Drug to Treat Accelerated Aging in Phase I Trial

Prodarsan is a combination of small protein molecules devised by Pharming NV[PHGUF.PK] for treatment of premature aging including Cockayne's Syndrome.

Leiden, The Netherlands, April 23, 2008. Biotech company Pharming Group NV (Pharming) (NYSE Euronext: PHARM) announced today that its wholly owned subsidiary DNage has started a Phase I clinical study to evaluate the pharmacokinetics and tolerability of Prodarsan(R) in humans.

Premature ageing, the primary target of Prodarsan(R), is a group of rare genetic diseases which manifests itself in several forms that are genetically and clinically similar although not identical. Dependent on the specific form of the disease, patients have a strongly reduced life expectancy and exhibit many ageing-related diseases early on in their lives. There is currently no effective therapy available for these patients.

Pharming has demonstrated that Prodarsan(R) as an oral, liquid formulation has significant effects in animal models for Cockayne Syndrome (CS). CS is one of the more common forms of premature ageing and is characterized, amongst others, by growth failure, mental retardation, eye abnormalities and a reduced life expectancy. The positive effects of Prodarsan(R) in preclinical testing on life expectancy in general and more specifically on the eye abnormalities are promising for further development of the product and its testing in humans.

The Phase I trial that is now being conducted consists of a combined single and multiple dose escalating clinical study in healthy volunteers. By studying the pharmacokinetics and tolerability of Prodarsan(R) and the effects of food intake on the absorption and elimination of the product, an oral dosing scheme will be determined that targets the pharmacological effective concentration range effectively. It is expected that following a successful completion of this trial the first clinical studies in patients will start later in 2008. Source

Prodarsan's proposed mechanism of action is via the DNA repair mechanism of the cell.

CKN1 is caused by a defect in the Cockayne syndrome type A gene (CSA or ERCC8) located on chromosome 5. Affected persons inherit 2 mutant genes, one from each parent. Cells carrying ERCC8 mutations are hypersensitive to UV light. They do not recover the ability to synthesize ribonucleic acid (RNA) after exposure to UV light. In addition, the cells cannot remove and degrade deoxyribonucleic acid (DNA) lesions from strands that have active transcription.

Mutations in the DNA excision repair gene ERCC6 located on band 10q11 cause CS type 2 (MIM number 133540; CSB). This gene encodes helicase, a protein that is presumed to have DNA unwinding function. Mutations include a deletion of exon 4, an amino acid substitution at the 106th glutamine to proline (Q106P) in the WD-40 repeat motif of the CSA protein, and large deletion in the upstream region, including exon 1 of the CSA gene. The Q106P mutation could alter the propeller structure of the CSA protein, which is important for the formation of the CSA protein complex. Additionally, a missense mutation (A205P) and a nonsense (E13X) mutation have been identified, as well as a new common single nucleotide polymorphism in CKN1. No genotype-phenotype correlation exists. _EMedicine

We can hope that experience in augmenting DNA repair in the tragic accelerated aging syndromes may be helpful in devising strategies to augment DNA repair in helping to delay normal aging.

Previously published in Al Fin Longevity

DNA Repair: BRIT1 in Cancer--Built-In Telomerase Inhibitor Blocks Cell Immortalisation

BRIT1 is a gene that functions as a transcriptional inhibitor of hTERT (human telomerase reverse transcriptase), the catalytic subunit of human telomerase. hTERT is the rate limiting determinant of telomerase and cell immortalisation.

This Newswise newsrelease discusses recent developments in uncovering the relationship between BRIT1, hTERT, DNA repair, and cancer onset.

A single gene plays a pivotal role launching two DNA damage detection and repair pathways in the human genome, suggesting that it functions as a previously unidentified tumor suppressor gene, researchers at The University of Texas M. D. Anderson Cancer Center report in Cancer Cell.

The advance online publication also reports that the gene - called BRIT1 - is under-expressed in human ovarian, breast and prostate cancer cell lines.

Defects in BRIT1 seem to be a key pathological alteration in cancer initiation and progression, the authors note, and further understanding of its function may contribute to novel, therapeutic approaches to cancer.

"Disruption of BRIT1 function abolishes DNA damage responses and leads to genomic instability," said senior author Shiaw-Yih Lin, Ph.D., assistant professor in the Department of Molecular Therapeutics at M. D. Anderson. Genomic instability fuels the initiation, growth and spread of cancer.

A signaling network of molecular checkpoint pathways protects the human genome by detecting DNA damage, initiating repair and halting division of the damaged cell so that it does not replicate.

In a series of laboratory experiments, Lin and colleagues show that BRIT1 activates two of these checkpoint pathways. The ATM pathway springs into action in response to damage caused by ionizing radiation. The ATR pathway responds to DNA damage caused by ultraviolet radiation.

By using small interfering RNA (siRNA) to silence the BRIT1 gene, the scientists shut down both checkpoint pathways in cells exposed to either type of radiation.

Researchers then used siRNA to silence the gene in normal human mammary epithelial cells (HMEC). The result: Inactivation of the gene caused chromosomal aberrations in 21.2 to 25.6 percent of cells. Control group HMEC had no cells with chromosomal aberrations. In cells with the gene silenced that were then exposed to ionizing radiation, 80 percent of cells had chromosomal aberrations.

"We also found that BRIT1 expression is aberrant in several forms of human cancer," Lin said. The team found reduced expression of the gene in 35 of 87 cases of advanced epithelial ovarian cancer. They also found reduced expression in breast and prostate cancer tissue compared with non-cancerous cells.

Genetic analysis of breast cancer specimens revealed a truncated, dysfunctional version of the BRIT1 protein in one sample.

Loss of the DNA damage checkpoint function and the ability to proliferate indefinitely are two cellular changes required for the development of cancer. Lin and colleagues have now tied the gene to both factors. They previously identified BRIT1 as a repressor of hTERT, a protein that when reactivated immortalizes cells, allowing them to multiply indefinitely.

Source.

The cell signaling pathways that regulate detection of DNA damage and the subsequent halting of the cell cycle, DNA repair, and possibly trigger apoptosis, is very complex. By using tools such as siRNA to selectively block individual components of this complex network, researchers can get closer to understanding how this intricate cell machinery functions.

The relationship between BRIT1, hTERT, cancer and cell immortalisation, suggests tantalising clues to possible cancer treatments as well as anti-aging therapies. But it is still too early to be certain of the best avenue of approach. This is an intriguing line of research, nevertheless.

Dead Before Fifty--Damage to DNA Mounts With Loss of Repair Protein

Our DNA is the basis for every moment of our existence. Our cells have complex mechanisms for repairing incidental day-to-day damage that inevitably occurs to DNA. But what happens when the DNA repair mechanism breaks down? That is what happens in Werner's Syndrome, when the gene for the WRN helicase protein is defective, and repairs normally initiated by WRN do not take place.

This newsreport describes the work of two California research teams who have solved the crystal structure of the WRN protein.

When the gene for WRN is defective the result is Werner's syndrome, a rare inherited disease that shows no symptoms until puberty but soon causes rapid aging. Beginning in their twenties, victims may become afflicted with cataracts, hair loss, wrinkled skin, osteoporosis, arteriosclerosis, and type II diabetes; many patients contract cancer, and most die by the age of 50. Understanding how the WRN protein normally works to maintain genomic integrity could lead to new forms of treatment for cancer and age-related pathologies.

"One reason we are particularly interested in WRN is because Werner's syndrome is unusual among premature-aging diseases, in that children are born normal and show no signs of disease until early adulthood," says Steven Yannone of Berkeley Lab's Life Sciences Division. "This gives us a better chance of clearly separating defects in development from aging."

"We wanted to study the protein itself because it is unique," says Jeff Perry of the Scripps Research Institute's Department of Molecular Biology and Skaggs Institute for Chemical Biology, formerly of Berkeley Lab, who led the research with Yannone. "WRN belongs to a family of enzymes called RecQ helicases" - of which there are five in the human genome, performing important functions in DNA replication, recombination, and repair - "but in this family, only WRN has coupled a helicase function and a nuclease function within the same protein."

Helicases open up the double helix of DNA, while nucleases degrade one or both of the DNA chains; both operations are critical to repairing errors and proofreading DNA sequences. One part of WRN is an exonuclease, which starts working from the end of a DNA strand. Perry and Yannone and their colleagues determined the structure of the WRN exonuclease domain (WRN-exo) and showed how the enzyme may function in a series of specific DNA repair events. Their findings will soon appear in Nature Structural & Molecular Biology and are now available online.

....Tainer says, "The exonuclease domain of the WRN protein is a prime example of what we in SBDR call 'master keys,' structures that open doors to lots of different repair pathways. Among other things, WRN is involved in repairing double-strand breaks, single-strand breaks, replication forks and junctions, even DNA-RNA duplexes. How does one protein know how to interact in so many different processes? If we can understand how this unique protein works, we'll have a key to how all these pathways work in human beings."

Cooper says, "Understanding the relationship between the structure of WRN and how it performs its multiple functions to prevent aging and cancer is a perfect example of the kind of problem we designed the SBDR program to solve. With 21 investigators in 15 institutions, SBDR's goal is to gain fundamental insights into the molecular machines that maintain genomic integrity, by applying a range of experimental techniques." There is much more information from the research at the source.

There are many potential causes for aging, and we may have to study them all in depth before a truly effective rejuvenation therapy scheme can be developed that is broadly applicable to most people. Learning how to help people who suffer from diseases such as WS are the top priority. The spinoffs from such new knowledge will benefit everyone.

This link will take you to a few tutorials on DNA repair proteins. WRN is one of many repair proteins that often work in concert to repair various types of damage to DNA. This article suggests some of the complexity involved.