Cathepsin D and carcino-embryonic antigen in serum, urine and tissues of colon adenocarcinoma patients.

BACKGROUND/AIMS: Application of neoplastic markers in early diagnosis of colorectal carcinoma has brought fresh hope to millions of sufferers. However such a marker, distinctive for this particular carcinoma and allowing its detection at a sufficiently early stage of development has not yet been found. Cathepsin D (CD) is lysosomal aspartyl proteinase. It is a component of a proteolytic cascade participating actively in neoplastic invasion as well as in metastasis formation. Carcino-embryonic antigen (CEA) is a useful marker in oncological diagnostics of colorectal cancer. CEA undergoes expression in all kinds of adenocarcinoma and is found both intercellularly and extracellularly. High concentrations of CEA in the blood serum confirm neoplastic changes in the digestive tract with high probability. The objective of this study has been to evaluate CD activity in the blood serum, urine and tumor tissues as well as in the colon biopsies which were not changed macroscopically and CEA concentration in the serum of colon adenocarcinoma, considering the extent of spread of cancer (TNM), the grade of the differentiation of cancer cell (G) as well as the tumor size. The possibility of application of CD along with CEA as markers of colon adenocarcinoma has also been examined.

METHODOLOGY

The examination included the serum and urine of 21 patients as well as 12 tissues biopsies with histopathologically confirmed colon adenocarcinoma. The reference group for the blood and urine comprised of 17 healthy controls, and for the colon adenocarcinoma tissues- samples collected from 14 people from the sites most distant from the resected tumor on the boundaries which were free of cancer cells. Activity of CD in the blood serum, urine as well as tissues was determined with a modified Greczaniuk et al. method and expressed by the amount of released tyrosine as the concentration of the activity in nmolTyr/mL/6h, whereas the specific activity was expressed in nmol Tyr/mg of protein /6h. The specific activity of CD in the urine was expressed in nmol Tyr/mg of creatinine/6h. CEA concentration in the blood serum was determined by the immunoenzymatic method (MEIA) on Axym Abbot Analyzer and was expressed in ng/mL. The protein concentration was determined by the Lowry method, and the results were expressed in mg/mL. The creatinine concentration in the urine was determined by the Jaffe method (without deproteinization) and was expressed in mg/100mL.

RESULTS

CD activity was increased in the blood serum (p < 0.0001) and tissues (p = 0.022) of colon adenocarcinoma patients in comparison to the reference group. CD specific activity (Tyr/mg of protein/6h) was significantly increased in serum but decreased in the urine (p < 0.0001) whereas the specific activity of CD (nmol Tyr/mg of creatinine/6h) was increased in the urine (p = 0.0001). CD specific activity has tendency to increase in colon adenocarcinoma tissues (p = 0.441) as compared to the reference group. By examining data in regard to TNM clinical-histopathological classification, G and the tumor size, it could be concluded that CD activity in serum and urine in colon adenocarcinoma patients depends on progress of cancer in which CD activity increases with TNM. A statistically significant increase in CEA concentration was found in the serum of colon adenocarcinoma patients, which was almost threefold higher than the in reference group. No significant differences in CEA concentration were found depending on TNM, G and tumor size.

CONCLUSIONS

The results of this study suggest that examination of CD activity and CEA concentration in serum, as well as CD activity in the urine, might be used in oncological diagnostics of colon adenocarcinoma.