Ilex kudingcha C.J. Tseng (Kudingcha) has in vitro anticancer activities in MCF-7 human breast adenocarcinoma cells and exerts anti-metastatic effects in vivo

Ilex kudingcha C.J. Tseng (Kudingcha) is a traditional Chinese drink consumed in East Asia. The present study evaluated the in vitro anticancer effects of Kudingcha in MCF-7 human breast adenocarcinoma cells using a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay. At a concentration of 200 μg/ml, Kudingcha inhibited the growth of the MCF-7 cells by 81%. This was a greater degree of inhibition than that observed at concentrations of 100 and 50 μg/ml (58 and 19%, respectively). To elucidate the inhibitory mechanisms underlying the anticancer effect of Kudingcha in cancer cells, the expression of genes associated with apoptosis and inflammation were measured using RT-PCR. Kudingcha significantly induced apoptosis, as determined by 4,6-diamidino-2-phenylindole (DAPI) staining, by upregulating Bax, caspase-3 and caspase-9, and downregulating Bcl-2. The expression of the NF-κB, iNOS and COX-2 genes associated with inflammation was significantly decreased (P<0.05) by Kudingcha, thus demonstrating its anti-inflammatory properties. Kudingcha has been reported to exhibit inhibitory effects of tumor metastasis induced in 26-M3.1 colon carcinoma cells in BALB/c mice. The results demonstrated that Kudingcha had potent in vitro anticancer effects; it induced apoptosis, had anti-inflammatory activities and exerted in vivo anti-metastatic effects. Additionally, the anticancer, anti-inflammatory and anti-metastatic effects of Kudingcha were stronger at high concentrations than at low concentrations.


Introduction
Ilex kudingcha C.J. Tseng (Kudingcha) is a bitter tea of Chinese origin. Kudingcha has been consumed traditionally as a type of herbal tea in China and South Eastern Asia (1). Ilex kudingcha is one of the main plants that produces Kudingcha in China. Certain studies have investigated its chemical composition and pharmaceutical functions, which demonstrated the numerous functional compositions of Kudingcha and the functional effects of those compositions, such as the antioxidant effect (2). It has been reported that Kudingcha is rich in polyphenolic compounds and that it demonstrates potent antioxidant activities in vitro (3,4). It also has been demonstrated that the major phenolic compounds in Kudingcha are caffeoylquinic acid (CQA) derivatives. CQA derivatives are natural functional compounds isolated from a variety of plants, which possess a broad range of pharmacological properties, including antioxidant, hepatoprotectant, antibacterial, antihistaminic, anticancer, neuroprotective and other biological effects (5,6).
Apoptosis induction in cancer cells is initially identified by morphological changes, including cell shrinkage, membrane blebbing, chromatin condensation and nuclear fragmentation (7). Apoptosis is an important defense against cancer that involves the elimination of potentially harmful cells. Numerous diseases have been associated with dysregulated apoptotic processes that ultimately lead to the inhibition of cell death and propagation of diseases, such as cancer (8).
A previous epidemiological study showed that chronic inflammation predisposes individuals to certain types of cancer (9). Hallmarks of inflammation-related cancers include the presence of inflammatory cells and mediators in tumor tissues, tissue remodeling and angiogenesis, similar to that observed during chronic inflammatory responses and tissue repair. The study of mechanisms underlying inflammation-related cancer has been focused on the early stages of cancer (10).
Previously, Kudingcha was shown to demonstrate strong in vitro anti-cancer effects in human nasopharyngeal carcinoma cells (11). In the present study, the anti-cancer and anti-metastatic effects of Kudingcha were further examined. MCF-7 human breast adenocarcinoma cells were treated

Ilex kudingcha C.J. Tseng (Kudingcha) has in vitro anticancer activities in MCF-7 human breast adenocarcinoma cells and exerts anti-metastatic effects in vivo
with Kudingcha and the molecular mechanisms underlying the consequent anticancer effects were studied. Changes in the activities of Kudingcha were evaluated at different concentrations and the anti-metastatic effects were assessed in mice with tumors propagated by 26-M3.1 colon carcinoma cells. RT-PCR to measure mRNA expression. Total RNA was isolated from the MCF-7 human breast adenocarcinoma cells using TRIzol reagent (Invitrogen, Carlsbad, CA, USA), according to the manufacturer's instructions. The RNA was digested with RNase-free DNase (Roche, Basel, Switzerland) for 15 min at 37˚C and purified using an RNeasy kit (Qiagen, Hilden, Germany), according to the manufacturer's instructions. cDNA was synthesized from 2 µg total RNA by incubation at 37˚C for l h with avian myeloblastosis virus (AMV) reverse transcriptase (GE Healthcare, Little Chalfont, Buckinghamshire, UK) with random hexanucleotides, according to the manufacturer's instructions. The sequences of the primers that were used to specifically amplify the genes of interest are shown in Table I. Amplification was performed in a thermal cycler (Eppendorf, Hamburg, Germany). The PCR products were separated in 1.0% agarose gels and visualized using ethidium bromide (EtBr) staining (13). Statistical analysis. Data are presented as the mean ± SD. Differences between the mean values for individual groups were assessed using a one-way ANOVA with Duncan's multiple range test. P<0.05 was considered to indicate a statistically significant difference. SAS version 9.1 (SAS Institute Inc., Cary, NC, USA) was used for statistical analysis.

Results
In vitro anticancer effect of Kudingcha on MCF-7 cells. The anticancer effects of Kudingcha on the MCF-7 cells were evaluated using an MTT assay. The growth inhibitory rates of the MCF-7 cells treated with the varying concentrations of Kudingcha are shown in Table II. When solutions of the Kudingcha were administered to the MCF-7 cells, the growth inhibitory rates observed at concentrations of 50, 100 and 200 µg/ml were 19, 58 and 81%, respectively (P<0.05). These results demonstrated that Kudingcha had marked anti-proliferative effects on the MCF-7 cells. In addition, it was observed that the higher the concentration of Kudingcha, the stronger the anticancer effects.      Inflammation-related gene expression of NF-κB, IκB-α, iNOS and COX-2. The present study also determined whether the anticancer actions of Kudingcha were associated with the inhibition of NF-κB, IκB-α, iNOS and COX-2 gene expression. As shown in Fig. 3, the mRNA expression of NF-κB and IκB-α was reduced in the MCF-7 cells treated with 200 µg/ml Kudingcha solution. Kudingcha significantly modulated the expression of the genes associated with inflammation. The mRNA expression of NF-κB was decreased, while IκB-α mRNA expression levels were increased. Additionally, the mRNA expression of COX-2 and iNOS was gradually decreased in the presence of Kudingcha depending on the concentrations. These observations indicate that Kudingcha may help prevent cancer in the early stages by increasing anti-inflammatory activities. Overall, the results of this experiment demonstrated that a higher concentration of Kudingcha had a stronger anti-inflammatory effect on the human breast adenocarcinoma cells than lower concentration solutions.

Discussion
Apoptosis is a fundamental cellular event, and understanding its mechanisms of action will aid in harnessing this process for use in tumor diagnosis and therapy (15). In a healthy cell, the anti-apoptotic protein Bcl-2 is expressed on the outer mitochondrial membrane surface (16). Apoptosis results from the activation of caspase family members that act as aspartate-specific proteases (17). Cytochrome c and procaspase-9 processing is highly dependent on caspase-3, thus, this caspase is in a central position as a regulator of the essential apoptotic pathways in cancer cells (18). Caspase-3 has also been reported to play a role as an amplifier of apoptotic signals (i.e., by cleaving Bcl-2) (19). Additionally, anticancer mechanisms underlying the effect of Kudingcha on human cancer cells involve the induction of apoptosis by increasing the number of apoptotic bodies, regu-   lating the mRNA expression of Bax and Bcl-2 and promoting anti-inflammatory effects by downregulating iNOS and COX-2 gene expression. COX-2 has been suggested to play an significant role in colon carcinogenesis, and NOS, along with iNOS, may be a good target for the chemoprevention of colon cancer (20). NF-κB is one of the most ubiquitous transcription factors that regulates the expression of genes required for cellular proliferation, inflammatory responses and cell adhesion (21). These mechanisms may be involved in the anticancer effects of Kudingcha in cancer cells. Based on the results of the MTT assay and the expression patterns of pro-apoptotic genes observed in the present study, we concluded that cancer cells treated with Kudingcha underwent apoptosis. With similar results to these findings, the anticancer effects of Kudingcha in human nasopharyngeal carcinoma cells were evaluated in a previous study using MTT assay and RT-PCR analysis (11). Metastasis is defined as the spread of cancer cells from one organ or area to another adjacent organ or location (22). Malignant tumor cells are considered to have the capacity to metastasize. Cancer occurs once cells in a tissue are genetically damaged in a progressive manner, resulting in cancer stem cells possessing a malignant phenotype. Once the tumor cells come to rest in another site, they penetrate the vessel walls, continue to multiply and eventually form another tumor. Colon 26-M3.1 carcinoma cells have been used to evaluate anti-metastasis effects in vivo (23).
In conclusion, the present study used various in vitro experimental methods, including MTT assays, DAPI staining and RT-PCR assays, to evaluate the anticancer effects of Kudingcha. A mouse model bearing tumors produced by 26-M3.1 colon carcinoma cells was also assessed to study the in vivo effects of Kudingcha. Overall, Kudingcha demonstrated potent in vitro and in vivo anti-cancer activities, particularly for combating in vivo tumor metastasis. The functional contents of Kudingcha are important for augmenting these anticancer effects. A high concentration solution of Kudingcha increased the anticancer properties observed in the present study. However, the active compounds of Kudingcha require identification and evaluation in future studies.