DUSP1

Researchers from the University of Liverpool have identified and characterised antibody fragments that target free light chain (LC) to help treat patients living with AL amyloidosis. The new research, published in The FEBS Journal , could help to stabilise and prevent their LC antibody aggregation and could also be applied to other forms of the condition, including Alzheimer’s disease. Estimated to affect five to 12 people per million worldwide every year, amyloidosis is a group of rare, serious conditions caused by the abnormal folding of amyloid proteins that build up in tissue throughout the body. Currently the most common but rare and severe form of the condition, AL amyloidosis occurs when abnormal LC proteins in the body mutate and gather on the tissues and organs, including the heart, kidneys, liver, spleen, nervous system and digestive tract. The current treatment can be difficult to tolerate “and diagnosed patients often have a poor prognosis, with the estimated survival time being between six months and three  years,” explained Dr Jill Madine, senior lecturer, biochemistry, cell and systems biology, University of Bristol. Using phage-display screening methods – a form of high-throughput screening that allows large numbers of peptide segments to be screened for binding to a target – researchers identified a variable-heavy (VH) domain called VH1, targeted towards FLCs SMA, LEN and REC. Each LC is composed of two tandem immunoglobulin domains: one constant (CL) domain and one variable domain (VL), which is important for binding antigen. Results showed that VH1 was able to bind and kinetically stabilise LCs, which improved the stability of the inhibition of fibril formation of SMA by reducing aggregation to baseline levels and mimicking the dimeric antigen binding site of the native Ig molecule and SMA homodimeric structure. After testing in three participating AL amyloidosis patients, the FLC concentration was found to be significantly raised, while only SMA and REC were found to be amyloidogenic in vevo. The findings suggest that VH1 has the potential to therapeutically target AL amyloidosis by stabilising native LCs, improving its stability and preventing the aggregation of VH1 alone. Madine commented: “We are excited by this finding, which has potential to provide a much-needed treatment for people diagnosed with the condition.”

A recent study uncovers a pathway used during normal wound healing that has the potential to reverse IPF. he most common type of lung fibrosis -- scarring of the lungs -- is idiopathic, meaning of unknown cause. Researchers are urgently trying to find ways to prevent or slow idiopathic pulmonary fibrosis (IPF) and related lung conditions, which can cause worsening shortness of breath, dry cough, and extreme fatigue. Average survival following diagnosis of IPF is just three to five years, and the disease has no cure. A recent U-M study from a team led by Sean Fortier, M.D. and Marc Peters-Golden, M.D. of the Division of Pulmonary and Critical Care Medicine at U-M Medical School uncovers a pathway used during normal wound healing that has the potential to reverse IPF. Using a mouse model, they simulated IPF by administering bleomycin, a chemotherapy agent that causes cell injury and confirmed that the resulting lung scarring resolved itself over the span of about six weeks. Because of this, "studying fibrosis is kind of tough," said Fortier. "If we're going to give experimental drugs to try and resolve fibrosis, we have to do it before it resolves on its own. Otherwise, we will not be able to tell if the resolution was the action of the drug or natural repair mechanisms of the body." However, he said, "there's actually a lot to learn about how the mouse gets better on its own. If we can learn the molecular mechanisms by which this occurs, we may uncover new targets for IPF." The process by which lung injury either leads to healing or fibrosis relies in part on what happens to a cell called a fibroblast, which forms connective tissue. During injury or illness, fibroblasts are activated, becoming myofibroblasts that form scar tissue by secreting collagen. When the job is done, these fibroblasts must be deactivated, or de-differentiated, to go back to their quiet state or undergo programmed cell death and be cleared. "This is the major distinction between normal wound healing and fibrosis -- the persistence of activated myofibroblasts," explained Fortier. That deactivation is controlled by molecular brakes. The study examined one of these brakes, called MKP1 -- which the team found was expressed at lower levels in fibroblasts from patients with IPF. By genetically eliminating MKP1 in fibroblasts of mice after establishing lung injury, the team saw that fibrosis continued uncontrolled. "Instead of at day 63, seeing that nice resolution, you still see fibrosis," said Fortier. "We argued by contradiction: when you knock out this brake, fibrosis that would otherwise naturally disappear, persists and therefore MKP1 is necessary for spontaneous resolution of fibrosis." They performed several additional studies using CRISPR techniques to demonstrate how MKP1 applies the brakes, mainly by deactivating the enzyme p38α, which is implicated in a cell's reaction to stress. Furthermore, they demonstrated that neither of the two current FDA approved drugs for lung fibrosis, pirfenidone and nintedanib, are able to turn off myofibroblasts. "That's totally in keeping with the fact that they do slow the progression, but they don't halt or reverse disease," said Fortier. Fortier hopes the discovery that this pathway reverses fibrosis leads to exploration of additional brakes on fibrosis. "So much work on fibrosis has focused on how we can prevent it, but when a patient presents to my clinic with a dry cough, shortness of breath, and low oxygen as a result of underlying IPF, the scarring is already present. Of course, we'd love a way to prevent the scarring from getting worse, but the Holy Grail is to reverse it."

Cancer is a disease of survival: cells grow when they shouldn’t. So unsurprisingly, many proteins and enzymes that prevent cell death are abnormally active in tumors. In fact, apoptosis evasion is considered one of the “hallmarks of cancer”, so it was with great excitement in 2012 that scientists discovered ferroptosis: a new form of regulated cell death that is strongly evaded by cancer. Ferroptosis results from an increase in toxic lipid peroxides owing to high levels of iron and specific poly-unsaturated fatty acids. Cancer tends to upregulate iron transporters to grow faster, so it is no surprise that it is quite susceptible to ferroptosis and very dependent on its suppression. After a decade of ferroptosis research, we now know many of the important genes that prevent ferroptosis, many of which cancer relies on to grow, proliferate, and survive. The most well-studied enzyme is GPX4: a protein that reduces toxic lipid peroxides into inert lipid alcohols, evading ferroptosis. Many scientists across the country have linked GPX4 to certain cancer contexts such as mesenchymal lineages in pancreatic cancer, osteosarcomas, and triple negative breast cancer. At Arpeggio, we’ve used our GRETATM technology to identify an extremely selective and potent GPX4 inhibitor. Like apoptosis, ferroptosis leaves an extremely identifiable transcriptional fingerprint on a cell. Certain genes like HMOX1, OSGIN1, and DUSP1 are unique transcriptional responses to the induction of ferroptosis. We can leverage this transcriptional signature to screen for compounds that uniquely and selectively turn on this pathway in cancer (Figure 1). After a large chemotranscriptomic small molecule screen using GRETATM, we identified a hit compound that both binds and inhibits GPX4 (a protein many drug discovery and development consider “undruggable" due to its greasy globular protein structure). After medicinal chemistry optimization, our current lead small molecule induces robust tumor growth inhibition in multiple mouse models of cancer including pancreatic cancer and sarcoma. Early toxicology studies of our lead GPX4 inhibitor indicate a safe and tolerated profile with no signs of body weight loss or impairment in either kidney or liver function (Figure 2). Recent studies have emerged suggesting that ferroptosis plays a synergistic role in activating the immune system to fight cancer. CD8+ T-cells are an extremely well-studied subset of our immune system that are responsible for clearing and attacking foreign bodies like viruses but, when activated by medicine such as Keytruda, can also recognize and fight cancer. CD8+ T-cells fight cancer, in part, by expressing high extracellular levels of IFN-y (Figure 3). Recent work suggests that IFN-y actually suppresses system-Xc expression, which depletes cancer cells of glutathione and ultimately renders them more susceptible to Ferroptosis. Using our first-in-class GPX4 inhibitor, we’ve demonstrated robust anti-tumor activity in combination with anti-PDL1 in mouse models harboring an intact immune system, paving the way for a novel combination opportunity to bring medicine to millions of patients who do not respond to drugs like Keytruda. ‍