EPCO-21. THE SPATIAL ORGANIZATION OF H3-K27M MUTANT DIFFUSE MIDLINE GLIOMA

Histone 3 lysine27-to-methionine mutant diffuse midline gliomas (H3-K27M DMGs) are among the most lethal brain tumors. Their putative cellular hierarchy has been shown to be driven by self-renewing stem-like cells arrested in an oligodendrocyte precursor-like (OPC-like) state, of which few cells are able to differentiate towards more mature astrocyte (AC)-like and oligodendrocyte (OC)-like cells. However, the spatial organization underlying this tumor cell architecture and its microenvironmental interactions in intact H3-K27M DMG tissues remain unknown. Here, we profiled the single cell transcriptomes of 45 patient H3-K27M DMGs and derived cell population-specific marker gene combinations to characterize the single cell spatial organization of 16 tumors using targeted in situ sequencing. We thereby resolved different malignant and non-malignant cell populations including cycling, OPC-like, AC-like, OC-like, mesenchymal tumor cells, and non-malignant oligodendrocytes, astrocytes, neurons, myeloid cells, T cells, and vascular cells directly in situ. Global neighborhood analyses indicate a higher tendency of cycling OPC-like cells, vascular cells, and neurons to localize within a more restricted homogeneous compartment, whereas AC-like cells, non-malignant astrocytes and myeloid cells tend to intermingle with different cell populations in a more diffuse manner. Among malignant cells, we observed cycling OPC-like and OC-like cells to co-localize within a niche-like structure that is surrounded by more differentiated AC-like cells. We further validated this stem-like niche at the protein level using multiplexed immunofluorescence via the CODEX system. Finally, we characterized relationships between malignant and non-malignant cells, consistently identifying preferred neighborhoods of mesenchymal tumor cells with vascular and myeloid cells. Together, this study resolves the spatial architecture of H3-K27M DMG malignant and non-malignant cells at single cell resolution and identifies a local niche of the oligodendroglial lineage containing the OPC-like cancer stem-like cells, thus providing novel insights into the cancer stem-like compartment in H3-K27M DMGs and suggesting potential avenues for its perturbation.

PATH-02. ANALYSIS OF MICRORNA EXPRESSION IN BRAIN METASTASES USING NEXT-GENERATION SEQUENCING

BACKGROUND

Brain metastases (BMs) are intracranial tumors that frequently occur in adult cancer patients. Because the prognosis of patients with BM individually varies, it would be useful to improve prognostic scoring tools by including new high-performance biomarkers. MicroRNAs (miRNAs) appear to be promising in this regard as they are highly stable and, thus, suitable for both next-generation sequencing (RNA-Seq) and retrospective analyses in formalin-fixed and paraffin-embedded (FFPE) tissues.Material and

METHODS

Total RNA enriched for miRNAs was isolated from 71 freshly frozen histopathologically confirmed BMs with origin in 5 tumor types (ca lung - 37%, melanoma - 23%, ca breast - 18%, RCC - 15%, CRC - 7%) using mirVana miRNA Isolation Kit (Thermo Fisher Scientific). Sequencing libraries were prepared from RNA using the QIAseq miRNA Library Kit (Qiagen) and sequenced using the NextSeq 500 platform (Illumina). The miRNA molecules were subsequently transcribed from total RNA samples isolated from a retrospective set of 119 FFPE tissues using the TaqMan Advanced miRNA cDNA Synthesis Kit, and the expression of selected miRNAs was validated in a pilot experiment by qPCR using TaqMan Fast Advanced Master Mix and appropriate TaqMan MicroRNA Assays (all from Thermo Fisher Scientific).

RESULTS

The differential analysis identified 373 miRNAs with significantly different expression among the 5 BMs groups (p< 0.001). A molecular classifier based on the expression of 32 miRNAs was able to classify all samples correctly. Out of these, seven, including miR-122-5p, miR-141-3p, miR-146a-5p, miR-194-5p, miR-200c-3p, miR-211-3p, and miR-215-5p, were chosen for subsequent validation and their significantly different expression in 5 BMs groups was validated.

CONCLUSIONS

Presented results confirm the importance of studying dysregulated miRNA expression in BM and the diagnostic potential of validated miRNAs. The study was prepared with the grant support of the Ministry of Health of the Czech Republic - grant No. NV18-03-00398.

CCRG-03. STUDY OF PIWI-INTERACTING RNAS IN GLIOBLASTOMA PATHOLOGY: A NEW LEVEL OF REGULATION OF GLIOBLASTOMA STEM CELLS?

BACKGROUND

One of the putative mechanisms of early recurrence of GBM is the existence of glioblastoma stem cells (GSCs) that can resist therapy and subsequently establish new GBM foci. PIWI-interacting RNAs (piRNAs), responsible for maintaining genome stability, may then play a key role in their biology, particularly in germ and stem cells. A number of piRNA molecules are also promising biomarkers useful for prognosis and prediction of disease progression.Material and

METHODS

Glioblastoma stem cells were cultured in DMEM/F12 medium supplemented with bFGF and EGF growth factors. DMEM medium containing 10% fetal bovine serum (FBS) was used to culture differentiated cells. RNA was isolated from the selected paired primocultures and subsequently checked for quality by capillary electrophoresis. NEBNext Small RNA Library Prep Set was used for the preparation of cDNA libraries. Sequencing analysis was performed using the Next500/550 High Output v2 Kit for 75 cycles and the NextSeq500 sequencer.

RESULTS

Twenty paired primary cultures were prepared to verify the expression of CD133 and SOX2 in GSCs, the ability to establish tumors in immunodeficient mice, and the ability to differentiate. At this time, we finished sequencing of piRNA molecules and acquired data are bioinformatically analysed. Subsequently, we will perform analysis of selected piRNAs to be diagnostic and prognostic biomarkers on the GBM samples and non-tumor brain controls. All results will be presented at the conference.

CONCLUSION

Based on recent studies, it is evident that piRNA expression can have a significant impact on GBM biology. Their expression within GSCs may then provide a tool for identifying and targeting these cells and could be usable as a diagnostic and prognostic biomarker in GBM patients.The study was supported by the programme project of the Ministry of Health of the Czech Republic with reg. no. NV19-03-00501, NV19-03-00559, Conceptual development of research organization FNBr, 65269705

BIOM-53. SPECIFIC MICRORNA EXPRESSION PATTERN PREDICTS RECURRENCE IN ATYPICAL MENINGIOMA

Meningiomas are the most common primary tumors of the central nervous system (CNS). Atypical meningioma (AM) recurs in 40% of patients despite total resection and radiotherapy (RT). No consensus on optimal adjuvant management was found, and it is difficult to identify patients insensitive to RT in real-life clinical practice. A promising group of biomarkers represent microRNAs (miRNAs), short non-coding RNAs that regulate most biological processes, including cell proliferation, differentiation, and apoptosis. The study aims to identify tissue miRNAs capable of predicting patients with AM who could benefit from the indicated adjuvant RT. The study includes 80 patients with AM in the exploratory phase and 400 patients with meningioma in the validation phase. Total RNA enriched with miRNAs was isolated from FFPE tissue using the mirVana miRNA Isolation Kit (TF Scientific). Subsequently, RNA quantity and quality controls were measured using NanoDrop 2000 (TF Scientific) and Qubit 2.0 (TF Scientific) instruments. A global miRNA expression profile was generated using the TaqMan Array Human MicroRNA Cards (TF Scientific), which allow the detection of up to 754 miRNAs simultaneously. Obtained data were processed and integrated through bioinformatics algorithms with clinicopathological data of patients with AM.The study identified significantly dysregulated miRNAs among AM patients with and without recurrence (p < 0.05). Results also suggest dysregulated miRNA expression profile in AM patients with indicated RT who did/did not develop a recurrence (p < 0.05). Lists of individual miRNAs and detailed graphical analyses will be included in the conference presentation.The results will help predict the prognosis of surgically intervened patients more accurately and can help determine which patients will benefit from the adjuvant RT. This research is supported by the AZV grant from the Ministry of Health of the Czech Republic (reg. No. NV19-03-00559) and Conceptual development of research organization (FNBr, 65269705). All rights reserved.

P12.10.A Supratentorial glioblastoma with spinal metastasis: a case report with molecular profiling

Background

Glioblastoma (GBM) is regarded as an aggressive brain tumor that rarely develops extracranial metastases. Despite well-investigated molecular alterations in GBM, there is a limited understanding of these associated with the metastatic potential of GBM.

Material and Methods

We present a case report of a 43-year-old woman with frontal GBM IDH-wildtype, who underwent gross-total resection followed by chemoradiation. Five months after surgery, the patient was diagnosed with an intraspinal GBM metastasis. Next-generation sequencing analysis of both primary and metastatic GBM tissues was performed using the Illumina TruSight Tumor 170 assay.

Results

The number of single nucleotide variants observed in the metastatic sample was more than 2-times higher. Mutations in TP53, PTEN, and RB1 found in the primary and metastatic tissue samples are indicative of the mesenchymal GBM subtype. Among others, in the metastatic sample, there were detected two inactivating mutations (Arg1026Ile, Trp1831Ter) in the NF1 gene, two novel NOTCH3 variants of unknown significance predicted to be damaging (Pro1505Thr, Cys1099Tyr), one novel ARID1A variant of unknown significance (Arg1046Ser), and one gene fusion of unknown significance EIF2B5-KIF5B.

Conclusion

Based on the literature evidence, the inactivation of NF1, NOTCH3, and ARID1A could explain, at least in part, the acquired invasiveness and metastatic potential in this particular GBM case.

This work was supported by the grant MUNI/A/1408/2021 of the Masaryk University, Brno, Czech Republic, and INTER-EXCELLENCE Programme / INTER-COST project no. LTC20027 of the Ministry of Health, Czech Republic.

JS04.6.A The landscape of tumor cell states and spatial organization in H3-K27M mutant diffuse midline glioma across age and location

Background

Histone 3 lysine27-to-methionine mutations (H3-K27M) frequently occur in childhood diffuse midline gliomas (DMGs) of the pons, thalamus and spinal cord, presumed to be driven by the specific spatiotemporal context of these midline locations during postnatal development. While most common in the pons and at mid-childhood ages, the same oncohistone mutation is recurrently detected in adult DMGs and throughout different midline regions. The potential heterogeneity of tumors at different ages and in different anatomical locations of the midline are vastly understudied.

Material and Methods

Through dissecting the transcriptomic, epigenomic and spatial architectures of a comprehensive cohort of patient H3-K27M DMGs - spanning the age range from 2-68 years and locations from spinal cord to thalamus - at single cell resolution, we delineate how age- and location-dependent contexts shape glioma cell-intrinsic and -extrinsic features in light of the shared driver mutation.

Results

We identify that oligodendrocyte precursor (OPC)-like cells constitute the stem-like compartment in H3-K27M DMGs across all clinico-anatomical groups, however, depending on location, display varying levels of maturity resembling less differentiated pre-OPCs or more mature OPCs further differentiated along the oligodendroglial lineage. We further demonstrate increased mesenchymal cell states in adult tumors, which we link to age-related differences in glioma-associated immune cell compartments. We for the first time resolve the spatial organization of H3-K27M DMG cell types in intact patient tissues, identifying a local niche of the oligodendroglial lineage.

Conclusion

Our study provides a powerful resource for rational modeling and therapeutic frameworks taking into account determinants of age and location in this lethal glioma group.

The Significance of MicroRNAs in the Molecular Pathology of Brain Metastases

Brain metastases are the most frequent intracranial tumors in adults and the cause of death in almost one-fourth of cases. The incidence of brain metastases is steadily increasing. The main reason for this increase could be the introduction of new and more efficient therapeutic strategies that lead to longer survival but, at the same time, cause a higher risk of brain parenchyma infiltration. In addition, the advances in imaging methodology, which provide earlier identification of brain metastases, may also be a reason for the higher recorded number of patients with these tumors. Metastasis is a complex biological process that is still largely unexplored, influenced by many factors and involving many molecules. A deeper understanding of the process will allow the discovery of more effective diagnostic and therapeutic approaches that could improve the quality and length of patient survival. Recent studies have shown that microRNAs (miRNAs) are essential molecules that are involved in specific steps of the metastatic cascade. MiRNAs are endogenously expressed small non-coding RNAs that act as post-transcriptional regulators of gene expression and thus regulate most cellular processes. The dysregulation of these molecules has been implicated in many cancers, including brain metastases. Therefore, miRNAs represent promising diagnostic molecules and therapeutic targets in brain metastases. This review summarizes the current knowledge on the importance of miRNAs in brain metastasis, focusing on their involvement in the metastatic cascade and their potential clinical implications.

Abstract 76: Comprehensive genomic profiling as an approach to guide therapeutic planning in pediatric patients with high-risk solid tumors

Despite the great achievements in treating pediatric cancer patients in the last several decades, approximately one fifth of patients remains uncurable using standard therapeutic modalities and require search for innovative therapeutic approaches. Advances in sequencing techniques and bioinformatic data processing enabled identification of wide spectrum of molecular alterations including single nucleotide variants, copy number aberrations, fusion genes or changes in expression and methylation patterns, which could serve as therapeutic targets. Translation of comprehensive molecular profiling into clinical practice is still limited, however, multiple precision oncology initiatives have already explored feasibility of this approach.

From September 2016 to December 2020, a total of 160 patients with high-risk solid tumors that were treated or consulted at Department of Pediatric Oncology of University Hospital Brno were subjected to molecular analysis of tumor tissue using whole-exome sequencing, targeted RNA sequencing, whole-transcriptome profiling and array-CGH. In 18 patients, 2 or more biopsies were analyzed due to relapse or progression of the disease. In the cohort, CNS tumors were the most prevalent (41%), followed by sarcomas (33%) and neuroblastoma (9%). All patients were presented at multidisciplinary molecular tumor board, where treatment recommendations were discussed.

In 37% of patients (n = 59), therapeutic targets were identified. Most commonly identified targets included BRAF (n = 9), FGFR1 (n = 7), NF1 (n = 6), NRAS (n = 5) and PIK3CA (n = 4), making RAS/MAPK signaling most frequently altered pathway in the subgroup. Single nucleotide variants or small indels accounted for 65% of actionable findings, followed by fusion genes (12%), copy number aberrations (9%), CD274 expression (7%, confirmed by IHC staining for PD-L1 protein), and high tumor mutational burden (7%). Clinically relevant fusions were found in 25% of patients and 20% of identified fusions were targetable. 8 patients were eligible for immunotherapy based on either PD-L1 expression, or high tumor mutational burden (>10 mut/Mb).

Using molecular-based approach in treating high-risk patients represents a promising strategy and helps to understand the complexity of pediatric malignancies though examining tumor biology at multiple levels. Implementing the concept of precision oncology into clinical practice could not only be beneficial in the context of chances for improved survival of high-risk patients, but might also be convenient for other patients, whose successful treatment comes at cost of various secondary complications due to intensive chemotherapy/radiotherapy approaches.

Supported by Ministry of Health of the Czech Republic, grant nr. NV19-03-00562, NV19-03-00501, NV19-03-00559 and NU20-03-00240. All rights reserved.

Citation Format: Petra Pokorna, Hana Palova, Tina Catela Ivkovic, Sona Adamcova, Michal Kyr, Vojtech Bystry, Robin Jugas, Karolina Trachtova, Dagmar Al Tukmachi, Tomas Merta, Jaroslav Juracek, Jiri Sana, Sona Mejstrikova, Marta Jezova, Peter Mudry, Zdenek Pavelka, Jaroslav Sterba, Ondrej Slaby. Comprehensive genomic profiling as an approach to guide therapeutic planning in pediatric patients with high-risk solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 76.

Abstract 908: Small RNA-seq analysis of PIWI-interacting RNAs in glioblastoma stem cells: Identification of new therapeutic targets in glioblastoma patients

Introduction: Glioblastoma (GBM) is the most common malignancy affecting the CNS. Despite radical therapy, recurrence of GBM is a frequent and relatively early event in the course of the disease. One of the putative mechanisms of early recurrence of GBM is the existence of glioblastoma stem cells (GSCs) that can resist therapy and subsequently establish new GBM foci. PIWI-interacting RNAs (piRNAs), responsible for maintaining genome stability, may play a key role not only in the biology of germ and stem cells but also GSCs since their dysregulated expression has been described in several cancers, including GBM. Thus, the identification of specific piRNAs in GSCs could allow the distinction of these cells from other GBM cells and their eventual targeting. Some piRNAs could also be promising biomarkers useful for prognosis and prediction of disease progression.

Material and Methods: Native GBM tissues dissociated using the Papain Dissociation System were used for culturing of paired cell primary cultures. Cells were divided into two aliquots with different culture conditions. GSCs were cultured in DMEM/F12 medium supplemented with bFGF and EGF growth factors. DMEM medium containing 10% fetal bovine serum (FBS) was used to culture non-stem GBM cells. Subsequently, the presence of neural stem cell markers CD133 and SOX2, the ability of GSCs to establish tumors in immunodeficient mice, and the ability to differentiate into more mature cell types were analyzed. RNA isolated from the paired primary cultures was used for small-RNA sequencing (RNA-seq). QIAseq miRNA Library Kit was used for the preparation of cDNA libraries. Sequencing analysis was performed using the NextSeq 500/550 High Output v2 Kit (75 cycles) and the NextSeq 500 sequencer.

Results: Twelve paired primary cultures were prepared to global piRNA expression profiling. Small RNA-seq bioinformatics analysis identified between 3.45 and 5.51% of unique mapped piRNA reads in all samples; GSCs expressing higher levels of piRNA molecules in comparison with paired GBM cells. Subsequently, we identified a set of significantly differentially expressed piRNAs in GSCs. Expression of selected piRNAs was then artificially regulated in primary GSCs in vitro, and the effect of these molecules on neurosphere formation, viability, and cell genome stability was analyzed. Finally, we also observed an association of piR-23231 with overall survival of GBM patients. All results will be presented at the AACR Annual Meeting 2022.

Conclusion: Based on the results so far, piRNAs seem to play an important role in GSCs as well as GBM biology and their targeting may be a promising tool for therapy of GBM patients. The study was supported by the programme project of the Ministry of Health of the Czech Republic with reg. no. NV19-03-00501 and NV19-03-00559.

Citation Format: Jiri Sana, Frantisek Siegl, Marek Vecera, Pavel Fadrus, Jaroslav Juracek, Petra Pokorna, Karolina Trachtova, Tomas Kazda, Ondrej Slaby. Small RNA-seq analysis of PIWI-interacting RNAs in glioblastoma stem cells: Identification of new therapeutic targets in glioblastoma patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 908.

Abstract 2802: Molecular and functional characterization of colorectal cancer derived-exosomes and exosomal coding and long non-coding RNA

Colorectal cancer (CRC) accounts for 9.7% of all cancers which makes it one of the three most commonly diagnosed cancer types worldwide. Prognosis of the patients with CRC depends mainly on the extent of the disease at the time of diagnosis. Therefore, the early detection of CRC and precancerous lesions is one of the main requirements of successful treatment. In recent years exosomes emerged as potential reservoirs of clinically useful biomarkers. Exosomes are 30-150 nm sized membranous vesicles that are endogenously produced by almost all cell types. They participate in intercellular communication by delivering proteins, microRNAs (miRNAs), mRNAs or long non-coding RNAs (lncRNAs) to recipient cells. In the context of cancer, intercellular communication allows cancer cells to create a favorable microenvironment for their growth. It has been shown that cancer-derived exosomes promote pathways contributing to hallmarks of cancer.To investigate diagnostic potential of exosomal RNA in CRC, blood serum samples were collected from patients with CRC and age- and sex-matched controls. Exosome isolation protocol was optimized, and the presence of vesicles in the exosome size range was confirmed using both dynamic light scattering (DLS) analysis as well as electron microscopy (TEM). Downstream analysis of serum exosomal RNA using next-generation sequencing (Illumina NextSeq 550) from exploratory cohort of CRC samples (N=50) and healthy controls (N=20) revealed both coding and non-coding RNAs to be differentially expressed (FC>1.5, p-value < 0.01). Among these were genes already reported to be dysregulated in CRC such as GAS5, but also lncRNAs previously unreported in CRC exosomes (AC103760.1, LINC02709 or PGBP) were identified.

Gene set enrichment analysis (GSEA) was used to link RNAs identified within exosomes to their molecular functions. Using the Hallmark gene sets (MsigDB) as a reference, we discovered high enrichment of genes related to MYC targets, E2F targets and G2M checkpoint in healthy controls compared to CRC samples. All three hallmarks comprise genes crucial for cell proliferation. The first results indicated that the exosomal RNAs could be promising candidates as new diagnostic biomarkers in CRC, although further in vitro and in vivo exploration of identified differentially expressed lncRNAs is necessary. This work was supported by Ministry of Health of the Czech Republic grant nr. NU20-03-00127, NV19-03-00501 and NV19-03-00559. All rights reserved.

Citation Format: Tina Catela Ivkovic, Marie Mądrzyk, Karolina Trachtova, Petra Faltejskova-Vychytilova, Tana Machackova, Petra Pokorna, Jaroslav Juracek, Jiri Sana, Ondrej Slaby. Molecular and functional characterization of colorectal cancer derived-exosomes and exosomal coding and long non-coding RNA [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2802.

microRNAs as the predictors for atrial fibrillation recurrence after catheter ablation: next-generation sequencing study

Funding Acknowledgements

Type of funding sources: Public hospital(s). Main funding source(s): This study was supported by Specific research of the Masaryk University (MUNI/A/1156/2021) and Institutional support project of St. Anne’s University hospital in Brno.

Background

Atrial fibrillation (AF) represents the most common arrhythmia. Catheter ablation (CA) of AF is indicated in patients with recurrent and symptomatic AF episodes fulfilling the criteria stated in the current guidelines. Despite the strict inclusion/exclusion criteria, AF recurrence after CA remains notably high. Thus, identifying a novel marker to more precisely select individuals that will profit from CA would be beneficial. microRNAs, i.e., small non-coding RNAs of the length of approx. 22 nucleotides are known to play crucial roles in the pathophysiology of AF and therefore represent promising biomarkers in the field.

Purpose

Aim of the study was to identify potential plasmatic microRNAs as novel biomarkers for predicting AF recurrence after CA.

Methods

Prospective monocentric and biomarker-screening study. Altogether 49 consecutive AF patients indicated for CA were enrolled. Before the CA, blood sampling was performed, and plasma was isolated. All patients then underwent CA and were followed up for 6 months. Within the close-up visit at the 6th month, 24-hour ECG Holter monitoring was performed to evaluate participants’ rhythm. For the next-generation sequencing (NGS), 5 patients with recurrent AF and 5 age- and BMI-matching patients without recurrent AF were randomly selected from the baseline cohort. NGS was performed using Illumina Instrument, and obtained data were then evaluated using edgeR and DESeq2 algorithms to identify all miRNAs present in the study samples. Filtering was performed to exclude microRNAs with low expression (i.e., base mean value at least 20 and more and expression detectable in all study samples). Comparison of the two groups (with and without AF recurrence) was performed using standard statistical tests with correction for multiple comparisons: differences with log2 fold change above 0,5 or below -0,5 with p < 0,05 were considered biologically and statistically significant.

Results

In total, 2069 various microRNAs were identified. Altogether 59 microRNAs statistically significantly differed between the groups. The most altered microRNAs were as follows: miR-29c-5p, miR-183-5p, miR-190b, miR-206, miR-326, miR-505-5p, miR-548b, miR-574-3p, miR-1294 and miR-1296-5p.

Conclusion

Using NGS, we have identified 59 potential microRNAs whose plasmatic levels are altered between individuals with and without early AF recurrence. If the results are confirmed on the larger patients’ cohort, these microRNAs will represent supportive biomarkers to identify AF patients benefiting from CA.

LncRNA PVT1 is increased in renal cell carcinoma and affects viability and migration in vitro

Background

Renal cell carcinoma is difficult to diagnose and unpredictable in disease course and severity. There are no specific biomarkers for diagnosis and prognosis estimation feasible in clinical practice. Long non‐coding RNAs (lncRNAs) have emerged as potent regulators of gene expression in recent years. Aside from their cellular role, their expression patterns could be used as a biomarker of ongoing pathology.

Methods

In this work, we used next‐generation sequencing for global lncRNA expression profiling in tumor and non‐tumor tissue of RCC patients. The four candidate lncRNAs have been further validated on an independent cohort. PVT1, as the most promising lncRNA, has also been studied using functional in vitro tests.

Results

Next‐generation sequencing showed significant dysregulation of 1163 lncRNAs; among them top 20 dysregulated lncRNAs were AC061975.7, AC124017.1, AP000696.1, AC148477.4, LINC02437, GATA3‐AS, LINC01762, LINC01230, LINC01271, LINC01187, LINC00472, AC007849.1, LINC00982, LINC01543, AL031710.1, and AC019197.1 as down‐regulated lncRNAs; and SLC16A1‐AS1, PVT1, LINC0887, and LUCAT1 as up‐regulated lncRNAs. We observed statistically significant dysregulation of PVT1, LUCAT1, and LINC00982. Moreover, we studied the effect of artificial PVT1 decrease in renal cell line 786–0 and observed an effect on cell viability and migration.

Conclusion

Our results show not only the diagnostic but also the therapeutic potential of PVT1 in renal cell carcinoma.

HLA-E and HLA-F Are Overexpressed in Glioblastoma and HLA-E Increased After Exposure to Ionizing Radiation

BACKGROUND/AIM

Glioblastoma (GBM) is one of the deadliest human cancers responding very poorly to therapy. Although the central nervous system has been traditionally considered an immunologically privileged site with an enhanced immune response, GBM appears to benefit from this immunosuppressive milieu. Immunomodulatory molecules play an important role in immune tumor-host interactions. Non-classical human leukocyte antigens (HLA) class Ib molecules HLA-E, HLA-F, and HLA-G have been previously described to be involved in protecting semi-allogeneic fetal allografts from the maternal immune response and in transplant tolerance as well as tumoral immune escape. Unfortunately, their role in GBM remains poorly understood. Our study, therefore, aimed to characterize the relationship between the expression of these molecules in GBM on the transcriptional level and clinicopathological and molecular features of GBM as well as the effect of ionizing radiation.

MATERIALS AND METHODS

We performed the analysis of HLA-E, HLA-F, and HLA-G mRNA expression in 69 GBM tissue samples and 21 non-tumor brain tissue samples (controls) by reverse transcription polymerase chain reaction. Furthermore, two primary GBM cell cultures had been irradiated to identify the effect of ionizing radiation on the expression of non-classical HLA molecules.

RESULTS

Analyses revealed that both HLA-E and HLA-F are significantly up-regulated in GBM samples. Subsequent survival analysis showed a significant association between low expression of HLA-E and shorter survival of GBM patients. The dysregulated expression of both molecules was also observed between patients with methylated and unmethylated O-6-methylguanine-DNA methyltransferase (MGMT) promoter. Finally, we showed that ionizing radiation increased HLA-E expression level in GBM cells in vitro.

CONCLUSION

HLA-E and HLA-F play an important role in GBM biology and could be used as diagnostic biomarkers, and in the case of HLA-E also as a prognostic biomarker.

MicroRNA as an Early Biomarker of Neonatal Sepsis

Sepsis is a major cause of lethality in neonatal intensive care units. Despite significant advances in neonatal care and growing scientific knowledge about the disease, 4 of every 10 infants born in developed countries and suffering from sepsis die or experience considerable disability, including substantial and permanent neurodevelopmental impairment. Pharmacological treatment strategies for neonatal sepsis remain limited and mainly based upon early initiation of antibiotics and supportive treatment. In this context, numerous clinical and serum-based markers have been evaluated for diagnosing sepsis and evaluating its severity and etiology. MicroRNAs (miRNAs) do not encode for proteins but regulate gene expression by inhibiting the translation or transcription of their target mRNAs. Recently, it was demonstrated in adult patients that miRNAs are released into the circulation and that the spectrum of circulating miRNAs is altered during various pathologic conditions, such as inflammation, infection, and sepsis. Here, we summarize current findings on the role of circulating miRNAs in the diagnosis and staging of neonatal sepsis. The conclusions point to substantial diagnostic potential, and several miRNAs have been validated independently by different teams, namely miR-16a, miR-16, miR-96-5p, miR-141, miR-181a, and miR-1184.

PATH-01. SMALL RNASEQ ANALYSIS OF MICRORNAS IN BRAIN METASTASIS

MicroRNAs (miRNAs) are a well-known subclass of short non-coding RNAs responsible for posttranscriptional gene silencing and have been described as dysregulated in many cancers. They have also been shown to be both specific diagnostic, prognostic, and predictive biomarkers as well as therapeutic targets. Therefore, specific miRNA expression patterns of BMs of various origins could serve as a promising diagnostic tool for determining both the original tumor and the prognosis in patients with BMs of unknown origin. For identifying significantly dysregulated miRNAs among BMs (n=90) with various origin and non-tumor brain tissues (n=12), small RNAseq analyses were used. cDNA libraries were prepared using QIAseq miRNA Library Kit and purified by Qiaseq beads. The final sequencing analyses were performed by Next 500/550 High Output v2 Kit-75 cycles using the NextSeq 500 instrument. For miRNA mapping and analysis, Miraligner and MirBase were used. Bioinformatic analysis of obtained sequencing data identified 472 significantly dysregulated miRNAs (logFc >2, adj.p-value< 0.05) between BM and non-tumor samples. The comparison of BMs origin from lung BMs (n = 26) with other BMs revealed 132 significantly dysregulated miRNAs, mainly miR-4662a-5p, miR-1179, miR-211-5p, miR-146a-5p, and miR-194-5p. The most significantly dysregulated miRNAs in breast BMs were miR-4728-3p, miR-211-5p, miR-184, miR-365b-5p, and miR-2115-3p. In BMs originating from melanoma, miR-200c-3p, miR-141-5p, miR-200b-5p, miR-514a-3p, and miR-200b-3p showed the most aberrant expression. We have demonstrated that miRNA profiling could be a potent tool for the partition of brain metastases based on their origin. We found that miRNA signatures corresponding to particular origins are rather distinct from the profiles of the rest of BMs. Our results suggest that after validation, miRNA profiling can be used to identify the origin of brain metastases and potentially for the refinement of the diagnosis. Supported by the Ministry of Health of the Czech Republic, grant nr. NV18-03-00398.

MicroRNAs in the development of resistance to antiseizure drugs and their potential as biomarkers in pharmacoresistant epilepsy

Although many new antiseizure drugs have been developed in the past decade, approximately 30%-40% of patients remain pharmacoresistant. There are no clinical tools or guidelines for predicting therapeutic response in individual patients, leaving them no choice other than to try all antiseizure drugs available as they suffer debilitating seizures with no relief. The discovery of predictive biomarkers and early identification of pharmacoresistant patients is of the highest priority in this group. MicroRNAs (miRNAs), a class of short noncoding RNAs negatively regulating gene expression, have emerged in recent years in epilepsy, following a broader trend of their exploitation as biomarkers of various complex human diseases. We performed a systematic search of the PubMed database for original research articles focused on miRNA expression level profiling in patients with drug-resistant epilepsy or drug-resistant precilinical models and cell cultures. In this review, we summarize 17 publications concerning miRNAs as potential new biomarkers of resistance to antiseizure drugs and their potential role in the development of drug resistance or epilepsy. Although numerous knowledge gaps need to be filled and reviewed, and articles share some study design pitfalls, several miRNAs dysregulated in brain tissue and blood serum were identified independently by more than one paper. These results suggest a unique opportunity for disease monitoring and personalized therapeutic management in the future.

Small RNA Sequencing Identifies PIWI-Interacting RNAs Deregulated in Glioblastoma-piR-9491 and piR-12488 Reduce Tumor Cell Colonies In Vitro

Glioblastoma (GBM) is the most frequently occurring primary malignant brain tumor of astrocytic origin. To change poor prognosis, it is necessary to deeply understand the molecular mechanisms of gliomagenesis and identify new potential biomarkers and therapeutic targets. PIWI-interacting RNAs (piRNAs) help in maintaining genome stability, and their deregulation has already been observed in many tumors. Recent studies suggest that these molecules could also play an important role in the glioma biology. To determine GBM-associated piRNAs, we performed small RNA sequencing analysis in the discovery set of 19 GBM and 11 non-tumor brain samples followed by TaqMan qRT-PCR analyses in the independent set of 77 GBM and 23 non-tumor patients. Obtained data were subsequently bioinformatically analyzed. Small RNA sequencing revealed 58 significantly deregulated piRNA molecules in GBM samples in comparison with non-tumor brain tissues. Deregulation of piR-1849, piR-9491, piR-12487, and piR-12488 was successfully confirmed in the independent groups of patients and controls (all p < 0.0001), and piR-9491 and piR-12488 reduced GBM cells’ ability to form colonies in vitro. In addition, piR-23231 was significantly associated with the overall survival of the GBM patients treated with Stupp regimen (p = 0.007). Our results suggest that piRNAs could be a novel promising diagnostic and prognostic biomarker in GBM potentially playing important roles in gliomagenesis.

BSCI-01. Small RNAseq analysis of microRNAs in brain metastasis

MicroRNAs (miRNAs) are a well-known subclass of short non-coding RNAs responsible for posttranscriptional gene silencing and have been described as dysregulated in many cancers. They have also been shown to be both specific diagnostic, prognostic, and predictive biomarkers as well as therapeutic targets. Therefore, specific miRNA expression patterns of BMs of various origins could serve as a promising diagnostic tool for determining both the original tumor and the prognosis in patients with BMs of unknown origin.

For identifying significantly dysregulated miRNAs among BMs (n = 90) with various origin and non-tumor brain tissues (n = 12), small RNAseq analyses were used. cDNA libraries were prepared using QIAseq miRNA Library Kit and purified by Qiaseq beads. The final sequencing analyses were performed by Next 500/550 High Output v2 Kit-75 cycles using the NextSeq 500 instrument. For miRNA mapping and analysis, Miraligner and MirBase were used.

Bioinformatic analysis of obtained sequencing data identified 472 significantly dysregulated miRNAs (logFc>2, adj.p-value<0.05) between BM and non-tumor samples. The comparison of BMs origin from lung BMs (n = 26) with other BMs revealed 132 significantly dysregulated miRNAs, mainly miR-4662a-5p, miR-1179, miR-211-5p, miR-146a-5p, and miR-194-5p. The most significantly dysregulated miRNAs in breast BMs were miR-4728-3p, miR-211-5p, miR-184, miR-365b-5p, and miR-2115-3p. In BMs originating from melanoma, miR-200c-3p, miR-141-5p, miR-200b-5p, miR-514a-3p, and miR-200b-3p showed the most aberrant expression.

We have demonstrated that miRNA profiling could be a potent tool for the partition of brain metastases based on their origin. We found that miRNA signatures corresponding to particular origins are rather distinct from the profiles of the rest of BMs. Our results suggest that after validation, miRNA profiling can be used to identify the origin of brain metastases and potentially for the refinement of the diagnosis.

Supported by the Ministry of Health of the Czech Republic, grant nr. NV18-03-00398.

P–275 Development of a prediction model using machine learning on small noncoding RNA biomarkers for non-invasive selection of high-quality embryos for the in vitro fertilization process

Study question

The aim of the study was to identify molecules in the embryo culture medium as important predictive biomarkers of high-quality embryos

Summary answer

The study identified 14 canonical iso-miRNA molecules that prognostically determine the quality of the embryo with a prediction accuracy with 95% sensitivity and 80% specificity.

What is known already

The quality of the embryo for the success of the IVF process is not specifically diagnosed, only morphological features (monitoring in the embryoscope) are considered. Embryo quality selection systems have likely reached their peak. The success rate of the IVF process is only 29%.; it is therefore necessary to look for other biomarkers. The oocyte itself can significantly predict the development of the early embryo,as it is a supplier of RNA and cellular mechanisms. However, collection follicular fluid is technically demanding. The probability of oocyte fertilization does not reach the required percentage therefore other embryological techniques multiply the economic costs.

Study design, size, duration

Women (n = 734) who visited the IVF centre were recruited for the study. Oocytes were collected from 54 of them and used for IVF. After 4/5-day embryo cultivation, the best quality embryo was selected and used for implantation into the uterus. The culture medium has been collected from 60 embryos during 3 years (2018–2020). Written informed consent was obtained from all patients. The study has been approved by the Ethical committee of the Košice governing region

Participants/materials, setting, methods

We used fresh/frozen culture media of embryos selected using an embryoscope. Further, information regarding the success of IVF, pregnancy and IVF failure was collected. Culture media libraries of noncoding small RNAs (miRNAs) were examined using massively parallel sequencing on the Illumina platform. Obtained data was processed with freely available bioinformatic tools and machine learning. For methods with different models, the number of predictive biomarkers and specific prognostic-predictive molecules were selected.

Main results and the role of chance

The main results of the study specifically identify ncRNA molecules that prognostically and predictively select a high-quality embryo suitable for IVF transmission from a low-quality embryo with 95% sensitivity and 80% specificity with an average accuracy of 85% in 4 different models. We also determined the minimum of 14 miRNA as prediction biomarkers. The developed model can predict embryo quality from the culture medium based on ncRNA results from sequence data and set the cut-off value for the expression and significance of individual miRNA molecules with respect to embryo quality. Furthermore, positive and negative correlations of miRNA molecules with different distributions in a high-quality embryo compared to a low-quality embryo were determined. The molecules identified in the embryo culture medium were organized according to their importance, resp. significance based on their significance coefficient. So far, there is no evidence of pending patents regarding the distribution of specific canonical miRNAs and iso-miRNA molecules analysed by massively parallel sequencing in terms of biological competence and embryo quality determination with multifactorial consideration of its variation. This is the first study focused on the success of the IVF process based on embryo quality prediction.

Limitations, reasons for caution

Exploratory data need to be validated in a larger scale study.

Wider implications of the findings: The given miRNA molecules and the software model can be used as a safe,non-invasive diagnostic test for the selection of a highly competent embryo. Canonical and iso-miRNA molecules from the study can be used in other forms of diagnostic assays, such as specific embryo selection probes and, plate hybridization assay.

Trial registration number

non clinical trials

OCaMIR-A Noninvasive, Diagnostic Signature for Early-Stage Ovarian Cancer: A Multi-cohort Retrospective and Prospective Study

PURPOSE

Due to the lack of effective screening approaches and early detection biomarkers, ovarian cancer has the highest mortality rates among gynecologic cancers. Herein, we undertook a systematic biomarker discovery and validation approach to identify microRNA (miRNA) biomarkers for the early detection of ovarian cancer.

EXPERIMENTAL DESIGN

During the discovery phase, we performed small RNA sequencing in stage I high-grade serous ovarian cancer (n = 31), which was subsequently validated in multiple, independent data sets (TCGA, n = 543; GSE65819, n = 87). Subsequently, we performed multivariate logistic regression-based training in a serum data set (GSE106817, n = 640), followed by its independent validation in three retrospective data sets (GSE31568, n = 85; GSE113486, n = 140; Czech Republic cohort, n = 192) and one prospective serum cohort (n = 95). In addition, we evaluated the specificity of OCaMIR, by comparing its performance in several other cancers (GSE31568 cohort, n = 369).

RESULTS

The OCaMIR demonstrated a robust diagnostic accuracy in the stage I high-grade serous ovarian cancer patients in the discovery cohort (AUC = 0.99), which was consistently reproducible in both stage I (AUC = 0.96) and all stage patients (AUC = 0.89) in the TCGA cohort. Logistic regression-based training and validation of OCaMIR achieved AUC values of 0.89 (GSE106817), 0.85 (GSE31568), 0.86 (GSE113486), and 0.82 (Czech Republic cohort) in the retrospective serum validation cohorts, as well as prospective validation cohort (AUC = 0.92). More importantly, OCaMIR demonstrated a significantly superior diagnostic performance compared with CA125 levels, even in stage I patients, and was more cost-effective, highlighting its potential role for screening and early detection of ovarian cancer.

CONCLUSIONS

Small RNA sequencing identified a robust noninvasive miRNA signature for early-stage serous ovarian cancer detection.

Novel mutations in TRPM6 gene associated with primary hypomagnesemia with secondary hypocalcemia. Case report

BACKGROUND

Primary hypomagnesemia with secondary hypocalcemia (HSH) is a rare genetic disorder. Dysfunctional transient receptor potential melastatin 6 causes impaired intestinal absorption of magnesium, leading to low serum levels accompanied by hypocalcemia. Typical signs at initial manifestation are generalized seizures, tetany, and/or muscle spasms.

CASE REPORT

We present a 5 w/o female manifesting tonic-clonic seizures. Laboratory tests detected severe hypomagnesemia and hypocalcemia. The molecular genetic analysis revealed two novel mutations within the TRPM6 gene c.3308dupC (p.Pro1104Thrfs*28) (p.P1104Tfs*28) and c.3958C>T (p.Gln1302*) (p.Q1302*) and the patient was successfully treated with Mg supplementation.

CONCLUSION

Ion disbalance should be taken into account in the differential diagnosis of infantile seizures. Accurate diagnosis of HSH together with appropriate treatment are crucial to prevent irreversible neurological outcomes.

Barriers in systemic delivery and preclinical testing of synthetic microRNAs in animal models: an experimental study on miR-215-5p mimic

Mus musculus is the most commonly used animal model in microRNA research; however, little is known about the endogenous miRNome of the animals used in the miRNA-targeting preclinical studies with the human xenografts. In the presented study, we evaluated the NOD/SCID gamma mouse model for the preclinical study of systemic miR-215-5p substitution with a semitelechelic poly[N-(2-hydroxypropyl)-methacrylamide]-based carrier conjugated with miR-215-5p-mimic via a reductively degradable disulfide bond. Murine mmu-miR-215-5p and human hsa-miR-215-5p have a high homology of mature sequences with only one nucleotide substitution. Due to the high homology of hsa-miR-215-5p and mmu-hsa-miR-215-5p, a similar expression in human and NOD/SCID gamma mice was expected. Expression of mmu-miR-215 in murine organs did not indicate tissue-specific expression and was highly expressed in all examined tissues. All animals included in the study showed a significantly higher concentration of miR-215-5p in the blood plasma compared to human blood plasma, where miR-215-5p is on the verge of a reliable detection limit. However, circulating mmu-miR-215-5p did not enter the human xenograft tumors generated with colorectal cancer cell lines since the levels of miR-215-5p in control tumors remained notably lower compared to those originally transfected with miR-215-5p. Finally, the systemic administration of polymer-miR-215-5p-mimic conjugate to the tail vein did not increase miR-215-5p in NOD/SCID gamma mouse blood plasma, organs, and subcutaneous tumors. It was impossible to distinguish hsa-miR-215-5p and mmu-miR-215-5p in the murine blood and organs due to the high expression of endogenous mmu-miR-215-5p. In conclusion, the examination of endogenous tissue and circulating miRNome of an experimental animal model of choice might be necessary for future miRNA studies focused on the systemic delivery of miRNA-based drugs conducted in the animal models.