Understanding the crosstalk of molecular factors and signaling pathways reveals novel biomarkers of cisplatin resistance in testicular germ cell tumors.

Testicular germ cell tumors (TGCTs) mostly affect young men, but fortunately belong to well curable solid tumors. Today, different treatment strategies are applied reaching excellent outcomes, and introduction of alternative approach of patient active surveillance or adjuvant chemotherapy after orchiectomy decreases number of unnecessary toxic treatments of young patients. Also for relapsing patients, salvage therapy offers high survival rates. However, small percentages of affected young men do not respond to conventional therapy regimen due to intrinsic or acquired therapy resistance. For closely watching of patients during active surveillance, patients' stratification due to their prognosis, detection of therapy resistance and early relapse before treatment initiation, reliable molecular biomarkers and diagnostic tools replacing conventional approaches are still needed. Complex understanding of disease development and progression as well as mechanisms of chemoresistance and their epigenetic or chronobiological regulation pre-requisite successful search for such novel biomarkers. In this review, we aimed to highlight the importance of crosstalk of different regulatory mechanisms and their key players affecting treatment response, and focus on their potential as novel molecular biomarkers and/or druggable targets.

Evaluation of expression profiles of microRNAs and two target genes, FOXO3a and RUNX2, effectively supports diagnostics and therapy predictions in breast cancer.

Breast cancer (BC) including its progression into bone metastasis is a complex process involving changes in gene expression and function of both, microRNAs (miRNAs) and their target genes. Deregulation of miRNAs has been described as a crucial factor responsible for the initiation and progression of BC, and specific miRNA expression profiles have been found to be associated with particular disease states, histological tumor types, and BRCA1/2 or HER status. BRCA1 tumor suppressor is involved in DNA damage response and repair and epigenetically controls miR-155 expression and its pre-cancerous potential. MiR-155 targets 3´UTR region of multiple components of the pro-oncogenic signaling cascades, including FOXO3a tumor suppressor and RUNX2 transcription factor regulating metastatic potential in BC. We employed qRT-PCR to determine expression level and examine possible regulatory role of selected miRNAs (miR-17, miR-18a, miR-19a, miR-20a, miR-21, miR-27a and miR-155) and their impact on expression modulation of FOXO3a and RUNX2 in peripheral blood mononuclear cells (PBMCs) in healthy individuals, in women carrying BRCA1 mutations with no disease manifestation, in women carrying BRCA1 mutations after tumor resection and therapy and in women with BC of unknown BRCA1 status in acute stage before tumor resection. Our results showed significant increase of miR-17, miR-19a, miR-21, miR-27, miR-155 and RUNX2 expression in PBMCs in BRCA1 patients and patients in acute stage, while FOXO3a expression was significantly decreased in these patients. MiR-18a and miR-20a expression was not affected. We propose that expressional changes reported in this study could provide significant additive information for early BC diagnosis, disease development prediction and therapy outcome monitoring.

microRNA expression profiling as supportive diagnostic and therapy prediction tool in chronic myeloid leukemia.

Chronic myeloid leukemia (CML) is a myeloproliferative disorder of hematopoietic stem cells carrying Philadelphia (Ph) chromosome and the oncogenic BCR-ABL1 fusion gene. microRNAs (miRNAs) belong to hematopoiesis transcription regulators and their deregulated expression associates with pathogenesis of CML. The current study assesses and validates expression profiles of selected oncogenic and tumor suppressing miRNAs that are associated with different imatinib mesylate (IM) response in CML patients carrying rare BCR-ABL variants. Microarray analysis has identified different expression of 70 miRNAs (46 up- and 24 down-regulated) when compared IM-resistant with IM-responsive patients carrying Ph chromosome. Significantly up-regulated expression of oncogenic miRNAs (miR-17, miR-18a, miR-20a, miR-21, miR-27a and miR-155) and significantly down-regulated expression of tumor supressing mRNAs (let-7d, miR-205, miR-320, miR-451 and miR-574) in IM-resistant compared to IM-responsive patients was confirmed and validated by qRT-PCR. This study confirms the involvement of the selected oncogenic and tumor suppressing miRNAs in CML pathogenesis and IM response and suggests that these miRNAs could be suitable biomarkers for differential diagnosis of CML patients carrying rare BCR-ABL transcripts, as well as for prediction of their IM response and therapy outcome.

miR-155 as a diagnostic and prognostic marker in hematological and solid malignancies.

MicroRNAs (miRNAs) are small RNAs that have emerged as potent regulators of the target genes messenger RNAs expression in the response of cell to both physiological and pathophysiological conditions. Reflecting pathological processes today, miRNAs are widely validated for their potential role in diagnostic, prognostic and novel therapeutic targeting for cancerous and other diseases. miR-155 is considered as a typical multifunctional miRNA including its role as oncomiR (cancer-associated miRNA). Expression of miR-155 is upregulated in cells with high proliferative activity and decreased apoptotic capability. It belongs to cluster of well-characterized tumor associated miRNAs detectable also in the peripheral blood. In this review we summarize the principles of miR-155 host gene expressional regulation, as well as its role in regulation of the target genes mRNAs. Altered expression of miR-155 has been described in multiple cancerous and other diseases, reflecting staging, progress and treatment outcomes. Therefore, miR-155 became a potential biomarker and candidate for clinical utilization as predictor of the presence of cancer, its staging and prognosis.

Modulation of expression of the sigma receptors in the heart of rat and mouse in normal and pathological conditions.

The aim of the present work was to study the effect of various stressors (hypoxia, cold, immobilization) on the gene expression of sigma receptors in the left ventricles of rat heart. We have clearly shown that gene expression of sigma receptors is upregulated by strong stress stimuli, such as immobilization and/or hypoxia. Nevertheless, cold as a milder stressor has no effect on sigma receptor's mRNA levels. Signalling cascade of sigma receptors is dependent on IP(3) receptors, since silencing of both, type 1 and 2 IP(3) receptors resulted in decreased mRNA levels of sigma receptors. Physiological relevance of sigma receptors in the heart is not clear yet. Nevertheless, based on the already published data we can assume that sigma receptors might participate in contractile responses in cardiomyocytes.

Cardiovascular diseases and molecular variants of the renin-angiotensin system components in Slovak population.

Cardiovascular diseases associated with molecular variants of individual components of renin-angiotensin system are reported to constitute inherited predisposition in humans. Molecular variant frequencies are race- and population-dependent. We examined frequencies of the M235T variant of angiotensinogen gene and I/D polymorphism of gene for angiotensin-converting enzyme in Slovak population: in hypertensive patients, coronary heart disease (CHD), dilated cardiomyopathy (DCM) and myocardial infarction (MI) patients compared to healthy subjects. Frequency of M235T was significantly increased in hypertensive, CHD and DCM patients compared to controls (0.48 and 0.50 vs. 0.40, p < 0.001). Significant increase in D allele frequency compared to controls was observed in the group of patients after MI (0.58 vs. 0.50, p < 0.001), CHD (0.59 vs. 0.50, p < 0.001) and DCM (0.60 vs. 0.50, p < 0.001). These results correlate with other Caucasian populations. In Slovak population, M235T is associated with increased blood pressure and D allele of ACE gene is associated with MI, chronic CHD and DCM, rather than with hypertension. Our results suggest that in Slovak population, D alelle and M235T variant represent a risk factor for several cardiovascular diseases and these polymorphisms might have a cumulative effect on development of cardiovascular diseases.

Effect of aging on the expression of intracellular Ca(2+) transport proteins in a rat heart.

Aging process is accompanied by various biological dysfunctions including altered calcium homeostasis. Modified calcium handling might be responsible for changed cardiac function and potential development of the pathological state. In the present study we compared the mRNA and protein levels of the intracellular Ca(2+)-handling proteins--inositol 1,4,5-trisphosphate receptor (IP(3)R), ryanodine receptor (RyR), sarcoplasmic reticulum Ca(2+) pump (SERCA2), and also transient receptor potential C (TRPC) channels in cardiac tissues of 5-, 15-, and 26-month-old rats. Aging was accompanied by significant increase in the mRNA levels of IP(3)R and TRPC channels in both ventricles and atria, but mRNA level of the type 2 RyR was unchanged. Protein content of the IP(3)R1 correlated with mRNA levels, in the left ventricle of 15- and 26-month-old rats the value was approximately 1.8 and 2.8-times higher compared to 5-month-old rats. No significant differences were observed in mRNA and protein levels of the SERCA2 among 5-month-old and aged rats. However, Ca(2+)-ATPase activity significantly decreased with age, activities in 5-, 15-, and 26-month-old rats were 421.2 +/- 13.7, 335.5 +/- 18.1 and 304.6 +/- 14.8 nmol P(i) min(-1) mg(-1). These results suggest that altered transporting activity and/or gene expression of Ca(2+)-handling proteins of intracellular Ca(2+) stores might affect cardiac function during aging.

Adrenergic and calcium modulation of the heart in stress: from molecular biology to function.

There is strong evidence about the importance of catecholamines and calcium signaling in heart function. Also, interaction of these two systems is well documented. Catecholamines signal through adrenergic receptors, and further activate calcium transport either from the extracellular space, or from the intracellular calcium stores. This review summarizes current knowledge on catecholamine production in the heart, with special focus on the final enzyme in the catecholamine synthesizing pathway, phenylethanolamine N-methyltransferase (PNMT), in different cell types in the heart. Further, signaling through different types of adrenergic receptors in physiological conditions and after exposure to different stressors is discussed. Also, part of this review considers activation of an intracellular calcium transport system via inositol 1,4,5-trisphosphate receptor and to possible functional consequences in control and stress conditions.

Modulation of expression of Na+/Ca2+ exchanger in heart of rat and mouse under stress.

AIM: The Na(+)/Ca(2+) exchanger (NCX) is a major Ca(2+) extrusion system in the plasma membrane of cardiomyocytes and an important component participating on the excitation-contraction coupling process in muscle cells. NCX1 isoform is the most abundant in the heart and is known to be changed after development of ischaemia or myocardial infarction. Objective of this study was to investigate the effect of stress factors (immobilization, cold and short-term hypoxia) on the expression of NCX1, in vivo, in the heart of rat and mouse. METHODS: We compared gene expression and protein levels of control and stressed animals. The activity of NCX was measured by the whole cell configuration using the patch clamp. We also measured physiological parameters of the heart in physiological conditions and under ischaemia-reperfusion to compare response of control and stressed hearts. RESULTS: We have found that only strong stress stimulus (hypoxia, immobilization) applied repeatedly for several days elevated the NCX1 mRNA level. Cold, which is a weaker stressor that activates mainly sympathoneural, and only marginally adrenomedullary system did not affect the gene expression of NCX1. Thus, from these results it appears that hormones produced by the adrenal medulla (mainly adrenaline) might be involved in this process. To study possible mechanism of the NCX1 regulation by stress, we focused on the possible role of the hypothalamo-pituitary-adrenocortical pathway in the activation of catecholamine synthesis in the adrenal medulla. We have already published that cortisol affects activity, but not the gene expression of NCX1. In this work, we used corticotropin-releasing hormone (CRH) knockout mice, where secretion of corticosterone and subsequently adrenaline is significantly suppressed. As no increase in NCX1 mRNA was observed in CRH knockout mice due to immobilization stress, we proposed that adrenaline (probably regulated via corticosterone) is involved in the regulation of NCX1 gene expression during stress. CONCLUSIONS: The gene expression and protein levels of the NCX1 are increased by the strong stress stimuli, e.g. hypoxia, or immobilization stress. The activity of NCX1 is decreased. Based on these results, we assume that the gene expression of NCX is increased as a consequence of suppressed activity of this transport system.

Hypoxia modulates gene expression of IP3 receptors in rodent cerebellum.

Hypoxic brain cell injury is a complex process that results from a series of intracellular events. In this work, we tested whether severe hypoxia for 6 h can affect gene expression and protein levels of intracellular calcium channels, ryanodine receptors, and inositol 1,4,5-trisphosphate receptors in mouse cerebellum. In addition, we tested the effect of hypoxia on cerebellar granular cells of rats. We have found that gene expression of types 1 and 2 IP(3) receptors is significantly increased after the exposure of mice to hypoxic stimulus for 6 h and also in rat cerebellar granular cells. Increased gene expression of IP(3) receptors was reflected in increased protein levels of these channels as well. In this process, reactive oxygen species are most probably involved, as antioxidant quercetin abolished hypoxia-induced increase in both types 1 and 2 IP3 receptor. Ryanodine receptors of types 1 and 2 and sarco(endo)plasmic reticulum Ca(2+)-ATPase were not affected by hypoxia on the level of messenger RNA. To test physiological consequences, we measured levels of intracellular calcium. We observed significantly elevated calcium level in hypoxic compared to normoxic cells. Deeper understanding of mechanisms, through which hypoxia regulates intracellular calcium, could point towards the development of new therapeutic approaches to reduce or suppress the pathological effects of cellular hypoxia, such as those seen in stroke or ischemia.

Is the ApoE polymorphism associated with dilated cardiomyopathy?

Apolipoprotein E (ApoE) is 34 kDa protein involved in the modulation of cholesterol transport and homeostasis. Polymorphism of the ApoE gene has been implicated in many chronic cardiovascular and neuronal diseases. ApoE epsilon4 allele has been reported to be associated with increased risk of cardiovascular diseases such as myocardial infarction, hypertension, coronary heart disease, etc. Fifty patients with the end-stage dilated cardiomyopathy (DCM) and advanced congestive heart failure were examined in our study. For evaluation of ApoE polymorphism, novel approach of fast screening of ApoE gene polymorphism by combination of PCR and blotting (CVD StripAssay) was used. Individual genotypes were correlated with basic cardiologic clinical parameters. The reported frequency of this allele in Caucasian population is 14.7 %. Our results showed that in patients with DCM frequency of the ApoE epsilon4 allele is 40 %. Frequency of the genotype epsilon2/4 was 58 % and epsilon3/4 was 22 %. Comparison with control Caucasian groups monitored by others clearly revealed that frequency of epsilon4 alelle is increased in patients with advanced stages of DCM. This observation suggests association of ApoE polymorphism with severe form of DCM. Physiological consequences of this observation remain to be clarified.

Effect of two distinct stressors on gene expression of the type 1 IP3 receptors.

Inositol 1,4,5-trisphosphate (IP3) is one of the second messengers, which triggers calcium release from intracellular pools via IP3 receptors. Previously we have shown that single immobilization stress increased gene expression of both, the type 1 and type 2 IP3 receptors (IP3R1 and IP3R2, respectively). In this study we evaluated whether long-term exposure to softer stressor (cold exposure to 4 degrees C) can affect the response to single immobilization stress. We examined modulation of the type 1 IP3 receptor gene expression by each stressor separately, and then in their combination. Rats were immobilized for 30 min and 120 min and were decapitated immediately or 3 h after immobilization. Cold stress was performed by exposure of animals to 4 degrees C temperature for 1, 7 and 28 days. To determine the effect of both stressors in combination, animals exposed to cold for 28 days were afterwards exposed to immobilization for 120 min and decapitated 3 h after the end of stressful stimulus. Our results verify that single immobilization increases the IP3R1 gene expression in left atria of rat heart, while cold stress elevates the level of gene expression only after the exposure to cold for 7 days. The exposure to cold for 28 days did not increase the gene expression of the type 1 IP3 receptor compared to control. Application of both stressors (28 days of cold exposure followed by 120 min of immobilization with subsequent 3 h rest) showed the tendency of increased IP3R1 gene expression compared to absolute, nonstressed control, but level of the type 1 IP3 receptor mRNA was significantly lower compared to mRNA levels of solely immobilized animals. Thus, cold exposure affects the response of the gene expression of the type 1 IP3 receptor to immobilization stress.

Identification of a novel membrane-associated protein expressed in neurons of the squid and rodent nervous systems.

In a previous communication, we reported the isolation of a novel cDNA clone (pA6) from a library constructed from squid axonal mRNAs. The partial cDNA clone contained a unique open reading frame that encoded 84 amino acids and was complementary to a moderately abundant mRNA approximately 550-600 nucleotides in length [Chun et al., J. Neurosci. Res. 49 (1997) 144-153]. In this report, we identify the pA6 gene product, and characterize its expression in the squid and rodent brain. Results of immunoblot analyses conducted in squid, using a polyclonal antibody raised against a synthetic peptide corresponding to the C-terminus of the putative protein, established the presence of two pA6 immunoreactive proteins of approximately 14 kDa and 26 kDa in size. In contrast, mouse brain contained only a single 26-kDa immunoreactive species. In both the squid and mouse brain, the expression of pA6 appears highly selective, being detected in certain neurons but not in non-neuronal cells, as judged by both in situ hybridization and immunocytochemistry. Findings derived from light microscopic, double-label immunohistofluorescence studies indicate that pA6 protein co-localizes with prohibitin, a mitochondrial marker protein. Consistent with these results, electron microscopy localized pA6 immunoreactivity to several membrane compartments to include the outer membrane of mitochondria, as well as to the smooth endoplasmic reticulum and tubulovesicles in dendrites, axons, and axon terminals of neurons in the rat brain. Taken together, these findings indicate that pA6 is a novel, membrane-associated protein, which is expressed in the distal structural/functional domains of neurons in both the invertebrate and vertebrate nervous systems.

Changes in angiotensin AT1 receptor mRNA levels in the rat brain after immobilization stress and inhibition of central nitric oxide synthase.

OBJECTIVE: To study functional interactions between angiotensin II AT1 receptors and nitric oxide (NO) activity in different brain areas in rats exposed to immobilization stress. METHODS: Central inhibition of nitric oxide synthase (NOS) was provided by intracerebroventricular (i.c.v.) administration of (N-omega-nitro-L-arginine-methylester) L-NAME and analysis of AT1 receptor mRNA was performed using semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) technique. The immobilization in prone position lasted 2 hrs and the rats were sacrificed 24 hr later. The hypothalamus, hippocampus, thalamus, and cortex were isolated from fresh brains. RESULTS: In the cortex, gene expression of AT1 receptors was unaffected either by L-NAME treatment, or by a single exposure to immobilization stress for 2 hours followed by 24 hours of rest. In the hippocampus, the repeated treatment with L-NAME increased mRNA levels of AT1 receptors approximately 9-times compared to those in the control (untreated) group. Immobilization also increased AT1 receptor mRNA levels in the hippocampus which was similar to that induced by the L-NAME. The increase of AT1 receptor mRNA levels in the hippocampus of immobilized rats was not further altered when the animals were pretreated with L-NAME. In control rats, exposure to immobilization resulted in a significant rise in mRNA levels coding for AT1 receptors in the hypothalamus, but not in the thalamus. L-NAME treatment showed a tendency of increase in AT1 receptor mRNA levels in the hypothalamus. Moreover, when animals treated with L-NAME were subjected to immobilization, a further increase in AT1 receptor mRNA levels was observed in the hypothalamus in comparison with corresponding controls. CONCLUSIONS: The present data indicate that a single immobilization stress results in increased gene expression of AT1 receptors in the hypothalamus and hippocampus. The rise in AT1 mRNA levels in the same brain structures after repeated treatment with L-NAME allow to suggest an interaction between the central angiotensin II and nitric oxide.

Molecular characterization of the mouse Tem1/endosialin gene regulated by cell density in vitro and expressed in normal tissues in vivo.

Human tumor endothelial marker 1/endosialin (TEM1/endosialin) was recently identified as a novel tumor endothelial cell surface marker potentially involved in angiogenesis, although no specific function for this novel gene has been assigned so far. It was reported to be expressed in tumor endothelium but not in normal endothelium with the exception of perhaps the corpus luteum. Here we describe the cDNA and genomic sequences for the mouse Tem1/endosialin homolog, the identification and characterization of its promoter region, and an extensive characterization of its expression pattern in murine and human tissues and murine cell lines in vitro. The single copy gene that was mapped to chromosome 19 is intronless and encodes a 92-kDa protein that has 77.5% overall homology to the human protein. The remarkable findings are 1) this gene is ubiquitously expressed in normal human and mouse somatic tissues and during development, and 2) its expression at the mRNA level is density-dependent and up-regulated in serum-starved cells. In vitro, its expression is limited to cells of embryonic, endothelial, and preadipocyte origin, suggesting that the wide distribution of its expression in vivo is due to the presence of vascular endothelial cells in all the tissues. The ubiquitous expression in vivo is in contrast to previously reported expression limited to corpus luteum and highly angiogenic tissues such as tumors and wound tissue.

Different expression of renin-angiotensin system components in hearts of normotensive and hypertensive rats.

Tissue renin-angiotensin systems are known to behave differently from the circulating renin-angiotensin system (RAS). It has already been proposed that not only the circulating RAS, but also RAS localized in the cardiac tissue plays an important role in the heart failure. The objective of this study was to compare the gene expression of individual components of the renin-angiotensin system in hearts of normotensive and hypertensive rats. Two genetically hypertensive rat strains--spontaneously hypertensive rats (SHR) and hereditary hypertriglyceridemic rats (HTG)--were compared with Wistar-Kyoto (WKY) and Lewis (LEW) normotensive controls. In addition, developmental changes in gene expression of individual components of cardiac RAS were studied in 20-day-old fetuses, 2-day-old newborns and 3-month-old HTG and LEW rats. In our study, the angiotensinogen gene expression did not differ either among adult normotensive and hypertensive strains, or during development. In contrast, the renin gene expression was significantly increased in hearts of hypertensive compared to normotensive rats. Moreover, a 5-fold increase of renin mRNA was observed in hearts of HTG rats between day 2 and the third month of age. There was also an age-dependent increase of ACE gene expression in both HTG and LEW rats which was substantially delayed in HTG hearts. In conclusion, the results of our study suggest that overexpression of the cardiac renin gene in hypertensive strains could participate in the structural and functional changes of the heart during the development of hypertension.

Expression of cardiac renin and its modulation by stress in normotensive and hypertensive rats.

Renin is the rate-limiting step in angiotensin II production. Existence of the cardiac renin is still ambiguous in healthy animals, although there is evidence that under some pathological conditions the heart might express mRNA for renin. Therefore, the aim of the present study was to (i) detect the renin gene expression in the whole rat heart, ventricles, atria and in isolated and purified myocytes, (ii) determine the effect of stress on renin mRNA and protein levels, and (iii) compare the response of renin gene expression to stress in normotensive and spontaneously hypertensive rats. Renin mRNA was determined by reverse transcription and polymerase chain reaction and quantified relatively to beta-actin and glyceraldehyde-3-phosphate dehydrogenase. Protein message was detected by monoclonal antibody against renin. Renin mRNA was found in all parts of the heart and in myocytes. Renin protein was found in the heart ventricles and atria, but not in cardiomyocytes. Immobilization stress affected renin on both, the mRNA and the protein level. The effect of stress was observed in the hearts of normotensive, but not in genetically hypertensive rats. Thus, renin might be involved in the development of the pathophysiological state in rat heart.