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Reversibility of acid and alkaline deoxyribonuclease deficiency in malignant tumor cells
Abstract:
The nature of DNAse deficiency, which appears to be characteristic for malignant tumor cells, was investigated by the histochemical lead nitrate technique under various experimental conditions. Reappearance of distinct alkaline and acid DNAse activity was observed on the periphery of spontaneously occurring tumor necrosis, at early stages of the in vitro induced tumor necrosis, in necrotic tumor cells after in vivo irradiation and after in vitro treatment with different compounds. A membrane releaser did not reactivate DNAses in viable tumor cells, whereas the homogenate from tumor tissue inhibited DNAses in normal rat liver. These findings indicate that alkaline and acid DNAse deficiency in malignant tumor cells is a reversible phenomenon. This reversal of enzymatic activity has different histochemical and chronological patterns and specific reactivating factors for each DNAse. The masking effect of DNAse activity in malignant tumor cells is probably linked to natural enzyme inhibitors and its reversal to early stages of tumor necrosis.
Insights
Malignant tumor cells exhibit DNAse deficiency, but this enzymatic activity can reappear. This DNAse (deoxyribonuclease) deficiency is reversible, particularly during early tumor necrosis, suggesting a link to enzyme inhibitors.
Area of Science:
- Biochemistry
- Oncology
- Histochemistry
Background:
- Malignant tumor cells often display a deficiency in deoxyribonuclease (DNAse) activity.
- This deficiency is thought to be a characteristic feature of cancerous cells.
Purpose of the Study:
- To investigate the nature of DNAse deficiency in malignant tumor cells.
- To explore the conditions under which DNAse activity can be restored.
Main Methods:
- Utilized the histochemical lead nitrate technique for DNAse detection.
- Examined DNAse activity under various experimental conditions, including in vitro and in vivo models.
- Assessed the effects of specific compounds and tissue homogenates on DNAse activity.
Main Results:
- Distinct alkaline and acid DNAse activity reappeared in necrotic tumor cells under several conditions.
- Reactivation was observed during spontaneous and induced tumor necrosis, post-irradiation, and after compound treatment.
- Tumor homogenate inhibited normal rat liver DNAse, while a membrane releaser did not reactivate DNAse in viable tumor cells.
Conclusions:
- DNAse deficiency in malignant tumor cells is a reversible phenomenon.
- The reversal of DNAse activity follows specific patterns and requires distinct reactivating factors.
- The masking of DNAse activity is likely due to natural enzyme inhibitors, with reversal linked to early necrosis stages.