Salmonella fights cancer17th August 2010
The salmonella bacterium is useful in fighting cancer, according to a joint US and Italian study.
Researchers from the two countries found that salmonella helped the body to fight the deadliest form of skin cancer, when it was allowed to infect tumour cells.
Experts were already aware that Salmonella typhirmurium, which causes diarrhoea and is related to E coli, helped the immune system to recognise malignant melanoma.
Researchers in the recent study discovered the mechanism by which salmonella does this, showing that there may be innovative new vaccines for many types of cancer.
Tumour biologist Meenhard Herlyn of the Wistar Institute in Philadelphia, who was not involved in the recent study, said that salmonella treatment may work in combination with other therapies to improve cancer survival rates.
She said that, however, melanoma was probably too complex for doctors to hope for a complete cure based on the recent finding.
When the researchers injected the bacterium into mouse tumours, the tumours shrank.
Other tumours, in other parts of the body, also shrank.
In further experiments, the researchers showed that the process which caused the tumours to shrink relied on a protein channel known as connexin 43 (Cx43), also known as 43kDa, GJA1, and ODDD.
Cx43 is what is known as a 'connexin gap junction', and found in several types of cells in the body.
The highest number of cells with Cx43 is in the human heart, where researchers believe it plays a crucial role.
Cx43 also plays a pivotal role in labour contractions.
When Cx43 helps cells fight cancer, it does so by forming 'gap junctions' between cells, allowing them to share information about the immune system.
When salmonella was introduced into mouse tumour cells, the presence of the bacterium caused an increase in Cx43, which in turn allowed the immune system to begin processing the tumours.
The immune cells involved in the process, which are also known as dendritic cells, passed the processed bits of tumour material to other parts of the immune system, in a coordinated manner.
As a result, the body's immune system began to process multiple, separate tumours in the bodies of the mice, since the growths bore the same signature.
Lead author Maria Rescigno, of the European Institute of Oncology in Milan, said that scientists now had a 'gun' to use against tumours.
She said that doctors would soon be able to induce the immune system to fight cancers that all bore the same tumour-specific 'fingerprint'.
The Italian research team is interested in applying the technique in several ways.
First, they want to try replicating their results in human cancer patients.
They also want to see if they can broaden their approach to other types of cancers.
As a treatment, the process would probably require doctors to extract some cells from one of the patient's tumours, mix the tumour cells with salmonella, and inject the salmonella back into the patient's body.
Rescigno said that, to this end, she was already in the process of applying for authorisation from the Italian ministry of health.
She said that she and her team hoped that, by May or June 2011, a protocol using salmonella to activate Cx43 would already be well-established in cancer clinics.
Researchers currently believe that susceptibility to malignant melanoma is caused by both genetic and environmental factors.
Once this deadly type of skin cancer has spread to other organs in the body, people's rate of survival becomes quite low (below 15%).
Currently, there is no cure for melanoma, which uses a simple but effective technique to hide itself from the body's immune system.
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Title: Salmonella fights cancer
Author: Luisetta Mudie
Article Id: 15773
Date Added: 17th Aug 2010