Screening peptides binding specifically to colorectal cancer cells from a phage random peptide library.

The aim of this study was to screen for polypeptides binding specifically to LoVo human colorectal cancer cells using a phage-displayed peptide library as a targeting vector for colorectal cancer therapy. Human normal colorectal mucous epithelial cells were applied as absorber cells for subtraction biopanning with a c7c phage display peptide library. Positive phage clones were identified by enzyme-linked immunosorbent assay and immunofluorescence detection; amino acid sequences were deduced by DNA sequencing. After 3 rounds of screening, 5 of 20 phage clones screened positive, showing specific binding to LoVo cells and a conserved RPM motif. Specific peptides against colorectal cancer cells could be obtained from a phage display peptide library and may be used as potential vectors for targeting therapy for colorectal cancer.

[Screening peptides binding specifically to large intestinal cancer LoVo cells from phage random peptide library].

OBJECTIVE: To screen the polypeptides specifically binding to human large intestinal cancer LoVo cells from a phage-displayed peptide library for potential use as targeting vectors for large intestinal cancer therapy. METHODS: With the LoVo cells as the target cells and human normal large intestinal mucosal epithelial cells as the absorber cells for subtraction biopanning from a c7c phage-display peptide library, the positive phage clones were identified by enzyme-linked immunosorbent assay (ELISA) and immunofluorescence detection. The amino acid sequences of the identified peptides were deduced by DNA sequencing. RESULTS: After 3 rounds of screening, 5 positive phage clones showing specific binding to LoVo cells and containing conserved motif RPMP were obtained from the 20 randomly selected clones. CONCLUSION: Specific peptide against large intestinal cancer cells can be obtained from a phage-display peptide library for use as potential vectors for targeting therapy of large intestinal cancer.

[Expression of proliferating cell nuclear antigen in severely damaged small intestinal mucosa due to high-dose 5-FU exposure].

OBJECTIVE: To detect the expression of proliferating cell nuclear antigen (PCNA) in severely damaged intestinal mucosa due to high-dose 5-FU exposure. METHODS: Thirty-two adult C57BL/6J mice were subjected to daily intraperitoneal high-dose 5-FU injection at 150 mg/kg for 5 consecutive days, and on days 1, 3, and 5, the mice were sacrificed to obtain the small intestinal tissue for HE straining and immunohistochemistry for detecting PCNA expression. Another 8 mice with intraperitoneal PBS injection served as the control group. RESULTS: High-dose 5-FU exposure of the mice resulted in severe intestinal mucous damage, with complete destruction of the villi and crypts and significantly increased cells positive for PCNA expression (P<0.01). CONCLUSION: High-dose 5-FU treatment can significantly increase the PCNA index, and the cells expressing PCNA can be closely associated with regeneration of the severely damaged mucosa due to the exposure.

[Effect of L-Arginine on intestinal mucosal injury of rats with severe abdominal infection].

OBJECTIVE: To investigate the effect of L-Arginine on intestinal mucosal injury of rats with severe abdominal infection. METHODS: Rats received cecal ligation and puncture (CLP) to reproduce sepsis model. A total of 18 Wistar rats were divided into two groups randomly (each n=9): L-Arginine group and model group. Three hundred mg/kg of L-Arginine was injected into the abdomen in rats of L- Arginine group after CLP. Model group received equal volume of normal saline. Blood sample was harvested and the serum levels of nitric oxide (NO) and inducible nitric oxide synthase (iNOS) were determined at 24 hours after operation in both groups. The histopathological change of intestinal mucosa was observed under light microscope and mucosa damage index was determined. RESULTS: The intestinal mucosal damage was observed both in model group and L- Arginine group after CLP, but the injury was milder in L- Arginine group. There was significant difference in mucosa injury index between L-Arginine group and model group (3.4+/-0.6 vs. 4.1+/-0.5, P<0.05). The serum level of NO [(76.1+/-26.2) micromol/L vs. (87.3+/-16.7) micromol/L, P>0.05] and iNOS [(30.6+/-7.4) U/L vs(44.4+/-6.6) U/L, P<0.01] in L-Arginine group were lower than those in model group. CONCLUSION: L-Arginine could protect against intestinal mucosal injury and depress the serum level of iNOS in severe abdominal infection of rats.