Expression of pyrimidine nucleoside phosphorylase mRNA plays an important role in the prognosis of patients with oesophageal cancer

The dual role of thymidine phosphorylase in cancer development and chemotherapy

Thymidine phosphorylase (TP), also known as "platelet-derived endothelial cell growth factor" (PD-ECGF), is an enzyme, which is upregulated in a wide variety of solid tumors including breast and colorectal cancers. TP promotes tumor growth and metastasis by preventing apoptosis and inducing angiogenesis. Elevated levels of TP are associated with tumor aggressiveness and poor prognosis. Therefore, TP inhibitors are synthesized in an attempt to prevent tumor angiogenesis and metastasis. TP is also indispensable for the activation of the extensively used 5-fluorouracil prodrug capecitabine, which is clinically used for the treatment of colon and breast cancer. Clinical trials that combine capecitabine with TP-inducing therapies (such as taxanes or radiotherapy) suggest that increasing TP expression is an adequate strategy to enhance the antitumoral efficacy of capecitabine. Thus, TP plays a dual role in cancer development and therapy: on the one hand, TP inhibitors can abrogate the tumorigenic and metastatic properties of TP; on the other, TP activity is necessary for the activation of several chemotherapeutic drugs. This duality illustrates the complexity of the role of TP in tumor progression and in the clinical response to fluoropyrimidine-based chemotherapy.

5-Fluorouracil concentration in blood, liver and tumor tissues and apoptosis of tumor cells after preoperative oral 5’-deoxy-5-fluorouridine in patients with hepatocellular carcinoma

AIM: To study the levels of 5-fluorouracail (5-FU) in plasma, liver and tumor in patients with hepatocellular carcinoma after oral administration of 5’-deoxy-5-fluorouridine (5’-DFUR).

METHODS: Thirty-nine patients with hepatocellular carcinoma were treated with oral 5’-DFUR for more than 4 d before operation. The contents of 5-FU in plasma, liver and tumor were measured by high performance liquid chromatography (HPLC) and apoptosis of tumor cells was evaluated by in-situ TUNEL after resection of tumor.

RESULTS: The concentrations of 5-FU were 1.1 μg/mL, 5.6, 5.9, and 10.5 μg/g in plasma, the liver tissue, the center of tumor and the periphery of tumor, respectively. 5-FU concentration was significantly higher in the periphery of tumor than that in the liver tissue and the center of tumor (10.5 ± 1.6 μg/g vs 5.6 ± 0.8 μg/g, t = 21.38, P < 0.05; 10.5 ± 1.6 μg/g vs 5.9 ± 0.9 μg/g, t = 20.07, P < 0.05). 5-FU level was significantly lower in plasma than that in the liver and the tumor (1.1 ± 0.3 μg/mL vs 5.6 ± 0.8 μg/g, t = 19.63, P < 0.05; 1.1 ± 0.3 μg/mL vs 10.5 ± 1.6 μg/g, t = 41.01, P < 0.05). Apoptosis of tumor cells was significantly increased after oral 5’-DFUR compared to the control group without 5’-DFUR treatment.

CONCLUSION: There is a higher concentration of 5-FU distributed in the tumor compared with liver tissue and apoptosis of tumor cells is increased following oral 5’-DFUR compared with the control group. The results indicate that 5’-DFUR is hopeful as neo-adjuvant chemotherapy to prevent recurrence after resection of hepatocellular carcinoma.

Platelet-derived endothelial cell growth factor mediates Rho-associated coiled-coil domain kinase messenger RNA expression and promotes cell motility

BACKGROUND

Platelet-derived endothelial cell growth factor (PD-ECGF), whose expression is increased in several cancers, is an endothelial cell mitogen and has chemotactic activity in vitro and angiogenic activity in vivo. Tumors with high PD-ECGF expression tend to have frequent lymph node metastasis and are associated with poor outcome.

METHODS

We screened genes transduced by PD-ECGF transfection to the colon cancer cell line DLD-1 by using a complementary DNA microarray. Cell motility was evaluated by in vitro migration assay. Actin fiber polymerization was visualized by immunofluorescent detection of phalloidin.

RESULTS

Rho-associated coiled-coil domain kinase (ROCK1) was found to be significantly overexpressed in PD-ECGF transfectants compared with mock cells. PD-ECGF transfectants showed higher cell motility than mock cells. The parental cell, DLD-1, with recombinant PD-ECGF showed higher cell motility than that without recombinant PD-ECGF, in which motility was blocked by the neutralizing antibody of PD-ECGF or Y-27632, a specific inhibitor of ROCK1. Moreover, the actin fiber polymerization, which is a marker of activation of ROCK1, was higher in PD-ECGF transfectants than in mock cells.

CONCLUSIONS

PD-ECGF expression may be associated with cancer cell migration via activation of ROCK1. This may explain one mechanism by which tumors with high expression of PD-ECGF show aggressive behavior.

Thymidine phosphorylase expression in oral squamous cell carcinoma

Thymidine phosphorylase (TP), as an enzyme involved in DNA synthesis, catalyzes the reversible conversion of thymidine to thymine. It is also identical to the angiogenic factor, platelet-derived endothelial cell growth factor. We examined TP expression using immunohistochemistry in 66 archival samples obtained from the patients with primary oral squamous cell carcinoma (SCC) and investigated its relation to tumor vascularity, cell proliferation, apoptosis, clinicopathological features and survival. TP expression was identified in cytonucleus and/or cytoplasm in carcinomas, but was not identified in histologically normal epithelia distant to tumor in most cases. No significant difference of microvessel density (MVD) was found between the carcinomas with high TP expression (H-TP) and low TP expression (L-TP). The percentages of proliferative cells marked by Ki-67 staining in H-TP carcinomas was significantly higher than that in L-TP carcinomas (P=0.0222). The apoptotic indice (AI) in H-TP carcinomas tended to be lower than that in L-TP carcinomas (P=0.0723). Moreover, the level of TP expression was significantly correlated the pattern of tumor invasion (P=0.0146) and marginally correlated with lymph nodal metastasis (P=0.0804). Our results suggested that TP enzyme may play a role in promotion of tumor growth in oral SCC, and that its expression can be indicative of tumor aggressiveness in this tumor type.