Clinical chemistry of polyamines

Mucosal polyamine metabolism in the columnar lined oesophagus

Mucosal ornithine decarboxylase activity and polyamine content has been proposed as a possible marker for malignant potential in gastrointestinal mucosa. Polyamine content and histological findings were examined in 107 pairs of endoscopic biopsy specimens taken from gastric fundus, fundic and specialised Barrett's oesophagus and Barrett's adenocarcinoma. The content of putrescine (median nmol/mg protein, range) the primary product of ornithine decarboxylase showed a progressive increase from gastric fundus (0.41, 0.15-1.5); fundic (0.45, 0.01-4.08); specialised Barrett's oesophagus (0.54, 0.01-2.0); dysplastic columnar lined oesophagus (0.56, 0.31-3.1) to adenocarcinoma (1.23, 0.29-8.98). Adenocarcinoma putrescine content was significantly greater than gastric fundus (p < 0.018) and fundic (p < 0.03). Mucosal spermine, spermidine, and total polyamine values were greater in gastric fundus than fundic, specialised Barrett's oesophagus, and dysplastic columnar lined oesophagus (all p < 0.001) suggesting failure to further metabolise putrescine to its higher polyamines in the metaplastic epithelium. Although metaplastic columnar lined oesophagus shows significant differences in polyamine metabolic activity from the stomach the important distinction between specialised and dysplastic columnar lined oesophagus cannot be made by measuring the polyamine content.

Diamine oxidase (DAO) activity increase in sera of tumor patients: An unreliable marker

Circulating diamine oxidase (DAO) (EC 1.4.3.6) activity was determined in the sera of patients with different malignant tumors. The increase in this activity only partially reflected tumor activity so it is presumably unreliable as a diagnostic marker. The increase in activity may be linked to the tumor location: the lung and intestine are rich in DAO so the rise cannot be considered a characteristic consequence of the tumor's activity. Besides, increases in DAO activity have also been observed in non-neoplastic diseases.

Differences in polyamine metabolism between carcinomatous and uninvolved human breast tissues

The polyamine biosynthetic enzymes ODC and SAMDC show higher activity in carcinomatous human breast tissue than in uninvolved tissue of the same breast; the interconversion enzyme PAO shows significantly lower activity in carcinomatous than uninvolved tissue. The polyamine metabolism in carcinomatous human breast tissue thus appears to differ from that in uninvolved tissue. Intracellular polyamine concentrations, particularly spermine, are high in carcinomatous tissue. This increase and that of the biosynthetic enzymes suggest that a higher polyamine concentration is needed for carcinomatous cell growth. If this is the case, the lower PAO activity in carcinomatous tissue may be explained as a mechanism that conserves the high intracellular polyamine concentration.

Elevation of monoacetylated polyamines in human breast cancers

Normal tissues contain only trace amounts of monoacetylated polyamines. N1-Acetylspermidine is present in high concentrations in mouse liver cells damaged by hepatotoxins and is also found in specialised cells of the hamster epididymis. In the present study human breast cancers were analysed for the presence of monoacetylated polyamines because N1-acetylspermidine is selectively elevated in human colorectal cancers. Free and monoacetylated polyamines (N1-acetylspermidine, N8-acetylspermidine and N1-acetylspermine), measured by high-performance liquid chromatography, were expressed as nmol/g wet wt of breast cancers (n = 54) or normal breast tissue (n = 15). Putrescine and monoacetylated polyamines were absent from normal breast tissue. Mean total content of monoacetylated polyamines in breast cancers 14.9 +/- 5.3 (S.E.) exceeded the mean total content of free polyamines (8.3 +/- 1.0) in normal breast tissue. Detectable levels of at least two of the monoacetylated polyamines were found in all breast cancers: N1-acetylspermidine was present in 51 (13.1 +/- 6.3), N8-acetylspermidine in 32 (0.6 +/- 0.1) and N1-acetylspermine in 28 tumours (1.2 +/- 0.3). There was no correlation between monoacetylated polyamine content of breast cancers and factors known to affect survival, i.e. tumour size, histological grade, oestrogen receptor status and node status. Monoacetylated polyamines are present in human breast cancers but not in normal breast tissue, implying that polyamine catabolism in breast cancers differs from that in normal breast tissue.