The 1ALCTL and 1BLCTL isoforms of Arg/Abl2 induce fibroblast activation and extra cellular matrix remodelling differently

The Nanomechanical Properties of CLL Cells Are Linked to the Actin Cytoskeleton and Are a Potential Target of BTK Inhibitors

Chronic lymphocytic leukemia (CLL) is an incurable disease characterized by an intense trafficking of the leukemic cells between the peripheral blood and lymphoid tissues. It is known that the ability of lymphocytes to recirculate strongly depends on their capability to rapidly rearrange their cytoskeleton and adapt to external cues; however, little is known about the differences occurring between CLL and healthy B cells during these processes. To investigate this point, we applied a single-cell optical (super resolution microscopy) and nanomechanical approaches (atomic force microscopy, real-time deformability cytometry) to both CLL and healthy B lymphocytes and compared their behavior. We demonstrated that CLL cells have a specific actomyosin complex organization and altered mechanical properties in comparison to their healthy counterpart. To evaluate the clinical relevance of our findings, we treated the cells in vitro with the Bruton's tyrosine kinase inhibitors and we found for the first time that the drug restores the CLL cells mechanical properties to a healthy phenotype and activates the actomyosin complex. We further validated these results in vivo on CLL cells isolated from patients undergoing ibrutinib treatment. Our results suggest that CLL cells' mechanical properties are linked to their actin cytoskeleton organization and might be involved in novel mechanisms of drug resistance, thus becoming a new potential therapeutic target aiming at the normalization of the mechanical fingerprints of the leukemic cells.

High glucose induces an activated state of partial epithelial-mesenchymal transition in human primary tubular cell cultures

Tubulointerstitial fibrosis is observed in diabetic nephropathy. It is still debated whether tubular cells, undergoing epithelial-mesenchymal transition (EMT) in high glucose (HG) conditions, may contribute to interstitial fibrosis development. In this study, we investigated the phenotypic and molecular EMT-like changes and the alteration of inflammatory and fibrogenic secretome induced by HG in human primary tubular cell cultures. Taking advantage of this in vitro cell model composed of proximal and distal tubular cells, we showed that HG-treated tubular cells acquired a fibroblast-like morphology with increased cytoplasmic stress fibers, maintaining the expression of the epithelial markers specific of proximal and distal tubular cells. HG increased Snail1, miRNA210 and Vimentin mesenchymal markers, decreased N-cadherin expression and migration ability of primary tubular cells, while E-cadherin expression and focal adhesion distribution were not affected. Furthermore, HG treatment of tubular cells altered the inflammatory cytokine secretion creating a secretome able to enhance the proliferation and migration of fibroblasts. Our findings show that HG promotes an activated state of partial EMT in human tubular primary cells and induces a pro-inflammatory and pro-fibrogenic microenvironment, supporting the active role of tubular cells in diabetic nephropathy onset.

The NSs Protein Encoded by the Virulent Strain of Rift Valley Fever Virus Targets the Expression of Abl2 and the Actin Cytoskeleton of the Host, Affecting Cell Mobility, Cell Shape, and Cell-Cell Adhesion

Rift Valley fever virus (RVFV) is a highly pathogenic zoonotic arbovirus endemic in many African countries and the Arabian Peninsula. Animal infections cause high rates of mortality and abortion among sheep, goats, and cattle. In humans, an estimated 1 to 2% of RVFV infections result in severe disease (encephalitis, hepatitis, or retinitis) with a high rate of lethality when associated with hemorrhagic fever. The RVFV NSs protein, which is the main virulence factor, counteracts the host innate antiviral response to favor viral replication and spread. However, the mechanisms underlying RVFV-induced cytopathic effects and the role of NSs in these alterations remain for the most part unknown. In this work, we have analyzed the effects of NSs expression on the actin cytoskeleton while conducting infections with the NSs-expressing virulent (ZH548) and attenuated (MP12) strains of RVFV and the non-NSs-expressing avirulent (ZH548ΔNSs) strain, as well as after the ectopic expression of NSs. In macrophages, fibroblasts, and hepatocytes, NSs expression prevented the upregulation of Abl2 (a major regulator of the actin cytoskeleton) expression otherwise induced by avirulent infections and identified here as part of the antiviral response. The presence of NSs was also linked to an increased mobility of ZH548-infected cells compared to ZH548ΔNSs-infected fibroblasts and to strong changes in cell morphology in nonmigrating hepatocytes, with reduction of lamellipodia, cell spreading, and dissolution of adherens junctions reminiscent of the ZH548-induced cytopathic effects observed in vivo Finally, we show evidence of the presence of NSs within long actin-rich structures associated with NSs dissemination from NSs-expressing toward non-NSs-expressing cells.IMPORTANCE Rift Valley fever virus (RVFV) is a dangerous human and animal pathogen that was ranked by the World Health Organization in 2018 as among the eight pathogens of most concern for being likely to cause wide epidemics in the near future and for which there are no, or insufficient, countermeasures. The focus of this work is to address the question of the mechanisms underlying RVFV-induced cytopathic effects that participate in RVFV pathogenicity. We demonstrate here that RVFV targets cell adhesion and the actin cytoskeleton at the transcriptional and cellular level, affecting cell mobility and inducing cell shape collapse, along with distortion of cell-cell adhesion. All these effects may participate in RVFV-induced pathogenicity, facilitate virulent RVFV dissemination, and thus constitute interesting potential targets for future development of antiviral therapeutic strategies that, in the case of RVFV, as with several other emerging arboviruses, are presently lacking.

Emerging Kinase Therapeutic Targets in Pancreatic Ductal Adenocarcinoma and Pancreatic Cancer Desmoplasia

Kinase drug discovery represents an active area of therapeutic research, with previous pharmaceutical success improving patient outcomes across a wide variety of human diseases. In pancreatic ductal adenocarcinoma (PDAC), innovative pharmaceutical strategies such as kinase targeting have been unable to appreciably increase patient survival. This may be due, in part, to unchecked desmoplastic reactions to pancreatic tumors. Desmoplastic stroma enhances tumor development and progression while simultaneously restricting drug delivery to the tumor cells it protects. Emerging evidence indicates that many of the pathologic fibrotic processes directly or indirectly supporting desmoplasia may be driven by targetable protein tyrosine kinases such as Fyn-related kinase (FRK); B lymphoid kinase (BLK); hemopoietic cell kinase (HCK); ABL proto-oncogene 2 kinase (ABL2); discoidin domain receptor 1 kinase (DDR1); Lck/Yes-related novel kinase (LYN); ephrin receptor A8 kinase (EPHA8); FYN proto-oncogene kinase (FYN); lymphocyte cell-specific kinase (LCK); tec protein kinase (TEC). Herein, we review literature related to these kinases and posit signaling networks, mechanisms, and biochemical relationships by which this group may contribute to PDAC tumor growth and desmoplasia.

Kinome Array Profiling of Patient-Derived Pancreatic Ductal Adenocarcinoma Identifies Differentially Active Protein Tyrosine Kinases

Pancreatic cancer remains one of the most difficult malignancies to treat. Minimal improvements in patient outcomes and persistently abysmal patient survival rates underscore the great need for new treatment strategies. Currently, there is intense interest in therapeutic strategies that target tyrosine protein kinases. Here, we employed kinome arrays and bioinformatic pipelines capable of identifying differentially active protein tyrosine kinases in different patient-derived pancreatic ductal adenocarcinoma (PDAC) cell lines and wild-type pancreatic tissue to investigate the unique kinomic networks of PDAC samples and posit novel target kinases for pancreatic cancer therapy. Consistent with previously described reports, the resultant peptide-based kinome array profiles identified increased protein tyrosine kinase activity in pancreatic cancer for the following kinases: epidermal growth factor receptor (EGFR), fms related receptor tyrosine kinase 4/vascular endothelial growth factor receptor 3 (FLT4/VEGFR-3), insulin receptor (INSR), ephrin receptor A2 (EPHA2), platelet derived growth factor receptor alpha (PDGFRA), SRC proto-oncogene kinase (SRC), and tyrosine kinase non receptor 2 (TNK2). Furthermore, this study identified increased activity for protein tyrosine kinases with limited prior evidence of differential activity in pancreatic cancer. These protein tyrosine kinases include B lymphoid kinase (BLK), Fyn-related kinase (FRK), Lck/Yes-related novel kinase (LYN), FYN proto-oncogene kinase (FYN), lymphocyte cell-specific kinase (LCK), tec protein kinase (TEC), hemopoietic cell kinase (HCK), ABL proto-oncogene 2 kinase (ABL2), discoidin domain receptor 1 kinase (DDR1), and ephrin receptor A8 kinase (EPHA8). Together, these results support the utility of peptide array kinomic analyses in the generation of potential candidate kinases for future pancreatic cancer therapeutic development.

First person – Barbara Torsello

First Person is a series of interviews with the first authors of a selection of papers published in Biology Open, helping early-career researchers promote themselves alongside their papers. Barbara Torsello is first author on ‘ The 1ALCTL and 1BLCTL isoforms of Arg/Abl2 induce fibroblast activation and extra cellular matrix remodelling differently’, published in BiO. Barbara is a Research Assistant in the lab of Roberto Perego at School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy, investigating the role of Abl2 isoforms in fibroblast activation.