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A new factor in the fight against cancer

Protein discovery can help create more effective treatment for diabetic individuals with ovarian cancer

High blood sugar levels associated with diabetes have been shown to accelerate ovarian tumour growth— but a U of G researcher discovered a new transporter protein in ovarian cancer cells that could lead to improved cancer diagnosis and treatment.

Dr. Lisa Kellenberger, PhD graduate in the University of Guelph's Ontario Veterinary College.Dr. Lisa Kellenberger, a PhD graduate in the Ontario Veterinary College’s Biomedical Sciences Department, discovered that a class of proteins called sodium-glucose symporters (SGLTs) are expressed in ovarian tumours. SGLTs supply cancer cells with glucose (sugar) to aid in tumour growth and can now become the focus of slowing tumour progression for researchers.

Kellenberger and her team also discovered that diabetes speeds up the metabolism of ovarian cancer tumours. As blood-glucose levels rise, so does tumour size within mice and possibly humans. This is essential to pay attention to, according to Kellenberger, when treating diabetic individuals that will typically have four times the amount of sugar in their blood than the average person.

“I think it’s important for researchers to keep an open mind,” says Kellenberger. “You can’t count anything out – glucose transport in tumours was set in stone until we discovered a new transporter.”

 Until now, glucose transporters called GLUTs were assumed to be the only passage point for glucose to enter cancer cells. Kellenberger discovered that SGLTs move as much glucose into cancer cells as GLUTs.

This research provides new insight into ovarian cancer that can help researchers narrow their focus and help practitioners diagnose and treat patients more effectively, researchers say.

Typically, ovarian tumours are detected using magnetic resonance imaging (MRI) and positron emission tomography (PET) scans – patients drink a cocktail of glucose that has a fluorescent marker attached to it. The glucose becomes visible under scans, indicating the presence of tumours by unusually concentrated patches of fluorescent light. The tagged glucose will show where the body is using high amounts of glucose, which normally includes the brain, liver, and potentially, tumours. 

Unfortunately, the current method’s tagged glucose only interacts with GLUTs and not the newly discovered transporter, SGLTs. Because of this, doctors may only be able to see half of the glucose entering tumours, potentially concealing the tumour’s location in images.

“Now that we are aware of SGLTs, research can be put towards creating a new method that interacts with both GLUTs and SGLTs. This can lead to more accurate cancer tumour imaging.”

“An SGLT-specific version of tagged glucose could be created,” says Kellenberger.  “This would allow practitioners to see the full use of glucose by tumours when testing patients.”

Future studies will test several medications to reduce blood-sugar and the amount of glucose cancer cells absorb.

This research was performed in collaboration with supervisor Dr. Jim Petrik, and funded by the Canadian Institutes of Health Research and a Vanier Canada Graduate Research Scholarship.

The Ovarian Cancer Canada Walk of Hope takes place on September 10, 2017.
Learn more about the Guelph event, co-organized by University of Guelph biomedical sciences researcher Jim Petrik. #walkofhope

Article by Sydney Pearce, SPARK (Students Promoting Awareness of Research Knowledge.)