Mitochondrial DNA Changes in Respiratory Complex I Genes in Brain Gliomas.

Mitochondria are organelles necessary for oxidative phosphorylation. The interest in the role of mitochondria in the process of carcinogenesis results from the fact that a respiratory deficit is found in dividing cells, especially in cells with accelerated proliferation. The study included tumor and blood material from 30 patients diagnosed with glioma grade II, III and IV according to WHO (World Health Organization). DNA was isolated from the collected material and next-generation sequencing was performed on the MiSeqFGx apparatus (Illumina). The study searched for a possible relationship between the occurrence of specific mitochondrial DNA polymorphisms in the respiratory complex I genes and brain gliomas of grade II, III and IV. The impact of missense changes on the biochemical properties, structure and functioning of the encoded protein, as well as their potential harmfulness, were assessed in silico along with their belonging to a given mitochondrial subgroup. The A3505G, C3992T, A4024G, T4216C, G5046A, G7444A, T11253C, G12406A and G13604C polymorphisms were assessed as deleterious changes in silico, indicating their association with carcinogenesis.

Mitochondrial DNA Changes in Genes of Respiratory Complexes III, IV and V Could Be Related to Brain Tumours in Humans.

Mitochondrial DNA changes can contribute to both an increased and decreased likelihood of cancer. This process is complex and not fully understood. Polymorphisms and mutations, especially those of the missense type, can affect mitochondrial functions, particularly if the conservative domain of the protein is concerned. This study aimed to identify the possible relationships between brain gliomas and the occurrence of specific mitochondrial DNA polymorphisms and mutations in respiratory complexes III, IV and V. The investigated material included blood and tumour material collected from 30 Caucasian patients diagnosed with WHO grade II, III or IV glioma. The mitochondrial genetic variants were investigated across the mitochondrial genome using next-generation sequencing (MiSeq/FGx system-Illumina). The study investigated, in silico, the effects of missense mutations on the biochemical properties, structure and functioning of the encoded protein, as well as their potential harmfulness. The A14793G (MTCYB), A15758G, (MT-CYB), A15218G (MT-CYB), G7444A (MT-CO1) polymorphisms, and the T15663C (MT-CYB) and G8959A (ATP6) mutations were assessed in silico as harmful alterations that could be involved in oncogenesis. The G8959A (E145K) ATP6 missense mutation has not been described in the literature so far. In light of these results, further research into the role of mtDNA changes in brain tumours should be conducted.

Characteristics of Fluorescent Intraoperative Dyes Helpful in Gross Total Resection of High-Grade Gliomas-A Systematic Review.

Background: A very important aspect in the treatment of high-grade glioma is gross total resection to reduce the risk of tumor recurrence. One of the methods to facilitate this task is intraoperative fluorescence navigation. The aim of the study was to compare the dyes used in this technique fluorescent intraoperative navigation in terms of the mechanism of action and influence on the treatment of patients. Methods: The review was carried out on the basis of articles found in PubMed, Google Scholar, and BMC search engines, as well as those identified by searched bibliographies and suggested by experts during the preparation of the article. The database analysis was performed for the following phrases: "glioma", "glioblastoma", "ALA", "5ALA", "5-ALA", "aminolevulinic acid", "levulinic acid", "fluorescein", "ICG", "indocyanine green", and "fluorescence navigation". Results: After analyzing 913 citations identified on the basis of the search criteria, we included 36 studies in the review. On the basis of the analyzed articles, we found that 5-aminolevulinic acid and fluorescein are highly effective in improving the percentage of gross total resection achieved in high-grade glioma surgery. At the same time, the limitations resulting from the use of these methods are marked-higher costs of the procedure and the need to have neurosurgical microscope in combination with a special light filter in the case of 5-aminolevulinic acid (5-ALA), and low specificity for neoplastic cells and the dependence on the degree of damage to the blood-brain barrier in the intensity of fluorescence in the case of fluorescein. The use of indocyanine green in the visualization of glioma cells is relatively unknown, but some researchers have suggested its utility and the benefits of using it simultaneously with other dyes. Conclusion: The use of intraoperative fluorescence navigation with the use of 5-aminolevulinic acid and fluorescein allows the range of high-grade glioma resection to be increased.

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.

Influence of metallothioneins on zinc and copper distribution in brain tumours.

Metallothioneins take part in the homeostasis of the ions of the metals which are necessary for the proper metabolism of the organism (zinc, copper), in biosynthesis regulation of the zinc-containing proteins and also in the detoxication of metals from the tissues. They also protect the tissue from the effects of free radicals, radiation, electrophilic pharmacological agents used in the cancer therapy and from mutagens. The experimental materials were brain astrocytomas, benign gliomas and malignant gliomas. The levels of the metallothionein were determined by cadmium-haemoglobin affinity assay using the cadmium isotope (109Cd). The values of zinc and copper were determined by means of atomic absorption spectrophotometry. In our studies, the level of metallothioneins in the group of malignant neoplasms was slightly higher than the level of these proteins in the group of benign neoplasms. The correlation coefficient of the studied parameters proved an interrelation between the levels of zinc and copper and the content of metallothioneins. In malignant neoplasms, the level of zinc showed a positive relationship with the metallothionein level, whereas the copper content showed an inverse relationship. There was a statistical difference, but no significant difference, in the levels of copper between malignant and benign groups.

Metallothioneins and microelements in brain tumours.

Metallothioneins 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 of the zinc containing proteins. They also take part in the detoxication of metals from the tissues. Besides,they protect the tissue from the effects of free radicals, radiation, electrophilic pharmacologic agents used in the cancer therapy and from mutagens. The experimental materials were brain astrocytomas, benign gliomas (astrocytoma G-2) and malignant gliomas (glioblastoma multiforme GM-4). The levels of the metallothionein were determined by cadmium-hemoglobin affinity assay using the cadmium isotope (109Cd). The value of zinc and copper were determined by means of atomic absorption spectrophotometry. In our studies, the level of metallothioneins in the group of malignant neoplasms was slightly higher than the level of these proteins in the group of benign neoplasms. There was a statistical difference, but there is no significant difference in the levels of copper between malignant and benign groups.