Lung cancer, melanoma genomes decoded

By David Liu davidl at foodconsumer dot org

Lung cancer DNA decoded genetically

With a new DNA sequencing technique, researchers have decoded the entire genetic sequence of cancer cells from a patient who suffered small-cell lung cancer, according to a study report scheduled to appear in a future issue of the journal Nature.

The new genetic information can help understand how more than 60 carcinogens in cigarette smoke cause damage to human DNA in the lung leading to cancer-causing genetic mutations.

Dr. John Minna at UT Southwestern Medical Center and colleagues used a DNA technology called massively parallel sequencing to compare the DNA sequences of both lung cancer and normal or healthy cells from a patient for the differences.

The researchers discovered more than 23,000 mutations in the tumor cells and a new gene called CHD7 that is involved in lung cancer.  They estimated that every 15 cigarette smoked was associated with one mutation.

Melanoma genome contains 33,000 mutations

In another study published in the same issue of Nature, researchers from Wellcome Trust Sanger Institute found the melanoma genome contains more than 33,000 mutations.

Many of the mutations have something to do with exposure to ultraviolet light.  But the rest are not related to UV light.

The sequence shows the genome has its DNA repair system most active in gene regions to protect itself from damage while the protection is weak in the regions between genes.

The genomes of melanoma cells and normal cells were sequenced in the study more than 70 times to produce accurate data.

Research conducted in 2002 led to discovery of a mutation in one gene called BRAF which the researchers believe is important in driving development of melanoma.

The researchers said the finding of BRAF gene may lead to the development of novel therapies for clinical use in the future.

Genetic variant linked to lower risk of COPD

A study funded by the National Heart, Lung, and Blood Institute found a genetic variant was associated with a lowered risk of developing chronic obstructive pulmonary disease or COPD in children with asthma and adult smokers.

The study published online in the New England Journal of Medicine on Wednesday Dec 16 found a DNA single nucleotide polymorphism or SNP was linked to better preserved lung function in asthmatic children and former or current tobacco smokers.

Researchers went through data from seven studies of more than 8,300 children and adults and found the link between the SNP in MMP12, a gene that encodes matrix metalloproteinase 12 and better preserved lung function among participants.

They found that the adult participants with this SNP had a 35 percent reduced risk of onset of COPD.