Myeloproliferative neoplasms (MPNs), a group of malignant hematological disorders, occur as a consequence of somatic mutations in the hematopoietic stem cell compartment and show excessive accumulation of mature myeloid cells in the blood. A major cause of morbidity and mortality in these patients is the marked prothrombotic state leading to venous and arterial thrombosis, including myocardial infarction (MI), deep vein thrombosis (DVT), and strokes. Additionally, many MPN patients suffer from inflammation-mediated constitutional symptoms, such as fever, night sweats, fatigue, and cachexia. The chronic inflammatory syndrome in MPNs is associated with the up-regulation of various inflammatory cytokines in patients and is involved in the formation of the so-called MPN thromboinflammation. JAK2-V617F, the most prevalent mutation in MPNs, has been shown to activate a number of integrins on mature myeloid cells, including granulocytes and erythrocytes, which increase adhesion and drive venous thrombosis in murine knock-in/out models. This review aims to shed light on the current understanding of thromboinflammation, involvement of neutrophils in the prothrombotic state, plausible molecular mechanisms triggering the process of thrombosis, and potential novel therapeutic targets for developing effective strategies to reduce the MPN disease burden.

Background: Hepatocellular carcinoma (HCC) represents a major health burden with limited curative treatment options. There is a substantial unmet need to develop innovative approaches to impact the progression of advanced HCC. Haprolid is a novel natural component isolated from myxobacteria. Haprolid has been reported as a potent selective cytotoxin against a panel of tumor cells in recent studies including HCC cells. The aims of this study are to evaluate the antitumor effect of haprolid in HCC and to understand its underlying molecular mechanisms. Methods: The efficacy of haprolid was evaluated in human HCC cell lines (Huh-7, Hep3B and HepG2) and xenograft tumors (NMRI-Foxn1^nu mice with injection of Hep3B cells). Cytotoxic activity of haprolid was determined by the WST-1 and crystal violet assay. Wound healing, transwell and tumorsphere assays were performed to investigate migration and invasion of HCC cells. Apoptosis and cell-cycle distribution were measured by flow cytometry. The effects of haprolid on the Rb/E2F and Akt/mTOR pathway were examined by immunoblotting and immunohistochemistry. Results: haprolid treatment significantly inhibited cell proliferation, migration and invasion in vitro. The epithelial–mesenchymal transition (EMT) was impaired by haprolid treatment and the expression level of N-cadherin, vimentin and Snail was downregulated. Moreover, growth of HCC cells in vitro was suppressed by inhibition of G1/S transition, and partially by induction of apoptosis. The drug induced downregulation of cell cycle regulatory proteins cyclin A, cyclin B and CDK2 and induced upregulation of p21 and p27. Further evidence showed that these effects of haprolid were associated with Rb/E2F downregulation and Akt/mTOR inhibition. Finally, in vivo nude mice experiments demonstrated significant inhibition of tumor growth upon haprolid treatment. Conclusion: Our results show that haprolid inhibits the growth of HCC through dual inhibition of Rb/E2F and Akt/mTOR pathways. Therefore, haprolid might be considered as a new and promising candidate for the palliative therapy of HCC.

323 Background: Adiponectin is the key adipokine, which plays an important role in health and disease such as obesity, diabetes, and cancer. Adiponectin is reduced in different tumor types, especially in obesity-related cancer, and recent studies showed that Adiponectin had a potential anti-cancer effect. Obesity is a risk factor for various tumor diseases including cholangiocarcinoma (CC), the second most common primary hepatic cancer. The aim of this study is to investigate for the first time the anti-cancer effect of AdipoR agonist in CC cell lines and a CC engineered mouse model. Methods: Human CC cell lines (TFK-1 and SZ-1) and CC engineered mice (Alb-Cre/KRAS^G12D/p53^L/L) were used to investigate the anti-cancer effects of an AdipoR agonist (2-(4-Benzoylphenoxy)-N-[1-(phenylmethyl)-4-piperidinyl]-acetamide). Cell proliferation, migration, invasion, colony formation, apoptosis assay were applied to evaluate the effect of AdipoR agonist in vitro. In addition, important cancer signalling pathways and targets were analysed by Western Blot. Mice (n = 12) were treated with AdipoR or verhicle and tumor burden and survival were monitored. Results: AdipoR agonist suppressed proliferation, migration, invasion, colony formation and apoptosis in CC cells. AdipoR agonist regulated the expression of different proteins such as EMT markers, pAMPK, pSTAT3, and PARP, which have pivotal functions in cholangiocarcinogenesis. AdipoR agonist also prolonged survival time in a CC engineered mouse model. Conclusions: Our data revealed that AdipoR agonist inhibited successfully cell proliferation, migration, invasion, colony formation and apoptosis in vitro, and prolonged mice survival in vivo through regulation of crucial signaling pathways in cholangiocarcinogenesis. These results suggested that AdipoR agonist might become a new potential candidate for CC treatment in the future.

The molecular mechanisms driving splenomegaly in myeloproliferative neoplasms (MPNs) remain poorly understood. Utilizing the Jak2-V617F knock-in mouse model, we investigated the role of β1- and β2-integrins in regulating spleen volume and spleen weight. The response to neutralizing antibodies against VLA-4 and the β2-integrin chain, as well as to isotype controls, was evaluated by serial intraindividual magnetic resonance imaging, by assessment of spleen weight and by analysis of the cellular composition of spleens. Short-term anti-VLA-4/β2-integrin treatment (applied on day 1 and evaluated at day 8) significantly reduced the spleen volume by 30% compared with the immunoglobulin G (IgG) control. At the cellular level, anti-integrin treatment led to a substantial 30% decrease in erythroblast counts and a 23% reduction in basophilic erythroblasts within the spleen, as compared with the isotype control. Furthermore, immunohistochemistry analysis of spleen sections revealed that CD71 (= Transferrin receptor protein 1) expression in spleen remained largely unchanged, whereas there was a clear reduction in Ter119 expression upon anti-integrin treatment. These data suggest that the substantial decrease in erythroblasts following anti-integrin treatment is a primary factor contributing to the overall reduction in spleen size. To study the spleen architecture, multiepitope ligand cartography (MELC) analysis of spleen sections was applied. This demonstrated that the spatial distribution of the marginal zone, red pulp, and white pulp remained unaltered upon anti-integrin treatment in JAK2-V617F knock-in mice. In summary, the present study identified a previously unrecognized role of the β1-integrin VLA-4 and of β2-integrin chains in extramedullary erythropoiesis of the spleen in JAK2-V617F-induced disease.