Drosophila p53 isoforms have overlapping and distinct functions in germline genome integrity and oocyte quality control

p53 gene family members in humans and other organisms encode a large number of protein isoforms whose functions are largely undefined. Using Drosophila as a model, we find that a p53B isoform is expressed predominantly in the germline where it colocalizes with p53A into subnuclear bodies. It is only p53A, however, that mediates the apoptotic response to ionizing radiation in the germline and soma. In contrast, p53A and p53B are both required for the normal repair of meiotic DNA breaks, an activity that is more crucial when meiotic recombination is defective. We find that in oocytes with persistent DNA breaks p53A is also required to activate a meiotic pachytene checkpoint. Our findings indicate that Drosophila p53 isoforms have DNA lesion and cell type-specific functions, with parallels to the functions of mammalian p53 family members in the genotoxic stress response and oocyte quality control.

p53 and EGFR gene mutations in malignant tumors of the lung

Relevance: Increased incidence of lung cancer globally and in Kazakhstan, lack of screening in hereditary cases, high mortality, and low survival of patients necessitate the study of the molecular genetic causes of the disease. At present, gene mutation studies for lung cancer diagnostics are expanding. However, many gene mutations revealed remain undercovered in the scientific literature, and there is not enough data on their prognostic and diagnostic value. The purpose of the study was to discover the specifics of the р53 gene mutations and reveal the EGFR exon 19 deletions and exon 21 L858R mutations in malignant tumors of the lung of various histogenesis. Methods: The mutations were studied in tumors (200 samples) and adjacent tissue (200 samples) of patients with lung cancer (squamous cell carcinoma (SCC) and adenocarcinoma (ADC) of the lung) by polymerase chain reaction (PCR), electrophoresis, and EcoR1- and Pst1-restriction of samples after p53 gene fragments and cDNA amplification and mRNA revertase treatment. Another 263 lung cancer samples were evaluated by real-time PCR for EGFR exon 19 deletions and EGFR exon 21 L858R mutations. Results: The p53 gene was not expressed in 50% of SCC and adenocarcinoma of the lung samples. Restriction revealed p53 mRNA mutations in 100% of SCC and 75% of ADC samples. p53 exon-intron 5-6 was mutated in 50% of ADC and 70% of SCC samples, exon-intron 7-9 – in 60% of SCC cases. EGFR exons 19 and 21 mutations found in 65 of 263 lung tumor samples were associated with increased sensitivity to EGFR tyrosine kinase inhibitors. Conclusion: The p53 gene mutations revealed in most samples of SCC and ADC of the lung could be used to diagnose lung cancer and predict its severity. The identified EGFR mutations allow predicting the effectiveness of targeted therapy

NEW POTENTIAL TREATMENT FOR BRAIN GLIOMA

According to the latest statistics, brain gliomas are the most common cause of death from CNS tumors. Brain gliomas are also ranked as the second (after stroke) cause of brain surgery The mortality rate from gliomas is high and sometimes reaches 80 %. It is because the tumor grows from undifferentiated cells, which causes its peracute development and malignant transformation. Symptoms of glioma occur at stages 3 and 4, when all treatment is symptomatic, and operations are palliative. In this regard, it is necessary to develop and introduce methods for non-surgical glioma treatment. These methods include the use of antisense oligonucleotides, optogenetics, and oncolytic viruses. The aim of antisense oligonucleotides is to replace a section in a glioma cell genome with a foreign one, which disrupts cell division and leads to apoptosis and necrosis of the entire tumor. Optogenetics excludes the introduction of substances into the body. It provides a certain light signal to glioma cells, which also suppresses the growth of an undifferentiated tumor. Oncolytic viruses are genetically modified viruses that identify tumor cells, penetrate into them and start a cascade of apoptotic reactions Despite all success, such methods are still studied at the laboratory level, their implementation in practical medicine is slow and cautious. However, insufficient knowledge retards the widespread use of potentially promising and effective drugs. Scientists around the world are developing methods to treat brain gliomas at different stages of their development. This article reflects modern achievements of scientists and neurosurgeons, describing new methods for brain glioma treatment. Key words: brain glioma, optogenetics, antisense oligonucleotides, oncolytic viruses, p53 gene. Согласно последним данным статистики, глиомы мозга являются наиболее частой причиной смертей от онкологии центральной нервной системы, а также занимают второе место по частоте как причина хирургических вмешательств на головной мозг, уступая инсультам. Смертность от глиом высока и порой достигает 80 %. Причина этого заключается в том, что опухоль растет из недифференцированных клеток, что обусловливает её молниеносный рост и быстрое озлокачествление. Симптомы глиомы возникают на 3–4 стадии развития, когда все лечение направлено на ликвидацию симптомов, а операции носят паллиативный характер. В связи с этим необходима разработка и внедрение методов по нехирургическому лечению глиом. Такими методами являются использование антисмысловых олигонуклеотидов, оптогенетика, применение онколитических вирусов. Суть использования антисмысловых олигонуклеотидов заключается в замене участка генома клетки глиомы на инородный, попавший извне, что нарушает деление клеток и приводит к апоптозу и некрозу всей опухоли. Оптогенетика исключает введение веществ в организм и заключается в подаче определенного светового сигнала на глиозные клетки, что также тормозит рост недифференцированной опухоли. Онколитические вирусы – это генномодифицированные вирусы, которые определяют опухолевые клетки, проникают в них и запускают каскад апоптотических реакций. Несмотря на все успехи, данные методы продолжают изучаться на уровне лабораторий, их внедрение в практическую медицину происходит медленно и со страхом. Однако недостаточная изученность тормозит широкое применение потенциально перспективных и эффективных лекарств. Учеными мира разрабатываются методы, позволяющие лечить глиомы мозга на разных стадиях их развития. Данная статья отображает современные достижения ученых и нейрохирургов в поисках возможности применения такого рода методов. Ключевые слова: глиома мозга, оптогенетика, антисмысловые олигонуклеотиды, онколитические вирусы, ген р53.

Anticancer and Gene Expression Analysis of Piper nigrum Extract on Colon Cancer Cell Lines

One of the most prevalent malignancies among geriatrics is colorectal cancer (CRC), which starts to develop in the forms of genetic syndromes in young adults. The Piper nigrum is one important common spice used in the household having anticancer activities. The current study aims to evaluate P. nigrum seed extracts potency as anticancer against CRC cell line (COLO205). The extract is used to elucidate the MTT assay, DNA damage studies (COMET assay), Acridine Orange/Ethidium Bromide dual staining, cell death, cell cycle arrest using Flow cytometry, and regulation of Bcl-2, Bax & P53 gene regulation. To check the cell cytotoxicity by MTT assay methanolic extract was used. To evaluate anticancer activity the sample was extracted in methanol. RT-PCR was used to elevate gene expression studies of Bcl-2, Bax, and P53. In the dose-dependent mode, the extract inhibited the growth of COLO205 cells and the IC50 value was calculated at 48.2 μg/ml. The DNA fragmentation induced by apoptosis was the primary reason for the cell toxicity as observed by DNA damage studies & AO/EB dual staining technique. The extract concentration ranging from 40 & 80 μg/ml remarkably increased the proportion of cells in the S & G2/M phase. Cells at the late-apoptotic stage were found to be in the range of 22% - 57%. The Bax and P53 were upregulated and Bcl-2 was downregulated when treated with the extract. From this investigation underlying the mechanism of CRC was found to be P. nigrum extract caused to induce apoptosis and upregulation of tumor suppressor gene downregulation of apoptosis-suppressing gene bcl-2.

Discovery of Novel Small Molecule HDAC1, 2, 3 Inhibitors -- Combined Receptor-Based and Ligand-Based Virtual Screening Strategy

Aims: To investigate and validate the potential drug target to HDAC1. Background: Human histone deacetylase 1 (HDAC1) can catalyze the deacetylation of histones belongs to the family of human histone deacetylases (HDACs). As an amide hydrolase HDAC1 plays a key role in the development of many serious cancers such as prostate cancer, gastric cancer, lung cancer, esophageal cancer, colon cancer, and breast cancer. Therefore, HDAC1 inhibitors, promoting the transcription of a series of key genes such as the p53 gene and inhibiting the development of cancer through various downstream mechanisms, have great potential for the treatment of cancer. Objective: To discover new skeleton HDAC1 inhibitors efficiently and conveniently with therapeutic potential for cancer. Method: Based on the crystal structure of HDAC1, through the combination of receptor-based and ligand-based virtual screening from the commercial compound library, the top-ranked compounds are selected for purchase through binding modes analysis, and their activities were verified through in vitro HDAC1 inhibitory biological experiments Results: Based on LeDock, 5ICN shown good distinguishing ability and was used as the receptor. According to the results of the LeDock docking scoring from receptor-based virtual screening, 69 compounds with binding energy less than -7.5 kcal/mol were obtained and used for ligand-based virtual screening. A total of 21 novel compounds with high potential HDAC1 inhibitory activity were collected by combining the similarity searching (NN) and the multinomial Naive Bayes machine learning model (NB) methods. Through binding modes analysis, 10 compounds with different structures with potential HDAC1 inhibitory activity were selected and screened HDAC1 inhibitory in vitro. May267 showed moderate HDAC1 inhibitory activity, and the inhibition rate was 48% at a concentration of 20 μM. Conclusion: This study discovers novel small molecule HDAC1 inhibitors by combined receptor-based and ligand-based virtual screening strategy, which provides an efficient method for the discovery of other small molecule drugs. May267 shows moderate HDAC1 inhibitory activity, which can be further optimized as a lead compound. However, it still has the problem of poor kinase selectivity to be solved.

Efficient Generation of P53 Biallelic Mutations in Diannan Miniature Pigs Using RNA-Guided Base Editing

The base editing 3 (BE3) system, a single-base gene editing technology developed using CRISPR/Cas9n, has a broad range of applications for human disease model construction and gene therapy, as it is highly efficient, accurate, and non-destructive. P53 mutations are present in more than 50% of human malignancies. Due to the similarities between humans and pigs at the molecular level, pig models carrying P53 mutations can be used to research the mechanism of tumorigenesis and improve tumor diagnosis and treatment. According to pathogenic mutations of the human P53 gene at W146* and Q100*, sgRNAs were designed to target exon 4 and exon 5 of the porcine P53 gene. The target editing efficiencies of the two sgRNAs were 61.9% and 50.0%, respectively. The editing efficiency of the BE3 system was highest (about 60%) when C (or G) was at the 5th base. Puromycin screening revealed that 75.0% (21/28) and 68.7% (22/32) of cell colonies contained a P53 mutation at sgRNA-Exon5 and sgRNA-Exon4, respectively. The reconstructed embryos from sgRNA-Exon5-5# were transferred into six recipient gilts, all of which aborted. The reconstructed embryos from sgRNA-Exon4-7# were transferred into 6 recipient gilts, 3 of which became pregnant, resulting in 14 live and 3 dead piglets. Sequencing analyses of the target site confirmed 1 P53 monoallelic mutation and 16 biallelic mutations. The qPCR analysis showed that the P53 mRNA expression level was significantly decreased in different tissues of the P53 mutant piglets (p < 0.05). Additionally, confocal microscopy and western blot analysis revealed an absence of P53 expression in the P53 mutant fibroblasts, livers, and lung tissues. In conclusion, a porcine cancer model with a P53 point mutation can be obtained via the BE3 system and somatic cell nuclear transfer (SCNT).

Multiple Time Delays Induced Dynamics of p53 Gene Regulatory Network

p53 dynamics plays an important role in determining cell arrest or apoptosis upon DNA damage response. In this paper, based on a p53 gene regulatory network composed of its core regulator ATM, Mdm2 and Wip1, the effect of multiple time delays in transcription and translation of Mdm2 and Wip1 gene expression on p53 dynamics are investigated through theoretical and numerical analyses. The stability of the positive equilibrium point and the existence of Hopf bifurcation are demonstrated through analyzing the associated characteristic equation of the corresponding linearized system in five cases. Detailed numerical simulations and bifurcation analyses are performed to support the theoretical results. The results show that with the increase of a time delay, the positive equilibrium point becomes unstable, and the p53 dynamics presents an oscillating state. These results reveal that time delay has a significant impact on p53 dynamics and may provide a useful insight into developing anti-cancer therapy.

Mutations of p53 gene in canine sweat gland carcinomas probably associated with UV radiation

Introduction Apocrine sweat gland carcinomas (ASGCs) are rare malignant skin tumours in dogs and humans. The literature published so far focuses mostly on the clinico-epidemiological aspect of these tumours, but little is known about their pathogenesis. In this study we aimed to determine whether the p53 gene is involved in the carcinogenesis of the apocrine sweat gland in dogs and whether ultraviolet radiation (UV) is related to it. Material and Methods Forty canine ASGCs were submitted to laser capture microdissection to isolate neoplastic cells, from which DNA was subsequently extracted. PCR amplification and sequencing of p53 exons 2–8 was then performed, followed by computer analysis of the obtained sequences. Results Sixteen mutations within the p53 gene were found in 13 tumours. The mutations involved C → T, T → C, G → A, and CC → TT transitions, C → G transversion and adenine deletion, which are gene alteration types known to be related to UV radiation in the process of skin carcinogenesis in humans. Six of the thirteen tumour cases displayed the C → T transitions in the same location in exon 4 and three of the thirteen cases displayed T → C in the same location in exon 5. Conclusion The results of the present study indicate both the participation of the p53 gene and the influence of UV radiation in the formation of ASGCs in dogs.