The Mutagenic Effect on PHB Accumulation of Acidiphilium cryptum DX1-1 / 微生物学通报

The strain Acidiphilium cryptum DX1-1 producing PHB was irradiated respectively by UV and Co60 to raise PHB production. The results indicated that the effect of UV better than using Co60. One strain of the UV mutagenized called UV60-3 has the highest PHB production yield, showing final PHB concentra- tion of 28.56 g/L, 1.45 times higher than that of original strain. FT-IR spectroscopy analysis shows that the polymers obtained from the strain DX1-1 have the same IR spectra of standard PHB. Further research about the best appropriate C/N ratio of the mutant was done. The optimum ratio of C/N was about 3.76, the final PHB concentration reaches to 30.57 g/L.

Isolation and characterization of human colorectal cancer cell subline with unique metastatic potential in the liver / 南方医科大学学报

<p><b>OBJECTIVE</b>To isolate a subclone from human colorectal cancer cell line SW480 with unique metastatic potential in the liver.</p><p><b>METHODS</b>Human colorectal cancer cells SW480 were implanted into BALB/c nude mice, and the hepatic metastatic lesions were harvested, and the tumor tissue blocks were re-implantated into nude mice for a second round of in vivo selection. The same procedure was repeated 5 times until a new cell subline, designated as SW480/M5, was established, whose biological behaviors was investigated both in vivo and in vitro.</p><p><b>RESULTS</b>After orthotopic implantation of the tumor tissue into the colon of nude mouse for 28 days, widespread loco-regional and distant metastases occurred in mice inoculated with SW480 tissue, and those inoculated with SW480/M5 tissue had hepatic metastasis only. Compared with the parental cells, SW480/M5 cells were characterized by greater clonality, reproductive activity, motor ability, invasiveness, and weaker adhesive capacity to fibronectin.</p><p><b>CONCLUSION</b>A human colorectal cancer cell subline with unique liver metastatic potential has been established by in vivo selection to serve as a new model for study ing colorectal cancer metastasis.</p>

Effect of Tiam1 overexpression on proliferation and metastatic potential of human colorectal cancer / 中华病理学杂志

<p><b>OBJECTIVE</b>To confirm the role of Tiam1 (T lymphoma invasion and metastasis 1) gene in the proliferation and metastasis of colorectal cancer.</p><p><b>METHODS</b>Proliferative and metastatic abilities of Tiam1 transfectant were investigated by subcutaneous injection of cells and surgical orthotopic transplantation (SOI) in mice.</p><p><b>RESULTS</b>The expression of Tiam1 led to a pronounced increase in HT29/Tiam1 cell growth starting from day 7, up to 2.5 fold increase of tumor volume at day 20 post injection. Tumors in the HT29/Tiam1 group receiving surgical orthotopic implantation were significantly heavier than those in HT29/mock group (t = -14.916, P < 0.01). In vivo metastasis assay by SOI showed that in HT29/Tiam1 group, 7/7 of mice developed peritoneal metastases and 4/7 had hepatic lesions. In addition, one of the seven HT29/Tiam1 group mice had tumors in lung, spleen and lymph nodes. In the HT29/mock group, only 2/7 of animals had peritoneal metastases and none produced detectable tumor in the liver.</p><p><b>CONCLUSIONS</b>Tiam1 gene plays an important role in the proliferation, invasion and metastasis of colorectal cancer. It may serve as a useful clinical marker for tumor progression and metastasis of colorectal cancer.</p>