Inhibitive Effects Of Sodium Butyrate On The Growth Of Breast Carcinoma Mcf-7 Cells

Background and ObjectivesBreast carcinoma is one of the most common malignancies in women. The morbidity of breast carcinoma will continue to increase in the future, and the mortality is the first in female cancer. Though incidence for breast carcinoma in our country is about 18.7/100,000, which is lower than that (80/100,000) of developed countries, the increasing rate is clearly higher than the average of the world. Advances in conventional cancer treatments (surgery, radiotherapy and chemotherapy) have failed to make a significant impact on the prognosis of the patients with late stage, recurrence, and/or metastasis in the last few decades. Therefore, there is a pressing need to develop novel cancer therapies that may complement or even replace current conventional treatment. Sodium butyrate (NaB) is sodium salt of butyric acid, a short chain fatty acid. Proliferation could be inhibited in many cancer cells treated by sodium butyrate, such as liver cancer, gastric cancer, colon cancer, melanoma, ovarian cancer, brain gliocytoma, also cell differentiation could be induced. But there is no report about MCF-7 in this field. So the inhibition effects of sodium butyrate on the growth of breast carcinoma MCF-7 cells were studied in this paper.Materials and Methods1. MCF-7 cells were bought from Cell Bank, Chinese Academy of Sciences, and were cultured in DMEM culture medium including 10% fetal bovine serum (FBS), and were incubated with 5% CO₂ at 37°C.2. To select MCF-7 cells in exponential phase of growth, then the cells were inoculated in 24 hole board , after 24h synchronization the cell were divided into four groups. The first group was the normal control group that was treated by DMEM nutritive contains 10% fetal bovine serum. The other groups was experimental groups, the cell were treated by different concentrations of sodium butyrate (2.5, 5, 10 mmol/L). Changes of rate of growth were observed by the growth curve of MCF-7 treated by different concentrations sodium butyrate, and doubling time was calculated.3. To select MCF-7 cells in exponential phase of growth, then the cells were inoculated. After 24h synchronization the cell were divided control group and 5 mmol/L sodium butyrate experimental group. Then the morphologic changes of MCF-7 cells were viewed by inverted microscope. The changes of colony-forming efficiency were studied by flat colony-forming assay. The distribution of cell cycle and apoptotic changes were analyzed by flow cytometry; The "DNA ladder" was detected by agarose gel electrophoresis.4. Statistical analysis: All the datas were analyzed by SPSS11.5 stastistical package. The comparision mean of two groups uses t-test, the mean of more than two groups uses ANVOA. The comparision of two positive rate uses the Chi-square. The level of significant difference wasα=0.05.Results1. MCF-7 cells of rate of growth and doubling time was influenced by sodium butyrate: Compared to control group MCF-7 cells, relevant changes of MCF-7 cells treated with sodium butyrate included the suppression of growth rate, the protraction of doubling time (the doubling times of MCF-7 parental cells and MCF-7 cells treated with 2.5 mmol/L, 5 mmol/L, and 10mmol/L of sodium butyrate were 29.9h,62.3 h,164.2 h and 301.0 h1).2. MCF-7 cells of colony-forming was influenced by sodium butyrate: Flat colony-forming assay showed that: the average colony numbers of control group MCF-7 cells and experimental group MCF-7 cells treated with sodium butyrate (5 mmol/L) were 72.00±6.27 and 16.70±4.66, respectively, control group of colony-forming was significantly higher than that in experimental group(P<0.05);3. MCF-7 cells of Cell cycle was influenced by sodium butyrate: Cell cycle analyzed by flow cytometry showed that: the proportions of G₁, S and G₂/M of control group MCF-7 cells were 51.50±1.10%, 38.10±0.27%, 10.40±1.00%; while experimental group MCF-7 cells were 82.00±0.62%, 12.90±0.5%, 5.10±0.23%; G₁ was clearly blocked, S and G₂/M were significantly depleted (P< 0.05);4. MCF-7 cells of morphous was influenced by sodium butyrate: Morphologic changes compared to control group MCF-7 cells , experimental group cells gradually shrinked and got round, round cells whose chromatin condensed could be seen after 24 hour, and gradually flatted; round and floating cells became more and more with the time gone;but control group hasn't different.5. MCF-7 cells of apoptosis was influenced by sodium butyrate: Cell apoptosis analyzed by flow cytometry suggested that apoptosis rate of control group MCF-7 cells was 0.14%, experimental group MCF-7 cells was 19.78%, experimental group cells apoptosis distinctly increased(P< 0.05);6. MCF-7 cells of DNA was influenced by sodium butyrate: Agarose gel electrophoresis showed: compared to control group MCF-7 cells, experimental group cells took on clear "DNA ladder".Conclusions1. Experimental group MCF-7 cells were the slowness of rate of growth, long of doubling time, the diminution of colony-forming rates and the block of G1.So Sodium butyrate could suppress the growth of breast cancer. 2. Experimental group MCF-7 cells were apoptosis morphologic changes, the increasing apoptosis number, and the appearance of the "DNA ladder". Sodium butyrate could induce apoptosis of breast cancer.3. To provided the primary theoretical and experimental evidence for the clinical application of sodium butyrate.