Ditte Andreasen

Assessing sample and miRNA profile quality in serum and plasma or other biofluids.

MicroRNAs (miRNAs) constitute a class of small cellular RNAs (typically 21-23nt) that function as post-transcriptional regulators of gene expression. Current estimates indicate that more than one third of the cellular transcriptome is regulated by miRNAs, although they are relatively few in number (less than 2000 human miRNAs). The high relative stability of miRNA in common clinical tissues and biofluids (e.g. plasma, serum, urine, saliva, etc.) and the ability of miRNA expression profiles to accurately classify discrete tissue types and disease states have positioned miRNA quantification as a promising new tool for a wide range of diagnostic applications. Furthermore miRNAs have been shown to be rapidly released from tissues into the circulation with the development of pathology. To facilitate discovery and clinical development of miRNA-based biomarkers, we developed a genome-wide Locked Nucleic Acid (LNA™)-based miRNA qPCR platform with unparalleled sensitivity and robustness. The platform allows high-throughput profiling of miRNAs from important clinical sources without the need for pre-amplification. Using this system, we have profiled thousands of biofluid samples including blood derived plasma and serum. An extensive quality control (QC) system has been implemented in order to secure technical excellence and reveal any unwanted bias coming from pre-analytical or analytical variables. We present our approaches to sample and RNA QC as well as data QC and normalization. Specifically we have developed normal reference ranges for circulating miRNAs in serum and plasma as well as a hemolysis indicator based on microRNA expression.

Vascular Smooth Muscle Cells Express the α1A Subunit of a P-/Q-Type Voltage-Dependent Ca2+Channel, and It Is Functionally Important in Renal Afferent Arterioles

In the present study, we tested whether the &agr;1A subunit, which encodes a neuronal isoform of voltage-dependent Ca2+ channels (VDCCs) (P-/Q-type), was present and functional in vascular smooth muscle and renal resistance vessels. By reverse transcription–polymerase chain reaction and Southern blotting analysis, mRNA encoding the &agr;1A subunit was detected in microdissected rat preglomerular vessels and vasa recta, in cultures of rat preglomerular vascular smooth muscle cells (VSMCs), and in cultured rat mesangial cells. With immunoblots, &agr;1A subunit protein was demonstrated in rat aorta, brain, aortic smooth muscle cells (A7r5), VSMCs, and mesangial cells. Immunolabeling with an anti-&agr;1A antibody was positive in acid-macerated, microdissected preglomerular vessels and in A7r5 cells. Patch-clamp experiments on aortic A7r5 cells showed 22±4% (n=6) inhibition of inward Ca2+ current by &ohgr;-Agatoxin IVA (10–8 mol/L), which in this concentration is a specific inhibitor of P-type VDCCs. Measurements of intracellular Ca2+ in afferent arterioles with fluorescence-imaging microscopy showed 32±9% (n=10) inhibition of the K+-induced rise in Ca2+ in the presence of 10–8 mol/L &ohgr;-Agatoxin IVA. In microperfused rabbit afferent arterioles, &ohgr;-Agatoxin IVA inhibited depolarization-mediated contraction with an EC50 of 10–17 mol/L and complete blockade at 10–14 mol/L. We conclude that the &agr;1A subunit is expressed in VSMCs from renal preglomerular resistance vessels and aorta, as well as mesangial cells, and that P-type VDCCs contribute to Ca2+ influx in aortic and renal VSMCs and are involved in depolarization-mediated contraction in renal afferent arterioles.

Control of renin secretion from rat juxtaglomerular cells by cAMP-specific phosphodiesterases.

We tested the hypothesis that cGMP stimulates renin release through inhibition of the cAMP-specific phosphodiesterase 3 (PDE3) in isolated rat juxtaglomerular (JG) cells. In addition, we assessed the involvement of PDE4 in JG-cell function. JG cells expressed PDE3A and PDE3B, and the PDE3 inhibitor trequinsin increased cellular cAMP content, enhanced forskolin-induced cAMP formation, and stimulated renin release from incubated and superfused JG cells. Trequinsin-mediated stimulation of renin release was inhibited by the permeable protein kinase A antagonist Rp-8-CPT-cAMPS. PDE4C was also expressed, and the PDE4 inhibitor rolipram enhanced cellular cAMP content. Dialysis of single JG cells with cAMP in whole-cell patch-clamp experiments led to concentration-dependent, biphasic changes in cell membrane capacitance (Cm) with a marked increase in Cm at 1 &mgr;mol/L, no net change at 10 &mgr;mol/L, and a decrease at 100 &mgr;mol/L cAMP. cGMP also had a dual effect on Cm at 10-fold higher concentration compared with cAMP. Trequinsin, milrinone, and rolipram mimicked the effect of cAMP on Cm. Trequinsin, cAMP, and cGMP enhanced outward current 2- to 3-fold at positive membrane potentials. The effects of cAMP, cGMP, and trequinsin on Cm and cell currents were abolished by inhibition of protein kinase A with Rp-cAMPs. We conclude that degradation of cAMP by PDE3 and PDE4 contributes to regulation of renin release from JG cells. Our data provide evidence at the cellular level that stimulation of renin release by cGMP involves inhibition of PDE3 resulting in enhanced cAMP formation and activation of the cAMP sensitive protein kinase.

Molecular and Functional Identification of Cyclic AMP-Sensitive BKCa Potassium Channels (ZERO Variant) and L-Type Voltage-Dependent Calcium Channels in Single Rat Juxtaglomerular Cells

Abstract— This study aimed at identifying the type and functional significance of potassium channels and voltage-dependent calcium channels (Cav) in single rat JG cells using whole-cell patch clamp. Single JG cells displayed outward rectification at positive membrane potentials and limited net currents between −60 and −10 mV. Blockade of K+ channels with TEA inhibited 83% of the current at +105 mV. Inhibition of KV channels with 4-AP inhibited 21% of the current. Blockade of calcium-sensitive voltage-gated K+ channels (BKCa) with charybdotoxin or iberiotoxin inhibited 89% and 82% of the current, respectively. Double immunofluorescence confirmed the presence of BKCa and renin in the same cell. cAMP increased the outward current by 1.6-fold, and this was inhibited by 74% with iberiotoxin. Expression of the cAMP-sensitive splice variant (ZERO) of BKCa was confirmed in single-sampled JG cells by RT-PCR. The resting membrane potential of JG cells was −32 mV and activation of BKCa with cAMP hyperpolarized cells on average 16 mV, and inhibition with TEA depolarized cells by 17 mV. The cells displayed typical high-voltage activated calcium currents sensitive to the L-type Cav blocker calciseptine. RT-PCR analysis and double-immunofluorescence labeling showed coexpression of renin and L-type Cav 1.2. The cAMP-mediated increase in exocytosis (measured as membrane capacitance) was inhibited by depolarization to +10 mV, and this inhibitory effect was blocked with calciseptine, whereas K+-blockers had no effect. We conclude that JG cells express functional cAMP-sensitive BKCa channels (the ZERO splice variant) and voltage-dependent L-type Ca2+ channels.

Coexpression of Voltage-Dependent Calcium Channels Cav1.2, 2.1a, and 2.1b in Vascular Myocytes

Voltage-dependent Ca2+ channels Cav1.2 (L type) and Cav2.1 (P/Q type) are expressed in vascular smooth muscle cells (VSMCs) and are important for the contraction of renal resistance vessels. In the present study we examined whether native renal VSMCs coexpress L-, P-, and Q-type Ca2+ currents. The expression of both Cav2.1a (P-type) and Cav2.1b (Q-type) mRNA was demonstrated by RT-PCR in renal preglomerular vessels from rats and mice. Immunolabeling was performed on A7r5 cells, renal cryosections, and freshly isolated renal VSMCs with anti-Cav1.2 and anti-Cav2.1 antibodies. Conventional and confocal microscopy revealed expression of both channels in all of the smooth muscle cells. Whole-cell patch clamp on single preglomerular VSMCs from mice showed L-, P-, and Q-type currents. Blockade of the L-type currents by calciseptine (20 nmol/L) inhibited 35.6±3.9% of the voltage-dependent Ca2+ current, and blocking P-type currents (&ohgr;-agatoxin IVA 10 nmol/L) led to 20.2±3.0% inhibition, whereas 300 nmol/L of &ohgr; agatoxin IVA (blocking P/Q-type) inhibited 45.0±7.3%. In rat aortic smooth muscle cells (A7r5), blockade of L-type channels resulted in 28.5±6.1% inhibition, simultaneous blockade of L-type and P-type channels inhibited 58.0±11.8%, and simultaneous inhibition of L-, P-, and Q-type channels led to blockade (88.7±5.6%) of the Ca2+ current. We conclude that aortic and renal preglomerular smooth muscle cells express L-, P-, and Q-type voltage-dependent Ca2+ channels in the rat and mouse.

Clinical Implications of Monitoring Circulating Tumor DNA in Patients with Colorectal Cancer

Purpose: We investigated whether detection of ctDNA after resection of colorectal cancer identifies the patients with the highest risk of relapse and, furthermore, whether longitudinal ctDNA analysis allows early detection of relapse and informs about response to intervention. Experimental Design: In this longitudinal cohort study, we used massively parallel sequencing to identify somatic mutations and used these as ctDNA markers to detect minimal residual disease and to monitor changes in tumor burden during a 3-year follow-up period. Results: A total of 45 patients and 371 plasma samples were included. Longitudinal samples from 27 patients revealed ctDNA postoperatively in all relapsing patients (n = 14), but not in any of the nonrelapsing patients. ctDNA detected relapse with an average lead time of 9.4 months compared with CT imaging. Of 21 patients treated for localized disease, six had ctDNA detected within 3 months after surgery. All six later relapsed compared with four of the remaining patients [HR, 37.7; 95% confidence interval (CI), 4.2–335.5; P < 0.001]. The ability of a 3-month ctDNA analysis to predict relapse was confirmed in 23 liver metastasis patients (HR 4.9; 95% CI, 1.5–15.7; P = 0.007). Changes in ctDNA levels induced by relapse intervention (n = 19) showed good agreement with changes in tumor volume (κ = 0.41; Spearman ρ = 0.4). Conclusions: Postoperative ctDNA detection provides evidence of residual disease and identifies patients at very high risk of relapse. Longitudinal surveillance enables early detection of relapse and informs about response to intervention. These observations have implications for the postoperative management of colorectal cancer patients. Clin Cancer Res; 23(18); 5437–45. ©2017 AACR.

Abstract 3987: Exosomal microRNA in cell-free urine samples as a source for liquid prostate cancer biopsy

MicroRNAs constitute a class of small cellular RNAs (typically 19-23 nt) that function as post-transcriptional regulators of gene expression. Current estimates indicate that more than one third of the human cellular transcriptome is regulated by this small class of RNA (∼2000 miRNA). MicroRNAs have been shown to be actively exported from tissues into the circulation through a variety of mechanisms including complexing with RNA binding proteins or HDL and through active exosome transport. Exosomes are nanovesicles secreted into the extracellular environment by a wide range of cell types under normal and pathological conditions. As the profile of exosomal microRNAs may be a fingerprint of the releasing cell type and because they are released in easily accessible body fluids such as blood and urine, their microRNA content holds potential as biomarkers for early detection of malignancy. Cell free urine samples are an obvious liquid biopsy source for microRNA markers in prostate cancer and could serve as diagnostic tools as well as treatment response markers. Yet microRNA levels in urine samples are extremely sparse and cannot be detected reliable by conventional sample preparation methods. It has been reported that tumour derived exosomes carrying genetic information specific for prostate cancer can be measured in urine samples following prostate massage. However, a methodology eliminating the need for prostate massage of every patient to be tested in a clinical setting is highly desirable. The purpose of this study was to combine a simple exosomal enrichment method with our highly sensitive LNA™-based qPCR platform for detection of microRNAs and apply this to a cohort consisting of more than 300 cell free urine samples from prostate cancer cases and controls. In conclusion, cell free urine samples holds potential as a liquid biopsy source for exosomal microRNA markers in prostate cancer, showing miRNA signatures of strong diagnostic potential. Analysis is pending and data will be presented. Citation Format: Thorarinn Blondal, Anni R. Thomsen, Jorg Krummheuer, Michael Borre, Jacob Fredsoe, Christa Haldrup, Ditte Andreasen, Maria W. Teilum, Niels Tolstrup, Karina D. Sorensen, Torben F. Orntoft, Peter Mouritzen. Exosomal microRNA in cell-free urine samples as a source for liquid prostate cancer biopsy. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3987. doi:10.1158/1538-7445.AM2015-3987

Abstract B40: A two-microRNA signature in urinary exosomes for diagnosis of prostate cancer

Antibody based detection of circulating prostate specific antigen (PSA) remains an important test in the diagnosis of prostate cancer. Unfortunately the test identifies a high number of false positives which require further testing to confirm the presence of cancer including several biopsies taken from the prostate itself. Whereas the performance of biopsies on individuals is associated with discomfort and risk of serious side effects, the invasive test also represents an expense to health care systems. Given the high number of false positives, the PSA test is therefore the direct cause of unnecessary suffering of healthy individuals and costs to health systems. To investigate the possibilities for developing a non-invasive and more specific test, we have developed different technologies enabling the detection of prostate cancer microRNA biomarkers in exosomes derived from urine from non-prostate massaged men. The first of these technologies is a highly sensitive LNA™-based qPCR platform for microRNA detection, which enables profiling in biofluids where microRNA levels are extremely low. At this point we have already applied this platform on thousands of biofluid samples including serum/plasma and urine to establish normal reference ranges for circulating microRNAs as well as to identify biomarkers of disease. The second technology is a simple exosome precipitation system which only requires low speed centrifugation to harvest urine exosomes. We have combined our developed technologies and applied this on cell-free urine from two different cohorts of approximately 220 patients each, to identify a number of differentially regulated microRNAs in urine from prostate cancer bearing individuals. Prostate cancer specific signatures have been obtained by different combinations of these differentially regulated microRNAs. The smallest signature is composed of two microRNAs which allows constructing receiver operating characteristic curves with areas under the curve well above 0.8. Citation Format: Peter Mouritzen, Jacob Christian Fredsoe, Thorarinn Blondal, Anne Karin Rasmussen, Michael Borre, Christa Haldrup, Ditte Andreasen, Niels Tolstrup, Torben Falck Orntoft, Karina Dalsgaard Sorensen. A two-microRNA signature in urinary exosomes for diagnosis of prostate cancer. [abstract]. In: Proceedings of the AACR Special Conference on Noncoding RNAs and Cancer: Mechanisms to Medicines ; 2015 Dec 4-7; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2016;76(6 Suppl):Abstract nr B40.

Abstract 5233: MicroRNA in biofluid as robust biomarkers for cancer

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA microRNAs constitute a class of small cellular RNAs (typically 19-23 nt) that function as post-transcriptional regulators of gene expression. Current estimates indicate that more than one third of the human cellular transcriptome is regulated by this small class of RNA (∼2000 miRNA). The study of extracellular microRNAs and their potential as pathophysiological markers has greatly expanded in the last couple of years. microRNAs have been shown to be actively exported from tissues into the circulation through a variety of mechanisms including exosome and microvesicle transport, and complexing with RNA binding proteins or HDL. The high relative stability of microRNAs in common clinical source materials (FFPE blocks, plasma, serum, urine, saliva, etc.) and the ability of microRNA expression profiles to accurately classify discrete tissue types and specific disease states have positioned microRNAs as promising new biomarkers for diagnostic application in cancer. We have applied Exiqons highly sensitive LNA™-based qPCR platform for detection of microRNAs, which has enabled microRNA profiling in biofluids where levels are extremely low. The platform uses a single RT reaction to conduct full miRNome profiling and allows high-throughput profiling of microRNAs without the need for pre-amplification. Thousands of biofluid samples including serum/plasma and urine have been profiled to determine normal reference ranges for circulating microRNAs as well as to identify biomarkers of disease. Extensive data qualification and analysis methods have been developed and are central parameters to secure high quality data from biofluids. The methods can quickly and robustly be applied in biomarker discovery and validation projects. We will present examples from our collaborative cancer diagnostic projects. Also we have developed a new exosome enrichment method and will present a comparison of microRNA profiles obtained with this method to profiles obtained with different commercial available exosome isolation methods and standard profiles of whole plasma and serum. Citation Format: Thorarinn Blondal, Anni Thomsen, Jorg Krummheyer, Peter Mouritzen, Ditte Andreasen, Maria Theilum, Jan Stenvang, Claus L. Andersen, Hans J. Nielsen, Nils Brunner. MicroRNA in biofluid as robust biomarkers for cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5233. doi:10.1158/1538-7445.AM2014-5233

MicroRNA in biofluids—Robust biomarkers for disease, toxicology, or injury studies: The case of minimally invasive colorectal cancer detection.

20 Background: MicroRNAs function as post-transcriptional regulators of gene expression. Their high relative stability in common clinical source materials (FFPE blocks, plasma, serum, urine, saliva, etc.) and the ability of microRNA expression profiles to accurately classify discrete tissue types and specific disease states have positioned microRNAs as promising new biomarkers for diagnostic application. Furthermore microRNAs have been shown to be rapidly released from tissues into the circulation with the development of pathology. METHODS Thousands of biofluid samples were profiled including blood derived plasma/serum and urine using a genome-wide LNA-based microRNA qPCR platform, which has unparalleled sensitivity and robustness even in biofluids with extremely low microRNA levels. Only a single RT reaction is required to conduct full miRNome profiling thereby facilitating high-throughput profiling without the need for pre-amplification. RESULTS Normal reference ranges for circulating microRNAs were determined in several biofluids, allowing development of qPCR arrays containing only relevant microRNA subsets present in various biofluids together with tissue specific microRNA markers. Procedures were developed to control pre-analytical variables, for quality checking and qualifying biofluid samples in particular serum and plasma but also urine and other biofluids. An extensive QC system was implemented in order to secure technical excellence and reveal any unwanted bias in the dataset. We currently screen and validate microRNAs biomarkers for cancer with the aim of developing minimal invasive tests to be applied in early detection population screens. CONCLUSIONS The qPCR panels support development of robust biomarkers in disease, toxicology, and injury studies. We will demonstrate how panels may be quickly and robustly applied in biomarker discovery/validation projects using the specific case early detection of colorectal cancer in blood. Close attention is required on pre-analytical parameters. Hemolysis and cellular contamination affect miRNA profiles in biofluids and control is required.