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Catechins induced acute promyelocytic leukemia cell apoptosis and triggered PML-RARα oncoprotein degradation.

Zhang L, Chen QS, Xu PP, Qian Y, Wang AH, Xiao D, Zhao Y, Sheng Y, Wen XQ, Zhao WL - J Hematol Oncol (2014)

Bottom Line: It has recently been reported that the extracts of green tea polyphenol have cancer preventive effects.Catechins-mediated apoptotic effect was also observed in primary APL cells without affecting normal hematopoietic progenitor cells.Catechins might be a potential candidate for APL treatment by activating intrinsic apoptotic pathway and targeting PML-RARα oncoprotein.

View Article: PubMed Central - PubMed

ABSTRACT

Background: It has recently been reported that the extracts of green tea polyphenol have cancer preventive effects. In this study, we investigated the effect of the natural composition from green tea leaves Catechins on acute promyelocytic leukemia (APL).

Methods: In vitro, APL cell lines NB4, retinoic acid-resistant NB4-R1 and NB4-R2 were treated with different concentrations of Catechins. Cell viability and cell apoptosis were analyzed using MTT assay and flow cytometric assay, respectively. Expression of proteins related to apoptosis and PML-RARα oncoprotein were assessed by Western blot. In vivo anti-tumor activity of Catechins was examined in nude mice xenografted with NB4 cells and in situ cell apoptosis was detected by terminal deoxytransferase-catalyzed DNA nick-end labeling assay.

Results: Catechins at micromolar concentration levels significantly inhibited APL cell proliferation and induced cell apoptosis, in association with mitochondria damage, ROS production and caspase activation. The anti-apoptotic Bcl-2 family member Bcl-xL was down regulated, with pro-apoptotic member Bax remaining unchanged. Moreover, Catechins induced the degradation of PML-RARα oncoprotein. Catechins-mediated apoptotic effect was also observed in primary APL cells without affecting normal hematopoietic progenitor cells. In the murine xenograft model, Catechins remarkably inhibited tumor growth and induced in situ leukemic cell apoptosis.

Conclusions: Catechins might be a potential candidate for APL treatment by activating intrinsic apoptotic pathway and targeting PML-RARα oncoprotein.

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Catechins induced caspase activation, Bcl-xL downregulation, and the degradation of PML-RARα fusion protein in NB4 cells. (A) Western blot analysis of caspase-3, −8, −9, and PARP in NB4 cells treated with 100 μM and 200 μM Catechins for 24 h. Caspase-3 was activated with caspase-8 and caspase-9 and PARP cleaved. (B) The expression of Bcl-2, Bcl-xL and Bax protein were determined by Western blot. Bcl-xL expression was reduced in NB4 cells treated with 100 μM and 200 μM Catechins for 24 h. (C) PML-RARα was decreased upon treatment with 100 μM and 200 μM Catechins at 12 h and 24 h. (D and E) PML-RARα was not affected by pan-caspase inhibitor ZVAD-FMK (50 μM), but partially blocked by proteasome inhibitor bortezomib (0.1 μM). Three independent experiments were performed and representative results were shown.
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Fig3: Catechins induced caspase activation, Bcl-xL downregulation, and the degradation of PML-RARα fusion protein in NB4 cells. (A) Western blot analysis of caspase-3, −8, −9, and PARP in NB4 cells treated with 100 μM and 200 μM Catechins for 24 h. Caspase-3 was activated with caspase-8 and caspase-9 and PARP cleaved. (B) The expression of Bcl-2, Bcl-xL and Bax protein were determined by Western blot. Bcl-xL expression was reduced in NB4 cells treated with 100 μM and 200 μM Catechins for 24 h. (C) PML-RARα was decreased upon treatment with 100 μM and 200 μM Catechins at 12 h and 24 h. (D and E) PML-RARα was not affected by pan-caspase inhibitor ZVAD-FMK (50 μM), but partially blocked by proteasome inhibitor bortezomib (0.1 μM). Three independent experiments were performed and representative results were shown.

Mentions: In parallel to Δψm loss, western blot analysis showed that Catechins significantly induced activation of caspase-3, −8 and −9 in NB4 cells. Correspondingly, PARP was cleaved to an 89-kDa fragment by Catechins treatment at 24 hours (Figure 3A). These data suggested that Catechins induced cell apoptosis through an intrinsic mitochondrial pathway and was dependent on caspase activation.Figure 3


Catechins induced acute promyelocytic leukemia cell apoptosis and triggered PML-RARα oncoprotein degradation.

Zhang L, Chen QS, Xu PP, Qian Y, Wang AH, Xiao D, Zhao Y, Sheng Y, Wen XQ, Zhao WL - J Hematol Oncol (2014)

Catechins induced caspase activation, Bcl-xL downregulation, and the degradation of PML-RARα fusion protein in NB4 cells. (A) Western blot analysis of caspase-3, −8, −9, and PARP in NB4 cells treated with 100 μM and 200 μM Catechins for 24 h. Caspase-3 was activated with caspase-8 and caspase-9 and PARP cleaved. (B) The expression of Bcl-2, Bcl-xL and Bax protein were determined by Western blot. Bcl-xL expression was reduced in NB4 cells treated with 100 μM and 200 μM Catechins for 24 h. (C) PML-RARα was decreased upon treatment with 100 μM and 200 μM Catechins at 12 h and 24 h. (D and E) PML-RARα was not affected by pan-caspase inhibitor ZVAD-FMK (50 μM), but partially blocked by proteasome inhibitor bortezomib (0.1 μM). Three independent experiments were performed and representative results were shown.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4197244&req=5

Fig3: Catechins induced caspase activation, Bcl-xL downregulation, and the degradation of PML-RARα fusion protein in NB4 cells. (A) Western blot analysis of caspase-3, −8, −9, and PARP in NB4 cells treated with 100 μM and 200 μM Catechins for 24 h. Caspase-3 was activated with caspase-8 and caspase-9 and PARP cleaved. (B) The expression of Bcl-2, Bcl-xL and Bax protein were determined by Western blot. Bcl-xL expression was reduced in NB4 cells treated with 100 μM and 200 μM Catechins for 24 h. (C) PML-RARα was decreased upon treatment with 100 μM and 200 μM Catechins at 12 h and 24 h. (D and E) PML-RARα was not affected by pan-caspase inhibitor ZVAD-FMK (50 μM), but partially blocked by proteasome inhibitor bortezomib (0.1 μM). Three independent experiments were performed and representative results were shown.
Mentions: In parallel to Δψm loss, western blot analysis showed that Catechins significantly induced activation of caspase-3, −8 and −9 in NB4 cells. Correspondingly, PARP was cleaved to an 89-kDa fragment by Catechins treatment at 24 hours (Figure 3A). These data suggested that Catechins induced cell apoptosis through an intrinsic mitochondrial pathway and was dependent on caspase activation.Figure 3

Bottom Line: It has recently been reported that the extracts of green tea polyphenol have cancer preventive effects.Catechins-mediated apoptotic effect was also observed in primary APL cells without affecting normal hematopoietic progenitor cells.Catechins might be a potential candidate for APL treatment by activating intrinsic apoptotic pathway and targeting PML-RARα oncoprotein.

View Article: PubMed Central - PubMed

ABSTRACT

Background: It has recently been reported that the extracts of green tea polyphenol have cancer preventive effects. In this study, we investigated the effect of the natural composition from green tea leaves Catechins on acute promyelocytic leukemia (APL).

Methods: In vitro, APL cell lines NB4, retinoic acid-resistant NB4-R1 and NB4-R2 were treated with different concentrations of Catechins. Cell viability and cell apoptosis were analyzed using MTT assay and flow cytometric assay, respectively. Expression of proteins related to apoptosis and PML-RARα oncoprotein were assessed by Western blot. In vivo anti-tumor activity of Catechins was examined in nude mice xenografted with NB4 cells and in situ cell apoptosis was detected by terminal deoxytransferase-catalyzed DNA nick-end labeling assay.

Results: Catechins at micromolar concentration levels significantly inhibited APL cell proliferation and induced cell apoptosis, in association with mitochondria damage, ROS production and caspase activation. The anti-apoptotic Bcl-2 family member Bcl-xL was down regulated, with pro-apoptotic member Bax remaining unchanged. Moreover, Catechins induced the degradation of PML-RARα oncoprotein. Catechins-mediated apoptotic effect was also observed in primary APL cells without affecting normal hematopoietic progenitor cells. In the murine xenograft model, Catechins remarkably inhibited tumor growth and induced in situ leukemic cell apoptosis.

Conclusions: Catechins might be a potential candidate for APL treatment by activating intrinsic apoptotic pathway and targeting PML-RARα oncoprotein.

Show MeSH
Related in: MedlinePlus