Thymidine phosphorylase expression causes both the increase of intratumoral microvessels and decrease of apoptosis in human esophageal carcinomas

Thymidine phosphorylase (dThdPase)/platelet-derived endothelial cell growth factor, is expressed at higher levels in tumor tissues compared to the adj acent normal tissues in a variety of human carcinomas. The higher expressio n is associated with an increase of intratumoral microvessel density (IMVD) and an unfavorable patient prognosis. We examined the role of dThdPase in apoptosis, IMVD, P53 expression and patient prognosis of human stages II an d III esophageal squamous cell carcinomas (SCC). dThdPase expression was no ted in 52 of the 78 esophageal SCC (66.7%), regardless of tumor stages and histologic grades. Mean IMVD was 117.9 +/- 32.6 in the dThdPase-positive ca ses and 103.1 +/- 21.5 in the dThdPase-negative cases, the value being sign ificantly higher in the former (P < 0.05). Similarly, median (range) apopto tic index (AI: percentage of apoptotic cells) was significantly lower in th e dThdPase-positive SCC, 1.8 (0.4-6.5), than in the dThdPase-negative SCC, 3.7 (0.6-7.0) (P < 0.01). AI and IMVD showed a significant inverse correlat ion (r = - 0.31, P = 0.005). There was also no significant difference in th e frequency of P53 expression between the dThdPase-positive SCC and the neg ative SCC. No statistical difference was noted regarding the postoperative survival rate between the dThdPase-positive and the negative SCC. Although dThdPase expression was not associated with patient prognosis, the expressi on provided an advantage for tumor growth of human esophageal SCC, not only by increasing the intratumoral microvessels, but also attenuation of apopt osis, which might occur via a p53 gene-independent pathway.