Chromatin analysis in human endometrial adenocarcinoma before and after treatment with 6-methyl-17-hydroxyprogesterone acetate (MPA)

Summary

Some molecular and ultrastructural characteristics of chromatin (propidium iodide intercalation into DNA during thermal denaturation, DNA content per nucleus and its hydrolysis kinetics, eu-heterochromatin ratio) were studied in the cells of endometrial adenocarcinomas following oral treatment with 6-methyl-17-hydroxyprogesterone acetate (MPA) at a dose of 1 g/day for 12 days.

Ultrastructurally, before treatment the nuclei of tumour cells were often irregularly shaped and exhibited a mostly dispersed chromatin (euchromatin). In addition, the distribution of DNA content per cell was clearly abnormal, reaching ploidy levels of 16c. From a physicochemical standpoint, both the thermal denaturation and the HCl-hydrolysis of DNA revealed a high lability of chromatin.

After progestin treatment, nuclear morphology appeared to approach normality, and large areas of heterochromatin reappeared which, after staining with propidium iodide, could be seen as strongly fluorescent points. DNA showed a higher resistance to thermal denaturation, especially evident at temperatures exceeding 70° C. Also the HCl-hydrolysis curves showed that, particularly with regard to short (< 20 min) or protracted (> 140 min) hydrolysis times, DNA was less easily hydrolyzed than before MPA-treat-ment.

A clearcut modification could be observed with regard to the DNA content per cell, high ploidy levels disappearing and values being less dispersed.

On the whole, these findings demonstrated an effect of the drug on tumor cells, particularly affecting chromatin, at least with regard to the parameters examined.