A Potential Treatment For Ovarian Cancer – Claudin-3 Gene Silencing Using Small Interfering RNA

“… Ovarian tumors highly express two proteins, claudin-3 and -4. These proteins are associated with both an increase is cellular motility and survival of ovarian tumor cells.  Claudin-3 is also over expressed in breast and prostate tumors. This new therapy is targeting claudin-3 (CLDN3) using small interfering RNA (siRNA). More specifically, this team has developed a nanoparticulate, lipid-like delivery system for intraperitoneal delivery of siRNA to ovarian tumors. Tests of the therapeutic efficacy of CLDN3 siRNA in three different mouse models showed a significant reduction in tumor growth.  Additionally, these mice showed no ill side effects of the CLDN3 siRNA treatment. …”

“PAPER REVEALS POTENTIAL NEW TREATMENT FOR OVARIAN CANCER

Wynnewood, PA, February 9, 2009 – – – – – Ovarian cancer is the fourth most common cancer in women and has the highest mortality rate for gynecologic cancers because it is often diagnosed at an advanced stage. New effective therapies for the treatment of advanced stage ovarian cancer are urgently needed.

Today, a paper published in the Proceedings of the National Academy of Sciences (PNAS) by Dr. Janet Sawicki, Professor at the Lankenau Institute for Medical Research (LIMR), a team headed by Daniel G. Anderson, Ph.D. and Robert Langer, Sc.D. of the David H. Koch Institute for Integrative Cancer Research at the Massachusetts Institute of Technology (MIT) and David Bumcrot, Director of Research at Alnylam Pharmaceuticals, shows that a new therapy suppresses ovarian tumor growth and metastasis in preclinical studies.

Ovarian tumors highly express two proteins, claudin-3 and -4. These proteins are associated with both an increase is cellular motility and survival of ovarian tumor cells.  Claudin-3 is also over expressed in breast and prostate tumors. This new therapy is targeting claudin-3 (CLDN3) using small interfering RNA (siRNA). More specifically, this team has developed a nanoparticulate, lipid-like delivery system for intraperitoneal delivery of siRNA to ovarian tumors. Tests of the therapeutic efficacy of CLDN3 siRNA in three different mouse models showed a significant reduction in tumor growth.  Additionally, these mice showed no ill side effects of the CLDN3 siRNA treatment.

‘We are excited by the preclinical performance of these formulations, and are hopeful that the lipidoid-siRNA nanoparticulates developed here may enable new genetic therapies for ovarian cancer,’ said Anderson.

‘These findings offer new hope for a therapeutic treatment option for individuals with metastatic ovarian cancer and potentially other types of cancers that over-express CLDN3’, states Dr. Janet Sawicki.  ‘Our next step is to begin Phase I clinical trials to test for safety with hopes to bring this treatment to the patient in the next few years.’

This research was made possible through funding from the National Institutes of Health (NIH), the Sandy Rollman Ovarian Cancer Foundation of Havertown, PA, and Wawa.

Lankenau Institute for Medical Research
Founded in 1927, the Lankenau Institute for Medical Research (LIMR) is an independent, nonprofit biomedical research center located in suburban Philadelphia on the campus of the Lankenau Hospital. As part of the Main Line Health System, LIMR is one of the few freestanding, hospital-associated medical research centers in the nation.  The faculty and staff at the Institute are dedicated to advancing an understanding of the causes of cancer and heart disease. They use this information to help improve diagnosis and treatment of these diseases as well as find ways to prevent them. They are also committed to extending the boundaries of human health and well-being through technology transfer and education directed at the scientific, clinical, business and lay public communities. For more information visit: http://www.limr.org.

David H. Koch Institute for Integrative Cancer Research at MIT
Launched by MIT in 2008, the David H. Koch Institute for Integrative Cancer Research (KI) both transforms and transcends the Center for Cancer Research (CCR). CCR was founded in 1974 by Nobel Laureate and MIT Professor Salvador Luria, CCR has made enormous contributions to the field of cancer research. The Koch is one of only seven National Cancer Institute-designated basic research centers in the US and is comprised of faculty that have earned the most prestigious national and international science honors including the Nobel Prize and the National Medal of Science. For more information visit: web.mit.edu/ki/index.html.

Alnylam Pharmaceuticals, Inc.
Alnylam Pharmaceuticals, a leader in RNAi therapeutics, is a biopharmaceutical company developing novel therapeutics based on a breakthrough in biology known as RNA interference, or RNAi; a discovery that enables the creation of a broad new class of human therapeutics. Using RNAi, Alnylam has built a product engine to develop a deep pipeline of drug products to treat a wide array of important diseases. For more information visit: http://www.alnylam.com

Contact: Tava Shanchuk
Phone: (610) 645-3429
E-mail: shanchukt@mlhs.org”

RNA Interference Primer – Alnylam Pharmaceuticals

Quoted Source:  Paper Reveals Potential New Treatment for Ovarian Cancer, Press Release, Lankenau Institute for Medical Research, Feb. 9, 2009.

Primary Citation:  Claudin-3 gene silencing with siRNA suppresses ovarian tumor growth and metastasis; Huang YH, Bao Y, Peng W et. al., Proc Natl Acad Sci U S A. 2009 Feb 10. [Epub ahead of print]

Additional Resources:

• RNA Interference:  An Introduction to RNA Interference (RNAi) and Drug Development, Alnylam Pharmaceuticals (PDF Document).

• RNAi Explained Animation, Science Now, NOVA.

From Zero to Hero: HMGB1 Protein Found to Promote DNA Repair, Prevents Cancer

“An abundant chromosomal protein [HMGB1] that binds to damaged DNA prevents cancer development by enhancing DNA repair, researchers at The University of Texas M. D. Anderson Cancer Center report online this week in the Proceedings of the National Academies of Science.”

“An abundant chromosomal protein that binds to damaged DNA prevents cancer development by enhancing DNA repair, researchers at The University of Texas M. D. Anderson Cancer Center report online this week in the Proceedings of the National Academies of Science.

The protein, HMGB1 [High mobility group box 1] , was previously hypothesized to block DNA repair, said senior author Karen Vasquez, Ph.D., associate professor in M. D. Anderson’s Department of Carcinogenesis at the Science Park – Research Division in Smithville, Texas.

Identification and repair of DNA damage is the frontline defense against the birth and reproduction of mutant cells that cause cancer and other illnesses.

Pinpointing HMGB1’s role in repair raises a fundamental question about drugs under development to block the protein, Vasquez said. The protein also plays a role in inflammation, so it’s being targeted in drugs under development for rheumatoid arthritis and sepsis.

‘Arthritis therapy involves long-term treatment,’ Vasquez said. ‘Our findings suggest that depleting this protein may leave patients more vulnerable to developing cancer.’

Long known to attach to sites of damaged DNA, the protein was suspected of preventing repair. ‘That did not make sense to us, because HMGB1 is a chromosomal protein that’s so abundant that it would be hard to imagine cell repair happening at all if that were the case,’ Vasquez said.

In a series of experiments reported in the paper, Vasquez and first author Sabine Lange, a doctoral candidate in the Graduate School of Biomedical Sciences, tracked the protein’s impact on all three steps of DNA restoration: access to damage, repair and repackaging of the original structure, a combination of DNA and histone proteins called chromatin.

First, they knocked out the [HMGB1] gene in mouse embryonic cells [HMGB1 knockout cells] and then exposed cells to two types of DNA-damaging agents. One was UV light, the other a chemotherapy called psoralen that’s activated by exposure to darker, low frequency light known as UVA. In both cases, the cells survived at a steeply lower rate after DNA damage than did normal cells.

Next they exposed HMGB1 knockout cells and normal cells to psoralen and assessed the rate of genetic mutation. The knockout cells had a mutation frequency more than double that of normal cells, however, there was no effect on the types of mutation that occurred.

Knock out and normal cells were then exposed to UV light and suffered the same amount of damage. However, those with HMGB1 had two to three times the repair as those without. Evidence suggests that HMGB1 works by summoning other DNA repair factors to the damaged site, Vasquez said.

The last step in DNA repair is called chromatin remodeling. DNA does not exist in a linear structure in the chromosome, but wraps around specialized histone proteins. This chromatin structure permits access to DNA when it is loose, or opened up, and blocks access when it is more tightly wrapped. Presence of HMGB1 resulted in a much higher rate of chromatin assembly in both undamaged and UVC-damaged cells.

Lange and Vasquez hypothesize that HMGB1 normally binds to the entrance and exit of DNA nucleosomes, so is nearby when DNA damage occurs. It then binds to and bends the damaged site at a 90-degree angle, a distortion that may help DNA repair factors recognize and repair the damage. After repair it facilitates restructuring of the chromatin.

Co-author with Lange and Vasquez is David Mitchell, Ph.D., professor of carcinogenesis.

The research was supported by grants from the National Cancer Institute and the National Institute of Environmental Health Sciences as well as an American Legion Auxiliary fellowship. 07/21/08”

Quoted Source: Once Suspect Protein Found to Promote DNA Repair, Prevent Cancer – M. D. Anderson scientists caution against targeting HMGB1 to treat other disease, M. D. Anderson News Release, July 21, 2008.