Contribution of angiogenesis to the progression of colon cancer: possible inhibitory effect of angiogenesis inhibitor TNP-470 on tumor growth and hepatic metastasis

The contribution of angiogenesis to tumor growth and hepatic metastasis of colorectal cancer was investigated by means of immunohistochemical study and in vitro and in vivo experiments. Colorectal cancer specimens from 30 patients with hepatic metastasis and 39 patients without hepatic metastasis were studied by staining with antibodies against factor VIII-related antigen. Microvessel count in patients with liver metastasis was significantly higher than in those without liver metastasis (p<0.005). The effect of TNP-470 was evaluated with in vitro and in vivo experiments using human colon cancer cell line, LM and the highly hepatic metastasis cell line, LM-H5. The effect of TNP-470 on the proliferation of the cancer cells and human umbilical vein endothelial cells (HUVECs) was examined. TNP-470 inhibited more sensitively the proliferation of HUVECs than cancer cells in vitro. IC50 was approximately 3 pg/ml in HUVECs and approximately 2 microg/ml in cancer cells. The effect of TNP-470 on the growth of xenografts and liver metastases by LM-H5 in nude mice was examined. TNP-470 (30 mg/kg) was administered by subcutaneous injection every third day for 4 weeks. TNP-470 inhibited both the growth of xenograft and the hepatic metastasis. The number of metastatic foci in the liver was 78.2+/-30.1 in the control group and 20.6+/-16.5 in the treated group. These results suggest that TNP-470 is a potent agent to inhibit tumor growth and hepatic metastasis of colon cancer.

Expression levels of thymidine phosphorylase and dihydropyrimidine dehydrogenase in various human tumor tissues

Thymidine phosphorylase (dThdPase) is the rate-limiting enzyme that metabolizes 5'-deoxy-5-fluorouridine (5'-dFUrd, doxifluridine), an intermediate metabolite of capecitabine, to the active drug 5-fluorouracil (5-FUra), while dihydropyrimidine dehydrogenase (DPD) catabolizes 5-FUra to an inactive molecule. The susceptibility of tumors to fluoropyrimidines is reported to correlate with tumor levels of these enzymes. To obtain some insight into the tumor types susceptible to fluoropyrimidine therapy, we measured expression levels of these two enzymes in various types of human cancer tissues (241 tissue samples) by the ELISA methods. DPD exists in all the cancer types studied, such as bladder, breast, cervical, colorectal, esophageal, gastric, hepatic, pancreatic, prostate, and renal cancers. Among them, the cervical, hepatic, pancreatic, esophageal, and breast cancer tissues expressed high levels of DPD (median >70 U/mg protein), while high concentrations of the dThdPase were expressed in esophageal, cervical, breast, and pancreatic cancers and hepatoma (median >150 U/mg protein). The dThdPase/DPD ratio, which was reported to correlate with the susceptibility of human cancer xenografts to capecitabine, was high in esophageal, renal, breast, colorectal, and gastric cancers (median ratio of >1.5). In any of these three parameters, the inter-patient DPD variability for each cancer type was much larger than the DPD variability among cancer types; highest/lowest ratios for dThdPase, DPD, and dThdPase/DPD were 10-321, 7-513, and 2-293, respectively. These results indicate that measurements of the three parameters, DPD, dThdPase and dThdPase/DPD, would be useful criteria for selecting cancer patients suitable for fluoropyrimidine therapy rather than for selecting cancer types.

TGF-beta1 secreted by gastric fibroblasts up-regulates CD44H expression and stimulates the peritoneal metastatic ability of scirrhous gastric cancer cells

Gastric fibroblast-derived conditioned medium and TGF-beta1 stimulated the adhesion ability of scirrhous gastric cancer cells to mesothelial cells, but not that of well-differentiated gastric cancer cells. The CD44H expression of scirrhous gastric cancer cells was significantly up-regulated by gastric fibroblast-derived CM and TGF-beta1. The stimulated adhesion ability and CD44H expression was significantly inhibited by anti TGF-beta1 neutralizing antibody. These findings suggested that TGF-beta1 secreted by gastric fibroblasts up-regulated the CD44H expression of scirrhous gastric cancer cells, which resulted in the stimulation of the adhesion ability of scirrhous gastric cancer cells to the mesothelium, and increased the peritoneal dissemination potential. These results might explain one of the reasons why scirrhous gastric carcinomas develop frequent peritoneal dissemination.

Serum CA 125 level as a predictor of peritoneal dissemination in patients with gastric carcinoma

BACKGROUND

Prediction of peritoneal dissemination is very difficult using current diagnostic tools such as computed tomography, ultrasonography, or various tumor markers. The predictive value of serum CA 125 levels for peritoneal metastasis from gastric carcinoma was studied.

METHODS

The sera from 384 patients with gastric carcinoma were measured for CA 125 titer using an immunoradiometric assay. Carcinoembryonic antigen, carbohydrate antigen 19-9, and sialyl-Tn antigen were measured in the same samples.

RESULTS

The serum CA 125 level was elevated according to the degree of peritoneal dissemination. The reference value for peritoneal dissemination was determined to be 35 U/mL, resulting in a sensitivity of 39.4%, specificity of 95.7%, and diagnostic accuracy of 90.8%. The diagnostic ability was more reliable than the other imaging modalities including computed tomography and ultrasonography and the other useful tumor markers for gastric carcinoma. The serum CA 125 level was elevated after gastrectomy for approximately 2 months, most likely due to the continuous inflammation of the peritoneum and lost predictive significance for peritoneal dissemination during this period.

CONCLUSIONS

Measurement of the serum CA 125 titer may be a powerful predictor of peritoneal metastases in patients with gastric carcinoma.