MicroRNA Signature for the Human Colonic Crypt Base Region is Predictive of Colon Cancer: Abstract No. LB-6 from AACR meeting 2006.

Most researchers use gene or protein "chips" to define cancer processes, but researchers at Thomas Jefferson University in Philadelphia took a novel
approach using a micro-RNA (miRNA) chip to help them understand how colon cancer develops. They found a distinct "signature" in the expression of
miRNAs that predicts colon cancer.
To discover which miRNAs are expressed in colon cancer, compared to normal colon tissue, researchers at Thomas Jefferson University in Philadelphia, used a microarray chip containing probes for most of the known miRNAs in human and mouse. The investigative team, led by Bruce Boman, M.D., Ph.D., director of Genetic and Preventive Medicine at Jefferson, used the array to first characterize the miRNA expression pattern in intestinal epithelium purified from normal colon tissue.

This epithelial inner lining of the colon contains about 50 million test-tube shaped crypts that line the colon. Colon cancer arises in these crypts, and
researchers believe that the cells of origin are the 10-20 immortal stem cells that reside at the bottom of each crypt. The job of these stem cells is to
replenish the entire lining of the colon that turns over every five days.

However, a mutation in these stem cells produces mutant daughter cells, disorganized tissue architecture, and increased proliferation of crypt cells,
which leads to development of colon tumors

RNA-i based technologies have gained popularity by addressing the ability to knockdown several genes at the same time. The reduction in protein translation may contribute to the target's physiological relevance. Another approach could be substractive hybridization (siRNA). I wonder if this method has ever been used by the research group in Philadelphia, to discover the miRNA involved in colon cancer?

Hi Sandy,

Subtractive hybridization is a labor-intensive technique. Screening with a gene array comparing healthy and cancerous tissue extracts produces the same information about differential expression with less steps.

It is interesting that you suggest that RNAi/siRNA techniques have gained popularity by addressing the ability to knockdown several genes at the same time. This non-specificity is usually considered a disadvantage of RNA interference over more selective knockdown techniques such as steric blocking antisense.

Best regards,

- Jon