Hopes of a new strategy for inhibiting tumour cell growth
A team of scientists from Karolinska Institutet in and Harvard Medical School, US, have created a map of the metabolism of cancer cells. This has led to new discoveries about the amino acid glycine, suggesting new approaches to developing cancer treatments.
Several cancer therapeutics are based on preventing cancer cell metabolism, a process essential to cell division and growth in which nutrients are converted into energy and building blocks with the help of enzymes. Blocking certain enzymes obstructs this process, inhibiting cell division and the growth of cancer cells. Unfortunately, however, the drugs that do this also affect healthy cells, which in turn cause several adverse reactions.
"What we need to do is to identify enzymes that are important specifically for the metabolism of cancer cells, but not for normal cells that divide and grow," says Roland Nilsson, researcher at the computational medicine unit, Karolinska Institutet. "This would give us new, more effective ways of inhibiting cancer growth with fewer adverse reactions. If we're to achieve this, we need a better understanding of how cancer cell metabolism operates."
Using mass spectrometry, a sensitive analysis method that 'weighs' molecules, Dr Nilsson and his American colleagues have systematically measured the nutrients consumed by 60 different types of cancer cells.
The study, which is published in the scientific journal Science, reveals that rapidly growing cancer cells from various kinds of tumours consume the amino acid glycine. On the other hand, normal cells that grow and divide, such as white blood cells, consume no glycine at all. The researchers conclude that unlike cancer cells, normal cells can produce sufficient quantities of glycine on their own. They also noted high concentrations of the enzyme on which the cancer cells depend for their glycine supply in patients' cancer tumours, particularly in aggressive tumours, which are more fatal.
The researchers hope that glycine metabolism could be a weak spot of cancer cells. If so, blocking enzymes in glycine metabolism could help prevent certain cancer cells from growing and proliferating, with less impact on healthy cells than current treatments.
"But much remains to be done until we understand enough about how glycine metabolism operates in cancer cells for this to be exploited in a drug," says Dr Nilsson. "We also need to find substances that block these enzymes effectively and test whether they can prevent the growth of tumours without causing side-effects."
The study was financed with grants from the Knut and Alice Wallenberg Foundation, the Stockholm County Council, the National Institutes of Health, the Leukemia & Lymphoma Society and the Nestlé Research Center.
Metabolite profiling identifies a key role for glycine in rapid cancer cell proliferation.
Science 2012 May;336(6084):1040-4