An Interaction Network of the Human SEPT9 Established by Quantitative Mass Spectrometry

Septins regulate the organization of the actin cytoskeleton, vesicle transport and fusion, chromosome alignment and segregation, and cytokinesis in mammalian cells. SEPT9 is part of the core septin hetero-octamer in human cells which is composed of SEPT2, SEPT6, SEPT7, and SEPT9. SEPT9 has been linked to a variety of intracellular functions as well as to diseases and diverse types of cancer. A targeted high-throughput approach to systematically identify the interaction partners of SEPT9 has not yet been performed. We applied a quantitative proteomics approach to establish an interactome of SEPT9 in human fibroblast cells. Among the newly identified interaction partners were members of the myosin family and LIM domain containing proteins. Fluorescence microscopy of SEPT9 and its interaction partners provides additional evidence that SEPT9 might participate in vesicle transport from and to the plasma membrane as well as in the attachment of actin stress fibers to cellular adhesions

Pancreatic cancer-derived organoids – a disease modeling tool to predict drug response

[Background]: Organotypic cultures derived from pancreatic ductal adenocarcinoma (PDAC) termed pancreatic ductal cancer organoids (PDOs) recapitulate the primary cancer and can be derived from primary or metastatic biopsies. Although isolation and culture of patient-derived pancreatic organoids were established several years ago, pros and cons for individualized medicine have not been comprehensively investigated to date.[Methods]: We conducted a feasibility study, systematically comparing head-to-head patient-derived xenograft tumor (PDX) and PDX-derived organoids by rigorous immunohistochemical and molecular characterization. Subsequently, a drug testing platform was set up and validated in vivo. Patient-derived organoids were investigated as well.[Results]: First, PDOs faithfully recapitulated the morphology and marker protein expression patterns of the PDXs. Second, quantitative proteomes from the PDX as well as from corresponding organoid cultures showed high concordance. Third, genomic alterations, as assessed by array-based comparative genomic hybridization, revealed similar results in both groups. Fourth, we established a small-scale pharmacotyping platform adjusted to operate in parallel considering potential obstacles such as culture conditions, timing, drug dosing, and interpretation of the results. In vitro predictions were successfully validated in an in vivo xenograft trial. Translational proof-of-concept is exemplified in a patient with PDAC receiving palliative chemotherapy.[Conclusion]: Small-scale drug screening in organoids appears to be a feasible, robust and easy-to-handle disease modeling method to allow response predictions in parallel to daily clinical routine. Therefore, our fast and cost-efficient assay is a reasonable approach in a predictive clinical setting.The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Main funding is provided by the German Cancer Aid grant to A. Kleger (111879). Additional funding came from the Deutsche Forschungsgemeinschaft (DFG, K.L. 2544/1-1, and 1-2; GRK 2254/1 to T. Seufferlein), the BIU fund (Böhringer Ingelheim), the NDIMED-Verbund PancChip, and the Else-Kröner-Fresenius Memorial funding to A. Kleger. AK receives also funding from the DFG within the Heisenberg program and from the Baden-Württemberg Foundation via ExPo Chip. This project was also funded by ANR-DFG collaborative research project (ANR-18-CE92-0031, DFG KL 2544/5-1) to CJ and AK and via additional DFG funding KL 2544/6-1, KL 2544/7-1, KL 2544/1-1, and KL 2544/1-2 to AK. L. Perkhofer is funded by Bausteinprogramm of the Ulm University hospital. This work was supported by a project grant for André Lechel (Deutsche Krebshilfe/111264), for Patrick C. Hermann (Max Eder Fellowship 111746, Projektnummer 316249678 – SFB 1279, and Hector Foundation Cancer Research grant M65.1). Reinhild Rösler and parts of proteomics method development were funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – SFB 1074. Bruno Sainz Jr was funded by a Ramón y Cajal Merit Award from the Ministerio de Economía y Competitividad, Spain and a coordinated grant from the Fundación Asociación Española Contra el Cáncer (AECC).Peer reviewe