Massachusetts General Hospital (MGH) investigators have used a new sequencing method to identify a group of genes used by the brain’s immune cells – called microglia – to sense pathogenic organisms, toxins or damaged cells that require their response. Identifying these genes should lead to better understanding of the role of microglia both in normal brains and in neurodegenerative disorders and may lead to new ways to protect against the damage caused by conditions like Alzheimer’s and Parkinson’s diseases. The study also finds that the activity of microglia appears to become more protective with ageing, as opposed to increasingly toxic, which some previous studies had suggested.
‘We’ve been able to define, for the first time, a set of genes microglia use to sense their environment, which we are calling the microglial sensome,’ says Joseph El Khoury, MD, of the MGH Center for Immunology and Inflammatory Diseases and Division of Infectious Diseases, senior author of the study. ‘Identifying these genes will allow us to specifically target them in diseases of the central nervous system by developing ways to upregulate or downregulate their expression.’
A type of macrophage, microglia are known to constantly survey their environment in order to sense the presence of infection, inflammation, and injured or dying cells. Depending on the situation they encounter, microglia may react in a protective manner – engulfing pathogenic organisms, toxins or damaged cells – or release toxic substances that directly destroy microbes or infected brain cells. Since this neurotoxic response can also damage healthy cells, keeping it under control is essential, and excess neurotoxicity is known to contribute to the damage caused by several neurodegenerative disorders.
El Khoury’s team set out to define the transcriptome – the complete set of RNA molecules transcribed by a cell – of the microglia of healthy, adult mice and compared that expression profile to those of macrophages from peripheral tissues of the same animals and of whole brain tissue. Using a technique called direct RNA sequencing, which is more accurate than previous methods, they identified a set of genes uniquely expressed in the microglia and measured their expression levels, the first time such a gene expression ‘snapshot’ has been produced for any mammalian brain cell, the authors note.
Since ageing is known to alter gene expression throughout the brain, the researchers then compared the sensome of young adult mice to that of aged mice. They found that – contrary to what previous studies had suggested – the expression of genes involved in potentially neurotoxic actions, such as destroying neurons, was down-regulated as animals aged, while the expression of neuroprotective genes involved in sensing and removing pathogens was increased. El Khoury notes that the earlier studies suggesting increased neurotoxicity with ageing did not look at the cells’ full expression profile and often were done in cultured cells, not in living animals.
‘Establishing the sensome of microglia allows us to clearly understand how they interact with and respond to their environment under normal conditions,’ he explains. ‘The next step is to see what happens under pathologic conditions. We know that microglia become more neurotoxic as Alzheimer’s disease and other neurodegenerative disorders progress, and recent studies have identified two of the microglial sensome genes as contributing to Alzheimer’s risk. Our next steps should be defining the sensome of microglia and other brain cells in humans, identifying how the sensome changes in central nervous system disorders, and eventually finding ways to safely manipulate the sensome pharmacologically.’ Massachusetts General Hospital

The once sketchy landscape of the molecular defects behind bladder cancer now resembles a road map to new, targeted treatments thanks to the unified efforts of scientists and physicians at 40 institutions.
Deep molecular analysis of 131 muscle-invasive bladder cancer tumours found recurring defects in 32 genes for the cancer that currently has no targeted therapies.
‘By dramatically increasing our knowledge of the molecular basis of bladder cancers, this project casts a spotlight on particular molecules and biological pathways that may serve as targets for a more individualised approach to therapy,’ said project co-chair, lead and senior author John Weinstein, M.D., Ph.D., professor and chair of the Department of Bioinformatics and Computational Biology at The University of Texas M.D. Anderson Cancer Center in Houston.
‘While many of these genomic alterations have been tied to other cancers, nine of these genes have never been reported as significantly mutated in any other type of malignancy,’ Weinstein said. ‘These findings mark additional progress away from defining cancer by organ site and toward molecular classification that spans tumour types.’
Basis for investigating novel therapies and new uses of existing drugs
The most common bladder cancer, urothelial carcinoma, will kill an estimated 15,000 Americans in 2014, with 10 times as many deaths worldwide. Muscle-invasive disease is the most lethal form. Current treatment includes surgery, cisplatin-based multi-agent chemotherapy and radiation.
‘These TCGA data provide a perfect storm for advancing treatment for muscle invasive and hard-to-treat cancer,’ said project co-leader and co-senior author Seth P. Lerner, M.D., professor and chair of Urologic Oncology and Bladder Cancer program leader at Baylor College of Medicine in Houston.
‘We found potential therapeutic targets in 69 percent of tumours and identified bladder cancer subtypes based on gene mutation and expression data,’ Lerner said. ‘One subtype looks similar to squamous cell cancer of the head, neck and lung and basal-like breast cancer. Another subtype looks similar to luminal A breast cancer. These genomic similarities create a logical path to test targeted therapies from these other subtypes of cancer rather than treating bladder cancers as one disease.’
Lerner said long-term planning for clinical trials based on the TCGA data has begun in earnest and will continue this week during the 2014 Genitourinary Cancers Symposium in San Francisco.
Researchers analysed tumours for genetic mutations, gene copy number (deletions and amplifications), gene expression of messenger RNA, microRNA and protein expression, among other factors.
Two biological pathways provided the most common therapeutic targets, including molecules addressed by drugs in clinical trials or approved for other types of cancer.
45 percent of tumours had targets in the growth-factor-signalling receptor tyrosine kinase/MAPK pathway, including HER2 – best known as a drug target in about one third of breast cancers – in 15 percent of tumours, EGFR in 9 percent and FGFR3 in 17 percent.
42 percent had targets in the PI3K/AKT/mTOR pathway, including PIK3CA, which occurred in 17 percent of tumours, TSC1 or TSC2 in 9 percent and AKT3 in 10 percent of tumours. PI3K inhibitors are under development and mTOR inhibitors have been approved for select cancers.
A striking new finding, Weinstein said, was of frequent alterations in genes involved with the regulation of chromatin, the combination of DNA and histone proteins that makes up chromosomes.
Chromatin remodelling greatly influences gene expression and the team found alterations in this pathway in 89 percent of tumours, more than in any other type of cancer analysed to date. This makes bladder cancer a prime candidate for a new class of drugs under development, the authors noted.
Viral DNA was found in 6 percent of tumours, suggesting that viral infection might play a role in the development of a small percentage of bladder cancers. M D Anderson Cancer Center

How to diagnose and manage Heparin-Induced Thrombocytopenia (HIT)?
by Pr Yves Gruel – Professor of Hematology, Trousseau Hospital and University Francois Rabelais, Tours (France)

Type II Heparin-Induced Thrombocytopenia (HIT) is an immune-mediated adverse effect of heparin treatment. Although rare, this complication can be serious and possibly life threatening.

Approximately one third of hospitalized patients are exposed to heparins. It is therefore of great importance to know how to:

• diagnose HIT in order to identify the patients who will benefit from an alternative anticoagulant treatment

• avoid HIT overdiagnosis to minimize the risks of bleedings and the costs associated with the use of alternative anticoagulants

This webinar will focus on HIT pathophysiology, and will outline the necessity of an accurate diagnosis and how it can be achieved. Alternative anticoagulant treatment options will also be discussed.

This 30-minute presentation will be followed by a 15-minute live chat with the speaker.

Pr Gruel is the Head of the Hematology Department at Trousseau University Hospital in Tours and is also leading the Hemophilia Care Center.
Apart from his clinical activity focusing on bleeding and thrombotic disorders, his main research topics are today heparin-induced thrombocytopenia (HIT) and the role of specific coagulation proteins in cancer.

He is currently the President of GEHT (French study Group on Haemostasis and Thrombosis), and Chairman of the ISTH Scientific and Standardization Committee on Platelet Immunology.

Save the date! Friday January 31st 2014 at 4:00 p.m. CET (Central European Time)

To attend this webinar, please register at www.stagowebinars.com.

Changes to two previously unstudied genes are the centrepiece of a new theory regarding the cause and development of endometriosis, a chronic and painful disease affecting 1 in 10 women.

The discovery by Northwestern Medicine scientists suggests epigenetic modification, a process that enhances or disrupts how DNA is read, is an integral component of the disease and its progression. Matthew Dyson, PhD, research assistant professor of Obstetrics and Gynecology-Reproductive Biology Research and Serdar Bulun, MD, chair of Obstetrics and Gynecology also identified a novel role for a family of key gene regulators in the uterus.

‘Until now, the scientific community was looking for a genetic mutation to explain endometriosis,’ said Dr. Bulun, a member of the Center for Genetic Medicine and the Robert H. Lurie Comprehensive Cancer Center. ‘This is the first conclusive demonstration that the disease develops as a result of alterations in the epigenetic landscape and not from classical genetic mutations.’

Women develop endometriosis when cells from the lining of the uterus, usually shed during menstruation, grow in other areas of the body. The persistent survival of these cells results in chronic pelvic pain and infertility. Although the cause of the disease has remained unknown on a cellular level, there have been several different models established to explain its development.

Endometriosis only occurs in menstruating primates, suggesting that the unique evolution behind uterine development and menstruation are linked to the disease. Scientists consider retrograde menstruation – cells moving up the fallopian tubes and into the pelvis – as one probable cause.
Previous models, however, have been unable to explain why only 10 percent of women develop the disease when most experience retrograde menstruation at some point. Nor do they explain instances of endometriosis that arise independent of menstruation.

Bulun and Dyson propose that an epigenetic switch permits the expression of the transcription factor GATA6 rather than GATA2, resulting in progesterone resistance and disease development.

‘We believe an overwhelming number of these altered cells reach the lining of the abdominal cavity, survive and grow,’ said Dr. Bulun, obstetrician-gynaecologist-in-chief at Northwestern Memorial’s Prentice Women’s Hospital. ‘These findings could someday lead to the first non-invasive test for endometriosis.’

Clinicians could then prevent the disease by placing teenagers predisposed to this epigenetic change on a birth control pill regimen, preventing the possibility of retrograde menstruation in the first place.

Dyson will also look to use the epigenetic fingerprint resulting from the presence of GATA6 rather than GATA2 as a potential diagnostic tool, since these epigenetic differences are readily detectable.

‘These findings have the potential to shift how we view and treat the disease moving forward,’ Dr. Bulun said. Feinberg School of Medicine

UCSF scientists say new finding could lead to more accurate prognosis
The stiffening of breast tissue in breast-cancer development points to a new way to distinguish a type of breast cancer with a poor prognosis from a related, but often less deadly type, UC San Francisco researchers have found in a new study.
The findings may lead eventually to new treatment focused not only on molecular targets within cancerous cells, but also on mechanical properties of surrounding tissue, the researchers said.
In a mouse model of breast cancer, scientists led by Valerie Weaver, PhD, professor of surgery and anatomy and director of the Center for Bioengineering and Tissue Regeneration at UCSF, identified a biochemical chain of events leading to tumour progression. Significantly, this chain of events was triggered by stiffening of scaffolding tissue in the microscopic environment surrounding pre-cancerous cells. The stiffening led to the production of a molecule that can be measured in human breast cancer tissue, and which the researchers found was associated with worse clinical outcomes.
‘This discovery of the molecular chain of events between tissue stiffening and spreading cancer may lead to new and more effective treatment strategies that target structural changes in breast cancers and other tumours,’ Weaver said.
In the mouse experiments, Janna Mouw, PhD, a UCSF associate specialist who works in Weaver’s lab, found that tissue stiffening in microscopic scaffolding known as the extracellular matrix, or ECM, increases signalling by ECM-associated molecules, called integrins. The integrins in turn trigger a signalling cascade within cells that leads to the production of a tumour-promoting molecule called miR-18a.
Unlike most cellular signalling molecules thus far studied by scientists, miR-18a is not a protein or a hormone, but rather a microRNA, another type of molecule recognised in recent years to play an important role in the lives of cells. The miR-18a dials down the levels of a protective, tumour-suppressing protein called PTEN, which often is disabled in cancerous cells, leading to abnormal biochemical signalling that can promote cancer growth. University of California – San Francisco