July 15, 2011

New Gene Discovery May Treat Lymphoma In People and Pets

(Ivanhoe Newswire) "“ According to the Leukemia and Lymphoma Society, over 21,000 Americans died from lymphoma cancer last year. Lymphoma refers to a group of blood cancers that start in the lymphatic system, a network of lymph vessels and lymph nodes that play a vital role in the body's immune system. Researchers believe that a newly identified protein may be a potential target for diagnosing and treating lymphoma in humans and animals. The protein appears to play a key role in the formation of lymphoma and other tumors by inhibiting a tumor-suppressing gene.

"Results from this study suggest that a gene known as RNPC1 may play a key role in the development of lymphoma," Xinbin Chen, a veterinary oncologist from the University of California Davis School of Veterinary Medicine and UC Davis School of Medicine, and lead study author, was quoted saying.

Lymphoma occurs when a type of white cell, known as a lymphocyte, undergoes a malignant change and begins to multiply out of control. As the lymphocytes multiply rapidly, they eventually crowd out normal, healthy cells. In time, the cancerous lymphocytes accumulate in the lymph nodes, liver, spleen and other locations in the body. Lymphoma occurs spontaneously in dogs, representing 6 percent of all canine cancers, and is remarkably similar to lymphoma in humans.

One important gene, known as p53, plays an important role in suppressing cancer. This tumor suppressor gene checks cells' DNA for mutations that might cause cancer and then stops cell growth until the mutations can be repaired. If the mutations can't be repaired, P53 triggers cell death to prevent cancer from developing. If something goes wrong, p53 can mutate and produce undesirable proteins. Mutated proteins produced by p53 are present in 60 percent of all cancerous human tumors. Ultimately, when p53 and the process it controls are damaged, cancer often occurs.
Researchers have been extremely interested in how the activity of the p53 gene is regulated, since defects in this gene are so common in human and animal cancers. This led researchers to examine the RNPC1 gene, known to be an RNA-binding protein, regulating how other genes produce proteins. It was suspected that RNPC1 might play a role in causing lymphomas by inactivating the p53 gene.

By examining several types of human cancer cells and cells isolated from a mouse embryo, the team showed that the RNPC1 gene inhibited the activity of the p53 gene and reduced levels of the p53 protein in these cells. Finding the p53 protein levels increased when RNPC1 was out of the picture. Because the RNPC1 gene is located at a chromosome that is frequently found in human cancers, including lymphomas, the team examined the expression of RNPC1 in spontaneously occurring dog lymphomas and in non-cancerous canine lymph node tissue.

The results from the dog lymphoma tests showed that the RNPC1 gene is frequently overactive in dog lymphomas and as suspected, may play a role in the formation of lymphomas by inactivating the p53 gene. "Our findings are consistent with data from other cancer studies, which showed that RNPC1 is highly expressed in human cancers. This suggests that further studies are needed to analyze the expression of patterns of both RNPC1 and p53 in human tumor tissues," Dr. Chen said.

SOURCE: Genes & Development, July 14, 2011.