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Aim: Chemoresistance is a major cause of treatment failure in colorectal cancer (CRC) therapy. In this study, the impact of the IGF2BP family of RNA-binding proteins on CRC chemoresistance was investigated using in silico, in vitro, and in vivo approaches. Methods: Gene expression data from a well-characterized cohort and publicly available cross-linking immunoprecipitation sequencing (CLIP-Seq) data were collected. Resistance to chemotherapeutics was assessed in patient-derived xenografts (PDXs) and patient-derived organoids (PDOs). Functional studies were performed in 2D and 3D cell culture models, including proliferation, spheroid growth, and mitochondrial respiration analyses. Results: We identified IGF2BP2 as the most abundant IGF2BP in primary and metastastatic CRC, correlating with tumor stage in patient samples and tumor growth in PDXs. IGF2BP2 expression in primary tumor tissue was significantly associated with resistance to selumetinib, gefitinib, and regorafenib in PDOs and to 5-fluorouracil and oxaliplatin in PDX in vivo. IGF2BP2 knockout (KO) HCT116 cells were more susceptible to regorafenib in 2D and to oxaliplatin, selumitinib, and nintedanib in 3D cell culture. Further, a bioinformatic analysis using CLIP data suggested stabilization of target transcripts in primary and metastatic tumors. Measurement of oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) revealed a decreased basal OCR and an increase in glycolytic ATP production rate in IGF2BP2 KO. In addition, real-time reverse transcriptase polymerase chain reaction (qPCR) analysis confirmed decreased expression of genes of the respiratory chain complex I, complex IV, and the outer mitochondrial membrane in IGF2BP2 KO cells. Conclusions: IGF2BP2 correlates with CRC tumor growth in vivo and promotes chemoresistance by altering mitochondrial respiratory chain metabolism. As a druggable target, IGF2BP2 could be used in future CRC therapy to overcome CRC chemoresistance.

The persistence of SARS-CoV-2 after death of infected individuals is unclear. The aim of this study was to investigate the presence of SARS-CoV-2 RNA in different organs in correlation with tissue damage and post-mortem viral dynamics in COVID-19 deceased. Twenty-eight patients (17 males, 11 females; age 66–96 years; mean 82.9, median 82.5 years) diagnosed with COVID-19 were studied. Swabs were taken post-mortem during autopsy (N = 19) from the throat, both lungs, intestine, gallbladder, and brain or without autopsy (N = 9) only from the throat. Selective amplification of target nucleic acid from the samples was achieved by using primers for ORF1a/b non-structural region and the structural protein envelope E-gene of the virus. The results of 125 post-mortem and 47 ante-mortem swabs were presented as cycle threshold (Ct) values and categorized as strong, moderate, and weak. Viral RNA was detected more frequently in the lungs and throat than in the intestine. Blood, bile, and the brain were negative. Consecutive throat swabs were positive up to 128 h after death without significant increase of Ct values. All lungs showed diffuse alveolar damage, thrombosis, and infarction and less frequently bronchopneumonia irrespective of Ct values. In 30% the intestine revealed focal ischemic changes. Nucleocapsid protein of SARS-CoV-2 was detected by immunohistochemistry in bronchial and intestinal epithelium, bronchial glands, and pneumocytes. In conclusion, viral RNA is still present several days after death, most frequently in the respiratory tract and associated with severe and fatal organ damage. Potential infectivity cannot be ruled out post-mortem. Version of record

COVID-19 wird als systemische Erkrankung eingestuft. Ein schwerer Verlauf mit tödlichem Ausgang ist möglich und unvorhersehbar. Fragestellung Welche Organsysteme sind primär betroffen? Welche Organveränderungen prädisponieren für einen ungünstigen Verlauf? Welche Organschädigungen finden sich bei letalem Ausgang? Material und Methode Daten aus publizierten Obduktionsstudien (davon 28 eigene publizierte Fälle) in Hinblick auf Organschädigung und mögliche Todesursachen. Ergebnisse Die schwersten Veränderungen finden sich in den Lungen in Form eines diffusen Alveolarschadens als akutes Atemnotsyndrom des Erwachsenen (ARDS), zum Teil bereits mit Fibrose. Thrombosen in kleinen bis mittelgroßen Pulmonalarterien sind mit Lungeninfarkten vergesellschaftet. Häufige Komplikationen sind bakterielle Bronchopneumonien, seltener Pilzpneumonien. Pulmonale Thromboembolien finden sich in 2030 % der tödlichen Verläufe, auch bei Fehlen einer tiefen Beinvenenthrombose. Eine intestinale Beteiligung von COVID-19 kann mit ischämischer Schädigung des Darmes einhergehen, in erster Linie bedingt durch Schock oder lokale Thrombose. Die Nieren zeigen eine akute Tubulusschädigung als Ausdruck eines akuten Nierenversagens, Lymphknoten und Milz einen Schwund der Lymphozyten, die Nebennierenrinde eine Hyperplasie. In der Leber finden sich häufig eine Steatose, Leberzellnekrosen, ein portales Entzündungsinfiltrat und eine Proliferation der Kupffer-Zellen. Häufige Grunderkrankungen sind in den Autopsiekollektiven arterieller Hypertonus mit hypertensiver und ischämischer Kardiomyopathie und Diabetes mellitus. In großen bevölkerungsbasierten Studien ergibt sich aber für Hypertoniker im Gegensatz zu Diabetikern kein erhöhtes Mortalitätsrisiko. Schlussfolgerungen Pulmonale Kreislaufstörungen mit arteriellen Thrombosen, Infarkten und Pneumonien sind wesentliche und oft letale Komplikationen des ARDS bei COVID-19. Die Erkenntnisse aus Obduktionsstudien haben Therapie und Prophylaxe beeinflusst. COVID-19 is considered a systemic disease. A severe course with fatal outcome is possible and unpredictable. Objectives Which organ systems are predominantly involved? Which diseases are predisposed for a fatal course? Which organ changes are found with lethal outcome? Materials and methods Data from published autopsy studies (28 cases by our group) with respect to organ changes and possible cause of death. Results The most severe alterations are found in the lungs by diffuse alveolar damage as a symptom of an acute respiratory distress syndrome (ARDS), in part with fibrosis. Thrombosis of small- to mid-sized pulmonary arteries is associated with hemorrhagic lung infarction. Frequent complications are bacterial pneumonias and less frequently fungal pneumonias by aspergillus. Pulmonary thromboembolism is found in 2030% of lethal courses, also in the absence of deep venous thrombosis. Intestinal involvement of COVID-19 can be associated with intestinal ischemia, caused by shock or local thrombosis. In most cases, the kidneys display acute tubular injury reflecting acute renal failure, depletion of lymphocytes in the lymph nodes and spleen, and hyperplastic adrenal glands. The liver frequently reveals steatosis, liver cell necrosis, portal inflammation, and proliferation of Kupffer cells. Important preexisting diseases in autopsy studies are arterial hypertension with hypertensive and ischemic cardiomyopathy and diabetes mellitus but large population-based studies reveal increased risk of mortality only for diabetes mellitus not for arterial hypertension. Conclusions Alterations of the pulmonary circulation with pulmonary arterial thrombosis, infarction, and bacterial pneumonia are important and often lethal complications of COVID-19-associated ARDS. Findings from autopsy studies have influenced therapy and prophylaxis. Version of record