image: a small molecule induces the formation of Z-DNA in tumors to activate an inflammatory pathway of cell death that is expressed in the cells that support the growth of the cancer cell. The resulting immune response is specific for mutant proteins expressed by cancer cells. Tumor destruction is further enhanced by the infusion of an anti-PD-1 antibody that neutralizes the cancer cell’s ability to inhibit the responding immune cells. see more
Credit: Alan Herbert
In an article in Nature today, an international group of scientists has discovered a new way to kill hard to treat cancers. These tumors are resistant to current immunotherapies, including those that use Nobel Prize-winning checkpoint blocking antibodies.
The approach explodes Z-DNA. Instead of turning right like Watson and Crick B-DNA, Z-DNA has a left turn. A role of Z-DNA is to regulate the immune response to viruses. The answer involves two proteins that specifically recognize Z-DNA, AADR1 and ZBP1. They do this through a Zα domain that binds to the structure of Z DNA with high affinity. The Zα domain was originally discovered by Dr. Alan Herbert of InsideOutBio, a communicating author of the document. The ADAR1 Zα domain deactivates the immune response against oneself, while the other ZBP1 Zα activates pathways that kill virus-infected cells, as Dr. Sid Balachandran, the other author communicating the document. Interactions between ADAR1 and ZBP1 determine whether a tumor cell lives or dies.
Both Zα proteins are induced during interferon inflammation. They are not usually present in normal cells. Both proteins are also expressed in tumors, especially in normal cells called fibroblasts that are forced by cancer cells to support their growth. Tumors typically rely on ADAR1 to suppress cell death pathways that would otherwise kill the tumor.
The team found a small molecule that could prevent the suppression of ADAR1 and directly trigger the death of tumor cells by ZBP1. The drug acts independently of the mutation that causes the cancer. The induced form of cell death is highly immunogenic. The response destroys the fibroblasts that support tumor growth. In doing so, the drug improves the effectiveness of immunotherapy by blocking the antibody at the PD-1-targeted control point. The drug is a member of the curate family and was introduced to the clinic for another reason. The compound has been shown to be safe in Phase I trials, but still requires further research to confirm its clinical use along with anti-PD1 provides a benefit in the treatment of cancers.
Dr. Herbert of InsideOutBio says: “This result is the work of a highly collaborative team. It is a good milestone in our understanding of how alternative DNA conformations, such as Z-DNA, play a role. The paper shows how basic research can lead to new and unexpected therapies. These findings validated a biological role for Z DNA, and work has now led us to a new therapeutic approach to the treatment of cancer. they were widely rejected by the scientific community as of little biological importance and the subsequent work was not classified as worthy of funding by the National Institutes of Health’s peer review panels. This is possible thanks to the collaboration of the Fox Chase Cancer Center team led by Dr. Balachandran and the computer scientists of the Higher School of Economics of Dra. Poptsova, with the help of Dr. Walkley of the University of Melbourne, Dr. Xu forms Miyazaki University and Dr. St. Thomas Children’s Hospital Jude. It’s a testament to the times that this collaboration was successful, although I haven’t met any of the others in person. “
Z-DNA is formed in normal cells by sequences called flip-flops that, under physiological conditions, can rotate reversibly to the shape of the left hand. The structure was accidentally discovered in the first synthetic crystal ever solved by X-ray crystallography. There are other kinds of flip-flops and they are also very likely to play an important role in biology. Flippoons are highly dynamic structures that have been difficult to study because they are difficult to determine their exact conformation within cells. Dr. Herbert says that “It is similar to other highly dynamic systems in physics where the flipon conformation can only be found by direct measurement, but only if the act of measuring does not skew the result.”
InsideOutBio is a privately funded biotechnology company in its early stages that develops therapeutics for the treatment of cancer.
Research method
Experimental study
Research topic
Animals
Article title
ADAR1 masks the immunotherapeutic promise of ZBP1-induced necroptosis cancer
Date of publication of the article
May 25, 2022
IOC statement
The Fox Chase Cancer Center has filed a provisional patent application “Combination of Curexins and Inhibitors of the Immune Control Point for the Treatment of Cancer.”
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