Decoding neuroblastoma microenvironment

MCT Research Talks – 24th April 2017

The main challenge in treating high-risk neuroblastoma is to combat tumour metastasis and development of resistance to multiple chemotherapeutic drugs. In the native tissue, cancer cells are surrounded by a three-dimensional (3D) microenvironment which provides biological and physical support and determines disease initiation, progression, patient prognosis and response to treatment. The conventional two-dimensional (2D) cell culture lacks this feature resulting in discrepancies between in vitro and in vivo results. Current neuroblastoma studies employ either 2D cell culture systems or murine models or alternatively a mix of both.

In collaboration with Dr Caroline Curtin and Prof Fergal O’Biren (TERG), we decided to bridge the gap between 2D culture and in vivo tumours in neuroblastoma research by developing a tissue-engineered cell culture model of neuroblastoma. This project is supported by a pilot grant from Neuroblastoma UK.

To understand what signalling pathways are activated in 2D, 3D and in vivo neuroblastoma models, we decided to look closer at the differences between conventional 2D neuroblastoma cells and their xenografts. This way we hope to find those targets that are activated in both tumour microenvironment and the 3D tissue engineered models. Ciara and Larissa have begun this search by profiling xenograft samples with a panel of antibodies. Ciara became particularly fascinated by the elevated levels of c-jun, TCF1 and LEF1 in cisplatin-resistant neuroblastoma xenografts suggesting that the development of cisplatin resistance in neuroblastoma may be accompanied by activation of the wnt/b-catenin pathway in vivo. Larissa identified that cisplatin-resistant neuroblastoma cells secrete chromogranin A (CgA) at levels higher that cisplatin-sensitive cells. CgA levels also correlated with increased vascularisation and volume of murine orthotopic neuroblastoma xenografts. Altogether it suggests that CgA can be used as a marker of neuroblastoma cell growth both in vitro and in vivo.

Olga Piskareva

Characterisation of Novel FCγRIIa Inhibitors

MCT Research Talks – 10th, April 2017

Research talks were presented by Sheila Zarros, Tatyana Devine, Afnan Ali and Padraig Norton. Tatyana and Sheila were talking about challenges in the characterisation of novel FCγRIIa inhibitors.

Fc receptors are a widely distributed family of receptors that mediate cellular responses to antibodies or immunoglobulins (Ig). The Fc gamma receptor II, FcgRII (also known as CD32) is a low-affinity receptor for Fc portion of immunoglobulin G (IgG) and has two isoforms FcgRIIa and b. Fcg RIIa is widely expressed by human innate immune cells and is the only Fc gamma receptor found on human platelets.

Our group and others have demonstrated the significance of this receptor in the activation of platelets by bacteria, suggesting that it could be an important target in the treatment of sepsis. Its implications in rheumatoid arthritis, cancer pathogenesis, allergic reactions and flu virus-induced thrombocytopenia were also demonstrated.

Our project is focused on characterisation of novel small molecule compounds designed for targeting FcgRIIa receptor’s IgG binding site to inhibit bacteria-induced platelet aggregation in primary human plasma and investigation of their interactions with the FcgRIIa using surface plasmon resonance technology.

Afnan Ali reported on the role of the Fc gamma Receptor IIa (FcγRIIa) in platelet activation. Platelets express the FcγRIIa and this receptor has been identified as a key receptor in bacterial activation of platelets leading to thrombocytopenia and platelet activation. The aim of this study was to identify drugs that could be re-purposed for the treatment of sepsis and immune-mediated thrombocytopenia. We identified 42 drugs predicted to inhibit binding of IgG1 to the FcγRIIa using virtual high throughput screening. This included 20 antibacterial agents, 3 anti-fungals, 3 antiviral agents, 7 antineoplastics and 3 immunosuppressives. A selection of drugs were tested for inhibition of platelet adhesion to IgG, S. aureus-induced platelet aggregation and assessed for platelet activation. This work has identified multiple drugs that have potential to be to be repositioned for thrombocytopenia, sepsis and autoimmune disorders, as well as providing a possible mechanism of action to explain the immunosuppressive effects of some anti-neoplastics and immunosuppressive drugs.

Japan Society for Promotion of Science – Short-term post-doctoral fellowship

Following a workshop conducted at Hoshi University, Tokyo, Japan organized through the ISCA-Japan initiative funded by SFI in October, 2015 a successful collaborative initiative was established between Dr. Sudipto Das (MCT, RCSI) and Prof. Hiroko Ikeda (Department of Neurophysiology, Hoshi University) to investigate the role of epigenetic modifications like DNA methylation in driving a neuronal dysfunction phenotype associated with Diabetes mellitus (DM). Moving this collaboration forward with support from his collaborators at Hoshi University Dr. Sudipto Das has recently received a prestigious short-term post-doctoral fellowship to further his work at Hoshi University from the Japan Society for Promotion of Science (JSPS), which would essentially cover travel, subsistence and a research consumable allowance of 562,000 Japanese Yen. As a part of this fellowship, Dr. Das will travel to Japan for a period of 1.5 months in January 2018. The successful completion of the proposed project as a part of this proposal will for the first time allow the scientific community to understand as to how epigenetic modifications like DNA methylation impact on neurological dysfunction in endocrine

The successful completion of the proposed project as a part of this proposal will for the first time allow the scientific community to understand as to how epigenetic modifications like DNA methylation impact on neurological dysfunction in endocrine related disorders such as DM, thus opening up avenues to utilize this modification to potentially predict such conditions in DM patients.

Sudipto Das

The circadian protein BMAL1 in myeloid cells is a negative regulator of allergic asthma

Asthma is of particular relevance to the area of circadian control of immunity, since it is a disease with very strong clinical evidence demonstrating regulation by circadian variation. Airway hypersensitivity and asthma attacks are more common at night in humans. The molecular basis for this is unknown and no model of asthma in animals with genetic distortion of the molecular clock exists.

Asthma is under strong circadian variation. Asthma symptoms worsen at night, particularly in the early hours of the morning. Lung function fluctuates in healthy individuals over 24 h period and these fluctuations are even more pronounced in asthmatics.

In this study, we showed that mice lacking the main clock transcription factor BMAL1 in myeloid cells have increased lung inflammation demonstrated by higher numbers of eosinophils and increased IL-5 (key pathogenic cytokine in asthma that recruits eosinophils).This suggests that Bmal1 is a potent negative regulator, in myeloid cells in the context of allergic asthma. Our findings might explain the increase in asthma incidents during the night in humans when BMAL1 expression is low.

Dr. Zbigniew Zaslona from TCD (pictured here) was the lead author on the study. Both Dr. Annie Curtis (MCT) and Prof. Luke O’Neill (TCD) were joint senior authors on the paper.

The circadian protein BMAL1 in myeloid cells is a negative regulator of allergic asthma.

Zaslona Z, Case S, Early JO, Lalor SJ, McLoughlin RM, Curtis AM*, O’Neill LA* – Both authors contributed equally to this study.

Am J Physiol Lung Cell Mol Physiol. 2017 Mar 23:ajplung.00072.2017. doi: 10.1152/ajplung.00072.2017. [Epub ahead of print]