The expression of six genes was significantly different in primary tumors compared with their matched liver metastases [CXCR4 (p < 0.001), THBS1 (p = 0.007), MMP 9 (p = 0.048), GST Pi (p = 0.050), TYMP (p = 0.042) and DPYD (p < 0.001)].
In both primary tumor and liver metastasis, the TS mRNA levels correlated significantly with the OPRT mRNA level (primary rS=0.83, P=0.00000081; liver metastasis rS=0.49, P=0.017), while the DPD mRNA level correlated significantly with the TP mRNA level rS=0.81, P=0.0000024; rS=0.63, P=0.0014; respectively).
Using a reverse transcription competitive PCR assay, we quantified DPD mRNA levels in 10 matched colorectal tumors and adjacent normal mucosae and 7 colorectal liver metastases and adjacent normal livers.