Thymidine phosphorylase activity in nonsmall cell lung carcinoma tissues.

Abstract

This is the first study on the quantitative assessment of thymidine phosphorylase (TP) activity in patients with nonsmall lung carcinoma. TP is identical to the platelet-derived endothelial cell growth factor with its angiogenic activity. Thus, it is believed that TP activity in tumor tissues plays an important role in disease progression. Using a sandwich enzyme immunoassay, the TP activity in lung carcinoma tissues was measured quantitatively in 39 patients with primary lung carcinoma who underwent pulmonary lobectomy between July 1999 and May 2000. The mean value of TP activity in tumor tissues was significantly higher than the level in normal lung tissues (226 U/mg protein vs. 46 U/mg protein, respectively; P < 0.0001). TP activity in normal lung tissues was high in male patients (male vs. female, respectively: 56.1 U/mg protein vs. 29.3 U/mg protein; P = 0.001) and in heavy smokers (Brinkmann index [BI] > or = 600 [57.9 U/mg protein] vs. BI < 600 [31.7 U/mg protein]; P = 0.001). Conversely, the TP activity in tumor tissues was correlated with neither gender nor smoking status. Although there was no difference in the TP activity among histologic types, well-differentiated tumors exhibited a significantly lower level of TP activity compared with the activity in both moderately and poorly differentiated tumors. However, the TP activity in tumor tissues was not correlated with disease progression. High TP activity in tumor tissues from patients with primary lung carcinoma did not reflect the malignant potential of the disease.