J Breast Cancer.  2011 Mar;14(1):8-13. 10.4048/jbc.2011.14.1.8.

Silibinin Enhances Ultraviolet B-Induced Apoptosis in MCF-7 Human Breast Cancer Cells

Affiliations
  • 1Department of Biochemistry, Institute for Medical Sciences, Chonbuk National University Medical School, Jeonju, Korea.
  • 2Division of Breast, Thyroid Surgery, Department of Surgery, Chonbuk National University Medical School, Jeonju, Korea. shjung@jbnu.ac.kr

Abstract

PURPOSE
Chemotherapies for breast cancer generally have strong cellular cytotoxicity and severe side effects. Thus, significant emphasis has been placed on combinations of naturally occurring chemopreventive agents. Silibinin is a major bioactive flavonolignan extracted from milk thistle with chemopreventive activity in various organs including the skin, prostate, and breast. However, the mechanism underlying the inhibitory action of silibinin in breast cancer has not been completely elucidated. Therefore, we investigated the effect of silibinin in MCF-7 human breast cancer cells and determined whether silibinin enhances ultraviolet (UV) B-induced apoptosis.
METHODS
The effects of silibinin on MCF-7 cell viability were determined using the MTT assay. The effect of silibinin on PARP cleavage, as the hallmark of apoptotic cell death, and p53 protein expression in MCF-7 cells was analyzed using Western blot. The effect of silibinin on UVB-induced apoptosis in MCF-7 cells was analyzed by flow cytometry.
RESULTS
A dose- and time-dependent reduction in viability was observed in MCF-7 cells treated with silibinin. Silibinin strongly induced apoptotic cell death in MCF-7 cells, and induction of apoptosis was associated with increased p53 expression. Moreover, silibinin enhanced UVB-induced apoptosis in MCF-7 cells.
CONCLUSION
Silibinin induced a loss of cell viability and apoptotic cell death in MCF-7 cells. Furthermore, the combination of silibinin and UVB resulted in an additive effect on apoptosis in MCF-7 cells. These results suggest that silibinin might be an important supplemental agent for treating patients with breast cancer.

Keyword

Apoptosis; MCF-7; Silibinin; p53; Ultraviolet B

MeSH Terms

Apoptosis
Blotting, Western
Breast
Breast Neoplasms
Cell Death
Cell Survival
Humans
MCF-7 Cells
Milk Thistle
Prostate
Silymarin
Skin
Silymarin

Figure

  • Figure 1 Structure of silibinin.

  • Figure 2 Effects of silibinin on MCF-7 cell viability. (A) Cells were cultured in 96-well plates until 90% confluence and 200 µM silibinin was then added for 24, 36, 48, and 72 hr. The MTT assay was used to detect cell viability. The optical density (O.D.) value of the control was regarded as 100%. Data points are the means±SEs of more than three experiments (p<0.005). (B) Cells were cultured in 96-well plates until 90% confluence and various concentrations of silibinin (0-200 µM) were added for 72 hr. The MTT assay was used to detect cell viability. The O.D. value of the control was regarded as 100%. Data points are the means±SEs of more than three experiments (p<0.005).

  • Figure 3 Effect of silibinin on PARP cleavage in MCF-7 cells. MCF-7 cells (5×106 cells) were treated with various concentrations of silibinin (0-200 µM) for 72 hr, and whole cell extracts were used for Western blot analysis of PARP. β-actin was used as the loading control.

  • Figure 4 Effect of silibinin on p53 and PTEN expression in MCF-7 cells. MCF-7 cells (5×106 cells) were treated with various concentrations of silibinin (0-200 µM) for 72 hr. Cells were lysed with lysis buffer and the amounts of p53/PTEN and β-actin as a loading control were measured by Western blot (A). The relative density of the electrophoretic band was obtained with a LAS-1000 analyzer (Fujifilm, Japan) (B). Data are means±SEs of four separate experiments (p<0.005).

  • Figure 5 Effect of silibinin and ultraviolet (UV) B on MCF-7 cell viability. MCF-7 cells were treated with 200 µM silibinin and UVB alone or in combination for 72 hr. The MTT assay was used to detect cell viability. The optical density value of the control was regarded as 100%. Data points are the means±SEs of more than three experiments. *p<0.001 (Student's t-test).

  • Figure 6 Effect of silibinin on ultraviolet (UV) B-induced apoptosis in MCF-7 cells. MCF-7 cells were stimulated with UVB (25 mJ/cm2) and silibinin 200 µM for 16 hr. The cells were stained with FITC-conjugated annexin V and propidium iodide and then analyzed by flow cytometry.


Cited by  1 articles

Silibinin-Induced Apoptosis and Downregulation of MicroRNA-21 and MicroRNA-155 in MCF-7 Human Breast Cancer Cells
Masoud Maleki Zadeh, Nasrin Motamed, Najmeh Ranji, Mohammad Majidi, Fahimeh Falahi
J Breast Cancer. 2016;19(1):45-52.    doi: 10.4048/jbc.2016.19.1.45.


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