On-off switch with clues to blindness, cancer found

October 7th, 2008 - 10:52 am ICT by IANS  

Toronto, Oct 7 (IANS) Canadian researchers claim to have found an on-off switch that holds clues to cure for blindness, tumour and even cancer.Researchers at Montreal University, in collaboration with the Institut national de la santé et de la recherche médicale (INSERM) in France, said Monday that the on-off switch - called GPR 91 receptor in neurons - causes unchecked blood vessel growth that leads to vision loss.

The GPR 91 - or G protein-coupled receptor - functions as a detector of cell metabolism and is present in the kidney, liver, spleen, breast and blood vessels.

During their investigation of the molecular mechanisms that lead to blindness, the researchers found that the GPR91 receptor can lead to irregular blood vessel growth which is one of the main causes of vision loss.

The blindness includes retinopathy of prematurity in infants, diabetic retinopathy in adults (vision loss in up to 90 percent of diabetics) or age-related vision loss in seniors, the researchers said in a statement.

“We found that GPR91 is a master regulator of blood vessel growth, which upon enhanced activation leads to the unchecked and anarchic proliferation of vascular networks, which is the hallmark of retinopathies.

“This uncontrolled overgrowth can ultimately cause the retina to detach and a person to lose their sight,” the statement quoted study leader Mike Przemyslaw Sapieha as saying.

“With the identification of GPR91 as a key player in this disease process, we can move forward in designing treatments that block the receptor and consequently stop vision loss. Inhibition of GPR91 has a great therapeutic potential to halt these blinding diseases.”

According to the statement, the study also provides promise that the GPR91 receptor can preserve neurons which transmit information in the brain through chemical signals.

“Neurons are key sensors in retina oxygenation and serve as key players in the repair process of the retina,” said study director Sylvain Chemtob.

“Given the similarities between the retina and the brain, we can envisage applying our findings in retina to the brain. Activation of the GPR91 receptor could be beneficial in helping salvage neurons in damaged brain tissue in stroke or head injury victims,” he said.

The researchers also hinted at the possibility that interfering with the GPR91 receptor may be used to stop cancer growth.

“If you stop GPR91 from allowing blood vessels to expand and supply a tumour with nutrients and oxygen, one can significantly hamper growth of the cancer,” said Sapieha.

Researchers conducted investigations on GPR91 in animals. But since the receptor is also found in humans, they said it will soon be extended to human clinical investigations in three to fours years.

The findings appear in the online edition of Nature Medicine.

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