Yan-Zhen Lin

Effect of NF-κB Constitutive Activation on Proliferation and Apoptosis of Gastric Cancer Cell Lines

Objective: To observe whether there is constitutive activation of nuclear transcription factor ĸB (NF-ĸB) and its effect on proliferation and apoptosis of human gastric cancer cell lines. Methods: Nuclear/cytoplasmic protein expression of NF-ĸB was analyzed by Western blot in four different gastric cancer cell lines. Trans AMTM NF-ĸB p65 Kit was used for detecting the difference of p65 activity. The effect of PDTC (pyrrolidine dithiocarbamate), a specific inhibitor of NF-ĸB on the proliferation of gastric cancer cells, was measured by MTT (3-[4,5-dimethythiazol-2-yl]-2,5-diphenyltetrazolium bromide) method. The apoptotic rates of AGS and SGC-7901 gastric cancer cell lines were measured with flow cytometer (FCM) after treatment by PDTC. Results: The constitutive activations of NF-ĸB were identified in four gastric cancer cell lines. The expression of activated subunit of p50 was lower in AGS cell line, and higher in MKN28, MKN45 and SGC-7901 cell lines. The expression of activated subunit of p65 was lower in MKN28 and MKN45 cell lines, and higher in AGS and SGC-7901 cell lines. Both the activity of NF-ĸB and the cell proliferation were significantly inhibited in experimental group treated by PDTC, compared with control groups (p < 0.01). An increased apoptotic rate and a decreased proliferating activity were observed after the gastric cancer cells were exposed to PDTC for 24 h. Conclusions: These results suggested that the constitutive activation and the protein expression of NF-ĸB are different in gastric cancer cell lines. PDTC can inhibit NF-ĸB activity and cell proliferation, which related to an increased cell apoptosis. The results disclosed that NF-ĸB could be a potential therapeutic target for solid tumor therapy.

Effects of Linomide on growth and metastasis of implanted human gastric cancer in nude mice

AIM To elucidate the effect of angiogenesis inhibitor, Linomide, on tumor growth and metastasis in nude mice implanted with human gastric cancer. METHODS A metastatic model of gastric cancer was established using orthotopic implantation of histologically intact tumor tissues into the gastric wall of nude mice. Linomide (0, 80, 160 mg·kg(-1)) was given p.o. every day after the implantation, and the mice were sacrificed after 10 wk to detect tumor size and metastasis. The microvessel counts were measured by immunohistochemical staining using a monoclonal antibody against Human Factor VIII related antigen. RESULTS Linomide treatment significantly decreased the size of the implanted tumors (control group: 1.36 ± 0.81 cm(3) vs Linomide treated group: 0.84 ± 0.51 cm(3) and 0.62 ± 0.35 cm(3), P < 0.05 and 0.01, respectively). Additionally, an antimetastatic effect of Linomide was clearly demonstrated in a dose dependent manner: mice given 80 mg·kg(-1) Linomide developed liver metastasis in 4 of 10 cases, mice given 160 mg/kg developed metastasis in only 1 of 10 mice, while it developed in 19 of 28 mice of the control group (P < 0.05 and 0.01, respectively). The number of metastatic foci was also significantly less in the treated group. Furthermore, the microvessel counts in tumors of treated mice was reduced by 33%-42% as compared with the control tumors (P < 0.01). CONCLUSION Linomide has a strong inhibitory activity against in vivo tumor growth and metastasis of gastric cancer, effectively suppressing the growth of the primary tumor, preventing liver metastasis, and attenuating the rate of neovascularization.