Transfection of thymidine phosphorylase cDNA to human hepatocellular carcinoma cells enhances sensitivity to fluoropyrimidine but augments endothelial cell migration.

PURPOSE

To investigate the effects on sensitivity to fluoropyrimidine and endothelial cell (EC) migration by transfection with thymidine phosphorylase (TP) cDNA to a hepatocellular carcinoma (HCC) cell line SMMC-7721.

METHODS

SMMC-7721 was transfected with pcDNA3.1/zeo (+) with human TP cDNA. TP mRNA expression was determined by RT-PCR. Sensitivity to fluoropyrimidine was determined by 3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyl-tetrazolium bromide (MTT) assay. Induction of EC migration was detected by Boyden chamber assay.

RESULTS

The construction of pcDNA3.1/zeo(+)-TP was verified by digestion with restriction endonuclease Apa1. When comparison was made between SMMC-7721 cell clone transfected with pcDNA3.1/zeo(+)-TP (S-TP) and control clone transfected with pcDNA3.1/zeo(+) (S-vector), we found that TP mRNA expression level was much higher in S-TP, being 2.09+/-0.16 vs 0.48+/-0.06 in S-vector (P < 0.01), sensitivity to 5'-deoxy-5-fluorouridine (5'-dFUrd, a prodrug of 5-fluorouracil) in S-TP was significantly enhanced compared with that in S-vector (IC(50); 56.81+/-9.85 micromol/l vs 162.25+/-11.03 micromol/l, P < 0.01), and the culture medium of S-TP possessed more potential to induce EC migration than that of S-vector (the number of ECs appearing on the outer surfaces of the membrane was 275+/-29 vs 122+/-35 per field, P < 0.01).

CONCLUSION

Sensitivity to 5'-dFUrd could be enhanced by transfection with TP cDNA for SMMC-7721 cells. However, EC migration was also promoted at the same time. Therefore, transfection with TP alone might have no potential to enhance anti-tumoral effects of fluoropyrimidine in HCC.