Parasite Lurking in Cat Feces a Secret Weapon in Ovarian Cancer Treatment (U.S. Study)

A parasite found in cat feces may soon play a surprising role in fighting ovarian cancer.

　Toxoplasma is a protozoa found in cat dander, soil, and livestock meat, and about one-third of people are thought to be infected with toxoplasmosis at some point in their lives, but while the infection is unproblematic and unnoticeable in healthy people, it poses a risk to fetuses in the belly of pregnant women and people with weakened immune systems The

　According to a finding recently announced by U.S. researchers, a specific protein secreted by Toxoplasma has the effect of causing the immune system of mice to attack ovarian cancer that has already formed. This mechanism is attributed to the parasite's need to ensure its own survival without killing its host.

The use of the body's own immune system to eliminate cancer cells is one promising strategy in cancer treatment. However, due to the phenomenon of immune tolerance, the immune system sometimes has difficulty finding targets to attack.

　At Dartmouth Medical School in New Hampshire, USA, the researchers built on previous research showing that a safe, non-regenerative vaccine strain of Toxoplasma cured several types of solid tumors in mice.

　Once they identified the parasite proteins and immune pathways needed to break immune tolerance, they systematically deleted the genes for secreted effector proteins (molecules that the parasite injects into host cells to regulate the immune system). The modified parasite was then injected into mice with invasive ovarian cancer.

　The results showed that a specific protein secreted by Toxoplasma before and after it invades host cells regulates the development of an effective anti-tumor response in the host and raises the survival rate of mice with ovarian cancer.

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　According to David Bzik, Ph.D., who was involved in the study, tracking and understanding the host cell pathways manipulated by effector proteins secreted by Toxoplasma can reveal the underlying mechanisms that control immunity in response to infection. It will also identify relevant mechanisms in mammalian cells that will provide new targets for establishing more effective therapies for highly invasive solid tumors.

　The use of infectious organisms with the ability to break immune tolerance is a novel idea that may play an important role in future cancer therapies. Currently, researchers are also investigating ways to use Listeria monocytogenes to break immune tolerance in pancreatic tumors.

via:mirror/ translated & edited by hiroching