Tag Archives: enzyme

Breast cancer enzyme discovered

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University of Minnesota researchers have uncovered a human enzyme responsible for causing DNA mutations found in the majority of breast cancers.

The discovery of this enzyme – called APOBEC3B – may change the way breast cancer is diagnosed and treated.

The findings came from a team of researchers led by Reuben Harris, Ph.D., associate professor of biochemistry, molecular biology and biophysics and also a researcher at the Masonic Cancer Center, University of Minnesota.

“We strongly believe this discovery will change the way mutations in cancer are viewed and, hopefully, it will allow cancer researchers to develop new treatments approaches that can prevent these mutations before they become harmful,” said Harris.

Harris’ quest to learn more about mutations in cancer initially began with HIV research. This previous work by Harris’ lab and others indicated that APOBEC3B and related enzymes function normally to protect from infectious viruses like HIV-1.

During these studies, Harris’ team developed specific tests to quantify the expression of each of the seven APOBEC3 genes, including APOBEC3B.

Harris and his team were able to apply these tests to the problem of mutation in breast cancer, showing only APOBEC3B is over-expressed in patients’ breast cancer cell lines and tumors.

Breast cancer

Breast cancer

“DNA mutations are absolutely essential for cancer development. Our experiments showed the APOBEC3B enzyme causes mutations in the genome of breast cancer cells. From this, we were able to reasonably conclude that the APOBEC3B is a key influencer in breast cancer,” said Harris.


However, Harris pointed out that APOBEC3B appears to be a biological “double-edged sword.” It protects some cells from viruses such as HIV-1 yet produces mutations giving rise to cancer in others.

Harris stresses the need for additional research. If further studies confirm that high APOBEC3B levels indicate the early presence of breast cancer, a simple blood test could be a strategy for early detection.

Another goal for Harris is finding a way to block APOBEC3B from causing mutation, just as sunscreen prevents sun from causing mutations leading to melanoma. His collaborative HIV studies are already pointing toward such drug possibilities.

Seaweed may fight tooth decay

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Microbes found on seaweed could provide an unexpected weapon in the fight against tooth decay, scientists have said.

They used an enzyme isolated from the marine bacterium Bacillus licheniformis which they were originally researching for cleaning ships’ hulls.

Instead, the Newcastle University team will tell the Society for Applied Microbiology Summer Conference that it could have a range of medical applications, including teeth cleaning.

While toothpastes are effective, there are still hard-to-reach areas between teeth where the bacteria in plaque can erode enamel, causing cavities.

Dr Nicholas Jakubovics of Newcastle University’s School of Dental Sciences believes better products offering more effective treatment can be made using the enzyme.

He said: “Plaque on your teeth is made up of bacteria which join together to colonise an area in a bid to push out any potential competitors.

“Traditional toothpastes work by scrubbing off the plaque containing the bacteria – but that’s not always effective – which is why people who religiously clean their teeth can still develop cavities.

Seaweed

Seaweed

“Work in a test tube has shown that this enzyme can cut through the plaque or layer of bacteria and we want to harness this power into a paste, mouthwash or denture cleaning solution.”

When threatened, bacteria shield themselves in a slimy protective barrier known as a biofilm.

It is made up of bacteria held together by a web of extracellular DNA which binds the bacteria to each other and to a solid surface – in this case in the plaque around the teeth and gums.


The biofilm protects the bacteria from attack by brushing, chemicals or even antibiotics.

But after studying Bacillus licheniformis, which is found on the surface of seaweed, Newcastle University scientists found that when the bacteria want to move on, they release an enzyme which breaks down the external DNA. That breaks up the biofilm and releases the bacteria from the web.

Professor Burgess, who led the research, said: “It’s an amazing phenomenon. The enzyme breaks up and removes the bacteria present in plaque and importantly, it can prevent the build up of plaque too.

“When I initially began researching how to break down these layers of bacteria, I was interested in how we could keep the hulls of ships clear but we soon realised that the mechanism we had discovered had much wider uses.

“If we can contain it within a toothpaste we would be creating a product which could prevent tooth decay.

“This is just one of the uses we are developing for the enzyme as it has huge potential such as in helping keep clean medical implants such as artificial hips and speech valves which also suffer from biofilm infection.”

The team will now look to collaborate with industry to carry out more tests and product development.