Posts Tagged ‘nature’

Sabotage as therapy: Aiming lupus antibodies at vulnerable cancer cells

The findings were published recently in Nature‘s journal Scientific Reports.

The study, led by James E. Hansen, M.D., assistant professor of therapeutic radiology at Yale School of Medicine, found that cancer cells with deficient DNA repair mechanisms (or the inability to repair their own genetic damage) were significantly more vulnerable to attack by lupus antibodies.

“Patients with lupus make a wide range of autoantibodies that attack their own cells and contribute to the signs and symptoms associated with lupus. Some of these antibodies actually penetrate into cell nuclei and damage DNA, and we suspected that we may be able to harness the power of these antibodies for use in targeted cancer therapy,” Hansen said.

The genetic code that determines how a cell develops is written in DNA. Damage to this code can cause a cell to malfunction, die, or transform into a cancer cell. Normal cells are equipped to repair damaged DNA and preserve the genetic code, but many cancer cells have defective DNA repair machinery and accumulate genetic mutations.

This difference between normal cells and certain cancer cells creates an opportunity to develop therapies that damage DNA and only kill cancer cells that cannot repair the damage. However, DNA is sequestered inside cell nuclei, where delivery of therapies can be challenging. Yale Cancer Center researchers are finding that naturally occurring lupus antibodies just may be a solution to this problem.

“Lupus antibody-based cancer therapy is an emerging new concept, and I believe we are just seeing the tip of the iceberg in terms of the potential of this approach,” said Hansen.

The researchers previously found that a lupus antibody called 3E10 inhibits DNA repair and sensitizes cancer cells to DNA damage, and they have now found that the DNA-damaging lupus antibody 5C6 is toxic to DNA repair-deficient cancer cells.

“Now that we know that more than one lupus antibody has a selective effect on cancer cells, I am confident that additional lupus autoantibodies with even greater therapeutic potential await discovery,” Hansen said.

source : http://www.sciencedaily.com/releases/2014/09/140902151302.htm

Understanding, improving body’s fight against pathogens

While they exist in small populations in humans, the large amounts of antibodies secreted by plasma cells make them key to the body’s immune system and its ability to defend itself against pathogens, such as bacteria and viruses. Proper maintenance of a pool of plasma cells is also critical for the establishment of lifelong immunity elicited by vaccination.

Dysregulation of plasma cell production and maintenance could lead to autoimmune diseases and multiple myeloma. Autoimmune diseases occur when the immune system does not distinguish between healthy tissue and antigens, which are found in pathogens. This results in expansion of plasma cells which produce excessive amounts of antibodies leading to destruction of one’s own healthy tissue. The discoveries by scientists in BTI’s Immunology Group have improved understanding of the mechanism by which plasma cells are developed from a major class of white blood cells called B cells.

For the first time, the molecule DOK3 was found to play an important role in formation of plasma cells. While calcium signalling typically controls a wide range of cellular processes that allow cells to adapt to changing environments, it was found to inhibit the expression of the membrane proteins essential for plasma cell formation. These membrane proteins include PDL1 and PDL2, and represent some of the key targets for the development of immunotherapy by pharmaceutical companies. DOK3 was able to promote the production of plasma cells by reducing the effects of calcium signalling on these membrane proteins. The absence of DOK3 would thus result in defective plasma cell formation.

In another study, BTI scientists discovered the importance of SHP1 signalling to the long term survival of plasma cells. While the molecule SHP1 has a proven role in prevention of autoimmune diseases, it was found that the absence of SHP1 would result in the failure of plasma cells to migrate from the spleen where they are generated to the bone marrow, a survival niche where they are able to survive for much longer periods. This could result in a reduction of the body’s immune response and thus, an increased susceptibility to infections and diseases. The scientists in this study also successfully rectified the defective immune response caused by an absence of SHP1 by applying antibody injections, which might advance the development of therapeutics. On the other hand, targeting SHP1 might be a strategy to treat multiple myeloma where the accumulation of cancerous plasma cells in the bone marrow survival niches is undesirable.

Findings hold potential for improved treatment

The discovery of these new targets for modulating the antibody response allows the development of novel therapeutic strategies for patients with autoimmune diseases and cancer.Understanding the mechanism that governs plasma cell differentiation is also critical for the optimal design of vaccines and adjuvants, which are added to vaccines to boost the body’s immune response.

Prof Lam Kong Peng, Executive Director of BTI, said, “These findings allow better understanding of plasma cells and their role in the immune system. The identification of these targets not only paves the way for development of therapeutics for those with autoimmune diseases and multiple myeloma, but also impacts the development of immunological agents for combating infections.”

source : http://www.sciencedaily.com/releases/2014/09/140902115036.htm

Repurposing anti-depressant medication to target medulloblastoma

The multi-institutional group, led by scientists at Cancer and Blood Diseases Institute (CBDI) at Cincinnati Children’s Hospital Medical Center, publish their results in the journal’s online edition on Aug. 24. The researchers suggest their laboratory findings in mouse models of the disease could lead to a more targeted and effective molecular therapy that would also reduce the harmful side effects of current treatments, which include chemotherapy, radiation or surgery.

“Although current treatments improve survival rates, patients suffer severe side effects and relapse tumors carry mutations that resist treatment,” said lead investigator Q. Richard Lu, PhD, scientific director of the Brain Tumor Center, part of the CBDI at Cincinnati Children’s. “This underscores an urgent need for alternative targeted therapies, and we have identified a potent tumor suppressor that could help a subset of patients with an aggressive form of medulloblastoma.”

Using genetically-engineered mice to model human medulloblastoma, the authors identified a gene called GNAS that encodes a protein called Gsa. Gsa kicks off a signaling cascade that researchers found suppresses the initiation of an aggressive form of medulloblastoma driven by a protein called Sonic hedgehog — considered one of the most important molecules in tissue formation and development.

The scientists used an anti-depressant medication called Rolipram — approved for behavioral therapy for use in Europe and Japan — to treat mice that were engineered not to express the GNAS gene. Lack of GNAS allowed aggressive formation of medulloblastoma tumors in neural progenitor cells of the GNAS mutant mice.

Rolipram treatment in the mice elevated levels of a molecule called cAMP, which restored the GNAS-Gsa pathway’s tumor suppression function. This caused the tumors to shrink and subside. The study also suggests that elevating cAMP levels in cells enhances the potency of Sonic hedgehog inhibitors, currently being tested in clinical trials to fight tumor growth.

The scientists stressed that a significant amount of additional research is needed before their findings could become directly relevant to clinical treatment. The authors also caution that the effect of raising cAMP levels may depend on the type of cancer, and that laboratory results in mice do not always translate uniformly to humans.

source : http://www.sciencedaily.com/releases/2014/08/140824152337.htm