[Cancer Cells as Dynamic System - Molecular and Phenotypic Changes During Tumor Formation, Progression and Dissemination]. / Nádorové bunky jako dynamický systém - molekulární a fenotypové zmeny v prubehu vzniku, progrese a sírení nádoru.

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.

[Multistep Process of Establishing Carcinoma Metastases]. / Vícestupnový proces vzniku vzdálených metastáz u karcinomu.

BACKGROUND: Dissemination of cancer cells from the primary tumor and establishment of therapy-resistant distant metastases is the most common cause of human cancer deaths. The primary tumor consists of a heterogeneous population of cancer cells that have to overcome activity of the immune system, insufficient delivery of nutrients and oxygen, chemotherapy, radiotherapy etc. that lead to the selection of resistant and plastic cancer cells. Another selection pressure during metastatic spread gives rise to resistant subpopulations of cells, capable of surviving and proliferating in the hostile microenvironment of distant tissues. AIM: In this article, individual steps of the metastatic cascade are described as well as the mechanisms and signaling pathways that cancer cells use to deal with them. Metastatic process is generally inefficient and only very few cells released from the primary tumor develop into metastases. This success is enabled by pro-metastatic mutations, accumulated due to the selection pressure and also by cooperation of non-transformed cells that secrete supporting factors. CONCLUSION: Recent advances in research provide deeper insights into the complex processes that lead to formation and dissemination of cancer cells. Deciphering the key points of metastatic cascade and principles of its regulation will perhaps lead to development of efficient therapeutics targeting metastatic cells.Key words: metastasis - carcinoma - vascular endothelial growth factor A - epithelial-mesenchymal transitioThis 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: 6. 5. 2016Accepted: 19. 5. 2016.

[Novel Approaches in DNA Methylation Studies - MS-HRM Analysis and Electrochemistry]. / Nové metody studia metylace DNA - MS-HRM analýza a elektrochemie.

Cytosine methylation in DNA is an epigenetic mechanism regulating gene expression and plays a vital role in cell differentiation or proliferation. Tumor cells often exhibit aberrant DNA methylation, e.g. hypermethylation of tumor suppressor gene promoters. New methods, capable of determining methylation status of specific DNA sequences, are thus being developed. Among them, MS-HRM (methylation-specific high resolution melting) and electrochemistry offer relatively inexpensive instrumentation, fast assay times and possibility of screening multiple samples/DNA regions simultaneously. MS-HRM is due to its sensitivity and simplicity an interesting alternative to already established techniques, including methylation-specific PCR or bisulfite sequencing. Electrochemistry, when combined with suitable electroactive labels and electrode surfaces, has been applied in several unique strategies for discrimination of cytosines and methylcytosines. Both techniques were successfully tested in analysis of DNA methylation within promoters of important tumor suppressor genes and could thus help in achieving more precise diagnostics and prognostics of cancer. Aberrant methylation of promoters has already been described in hundreds of genes associated with tumorigenesis and could serve as important biomarker if new methods applicable into clinical practice are sufficiently advanced.Key words: DNA methylation - 5-methylcytosine - HRM analysis - melting temperature - DNA duplex - electrochemistry - nucleic acid hybridizationThis work was supported by 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: 6. 5. 2016Accepted: 16. 5. 2016.

[Circulating Tumor DNA in Blood and Its Utilization as a Potential Biomarker for Cancer]. / Cirkulující nádorová DNA v krvi a její vyuzití jako potenciálního bio-markeru nádorových onemocnení.

Pursuing sensitive methods for detection and monitoring of oncologic diseases, that would limit the stress for patients, represents a longstanding challenge in cancer diagnostics. As an ideal noninvasive bio-markers may be considered  bio-logical molecules that can be detected in blood and that provide most relevant picture about the state and development of disease. In fact, all types of cancer cells carry somatic mutations that enable the cells to escape from regulation and to grow and progress. These mutations are only present in the DNA of tumor cells and thus are hallmarks of cancer cells. Genotyping of tumor tissues becomes a common technique in clinical oncology, but it has its limits. Tissue biopsy only yields information about a very small area of tumor at the time of extraction and in some cases it is difficult or impossible to obtain the tissue sample. Furthermore, it is an invasive method that can stress patients. Analysis of circulating tumor DNA from blood--the so-called liquid biopsy--represents one possible solution. Dying tumor cells release fragments of their DNA into the blood stream. From blood, they can be isolated and subjected to analysis using new, sensitive and precise methods that detect genomic changes. These changes are evolving over time because cancer disease is characterized by evolution and ability to select new mutations that bring growth advantages or resistance to treatment. Our inability to capture the heterogeneity during tumor development is one of the major reasons responsible for failure of cancer treatment. Recent technological progress in detection and characterization of circulating DNA could enable tumor evolution monitoring in real time and become a guideline for an accurate and prompt treatment choice.

[Programmed cell death in cancer cells]. / Programovaná bunecná smrt v nádorových bunkách.

Resistance to programmed cell death is one of the hallmarks of cancer cells that affects the process of malignant transformation as well as response to cancer therapy. The goal of this review is to summarize recent information about programmed cell death (PCD) in healthy and cancer cells, as well as new perspectives for anticancer treatments targeting these signaling pathways. Three main types of PCD are described in detail: apoptosis, necrosis/ necroptosis and cell death associated with autophagy. Among them, apoptosis plays the key role in both malignant transformation and response to therapy. In this review, we describe main signaling pathways and molecules participating in apoptosis regulation in healthy cells. In most cancer cells, mutations or aberrant expression of proteins directly or indirectly involved in induction and execution of cell death can be detected -  p53, Bcl 2 family proteins, inhibitors of apoptosis, death receptors/ ligands and other proteins. Mutations or changes in expression of these proteins and their relation to certain types of tumors are described. Finally, we provide a review of recently developed treatments that target and reactivate the machinery of programmed cell death and are currently tested in clinical trials.

[The use of flow cytometry for analysis of the mitochondrial cell death]. / Vyuzití prutokové cytometrie pro analýzu mitochondriální bunecné smrti.

Apoptosis is type I programmed cell death, a process that is essential for development and tissue homeostasis. It is a prevalent form of cell death and it proceeds via two signaling pathways - external (receptor pathway) triggered by death receptors and intrinsic (mitochondrial) apoptotic pathway with major involvement of mitochondria. Mitochondria are important cellular organelles producing energy stored in molecules of adenosine triphosphate that are essential for cell survival. The mitochondrial cell death is characterized by permeabilization of the mitochondrial outer membrane and dissipation of the transmembrane potential. Mitochondria are electronegative organelles and depolarization of the mitochondrial membrane is important for the release of proapoptotic signals. Aberrant control of the mitochondrial cell death might contribute to several diseases including cancer. Mitochondria are also a source of reactive oxygen species, Ca2+ ions and other proteins that affect processes important for the initiation and progression of tumors independently of apoptosis. Current studies focus on research of mitochondrial membrane potential and reactive oxygen species modulating various signaling pathways within the cell, their importance in carcinogenesis, and in treatment of oncological patients. Monitoring of the apoptotic markers, such as the mitochondrial membrane potential (MMP), and the level of reactive oxygen species in samples of oncological patients has a predictive value for the output of treatment protocols.