Experimental in vivo and in vitro study of inhibitory effect of extract from taraxacum mogonon on human poorly differentiated gastric cancer / 肿瘤研究与临床

ABSTRACT

Objective To investigate inhibitory effect and mechanism of extract from taraxacum mogonon (ETM) on human poorly differentiated gastric cancer MKN45 cells and their model nude mice tumors. Methods Human poorly differentiated gastric cancer MKN45 cells cultured in vitro were divided into the control group and the experimental group. The experimental group was treated with different concentrations of ETM, while the control group was treated with phosphate buffered saline (PBS). The tumor cell growth was examined by methyl thiazolyl tetrazolium(MTT).Cell apoptosis was detected by flow cytometry (FCM). The expression of Survivin mRNA was detected by reverse transcription polymerase chain reaction (RT-PCR), and the protein expression of Survivin was detected by Western blot. The nude mouse model with poorly differentiated gastric cancer was established with MKN45 cells. Successful models of nude mice were divided into the experimental group and the control group according to random number table. ETM 0.4 ml (100 mg/ml) was injected into abdominal cavity of the nude mice in the experimental group, while only equal dose of 0.9 % NaCl solution was injected in the control group, every 3 days for once, 42 days in total. The weight and volume changes of transplantable tumors were observed. The protein expression of Survivin in transplantable tumors was examined by immunohistochemistry(IHC) method. Results ETM could inhibit the cell proliferation and promote apoptosis of MKN45 cells in a dose-dependent and time-dependent way when its concentration reached 0.2 μmol/L (P< 0.05). The expression of Survivin mRNA and Survivin protein was down regulated in a dose-dependent way in the experimental group. Survivin mRNA expression in the experimental group with 0.1,0.2,0.4,0.8, 1.6 μmol/L of ETM and in the control group was 0.18±0.04, 0.14± 0.03, 0.11±0.01, 0.08±0.04, 0.06±0.02 and 0.19±0.03 respectively (F = 132.35, P< 0.05); Survivin protein expression in the experimental group in 0.1, 0.2, 0.4, 0.8, 1.6 μmol/L of ETM, and in the control group was 0.86±0.03, 0.60±0.05, 0.43±0.01, 0.22±0.01, 0.14±0.03 and 0.92±0.06 respectively (F= 76.57, P< 0.05). The difference of experimental group was statistically significant when concentration of ETM reached 0.2 μmol/L or above compared with the control group (P< 0.05). Nude mouse experiment showed that the tumor inhibition rate was (60.3±3.2) % in the experimental group. The volume and weight of transplantable tumor in the experimental group was(326± 27)mm3and(0.31±0.13)g,which was obviously lower than that in the control group[(843±14) mm3and (0.78±0.25) g]. The difference was statistically significant (t= 3.94,P =0.043;t= 3.27,P = 0.037). IHC experiment results showed that positive cell count of Survivin protein in the experimental group was obviously less than that in the control group(28±11 vs.152±20;t =4.32,P =0.029). Conclusions ETM has an obvious inhibitory effect on human poorly differentiated gastric cancer MKN45 cell and its nude mouse tomor model. The mechanism may be related with down-regulation of Survivin expression caused by ETM.