Understanding eye diseases is tricky enough. Knowing what causes them at the molecular level is even more confounding.

Now, University of Iowa researchers have created the most detailed map to date of a region of the human eye long associated with blinding diseases, such as age-related macular degeneration. The high-resolution molecular map catalogues thousands of proteins in the choroid, which supplies blood and oxygen to the outer retina, itself critical in vision. By seeing differences in the abundance of proteins in different areas of the choroid, the researchers can begin to figure out which proteins may be the critical actors in vision loss and eye disease.

“This molecular map now gives us clues why certain areas of the choroid are more sensitive to certain diseases, as well as where to target therapies and why,” says Vinit Mahajan, assistant professor in ophthalmology at the UI and corresponding author on the paper. “Before this, we just didn’t know what was where.”

What vision specialists know is many eye diseases, including age-related macular degeneration (AMD), are caused by inflammation that damages the choroid and the accompanying cellular network known as the retinal pigment epithelium (RPE). Yet they’ve been vexed by the anatomy: Why does it seem that some areas of the choroid-RPE are more susceptible to disease than others, and what is happening at the molecular level? The researchers set about to answer that question with non-diseased eye tissue donated by three deceased older individuals through the Iowa Lions Eye Bank. From there, Mahajan and Jessica Skeie, a post-doctoral researcher in ophthalmology at the UI, created a map that catalogues more than 4,000 unique proteins in each of the three areas of the choroid-RPE: the fovea, macula, and the periphery.

Why that’s important is now the researchers can see which proteins are more abundant in certain areas, and why. One such example is a protein known as CFH, which helps prevent a molecular cascade that can lead to AMD, much like a levee can keep flooding waters at bay. The UI researchers learned, though the map, that CFH is most abundant in the fovea. That helps, because now they know to monitor CFH abundance there; fewer numbers of the protein could mean increased risk for AMD, for instance.

“Now you can see all those differences that you couldn’t see before,” explains Mahajan, whose primary appointment is in the Carver College of Medicine. University of Iowa

Reduced levels of an anti-cancer protein make male brain cells more vulnerable to becoming tumors, according to a new study at Washington University School of Medicine in St. Louis.

New research at Washington University School of Medicine in St. Louis helps explain why brain tumours occur more often in males and frequently are more harmful than similar tumours in females. For example, glioblastomas, the most common malignant brain tumours, are diagnosed twice as often in males, who suffer greater cognitive impairments than females and do not survive as long.

The researchers found that retinoblastoma protein (RB), a protein known to reduce cancer risk, is significantly less active in male brain cells than in female brain cells.

“This is the first time anyone ever has identified a sex-linked difference that affects tumour risk and is intrinsic to cells, and that’s very exciting,” said senior author Joshua Rubin, MD, PhD. “These results suggest we need to go back and look at multiple pathways linked to cancer, checking for sex differences. Sex-based distinctions at the level of the cell may not only influence cancer risk but also the effectiveness of treatments.”

Rubin noted that RB is the target of drugs now being evaluated in clinical trials. Trial organizers hope the drugs trigger the protein’s anti-tumour effects and help cancer patients survive longer.

“In clinical trials, we typically examine data from male and female patients together, and that could be masking positive or negative responses that are limited to one sex,” said Rubin, who is an associate professor of pediatrics, neurology and anatomy and neurobiology. “At the very least, we should think about analysing data for males and females separately in clinical trials.”

Scientists have identified many sex-linked diseases that either occur at different rates in males and females or cause different symptoms based on sex. These distinctions often are linked to sex hormones, which create and maintain many but not all of the biological differences between the sexes.

However, Rubin and his colleagues knew that sex hormones could not account for the differences in brain tumour risk.

“Male brain tumor risk remains higher throughout life despite major age-linked shifts in sex hormone production in males and females,” he said. “If the sex hormones were causing this effect, we’d see major changes in the relative rates of brain tumours in males and females at puberty. But they don’t happen then or later in life when menopause changes female sex hormone production.”

Rubin used a cell model of glioblastoma to prove it is easier to make male brain cells become tumors. After a series of genetic alterations and exposure to a growth factor, male brain cells became cancerous faster and more often than female brain cells. Washington University School of Medicine

A new study suggests uric acid may play a role in causing metabolic syndrome, a cluster of risk factors that increases the risk of heart disease and type 2 diabetes.

Uric acid is a normal waste product removed from the body by the kidneys and intestines and released in urine and stool. Elevated levels of uric acid are known to cause gout, an accumulation of the acid in the joints. High levels also are associated with the markers of metabolic syndrome, which is characterized by obesity, high blood pressure, elevated blood sugar and high cholesterol. But it has been unclear whether uric acid itself is causing damage or is simply a by-product of other processes that lead to dysfunctional metabolism.

New research at Washington University School of Medicine in St. Louis suggests excess uric acid in the blood is no innocent bystander. Rather, it appears to be a culprit in disrupting normal metabolism.

“Uric acid may play a direct, causative role in the development of metabolic syndrome,” said first author Brian J. DeBosch, MD, PhD, an instructor in paediatrics. “Our work showed that the gut is an important clearance mechanism for uric acid, opening the door to new potential therapies for preventing or treating type 2 diabetes and metabolic syndrome.”

Recent research by the paper’s senior author, Kelle H. Moley, MD, the James P. Crane Professor of Obstetrics and Gynecology, and her collaborators has shown that a protein called GLUT9 is an important transporter of uric acid.

DeBosch, a paediatric gastroenterologist who treats patients at St. Louis Children’s Hospital, studied mice to learn what happens when GLUT9 stops working in the gut, essentially blocking the body’s ability to remove uric acid from the intestine. In this study, the kidney’s ability to remove uric acid remained normal.

Eating regular chow, mice missing GLUT9 only in the gut quickly developed elevated uric acid in the blood and urine compared with control mice. And at only 6-8 weeks of age, they developed hallmarks of metabolic syndrome: high blood pressure, elevated cholesterol, high blood insulin and fatty liver deposits, among other symptoms.

The researchers also found that the drug allopurinol, which reduces uric acid production in the body and has long been used to treat gout, improved some, but not all, of the measures of metabolic health. Treatment with the drug lowered blood pressure and total cholesterol levels.

Exposure to uric acid is impossible to avoid because it is a normal by-product of cell turnover in the body. But there is evidence that diet may contribute to uric acid levels. Many foods contain compounds called purines that break down into uric acid. And adding to growing concerns about fructose in the diet, evidence suggests that fructose metabolism in the liver also drives uric acid production.

“Switching so heavily to fructose in foods over the past 30 years has been devastating,” Moley said. “There’s a growing feeling that uric acid is a cause, not a consequence, of metabolic syndrome. And now we know fructose directly makes uric acid in the liver. With that in mind, we are doing further research to study what happens to these mice on a high-fructose diet.” University of Washington at St. Louis

Scientists at A*STAR’s Institute of Medical Biology (IMB) and the Bioinformatics Institute (BII) have found new clues to early detection and personalised treatment of ovarian cancer, currently one of the most difficult cancers to diagnose early due to the lack of symptoms that are unique to the illness.

There are three predominant cancers that affect women – breast, ovarian and womb cancer. Of the three, ovarian cancer is of the greatest concern as it is usually diagnosed only at an advanced stage due to the absence of clear early warning symptoms. Successful treatment is difficult at this late stage, resulting in high mortality rates. Ovarian cancer has increased in prevalence in Singapore as well as other developed countries recently. It is now the fifth most common cancer in Singapore amongst women, with about 280 cases diagnosed annually and 90 deaths per year.

IMB scientists have successfully identified a biomarker of ovarian stem cells, which may allow for earlier detection of ovarian cancer and thus allow treatment at an early stage of the illness.

The team has identified a molecule, known as Lgr5, on a subset of cells in the ovarian surface epithelium. Lgr5 has been previously used to identify stem cells in other tissues including the intestine and stomach, but this is the first time that scientists have successfully located this important biomarker in the ovary. In doing so, they have unearthed a new population of epithelial stem cells in the ovary which produce Lgr5 and control the development of the ovary. Using Lgr5 as a biomarker of ovarian stem cells, ovarian cancer can potentially be detected earlier, allowing for more effective treatment at an early stage of the illness (see Annex A).

Of the different types of ovarian cancers detected, high-grade serous ovarian carcinoma (HG-SOC) is the most prevalent of epithelial ovarian cancers. It has also proven to be one of the most lethal ovarian cancers, with only 30 per cent of such patients surviving more than five years after diagnosis. HG-SOC remains poorly understood, with a lack of biomarkers identified for clinical use, from diagnosis to prognosis of patient survival rates.

By applying bioinformatics analysis on big cancer genomics data, BII scientists were able to identify genes whose mutation status could be used for prognosis and development of personalized treatment for HG-SOC.

The gene, Checkpoint Kinase 2 (CHEK2), has been identified as an effective prognostic marker of patient survival. HG-SOC patients with mutations in this gene succumbed to the disease within five years of diagnosis, possibly because CHEK2 mutations were associated with poor response to existing cancer therapies.

Mortality after diagnosis currently remains high, as patients receive similar treatment options of chemotherapy and radiotherapy despite the diverse nature of tumour cells within tumours and across different tumour samples. With these findings, personalised medicine for ovarian cancer could be developed, with targeted treatment that would be optimised for subgroups of patients. A*Star

Stomach cancers fall into four distinct molecular subtypes researchers with The Cancer Genome Atlas (TCGA) Network have found. In the study, the scientists report that this discovery could change how researchers think about developing treatments for stomach cancer, also called gastric cancers or gastric adenocarcinomas.

Instead of considering gastric cancer as a single disease, as has been done in the past, researchers will now be able to explore therapies in defined sets of patients whose tumours have specific genomic abnormalities. Stomach cancers are a leading cause of cancer-related mortality worldwide, resulting in an estimated 723,000 deaths annually.

Previous attempts to examine the clinical characteristics of gastric cancer were hindered by how differently cancer cells can look under a microscope, even when from the same tumour. The researchers hope that the new classification system will serve as a valuable adjunct to the current pathology classification system, which has two categories: diffuse and intestinal.

“A key advance with this project is that we have identified and developed a much more useful classification system to find groups of gastric cancer that have distinct molecular features, and at the same time, we also identified key targets to pursue in different groups of patients,” said Adam Bass, M.D., Harvard Medical School, Dana-Farber Cancer Institute, the Broad Institute, Boston, and one of the lead investigators on the project. “This will provide a strong foundation for categorizing the disease and for doing so in a way in which we can develop clinical trials based on some of the critical molecular alterations that are driving different classes of cancers.”

The researchers identified the new subgroups through complex statistical analyses of molecular data from 295 tumours. They used six molecular analysis platforms including DNA sequencing, RNA sequencing, and protein arrays.

Tumours in the first group, which represented 9 percent of the tumours, were positive for Epstein-Barr virus (EBV) and had several other molecular commonalities. Tumours in a second subgroup (22 percent of the tumours) had high microsatellite instability (MSI), which is the tendency for mutations to accumulate in repeated sequences of DNA. The remaining subgroups differed in the level of somatic copy number alterations (SCNAs), which can result from duplication or deletion of sections of the genome. The tumours in the third subgroup, which comprised 20 percent of the tumours, were considered to have a low level of SCNAs and were called genomically stable. The remaining 50 percent of tumours were classified as chromosomally unstable, with a high level of SCNAs.

The EBV-positive subgroup of tumours was of particular interest. EBV is best known in the United States as the cause of infectious mononucleosis, which is characterized by fever, sore throat, and swollen lymph glands, especially in the neck. EBV is also suspected of causing certain cancers, including nasopharyngeal carcinoma and some types of lymphoma. Previous research had shown that EBV can be detected in a minority of gastric adenocarcinomas and that EBV genes are expressed in those tumours. However, this study found that the presence of EBV in gastric tumours is associated with a number of other molecular characteristics.

First, the researchers observed that EBV-positive tumours displayed a high frequency of mutations in the PIK3CA gene, which codes for a component of a protein, PI3-kinase, which is essential for cell growth and division and many other cellular activities that are important in cancer. Although 80 percent of EBV-positive tumours harboured a protein-changing alteration in PIK3CA, PIK3CA mutations were found in 3 percent to 42 percent of tumours of the other gastric cancer subtypes. The scientists suggested that EBV-positive tumours might respond to PI3-kinase inhibitors, some of which are in the early stages of testing in clinical trials but are not yet approved by the U.S. Food and Drug Administration for general use.

Some tumours in the EBV-positive subgroup also showed more gene copies being produced in a chromosomal region that contains the JAK2 gene. The JAK2 protein facilitates cell growth and division, and the increased expression of JAK2 may inappropriately activate cell growth. The amplified region also contains the genes for two proteins, PD-L1 and PD-L2, which suppress immune responses; their increased expression may help tumours escape destruction by the immune system. The investigators suggested that these findings support the evaluation of JAK2 inhibitors and PD-L1/2 antagonists for the treatment of EBV-positive gastric cancers.

And the EBV-positive subgroup showed a far higher prevalence of DNA hypermethylation than any other cancer subtype reported by TCGA researchers. Methylation is the process of adding methyl groups to DNA, which reduces gene expression. Hypermethylation occurs when this mechanism continues aberrantly, quieting genes that should be active. In the EBV-positive tumour subgroup, hypermethylation was most often observed in the promoter regions of genes, which would prevent the expression of the genes.
‘Gaining these insights into the connection between EBV and gastric cancer is the type of groundbreaking research that NIH is pleased to be a part of. We look forward to the potential clinical implications of this discovery,’ said NIH Director Francis S. Collins, M.D., Ph.D. The Cancer Genome Atlas