Rationale: Grb2-associated binder (Gab) docking proteins, consisting of Gab1, Gab2, and Gab3, have crucial roles in growth factor-dependent signaling. Various proangiogenic growth factors regulate angiogenesis and endothelial function. However, the roles of Gab proteins in angiogenesis remain elusive.Objective: To elucidate the role of Gab proteins in postnatal angiogenesis. Methods and Results: Endothelium-specific Gab1 knockout (Gab1ECKO) mice were viable and showed no obvious defects in vascular development. Therefore, we analyzed a hindlimb ischemia (HLI) model of control, Gab1ECKO, or conventional Gab2 knockout (Gab2KO) mice. Intriguingly, impaired blood flow recovery and necrosis in the operated limb was observed in all of Gab1ECKO, but not in control or Gab2KO mice. Among several proangiogenic growth factors, hepatocyte growth factor (HGF) induced the most prominent tyrosine phosphorylation of Gab1 and subsequent complex formation of Gab1 with SHP2 (Src homology-2-containing protein tyrosine phosphatase 2) and phosphatidylinositol 3-kinase subunit p85 in human endothelial cells (ECs). Gab1-SHP2 complex was required for HGF-induced migration and proliferation of ECs via extracellular

Angiogenesis inhibitors, such as sorafenib and axitinib, which target vascular endothelial growth factor (VEGF) signaling, are widely used for renal cell carcinoma, including metastasis. In this study, we report a case of cardiovascular adverse events of aortic dissection and cardiac dysfunction during treatment with sorafenib and axitinib for metastatic renal cell carcinoma. A 66-year-old man had been administered sorafenib for 2 years after nephrectomy due to renal cell carcinoma. To control the progression of metastatic lung tumor, axitinib was started after sorafenib for four years. During the treatment, angiotensin II type 1 receptor blockers and Ca antagonists were used to strictly control the axitinib-induced hypertension and proteinuria. Aortic dissection and cardiac dysfunction occurred coincidentally. Considering the critical role of VEGF signaling in the homeostasis of the cardiovascular system, we speculated that the long-term use of axitinib and sorafenib directly influenced the initiation of aortic dissection and cardiac dysfunction. Although the precise mechanisms underlying the aortic dissection and cardiac dysfunction induced by angiogenesis inhibition are still elusive, onco-cardiologists and oncologists should pay careful attention to cardiovascular toxicity and complications in patients with cancer, particularly patients undergoing long-term cancer treatment.

Objective Oral anticoagulants (OACs), which include direct oral anticoagulants (DOACs) and warfarin, are widely used for the prevention of thromboembolic events in patients with atrial fibrillation (AF). Cancer is associated with a prothrombotic state as well as an increased bleeding risk. Few data are available on the efficacy and safety of OACs in Japanese cancer patients with AF. We sought to investigate the efficacy and safety of OACs in this population. Methods This retrospective cohort study included active cancer patients in whom AF was recorded by electrocardiography in our hospital from January 2014 to December 2016 and who were treated with DOACs or warfarin. Patients were followed for 1 year. The study outcomes were stroke or systemic embolism and major bleeding. Result A total of 224 patients with AF and active cancer were treated with OACs (DOACs, n=127; warfarin, n=97). Overall, stroke or systemic embolism and major bleeding occurred in seven (3.8%/year) and eight (4.9%/year) patients, respectively. Stroke or systemic embolism occurred in three patients in the DOAC group (2.8%/year) and four patients in the warfarin group (5.4%/year). Major bleeding occurred in four patients in the DOAC group (4.0%/year) and four patients in the warfarin group (6.5%/year). Conclusion The rates of stroke or systemic embolism and major bleeding events were not negligible among Japanese cancer patients with AF receiving OACs. Further investigations on the optimal management of Japanese patients with AF and cancer are needed.

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