Distribution of metallothioneins in the brain neoplastic cells

Metallothioneins (MT) are common proteins in animal tissues. These proteins take part in the homeostasis of the ions of the metals which are necessary for the proper metabolism of the organism (zinc, copper), biosynthesis regulation and zincprotein activity (for example the activity of the zinc-dependant transcription factors) and they also take part in the detoxication of the tissue from toxic metals. Apart from these, they also protect the tissue from reactive oxygen species, radiation, electrophilic pharmacological agents used in the cancer therapy and the mutagens. The aim of this work was to obtain cellular sub-fractions of brain tumors and to separate these proteins by SDS-polyacrylamide gel electrophoresis and Western Blotting technique and to determine the level of metallothioneins and to determine the level of metallthioneins in the cellular sub-fraction. The experimental materials were the brain neoplastic tissues resected during neurosurgical procedures. The brain tumors were divided into two groups; astrocytoma G-2 and malignant gliomas (astrocytoma GM-4, glioblastoma multiforme). The cellular fractions of tumour tissues were obtained according to Clark and Nicklas and Chauveau et al. methods. The level of the metallothioneins was determined by the cadmium-hemoglobin affinity assay using the cadmium isotope (109Cd). By performing protein dissection on polyacrylamide gel (PAGE) and applying immunoidentifying technique we proved the presence of metallothioneins in all the cell sub-fractions. In GM-4 patients the total MT level increased by 12.06% whereas in the cytosol sub-fraction it increased by 17.02% in comparison with astrocytoma G-2 patients. In the mitochondrial sub-fraction the level increased by 49.09% while in the nuclear and microsomal sub-fractions the increase was by 22.38 and 8.24%, respectively.