Dataset Information

Monitoring and characterizing soluble and membrane-bound ectonucleotidases CD73 and CD39.

ABSTRACT: The success of immunotherapy treatment in oncology ushered a new modality for treating a wide variety of cancers. However, lack of effect in some patients made it imperative to identify other pathways that are exploited by cancer cells to circumvent immune surveillance, and possibly synergize immune checkpoint treatment in those cases. It has been recently recognized that adenosine levels increase significantly in the tumor microenvironment and that adenosine/adenosine receptors play a powerful role as immunosuppressive and attenuating several effector T cell functions. The two main enzymes responsible for generating adenosine in the microenvironment are the ectonucleotidases CD39 and CD73, the former utilizes both ATP and ADP and produces AMP while the latter utilizes AMP and generates adenosine. Thus, these two enzymes combined are the major source for the bulk of adenosine produced in the microenvironment. They were shown to be validated targets in oncology leading to several clinical trials that include small molecules as well as antibodies, showing positive and encouraging results in the preclinical arena. Towards the development of novel drugs to target these enzymes, we have developed a platform that can be utilized to monitor the activities of both enzymes in vitro (biochemical) as well as in cells (cell based) assays. We have developed very sensitive and homogenous assays that enabled us to monitor the activity of both enzymes and demonstrate selectivity of known inhibitors as well as monoclonal antibodies. This should speed up screening for novel inhibitors that might lead to more effective cancer therapy.

SUBMITTER: Goueli SA

PROVIDER: S-EPMC6814236 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Monitoring and characterizing soluble and membrane-bound ectonucleotidases CD73 and CD39.

Goueli Said A SA Hsiao Kevin K

PloS one 20191025 10

The success of immunotherapy treatment in oncology ushered a new modality for treating a wide variety of cancers. However, lack of effect in some patients made it imperative to identify other pathways that are exploited by cancer cells to circumvent immune surveillance, and possibly synergize immune checkpoint treatment in those cases. It has been recently recognized that adenosine levels increase significantly in the tumor microenvironment and that adenosine/adenosine receptors play a powerful ...[more]

PMID: 31652269

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Project description:The superfamily of cytochrome P450s forms a large class of heme monooxygenases with more than 13,000 enzymes represented in organisms from all biological kingdoms. Despite impressive variability in sizes, sequences, location, and function, all cytochrome P450s from various organisms have very similar tertiary structures within the same fold. Here we show that systematic comparison of all available X-ray structures of cytochrome P450s reveals the presence of two distinct structural classes of cytochrome P450s. For all membrane bound enzymes, except the CYP51 family, the beta-domain and the A-propionate heme side chain are shifted towards the proximal side of the heme plane, which may result in an increase of the volume of the substrate binding pocket and an opening of a potential channel for the substrate access and/or product escape directly into the membrane. This structural feature is also observed in several soluble cytochrome P450s, such as CYP108, CYP151, and CYP158A2, which catalyze transformations of bulky substrates. Alternatively, both beta-domains and the A-propionate side chains in the soluble isozymes extend towards the distal site of the heme. This difference between the structures of soluble and membrane bound cytochrome P450s can be rationalized through the presence of several amino acid inserts in the latter class which are involved in direct interactions with the membrane, namely the F'- and G'-helices. Molecular dynamics using the most abundant human cytochrome P450, CYP3A4, incorporated into a model POPC bilayer reveals the facile conservation of a substrate access channel, directed into the membrane between the B-C loop and the beta domain, and the closure of the peripheral substrate access channel directed through the B-C loop. This is in contrast to the case when the same simulation is run in buffer, where no such channel closing occurs. Taken together, these results reveal a key structural difference between membrane bound and soluble cytochrome P450s with important functional implications induced by the lipid bilayer.

Dataset Information

Monitoring and characterizing soluble and membrane-bound ectonucleotidases CD73 and CD39.

Publications

Monitoring and characterizing soluble and membrane-bound ectonucleotidases CD73 and CD39.

Similar Datasets

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