One of the major drawbacks of targeted cancer therapies is that cancers often become resistant to the drugs. Acute Lymphoblastic LeukemiaA cancer affecting the cells that develop into white or red blood cells. Both of these cell types originate from stem cells in bone marrow. Red blood cells function to carry oxygen to our tissues and the white cells (leukocytes) are part of our immune system. The cancerous cells often accumulate in the blood. (ALL) is a prime example. Drugs that block specific enzymes (kinases) in patients with this disease often fail due to the development of cancer cells that no longer respond to the drug.
New research, using human cancer cells in mice, has shown that cancer cells under attack by the kinaseAn enzyme that adds phosphate groups to another molecule. Many key proteins controlling gene expression are kinase targets. Addition of a phosphate group to a protein can alter the activity of the protein and are often used as molecular on/off switches. For example, the retinoblastoma tumor suppressor gene is 'off' when phosphate groups are added to the protein at specific locations. Removal of the phosphate groups turns the protein 'on'. Enzymes that remove phosphate groups are known as phosphatases. Note that all enzymes, regardless of function, end in ASE inhibitors often turn up a proteinOne of the four basic types of biomolecule. Proteins are polymers made up of strings of amino acids. Proteins serve many functions in organisms including transport of molecules, structure, cell adhesion and as signaling molecules such as hormones. Many transcription factors, including p53 and Rb are proteins. (BCL6) that causes them to be protected from the drug. When a second drug that blocks the activity of BCL6 was added, the cancer cells were rendered sensitive. In essense, drug resistance was blocked. The results indicate that other cancers also have targets that render them vulnerable to existing drugs.
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