 mg/kg) in a xenograft model resulted in delayed tumor incidence and reduced tumor size, as well as the inhibition of HSP70 and HSP90 expression.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pathology, Chosun University, College of Dentistry, Gwangju 501-759, Republic of Korea.

ABSTRACT

Background: Epigallocatechin-3-gallate (EGCG), one of the major catechins in green tea, is a potential chemopreventive agent for various cancers. The aim of this study was to examine the effect of EGCG on the expression of heat shock proteins (HSPs) and tumor suppression.

Methods: Cell colony formation was evaluated by a soft agar assay. Transcriptional activity of HSP70 and HSP90 was determined by luciferase reporter assay. An EGCG-HSPs complex was prepared using EGCG attached to the cyanogen bromide (CNBr)-activated Sepharose 4B. In vivo effect of EGCG on tumor growth was examined in a xenograft model.

Results: Treatment with EGCG decreased cell proliferation and colony formation of MCF-7 human breast cancer cells. EGCG specifically inhibited the expression of HSP70 and HSP90 by inhibiting the promoter activity of HSP70 and HSP90. Pretreatment with EGCG increased the stress sensitivity of MCF-7 cells upon heat shock (44 degrees C for 1 h) or oxidative stress (H2O2, 500 microM for 24 h). Moreover, treatment with EGCG (10 mg/kg) in a xenograft model resulted in delayed tumor incidence and reduced tumor size, as well as the inhibition of HSP70 and HSP90 expression.

Conclusions: Overall, these findings demonstrate that HSP70 and HSP90 are potent molecular targets of EGCG and suggest EGCG as a drug candidate for the treatment of human cancer.

Show MeSH

Related in: MedlinePlus

FEGCG suppresses the expression of HSP70 and HSP90 in MCF-7 cells. (A) The cells were treated with EGCG for 24 h and the expression levels of heat shock proteins were determined by Western blot analysis. (B) The levels of HSP90, HSP70, and HSP60 mRNA were detected by RT-PCR analysis. GAPDH was used as an internal control. (C) The cells were harvested 24 h after EGCG treatment. Cell lysates were subjected to Western blot analysis for Akt and Bcl-2. (D), (E) MCF-7 cells were transfected with pGL3-HSP70 (D) or pXP2-HSP90 (E) reporter vector. After 24 h, cells were heat shocked at 42°C for 1 h followed by recovery at 37°C for 24 h with EGCG (100 μM). Cells were harvested and the cell extracts were subjected to luciferase assay. The results were represented as the mean ± SD of three independent experiments. Asterisk, P < 0.05, significantly different from control. (F) The cells were treated with indicated concentrations of EGCG for 24 h. The expression levels of HSF1 and HSF2 were monitored by Western blot analysis.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2927993&req=5

Figure 3: FEGCG suppresses the expression of HSP70 and HSP90 in MCF-7 cells. (A) The cells were treated with EGCG for 24 h and the expression levels of heat shock proteins were determined by Western blot analysis. (B) The levels of HSP90, HSP70, and HSP60 mRNA were detected by RT-PCR analysis. GAPDH was used as an internal control. (C) The cells were harvested 24 h after EGCG treatment. Cell lysates were subjected to Western blot analysis for Akt and Bcl-2. (D), (E) MCF-7 cells were transfected with pGL3-HSP70 (D) or pXP2-HSP90 (E) reporter vector. After 24 h, cells were heat shocked at 42°C for 1 h followed by recovery at 37°C for 24 h with EGCG (100 μM). Cells were harvested and the cell extracts were subjected to luciferase assay. The results were represented as the mean ± SD of three independent experiments. Asterisk, P < 0.05, significantly different from control. (F) The cells were treated with indicated concentrations of EGCG for 24 h. The expression levels of HSF1 and HSF2 were monitored by Western blot analysis.

Mentions: Several reports have revealed that HSPs are important mediators of chemotherapy resistance. Therefore, we investigated the effect of EGCG on the expression of various HSPs. MCF-7 cells were incubated with increasing concentrations of EGCG (10 ~ 200 μM) for 24 h. As shown in Figure 3A and 3B, the levels of protein and mRNA of HSP70 and HSP90 were decreased by 100 μM of EGCG, while the other HSPs (HSP110, HSP60, HSP40, and HSP27) were unaffected. In addition, EGCG inhibited the expression of HSP90-regulated Akt and Bcl-2 in MCF-7 cells (Figure 3C).


Epigallocatechin-3-gallate suppresses the expression of HSP70 and HSP90 and exhibits anti-tumor activity in vitro and in vivo.

Tran PL, Kim SA, Choi HS, Yoon JH, Ahn SG - BMC Cancer (2010)

FEGCG suppresses the expression of HSP70 and HSP90 in MCF-7 cells. (A) The cells were treated with EGCG for 24 h and the expression levels of heat shock proteins were determined by Western blot analysis. (B) The levels of HSP90, HSP70, and HSP60 mRNA were detected by RT-PCR analysis. GAPDH was used as an internal control. (C) The cells were harvested 24 h after EGCG treatment. Cell lysates were subjected to Western blot analysis for Akt and Bcl-2. (D), (E) MCF-7 cells were transfected with pGL3-HSP70 (D) or pXP2-HSP90 (E) reporter vector. After 24 h, cells were heat shocked at 42°C for 1 h followed by recovery at 37°C for 24 h with EGCG (100 μM). Cells were harvested and the cell extracts were subjected to luciferase assay. The results were represented as the mean ± SD of three independent experiments. Asterisk, P < 0.05, significantly different from control. (F) The cells were treated with indicated concentrations of EGCG for 24 h. The expression levels of HSF1 and HSF2 were monitored by Western blot analysis.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2927993&req=5

Figure 3: FEGCG suppresses the expression of HSP70 and HSP90 in MCF-7 cells. (A) The cells were treated with EGCG for 24 h and the expression levels of heat shock proteins were determined by Western blot analysis. (B) The levels of HSP90, HSP70, and HSP60 mRNA were detected by RT-PCR analysis. GAPDH was used as an internal control. (C) The cells were harvested 24 h after EGCG treatment. Cell lysates were subjected to Western blot analysis for Akt and Bcl-2. (D), (E) MCF-7 cells were transfected with pGL3-HSP70 (D) or pXP2-HSP90 (E) reporter vector. After 24 h, cells were heat shocked at 42°C for 1 h followed by recovery at 37°C for 24 h with EGCG (100 μM). Cells were harvested and the cell extracts were subjected to luciferase assay. The results were represented as the mean ± SD of three independent experiments. Asterisk, P < 0.05, significantly different from control. (F) The cells were treated with indicated concentrations of EGCG for 24 h. The expression levels of HSF1 and HSF2 were monitored by Western blot analysis.
Mentions: Several reports have revealed that HSPs are important mediators of chemotherapy resistance. Therefore, we investigated the effect of EGCG on the expression of various HSPs. MCF-7 cells were incubated with increasing concentrations of EGCG (10 ~ 200 μM) for 24 h. As shown in Figure 3A and 3B, the levels of protein and mRNA of HSP70 and HSP90 were decreased by 100 μM of EGCG, while the other HSPs (HSP110, HSP60, HSP40, and HSP27) were unaffected. In addition, EGCG inhibited the expression of HSP90-regulated Akt and Bcl-2 in MCF-7 cells (Figure 3C).

Bottom Line: The aim of this study was to examine the effect of EGCG on the expression of heat shock proteins (HSPs) and tumor suppression.Treatment with EGCG decreased cell proliferation and colony formation of MCF-7 human breast cancer cells.Moreover, treatment with EGCG (10 mg/kg) in a xenograft model resulted in delayed tumor incidence and reduced tumor size, as well as the inhibition of HSP70 and HSP90 expression.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pathology, Chosun University, College of Dentistry, Gwangju 501-759, Republic of Korea.

ABSTRACT

Background: Epigallocatechin-3-gallate (EGCG), one of the major catechins in green tea, is a potential chemopreventive agent for various cancers. The aim of this study was to examine the effect of EGCG on the expression of heat shock proteins (HSPs) and tumor suppression.

Methods: Cell colony formation was evaluated by a soft agar assay. Transcriptional activity of HSP70 and HSP90 was determined by luciferase reporter assay. An EGCG-HSPs complex was prepared using EGCG attached to the cyanogen bromide (CNBr)-activated Sepharose 4B. In vivo effect of EGCG on tumor growth was examined in a xenograft model.

Results: Treatment with EGCG decreased cell proliferation and colony formation of MCF-7 human breast cancer cells. EGCG specifically inhibited the expression of HSP70 and HSP90 by inhibiting the promoter activity of HSP70 and HSP90. Pretreatment with EGCG increased the stress sensitivity of MCF-7 cells upon heat shock (44 degrees C for 1 h) or oxidative stress (H2O2, 500 microM for 24 h). Moreover, treatment with EGCG (10 mg/kg) in a xenograft model resulted in delayed tumor incidence and reduced tumor size, as well as the inhibition of HSP70 and HSP90 expression.

Conclusions: Overall, these findings demonstrate that HSP70 and HSP90 are potent molecular targets of EGCG and suggest EGCG as a drug candidate for the treatment of human cancer.

Show MeSH
Related in: MedlinePlus