A team led by Massachusetts General Hospital (MGH) researchers has identified a genetic signature that appears to reflect the risk of tumour recurrence or spread in men surgically treated for prostate cancer. If confirmed in future studies, this finding not only may help determine which patients require additional treatment after the cancerous gland has been removed, it also may help address the most challenging problem in prostate cancer treatment – distinguishing tumours that require aggressive treatment from those that can safely be monitored.
‘Radical prostatectomy is the standard of care for men whose cancer is advanced but confined to the prostate gland, but we know that the factors we use to determine which patients need radiation therapy after surgery are inadequate,’ says W. Scott McDougal, MD, of the MGH Department of Urology, corresponding author of the report. ‘The treatments available to our patients can have significant impact on their quality of life, so a better way to know which patients with localised cancer need additional therapy after surgery and which require no additional treatment is a significant unmet need.’
Gene expression signatures indicating patient prognosis and sometimes the most appropriate treatment have been incorporated into care for breast cancer and other tumours. Studies looking for such markers in prostate cancer have had variable results, and their potential usefulness to guide treatment has not been determined. For the current study the research team – led by Chin-Lee Wu, MD, PhD, of the MGH Department of Pathology – examined samples of malignant tissue from around 200 prostate cancer patients who had radical prostatectomies at the MGH between 1993 and 1995, analyzing the expression patterns of more than 1,500 genes associated with prostate cancer in earlier studies. With the results of that analysis, they developed a 32-gene index to reflect the likelihood that a patient’s tumour would recur, signified by detectable levels of prostate-specific antigen (PSA) after the gland had been remove, or spread.
To validate the usefulness of the index, they used it to analyse tissue samples from a different group of almost 300 patients who had their prostates removed in 1996 and 1997, comparing the index with currently used prognostic factors – such as PSA levels, physical examination, and a tumour’s microscopic appearance – to see how accurately each predicted the actual incidence of tumour recurrence or metastasis during the 10 years after surgery. The expression-based index proved to be the most accurate method. Among those it designated as high-risk, the actual incidence of tumor recurrence was 47 percent and of metastasis, 14 percent. Among those classified as intermediate risk, actual recurrence was 22 percent, and metastasis occurred in 2 percent. No recurrence or metastasis were seen in patients classified as low-risk by the gene-expression index.
To get a sense of whether the index could help determine risk at the time of diagnosis, the researchers used it to assess pre-surgical needle biopsy samples from 79 patients in the validation group. The risk assignment based on biopsy results closely matched the assessment based on surgically removed tissue, and the prognostic ability of the index was better than that of other pathological information available at the time a biopsy was taken. Because the current report is based on study of patients treated at a single institution, the authors note, it requires confirmation in larger, multi-institutional studies.
‘A more accurate prognosis at the time of diagnosis could give patients and their physicians much more confidence in choosing a definitive therapy or pursuing active surveillance for those at low risk, which could reduce over-treatment, a critical issue in disease management,’ says lead author Wu, an associate professor of Pathology at Harvard Medical School. McDougal is the the Kerr Professor of Urology, at HMS. Massachusetts General Hospital

The Journal of the American Heart Association published results from a study directed by Dr. Éric Thorin of the Montreal Heart Institute (MHI), which suggests for the first time that a blood protein contributes to the early development of atherosclerosis.
Dr. Thorin, his team and his collaborators discovered that the blood levels of angiopoietin-like protein 2 (angptl2) are six times higher in subjects with coronary heart disease than in healthy subjects of the same age. Their basic research study also revealed that angptl2, which is undetectable in young mice, increases with age in healthy subjects and increases prematurely in subjects who have high cholesterol and pre-atherosclerotic lesions. Entitled ‘Angiopoietin-like 2 promotes atherogenesis in mice,’ this study was conducted using an animal model consisting of three to twelve-month-old mice. These results represent a major advance in the prevention and treatment of atherosclerosis. ‘Although much work remains to be done to broaden our knowledge of this protein’s mechanisms of action, angiopoietin-like protein 2 may represent an early biomarker not only to prevent vascular damage but also to predict atherosclerotic disease,’ explained Dr. Thorin. For 15 years, Dr. Thorin, a researcher at the MHI Research Centre and full professor at Université de Montréal, has been interested in the evolution of artery function during the ageing process and in the underlying mechanisms of atherosclerosis.
More specifically over the past five years, he has looked at the role of this particular protein. Thanks to his work, we now know that angptl2 causes a high degree of vascular inflammation. Blood levels of this protein increase in patients with cardiovascular disease as well as in people with complications related to diabetes, obesity and cancer in which the small blood vessels are damaged, as all of these diseases are associated with chronic inflammation.
According to Dr. Anil Nigam, a cardiologist and specialist in cardiovascular disease prevention at the MHI and co-author of the study, ‘Prevention is the ideal solution to delay the onset of atherosclerosis, and an early blood marker such as angptl2—if future clinical studies confirm this finding—will serve as an important tool to identify at-risk subjects who do not present with any symptoms of atherosclerotic disease.’ Montreal Heart Institute

Diagnosed in toddlers, X-linked hypophosphatemia (XLH) is the most common form of heritable rickets, in which soft bones bend and deform, and tooth abscesses develop because infections penetrate soft teeth that are not properly calcified. Researchers at McGill University and the Federal University of Sao Paulo have identified that osteopontin, a major bone and tooth substrate protein, plays a role in XLH. Their discovery may pave the way to effectively treating this rare disease.
The findings were made by the laboratories of Marc McKee, a professor in the Faculty of Dentistry and the Department of Anatomy and Cell Biology at McGill University, and of Nilana M.T. Barros, a professor at the Federal University of Sao Paulo. The team built upon previous research that had shown that mutations in the single gene PHEX are responsible for causing XLH.
‘XLH is caused in part by renal phosphate wasting, which is the urinary loss from the body of phosphate, an important building block of bones and teeth, along with calcium.’ says Prof. McKee. ‘In pursuing other factors that might contribute to XLH, we used a variety of research methods to show that PHEX enzymatic activity leads to an essentially complete degradation of osteopontin in bones.’
This loss of osteopontin, a known potent inhibitor of mineralisation (or calcification) in the skeleton and dentition, normally allows bones and teeth to mineralise and thus harden to meet the biomechanical demands placed on them. In XLH patients lacking functional PHEX enzyme, osteopontin and some of its smaller potent inhibitory peptides are retained and accumulate within the bone. This prevents their hardening and leads to soft deformed bones such as bowed legs (or knock-knees) seen in toddlers.

While not life-threatening, this decreased mineralisation of the skeleton (osteomalacia), along with the soft teeth, soon leads to a waddling gait, short stature, bone and muscle pain, weakness and spontaneous tooth abscesses.

The fact that these symptoms are only partially improved by the standard treatment with phosphate – which improves circulating phosphate levels – prompted the researchers to look for local factors within the bone that might be blocking mineralisation in these patients.

‘With this new identification of osteopontin as a substrate protein for PHEX,’ says Professor Barros, ‘we can begin to develop an enzyme-replacement therapy to treat XLH patients who have non-functional PHEX, much as has been done using a different enzyme to treat another rare bone disease called hypophosphatasia.’ McGill University

Better diagnosis and treatment of cancer could hinge on the ability to better understand a single cell at its molecular level. New research offers a more comprehensive way of analysing one cell’s unique behaviour, using an array of colours to show patterns that could indicate why a cell will or won’t become cancerous.

A University of Washington team has developed a new method for colour-coding cells that allows them to illuminate 100 biomarkers, a ten-time increase from the current research standard, to help analyse individual cells from cultures or tissue biopsies.
‘Discovering this process is an unprecedented breakthrough for the field,’ said corresponding author Xiaohu Gao, a UW associate professor of bioengineering. ‘This technology opens up exciting opportunities for single-cell analysis and clinical diagnosis.’

The research builds on current methods that use a smaller array of colours to point out a cell’s biomarkers – characteristics that indicate a special, and potentially abnormal or diseased, cell. Ideally, scientists would be able to test for a large number of biomarkers, then rely on the patterns that emerge from those tests to understand a cell’s properties.

The UW research team has created a cycle process that allows scientists to test for up to 100 biomarkers in a single cell. Before, researchers could only test for 10 at a time.

The analysis uses quantum dots, which are fluorescent balls of semiconductor material. Quantum dots are the smaller version of the material found in many electronics, including smartphones and radios. These quantum dots are between 2 and 6 nanometers in diameter, and they vary on the colour they emit depending on their size.

Cyclical testing hasn’t been done before, though many quantum dot papers have tried to expand the number of biomarkers tested for in a single cell. This method essentially reuses the same tissue sample, testing for biomarkers in groups of 10 in each round.
‘Proteins are the building blocks for cell function and cell behaviour, but their makeup in a cell is highly complex,’ Gao said. ‘You need to look at a number of indicators (biomarkers) to know what’s going on.’

The new process works like this: Gao and his team purchase antibodies that are known to bind with the specific biomarkers they want to test for in a cell. They pair quantum dots with the antibodies in a fluid solution, injecting it onto a tissue sample. Then, they use a microscope to look for the presence of fluorescent colours in the cell. If they see particular quantum dot colours in the tissue sample, they know the corresponding biomarker is present in the cell.

After completing one cycle, Gao and co-author Pavel Zrazhevskiy, a UW postdoctoral associate in bioengineering, inject a low-pH fluid into the cell tissue that neutralises the colour fluorescence, essentially wiping the sample clean for the next round. Remarkably, the tissue sample doesn’t degrade at all even after 10 such cycles, Gao said.
For cancer research and treatment, in particular, it’s important to be able to look at a single cell at high resolution to examine its details. For example, if 99 percent of cancer cells in a person’s body respond to a treatment drug, but 1 percent doesn’t, it’s important to analyse and understand the molecular makeup of that 1 percent that responds differently.

‘When you treat with promising drugs, there are still a few cells that usually don’t respond to treatment,’ said Gao. ‘They look the same, but you don’t have a tool to look at their protein building blocks. This will really help us develop new drugs and treatment approaches.’ University of Washington

Our ability to analyse the genetic make-up of the human body has rapidly improved over the last few decades. The genetic basis of different diseases is gradually being deciphered through scientific research and more and more people are having genetic tests to diagnose or predict illness within the health care system.
Genetic tests developed over the past thirty years have focussed on identifying the cause for a range of different conditions. Targeted genetic testing looking at particular genes within the genetic code has thus been widely used. Techniques have now moved on so much, that it is often easier and cheaper to examine the entire genetic code, rather than home in on particular genes suggested by symptoms or a family history.
Genetic tests to date have therefore largely been done to answer particular questions; ‘Have I got a high chance of breast cancer?’ or ‘Have I inherited the condition in my family?’ Modern day genetic testing can also answer questions we haven’t posed, and which might reveal entirely unexpected risk of disease.
But what do our genes really say about us? And what if a genetic test showed something that wasn’t expected that could affect you in later life? And what is the effect on the individual’s family?
The University of Southampton is currently conducting a study, funded by Cancer Research UK and National Institute for Health Research, which is exploring the ethical issues in discovering unexpected genetic test results otherwise known as incidental findings (IFs). Through interviews with patients and health professionals the study is outlining how future clinical practice may have to change to incorporate the possibility discovering such incidental findings.
Professor Anneke Lucassen, a clinical geneticist at the University of Southampton and consultant in clinical genetics at Southampton General Hospital, comments: ‘Moving from targeted to broad genetic testing is resulting in a growing ethical and moral debate about how such tests should be used. There are questions we need to be thinking about as new technologies enter mainstream use.
‘Unlike an X-ray where you might unexpectedly find a tumour that needs management now, with genetic testing you might predict something that could happen in 10 or 20 years’ time. If you predict a genetic disease with any certainty, you are also potentially predicting something about their relatives who have not asked for the test. Should their relatives be told that they might also be at risk?
‘Medical technology is advancing at a rapid rate and could help a lot of people and their families, but the clinical guidelines and the advice for health professionals about communication and decision making needs to catch up.’
Anyone wanting to take part in the study should email cels@soton.ac.uk University of Southampton