Enzyme Patterns and Flow Cytometric DNA Measurements in Colorectal Hyperplastic Polyps and Tubular Adenomas Less than Five Millimeters

Abstract

Glucose-6-phosphate dehydrogenase (G₆PD) activity, lactate dehydrogenase (LD) activity, and cytometric flow measurement of nuclear size and cell cycle distributions were registered in biopsy specimens from adenomas and hyperplastic polyps less than 5 mm. The G₆PD and LD activities in adenomas, 36.8 ± 4 U/g protein and 1580 ± 163 U/g, respectively, were significantly higher than in hyperplastic polyps, 17.9 ±2.6 U/g and 1080 ±107 U/g, or in normal mucosa, 14.7 ±0.8 U/g and 1174 ± 56 U/g, respectively. G₆PD activity was significantly higher in adenomas with moderate (44 ± 5.8 U/g) than in those with mild (32 ± 5.9 U/g) dysplasia, in contrast to LD. No difference in enzyme activity was observed between hyperplastic polyps and normal mucosa. The growth of adenomas and hyperplastic polyps was not significantly different during the 2 years of follow-up study before biopsy specimens were taken. Increased nuclear size, unrelated to grade of dysplasia, was registered in 12 of 20 adenomas, in 1 of 10 hyperplastic polyps, and in 2 of 42 specimens from normal mucosa. Adenomas and normal mucosa from individuals with adenomas showed a significantly increased number of cells in S-phase. The values were 10.2 ± 3% and 8.8 ± 4%, respectively. Normal control value was 6.8 ± 2.2%. An increased number of cells in G₂-phase was observed only in adenomas (6.9 ± 2.7% compared with 4.9 ± 1% in controls). None of the adenomas showed aneuploidy. The results showed for the first time increased activity of enzyme markers of malignancy independent of the size of polyps and the growth rate in adenomas compared with hyperplastic polyps or normal mucosa. The increased activity correlated with the tendency to increased nuclear size and the number of cells in S- and G₂-phase (proliferative compartment). The significance of an increased number of cells in S-phase in normal mucosa from individuals with adenomas needs further investigation.

Key Words:

• Adenomas
• Colonoscopy
• DNA flow cytometry
• Enzymology
• Epidemiology
• glucose-6-phosphate dehydrogenase
• histology
• hyperplastic polyps
• lactate dehydrogenase