07 September 2010

Cancer treatment without side effects: selective my-RNA therapy

The main difficulty in the treatment of cancer is that the disease "cancer" does not exist. Even with an absolutely identical diagnosis, cell malignancy in each individual case may have different mechanisms, and a drug that helps one patient well may be useless for his neighbor on the ward.

Secondly, there are no anti-cancer drugs without side effects. For example, drugs that suppress the division of tumor cells also act on healthy cells, primarily in fast–growing tissues, which leads to a violation of hematopoietic function, damage to cells of the intestinal mucosa, hair loss, etc.

One of the most promising directions in the search for a way to destroy only malignant cells without damaging healthy ones is the creation of drugs based on small interfering RNAs. The press service of the US National Science Foundation (NSF) recently reported on the successful trials of one of these drugs.

Niles Pierce from the California Institute of Technology, one of the authors of the work, the results of which are to be published in the September 6 issue of PNAS (S. Venkataraman, R.M. Dirks, C.T. Ueda, and N.A. Pierce, Selective cell death mediated by small conditional RNAs), compares DNA with a computer hard disk, on which information is stored permanently, and matrix, or informational, RNA – with RAM, transmitting information about the structure of proteins to effectors – ribosomes. Small RNAs play the role of regulators of the transmission of this information. Defects in the genes that lead to the appearance of a tumor are reflected in the corresponding matrix RNAs, which can serve as cancer markers that distinguish cancer cells from healthy ones.

Pierce and his colleagues used a combination of two mi-RNAs.

The first one changes its spatial structure when encountering tumor RNA markers, which triggers the polymerization process of the second mi-RNA: the molecules of the first mi-RNA, connecting in pairs, form "latches" that, when meeting the ends of short molecules of the second mi-RNA, connect them into long chains.

The body's immune system takes such polymers for viral RNA – and destroys the "infected" cells.

In healthy cells, in which defective genes and, accordingly, an RNA marker are absent, such a "double-action mine" does not work.

Using cell cultures of several types of tumors (brain, prostate and bone cells), scientists have shown that their method allows 20-100 times to reduce the number of malignant cells without affecting healthy ones.

The need to isolate personal RNA markers for a particular patient's tumor is fully compensated by almost complete confidence in the absence of side effects. However, from successful in vitro trials to the introduction of selective RNA therapy into the clinic, even in an ideal case, many years of preclinical and clinical research are needed.

A. Chubenko
Portal "Eternal youth" http://vechnayamolodost.ru According to ScienceDaily: Conditional Small RNA Molecules Can Kill Cancer Cells and Leave Healthy Cells Alone07.09.2010

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