Anti-RASA1 monoclonal antibody, clone 2I3

Background & Aims: Aberrant activation of the RAS pathway is ubiquitous in human hepatocarcinogenesis, but the molecular mechanisms leading to RAS induction in the absence of RAS mutations remain under-investigated. We defined the role of Ras GTPase activating proteins (GAPs) in the constitutive activity of Ras signaling during human hepatocarcinogenesis. Methods: The mutation status of RAS genes and RAS effectors was assessed in a collection of human hepatocellular carcinomas (HCC). Levels of RAS GAPs (RASA1-4, RASAL1, nGAP, SYNGAP1, DAB2IP, and NF1) and the RASAL1 upstream inducer PITX1 were determined by real-time RT-PCR and immunoblotting. The promoter and genomic status of RASAL1, DAB2IP, NF1, and PITX1 were assessed by methylation assays and microsatellite analysis. Effects of RASAL1. DAB2IP, and PITX1 on HCC growth were evaluated by transfection and siRNA analyses of HCC cell lines. Results: In the absence of Ras mutations, downregulation of at least one RAS GAP (RASAL1, DAB2IP, or NF1) was found in all HCC samples. Low levels of DAB2IP and PITX1 were detected mostly in a HCC subclass from patients with poor survival, indicating that these proteins control tumor aggressiveness. In HCC cells, reactivation of RASAL1, DAB2IP, and PITX1 inhibited proliferation and induced apoptosis, whereas their silencing increased proliferation and resistance to apoptosis. Conclusions: Selective suppression of RASAL1, DAB2IP, or NF1 RAS GAPs results in unrestrained activation of Ras signaling in the presence of wild-type RAS in HCC. Published by Elsevier B.V. on behalf of the European Association for the Study of the Liver.

Objectives Parkes Weber syndrome is a congenital vascular malformation which consists of capillary malformation, venous malformation, lymphatic malformation, and arteriovenous malformation. Although Parkes Weber syndrome is a clinically distinctive entity with serious complications, it is still frequently misdiagnosed as Klippel-Trenaunay syndrome that consists of the triad capillary malformation, venous malformation, and lymphatic malformation. Methods We performed a systematic review investigating clinical, diagnostic, and treatment modalities of Parkes Weber syndrome (PubMed/MEDLINE, Embase, and Cochrane databases). Thirty-six publications (48 patients) fulfilled the eligibility criteria. Results The median age of patients was 23 years (IQR, 8-32), and 24 (50.0%) were males. Lower extremity was affected in 42 (87.5%) and upper extremity in 6 (12.5%) patients; 15 (31.3%) patients developed high-output heart failure; 12 (25.0%) patients had chronic venous ulcerations, whereas 4 (8.3%) manifested distal arterial ischemia. The spinal arteriovenous malformations were reported in six (12.5%) patients and coexistence of aneurysmatic disease in five (10.4%) patients. The most frequently utilized invasive treatments were embotherapy followed by amputation and surgical arteriovenous malformation resection, and occasionally stent-graft implantation. All modalities showed clinical improvement. However, long follow-up and outcome remained unclear. Conclusion A diagnosis of Parkes Weber syndrome should be made on the presence of capillary malformation, venous malformation, lymphatic malformation, and arteriovenous malformation (as main defect) in overgrowth extremity. Arteriovenous malformation presents the criterion for distinguishing Parkes Weber syndrome from Klippel-Trenaunay syndrome, which is substantial for treatment strategy. The primary management goal should be patient's quality of life improvement and complication reduction. Embolization alone/combined with surgical resection targeting occlusion or removal of arteriovenous malformation nidus reliably leads to clinical improvement.