The Smoothened receptor (SMO) mediates signal transduction in the hedgehog pathway, which is implicated in normal development and carcinogenesis. SMO antagonists can suppress the growth of some ...tumours; however, mutations at SMO have been found to abolish their antitumour effects, a phenomenon known as chemoresistance. Here we report three crystal structures of human SMO bound to the antagonists SANT1 and Anta XV, and the agonist, SAG1.5, at 2.6-2.8 Å resolution. The long and narrow cavity in the transmembrane domain of SMO harbours multiple ligand binding sites, where SANT1 binds at a deeper site as compared with other ligands. Distinct interactions at D473(6.54f) elucidated the structural basis for the differential effects of chemoresistance mutations on SMO antagonists. The agonist SAG1.5 induces a conformational rearrangement of the binding pocket residues, which could contribute to SMO activation. Collectively, these studies reveal the structural basis for the modulation of SMO by small molecules.
Abstract
Merkel cell carcinoma (MCC) is an aggressive neuroendocrine skin cancer with limited treatment options. Currently two immunotherapies are approved for the treatment of MCC, the PD-L1 ...inhibitor avelumab and the PD-1 inhibitor pembrolizumab. Unfortunately, these treatments only have durable benefit for less than half of patients that can be treated with immunotherapy. Therefore, new and effective treatments are needed for MCC. To address this, we conducted a high-throughput drug screening of ~4,000 small molecules. Our drug screen identified disulfiram (DSF), an aldehyde dehydrogenase inhibitor used in the treatment of alcoholism, as an agent that selectively reduced MCC cell viability. Recent studies suggest that DSF complexed with copper can have anti-cancer effects. Consistent with this, the addition copper at physiological levels increased the potency of DSF in MCC cells lines. Next, we demonstrated that disulfiram combined with copper synergized with the topoisomerase II inhibitor etoposide, lowering the effective dose of etoposide required to reduce MCC cell viability. Mechanistically, combining DSF, copper and etoposide was cytotoxic but did not induce apoptosis in MCC cell lines. This combination increased the formation of double stranded DNA breaks while disulfiram plus copper induced autophagy, which could mechanistically be an indication of immunogenic cell death signaling. Taken together, our data suggest that disulfiram combined with copper and etoposide could be repurposed for the effective treatment of advanced MCC. One strong advantage of this combination is that all agents can be given orally and at dosages with minimal adverse effects.
Citation Format: Natasha Tremayne Hill, Tara Gelb, Dan Urban, Tyler Kellenberger, Matthew Hall, Isaac Brownell. Disulfiram plus copper synergizes with etoposide for the treatment of Merkel cell carcinoma abstract. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 575.
The Smoothened receptor (SMO) mediates signal transduction in the hedgehog pathway, which is implicated in normal development and carcinogenesis. SMO antagonists can suppress the growth of some ...tumors; however, mutations at SMO have been found to abolish their anti-tumor effects, a phenomenon known as chemoresistance. Here we report three crystal structures of human SMO bound to the antagonists SANT1 and Anta XV, and the agonist, SAG1.5, at 2.6–2.8Å resolution. The long and narrow cavity in the transmembrane domain of SMO harbors multiple ligand binding sites, where SANT1 binds at a deeper site as compared with other ligands. Distinct interactions at D473
6.55
elucidated the structural basis for the differential effects of chemoresistance mutations on SMO antagonists. The agonist SAG1.5 induces a conformational rearrangement of the binding pocket residues, which could contribute to SMO activation. Collectively, these studies reveal the structural basis for the modulation of SMO by small molecules.
This thesis describes election campaigns of the Communist Party of Czechoslovakia in interwar Czechoslovakia. The author examines the development of Communist electoral propaganda and agitation ...before parliamentary elections in 1925, 1929 and the 1935. This paper deals mainly with the changing attitudes of the Communist Party to the political system and the other political parties.
Employers should be very rigorous when choosing employees to make sure they're motivated, then keep them engaged by offering team-based incentives and chances to advance, said Bob Orzechowski, past ...president of the Berks County Chapter of the Society for Human Resource Management.
June 27--The Supreme Court's decisions on same-sex marriage were celebrated as a victory Wednesday by local gay-rights advocates, while opponents were relieved the rulings don't immediately impact ...Pennsylvania law. ...though the court didn't remove gay marriage bans in Pennsylvania and about three dozen other states, it left in place a trial court's declaration that California's Proposition 8, which outlawed same-sex marriage, is unconstitutional, clearing the way for the resumption of gay marriage in that state. "Same-sex couples are now closer to equal rights," said Jerry Schearer, a Kutztown University administrator who advises Allies, the school's gay rights student group.
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