Biology subjects

Passos, D.

Publications and source records attributed to Passos, D..

5 recordsLinked to original sources

bioRxiv2026

WNT8B and -9B promote the survival and dissemination of dormant ovarian cancer cells

Cancer cell dormancy and the resultant resistance to conventional therapies present significant challenges for the successful treatment of high-grade serous ovarian cancer (HGSC). We used genome wide, and specialized sgRNA, libraries in CRISPR-based screens to identify critical cell survival mechanisms in dormancy and metastasis. Our findings demonstrate that low expression Wnt ligands WNT8B and WNT9B are essential for sustaining cell survival during prolonged dormant spheroid culture conditions. These Wnt ligands utilize non-canonical signaling to activate expression of stem cell genes such as ALDH1A1, CD44 and others during spheroid dormancy. The loss of WNT8B and WNT9B reduced survival of xenografted ovarian cancer cells during early dissemination of disease that extended survival. Furthermore, treatment of WNT8B/9B deficient xenografts with carboplatin demonstrated increased sensitivity that further reduced dissemination and extended survival. These findings reveal that rare Wnt ligands can possess outsized functions in cancer pathogenesis and offer new avenues for improving treatment outcomes for HGSC through their inhibition.

cancer biology↗

bioRxiv2024

Oligomeric HIV-1 Integrase Structures Reveal Functional Plasticity for Intasome Assembly and RNA Binding

Integrase (IN) performs dual essential roles during HIV-1 replication. During ingress, IN functions within an oligomeric "intasome" assembly to catalyze viral DNA integration into host chromatin. During late stages of infection, tetrameric IN binds viral RNA and orchestrates the condensation of ribonucleoprotein complexes into the capsid core. The molecular architectures of HIV-1 IN assemblies that mediate these distinct events remain unknown. Furthermore, the tetramer is an important antiviral target for allosteric IN inhibitors. Here, we determined cryo-EM structures of wildtype HIV-1 IN tetramers and intasome hexadecamers. Our structures unveil a remarkable plasticity that leverages IN C-terminal domains and abutting linkers to assemble functionally distinct oligomeric forms. Alteration of a newly recognized conserved interface revealed that both IN functions track with tetramerization in vitro and during HIV-1 infection. Collectively, our findings reveal how IN plasticity orchestrates its diverse molecular functions, suggest a working model for IN-viral RNA binding, and provide atomic blueprints for allosteric IN inhibitor development.

biochemistry↗

bioRxiv2023

Netrin signaling mediates survival of dormant epithelial ovarian cancer cells

Dormancy in cancer is a clinical state in which residual disease remains undetectable for a prolonged duration. At a cellular level, rare cancer cells cease proliferation and survive chemotherapy and disseminate disease. We created a suspension culture model of high grade serous ovarian cancer (HGSOC) dormancy and devised a novel CRISPR screening approach to identify survival genes in this context. In combination with RNA-seq, we discovered the Netrin signaling pathway as critical to dormant HGSOC cell survival. We demonstrate that Netrin-1, -3, and its receptors are essential for low level ERK activation to promote survival, and that Netrin activation of ERK is unable to induce proliferation. Deletion of all UNC5 family receptors blocks Netrin signaling in HGSOC cells and compromises viability during the dormancy step of dissemination in xenograft assays. Furthermore, we demonstrate that Netrin-1 and -3 overexpression in HGSOC correlates with poor outcome. Specifically, our experiments reveal that Netrin overexpression elevates cell survival in dormant culture conditions and contributes to greater spread of disease in a xenograft model of abdominal dissemination. This study highlights Netrin signaling as a key mediator HGSOC cancer cell dormancy and metastasis.

cancer biology↗

bioRxiv2022

Mechanisms of HIV-1 Integrase Resistance to Dolutegravir and Potent Inhibition of Drug Resistant Variants

HIV-1 infection depends on the integration of viral DNA into host chromatin. Integration is mediated by the viral enzyme integrase and is blocked by integrase strand transfer inhibitors (INSTIs), first-line antiretroviral therapeutics widely used in the clinic. Resistance to even the best INSTIs is a problem and the mechanisms of resistance are poorly understood. Here, we analyze combinations of the mutations E138K, G140A/S, and Q148H/K/R, which confer resistance to INSTIs. The investigational drug 4d more effectively inhibited the mutants compared with the approved drug Dolutegravir (DTG). We present 11 new cryo-EM structures of drug resistant HIV-1 intasomes bound to DTG or 4d, with better than 3 [A] resolution. These structures, complemented with free energy simulations, virology, and enzymology, explain the mechanisms of DTG resistance involving E138K+G140A/S+Q148H/K/R and show why 4d maintains potency better than DTG. These data establish a foundation for further development of INSTIs that potently inhibit resistant forms in integrase.

biophysics↗

bioRxiv2018

Context dependent roles for RB-E2F transcriptional regulation in tumor suppression

RB-E2F transcriptional control plays a key role in regulating the timing of cell cycle progression from G1 to S-phase in response to growth factor stimulation. Despite this role, it is genetically dispensable for cell cycle exit in primary fibroblasts in response to growth arrest signals. Mice engineered to be defective for RB-E2F transcriptional control at cell cycle genes were also found to live a full lifespan with no susceptibility to cancer. Based on this background we sought to probe the vulnerabilities of RB-E2F transcriptional control defects found in Rb1R461E,K542E mutant mice (Rb1G) through genetic crosses with other mouse strains. We generated Rb1G/G mice in combination with Trp53 and Cdkn1a deficiencies, as well as in combination with KrasG12D. The Rb1G mutation enhanced Trp53 cancer susceptibility, but had no effect in combination with Cdkn1a deficiency or KrasG12D. Collectively, this study indicates that compromised RB-E2F transcriptional control is not uniformly cancer enabling, but rather has potent oncogenic effects when combined with specific vulnerabilities.

cancer biology↗