Thymidine phosphorylase and dihydropyrimidine dehydrogenase expression in hepatocellular carcinoma and metastatic liver cancer

Thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD) are considered to be key enzymes affecting the prognosis for patients with various cancers. We tried to prove the correlation of TP and DPD expression in hepatocellular carcinoma (HCC) and liver metastasis. We quantified TP and DPD levels by an enzyme-linked immunosorbent assay (ELISA) in the tumor (T) and adjacent normal tissue (N) obtained from 8 HCC patients, and 11 liver metastasis patients together with 9 of their primary cancers. TP levels were higher in the primary cancer, liver metastasis, and HCC compared with each adjacent tissue. TP levels were higher in HCC than in liver metastasis, and TP levels in the adjacent tissues of HCC were also higher than those in adjacent tissues of liver metastasis. TP levels were higher in liver metastasis than in primary cancer, and TP levels in adjacent tissues of liver metastasis were also higher than those in adjacent tissues of primary cancer. However, there were no differences in TP T/N ratio between HCC and liver metastasis, and between primary cancer and liver metastasis. DPD levels were lower in the liver metastasis compared with the adjacent liver tissues, and DPD levels in liver metastasis or its adjacent liver tissues were higher than those in primary cancer or its adjacent tissues. There were no differences in DPD T/N ratio between HCC and liver metastasis, and between primary cancer and liver metastasis. Thus, we demonstrated that TP was highly expressed in liver malignancy. We may be able to increase the success of anticancer chemotherapy for liver malignancy while decreasing the side effects by analysis of T/N ratios in TP, DPD, and TP/DPD in addition to TP expression.