January 10, 2007
MicroRNAs Elevated In Pancreatic Cancers

Pancreatic cancer cells have very high levels of some microRNAs,

COLUMBUS , Ohio – A pattern of micro molecules can distinguish pancreatic cancer from normal and benign pancreatic tissue, new research suggests.

The study examined human pancreatic tumor tissue and compared it to nearby normal tissue and control tissue for levels of microRNA (miRNA). It identified about 100 different miRNAs that are present usually at very high levels in the tumor tissue compared with their levels in normal pancreatic tissue.

Each of these miRNA has a unique short sequence of RNA letters. RNA is like DNA except it delivers signals and instructions around inside of cells. That there are so many kinds of miRNAs at higher levels is useful for the development of anti-cancer treatments.

These researchers envision anti-cancer drugs aimed at the miRNAs which occur at higher concentrations in cancers.

“Our findings show that a number of miRNAs are present at very different levels in pancreatic cancer compared with benign tissue from the same patient or with normal pancreatic tissue,” says principal investigator Thomas D. Schmittgen, associate professor of pharmacy and a researcher with the Ohio State's Comprehensive Cancer Center.

“Most are present at much higher levels, which suggests that developing drugs to inhibit them might offer a new way to treat pancreatic cancer. It also means that a test based on miRNA levels might help diagnose pancreatic cancer.”

I see a more sophisticated way to use this information to develop anti-cancer therapies: Develop gene therapies that would go into cells in organs which have cancer cells. The gene therapies would have sequences that match with the miRNA sequences involved in cancer. If enough miRNA sequences match with corresponding gene sequence DNA segments this binding could be used to activate the gene therapy in a cell to kill that cell.

To put it another way: Develop a gene therapy that acts like a computer program that activates in the presence of genetic signals that indicate cancer. This would allow far greater selectivity in killing of cancer cells without killing normal tissue.

Out of about 470 miRNAs currently known these researchers measured the levels of 225 of them. Likely other miRNAs both known and yet to be discovered would help to improve the accuracy of this method of cancer identification.

For this study, the researchers used a technique developed by Schmittgen and a group of colleagues in 2004 to measure miRNA in small tissue samples. The method is based on a technology called real-time PCR profiling, which is highly sensitive and requires very small amounts of tissue, Schmittgen says.

The researchers used the method to compare the levels of 225 miRNAs in samples of pancreatic tumors from patients with adjacent normal tissue, normal pancreatic tissue and nine pancreatic cancer cell lines.

Computer analysis of the data identified a pattern of miRNAs that were present at increased or decreased levels in pancreatic tumor tissue compared with normal tissue. The analysis correctly identified 28 out of 28 pancreatic tumors, 11 of 15 adjacent benign tissues and six of six normal tissues.

Levels of some miRNAs were increased by more than 30- and 50-fold, with a few showing decreased levels of eight- to 15-fold.

We need methods to deliver gene therapy into all the cells in an organ. With such a capability we could periodically get gene therapy that'd wipe out precancerous cells before they even become full blown cancers.

Share |      Randall Parker, 2007 January 10 11:12 PM  Biotech Cancer

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