The significance of 5'-nucleotide phosphodiesterase isozymes in the diagnosis of liver carcinoma

National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines for use of tumor markers in liver, bladder, cervical, and gastric cancers

BACKGROUND

Updated National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines for the use of tumor markers in the clinic have been developed.

METHODS

Published reports relevant to use of tumor markers for 4 cancer sites--liver, bladder, cervical, and gastric--were critically reviewed.

RESULTS

Alpha-fetoprotein (AFP) may be used in conjunction with abdominal ultrasound for early detection of hepatocellular carcinoma (HCC) in patients with chronic hepatitis or cirrhosis associated with hepatitis B or C virus infection. AFP concentrations >200 microg/L in cirrhotic patients with typical hypervascular lesions >2 cm in size are consistent with HCC. After a diagnosis of HCC, posttreatment monitoring with AFP is recommended as an adjunct to imaging, especially in the absence of measurable disease. Although several urine markers have been proposed for bladder cancer, none at present can replace routine cystoscopy and cytology in the management of patients with this malignancy. Some may, however, be used as complementary adjuncts to direct more effective use of clinical procedures. Although carcinoembryonic antigen and CA 19-9 have been proposed for use gastric cancer and squamous cell carcinoma antigen for use in cervical cancer, none of these markers can currently be recommended for routine clinical use.

CONCLUSIONS

Implementation of these recommendations should encourage optimal use of tumor markers for patients with liver, bladder, cervical, or gastric cancers.

Flow cytometric DNA and 5'-nucleotide phosphodiesterase in endometrium

One hundred endometrium specimens have been studied with flow cytometry for DNA analysis (FCDA) and a proliferative enzyme marker, 5'-nucleotide phosphodiesterase (5'-NPD). FCDA data showed that aneuploidy was present in only 5 of 40 cancer specimens. However, with corrected histograms, a higher DNA value was observed in the G2/M (6%) of all cancer compared with noncancer specimens (4%). Thus, FCDA can be a useful diagnostic aid for endometrial cancer. The determination of 5'-NPD was done with a quenching method based on the use of 5'-(5-iodo-3-indoxyl)-thymidine phosphodiester as a substrate and 4',6-diamidino-2-phenylindole for DNA. This method could qualitatively define which population of the cell cycle had a higher enzyme level and also quantitatively gave the enzyme units per cell. It was found that 12.5% of all cancer specimens had 5'-NPD activity in the G0/G1 cells and 87.5% in the S and/or G2/M cells, whereas in the noncancer specimens 5'-NPD was found in 28.5% of the G0/G1 cells and 71.5% of the specimens had 5'-NPD in the S and/or G2/M cells. Furthermore, the concentration of 5'-NPD was found to be five times higher in the G2/M cells of the cancer specimens than that in the noncancer specimens. However, in the hyperplasia specimens, the activity was only two times higher in the same cell cycle fraction than in the normal specimens. The results of this investigation provided for the first time evidence that this exonuclease activity alters in the cell cycle fractions and that a decrease in the enzyme activity in G0/G1 cells and an increase in G2/M cells may be a useful marker for neoplastic development in human endometrial cancer.

5'-Nucleotide phosphodiesterase isozyme-V as a marker for liver metastases in breast cancer patients

A 2-year prospective study testing 258 breast cancer patients for the presence of 5'-nucleotide phosphodiesterase isozyme-V (5'-NPD-V) as a marker for liver metastases was undertaken. Despite the difficulty associated with such a study in obtaining data from biopsy (only 12 patients) and autopsy (only 18 patients), the 5'-NPD-V test correctly predicted confirmed liver metastases in 39 of 41 patients (95%). Of this group, 25 patients had abnormal liver scans at the time the 5'-NPD-V test was positive (64%). In 11 of 39 patients 5'-NPD-V was found positive before liver scans. In the majority of patients, 5'-NPD-V fluctuated between positive and negative during follow-up. While such transiently positive values may be related to treatment, they should be interpreted conservatively as liver proliferation until confirmed otherwise. Throughout the 2-year study only seven patients with nonmalignant hepatic diseases had consistent positive values (2.7%). As an indicator of liver metastases 5'-NPD-V is more specific than other liver function tests. It is also important to note that 14 patients received early chemotherapy because attention was directed toward the diagnosis of liver metastases by this test.

Tissue specificity of human phosphodiesterase. I. Blood serum

Human blood serum was found to contain two enzymes which hydrolyze various phosphate diester and phosphonate ester bonds. The enzymes were isolated by butanol extraction, ammonium sulfate precipitation, column chromatography and gel electrophoresis. Zymograms showed that one of these enzymes is serum alkaline phosphatase and the other is a 'true' phosphodiesterase I. Serums of 25 persons showed no polymorphisms for either activity. Alkaline phosphatase hydrolyzes phenolic thymidine 5'-nucleotide esters readily, but phenylphosphonate esters very poorly. Serum phosphodiesterase I prefers phenylphosphonate esters to nucleotide diesters, and has no detectable monoesterase activity.