Anthrax and cancer
Anthrax is a serious infectious disease caused by the bacterium Bacillus anthracis, known for its ability to evade the immune system and produce a lethal toxin. Traditionally associated with severe health risks, anthrax toxin is now being explored as a potential tool in targeted cancer therapies, particularly for drug-resistant tumors like melanoma, breast cancer, and colon cancer. The toxin's mechanism involves three proteins that, when combined, can induce cell death specifically in cancer cells without significantly harming normal cells, a distinct advantage over traditional chemotherapy. Research indicates that bioengineered forms of anthrax toxin may effectively destroy tumor cells and inhibit the formation of blood vessels that supply nutrients to tumors. Initial studies, including those involving dogs with bladder cancer, have shown promising results, suggesting that this approach could eventually be adapted for human use. However, the potential side effects of anthrax-based therapies remain unknown, and further research will be essential to establish safety and efficacy. As this area of study progresses, it holds both challenges and hope for advancing cancer treatment strategies.
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Anthrax and cancer
DEFINITION: Anthrax (from the Greek word for coal, anthrako, for the characteristic black skin lesions seen in cutaneous anthrax) is an often fatal infectious disease caused by the bacterium Bacillus anthracis. This bacterium is particularly virulent because it is surrounded by a coating that prevents the immune system from killing it. The bacterium also secretes a toxin lethal to certain white blood cells (macrophages). Anthrax toxin, the key virulent component of B. anthracis, is currently being studied for use as targeted biological therapy for drug-resistant tumors.
B. anthracis is sensitive to a number of antibiotics, including doxicyclin, and fluoroquinolones. Most people, however, do not have preexisting immunity to anthrax because it is not a routine immunization with the exception of some US military personnel.
Cancers treated: Melanoma, breast cancer, colon cancer
Delivery routes: Injection
How this substance works: Anthrax infection begins when the spores of the bacteria are inhaled or come into contact with the skin. The primary virulent factor is the anthrax toxin produced by the bacteria. The toxin is activated by furin, a protein found in all living cells. Anthrax toxin may be genetically engineered to eschew furin and instead target only cells with high levels of urokinase, a protein produced prolifically by human tumor cells.
The anthrax toxin contains three proteins that are innocuous when separate but work together to create a lethal environment for cells. Protective antigen (PA) is an anthrax protein that adheres to a host cell surface and bores a hole into it. The other two proteins released by the bacteria, edema factor (EF) and lethal factor (LF), are too large to penetrate the outside of the cell unless PA guides them inside. For cellular intoxication, PA is always needed. Once inside the cell, only EF or LF is needed to speed up the reactions that ultimately render inactive parts of the immune system and finally to cell suicide (apoptosis). The term “anthrax lethal toxin,” when used in cancer therapy research, refers to the combination of PA and LF. PA is the substance in the anthrax vaccine.
Cancer researchers hope to harness the cellular suicide caused by the anthrax toxin to prevent tumors from growing and spreading. In animal studies, the toxin both destroyed tumor cells and prevented the vascularization of tumors. Tumors typically need several nutrients to grow, which vascularization helps provide. Bioengineered anthrax toxin has not been shown to damage deoxyribonucleic acid (DNA) or prevent cell growth in normal cells, which is common in traditional chemotherapy. In 2019, dogs suffering from bladder cancer were administered an anthrax toxin-derived agent. The dogs were administered the agent with a catheter. Initial results showed that tumors were shrunk by an average of 30%. The results showed the potential that treatments of this type could, in time, be made available for humans.
Side effects: The potential side effects of anthrax therapy are not yet known.
Bibliography
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