The Effect of Different Treatments of (-)-Epigallocatechin-3-Gallate on Colorectal Carcinoma Cell Lines.

Backgroud: (-)-Epigallocatechin-3-gallate (EGCG), the major component of green tea, is well documented to induce apoptosis and cell cycle arrest in cancer by targeting multiple signal transduction pathways. However, EGCG is extremely unstable in general culture conditions and rapidly degraded. So, to what extent EGCG or which degradation products of EGCG play a role in anti-tumor is still unknown. In this study, we evaluated the effect of different treatments of EGCG on HCT116 cells. DESIGN: MTT assay was applied to evaluated the inhibitory effect of different treatments of EGCG on HCT116 cells. Cell cycle and apoptosis were performed by flow cytometry. Finally, western blot analysis was used to elucidate the molecular mechanism associated with cell cycle arrest and apoptosis. RESULTS: Compared with control, both EGCG and O-EGCG (i.e., EGCG being pre-incubated at 37°C for 3 h) significantly inhibited HCT116 cells growth. Surprisingly, we found that the inhibitory effect of O-EGCG was stronger than that of EGCG. The IC50 values of EGCG and O-EGCG were 8.75 and 5.40 µM, respectively. Cell cycle analysis showed that 20 µM of EGCG simultaneously caused cell cycle arrest at G1 and G2 phase in HCT116 cells, differing from O-EGCG which exclusively caused cell cycle arrest at G2. This result suggested that parent EGCG at the early treatment might cause cell cycle arrest at G1. As time went on, EGCG disappeared and degraded products of EGCG were formed which might cause cell cycle arrest at G2. Further studies revealed that EGCG induced cell cycle arrest at G1 by downregulation of cyclin E and cyclin D1 and upregulation of p21. On the other hand, O-EGCG induced HCT116 cells apoptosis mainly by increasing the expression of p53 and cleaved caspase-3, which might be the underlying reason why O-EGCG had stronger inhibitory effect on HCT116 cells line than EGCG. CONCLUSIONS: The pretreatment of EGCG may be an effective way to enhance its antitumor effect.

Therapeutic effects of Lactobacillus casei Qian treatment in activated carbon-induced constipated mice.

In the present study, the therapeutic effects of Lactobacillus casei Qian (LC-Qian), the key microorganism in Tibetan yak yoghurt, on activated carbon-induced constipation were determined in vivo. ICR mice were treated with LC-Qian for nine days by oral administration. The body weight, defecation status, gastrointestinal transit and defecation time of mice were assessed, and the serum levels of motilin (MTL), gastrin (Gas), endothelin (ET), somatostatin (SS), acetylcholinesterase (AChE), substance P (SP) and vasoactive intestinal peptide (VIP) were further evaluated. Bisacodyl was used as the positive control. The time until the first black stool defecation following carbon intake of the normal, control, 100 mg/kg bisacodyl-treated, Lactobacillus bulgaricus (LB)-treated, LC-Qian (L)-and LC-Qian (H)-treated mice was 93, 231, 121, 194, 172 and 157 min, respectively. Following treatment with LC-Qian, the gastrointestinal transit was increased to 52.4% [LC-Qian (L)] and 65.8% [LC-Qian (H)], while that in the group treated with the common lactic acid bacteria of LB was 40.3%. The MTL, Gas, ET, AChE, SP and VIP serum levels were significantly increased and levels of SS were reduced in mice following LC-Qian treatment compared with those in the control mice (P<0.05). Reverse transcription quantitative polymerase chain reaction indicated that LC-Qian raised the c-Kit, GDNF as well as SCF mRNA expression levels and reduced the TRPV1 and NOS expression levels in tissue of the small intestine in mice. These results suggested that lactic acid bacteria prevent constipation in mice, among which LC-Qian was the most effective.

Increased preventive effect on colon carcinogenesis by use of resistant starch (RS3) as the carrier for polysaccharide of Larimichthys crocea swimming bladder.

The preventive effect of polysaccharide of Larimichthys crocea swimming bladder (PLCSB) and the increase of this effect by use of resistant starch (RS3) as the carrier for PLCSB on azoxymethane (AOM) and dextran sulfate sodium (DSS)-inducing colon carcinogenesis in C57BL/6 mice has been studied. RS3 microspheres carrying PLCSB (RS3 + PLCSB) were produced and evaluated as a potentially improved colon carcinogenesis therapy for this study. The body weight, colon length, and colon weight of mice were determined, and colonic tissues were histologically observed. The serum levels of proinflammatory cytokines and the inflammation and apoptosis-related genes in colonic tissue were also tested. The PLCSB or RS3 + PLCSB significantly suppressed AOM and DSS-induced body weight loss, colon length shortening and decreased the colon weight to length ratio. PLCSB or RS3 + PLCSB reduced the levels of the serum pro-inflammatory cytokines IL-6, IL-12, TNF-α, and IFN-γ to a greater extent compared with the control mice, and the levels of RS3 + PLCSB were more close to the normal mice than PLCSB treated mice. Histopathological examination of sections of colon tissues showed that the RS3 + PLCSB group recovered well from colon carcinogenesis; however, the tissue sections of the stachyose + starch could reduce the necrosis degree. PLCSB significantly induced apoptosis in tissues of mice (p < 0.05) by up-regulating Bax, caspase-3, and caspase-9, and down-regulating Bcl-2. The expression of genes associated with inflammation-related NF-κB, iNOS, and COX-2 genes, was significantly down-regulated, and IκB-α was up-regulated (p < 0.05). These results suggest that PLCSB is a potent preventive against in vivo colon carcinogenesis and that PLCSB with an RS3 carrier could increase the preventative effect in mice.