Great news, we have a new co-author publication out in the journal Oncogene! The work was lead by Professor Neil Watkins, and is titled “The tumor suppressor Hic1 maintains chromosomal stability independent of Tp53”.
You can access the full article here [Link]
ABSTRACT: Hypermethylated-in-Cancer 1 (Hic1) is a tumor suppressor gene frequently inactivated by epigenetic silencing and loss-of- heterozygosity in a broad range of cancers. Loss of HIC1, a sequence-specific zinc finger transcriptional repressor, results in deregulation of genes that promote a malignant phenotype in a lineage-specific manner. In particular, upregulation of the HIC1 target gene SIRT1, a histone deacetylase, can promote tumor growth by inactivating TP53. An alternate line of evidence suggests that HIC1 can promote the repair of DNA double strand breaks through an interaction with MTA1, a component of the nucleosome remodeling and deacetylase (NuRD) complex. Using a conditional knockout mouse model of tumor initiation, we now show that inactivation of Hic1 results in cell cycle arrest, premature senescence, chromosomal instability and spontaneous transformation in vitro. This phenocopies the effects of deleting Brca1, a component of the homologous recombination DNA repair pathway, in mouse embryonic fibroblasts. These effects did not appear to be mediated by deregulation of Hic1 target gene expression or loss of Tp53 function, and rather support a role for Hic1 in maintaining genome integrity during sustained replicative stress. Loss of Hic1 function also cooperated with activation of oncogenic KRas in the adult airway epithelium of mice, resulting in the formation of highly pleomorphic adenocarcinomas with a micropapillary phenotype in vivo. These results suggest that loss of Hic1 expression in the early stages of tumor formation may contribute to malignant transformation through the acquisition of chromosomal instability.
Great news, we have published a co-authored paper entitled ‘Ensa controls S-phase length by modulating Treslin levels’ in the prestigious journal ‘Nature Communications’. This work was started back in 2011 when I was a Post-Doc in the laboratory of Anna Castro in France. It’s exciting to see those inital discoveries transition into the finished paper.
The article is Open Access and free to download, which you can do so here: http://www.nature.com/articles/s41467-017-00339-4
The Greatwall/Ensa/PP2A-B55 pathway is essential for controlling mitotic substrate phos- phorylation and mitotic entry. Here, we investigate the effect of the knockdown of the Gwl substrate, Ensa, in human cells. Unexpectedly, Ensa knockdown promotes a dramatic extension of S phase associated with a lowered density of replication forks. Notably, Ensa depletion results in a decrease of Treslin levels, a pivotal protein for the firing of replication origins. Accordingly, the extended S phase in Ensa-depleted cells is completely rescued by the overexpression of Treslin. Our data herein reveal a new mechanism by which normal cells regulate S-phase duration by controlling the ubiquitin-proteasome degradation of Treslin in a Gwl/Ensa-dependent pathway.
Great news we have a new co-author publication in Oncogene!
This work was in collaboration with Prof. Neil Wakins here at the Garvan Institute and focuses on the role of Hedgehog (Hh) signaling in small cell lung cancer (SCLC). Small cell lung cancer is a common, aggressive malignancy with universally poor prognosis.
Full details can be found here [link]
TITLE: “The role of canonical and non-canonical Hedgehog signaling in tumor progression in a mouse model of small cell lung cancer”
Hedgehog (Hh) signaling regulates cell fate and self-renewal in development and cancer. Canonical Hh signaling is mediated by Hh ligand binding to the receptor Patched (Ptch), which in turn activates Gli-mediated transcription through Smoothened (Smo), the molecular target of the Hh pathway inhibitors used as cancer therapeutics. Small cell lung cancer (SCLC) is a common, aggressive malignancy with universally poor prognosis. Although preclinical studies have shown that Hh inhibitors block the self-renewal capacity of SCLC cells, the lack of activating pathway mutations have cast doubt over the significance of these observations. In particular, the existence of autocrine, ligand-dependent Hh signaling in SCLC has been disputed. In a conditional Tp53;Rb1 mutant mouse model of SCLC, we now demonstrate a requirement for the Hh ligand Sonic Hedgehog (Shh) for the progression of SCLC. Conversely, we show that conditional Shh overexpression activates canonical Hh signaling in SCLC cells, and markedly accelerates tumor progression. When compared to mouse SCLC tumors expressing an activating, ligand-independent Smo mutant, tumors overexpressing Shh exhibited marked chromosomal instability and Smoothened-independent upregulation of Cyclin B1, a putative non-canonical arm of the Hh pathway. In turn, we show that overexpression of Cyclin B1 induces chromosomal instability in mouse embryonic fibroblasts lacking both Tp53 and Rb1. These results provide strong support for an autocrine, ligand-dependent model of Hh signaling in SCLC pathogenesis, and reveal a novel role for non-canonical Hh signaling through the induction of chromosomal instability.
It was a great pleasure to be apart of this amazing research by Claire Venin and Paul Timpson, which was recently published in Science Translational Medicine, one of the very best journals in the world.
Here is a brief intro into the research.
ROCK-ing pancreatic cancer to the core
Pancreatic cancer, one of the most deadly and difficult-to-treat tumor types in patients, usually has a dense stroma that can be difficult for drugs to penetrate. Stromal characteristics can also affect multiple other aspects of tumor biology, including metastatic spread, vascular supply, and immune response. Vennin et al. used Fasudil, a drug that inhibits a protein called ROCK and is already used for some conditions in people, to demonstrate the feasibility including short-term tumor stroma remodeling as part of cancer treatment. In genetically engineered and patient-derived mouse models of pancreatic cancer, priming with Fasudil disrupted the tumors’ extracellular matrix and improved the effectiveness of subsequent treatment with standard-of-care chemotherapy for this disease.
If you would like to know more you can read the full article here:
Vennin, C. et al. 2017. Transient tissue priming via ROCK inhibition uncouples pancreatic cancer progression, sensitivity to chemotherapy, and metastasis. Science translational medicine. 9, 384 (Apr. 2017).
Great news, we have had a co-author review published in the Journal of Molecular and Cellular Biology.
You can check out the full review here.
The major cause of death from breast cancer is not the primary tumour, but relapsing, drug-resistant, metastatic disease. Identifying factors that contribute to aggressive cancer offers important leads for therapy. Inherent defense against carcinogens depends on the individual molecular make-up of each person. Important molecular determinants of these responses are under the control of the mouse double minute (MDM) family: comprised of the proteins MDM2 and MDM4. In normal, healthy adult cells, the MDM family functions to critically regulate measured, cellular responses to stress and subsequent recovery. Proper function of the MDM family is vital for normal breast development, but also for preserving genomic fidelity. The MDM family members are best characterized for their negative regulation of the major tumour suppressor p53 to modulate stress responses. Their impact on other cellular regulators is emerging. Inappropriately elevated protein levels of the MDM family are highly associated with an increased risk of cancer incidence. Exploration of the MDM family members as cancer therapeutic targets is relevant for designing tailored anti-cancer treatments, but successful approaches must strategically consider the impact on both the target cancer and adjacent healthy cells and tissues. This review focuses on recent findings pertaining to the role of the MDM family in normal and malignant breast cells.
- Julia P. Cooper (Telomere Biology Center for Cancer Research Bethesda USA),
- Daniel Durocher (DNA Damage The Lunenfeld-Tanenbaum Research Institute Toronto Ontario Canada),
- Marcos Malumbres (CNIO Spain)
- Antoine van Oijen (Single-molecule biophysics, DNA replication, School of Chemistry, University of Wollongong NSW Australia).
- ‘+’ lots more
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8th Garvan Signalling Symposium
We welcome scientists at all levels, including students, post-docs, research staff and senior lab heads. The intimate nature of the meeting and enjoyable social functions promotes a collegial atmosphere and excellent networking opportunities. A poster session will be held on the Monday afternoon with generous prizes. Slots have been reserved for short (15 minutes) talks to be selected from submitted abstracts.
The meeting is held at the Garvan Institute in the glamorous Darlinghurst region of Sydney, close to the city, Oxford Street, King’s Cross and the harbour.
This years exciting program features state-of-the-art technologies to investigate a wide range of diseases including cancer, immunology, neuroscience and metabolic disorders. Special sessions focus on in vivo/intravital signalling, proteomics, control of gene regulation and the structural basis of signalling.
Click Here for more information and to register