The Faculty of Health and Medical Sciences at the University of Copenhagen recently discovered how a particular protein, Phosphoprotein phosphatase 2A (PP2A), inhibits tumor development in mice.  

Proteins are complex molecules in cells that are necessary for the function, structure, and regulation of the body's organs and tissues. Proteins have five primary functions: antibodies, enzymes, messengers, structural components, and transport or storage of atoms or small molecules. 

Professor Jakob Nilsson, from the Novo Nordisk Foundation Center for Protein Research, explained that PP2A is called a household protein as it can be commonly found in most places. Everything that lives with simple cells or complex cells contain PP2A. 

The PP2A Protein is also being studied by pharmaceutical companies as it is known to show unique patterns of kinase opposition, or simply, it is a tumor suppressor. Protein kinases are enzymes that induce change, switching active proteins into an inactive form. 

While there is still insufficient research on which specific types of proteins PP2A regulates to prevent cancer, results from the new data do gain more insight. 

Tumor Suppressor Proteins

Other tumor suppressor proteins include the retinoblastoma protein (pRb) and the p53 gene. Both regulate the cycling behavior of cells in a process called cell proliferation and growth are known as cell cycle progression. 

Rb has a vital part in regulation G1/S transition, which is the 'start' checkpoint which controls the production of starter kinase proteins. What follows is Rb's 'role in the functioning of normal and cancer stem cells,' as well as its effect on the 'energy metabolism of cancer cells.'

According to a study called Nanostructures for Cancer Therapy, P53 is a protein that can 'respond to hypoxia, DNA damage, and loss of normal cell contacts when activated,' as it mediates the growth and death of cells.

The same study notes, 'targeting p53-MDM2 interaction would be attractive in cancer therapy.'

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Battle Against ADAM17

Associate Professor Marie Kveiborg from the Biotech Research and Innovation Centre notes that what is new about their study is that they can show how the specific PP2A‐B56 'selects the phosphate groups that shall be removed from other proteins,' while it turns off the enzyme ADAM17. ADAM17 being switched off resulted in 'inhibition of tumor growth in mice.'

A disintegrin and metalloprotease domain 17 (ADAM17) is a protein-coding gene associated with diseases including inflammatory skin (psoriasis), inflammatory bowel disease (Crohn's disease), and breast cancer. The test mice were all injected with three variations of ADAM17 cells. 

On the day of injection, '4T1 A17wt, I762A, and LEE cells,' all ADAM17 variants, were given and the scientists monitored tumor growth through time. 

When they began observing how PP2A-B56 interacted with ADAM17, 'none of the mice injected with ADAM17 LEE cells reached tumor endpoint criteria, as opposed to ADAM17 wt or I762A injected mice, which exhibited only 50% survival by the end of the experiment.'

The newly discovered data on cancer research will hopefully develop into studies with human tumors, expressed by the researchers. The scientists concluded, 'the B56 inhibitor displays excellent specificity toward the PP2A‐B56 holoenzyme family.' As a result, scientists also want to make additional research to determine if PP2A also can regulate other proteins with its tumor suppressor function. 

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