Whereas genome sequencing defines the genetic potential of an
organism, transcript sequencing defines the utilization of this
potential and links the genome with most areas of biology. To
exploit the information within the human genome in the fight against
cancer, we have deposited some two million expressed sequence
tags (ESTs) from human tumors and their corresponding normal tissues
in the public databases. The data currently define approximately
23,500 genes, of which only approximately 1,250 are still represented
only by ESTs. Examination of the EST coverage of known cancer-related
(CR) genes reveals that <1% do not have corresponding ESTs, indicating
that the representation of genes associated with commonly studied
tumors is high. The careful recording of the origin of all ESTs
we have produced has enabled detailed definition of where the
genes they represent are expressed in the human body. More than
100,000 ESTs are available for seven tissues, indicating a surprising
variability of gene usage that has led to the discovery of a significant
number of genes with restricted expression, and that may thus
be therapeutically useful. The ESTs also reveal novel nonsynonymous
germline variants (although the one-pass nature of the data necessitates
careful validation) and many alternatively spliced transcripts.
Although widely exploited by the scientific community, vindicating
our totally open source policy, the EST data generated still provide
extensive information that remains to be systematically explored,
and that may further facilitate progress toward both the understanding
and treatment of human cancers.