[Expression of thymidine phosphorylase in primary colorectal cancer and liver metastasis-relationship between mRNA levels in cancer cells and protein levels in cancerous tissue]

To compare mRNA levels in cancer cells and protein levels in cancerous tissue in terms of the expression of thymidine phosphorylase(TP).The materials were resected specimens of primary colorectal cancer(n=84)and synchronous liver metastasis(n=15). The expressions of TP mRNA in cancer cells was quantified by reverse-transcriptase polymerase chain reaction(RT-PCR)using cells obtained by microdissection of paraffinembedded specimens(Danenberg tumor profiling method). The protein level of TP was determined by enzyme-linked immunosorbent assay(ELISA).There was a weak relationship between TP mRNA levels and TP protein levels in primary colorectal cancers(p=0.04), but these factors did not correlate with each other in liver metastases. There was no relationship between primary colorectal lesions and synchronous liver metastases in terms of TP mRNA levels and TP protein levels. In relation to the efficacy of 5-fluorouracil(or UFT)/Leucovorin, the mRNA level of the primary lesion was marginally higher in the order of patients with PD(n=11), SD(n=3), and CR/PR(n=4)(p=0.05). However, the TP protein level did not correlate with therapeutic efficacy.The different methods of determining the expression of TP in colorectal cancer specimens do not correlate with each other and may cause different therapeutic results after 5-fluorouracil-based chemotherapy.