Friday, September 29, 2017

Synthetic molecule 'kicks and kills' some persistent HIV in mice

Scientists have designed a synthetic molecule that can reactivate dormant human immunodeficiency virus (HIV) in mice and lead to the death of some of the infected cells, according to a study published in PLOS Pathogens.

The new findings address a long-standing challenge in HIV treatment: While antiretroviral therapy can successfully stave off disease progression, the virus can silently persist in some cells for many years, so an infected person must be vigilantly treated for the rest of their life.
Previous studies have explored potential ways to eliminate latently infected cells, such as by stimulating them to produce some viral particles ("kick"), followed by cell death via the immune system or the virus itself ("kill"). A molecule called bryostatin 1 holds the potential to trigger a "kick and kill" response, but it is costly to obtain from its source, a marine animal known as Bugula neritina.
To address this challenge, Matthew Marsden and Jerome Zack of UCLA and Wender Group colleagues at Stanford have designed synthetic molecules capable of imitating the activity of bryostatin 1 and perhaps even improving on its function. In the new study, the team tested SUW133, one of their more promising synthetic bryostatin 1 analogs.
The researchers first demonstrated that SUW133, like bryostatin 1, is capable of activating latent HIV infection in cells removed from infected patients. Then, they tested SUW133 in mice of a strain commonly used for HIV research, in which the mouse immune system is modified to be similar to that of humans.
Molecular analysis revealed that SUW133 stimulated HIV protein production in latently infected cells in the mice. Within 24 hours, up to 25% of these cells then died. SUW133 was also better tolerated by the mice than was bryostatin 1.
These results support the potential for SUW133 to be used in a "kick and kill" treatment for HIV. Further research is needed to explore this potential and answer questions such as whether a greater percentage of cells could be killed over longer periods of time or with repeated dosing, whether similar effects might be seen in humans, and what the long-term effects of SUW133 may be.

Journal Reference:
  1. Matthew D. Marsden, Brian A. Loy, Xiaomeng Wu, Christina M. Ramirez, Adam J. Schrier, Danielle Murray, Akira Shimizu, Steven M. Ryckbosch, Katherine E. Near, Tae-Wook Chun, Paul A. Wender, Jerome A. Zack. In vivo activation of latent HIV with a synthetic bryostatin analog effects both latent cell "kick" and "kill" in strategy for virus eradication. PLOS Pathogens, 2017; 13 (9): e1006575 DOI: 10.1371/journal.ppat.1006575 
Courtesy: ScienceDaily


Wednesday, September 27, 2017

Alternative splicing, an important mechanism for cancer

Cancer, which is one of the leading causes of death worldwide, arises from the disruption of essential mechanisms of the normal cell life cycle, such as replication control, DNA repair and cell death. Thanks to the advances in genome sequencing techniques, biomedical researchers have been able to identify many of the genetic alterations that occur in patients that are common among and between tumor types. But until recently, only mutations in DNA were thought to cause cancer. In a new study published in the journal Cell Reports, researchers show that alterations in a process known as alternative splicing may also trigger the disease.

Although DNA is the instruction manual for cell growth, maturation, division, and even death, it's proteins that actually carry out the work. The production of proteins is a highly regulated and complex mechanism: cellular machinery reads the DNA fragment that makes up a gene, transcribes it into RNA and, from the RNA, makes proteins. However, each gene can lead to several RNA molecules through alternative splicing, an essential mechanism for multiple biological processes that can be altered in disease conditions.
Using data for more than 4,000 cancer patients from The Cancer Genome Atlas (TCGA project), a team led by Eduardo Eyras, ICREA research professor at the Department for Experimental and Health Sciences of the Pompeu Fabra University (DCEXS-UPF), has analyzed the changes in alternative splicing that occur in each tumor patient and studied how these changes could impact the function of genes. The results of the study show that alternative splicing changes lead to a general loss of functional protein domains, and particularly those domains related to functions that are also affected by genetic mutations in cancer patients.
"Thanks to our previous research, we know that tumor type and stage can be predicted by observing alterations in alternative splicing," says Eyras, head of the research group in Computational RNA Biology from the Research Programme on Biomedical Informatics (GRIB), a joint research unit of the Hospital del Mar Medical Research Institute (IMIM) and the DCEXS-UPF. "With this new study, we have discovered that changes in alternative splicing that occur in cancer impact protein functions in a way that is similar to that previously described for genetic mutations," he adds.
All of these alterations in protein functions would cause changes in cells morphology and function, giving them the characteristics of tumor cells, such as a high proliferative potential or the ability to avoid programmed cell death.
According to Adam Godzik, professor at Sanford Burnham Prebys Medical Discovery Institute (SBP) and co-author of the study, "These changes potentially have oncogenic power in cells, which means, the ability to turn a healthy cell into a cancer cell." A novel aspect of the study is that these changes tend to occur in genes other than those often mutated in cancer, and in patients with a low number of mutated genes.
"Changes in alternative splicing provide cancer with new ways in which it can escape fine cellular regulation. Therefore, the study of alternative splicing opens new doors in the research to cure cancer and may provide new alternatives to the treatment of this disease."
 
Journal Reference:
  1. Héctor Climente-González, Eduard Porta-Pardo, Adam Godzik, Eduardo Eyras. The Functional Impact of Alternative Splicing in Cancer. Cell Reports, 2017; 20 (9): 2215 DOI: 10.1016/j.celrep.2017.08.012 
Courtesy: ScienceDaily