Process Of Tumor Formation Research Articles

TRPV6 Channel Is Involved in Pancreatic Ductal Adenocarcinoma Aggressiveness and Resistance to Chemotherapeutics.

Pancreatic ductal adenocarcinoma (PDAC) stands as a highly aggressive and lethal cancer, characterized by a grim prognosis and scarce treatment alternatives. Within this context, TRPV6, a calcium-permeable channel, emerges as a noteworthy candidate due to its overexpression in various cancers, capable of influencing the cell behavior in different cancer entities. Nonetheless, the exact expression pattern and functional significance of TRPV6 in the context of PDAC remains enigmatic. This study scrutinizes the expression of TRPV6 in tissue specimens obtained from 46 PDAC patients across distinct stages and grades. We manipulated TRPV6 expression (knockdown, overexpression) in the human PDAC cell lines Panc-1 and Capan-1. Subsequently, we analyzed its impact on multiple facets, encompassing Ca2+ influx, proliferation, apoptosis, migration, chemoresistance, and tumor growth, both in vitro and in vivo. Notably, the data indicate a direct correlation between TRPV6 expression levels, tumor stage, and grade, establishing a link between TRPV6 and PDAC proliferation in tissue samples. Decreasing TRPV6 expression via knockdown hampered Ca2+ influx, resulting in diminished proliferation and viability in both cell lines, and cell cycle progression in Panc-1. The knockdown simultaneously led to an increase in apoptotic rates and increased the susceptibility of cells to 5-FU and gemcitabine treatments. Moreover, it accelerated migration and promoted collective movement among Panc-1 cells. Conversely, TRPV6 overexpression yielded opposing outcomes in terms of proliferation in Panc-1 and Capan-1, and the migration of Panc-1 cells. Intriguingly, both TRPV6 knockdown and overexpression diminished the process of tumor formation in vivo. This intricate interplay suggests that PDAC aggressiveness relies on a fine-tuned TRPV6 expression, raising its profile as a putative therapeutic target.

Harnessing atomic force microscopy-based single-cell analysis to advance physical oncology.

Single-cell analysis is an emerging and promising frontier in the field of life sciences, which is expected to facilitate the exploration of fundamental laws of physiological and pathological processes. Single-cell analysis allows experimental access to cell-to-cell heterogeneity to reveal the distinctive behaviors of individual cells, offering novel opportunities to dissect the complexity of severe human diseases such as cancers. Among the single-cell analysis tools, atomic force microscopy (AFM) is a powerful and versatile one which is able to nondestructively image the fine topographies and quantitatively measure multiple mechanical properties of single living cancer cells in their native states under aqueous conditions with unprecedented spatiotemporal resolution. Over the past few decades, AFM has been widely utilized to detect the structural and mechanical behaviors of individual cancer cells during the process of tumor formation, invasion, and metastasis, yielding numerous unique insights into tumor pathogenesis from the biomechanical perspective and contributing much to the field of cancer mechanobiology. Here, the achievements of AFM-based analysis of single cancer cells to advance physical oncology are comprehensively summarized, and challenges and future perspectives are also discussed. RESEARCH HIGHLIGHTS: Achievements of AFM in characterizing the structural and mechanical behaviors of single cancer cells are summarized, and future directions are discussed. AFM is not only capable of visualizing cellular fine structures, but can also measure multiple cellular mechanical properties as well as cell-generated mechanical forces. There is still plenty of room for harnessing AFM-based single-cell analysis to advance physical oncology.

EXTH-11. TELOMERASE INHIBITION IS AN EFFECTIVE THERAPEUTIC STRATEGY IN TERT PROMOTER-MUTANT GLIOBLASTOMAS MODELS WITH LOW TUMOR BURDEN

Abstract Glioblastoma targeted therapeutics have been challenging to develop due to significant inter- and intra-tumoral heterogeneity. While many activated oncogenes in glioblastoma are subclonal, TERT promoter mutations commonly occur as clonal events and are found in up to 80% of IDH-wildtype glioblastomas. Given the high prevalence and clonal nature of TERT promoter mutations in glioblastoma, telomerase is considered a promising therapeutic target for this deadly cancer. Prior studies have validated this hypothesis, demonstrating that knockout of the transcription factor GABPA, which selectively binds to the mutant TERT promoter, as well as base editing-mediated correction of TERT promoter mutations, are selectively toxic to TERTpromoter mutant glioblastomas. However, an important limitation of this strategy is that cancer cell death does not occur immediately after telomerase ablation, but rather after several cell divisions required to reach critically short telomeres. We therefore hypothesize that telomerase inhibition would only be effective in low tumor burden glioblastomas. In this study, we used CRISPR interference to knock down TERT expression in TERT promoter-mutant glioblastoma cell lines and patient derived models. We then measured cell viability and assessed for features of telomere crisis by measuring telomere length and chromatin bridge formation. Lastly, we used a doxycycline inducible CRISPR interference system to knock down TERT expression in vivo early and late in the tumor formation process. We demonstrated that TERT promoter-mutant glioblastoma cells are sensitive to telomerase inhibition and undergo telomere crisis. In vivo, tumor formation is only inhibited when TERT knockdown is induced shortly after tumor implantation, but not when tumor burden is high. This work supports the idea that telomerase inhibition would be a suitable therapeutic strategy for glioblastoma patients with low tumor burden, for example in the adjuvant setting after surgical debulking and chemoradiation.

A Dynamic Transcriptome Map of Different Tissue Microenvironment Cells Identified During Gastric Cancer Development Using Single-Cell RNA Sequencing

Gastric cancer (GC) development trends have identified multiple processes ranging from inflammation to carcinogenesis, however, key pathogenic mechanisms remain unclear. Tissue microenvironment (TME) cells are critical for the progression of malignant tumors. Here, we generated a dynamic transcriptome map of various TME cells during multi-disease stages using single-cell sequencing analysis. We observed a set of key transition markers related to TME cell carcinogenic evolution, and delineated landmark dynamic carcinogenic trajectories of these cells. Of these, macrophages, fibroblasts, and endothelial cells exerted considerable effects toward epithelial cells, suggesting these cells may be key TME factors promoting GC occurrence and development. Our results suggest a phenotypic convergence of different TME cell types toward tumor formation processes in GC. We believe our data would pave the way for early GC detection, diagnosis, and treatment therapies.

Interleukin-34: a key molecule in the tumor microenvironment

The tumor microenvironment (TME) acquires immune resistance during the process of tumor formation. Recently, cancer immunotherapy has been attracting attention as a treatment modality, following the three major standard cancer treatments (surgical therapy, radiation therapy, and chemotherapy), for its potential to overcome such an immunosuppressive TME. Particularly, blocking antibodies against immune checkpoint molecules, such as PD-1 and CTLA-4 have caused a paradigm shift in cancer treatment. However, several patients do not respond to existing cancer immunotherapy; therefore, the establishment of a novel therapeutic target is essential. Macrophages are the most abundant cells in various tumors and are biased toward immunosuppressive forms. Therefore, research is ongoing globally to determine whether macrophages could be therapeutic targets. Interleukin-34 (IL-34) has been reported as a factor that biases macrophages to immunosuppressive forms. It is expressed in various types of cancer cells and plays important roles in multiple aspects of the TME. In this review, we comprehensively introduce the roles of IL-34 in the TME.

Continuous formation of small clusters with LGR5-positive cells contributes to tumor growth in a colorectal cancer xenograft model

AbstractNew cancer characteristics can be discovered by focusing on the process of tumor formation. Cancer stem cells (CSCs) are a key subpopulation, as they are theorized to be at the apex of the tumor hierarchy. We can better understand their function in the tumor hierarchy by using sectioned samples to observe the growth of tumors from their origins as CSCs. In this study, we evaluated the growth of moderate differentiated colorectal cancer from LGR5-positive cells, which is a CSC marker of colorectal cancer, using xenograft and three-dimensional culture models spatiotemporally. These cells express LGR5 at high levels and show CSC phenotypes. To detect them, we used a previously generated antibody that specifically targets LGR5, and were therefore able to observe LGR5-positive cells aggregating into small clusters (sCLs) over the course of tumor growth. Because these LGR5-expressing sCLs formed continuously during growth mainly in the invasive front, we concluded that the structure must contribute significantly to the expansion of CSCs and to tumor growth overall. We confirmed the formation of sCLs from gland structures using a three-dimensional culture model. In addition, sCLs exhibited upregulated genes related to stress response and partial/hybrid epithelial–mesenchymal transition (EMT), as well as genes reported to be prognosis factors. Finally, sCLs with high LGR5 expression were identified in clinical samples. Based on these results, we elucidate how sCLs are an important contributors to tumor growth and the expansion of CSCs.This study demonstrates that small clusters (sCLs) of tumor cells with high expression of LGR5 continuously form in the invasive front in a colorectal cancer xenograft model. This structure is characterized by stress response and partial/hybrid epithelial-mesenchymal transition. These sCLs are an important contributor to tumor growth and the expansion of cancer stem cells.

Attenuation correction technique for fluorescence analysis of biological tissues with significantly different optical properties.

During intraoperative fluorescence navigation to remove various neoplasms and during pharmacokinetic studies of photosensitizers in laboratory animals, in many cases, the ratio of photosensitizer accumulation in the tumor and normal tissue can reach ⩾ 10-fold, which inevitably changes their optical properties. At the same time, the tumor formation process causes various metabolic and structural changes at cellular and tissue levels, which lead to changes in optical properties. A hardware-software complex for the spectral-fluorescence studies of the content of fluorochromes in biological tissues with significantly different optical properties was developed, and it was tested on optical phantoms with various concentrations of photosensitizers, absorbers, and scatterers. To correct the influence of optical properties on the photosensitizer concentration analysis by fluorescence spectroscopy, we propose the spectrum-processing algorithm, which combines empirical and theory-based approaches.

Targeting the JAK2/STAT3 Pathway-Can We Compare It to the Two Faces of the God Janus?

Muscle cachexia is one of the most critical unmet medical needs. Identifying the molecular background of cancer-induced muscle loss revealed a promising possibility of new therapeutic targets and new drug development. In this review, we will define the signal transducer and activator of transcription 3 (STAT3) protein’s role in the tumor formation process and summarize the role of STAT3 in skeletal muscle cachexia. Finally, we will discuss a vast therapeutic potential for the STAT3-inhibiting single-agent treatment innovation that, as the desired outcome, could block tumor growth and generally prevent muscle cachexia.

Inhibition of ITGB1 enhance the anti-tumor effect of cetuximab in colorectal cancer cell.

Colorectal cancer is the second commonly seen cancer around the world and accounts for 13% of all human cancers. Among them, 25% of all case were diagnosed with metastasis and 50% occurs metastasis during the development of disease. Cetuximab is a chimeric monoclonal antibody against epidermal growth factor receptor, and is used for treatment of metastatic colorectal cancer alone or combined with chemotherapy or radiation therapy. Integrin-beta 1 (ITGB1), which is also known as CD29, and plays an important role in development of malignant cancers. However, the effect of ITGB1 in promoting the anti-tumor effect of cetuximab is not fully understand. The model of ITGB1 inhibition and overexpression was firstly constructed in LS174T cells, and the viability of cells in each group was detected using CCK-8 assay. The expression of key factors in tumor formation process at transcription level was detected using real-time quantitative polymerase chain reaction method. The expression of key proteins in metastasis process, cell apoptosis and activation of Ras/Raf/MEK signaling pathway was detected using western blotting analysis. And the concentration of key factors of in tumor formation process in cultured medium of LS174T cells were detected using enzyme-linked immunosorbent assay method. We found that cetuximab could inhibit the proliferation of LS174T cells, and inhibition of ITGB1 enhanced this effect while overexpression of ITGB1 reduced this effect. We further found that cetuximab could inhibit the expression and secretion of extracellular matrix degradation related molecules in cultured medium and transcription level. Besides, we also found that the expression of key factors in angiogenesis and extracellular matrix degradation related proteins were also reduced after cetuximab treatment. These effects might be mediated by Ras/Raf/MAPK signaling pathway and enhanced after inhibition of ITGB1 expression. Inhibition of ITGB1 might be a new therapeutic method in colorectal cancer.

On the histological structure of Kaposi’s sarcoma

Objective: to study the histological structure of various types of Kaposi’s sarcoma and the morphogenetic potentials of vascular cells in the tumor growth.Materials and methods: results of the histological examination of Kaposi’s sarcoma from 5 patients have been analyzed: biopsies of the skin and subcutaneous tissue from 3 HIV-infected patients (2 men and 1 woman) and 1 man, a participator of the liquidation (dosimetrist) of the consequences of the Chernobyl accident in 1986. The tumor nodes of the Kaposi’s sarcoma of the stomach, lymphatic mesenteric node and dura mater of a 41-year-old woman who had died aft er allogeneic kidney transplantation due to glomerulonephritis were also examined while the skin was intact. Histological preparations were stained with hematoxylin and eosin, picrofuchsin according to Van Gieson, alcian blue and impregnated with silver according to Bilshovsky.Results: it was confirmed that Kaposi’s sarcoma is the part of a multicentrally occurring viral lesion of the skin, subcutaneous tissue and internal organs caused by herpes infections of the 8th type on the background of immunosuppression. The entire process of tumor formation includes, besides the tumor growth, pre-tumor conditions (viral infection, chronic inflammation), and pre-tumor processes (intravascular neoplasia of low and high degree), which determining the diversity of the histological structure, clinical course, outcomes of neoplasms and complicates the correct diagnosis. The morphogenetic potentialities of endothelial and perithelial cells which make various variants of angiomatous structures, and also form spindle cell, myofibroblastic and fi broblastic components, are also important.Conclusions: the fifth, not yet described in the literature, variant of Kaposi’s sarcoma is highlighted - radiation, due to exposure of radiation energy.

Long noncoding RNA CCAT2 functions as a competitive endogenous RNA to regulate FOXC1 expression by sponging miR-23b-5p in lung adenocarcinoma.

Long noncoding RNA (lncRNA) may regulate the process of tumor formation. Although lncRNA CCAT2 has been identified as a key point in many diseases, its pathophysiological mechanism in lung adenocarcinoma remains unknown. We measured the expression level of CCAT2 in lung adenocarcinoma cells and normal lung epithelial cell line BEAS-2B by quantitative real-time polymerase chain reaction (qRT-PCR). As well, cell migration and proliferation were detected by transwell detection and CCK8 assay. At the same time, the new target point of CCAT2 was confirmed with bioinformatics analysis and dual-luciferase reporter assay. In addition, potential mechanisms were studied by Western blot analysis and RNA immunoprecipitation (RIP) analysis. The expression of CCAT2 was upregulated obviously in lung adenocarcinoma cells. Cell function analysis showed that upregulation of CCAT2 significantly promoted cell proliferation and migration, and reduction of CCAT2 inhibited cell migration and proliferation. In addition, CCAT2 positively regulated the expression of FOXC1 by competitive binding with miR-23b-5p. These findings indicated that CCAT2 may act as a competitive endogenous RNA (ceRNA) to regulate FOXC1 expression by competitively binding miR-23b-5p in lung adenocarcinoma.

Reconstruction of kidney renal clear cell carcinoma evolution across pathological stages

Although numerous studies on kidney renal clear cell carcinoma (KIRC) were carried out, the dynamic process of tumor formation was not clear yet. Inadequate attention was paid on the evolutionary paths among somatic mutations and their clinical implications. As the tumor initiation and evolution of KIRC were primarily associated with SNVs, we reconstructed an evolutionary process of KIRC using cross-sectional SNVs in different pathological stages. KIRC driver genes appeared early in the evolutionary tree, and the genes with moderate mutation frequency showed a pattern of stage-by-stage expansion. Although the individual gene mutations were not necessarily associated with survival outcome, the evolutionary paths such as VHL-PBRM1 and FMN2-PCLO could indicate stage-specific prognosis. Our results suggested that, besides mutation frequency, the evolutionary relationship among the mutated genes could facilitate to identify novel drivers and biomarkers for clinical utility.

Biofabrication: new approaches for tissue regeneration

The advent of Tissue Engineering (TE) in the early 1990ies was fostered by the increasing need for functional tissue and organ replacement. Classical TE was based on the combination of carrier matrices, cells and growth factors to reconstitute lost or damaged tissue and organs. Despite considerable results in vitro and in experimental settings the lack of early vascularization has hampered its translation into daily clinical practice so far. A new field of research, called "biofabrication" utilizing latest 3D printing technologies aims at hierarchically and spatially incorporating different cells, biomaterials and molecules into a matrix to alleviate a directed maturation of artificial tissue. A literature research of the relevant publications regarding biofabrication and bioprinting was performed using the PubMed data base. Relevant papers were selected and evaluated with secondary analysis of specific citations on the bioprinting techniques. 180 relevant papers containing the key words were identified and evaluated. Basic principles into the developing field of bioprinting technology could be discerned. Key elements comprise the high-throughput assembly of cells and the fabrication of complex and functional hierarchically organized tissue constructs. Five relevant technological principles for bioprinting were identified, such as stereolithography, extrusion-based printing, laser-assisted printing, inkjet-based printing and nano-bioprinting. The different technical methods of 3D printing were found to be associated with various positive but also negative effects on cells and proteins during the printing process. Research efforts in this field obviously aim towards the development of optimizing the so called bioinks and the printing technologies. This review details the evolution of the classical methods of TE in Regenerative Medicine into the evolving field of biofabrication by bioprinting. The advantages of 3D bioprinting over traditional tissue engineering techniques are based on the assembling of cells, biomaterials and biomolecules in a spatially controlled manner to reproduce native tissue macro-, micro- and nanoarchitectures, that can be utilized not only to potentially produce functional replacement tissues or organs but also to serve as new models for basic research. Mimicking the stromal microenvironment of tumor cells to study the process of tumor formation and progression, metastasis, angiogenesis and modulation of the associated processes is one of these applications under research. To this end a close collaboration of specialists from the fields of engineering, biomaterial science, cell biology and reconstructive microsurgery will be necessary to develop future strategies that can overcome current limitations of tissue generation.

Structural shift of gut microbiota during chemo-preventive effects of epigallocatechin gallate on colorectal carcinogenesis in mice.

AIMTo investigate the effect of epigallocatechin gallate (EGCG) on structural changes of gut microbiota in colorectal carcinogenesis.METHODSAn azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced colitis mouse model was established. Forty-two female FVB/N mice were randomly divided into the following three groups: group 1 (10 mice, negative control) was treated with vehicle, group 2 (16 mice, positive control) was treated with AOM plus vehicle, and group 3 (16 mice, EG) was treated with AOM plus EGCG. For aberrant crypt foci (ACF) evaluation, the colons were rapidly took out after sacrifice, rinsed with saline, opened longitudinally, laid flat on a polystyrene board, and fixed with 10% buffered formaldehyde solution before being stained with 0.2% methylene blue in saline. For tumor evaluation, the colon was macroscopically inspected and photographed, then the total number of tumors was enumerated and tumor size measured. For histological examination, the fixed tissues were paraffin-embedded and sectioned at 5 mm thickness. Microbial genomic DNA was extracted from fecal and intestinal content samples using a commercial kit. The V4 hypervariable regions of 16S rRNA were PCR-amplified with the barcoded fusion primers. Using the best hit classification option, the sequences from each sample were aligned to the RDP 16S rRNA training set to classify the taxonomic abundance in QIIME. Statistical analyses were then performed.RESULTSTreatment of mice with 1% EGCG caused a significant decrease in the mean number of ACF per mouse, when compared with the model mice treated with AOM/DSS (5.38 ± 4.24 vs 13.13 ± 3.02, P < 0.01). Compared with the positive control group, 1% EGCG treatment dependently decreased tumor load per mouse by 85% (33.96 ± 6.10 vs 2.96 ± 2.86, respectively, P < 0.01). All revealed that EGCG could inhibit colon carcinogenesis by decreasing the number of precancerous lesions as well as solid tumors, with reduced tumor load and delayed histological progression of CRC. During the cancerization, the diversity of gut microbiota increased, potential carcinogenic bacteria such as Bacteroides were enriched, and the abundance of butyrate-producing bacteria (Clostridiaceae, Ruminococcus, etc.) decreased continuously. In contrast, the structure of gut microbiota was relatively stable during the intervention of EGCG on colon carcinogenesis. Enrichment of probiotics (Bifidobacterium, Lactobacillu, etc.) might be a potential mechanism for EGCG’s effects on tumor suppression. Via bioinformatics analysis, principal coordinate analysis and cluster analysis of the tumor formation process, we found that the diversity of gut microbiota increased in the tumor model group while that in the EGCG interfered group (EG) remained relatively stable.CONCLUSIONGut microbiota imbalance might be a potential mechanism for the prevention of malignant transformation by EGCG, which is significant for diagnosis, treatment, prognosis evaluation, and prevention of colorectal cancer.

Midline Granuloma

Midline granulomaor nasal type extranodal T/NK-cell non-Hodgkin’s lymphoma often cause various problem. This tumor is a disorder of the center of the face with the characteristic of progressive destruction and ulceration, including the nose, paranasal sinuse, palate, eyes, and facial soft tissues. Etiology and pathophysiologyis unclear between inflammatory and tumor reactions. Midline granulomais included innasal granuloma disease based on biopsy examination, where as The Revised European American Lymphoma (REAL) / Wordl Health Organization (WHO) classifiesmidline granulomainextranodal T/NK-cellnon-Hodgkin’s lymphomabased on immunohistologic examination. Epstein-Barr Virus (EBV) infections 90-100% are involved in the tumor formation process. Difficult diagnosis and wide-ranging diagnosis, requiring complete anamnesis and examination, especially biopsy, imunohistology, and cytogenetics in obtaining necrosis features with vascular destruction and ulceration, inflammation with pleomorphic cell infiltrate, CD56+, CD3+, cytotoxict and EBV+ proteins. Management with radiotherapy, chemotherapy, bone marrow transplant, and immunotherapy. Complications can occur locally or systemically with spread to peripheral blood circulation, soft tissue, lung, liver, skin, gastrointestinal tract, testes, central nervous and bone marrow. Poor prognosis is less than 50%of patient who respond fully after chemotherapy and radio therapy. Pronosis can only be assessed by the International Prognostic Index (IPI).&#x0D; Midline diagnosis of granulomais difficult,management is often delayed, while its progressive nature leads to various complications, thus further aggravating the prognosis.

Abstract 808: PDGF-A overexpression and p53 depletion in rat neural precursor cells induces large brain tumors that resemble human glioblastoma

Abstract One of the major obstacles in developing new therapeutics for glioblastoma is testing these agents in reliable models that recapitulate the tumor biology of human disease. The RCAS/tv-a system enables spatial, temporal, and cell-type specific control of oncogenic transformations in the brain. In this study, we sought to develop a rat RCAS-TVA model of glioblastoma to eventually facilitate translational studies using magnetic resonance imaging (MRI), targeted radiation, focused ultrasound, and local drug delivery strategies. We developed a high copy number nestin-promoter driven tv-a (Ntv-a) transgenic Sprague-Dawley rat line. To initiate tumors, RCAS PDGF-A and p53 shRNA constructs were injected intracranially. The tumors were followed over time using MRI and MR proton spectroscopy. Animal survival was monitored and histopathology and gene expression analyses were performed. All animals (n=8) developed tumors that could be visualized with MRI throughout the tumor formation process. Early stage tumors showed relatively homogenous characteristics with minimal mass effect. Later stage tumors demonstrated large heterogeneous lesions with evidence of necrosis, increased vascularity, and significant mass effect. MR proton spectroscopy revealed increases in choline to creatinine ratio (Cho/Cr) and decreases in NAA, consistent with aggressive tumor progression. Immunohistochemistry revealed pseudopallisading necrosis, brain invasion, and vascular proliferation, all key features of human GBM. Immunohistochemistry confirmed a high proliferative index within the tumor core as well as neovascularization as evidenced by positive Ki67 and Smooth Muscle Actin (SMA) respectively. Gene expression analysis revealed approximately 1000 differentially expressed transcripts between the normal and tumor tissue. In addition to typical markers such as Ki67 and PDGFR-A overexpression, SPP1 and POSTN both of which are linked to glioma and tumor-associated macrophages, were found to be differentially expressed in the tumor. Comparisons between the rat gene expression profile and published human TCGA data indicated that the RCAS/tv-a tumors appear to align with the proneural GBM subtype. In summary, transgenic Ntv-a rats generate reproducible brain tumors following combined PDGF-A and p53 genetic alterations. The tumor progression process from low-grade tumor to high grade malignancy can be visualized with MRI. Histopathological features strongly resemble human GBM, and gene expression analysis suggests these tumors correspond to the proneural subtype. Citation Format: Nina P. Connolly, Craig S. Schneider, Amol Shetty, Su Xu, Tatsuya Ozawa, Anthony J. Kim, Jeffrey A. Winkles, Eric Holland, Graeme F. Woodworth. PDGF-A overexpression and p53 depletion in rat neural precursor cells induces large brain tumors that resemble human glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 808. doi:10.1158/1538-7445.AM2017-808

PTEN: A potential prognostic marker in virus-induced hepatocellular carcinoma.

PTEN is the second most frequently mutated tumor suppresser gene in cancers after p53. Genetic and epigenetic alterations in the PTEN gene and its regulatory regions have been reported in various studies. PTEN is a crucial downregulator of the pro-survival phosphoinositide 3-kinase/Akt/mammalian target of rapamycin pathway and also suppresses insulin signaling. Failure to regulate these pathways leads to increase in cell proliferation and migration which in turn promotes tumorigenesis. PTEN underexpression is mediated by a variety of cytokines and stress kinases which seem to collectively induce the RAS/mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) pathway. In the context of hepatocellular carcinoma, reduced expression of PTEN is seen in nearly half of the cases on average. In some cases, PTEN has been observed to be either mutated or methylated which can also lead to reduced expression or in some cases, complete loss of expression. On the cellular level, PTEN is also a target in the pathogenic pathway of hepatitis C virus core protein and hepatitis B virus X protein. These viruses appear to alter PTEN regulation and pro-apoptotic ability to enhance the process of tumor formation. In perspective of the crucial role PTEN plays in balancing proliferation and apoptosis, we propose PTEN as a valuable marker in the diagnosis, assessment of tumor grade, and disease stage in hepatocellular carcinoma patients.

Cancer Cells as Dynamic System – Molecular and Phenotypic Changes During Tumor Formation, Progression and Dissemination

Dynamic, punctual and perfectly coordinated cellular response to internal and external stimuli is a crucial prerequisite for adaptation of mammalian cells to all changes that occur during cellular development under physiological conditions. Hijacking this ability is characteristic for tumor cells that are capable to adapt to unfavorable conditions which contribute to the formation and development of cancer during the process of tumor formation and progression. By changing key mechanisms, malignant cells can avoid cell death and thus allow development and spread of the tumor. The changes at the genetic level are manifested by various phenotypic characteristics, through which tumor cells are able to escape defense mechanisms, to acquire resistance to treatment, to invade and to create secondary tumors. In recent years, one of the most studied properties include changes in energy metabolism, when tumor cells specifically control reprogramming of the main metabolic pathways for their own benefit and to satisfy their increased needs not only for energy, but also for building materials required for increased proliferation. To adapt to extracellular conditions, it is necessary that cells undergo morphological changes, where modifications in the cell shape through reorganization of cytoskeletal filaments allow tumor cells to increase their invasiveness and other aggressive features. Clarifying these changes together with understanding of the switch in the genetic program within cancer cells, which allows them to overcome different stages of differentiation from cancer stem cells to fully differentiated cells, would be an important prerequisite for identification of the cancer cell "weaknesses" and may lead to improved cancer treatment. The ability of tumor cells to alter the rules of their own organism thus represents an important challenge for oncological research.Key words: cellular reprogramming - cancer cell plasticity - cancer metabolism - tumor heterogeneity - cytoskeleton remodeling - metastasis - oncogenesisThis work was supported by the project MEYS - NPS I - LO1413.The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study.The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 3. 7. 2016Accepted: 11. 8. 2016.

Runx1: a new driver in neurofibromagenesis.

The Runt-related transcription factor-1 (RUNX1 or AML1) encodes a transcription factor that serves as a master developmental regulator. It is important for hematopoiesis, angiogenesis, maturation of megakaryocytes, and differentiation of T and B cells [1]. Runx1 is also important for neuronal development and glial cell differentiation [2]. Runx1 is integrated into a complex regulatory network which acts both at the transcriptional and post-transcriptional levels. Runx1 activity can be regulated by several posttranslational modifications, including phosphorylation, de-phosphorylation, SUMOylation, acetylation, methylation and ubiquitination. These modifications control various aspects of transcriptional factors' activities such as auto inhibition, dimerization and ubiquitin-mediated degradation [3]. Besides its developmental determination role, RUNX1 is involved in malignant tumor formation. Reports have shown that RUNX1 is frequently de-regulated and has paradoxical effects in human cancers, in which it can function either as a tumor suppressor or oncogene [3, 4]. RUNX1 has been implicated as a tumor suppressor in several solid tumors including breast cancer, esophageal adenocarcinoma, colon cancer and possibly prostate cancer but acts as an oncogene in head/neck squamous cell carcinomas, endometrial cancer, and epithelial cancer [3, 4]. Because Runx1 is a sequence specific DNA-binding transcription factor, whether it functions as oncogene or tumor suppressor is dependent on its interaction with specific co-regulatory proteins. We recently showed that RUNX1 acts as an oncogene in the context of loss of neurofibromatosis type 1 (Nf1). Instead of chromosomal translocation and mutation frequently detected in other cancers, Runx1 is overexpressed in human and mouse neurofibroma-initiating cells, both at the messenger RNA and protein levels. Specifically, loss of Nf1 increases number of embryonic day 12.5 Runx1+/Blbp+ Schwann cell progenitors that enable neurofibroma formation in a mouse model (Figure ​(Figure1).1). Targeted genetic deletion of RUNX1 in Schwann cells and Schwann cell progenitors delays mouse neurofibroma formation in vivo (5). Figure 1 Model of neurofibromagenesis It is not clear how loss of Nf1 induces Runx1 overexpression and serves as an oncogene. There are several potential possibilities: 1) NF1 is known to encode a Ras-GTPase activating protein (Ras-GAP) and the Ras-MEK-ERK pathway is important for Nf1 neurofibroma formation [6]. Runx1 may be phosphorylated by the elevated MEK signaling to initiate the tumor formation process. 2) Elevated Wnt or Notch signaling can directly or indirectly activate Runx1, which can accelerate G1-S transition and stimulates cell proliferation. Consistently, our results show that loss of Runx1 in Schwann cells decreased cell proliferation by activating Trp53-p21 or increased cell apoptosis by inhibiting anti-apoptotic gene Bcl-2 in the context of Nf1−/− Schwann cell environment. It is possible that the elevated Runx1 within the neurofibroma cell alters cell fate (i.e. proliferation or differentiation) through Trp53-p21. Further experiments are needed to determine how p21 and Trp53 were activated or Bcl-2 was inactivated in the Runx1fl/fl;Nf1fl/fl; Dhhre tumors. 3) Runx1 might interact with epigenetic regulators such as the chromatin remodeling complexes, SWI/SNF, or polycomb repressive complexes to affect Runx1 activity by post-translational modification [7]. Overall, our study supports an oncogenic role of Runx1 in neurofibroma initiation and/or maintenance, but the underlying mechanism(s) are not clear. With increasing knowledge of RUNX1 biology, targeting the transcription factor RUNX1 or RUNX1 pathway might provide a novel therapy for neurofibroma as well as other tumors which overexpress RUNX1.

A75: Modern concepts of cellular and molecular mechanisms of breast cancer and their prognostic significance

Breast cancer is one of the most common cancers in women. The incidence of breast cancer in 2014 in the Republic of Mordovia was 69.9 per 100,000 female populations. Breast cancer occurs when excessive expression of oncoproteins switches in the case of transformation of proto-oncogene in PRADI. In primary breast tumors, mutations and the expression of the three oncogenes Her2/neu, C-mys, Int-2, as well as in supressonyh genes – the p53 gene and the retinoblastoma gene RB are the most common. Several studies found that oncogene – C-mys was expressed in 16.8% of primary breast cancer cases and in 35% cases with subsequent development of metastases. Proteins that stimulate the phosphorylation of mitogen-activated protein kinasescan activateunder the influence of growth factors. Development of breast cancer is regulated by a complex interaction of many hormones and growth factors. Currently, one of the leading theories of developing breast cancer is the increased hormonal stimulation of proliferative processes in the development of neoplasia. One of the manifestations of hormonal imbalance in tumor during a regular decrease in blood competitive inhibitor of the biological effects of estrogen – progesterone, which is in correlation with the stage of the spread of neoplasia. The role of the overproduction of estrogen in the pathogenesis of breast cancer is confirmed by the fact that in women who underwent oophorectomy before the age of 38 years, the risk of breast cancer development is 1.5 times less than in those who did not have such operation. Excessive accumulation of lipid peroxidation products in the area of neoplasia activates mechanisms violation of intercellular interaction that caused the destruction of the lipid components of membranes. The study group included 112 patients treated at the State Institution of Health of the Republic of Mordovia “National Oncology Center”. To identify the nature of tumors, all patients underwent immunohistochemical analysis. Androgen receptors were found in 48% of breast cancer cases, the expression level of androgen receptor in the tumor was much lower than the expression level of estrogen and progesterone receptors. Low levels of progesterone receptor expression in breast cancer cells were combined with high levels of expression of Ki-67 antigen, HER-2 oncoprotein in tumor cells. Patients with HER-2 (3+) and (2+) had more frequent multiple metastases in lymph nodes compared to patients with HER-2 (0) and (1+) phenotypes. Maximum expression of HER-2 oncoprotein in tumor cells indicated high metastatic potential and poor prognosis. It may be concluded that the cellular and molecular mechanisms of breast cancer are complex. Therefore, carcinogenesis has a “multistep” nature and at least two or more mutations in the cells of the same clone – parent and child are required to generate malignant tumors. Thus, the development of oncogenic transformation does not necessarily mean the process of tumor formation.