Transcriptional gene expression profiles of HGF/SF-met signaling pathway in colorectal carcinoma

Activation of NFkappaB represents the central event in the neoplastic progression associated with Barrett's esophagus: a possible link to the inflammation and overexpression of COX-2, PPARgamma and growth factors

The molecular mechanisms responsible for the progression of malignant transformation in Barrett's esophagus (BE) are still poorly understood. This study was undertaken (1) to investigate the gene and protein expression of cyclooxygenase-2 (COX-2), peroxisome proliferator-activated receptor-gamma (PPARgamma), interleukin-8 (IL-8), hepatocyte growth factor (HGF), gastrin, and its receptor (CCK-2) in the Barrett's epithelium; (2) to analyze the activity of NFkappaB in Barrett's esophagus with low-grade dysplasia; and (3) to assess the effects of PPARgamma ligand (ciglitazone) and gastrin on cell proliferation in the cell line derived from esophageal adenocarcinoma (OE-33). COX-2, PPARgamma, IL-8, HGF, gastrin, and CCK-2 expression levels relative to the control gene encoding GAPDH were analyzed by RT-PCR and Western blot in specimens of BE with low-grade dysplasia (n = 20) and compared with that in the normal squamous esophageal mucosa from the middle portion of the esophagus (n = 20). In vitro experiments included the incubation of cell line OE-33 with ciglitazone (1-15 microM) and gastrin (100 nM). NFkappaB activity in biopsies specimens was measured by highly sensitive ELISA. COX-2, PPARgamma, IL-8, HGF, gastrin, and CCK-2 expressions were significantly increased in BE compared with normal squamous esophageal mucosa. NFkappaB activity was significantly upregulated in BE. Ciglitazone inhibited cell proliferation of OE-33 cells as assessed by BrdU and this effect was attenuated partly by gastrin. (1) COX-2, PPARgamma, HGF, gastrin, and its receptor are significantly upregulated in BE, suggesting a possible role for these factors in Barrett's carcinogenesis; (2) the increased NFkappaB activity is probably linked to increased IL-8 and COX-2 expression; and (3) PPARgamma ligands might be useful as a new therapeutic option in the prevention and treatment of Barrett's carcinoma.

Expression and significance of leptin receptor in colorectal adenocarcinoma

AIM: To investigation the expression of leptin receptor in colorectal cell lines and colorectal adenocarcinoma tissue, and the relationship between its expression, vascular proliferation and tumor cell proliferation.

METHODS: The expression of leptin receptor, CD34 and Ki67 proteins was detected by immunohistochemistry in HT29 and SW480 cells and colorectal adenocarcinoma tissues. Leptin receptor, the MVD and cell proliferation exponent were analyzed by image analysis software.

RESULTS: Leptin receptor was expressed in HT29 cells, SW480 cells and all colorectal adenocarcinoma tissue. The normal large intestine tissue also had leptin receptor, but the mean of their absorbance was lower than that of colorectal adenocarcinoma tissue (0.153±0.011 vs 0.115± 0.071, P < 0.05). The MVD and Ki67 exponent of colorectal adenocarcinoma tissue were both higher than those of normal controls (41.500±10.700 vs 31.300±11.100, P < 0.01; 0.458±0.108 vs 0.312±0.097, P < 0.01). There was a positive correlation between leptin receptor and Ki67 exponent (r = 0.388, P < 0.05). The MVD of colorectal adenocarcinoma tissue which leptin receptor expressed in blood vessel endothelial cells was higher than the negative ones (45.100±10.000 vs 37.400±10.200, P < 0.05). The correlation could not be found between leptin receptor and clinical pathologic parameters of colorectal adenocarcinoma.

CONCLUSION: Leptin may have some roles to accelerate tumor cell proliferation and vascular proliferation in colorectal adenocarcinoma tissue after it binds leptin receptor.