In The Big League

Aspirins are being tested for their ability to 

combat cancer and Alzheimer's disease writes Biplab Das 

Since its debut in 1899, aspirin has gained popularity for being able to help avert a pending stroke. But this benefit comes at the cost of side effects like ulcers and kidney failure. Now, researchers have announced the discovery of new superaspirins, which not only lack the harmful side effects but also show promising results in stalling the progression of cancer and Alzheimer's disease. 

This finding stems from epidemiological studies, which showed a 45 per cent drop in deaths from colon cancer and less incidence of Alzheimer's disease in people regularly taking aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs) for arthritis or other conditions. 

Biochemist Raymond DuBois and cancer surgeon R. Daniel Beauchamp of Vanderbilt University in Nashville, Tennessee, were the first to discover NSAID's efficacy. They found colon tumours cells rich in COX-2 (cyclooxygenase 2), an enzyme blocked by aspirin and its cousins. 

Stephen Prescott of the University of Utah, Salt Lake City, accuses COX 2 of releasing free radicals when it generates hormones called prostaglandins. Free radicals armed with reactive oxygen ions cause harmful mutations turning a cell cancerous. And DuBois's team found other evidence to pinpoint COX-2's conspiracy. COX-2 produces stimuli needed to direct the growth of new blood vessels, which provide the tumour with nourishment necessary for its survival. 

In case of Alzheimer's, the role of COX 2 inhibitors is still hazy. According to some researchers, these drugs are good at safeguarding the nerve cells against inflammation caused by amyloid plaques, the protein deposits found in the brains of people with Alzheimer's. 

The drugs may check the population of free radicals, a possible suspect in Alzheimer's brain damage. In others' opinion, COX-2 is a part of nerve cell's communication system. So, inhibiting the enzyme might protect the nerve cells. 

Neuroscientist Nicolas Bazan and his colleagues at the Louisiana State University Medical Center in New Orleans have come up with more intriguing results. Monitoring injured nerve cells, he found nerve cells rich in COX 2 protein which speeds up apoptosis (controlled death of cells). Now, switching off the COX 2 gene, Bazan noticed reduced amount of COX 2 protein in cells, which decelerates apoptosis. But, researchers are yet to unearth the exact roles of COX 2 in Alzheimer's and cancer. 

Working in the same field at the American Health Foundation in Valhalla, New York, Bandaru Reddy and his colleagues have found celecoxib, a COX 2 inhibitor effective in reducing the number of tumours. 

When administered to rats, it also made the tumours less virulent. Reddy and his colleagues reported their findings in a recent issue of Cancer Research.

    January 25, 1999.