Wednesday, June 20, 2012

Role of the Amino Acid Glycine in Cancer Cell Growth

One of the main and more ominous characteristic of cancer cells is their capacity to grow beyond the ordinary controls that limit cell proliferation in normal tissues.  This accelerated growth ultimately leads to metastasis – the spread of cancerous cells to surrounding tissues from the tissue of origin.  It is uncontrolled metastasis that ultimately leads to the death of the patient in the terminal stage of the disease.

It has been clearly established that cancer is the result of genetic mutation that gives transformed cells a definitive proliferative advantage over normal cells. Given this property common to all cancers, it would be efficacious to understand the mechanism through which this accelerated growth operates.  It has long been suspected that in cancer cells, key metabolic pathways have been altered in such a way as to accelerate cell division beyond normal limits.  This process is, however, poorly understood.

Through the laborious efforts of Dr. Mohit Jain and colleagues at the Broad Institute in Cambridge MA and at the Department of Systems Biology at Harvard Medical School, Boston, MA, a clearer understanding of the metabolic characteristics of rapidly growing cancer cells has emerged.

This group has painstakingly characterized the cell chemistry of 219 known metabolites from a panel of 60 well established primary human cancers in cell culture that reflect nine well known cancers and tumor types.  This was accomplished using highly sophisticated analytical tools involving liquid chromatography and tandem mass spectrometry.

Interestingly, from this data, it was discovered that the consumption of the amino acid glycine demonstrated a statistically relevant and significant correlation with cancer cell proliferation.  Glycine is an amino acid – amino acids are the chemical building blocks of proteins.  In addition, it is a non-essential amino acid i.e. the cells of the body are capable of synthesizing this amino and it is, therefore, not required in the human diet.

Furthermore, the glycine biosynthetic pathway found normally in the mitochondrion – a cell organelle that is responsible for energy production in cells – was shown to be the pathway of choice for the synthesis of glycine.  When the experimenters purposefully, blocked the synthesis of glycine by interfering with the mitochondrial synthetic pathway, the enhanced proliferation of the cancer cells studied was significantly impaired.

These findings uncover a previously unknown vulnerability of a wide range of known cancer types.  This discovery may prove to be highly significant as a strategy for the treatment of cancer. 

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