The non-receptor protein tyrosine phosphatase SHP2, encoded by PTPN11, has an important role in signal transduction downstream of growth factor receptor signalling and was the first reported ...oncogenic tyrosine phosphatase. Activating mutations of SHP2 have been associated with developmental pathologies such as Noonan syndrome and are found in multiple cancer types, including leukaemia, lung and breast cancer and neuroblastoma. SHP2 is ubiquitously expressed and regulates cell survival and proliferation primarily through activation of the RAS–ERK signalling pathway. It is also a key mediator of the programmed cell death 1 (PD-1) and B- and T-lymphocyte attenuator (BTLA) immune checkpoint pathways. Reduction of SHP2 activity suppresses tumour cell growth and is a potential target of cancer therapy. Here we report the discovery of a highly potent (IC50 = 0.071 μM), selective and orally bioavailable small-molecule SHP2 inhibitor, SHP099, that stabilizes SHP2 in an auto-inhibited conformation. SHP099 concurrently binds to the interface of the N-terminal SH2, C-terminal SH2, and protein tyrosine phosphatase domains, thus inhibiting SHP2 activity through an allosteric mechanism. SHP099 suppresses RAS–ERK signalling to inhibit the proliferation of receptor-tyrosine-kinase-driven human cancer cells in vitro and is efficacious in mouse tumour xenograft models. Together, these data demonstrate that pharmacological inhibition of SHP2 is a valid therapeutic approach for the treatment of cancers.
Sperm are haploid but must be functionally equivalent to distribute alleles equally among progeny. Accordingly, gene products are shared through spermatid cytoplasmic bridges that erase phenotypic ...differences between individual haploid sperm. Here, we show that a large class of mammalian genes are not completely shared across these bridges. We call these genes "genoinformative markers" (GIMs) and show that a subset can act as selfish genetic elements that spread alleles unevenly through murine, bovine, and human populations. We identify evolutionary pressure to avoid conflict between sperm and somatic function as GIMs are enriched for testis-specific gene expression, paralogs, and isoforms. Therefore, GIMs and sperm-level natural selection may help to explain why testis gene expression patterns are an outlier relative to all other tissues.
The inhibitor of apoptosis proteins (IAPs) have recently been shown to modulate nuclear factor κB (NF-κB) signaling downstream of tumor necrosis factor (TNF) family receptors, positioning them as ...essential survival factors in several cancer cell lines, as indicated by the cytotoxic activity of several novel small molecule IAP antagonists. In addition to roles in cancer, increasing evidence suggests that IAPs have an important function in immunity; however, the impact of IAP antagonists on antitumor immune responses is unknown. In this study, we examine the consequences of IAP antagonism on T cell function in vitro and in the context of a tumor vaccine in vivo. We find that IAP antagonists can augment human and mouse T cell responses to physiologically relevant stimuli. The activity of IAP antagonists depends on the activation of NF-κB2 signaling, a mechanism paralleling that responsible for the cytotoxic activity in cancer cells. We further show that IAP antagonists can augment both prophylactic and therapeutic antitumor vaccines in vivo. These findings indicate an important role for the IAPs in regulating T cell-dependent responses and suggest that targeting IAPs using small molecule antagonists may be a strategy for developing novel immunomodulating therapies against cancer.
SHP2 is a nonreceptor protein tyrosine phosphatase encoded by the PTPN11 gene and is involved in cell growth and differentiation via the MAPK signaling pathway. SHP2 also plays an important role in ...the programed cell death pathway (PD-1/PD-L1). As an oncoprotein as well as a potential immunomodulator, controlling SHP2 activity is of high therapeutic interest. As part of our comprehensive program targeting SHP2, we identified multiple allosteric binding modes of inhibition and optimized numerous chemical scaffolds in parallel. In this drug annotation report, we detail the identification and optimization of the pyrazine class of allosteric SHP2 inhibitors. Structure and property based drug design enabled the identification of protein–ligand interactions, potent cellular inhibition, control of physicochemical, pharmaceutical and selectivity properties, and potent in vivo antitumor activity. These studies culminated in the discovery of TNO155, (3S,4S)-8-(6-amino-5-((2-amino-3-chloropyridin-4-yl)thio)pyrazin-2-yl)-3-methyl-2-oxa-8-azaspiro4.5decan-4-amine (1), a highly potent, selective, orally efficacious, and first-in-class SHP2 inhibitor currently in clinical trials for cancer.
Smac mimetic compounds targeting the inhibitor of apoptosis proteins (IAP) baculoviral IAP repeat-3 domain are presumed to reduce the threshold for apoptotic cell death by alleviating caspase-9 ...repression. We explored this tenet in an unbiased manner by searching for small interfering RNAs that are able to confer resistance to the Smac mimetic compound LBW242. Among the screening hits were multiple components of the tumor necrosis factor alpha (TNFalpha) signaling pathway as well as X-linked inhibitor of apoptosis (XIAP) itself. Here, we show that in a subset of highly sensitive tumor cell lines, activity of LBW242 is dependent on TNFalpha signaling. Mechanistic studies indicate that in this context, XIAP is a positive modulator of TNFalpha induction whereas cellular inhibitor of apoptosis protein 1 negatively regulates TNFalpha-mediated apoptosis.
Objective: Cotransplantation of a donor kidney along with a heart allograft can induce tolerance to both organs and prevent cardiac allograft vasculopathy in miniature swine. To determine whether the ...tolerogenic effect of donor kidney cotransplantation was due to an effect specific to the kidney graft or to an increase in donor antigen load, we compared heart-kidney recipients with recipients receiving two class I disparate hearts or with recipients receiving donor peripheral mononuclear cells at the time of isolated heart transplantation.
Methods: Recipients of major histocompatibility complex class I disparate allografts received 12 days of cyclosporine (INN: ciclosporin; 10-13 mg/kg administered intravenously on days 0-11). Group 1 animals received a heart alone (n = 5). Group 2 animals received heart and kidney allografts (n = 4). Group 3 animals received two major histocompatibility complex–matched heart allografts (n = 4). Two double-heart recipients were thymectomized 21 days before transplantation. Group 4 animals received a heart allograft and an infusion of high-dose donor peripheral blood leukocytes (2.5 × 10
9 cells/kg, n = 2).
Results: Vasculopathy developed in group 1 recipients and the allografts were rejected within 55 days. Group 2 recipients accepted their heart and kidney allografts indefinitely without vasculopathy. Euthymic recipients from group 3 accepted their hearts long-term (>190 and >197 days), but vascular lesions developed. In thymectomized recipients from group 3, the hearts were rejected in 63 and 96 days with severe vasculopathy. Group 4 recipients demonstrated transient macrochimerism but their hearts were rejected within 47 and 63 days.
Conclusions: The beneficial effects of donor kidney cotransplantation on cardiac allograft survival and prevention of cardiac allograft vasculopathy are likely to involve both an increase in donor antigen load and an effect specific to the kidney allograft. (J Thorac Cardiovasc Surg 2000;119:709-19)
: Miniature swine are considered to be potential donors for clinical cardiac transplantation. However, it is unclear how an appropriately sized porcine donor will be selected for a particular human ...recipient. To address this issue, we performed a morphometric study of the swine heart using transthoracic echocardiography (n = 26) to determine the diameters of the aortic annulus and root, pulmonary artery annulus, and mitral valve annulus. We also obtained direct ex vivo measurements of swine heart weight and linear dimensions (n = 71). Relationships between a swine's height, weight, length, chest circumference and these internal and external cardiac dimensions are described. The strongest correlations were found between a pig's body length and its aortic annulus and root diameters (r‐values = 0.97). These relationships are accurately described by univariate linear regression models. By cross‐relating our morphometric measurements of aortic annulus diameter in the miniature swine with normative human data, we were able to develop a nomogram, relating swine length and human height, which predicts which miniature swine would donate the best size‐matched heart for a particular human recipient.
The mechanisms and treatment of cardiac allograft vasculopathy (CAV) remain elusive. We have used partially inbred miniature swine to determine the role of class I MHC antigens in the pathogenesis of ...CAV and to determine whether acquired tolerance to donor antigen can prevent the development of CAV in large animals.
Previous studies demonstrated that miniature swine treated with 12 days of cyclosporine (CsA) after the transplantation of MHC class I-disparate kidney allografts all became tolerant to the donor kidneys and survived indefinitely. In the present study, heart allografts were transplanted across the same MHC class I disparity in CsA-treated swine.
Unlike kidney allografts, heart allografts were rejected in 33-55 days. By postoperative day 28, all cardiac allografts had developed the intimal proliferation characteristic of CAV. When hearts and kidneys from the same donors were transplanted simultaneously into class I-disparate, CsA-treated recipients, the hosts became tolerant to their cardiac allografts and survived long-term. Furthermore, none of the hearts from the combined heart/kidney recipients developed evidence of CAV. Thus, this report demonstrates that: (1) MHC class I antigens play an important role in the pathogenesis of CAV, (2) the specific unresponsiveness to donor class I antigen induced by a class I-disparate kidney protects a heart transplanted from the same organ donor, and (3) the induction of acquired tolerance prevents the development of CAV.
These findings in a preclinical system establish the significance of antigen-dependent mechanisms in the pathogenesis of CAV and underscore the importance of achieving tolerance in clinical transplantation.
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