Potential of modern circulating cell-free DNA diagnostic tools for detection of specific tumour cells in clinical practice

Personalized medicine is a developing field of medicine that has gained in importance in recent decades. New diagnostic tests based on the analysis of circulating cell-free DNA (cfDNA) were developed as a tool of diagnosing different cancer types. By detecting the subpopulation of mutated DNA from cancer cells, it is possible to detect the presence of a specific tumour in early stages of the disease. Mutation analysis is performed by quantitative polymerase chain reaction (qPCR) or the next generation sequencing (NGS), however, cfDNA protocols need to be modified carefully in preanalytical, analytical, and postanalytical stages. To further improve treatment of cancer the Food and Drug Administration approved more than 20 companion diagnostic tests that combine cancer drugs with highly efficient genetic diagnostic tools. Tools detect mutations in the DNA originating from cancer cells directly through the subpopulation of cfDNA, the circular tumour DNA (ctDNA) analysis or with visualization of cells through intracellular DNA probes. A large number of ctDNA tests in clinical studies demonstrate the importance of new findings in the field of cancer diagnosis. We describe the innovations in personalized medicine: techniques for detecting ctDNA and genomic DNA (gDNA) mutations approved Food and Drug Administration companion genetic diagnostics, candidate genes for assembling the cancer NGS panels, and a brief mention of the multitude of cfDNA currently in clinical trials. Additionally, an overview of the development steps of the diagnostic tools will refresh and expand the knowledge of clinics and geneticists for research opportunities beyond the development phases

THE ROLE OF BRAIN-DERIVED NEUROTROPHIC FACTOR IN THE PATHOPHYSIOLOGY OF SUICIDAL BEHAVIOR

Suicidal behaviour is a major public health concern. It is known that the pathogenesis of suicidal behaviour involves altered neural plasticity, resulting in the aberrant stress response of the central nervous system to environmental factors. Indeed, altered brain structure and function was found in suicide victims. Neurotrophins are growth factors that are involved in the regulation of structural, synaptic, and morphological plasticity and in the modulation of the strength and number of synaptic connections and neurotransmission. Brain-derived neurotrophic factor (BDNF) the most studied and the most widely distributed among neurotrophins binds to a tropomyosin-related kinase B (TrkB) receptor and to a pan75 neurotrophins receptor. It has been reported that BDNF production is decreased in all patients with suicidal behaviour and in all suicide victims regardless of a psychiatric diagnosis. It was also found that the mRNA and protein level of BDNF was significantly lower in both the prefrontal cortex and the hippocampus of suicide subjects. Different mechanisms could be involved in the regulation of BDNF gene expression, among which epigenetic mechanisms seem to play a key role. However, also for a functional polymorphism (rs6265) Val66Metit has been shown that the Met allele is associated with the reduced BDNF activity. Further, a recent meta-analysis including 12 studies showed a trend for the Met-carrying genotypes and Met allele conferring risk for suicide. Among included studies, our study with the largest sample size, indicated that the combined Met/Met and Met/Val genotypes of the BDNF Val66Met variant could be the risk factor for violent suicide in female subjects and for suicide in victims exposed to childhood trauma. In accordance with previous reports, our findings demonstrate that aberrant regulation of BDNF synthesis is associated with suicidal behaviour

TRYPTOPHAN HYDROXYLASE 2 (TPH 2) SINGLE NUCLEOTIDE POLYMORPHISMS, SUICIDE, AND ALCOHOL-RELATED SUICIDE

Background: Suicide has been identified as a serious public health problem that is often accompanied by alcohol misuse and dependence. It seems that suicide is a result of an interplay between distal (e.g. genetic loading, family history of suicide) and proximal factors (e.g. existence of psychiatric disorder, events conferring acute stress), as well as their interactions. However, like suicide, alcohol dependence seems to be a multifactorial disorder caused by genetic and environmental factors. Serotonergic dysfunction has been implicated to be involved in the pathophysiology of substance abuse, and has also an important role in suicidal behaviour. Studies investigating suicide, alcohol-related suicide and the rate limiting enzyme of serotonin synthesis, tryptophan hydroxylase 2 (TPH2), remain to date rather limited. Results: Recent studies of TPH2 showed a range of strong, mild or no association with suicide and alcohol-related suicide, depending on a study group and genetic variants tested. Overall, to date the clinical effects seems to be quite modest. Among suicide victims with more impulsive and verbal aggressive behaviour more alcohol misuse or dependency was present. Conclusions: Suicide and alcoholism are often comorbid disorders with a complex nature. They are both strongly linked to serotonin modulation, and therefore association studies of SNPs in genes from the serotonergic system could provide an insight into the genetic background of such disorders. However, based on current results we cannot draw any conclusions, but further research to clarify the interplay between serotonergic system dysfunction, suicide, alcohol dependence, impulsivity and the role of TPH2 enzyme is needed

THE ROLE OF BRAIN-DERIVED NEUROTROPHIC FACTOR IN THE PATHOPHYSIOLOGY OF SUICIDAL BEHAVIOR

Suicidal behaviour is a major public health concern. It is known that the pathogenesis of suicidal behaviour involves altered neural plasticity, resulting in the aberrant stress response of the central nervous system to environmental factors. Indeed, altered brain structure and function was found in suicide victims. Neurotrophins are growth factors that are involved in the regulation of structural, synaptic, and morphological plasticity and in the modulation of the strength and number of synaptic connections and neurotransmission. Brain-derived neurotrophic factor (BDNF) the most studied and the most widely distributed among neurotrophins binds to a tropomyosin-related kinase B (TrkB) receptor and to a pan75 neurotrophins receptor. It has been reported that BDNF production is decreased in all patients with suicidal behaviour and in all suicide victims regardless of a psychiatric diagnosis. It was also found that the mRNA and protein level of BDNF was significantly lower in both the prefrontal cortex and the hippocampus of suicide subjects. Different mechanisms could be involved in the regulation of BDNF gene expression, among which epigenetic mechanisms seem to play a key role. However, also for a functional polymorphism (rs6265) Val66Metit has been shown that the Met allele is associated with the reduced BDNF activity. Further, a recent meta-analysis including 12 studies showed a trend for the Met-carrying genotypes and Met allele conferring risk for suicide. Among included studies, our study with the largest sample size, indicated that the combined Met/Met and Met/Val genotypes of the BDNF Val66Met variant could be the risk factor for violent suicide in female subjects and for suicide in victims exposed to childhood trauma. In accordance with previous reports, our findings demonstrate that aberrant regulation of BDNF synthesis is associated with suicidal behaviour

TRYPTOPHAN HYDROXYLASE 2 (TPH 2) SINGLE NUCLEOTIDE POLYMORPHISMS, SUICIDE, AND ALCOHOL-RELATED SUICIDE

Background: Suicide has been identified as a serious public health problem that is often accompanied by alcohol misuse and dependence. It seems that suicide is a result of an interplay between distal (e.g. genetic loading, family history of suicide) and proximal factors (e.g. existence of psychiatric disorder, events conferring acute stress), as well as their interactions. However, like suicide, alcohol dependence seems to be a multifactorial disorder caused by genetic and environmental factors. Serotonergic dysfunction has been implicated to be involved in the pathophysiology of substance abuse, and has also an important role in suicidal behaviour. Studies investigating suicide, alcohol-related suicide and the rate limiting enzyme of serotonin synthesis, tryptophan hydroxylase 2 (TPH2), remain to date rather limited. Results: Recent studies of TPH2 showed a range of strong, mild or no association with suicide and alcohol-related suicide, depending on a study group and genetic variants tested. Overall, to date the clinical effects seems to be quite modest. Among suicide victims with more impulsive and verbal aggressive behaviour more alcohol misuse or dependency was present. Conclusions: Suicide and alcoholism are often comorbid disorders with a complex nature. They are both strongly linked to serotonin modulation, and therefore association studies of SNPs in genes from the serotonergic system could provide an insight into the genetic background of such disorders. However, based on current results we cannot draw any conclusions, but further research to clarify the interplay between serotonergic system dysfunction, suicide, alcohol dependence, impulsivity and the role of TPH2 enzyme is needed

GENOME-WIDE DNA METHYLATION PATTERNS IN SUICIDE VICTIMS: IDENTIFICATION OF NEW CANDIDATE GENES

Suicide is a major global public health problem with significant impact on society. According to the World Health Organization, every year about 800.000 people commit suicide, while at the global level suicide accounts for 50 % of all violent deaths among men and for 71 % among women. Suicide is a complex phenomenon which cannot be attributed to a single causal factor, but to a combination of simultaneous effects of multiple factors which are expressed in the form of psychological, biological and sociological indicators. Analysis of epigenetic mechanisms (methylation of the DNA, modifications of histone proteins and (networks of) miRNA), which link the interaction between genes and the environment, could importantly contribute to better understanding of suicidal behaviour. Recent studies on suicidal behaviour and DNA methylation show differences in DNA methylation pattern, with numerous sites among suicide victims. Using next generation sequencing, genome-wide studies helped identify novel candidate genes while studies of already known candidate genes (such as glucocorticoid receptor and BDNF) gave us better insight into the interplay of genetics and epigenetics. Epigenetic studies importantly contribute to elucidation of new biomarkers for suicidal behaviour. However, present studies are very different in design and often performed on very small samples, and these limitations could be overcome with more careful study preparation

Genetic predisposition of suicidal behavior: variants in GRIN2B, GABRG2, and ODC1 genes in suicide attempt and completed suicide In two Balkan populations

Introduction: Suicidal behavior ranges between suicidal ideation and completed suicide. Completed suicide accounts for over 700,000 deaths worldwide, while attempted suicide is 20 times more frequent. Genetic background is an important factor contributing to suicidal behavior, and candidate genes linked to several neurotransmitter systems have been investigated. Alternations in glutamate, γ-aminobutyric acid (GABA) and polyamine systems have been detected in suicidal behavior. Our aim was to differentiate genetic predispositions underlying two different types of suicidal behavior, attempted and completed suicide, in two Balkan populations. Methods: The study sample included 173 suicide attempters with comorbid psychiatric disorders (major depressive disorder, bipolar affective disorder, or schizophrenia), 216 non-suicidal psychiatric patients and 172 healthy controls from Serbia, and 333 suicide completers and 356 non-suicidal autopsy controls from Slovenia. Variants in the genes GRIN2B (rs2268115 and rs220557), GABRG2 (rs424740), and ODC1 (rs1049500 and rs2302614) were genotyped by TaqMan assays and analyzed using PLINK. Results: The CA genotype of rs220557 in the GRIN2B gene increases the risk for completed suicide (OR=1.51, p=0.021), and particularly violent suicide (OR=1.49, p=0.037), compared to controls. In the ODC1 gene, the CA genotype of rs2302614 decreases the risk for completed suicide compared to suicide attempt (OR=0.32, p=0.012). Marginally, the AC haplotype for variants rs1049500-rs2302614 in the ODC1 gene decreases the risk for completed suicide compared to suicide attempt (OR=0.50, p=0.052). Conclusion: Specific genetic variants of the glutamate and the polyamine systems are differently distributed among diverse suicidal phenotypes, thus providing further information on the implication of these systems in suicidality

Nanotechnology Meets Oncology: Nanomaterials in Brain Cancer Research, Diagnosis and Therapy

Advances in technology of the past decades led to development of new nanometer scale diagnosis and treatment approaches in cancer medicine leading to establishment of nanooncology. Inorganic and organic nanomaterials have been shown to improve bioimaging techniques and targeted drug delivery systems. Their favorable physico-chemical characteristics, like small sizes, large surface area compared to volume, specific structural characteristics, and possibility to attach different molecules on their surface transform them into excellent transport vehicles able to cross cell and/or tissue barriers, including the blood–brain barrier. The latter is one of the greatest challenges in diagnosis and treatment of brain cancers. Application of nanomaterials can prolong the circulation time of the drugs and contrasting agents in the brain, posing an excellent opportunity for advancing the treatment of the most aggressive form of the brain cancer—glioblastomas. However, possible unwanted side-effects and toxicity issues must be considered before final clinical translation of nanoparticles

Neuroepigenetics of psychiatric disorders

Understanding the pathology of psychiatric disorders is challenging due to their complexity and multifactorial origin. However, development of high-throughput technologies has allowed for better insight into their molecular signatures. Advancement of sequencing methodologies have made it possible to study not only the protein-coding but also the noncoding genome. It is now clear that besides the genetic component, different epigenetic mechanisms play major roles in the onset and development of psychiatric disorders. Among them, examining the role of long noncoding RNAs (lncRNAs) is a relatively new field. Here, we present an overview of what is currently known about the involvement of lncRNAs in schizophrenia, major depressive and bipolar disorders, as well as suicide. The diagnosis of psychiatric disorders mainly relies on clinical evaluation without using measurable biomarkers. In this regard, lncRNA may open new opportunities for development of molecular tests. However, so far only a small set of known lncRNAs have been characterized at molecular level, which means they have a long way to go before clinical implementation. Understanding how changes in lncRNAs affect the appearance and development of psychiatric disorders may lead to a more classified and objective diagnostic system, but also open up new therapeutic targets for these patients

Nanotechnology meets oncology

Advances in technology of the past decades led to development of new nanometer scale diagnosis and treatment approaches in cancer medicine leading to establishment of nanooncology. Inorganic and organic nanomaterials have been shown to improve bioimaging techniques and targeted drug delivery systems. Their favorable physico-chemical characteristics, like small sizes, large surface area compared to volume, specific structural characteristics, and possibility to attach different molecules on their surface transform them into excellent transport vehicles able to cross cell and/or tissue barriers, including the blood-brain barrier. The latter is one of the greatest challenges in diagnosis and treatment of brain cancers. Application of nanomaterials can prolong the circulation time of the drugs and contrasting agents in the brain, posing an excellent opportunity for advancing the treatment of the most aggressive form of the brain cancer-glioblastomas. However, possible unwanted side-effects and toxicity issues must be considered before final clinical translation of nanoparticles