Research news in brief

Stopping cancer metastasis

Spanish researchers have found a specific type of cell in human oral carcinoma that plays an important role in promoting cancer metastasis. The identified cell type expresses high levels of the fatty acid receptor, CD36, and blocking this receptor with antibodies made the cancers less likely to spread in mice. Salvador Aznar Benitah and colleagues from the Barcelona Institute of Science and Technology also noticed that, if the cancer had already metastasised, the metastases notably shrank or disappeared. The findings, reported online in Nature, also highlight a prominent role for dietary lipids in cancer metastasis. Metastasis is the main cause of cancer-related death, but for most cancers, the identity of the cells that trigger the phenomenon is unknown. This makes the development of anti-metastatic therapies difficult. The CD-36 receptor antibody had a metastasis-blocking effect, not just for human oral carcinoma cells injected into mouse cancer models, but also for human melanoma and breast cancer cells. This finding suggests that there may be a general mechanism underlying tumour metastasis, and hints that CD36-blocking therapies might have widespread application. Clinically, the presence of these CD36-expressing cells correlates with poor prognosis for many different carcinomas, and in mouse models, a high fat diet appears to boost the cells’ metastatic potential.

Faulty brain waves increase Alzheimer’s protein

US researchers have found that disrupted electrical signalling in the brain may contribute to the accumulation of amyloid-β (Aβ) protein, according to a study in mice published in Nature. Accumulation of amyloid-β is a hallmark of Alzheimer’s disease (AD). The study showed that restoring the electrical oscillations generated by neural circuits reduced Aβ formation and activated immune cells to clear the protein from the brain. When networks of neurons are activated in a synchronised manner in the brain, they generate electrical oscillations. If the frequency of these brain rhythms averages 40 Hz per second, they are referred to as gamma oscillations. Gamma oscillations are thought to be important for higher cognitive functions, and sensory responses and previous studies have reported that they are disrupted in various neurological diseases, including AD. However, how gamma oscillations affect pathology has remained unclear. The researchers from the Massachussetts Institute of Technology recorded the neural activity of mice in a well established model of AD to show that gamma oscillations declined before Aβ accumulated to form amyloid plaques and before cognitive decline. They then used an optogenetic (light-mediated) technique to directly stimulate neurons in the hippocampus of AD model mice to produce gamma oscillations. This was found to reduce Aβ production in this region of the brain and led to the activation of microglia – the brain’s immune cells – to clear Aβ. The authors devised a non-invasive approach to induce gamma oscillations in the mouse primary visual cortex by flickering LED lights at 40 Hz. This non-invasive technique reduced Aβ levels in the visual cortex of mice with early stages of AD and decreased the amount of amyloid plaque in the visual cortex of aged mice at a later stage of disease. Taken together, the observations suggested that the reduction of total Aβ levels might be mediated by both decreased Aβ formation and increased amyloid clearance by microglia. However, the authors noted that using gamma oscillations therapeutically would constitute a fundamentally different approach to prior AD therapies, so further study was needed to determine whether this approach would work in humans.

Concurrent tobacco and cannabis use

Researchers from the University of Newcastle and the University of New South Wales have found that regular cannabis use was significantly associated with lower motivation to quit smoking in a sample of socio-economically disadvantaged smokers, according to a study published in Health Education Research (abstract only). A survey was conducted in 2013 and 2014 with current tobacco smokers receiving aid from two community service organisations in NSW. At least weekly cannabis use for the month prior to the survey, motivation to quit tobacco and intentions to quit tobacco were measured in 369 participants (77% consent rate). Concurrent tobacco and cannabis use was reported by 19% (n = 71) of the sample, and of these users, 100% reported simultaneous use. Although regular cannabis use was significantly associated with lower motivation to quit tobacco, it was not significantly associated with intentions to quit tobacco in the next 30 days. Concurrent cannabis use was common in disadvantaged smokers and may play a role in decreased motivation to quit tobacco; however, it did not appear to be associated with intentions to quit in a sample of disadvantaged smokers.

Improvements in use of PPIs in older Australians

National programs designed to reduce the overall use of proton pump inhibitors (PPIs) and increase the use of low-strength PPIs in older Australians appear to be bearing fruit, according to a study published in the International Journal for Quality in Health Care (abstract only). According to the researchers from the Sansom Institute for Health Research at the University of South Australia, and the Centre for Medicine Use and Safety at Monash University, national, multifaceted interventions to improve PPI use targeting clinicians and consumers were conducted by the Australian Government Department of Veterans’ Affairs (DVA) Veterans’ MATES program and NPS MedicineWise in April 2004, June 2006, May 2009 and August 2012. The researchers conducted an interrupted time series analysis using administrative health claims data from the DVA for all veterans and dependents who received PPIs between January 2003 and December 2013. Interventions in 2004, 2006, 2009 and 2012 slowed the rate of increase in PPI use significantly, with the 2012 intervention resulting in a sustained 0.04% decrease in PPI use each month. The combined effect of all four interventions was a 20.9% relative decrease in PPI use (95% CI, 7.8–33.9%) 12 months after the final intervention. The four interventions also resulted in a 42.2% relative increase in low strength PPI use (95% CI, 19.9–64.5%) 12 months after the final intervention. “Interventions to improve PPI use should incorporate regular repetition of key messages to sustain practice change,” the authors concluded.

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