Breast cancer linked to obesity, finds study on rats

The study, which reflects the prowess of NIN in developing efficient animal models, throws light on the all-important link between obesity and the onset and development of breast cancer.

Hyderabad: In a groundbreaking collaborative research, scientists at the Hyderabad-based National Institute of Nutrition (NIN) developed a colony of unique spontaneous mutant obese rats and employed the animal models to demonstrate how obesity accelerates the onset and development of breast cancer. In the study published in the prestigious International Journal of Molecular Sciences (July, 2023), NIN researchers collaborated with their counterparts in other reputed research institutions, to demonstrate that breast cancer and its development happens faster in obese rats than leaner rats.

The study, which reflects the prowess of NIN in developing efficient animal models, throws light on the all-important link between obesity and the onset and development of breast cancer. The researchers developed obese rat models with Impaired Glucose Tolerance (IGT), which means the blood sugar levels in them were elevated but not high enough to diagnose diabetes.

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To initiate the tumour in the animal models, the researchers administered DMBA, an immunosuppressor that is a widely used carcinogen in research labs involved in cancer research. “The onset of breast tumours occurred earlier in obese rats administered with DMBA than in the lean rats with DMBA. The onset of tumour development in obese rats was observed after the 9th week of DMBA administration, whereas it was observed after the 26th week in counter-lean rats,” the study said.

After 32 weeks of administering the immunosuppressor, 62 per cent of the mutant obese rats developed mammary tumours while only 21 per cent of the lean animals developed breast tumours. On average, it took 119 days for the tumour to develop in obese rats while it took 211 days in the lean rats.

The research concluded that mutant obese rats served as an excellent model for studying the influence of obesity and impaired glucose tolerance on the progression of chronic diseases, particularly breast cancer. Obesity and IGT facilitates cancer development by inhibiting apoptosis (biological process of programmed cell death) and promoting cell proliferation, the study said.

Consequently, tumour development and progression were significantly elevated in obese rats. These findings emphasise the importance of understanding the relationship between obesity and breast cancer in order to develop effective strategies for prevention and treatment. The NIN researchers who were part of the study included Dr G Bhanunprakash Reddy, Kallamadi Prathap Reddy, Deepshikha Esari and Utkarsh Reddy Addi and P Uday Kumar while R Kesavan is a senior scientist from UT Southwestern Medical Centre, Texas, US and Siddavaram Nagini is a senior researcher from department of biochemistry, Annamalai University.