Cancer Cell Genome Sequence Reveals New Culprits

Many candidate genes not previously linked to cancer

THURSDAY, Sept. 7 (HealthDay News) -- Large-scale sequencing of human tumor cell genes has uncovered a set of "candidate cancer" genes -- many of which have never been linked to cancer -- that are frequently mutated in breast and colorectal tumors, according to a report published online Sept. 7 in Science.

In the study, Tobias Sjoblom, Ph.D., of the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins in Baltimore, and colleagues sequenced a highly curated set of 13,023 genes in 11 breast and 11 colorectal tumors to begin a systematic analysis of genetic changes that occur in cancer cells. Both tumor types contribute to a significant proportion of worldwide cancer burden.

After sorting through the mutations to determine which had a high probability of being functional in cancer, the group found many expected mutations but also a large number of unexpected mutations in genes not previously linked to cancer. The genetic changes were different between the two tumor types and were even different between tumors obtained from the same tissue. Overall, they identified 189 gene mutations, or about 11 per tumor, that occurred with significant frequency. Although tumors accumulated about 90 mutant genes, not all played a role in cancer growth and metastasis.

"These data define the genetic landscape of two human cancer types, provide new targets for diagnostic and therapeutic intervention, and open fertile avenues for basic research in tumor biology," the authors write.

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