Do the expression of CD44, apoptosis and thymidylate synthase inhibition rate correlate with the efficacy of chemotherapy in colorectal cancer?

BACKGROUND

Tegafur-uracil(UFT;TAIHO Pharmaceutical Co.Ltd, Tokyo, Japan) is commonly used to treat digestive cancers. However, the inhibitors of metastasis in this agent have not been fully examined. To investigate a cell adhesion molecule, CD44, which may very well contribute to the pathogenesis of metastasis, we examined the association of CD44 and the thymidylate synthase inhibition rate(TSIR) with prognosis, and examined the expression of apoptosis in patients who were administrated tegafur-uracil before surgery for colorectal cancer.

MATERIALS AND METHODS

This study included 66 patients who underwent curative resection of colorectal cancer. In these patients, tegafur-uracil(600 mg) was orally administered every day for 3 to 7 days before surgery, and Tegafur-uracil (400 mg) was orally administered every day for 2 years after surgery. CD44 and apoptosis were detected immunohistochemically and by the TUNNEL method, respectively. The TSIR was calculated from the total TS level, and free TS levels by modified Spears' method using fresh tumor tissue specimens.

RESULTS

The TSIR of non-recurrent patients was significantly higher than that of recurrent patients(p < 0.05). The 5-year survival rate in CD44-low grade positive/negative patients (81.6%) was significantly higher than that in CD44-high grade positive patients (46.4%) (p < 0.005). The 5-year survival rate in apoptosis-high grade positive patients (89.7%) was significantly higher than that in apoptosis-low grade positive/negative patients(46.4%) (p < 0.001). With respect to the relationship between CD44 and apoptosis, the proportion of apoptosis-high grade positive patients among CD44-low grade positive/negative patients (55.3%) was significantly higher than that among CD44-high grade positive patients(28.6%) (p < 0.05). In the multivariate analysis, the CD44 expression was suggestive of an independent prognostic factor.

CONCLUSION

Based on our results for TSIR, Tegafur-uracil may induce apoptosis of tumor cells in patients by the inhibition of thymidylate synthase. It was suggested that CD44 expression could be used as a possible independent predictor of survival. In addition, it was suggested that UFT, via the inhibition of CD44 expression caused the inhibition of distant metastasis.