A simple, ultrasensitive microRNA sensor developed by researchers from the School of Science at Indiana University-Purdue University Indianapolis, the IU School of Medicine and the IU Melvin and Bren Simon Cancer Center holds promise for the design of new diagnostic strategies and, potentially, for the prognosis and treatment of pancreatic and other cancers.

In a study the IUPUI researchers describe their design of the novel, low-cost, nanotechnology-enabled reusable sensor. They also report on the promising results of tests of the sensor’s ability to identify pancreatic cancer or indicate the existence of a benign condition by quantifying changes in levels of microRNA signatures linked to pancreatic cancer.

‘We used the fundamental concepts of nanotechnology to design the sensor to detect and quantify biomolecules at very low concentrations,’ said Rajesh Sardar, Ph.D., who developed the sensor. ‘We have designed an ultrasensitive technique so that we can see minute changes in microRNA concentrations in a patient’s blood and confirm the presence of pancreatic cancer.’ Sardar is an assistant professor of chemistry and chemical biology in the School of Science at IUPUI and leads an interdisciplinary research program focusing on the intersection of analytical chemistry and the nanoscience of metallic nanoparticles.

‘If we can establish that there is cancer in the pancreas because the sensor detects high levels of microRNA-10b or one of the other microRNAs associated with that specific cancer, we may be able to treat it sooner,’ said Murray Korc, M.D., the Myles Brand Professor of Cancer Research at the IU School of Medicine and a researcher at the IU Simon Cancer Center. Korc worked with Sardar to improve the sensor’s capabilities and led the testing of the sensor and its clinical uses as well as advancing the understanding of pancreatic cancer biology.

‘That’s especially significant for pancreatic cancer, because for many patients it is symptom-free for years or even a decade or more, by which time it has spread to other organs, when surgical removal is no longer possible and therapeutic options are limited,’ said Korc. ‘For example, diagnosis of pancreatic cancer at an early stage of the disease followed by surgical removal is associated with a 40 percent five-year survival. Diagnosis of metastatic pancreatic cancer, by contrast, is associated with life expectancy that is often only a year or less.

‘The beauty of the sensor designed by Dr. Sardar is its ability to accurately detect mild increases in microRNA levels, which could allow for early cancer diagnosis,’ Korc added.

Over the past decade, studies have shown that microRNAs play important roles in cancer and other diseases, such as diabetes and cardiovascular disorders. The new IUPUI nanotechnology-based sensor can detect changes in any of these microRNAs.

The sensor is a small glass chip that contains triangular-shaped gold nanoparticles called ‘nanoprisms.’ After dipping it in a sample of blood or another body fluid, the scientist measures the change in the nanoprism’s optical property to determine the levels of specific microRNAs.

‘Using gold nanoprisms may sound expensive, but it isn’t because these particles are so very tiny,’ Sardar said. “It’s a rather cheap technique because it uses nanotechnology and needs very little gold. $250 worth of gold makes 4,000 sensors. Four thousand sensors allow you to do at least 4,000 tests. The low cost makes this technique ideal for use anywhere, including in low-resource environments in this country and around the world.’ IUSM

Each year approximately 1 in 1,000 pregnant women will experience peripartum cardiomyopathy, an uncommon form of often severe heart failure that occurs in the final month of pregnancy or up to five months following delivery. But the cause of peripartum cardiomyopathy has been largely unknown – until now. Researchers from the Perelman School of Medicine at the University of Pennsylvania analysed the genetic variants that have been associated with another form of inherited cardiomyopathy, and determined that peripartum cardiomyopathy is often the result of a genetic mutation.

Researchers analysed 43 genes in 172 women who experienced peripartum cardiomyopathy, and found that 15 percent of the group had genetic mutations, usually in their TTN gene, which encodes the instructions for making the Titin protein. This protein—named after the Greek gods, Titans—is the largest protein in the body and directly affects the heart’s ability to contract and relax. Of the women analysed, 26 were identified to have mutations on the TTN gene, an effect that is significantly higher than any other reported finding for the cause of peripartum cardiomyopathy.

“Until now, we had very little insight into the cause of peripartum cardiomyopathy,” said the study’s senior author, Zoltan Arany, MD, PhD, an associate professor of Cardiovascular Medicine. “There had been theories that it was linked to a viral infection, or paternal genes attacking the mother’s circulatory system, or just the stresses of pregnancy. However, this research shows that a mutation in the TTN gene is the cause of a significant number of peripartum cardiomyopathies, even in women without a family history of the disease.”

This sizable percentage indicates that peripartum cardiomyopathy is caused by genetic mutations. The same mutations are also present in many who experienced dilated cardiomyopathy, a condition in which the heart’s ability to pump blood is decreased when the main pumping chamber becomes weak and enlarged. This is similar to peripartum cardiomyopathy but most often occurs in older patients. However, the two diseases are not the same. For example, a woman with the genetic mutation for dilated cardiomyopathy will not always experience peripartum cardiomyopathy, and women with the peripartum cardiomyopathy mutation will not always experience dilated cardiomyopathy later in life. How the same mutations can lead to different conditions in different people remains an unanswered question.

Arany added, “these findings will certainly inform future peripartum cardiomyopathy research, with possible implications on genetic testing and preventive care. Though, more research is unquestionably needed. We’re continuing to follow these women and we’re gathering data for hundreds of others around the world, with the goal of identifying the cause of peripartum cardiomyopathy in the remaining 85 percent of women with this condition, and ultimately using what we learn to improve the care of these women and their newborns.” Penn Medicine News

Many cancers include increased copies of the gene MET. But in which cases is MET driving the cancer and in which do these increased copies happen to ‘ride along’ with other molecular abnormalities that are the true cause of the disease? The answer influences whether a tumour will respond to drugs that inhibit MET, like crizotinib. A University of Colorado Cancer Center study sheds light on the best method to determine the threshold at which MET amplification becomes clinically relevant.

‘Generally, there are two ways that the number of copies of the MET gene can be increased: The tumour can make multiple copies of the entire chromosome on which it sits — chromosome 7 — or it can amplify just the MET region. In the first case, MET is unlikely to be the specific driver of the cancer’s biology, it may just be a ride along. But if the MET region is amplified separate from the rest of the chromosome, this would suggest that the MET gene is indeed the area of specific importance to the cancer,’ says Sinead Noonan, MD, investigator at the CU Cancer Center, senior thoracic oncology fellow at the CU School of Medicine, and the study’s first author.

The goal of the current study was to find evidence supporting the above hypothesis and to identify a group of MET-driven patients in which crizotinib would be effective.

To do so, Noonan worked with Marileila Garcia, PhD, CU Cancer Center investigator and professor of Oncology at the CU School of Medicine, who assessed the genetics of over 1,000 lung cancer patients. Using the low level criteria commonly used for defining an increase in MET copy number, independent of whether it was increased by increasing the overall number of copies of the chromosome or just that region of the chromosome, 14.4 percent of these samples were positive for MET copy number gain. The group then looked at another measure, comparing MET copy number to the number of chromosome 7 centromeres — the center point of the chromosome — which allowed them to see how specifically MET was amplified in comparison with the chromosome as a whole. When the low level criteria for defining an increase in MET copy number using the ratio of MET to centromere 7 was used, only 4.5 percent of these cases were positive.

Now the question was what ratio of MET to centromere 7, exactly, defined patients whose tumours were driven by this gene amplification and so would be most susceptible to MET inhibition via crizotinib.

‘There is almost always only one driver abnormality in any given tumour,’ Noonan says. But in 47 percent of the tumours defined by the minimal MET-to-centromere-7 ratio criteria, the group was able to identify other known genetic drivers, including mutations or gene rearrangements in EGFR, KRAS, BRAF, ALK, ERBB2, RET or ROS1.

‘Strikingly, as we looked at cases with higher and higher MET positivity, the degree of overlap with other known drivers decreased,’ Noonan says. In other words, as the MET-to-centromere-7 ratio increased, the group was less likely to find any other candidates for the cause of the cancer.

A group completely free from overlap with other known cancer drivers was only found in the group in which MET overbalanced centromere 7 by 5 times. Using the other common method of simply counting MET, independent of the ratio, it was impossible to find a group without additional known genetic driver.

‘I think these data really help to solidify MET-to-centromere ratio as the better measure for defining a lung cancer driven by MET copy number,’ says D. Ross Camidge, MD, PhD, Joyce Zeff Chair in Lung Cancer Research at the CU Cancer Center and the senior author of the study. ‘While the highest ratio only occurs in 0.34 percent of cases, it has clearly been associated with responses to crizotinib approaching 70 percent. However, responses have also been seen at lower ratios. Overall, if we look across all levels of MET-ratio positive cases but exclude those with other identifiable drivers we can identify a group representing 2.4 percent of adenocarcinomas which is ripe for further investigation as potential MET-sensitive subtypes of lung cancer.’ ScienceDaily

Colon cancer is one of the leading causes of cancer-related deaths worldwide, and researchers are hard at work to understand the disease’s complex molecular underpinnings. In a new study researchers from the University of Pennsylvania describe two related genes in the Musashi family that are required for colon cancer to develop, and that may be useful targets for effective treatment.

The work, led by Christopher Lengner, an assistant professor in the Department of Biomedical Sciences in Penn’s School of Veterinary Medicine, challenges a paradigm in the field whereby activation of a molecular signalling cascade known as the Wnt pathway is held responsible for the majority of colon cancer cases in humans. The new findings suggest that the Musashi genes, MSI1 and MSI2, act in a path parallel to the Wnt pathway and may be equally important for driving colon cancer.

The work also indicates that the two genes, which encode RNA-binding proteins, are functionally redundant.

“The data suggest that either MSI protein is sufficient to support cancer,” Lengner said. “If you want to use these proteins as a drug target, you’d have to design a drug that will inhibit both of them.”

While researchers have known for some time that MSI1 was expressed in colon cancer, the mechanism by which it acted and its functional requirement for the disease were not well understood. The related protein MSI2 had not been rigorously examined in the context of colon cancer until earlier this year, when a paper by Lengner and colleagues found that it could trigger activation of cellular metabolic processes that fuel cancerous cells in the intestines.

“Considering the expression patterns of these two proteins during homeostasis, or normal conditions, you would expect their function when they were hijacked by cancer could be similar in supporting tumour growth,” said Ning Li, first author on the study and a postdoctoral fellow in Lengner’s lab.

The current work took both proteins into account. Whereas the prior paper found that MSI2 was consistently overexpressed in intestinal cancer tissue, Lengner and colleagues found that MSI1 was more variable, overexpressed in some samples and under-expressed in others, compared to normal tissue. When they bred mice in which they could induce overexpression of MSI1 in the intestine, the cells of the intestine began to divide rapidly and lost their ability to differentiate, just as mice with inducible overexpression of MSI2 had.

They found that inducing MSI1 turned on a similar set of genes as MSI2 overexpression did, including genes related to RNA processing and translation, necessary processes for manufacturing the required components for cancer’s rapid cell growth. The analysis also revealed that activating MSI1 caused a set of genes to be expressed that match the effect of losing the function of APC, a tumour suppressor gene that is inactivated in more than 80 percent of cases of human colon cancer.

As they had done with MSI2, the researchers also conducted an experiment that reveals the RNA transcripts to which MSI1 binds, and they found high levels of similarity to the set of transcripts bound by MSI2. Notably, both proteins bind tumor suppressors, such as Pten, which activates cellular metabolism through a protein complex called mTORC1. Further experiments confirmed MSI1 promoted mTORC1 activity.

“We concluded that these proteins are functioning in the same pathways and acting redundantly not only because they are binding similar proteins but also because when you overexpress them, the phenotype is identical,” Lengner said. “They appear to have identical oncogenic properties.” Penn News