Inhibition by transforming growth factor (34-43)-alpha, a TGF-alpha antagonist, of gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine in Wistar rats

TGF3L fusion enhances the antitumor activity of TRAIL by promoting assembly into polymers

TRAIL, a promising antitumor immuno-agent, exerted limited efficacy in clinical trials. The third disulfide loop of TGF-α (TGF3L peptide) with a very low affinity for EGFR has been reported to enhance the activity of fused antigens or cytokines. We wondered whether fusion of this peptide could enhance TRAIL activity and what the underlying mechanism for this enhancement would be. The TGF3L-TRAIL showed greatly enhanced cytotoxicity in a variety of cancer cell lines while spared normal cells unharmed. Typical apoptosis and cellular caspase activation were potently induced by TGF3L-TRAIL at the concentration levels corresponding to its cytotoxicity. TGF3L-TRAIL was able to activate both DR4 and DR5 the same as TRAIL did. It induced complete cell death in Colo205 through only one receptor when the other one was blocked, different from TRAIL-induced cell death (through DR4 dominantly). TGF3L-TRAIL cytotoxicity was not reduced in some cell lines even if both receptors are blocked simultaneously. Surprisingly, TGF3L-TRAIL self-assembled into stable polymers, which was responsible for its enhanced cytotoxicity. In human tumor xenograft mouse models, TGF3L-TRAIL showed anti-tumor activity similar to or better than TRAIL in different cancer cell types, consistent with its differing enhancement of cytotoxicity in vitro. Taken together, TGF3L fusion of TRAIL obviously enhances the anticancer activity of TRAIL by promoting assembly into polymers, which presents a novel fusion strategy for improving TRAIL function.

Review article: How useful are the rodent animal models of gastric adenocarcinoma?

Gastric cancer is the second most common cause of cancer-related mortality world-wide. In most cases, it develops via the pre-malignant stages of atrophic gastritis, intestinal metaplasia and dysplasia, following Helicobacter pylori infection of susceptible individuals. A number of rodent models have recently provided valuable insights into the host, bacterial and environmental factors involved in gastric carcinogenesis. Wild-type rodents do not develop gastric adenocarcinoma, but early studies showed that the disease could be induced in several rodent species by chemical carcinogens. More recently, it has been demonstrated that gastric adenocarcinoma can be induced in Mongolian gerbils by H. pylori infection and in C57BL/6 mice by long-term H. felis infection. These models have allowed the importance of Helicobacter virulence genes, host factors, such as gender, strain and immune response, and environmental factors, such as dietary salt, to be explored. A number of transgenic mice with alterations in various pathways, including the immune response, gastrin biosynthesis, parietal cell development, growth factors and tumour suppressors, have also provided models of various stages of gastric carcinogenesis. One model that has proved to be particularly valuable is the hypergastrinaemic INS-GAS mouse, in which gastric carcinoma develops spontaneously in old animals, but the process is greatly accelerated by Helicobacter infection.

Connective tissue growth factor induces apoptosis in human breast cancer cell line MCF-7

Connective tissue growth factor (CTGF) is a member of an emerging CCN gene family that is implicated in various diseases associated with fibro-proliferative disorder including scleroderma and atherosclerosis. The function of CTGF in human cancer is largely unknown. We now show that CTGF induces apoptosis in the human breast cancer cell line MCF-7. CTGF mRNA was completely absent in MCF-7 but strongly induced by treatment with transforming growth factor beta (TGF-beta). TGF-beta by itself induced apoptosis in MCF-7, and this effect was reversed by co-treatment with CTGF antisense oligonucleotide. Overexpression of CTGF gene in transiently transfected MCF-7 cells significantly augmented apoptosis. Moreover, recombinant CTGF protein significantly enhanced apoptosis in MCF-7 cells as evaluated by DNA fragmentation, Tdt-mediated dUTP biotin nick end-labeling staining, flow cytometry analysis, and nuclear staining using Hoechst 33258. Finally, recombinant CTGF showed no effect on Bax protein expression but significantly reduced Bcl2 protein expression. Taken together, these results suggest that CTGF is a major inducer of apoptosis in the human breast cancer cell line MCF-7 and that TGF-beta-induced apoptosis in MCF-7 cells is mediated, in part, by CTGF.

Attenuation by all-trans-retinoic acid of sodium chloride-enhanced gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine in Wistar rats

The effect of prolonged administration of all-trans-retinoic acid (RA) on sodium chloride-enhanced gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine, and the labelling and apoptotic indices and immunoreactivity of transforming growth factor (TGF) alpha in the gastric cancers was investigated in Wistar rats. After 25 weeks of carcinogen treatment, the rats were given chow pellets containing 10% sodium chloride and subcutaneous injections of RA at doses of 0.75 or 1.5 mg kg(-1) body weight every other day. In week 52, oral supplementation with sodium chloride significantly increased the incidence of gastric cancers compared with the untreated controls. Long-term administration of RA at both doses significantly reduced the incidence of gastric cancers, which was enhanced by oral administration of sodium chloride. RA at both doses significantly decreased the labelling index and TGF-alpha immunoreactivity of gastric cancers, which were enhanced by administration of sodium chloride, and significantly increased the apoptotic index of cancers, which was lowered by administration of sodium chloride. These findings suggest that RA attenuates gastric carcinogenesis, enhanced by sodium chloride, by increasing apoptosis, decreasing DNA synthesis, and reducing TGF-alpha expression in gastric cancers.