A Systematic Review of the Prevalence of Germline BRCA mutations in North Asia Breast Cancer Patients.

OBJECTIVE: The BRCA1/2 mutation status testing is the global standard of care for breast cancer patients with a family history of cancer. BRCA1/2 mutations are known to be ethno-specific. For some ethnic groups of the Northern Asia (Buryats, Yakuts, Altaians, Tuvans, Khakasses, etc.) the founder mutations in the BRCA1/2 genes have not been revealed. This systematic review was conducted to assess the prevalence of BRCA1/2 mutation in breast cancer patients inhabiting Eastern Europe and Northern Asia (or Siberia). METHODS: A total of 23,561 studies published between 2014 and 2024 were analyzed, of which 55 were included in the review. The literature search was conducted using RusMed, Cyberleninka, Google Scholar, eLibrary, NCBI databases (n=5) and conference papers. RESULTS: The founder mutations (c.5266dupC and/or c.181T>G) of BRCA1 gene that were frequently observed in the Slav peoples were also identified in Chechens, Armenians, Bashkirs, Ukrainians, Mordovians, Mari, Kabardians, Tatars, Uzbeks, Kyrgyz, Ossetians, Khanty indigenous peoples and Adygs. For Chechens, Kabardians, Ingush, Buryats, Khakasses, Sakha, Tuvans and Armenians, rare pathogenic variants of the BRCA1/2, ATM, СНЕК2, BRIP1, NBN, PTEN, TP53, PMS1, XPA, LGR4, BRWD1 and PALB2 genes were found. No data are available about the frequency of pathogenic BRCA1/2 mutations for ethnic groups, such as the Udmurts, Komi, Tajiks, Tabasarans, and Nogais indigenous people. CONCLUSION: This is the first systematic review that provides the spectrum of BRCA mutations in ethnic groups of breast cancer patients inhabiting Eastern Europe and Northern Asia. It has been shown that the mutations are ethnospecific (varied widely within groups) and not all groups are equally well studied. Further studies on the ethnic specificity of BRCA gene mutations are required.

Development of Novel Monoclonal Antibodies for Evaluation of Transmembrane Prostate Androgen-Induced Protein 1 (TMEPAI) Expression Patterns in Gastric Cancer.

Transmembrane prostate androgen-induced protein 1 (TMEPAI) is a single-span membrane protein, functionally involved in transforming growth factor beta signaling pathway. The particular protein presented in cells in three isoforms, which differs in the length of the soluble N-terminal extracellular domain, making it challenging for the immunochemical recognition. By using quantitative real-time polymerase chain reaction, we identified significant upregulation of PMEPA1 gene expression in malignant tissues of patients with gastric adenocarcinoma. The main part of commercially available anti-TMEPAI antibodies are having polyclonal nature or not suitable for immunocytochemical localization of target protein in tissue specimens. Hence, we decide to generate a set of novel rat monoclonal antibodies (mAb) directed against conservative C-terminal cytoplasmic epitope. Immunoblotting analysis showed that monoclonal antibodies, 2E1, 6C6, and 10A7 were able to recognize specifically target protein in transiently transfected HEK293T and CHO-K1 cells. Especially established mAb, named 10A7, showed the excellent binding ability to target protein in immunohistochemistry. By using developed antibodies, we observed pronounced expression of TMEPAI in normal gastric epithelial cells while tumor cells from gastric adenomas, and adenocarcinoma samples were mostly negative for target protein expression. Also, we found that gastric epithelium cells lose the TMEPAI expression concurrently with severe dysplasia progression, which probably caused by a mechanism involving specific microRNA.

Hypomethylation of human-specific family of LINE-1 retrotransposons in circulating DNA of lung cancer patients.

Circulating DNA has recently gained attention as a fast and non-invasive way to assess tumor biomarkers. Since hypomethylation of LINE-1 repetitive elements was described as one of the key hallmarks of tumorigenesis, we aimed to establish whether the methylation level of LINE-1 retrotransposons changes in cell-surface-bound fraction of circulating DNA (csbDNA) of lung cancer patients. Methylated CpG Island Recovery Assay (MIRA) coupled to qPCR-based quantitation was performed to assess integral methylation level of LINE-1 promoters in csbDNA of non-small cell lung cancer patients (n=56) and healthy controls (n=44). Deep sequencing of amplicons revealed that hypomethylation of LINE-1 promoters in csbDNA of lung cancer patients is more pronounced for the human-specific L1Hs family. Statistical analysis demonstrates significant difference in LINE-1 promoter methylation index between cancer patients and healthy individuals (ROC-curve analysis: n=100, AUC=0.69, p=0.0012) and supports the feasibility of MIRA as a promising non-invasive approach.

Ascorbic acid glucoside reduces neurotoxicity and glutathione depletion in mouse brain induced by nitrotriazole radiosensitazer.

AIM: To investigate the potential of the anti-oxidant ascorbic acid glucoside (AA-2G) to modulate neurotoxicity induced by high doses of nitrotriazole radiosensitizer. MATERIALS AND METHODS: Male and female C56Bl/6xCBA hybrid mice aged 8-14 weeks (weight 18-24 g) were used. Nitrotriazole drug radiosensitizer sanazole at a high dose of 2, 1 g/kg was per os administered to induce neurotoxicity at mice. Ascorbic acid glucoside was given 30 min before the sanazole administration. Serum ascorbic acid, brain glutathione level, as well as behavioral performance using open field apparatus were measured. RESULTS: Administration of high (non-therapeutic) doses of the nitrotriazole drug sanazole results in neurotoxicity in mice as evidenced from behavioral performance, emotional activity and depletion of the cellular antioxidant, glutathione, in the brain. The serum levels of ascorbic acid was also found reduced in high dose sanazole treated animals. Per os administration of ascorbic acid glucoside significantly reduced the neurotoxicity. This effect was associated with the prevention of glutathione depletion in mouse brain and restoring the ascorbic acid level in serum. CONCLUSION: Administration of ascorbic acid glucoside, but not ascorbic acid, before sanazole administration protected from sanazole-induced neurotoxicity by preventing the decrease in the brain reduced glutathione level and providing high level of ascorbic acid in plasma.

Potentialities of aberrantly methylated circulating DNA for diagnostics and post-treatment follow-up of lung cancer patients.

To date, aberrant DNA methylation has been shown to be one of the most common and early causes of malignant cell transformation and tumors of different localizations, including lung cancer. Cancer cell-specific methylated DNA has been found in the blood of cancer patients, indicating that cell-free DNA circulating in the blood (cirDNA) is a convenient tumor-associated DNA marker that can be used as a minimally invasive diagnostic test. In the current study, we investigated the methylation status in blood samples of 32 healthy donors and 60 lung cancer patients before and after treatment with neoadjuvant chemotherapy followed by total tumor resection. Using quantitative methylation-specific PCR, we found that the index of methylation (IM), calculated as IM = 100 × [copy number of methylated/(copy number of methylated + unmethylated gene)], for the RASSF1A and RARB2 genes in the cirDNA isolated from blood plasma and cell-surface-bound cirDNA was elevated 2- to 3-fold in lung cancer patients compared with healthy donors. Random forest classification tree model based on these variables combined (RARB2 and RASSF1A IM in both plasma and cell-surface-bound cirDNA) lead to NSCLC patients' and healthy subjects' differentiation with 87% sensitivity and 75% specificity. An association of increased IM values with an advanced stage of non-small-cell lung cancer was found for RARB2 but not for RASSF1A. Chemotherapy and total tumor resection resulted in a significant decrease in the IM for RARB2 and RASSF1A, in both cirDNA fractions, comparable to the IM level of healthy subjects. Importantly, a rise in the IM for RARB2 was detected in patients within the follow-up period, which manifested in disease relapse at 9 months, confirmed with instrumental and pathologic methods. Our data indicate that quantitative analysis of the methylation status of the RARB2 and RASSF1A tumor suppressor genes in both cirDNA fractions is a useful tool for lung cancer diagnostics, evaluation of cancer treatment efficiency and post-treatment monitoring.

RARß2 gene methylation level in the circulating DNA from blood of patients with lung cancer.

Alterations in the patterns of DNA methylation are among the earliest and most common events in tumorigenesis. Epigenetic changes were shown to be detectable in DNA, circulating in blood (cirDNA) of cancer patients, indicating the resources to create the minimally invasive diagnostic tests based on tumor-specific DNA markers. RARß2 methylation level was significantly increased in plasma cirDNA and cell surface-bound cirDNA (csb-cirDNA) from patients with non-small cell lung cancer compared with healthy individuals (7620 and 1083 copies/ml in the csb fractions, 3589 and 1068 copies/ml in the blood plasma; P=0.003 and 0.001). The cell-bound-to-cell-free RARß2 methylation ratio was found to be elevated in patients with non-small cell lung cancer compared with control (2.12 and 1.01, respectively; P=0.023). RARß2 methylation level in csb-cirDNA and plasma cirDNA was higher in stage III patients compared with stage I-II patients (P=0.02 and 0.03). In the subgroup of patients with squamous cell carcinoma, RARß2 methylation level in the cbs-cirDNA was higher compared with patients with adenocarcinoma (P=0.04). Epigenetic alterations of tumor suppressor gene RARß2 in the total cirDNA (plasma cirDNA and csb-cirDNA) were found to be associated with lung cancer progression. The data obtained indicate that cirDNA-based testing provides a valuable source for subsequent verification of methylated DNA markers for lung cancer diagnostics and prognosis.

Production of nitric oxide by hypoxic radiosensitizer sanazole.

AIM: In this work we investigated the ability of hypoxia-selective radiosensitizer--sanazole to produce nitric oxide (NO). METHODS: NO formation was determined by spectophotometric method in the reaction with sanazole and oxyhemoglobin. In suspensions of lymphoma EL-4 and mastocytoma P 8815 cell NO production was estimated indirectly as nitrite concentration in the supernatant fraction. RESULTS: Transformation of oxyhemoglobin by sanazole to methemoglobin suggested the dissociation of nitro group in aqueous solution and denitration of molecules. Addition of sanazole to hypoxic tumor cell suspension resulted in the increase of nitrite content in tissue culture medium. CONCLUSION: Presented data suggest the ability of sanazole to produce NO that may be important in a probable mechanism for antitumor and immunomodulating properties of this radiosensitizer.