Biology subjects

Vizeacoumar, F.

Publications and source records attributed to Vizeacoumar, F..

4 recordsLinked to original sources

bioRxiv2024

A novel role for Neurog2 in MYCN driven neuroendocrine plasticity of prostate cancer

Neuroendocrine prostate cancer (NEPC) presents a formidable clinical challenge owing to its aggressive progression and resistance to conventional therapies. A key driver of NEPC is the overexpression of MYCN, a well-established oncogene associated with neuroendocrine tumors. However, efforts to directly inhibit the N-Myc protein encoded by this gene have resulted in limited success, thereby hindering therapeutic advancements. To overcome this obstacle, we conducted unbiased genome-wide screening using isogenic prostate cancer cell lines to identify the synthetic vulnerabilities of MYCN. Among the identified candidates, NEUROG2 emerged as a significant candidate. Neurog2 is a proneural transcription factor (PTF) known for its role in developmental processes and trans-differentiation of adult cells. Our findings demonstrate that Neurog2 depletion does not affect non-malignant cells, but significantly suppresses the growth of MYCN-overexpressing cells and tumors in orthotopic NEPC models. Furthermore, our observations indicate that the Neurog2-mediated regulation of PTFs can facilitate NEPC development. Thus, targeting Neurog2 holds promise as an effective therapeutic strategy for MYCN-overexpressing NEPC.

cancer biology↗

bioRxiv2023

Generation of a SARS-CoV-2 reverse genetics system and novel human lung cell lines that exhibit high virus-induced cytopathology

The global COVID-19 pandemic continues with an increasing number of cases worldwide and the emergence of new SARS-CoV-2 variants. In our study, we have developed novel tools with applications for screening antivirals, identifying virus-host dependencies, and characterizing viral variants. Using reverse genetics, we rescued SARS-CoV-2 Wuhan1 (D614G variant) wild type (WTFL) and reporter virus (NLucFL) using molecular BAC clones. The replication kinetics, plaque morphology and titers were comparable between rescued molecular clones and a clinical isolate (VIDO-01 strain), thus providing confidence that the rescued viruses can be used as effective replication tools. Furthermore, the reporter SARS-CoV-2 NLucFL virus exhibited robust luciferase values over the time course of infection and was used to develop a rapid antiviral assay using remdesivir as proof-of-principle. In addition, as a tool to study lung-relevant virus-host interactions, we established novel human lung cell lines that support SARS-CoV-2 infection with high virus-induced cytopathology. Six lung cell lines (NCI-H23, A549, NCI-H1703, NCI-H520, NCI-H226, and HCC827) and HEK293T cells, were transduced to stably express ACE2 and tested for their ability to support virus infection. A549ACE2 B1 and HEK293TACE2 A2 cell lines exhibited more than 70% virus-induced cell death and a novel lung cell line NCI-H23ACE2 A3 showed about [~]99% cell death post-infection. These cell lines are ideal for assays relying on live-dead selection and are currently being used in CRISPR knockout and activation screens in our lab. ImportanceWe used a reverse genetics system to generate a wild type as well as a nanoluciferase-expressing reporter clone of SARS-CoV-2. The reporter virus allows for rapid transient replication assays and high throughput screens by detection of virus replication using luciferase assays. In addition, the reverse genetic system can be used to generate mutant viruses to study phenotypes of variant mutations. Additionally, unique human lung cell lines supporting SARS-CoV-2 replication will aid in studying the virus in a lung-relevant environment and based on high cytopathology induced in some cell lines, will be useful for screens that rely on virus-induced cell death for selection. Our study aims to enhance and contribute to the current replication tools available to study SARS-CoV-2 by providing rapid methods, virus clones and novel lung cell lines.

molecular biology↗

bioRxiv2023

MEMO1 is a Metal Containing Regulator of Iron Homeostasis in Cancer Cells

Mediator of ERBB2-driven Cell Motility 1 (MEMO1) is an evolutionary conserved protein implicated in many biological processes; however, its primary molecular function remains unknown. Importantly, MEMO1 is overexpressed in many types of cancer and was shown to modulate breast cancer metastasis through altered cell motility. To better understand the function of MEMO1 in cancer cells, we analyzed genetic interactions of MEMO1 using gene essentiality data from 1028 cancer cell lines and found multiple iron-related genes exhibiting genetic relationships with MEMO1. We experimentally confirmed several interactions between MEMO1 and iron-related proteins in living cells or in vitro, most notably, the iron transporters transferrin (TF), transferrin receptor 2 (TFR2), and mitoferrin-2 (SLC25A28), and the global iron response regulator IRP1 (ACO1). These interactions indicate that cells with high MEMO1 expression levels are hypersensitive to the disruptions in iron distribution. Our data also indicate that MEMO1 is involved in ferroptosis and is linked to iron supply to mitochondria. We have found that purified MEMO1 binds iron with high affinity under redox conditions mimicking intracellular environment and solved MEMO1 structures in complex with iron and copper. Our work reveals that the iron coordination mode in MEMO1 is very similar to that of iron-containing extradiol dioxygenases, which also display a similar structural fold. We conclude that MEMO1 is an iron-binding protein that regulates iron homeostasis in cancer cells.

biochemistry↗

bioRxiv2020

Anaphase Promoting Complex activity mediates clinical responsiveness to recurrent caninelymphoma

Like humans, canines spontaneously develop lymphomas that are treated by chemotherapy cocktails and frequently develop multiple drug resistance (MDR). Their shortened clinical timelines and tumor accessibility make them excellent models to study MDR mechanisms. We previously demonstrated that adjunct treatment of in vitro MDR cell lines with insulin-sensitizers effectively restored MDR chemosensitivity and prevented MDR development. This study extends the use of an insulin-sensitizer to clinical and tumor responses in vivo in volunteer canines with MDR lymphoma, including assessing changes in MDR protein biomarkers and global gene expression. Longitudinal tumor sampling and analysis of MDR cases throughout treatment allowed a correlation between in vivo molecular mechanisms and clinical responsiveness. We found reduced MDR biomarkers within all tumors, yet only one canine entered clinical remission. Analysis of tumor samples during remission and relapse allowed comparison of gene expression profiles. This revealed the Anaphase Promoting Complex (APC), a ubiquitin-E3 ligase regulating cell cycle progression, was impaired during chemoresistance/MDR and restored during remission. Validating in vitro tests restored MDR chemosensitivity upon APC activation, supporting the idea that APC activity is an important underlying cellular mechanism associated with treatment resistance, and a novel potential therapeutic target.

cancer biology↗