Activation of IGF/IGF-IR signaling pathway fails to induce epithelial-mesenchymal transition in pancreatic cancer cells.

BACKGROUND: Pancreatic cancer stromal cells produce various protein factors, which presumably provide cancer cells with drug resistance and may influence their ability to form metastasis via induction of epithelial-mesenchymal transition (ЕМТ). The goal of our project was to study the effects of IGF-I on expression of protein markers of epithelial and mesenchymal differentiation, and on expression of transcriptional regulators of EMT in pancreatic cancer cell lines. METHODS: We used Western blot analysis to study the expression patterns of epithelial and mesenchymal protein markers in pancreatic cancer cell lines, which have been stimulated with IGF-I for various periods of time. The ELISA technique was employed to determine the concentration of IGF-I in conditioned media. Additionally, the effect of IGF-I on proliferation of pancreatic cancer cells was measured via MTS technique. RESULTS: We investigated the effect of IGF/IGF-IR signaling pathway activation on expression levels of cell differentiation markers in five pancreatic cancer cell lines (AsPC-1, BxPC-3, Capan-2, MiaPaCa-2 and Panc1). The IGF-I stimulation led to phosphorylation of IGF-IR and activation of PI-3K/Akt signaling cascade. At the same time our results reveal that the activation of IGF/IGF-IR signaling pathway in pancreatic cancer cells does not induce a significant shift in cell phenotype towards mesenchymal differentiation and does not induce a decrease in expression levels of epithelial protein markers. CONCLUSIONS: Our results demonstrate that IGF-I does not function as an effective inductor of EMT in pancreatic cancer cell lines and that stimulation of IGF-I/IGF-IR signaling pathway does not lead to EMT associated changes in cell differentiation.

Expression of the FAP gene in non-fibroblast human cell lines. Development of cancer-associated fibroblast models.

The fibroblast activation protein (FAP) is selectively expressed in cancer-associated fibroblasts (CAFs) and facilitates tumor progression, which makes this protein an attractive therapeutic target. There are difficulties in obtaining CAFs for studying the function and suppression of FAP. In this work, the expression level of FAP was determined by PCR assay in 25 human cell lines and 8 surgical samples of tumor stroma. The expression of FAP was observed in all tumor stroma samples and in four cell lines: NGP-127, SJCRH30, SJSA-1, and A375. The level of FAP expression in NGP-127, SJCRH30, and SJSA-1 lines as well as in CAFs of patients was comparable, which makes these cell lines a possible model for studying FAP.

Expression of Therapeutic Gene FCU1 Sensitizes Pancreatic Cancer Cells to 5-Fluorocytosine and Enhances the Cytotoxic Effect of 5-Fluorouracil.

Hybrid therapeutic gene FCU1 gene was cloned into a lentiviral expression vector and the therapeutic effect of its expression was studied in three pancreatic cancer cell lines. Expression of FCU1 gene sensitized cells of two of three studied pancreatic cancer cell lines to 5-fluorocytosine. In addition, uracil phosphoribosyl transferase activity of the hybrid FCU1 protein increased sensitivity of transfected cells of all three studied pancreatic cancer cell lines to 5-fluorouracil, a standard chemotherapeutic agent.

Downregulation of expression of mater genes SOX9, FOXA2, and GATA4 in pancreatic cancer cells stimulated with TGFß1 epithelial-mesenchymal transition.

We show characteristic morphological changes corresponding to epithelial-mesenchymal transition (EMT) program fulfillment in PANC1 cell line stimulated with TGFß1. Our results support downregulation of E-cadherin protein. We show 5- and 28-fold increase in SNAI1 and SNAI2 expression levels and 25- and 15-fold decrease in CDH1 and KRT8 expression levels, respectively, which confirms the EMT-program fulfillment. We demonstrate downregulation of expression of pancreatic master genes SOX9, FOXA2, and GATA4 (2-, 5-, and 4-fold, respectively) and absence of significant changes in HES1, NR5A2, and GATA6 expression levels in the cells stimulated with TGFß1. Our results indicate the absence of induction of expression of PTF1A, PDX1, HNF1b, NEUROG3, RPBJL, NKX6.1, and ONECUT1 genes, which are inactive in PANC1 cell line after the EMT stimulated by TGFß1.

[SNAI1 and SNAI2 - transcriptional master-regulators of epithelial-mesenchimal transition].

Epithelial-mesenchymal transition is a result of cellular epigenetic reprogramming. During this process differentiated epithelial cells lose specific markers of epithelial phenotype and gradually start displaying qualities of poorly differentiated mesenchymal cells, resistant to apoptosis and capable of local invasion. Despite their obvious importance for biology and medicine, many aspects of epithelial-mesenchymal transition, especially those related to its genetic regulation, remain poorly characterized. In this review we analyze molecular structure and mechanisms of regulation of two closely-related transcription factors SNAI1 and SNAI2, which play an important role in induction and progression of epithelial-mesenchymal transition during both normal development and carcinogenesis. Special attention is paid to the role of SNAI1 and SNAI2 and their active co-reeressors in initiation of epigenetic repression of epithelial differentiation marker genes.

[SAYP--a novel regulator of metazoan development].

SAYP is a dual-function transcriptional coactivator of RNA polymerase II. It is a metazoan-specific factor involved in different signaling pathways that control normal development. In Drosophila, SAYP is present in the organism from the early stages of development and participates in cell cycle synchronization at the blastoderm stage. SAYP is abundant in many embryonic cells and in imaginal discs of larvae and is crucial for oogenesis in adults. At the molecular level, SAYP serves as a basis for assembling the BTFly nuclear supercomplex consising of the Brahma and TFIID coactivators. We suppose that BTFly and other similar nuclear supercomplexes play an important role in ontogenesis.

Cellular and molecular phenotypes of proliferating stromal cells from human carcinomas.

BACKGROUND: Stromal cells are a functionally important component of human carcinomas. The aim of this study was to obtain and characterise primary cultures of stromal cells from human carcinomas and the corresponding surrounding normal tissue. METHODS: Primary stromal cell cultures from tumours of lung, oesophagus and pancreas were obtained using a mild tissue dissociation method and a medium for culturing mesenchymal cells. Immunofluorescence staining and western blotting were used to analyse the expression of differentiation markers and selected known oncoproteins in the cell cultures obtained. RESULTS: A panel of stromal primary cultures was prepared from different human tumours and from matched normal cancer-free tissues. The in vitro proliferative potential of tumour-associated fibroblasts was shown to be higher than that of matched normal stromal cells. A mutational analysis of the TP53 and KRAS2 genes in a number of stromal cultures did not reveal known mutations in most cells of the cultures studied. Western blot analysis showed that stromal cells of lung tumours were characterised by a statistically significantly lower expression level of the p16 protein as compared with that in normal lung stromal cells. An important finding of our study was that, according to immunofluorescence assay, a fraction of fibroblast-like vimentin-positive cells in some tumour and normal stromal cell cultures expressed an epithelial marker - cytokeratins. CONCLUSIONS: Proliferating stromal cells from the carcinomas studied proved to be genetically normal cells with altered expression profiles of some genes involved in carcinogenesis, as compared with normal stromal cells. Epithelial-mesenchymal transition may lead to the emergence of transdifferentiated fibroblast-like cells in tumour stroma and in the tumour-surrounding tissue.

[Functions of transcription factor TRF2 in Drosophila melanogaster].

A study was made of the function of the Drosophila melanogaster TRF2 protein. Expression analysis of the trf2(P1) mutation implicated TRF2 in the D. melanogaster embryo development. High-level expression of the trf2 gene was observed in female germline cells. A high level of TRF2 was detected in primary spermatocytes and trophocytes, characterized by intense transcription. In the female gonads, TRF2 was detected in both nurse cells with intense transcription and transcriptionally inactive oocyte nuclei. In addition, TRF2 proved to be necessary for premeiotic chromatin condensation and further differentiation of germline cells.

A relatively small 5' regulatory region of esterase S gene of Drosophila virilis determines the specific expression as revealed in transgenic experiments.

Expression of the esterase S gene of Drosophila virilis was studied in transgenic experiments. Truncated genomic copy of this gene including 400 bp of 5' regulatory region was integrated into the genome of Drosophila melanogaster. The products of the transferred gene were detected. It was found that strict temporal and tissue specificity of the esterase S gene expression is conserved in transformed flies. The results suggest that this specificity is evidently determined by the regulatory region of the esterase S gene and controlled by cis mechanism.

The expression of esterase S gene of Drosophila virilis in Drosophila melanogaster.

Drosophila melanogaster was transformed with the esterase S gene from Drosophila virilis. This gene is strongly activated in ejaculatory bulbs of mature males of Drosophila virilis. The closely related gene from Drosophila melanogaster is activated in ejaculatory ducts. The tissue- and stage-specific expression of incomplete genomic copy of the esterase S gene integrated into the Drosophila melanogaster genome is the same as in Drosophila virilis. These data show that tissue and stage specificity is determined by relatively small 5' regulatory region of the esterase S gene. The comparison between deduced amino-acid sequences of the esterase S of Drosophila virilis and esterase 6 of Drosophila melanogaster was performed. These sequences revealed 50% homology.

Genetic control and expression of the major ejaculatory bulb protein (PEB-me) in Drosophila melanogaster.

PEB-me is a predominant protein of mature Drosophila melanogaster ejaculatory bulbs. It is resolved into four or five closely spaced subfractions (apparent molecular weight 35-39 kD) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Four electrophoretic variants of PEB-me differing in apparent molecular weight by 200-800 daltons were found. These appear to be controlled by four alleles of a gene (peb) located by recombination and deletion mapping to the 60F1-2 region of chromosome 2. A minor ejaculatory bulb protein of ca. 80 kD (hPEB) was found to be immunochemically related to PEB and possibly encoded by peb. PEB is not detected by immunoblotting techniques in virgin females, in male tissues other than the ejaculatory bulb, or during developmental stages preceding the formation of this organ. The results of transplantations of genital imaginal discs and of immature ejaculatory bulbs between two strains having different PEB alleles suggest that the ejaculatory bulb is the site of PEB synthesis. In flies mutant for tra, tra-2, dsx, or ix, tissue specificity of PEB localization is retained and the protein is found whenever the ejaculatory bulb is formed, regardless of the chromosomal sex of the fly. The protein is transferred into the female genital duct during mating, where it can be detected for up to 12 hr. Possible functions of PEB in Drosophila reproduction are discussed.

[The proteins of the ejaculatory bulbs in different species of Drosophila]. / Belki semiavynosiashchikh lukovits razlichnykh vidov Drosophila.

A comparative electrophoretic study or ejaculatory bulb proteins in 29 different Drosophila species has been carried out. In all analyzed species, ejaculatory bulb contains a major component (designated as PEB). It has molecular mass of 61-65 kDa in the species of virilis group, 33-36 kDa in species of obscura group, and 34-56 kDa in species of melanogaster group. Using immunoblotting technique, we have demonstrated that PEB is introduced into organs of female sex tract during mating. The nature and significance of revealed interspecific differences in PEB proteins has been discussed.

[The protein of the ejaculatory bulb (PEB) in Drosophila melanogaster. 1. Its stage specificity and sex dimorphism]. / Belok semiavynosiashchei lukovitsy (PEB) u Drosophila melanogaster. 1. Stadiespetsifichnost' i polovoi dimorfizm.

PEB is the major protein (35-39 kDa) of highly differentiated ejaculatory bulbs in D. melanogaster. A minor ejaculatory bulb protein (hPEB) of about 80 kDa was detected using immunoblotting technique. Both proteins exhibit parallel genetic variation in electrophoretic mobility. This suggests that they are coded by the same gene. The proteins are present in adult males and are not detected in virgin females. During development they are first detected in male pupa at the stage of eye pigmentation (that is shortly before imago eclosion). The quantities of PEB and hPEB increase and reach the constant level at 6-10 day of imago development.