The mRNA content of the transcription factors KLF5 and ZEB1 was studied in pancreatic tumor tissues and in fetal and normal pancreas. Transcription of these factors was not high and similar in normal and fetal pancreatic tissues but greatly increased in the pancreatic ductal adenocarcinoma tissues. A significant positive correlation between the KLF5 and ZEB1 transcription levels in the pancreatic tumor tissues was observed.

The article is an attempt to provide an overview of the relationships between the regulatory genetic mechanisms of three fundamental processes of biology, i.e., development, evolution, and cancer. The problems of the evolutionary inevitability of the onset of cancer, the evolutionarily developed systems for protecting the body against tumors, and the general systems of regulation used in evolution, development, and cancer are considered.

Multifunctional activity of the PDX1 gene product is reviewed. The PDX1 protein is unique in that being expressed exclusively in the pancreas it exhibits various functional activities in this organ both during embryonic development and during induction and progression of pancreatic cancer. Hence, PDX1 belongs to the family of master regulators with multiple and often antagonistic functions.

Exogenous expression of the gene encoding the pancreatic master regulator PDX1 in cell lines with different degrees of differentiation of pancreatic cancer cells is accompanied by changes in the expression of known master genes involved in cancer progression. In BxPC3PDX+ cells, as compared to BxPC3PDX–, we detected an increased expression of the following genes: NKX6.1 (2 times), NR5A2 (2.5 times), KLF5 (1.8 times), ZEB1 (3 times), and ONECUT1 (1.3 times), as well as a decreased expression of MUC1 and SLUG genes (3 and 2 times, respectively). In PANC1PDX+ cells, as compared to the control PANC1PDX– cells, we detected a decreased expression of ISL1 (2 times) and an increased expressed of KRT8 (2 times) and MUC1 (by 30%). In the high-grade cell lines (including the BxPC3 line studied), the total content of sites containing the marks of active enhancers was higher than that in the low-grade cell lines (PANC1).

Great successes in identification and deciphering of mechanisms of the adult stem cells regulation have given rise to the idea that stem cells can also function in tumors as central elements of their development, starting from the initial stage and continuing until metastasis. Such cells were called cancer stem cells (CSCs). Over the course of intense discussion, the CSCs hypothesis gradually began to be perceived as an obvious fact. Recently, the existence of CSCs has been indeed confirmed in a number of works. However, when are CSCs universal prerequisites of tumors and to what extent their role is essential for tumor evolution remains an issue far from resolved. Likewise, the problem of potential use of CSCs as therapeutic targets remains unsolved. The present review attempts to analyze the issue of cancer stem cells and the potential of targeting them in tumor therapy.

Pioneer transcription factors constitute a heterogeneous group of regulatory animal proteins that, unlike other transcription factors, are able to recognize and bind target DNA sequences within condensed chromatin. This binding can alter the local chromatin structure and facilitate the binding of other proteins, thus contributing to subsequent events required for gene regulation. The ability to bind to the silent genes in a closed environment makes pioneer factors an extremely important tool in such processes, which that are accompanied by fundamental restructuring of the cell phenotype as differentiation during embryonic development and cell reprogramming. These proteins are able to remain bound to the target sequences during mitotic division and are likely to participate in the maintenance of cellular memory. Pioneer factors are likely to take an active part in the processes of carcinogenesis and maintaining the tumor cell phenotype, but their role in these processes requires additional examination. It is reasonable to suppose that further study of transcription factors of this group will make it possible to better understand the genetic processes in embryonic development, to improve the efficiency of cell reprogramming, as well as to develop new approaches to cancer diagnostics and therapy.

Recent data on adult stem cells are reviewed. According to the present dominant paradigm, it is most probable that cancer predisposition arises or cancer is initiated in these cells.

The present review is an attempt to summarize the recent data on adult stem cells which, according to the present dominant paradigm, most probably can be predisposed to cancer development, or in which cancer is initiated.

The transformation of normal precursors into cancer cells is an intricately regulated, multistep process. The master regulatory genes that play a crucial role in the process of organism development may also play a key role in carcinogenesis. From such a point of view, cancer is not simply a genetic disease that is due to a progressive accumulation of mutation—it is also a disorder of the developmental system of the tissue in which cancer emerges. Master regulators and their genes disturb stem cell differentiation upon mutation and thus may serve as targets for cancer therapy, in addition to the classic oncogenes and suppressors of tumor formation. This review is an attempt to give a modern concept of master genes and their functions in adult stem cells of the organism and in carcinogenesis, with pancreatic cancer as an example.

Development of targeted drug delivery system is key problem of cancer gene therapy. To ensure specific delivery of these therapeutic compounds to the tumor it is preferable for therapeutic gene expression to occur predominantly in cancer cells. Therefore, when testing drug in vivo, it is necessary to study distribution of therapeutic gene expression products in different tissues of the organism. Sodium iodide symporter (NIS) is attractive reporter because its tissue level is easily quantitatively detected by noninvasive imaging methods. Different promoters are used to direct expression of therapeutic genes in tumor cells: strong nonspecific, moderate tissue-specific and tumor-specific. Tumor-specific promoters function in wide range of tumor cells, however they are relatively weak. Relationship between promoter and sodium iodide symporter activity is unclear to date. In this report we examined activity of different promoters in two melanoma cell lines, functional activity of NIS driven by these promoters, also we compared promoter strength and NIS activity. We demonstrated that in spite of strong differences in promoter activity functional activity of NIS directed by these promoters varies weakly. Relatively weak melanoma-specific promoter directs high NIS activity in melanoma cell, however weaker cancer-specific promoters drive high NIS activity only in certain melanoma cell line.

Разработка систем направленной доставки лекарственных средств особенно актуальна для создания генно-терапевтических препаратов, направленных на узнавание и уничтожение опухоли. При адресной доставке таких препаратов в опухоль желательно, чтобы терапевтические гены экспрессировались преимущественно в раковых клетках. Поэтому при проведении испытаний in vivo необходимо изучать распределение продуктов экспрессии терапевтических генов в различных тканях организма. Натрий-йодидный симпортер считается привлекательным репортером, так как его содержание в тканях можно количественно определять неинвазивными методами. Терапевтические гены экспрессируют в опухолевых клетках с использованием промоторов различного типа: сильных неспецифических, умеренно активных тканеспецифических и опухолеспецифичных, которые работают в широком спектре опухолевых клеток, но обладают невысокой активностью. Связь между активностью промотора и натрий-йодидного симпортера, используемого в качестве репортерного, до сих пор неясна. В представленной работе с помощью репортерного гена изучена активность промоторов трех типов в клетках меланомного происхождения. Определен также уровень функциональной активности натрий-йодидного симпортера, продукта экспрессии клонированного гена NIS, под контролем выбранных промоторов, проведено сравнение этих активностей. Нами показано, что несмотря на большие различия в активности промоторов, функциональная активность натрий-йодидного симпортера, образующегося при использовании этих промоторов, изменяется слабо. Так, использование сравнительно слабого, но меланомоспецифичного промотора обеспечивает высокий уровень активности натрий-йодидного симпортера в клетках меланомы. При этом более слабые опухолеспецифичные промоторы определяют высокий уровень активности натрий-йодидного симпортера только в некоторых клетках меланомного происхождения.

Targeted drug delivery systems are special importance for developing gene therapeutic drugs that recognize and eliminate tumor cells. It is desirable that therapeutic genes be expressed predominantly in tumor cells after their targeted delivery into the tumor. Hence, the distribution of the expression product through various tissues should be studied when testing a therapeutic gene in vivo. The sodium iodide symporter (NIS) is attractive as a reporter because its tissue level is easy to quantify by noninvasive imaging methods. Therapeutic gene expression in tumor cells is achieved using various promoters, including strong nonspecific promoters; moderately active tissue-specific promoters; and tumor-specific promoters, which function in a broad range of tumor cells, but have low activity. The relationship between the promoter strength and reporter NIS activity is still unclear. The reporter gene was used to test three promoters types for activity in melanoma cells. The functional activity of NIS expressed from a cloned gene was compared for the three promoters types. Although the promoters greatly varied in strength, only minor changes were observed for NIS functional activity. A relatively weak melanoma-specific promoter ensured a high NIS activity in melanoma cells. Weaker tumorspecific promoters determined a high NIS activity only in some cells of the melanoma origin.

A method for the in vitro evaluation of the toxic effects occurring in human cell lines upon the expression of genes from a range of pathogens is proposed. The method is based on the transient expression of the genes in the HEK293 cell line. Induction of cell death upon the expression of the gene coding for protease 3C from the human hepatitis A virus has been demonstrated for the first time using the method proposed. Expression of the gene coding for protease 2A from human poliovirus has also been shown to induce cell death, while cathepsins B and D did not have a cytotoxic effect on the culture used.

In biotechnology, simultaneous expression of more than one target gene is often required. Multicistronic vectors encoding several proteins are being actively developed for this purpose. Most often, the commercially available vectors utilize various types of internal ribosomal entry site of the encephalomyocarditis virus ( IRES EMCV ). However, many researchers consider bicistronic vectors on the basis of sequences that encode self-cleaving 2A peptides more promising. In the work, we compare the efficiency of gene expression in cells transfected with bicistronic constructs bearing either IRES EMCV or the P2A nucleotide sequence corresponding to the porcine teschovirus-1 2A peptide. Efficiency of gene expression was determined in three mammalian cell lines by measurement of co-expression levels of genes coding for RFP and EGFP proteins linked by IRES or P2A sequence. A higher level of the transgene expression was detected in cells transfected with P2A sequence-based genetic constructs.