Advanced Studies in Biology, Vol. 3, 2011, no. 6, 283-288 Evaluation of Silibinin on the Viability of MCF-7 Human Breast Adenocarcinoma and HUVEC (Human Umbilical Vein Endothelial) cell lines Maliheh Entezari 1*, Mohammad Javad Mokhtari 2 and Mehrdad Hashemi 3 1. Department of Genetics, Tehran Medical Branch Islamic Azad University Tehran, Iran (*corresponding author, e-mail: Entezarimali@yahoo.com) 2. Department of Biology, Zarghan Branch Islamic Azad University, Zarghan, Iran 3. Department of Genetics,Tehran Medical Branch Islamic Azad University, Tehran, Iran Abstract. Breast cancer comprises 10.4% of all cancer incidences among women, making it the most common type of non-skin cancer in women and the fifth most common cause of cancer death. Silibinin, also known as silybin, is the major active constituent of silymarin. Silibinin has also demonstrated anticancer effects against human prostate adenocarcinoma cells, estrogen-dependent and independent human breast carcinoma cells, human ectocervical carcinoma cells, human colon cancer cells, and both small and nonsmall human lung carcinoma cells. In the present study, MCF-7 and HUVEC cells were incubated with different concentrations of silibinin (100μg/ml, 150μg/ml and 200μg/ml) at 24h. Then cell cytotoxicity was assessed by MTT assay and IC50 was determined by Pharm software. The results showed that silibinin has dose-dependent inhibitory effect on the viability of MCF-7 cells and with the least inhibitory effect on the viability of normal cells (HUVEC).
284 M. Entezari et al Keywords: Silibinin; Breast Cancer; MCF-7; HUVEC; Normal Cell INTRODUCTION Nowadays cancer is one of the mortality factors in the world which takes place in result of different causes such as mutagenesis and carcinogen chemicals in the environment. Environmental agents which serve as mutagens are cancer factors. According to the statistics almost more than 75% of cancers have an environmental origin (1, 2). Genetic damages and changes in DNA sequences and genes mutations and other changes in chromosomal structure play an important role in cancer (3). Most of mutagenic and carcinogen agents display their destructive effects through free radicals including reactive oxygen s species (ROS). So that antioxidants are able to reduce ROS. ROS have a role in etiology of diseases such as cancer, cardio cellular, nerves problems and senescence. So daily consumption of antioxidants enhances immunity of the body against free radicals production and serves as anticancer agent (4, 6). Some of the fruits and vegetables are considered as the main anticancer foods, because of their abundant antioxidants such as phenols, vitamin C, vitamin E, beta-carotene and lycopene (7). The polyphenolic phytochemical silibinin, a flavonolignan, is a major constituent of the seeds of milk thistle (Silybum Marianum). Silibinin and silymarin, a standardized milk thistle extract of which silibinin is a major component, are widely consumed as dietary supplements, especially in the USA. Silibinin is the most interesting one among these antioxidants (8, 9). This research has been tried to consider anticancer effects of Silibinin on cancerous and normal cells. Materials and methods Cell culture and silibinin treatment MCF-7 and HUVEC cell lines were obtained from the National Cell Bank of Iran (NCBI). The cells were cultured in DMEM containing 10% FBS, 2 mm glutamine, antibiotics (penicillin G, 60 mg/l; streptomycin, 100 mg/l; amphotericin B, 50 μl/l) under a humid atmosphere (37 C, 5% CO2, 95% air). For silibinin treatment, appropriate amounts of stock solution [1mg/ml in dimethyl sulfoxide (Merck, Darmstadt, Germany)] of silibinin (Sigma, USA) were added into culture medium to achieve the indicated concentrations and then incubated with cells for 24h, whereas dimethyl sulfoxide solution without silibinin was used as blank reagent.
Evaluation of silibinin 285 Determination of cell viability The effect of silibinin on MCF-7 cell viability was determined by 3-(4, 5- dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT; Sigma, USA) assay. Briefly, l0 4 cells/well were treated with various concentrations of silibinin (0, 100, 150 and 200μg/ml). After 24 hour incubation the cells were washed twice with phosphate buffered saline (PBS) and MTT (0.5 mg/ml PBS) was added to each well and incubated at 37 C for 3h. The formazan crystals that formed were dissolved by adding dimethyl sulfoxide (100 μl/well), and the absorbance was read at 570 nm using a microplate scanning spectrophotometer (ELISA reader, Organon Teknika, Netherlands). Toxicity level was calculated by the following formula: Mean absorbance of toxicant Cytotoxici ty% = 1 100 Mean absorbance of negative control Viability % = 100 - Cytotoxicity % To diminish test error level, MTT strain was added to some wells without cells and along with other wells, absorbance level was read and ultimately subtracted from whole the absorbance. IC50 determination The 50% inhibition concentration (IC50) values of silibinin on MCF-7 and HUVEC cells at 24h were determined. IC50 was determined by probit analysis using the Pharm PCS (Pharmacologic Calculation System) statistical package (Springer- Verlag, USA) Statistical analysis Statistical significances of difference throughout this study were calculated using a Students t-test and by one-way variance analysis. Results Silibinin cytotoxicity on MCF-7 and HUVEC cells Different concentrations of silibinin (0, 100, 150 and 200μg/ml) at 24h have cytotoxicity effects on MCF-7 and HUVEC cell lines. Compared to the controls, different doses of silibinin (100μg/ml) 10.625% and 96.843%, (150μg/ml) 7.571% and 91.104%, (200μg/ml) 4.334% and 81.434 - decreased MCF-7 and HUVEC cells number, respectively (P<0.05) (Fig. 1)
286 M. Entezari et al The IC50 silibinin after 24h for MCF-7 and HUVEC cell lines was calculated 15.771µg/ml and 387.4156µg/ml, respectively (P<0.05). There was a significant difference between Silibinin effect on growth depression of MCF-7 and HUVEC cells (P<0.01). Figure1:Results of MTT test on Human breast adenocarcinoma and Human Umbilical Vein Endothelial under various concentrations of Silibinin at 24h. Discussion Since usual methods on cancer treatment (surgery, chemical treatment, radiotherapy) have an effect on natural dividing cells, in addition to tumor cell, and kill or arrest their cell division(10). Interest in naturally occurring products is increasing for the prevention of carcinogenesis. Based on this idea, certain foods such as vegetables, fruits, and grains, as well as other phytotherapeutic agents offer high anticancer efficacy and low toxicity to normal tissue. One such dietary agent is silibinin, which has a wide range of pharmacological effects, such as inhibition of DNA synthesis, cell proliferation, cell cycle progression, and apoptosis in various cancer cell lines, including breast cancer. Moreover, the administration of this compound to various animals has been shown to be nontoxic in many studies (11). In 1999, Bhatia et al. reported that treating of prostate, breast, and cervical carcinoma cells with silibinin results in a highly significant inhibition of cell growth and DNA synthesis in a time-dependent manner with a large loss of cell viability only in the case of cervical carcinoma cells. In 2011, Noh et al. founded that silibinin induced apoptotic cell death in MCF-7 cells. Angioprevention and antiangiogenic therapy are considered as efficient strategies for controlling the growth and metastasis of solid tumors as well as for other diseases involving pathological angiogenesis. Singh (2005) showed that silibinin exhibits pleiotropic antiangiogenic effects in human endothelial cells. They also observed that silibinin (a) inhibits capillary tube formation on matrigel;
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