Biology subjects

Bernards, R. R.

Publications and source records attributed to Bernards, R. R..

6 recordsLinked to original sources

bioRxiv2025

PEBP1 is a candidate biomarker of response to the PP2A inhibitor LB-100

We recently proposed an approach for cancer therapy involving a "paradoxical" activation of oncogenic signaling combined with the inhibition of stress responses. However, as with any other treatment, resistance can also emerge with hyperactivation therapy. In this study, we explored how cancer cells can acquire resistance to a drug that hyperactivates oncogenic signaling using the Protein Phosphatase 2A (PP2A) LB-100 as an example. Our findings indicated that PEBP1 depletion confers resistance to LB-100 in different cancer models. Mechanistically, resistance is mediated by a reduced conversion of the prodrug LB-100 into the active metabolite endothall in the absence of PEBP1. Our data are compatible with a model in which PEBP1 is a hydrolase that can convert the prodrug LB-100 into the active endothall.

cancer biology↗

bioRxiv2024

An antibiotic that mediates immune destruction of senescent cancer cells

Drugs that eliminate senescent cells, senolytics, can be powerful when combined with pro-senescence cancer therapies. Using a CRISPR/Cas9-based genetic screen, we identify here SLC25A23 as a vulnerability of senescent cancer cells. Suppressing SLC25A23 disrupts cellular calcium homeostasis, impairs oxidative phosphorylation and interferes with redox signaling, leading to death of senescent cells. These effects can be replicated by salinomycin, a cation ionophore antibiotic. Salinomycin prompts a PANoptosis-like cell death in senescent cells, including apoptosis and two forms of immunogenic cell death: necroptosis and pyroptosis. Notably, we observed that salinomycin treatment or SLC25A23 suppression elevates reactive oxygen species, upregulating death receptor 5 via JNK pathway activation. We show that a combination of a DR5 agonistic antibody and salinomycin is a robust senolytic cocktail. We provide evidence that this drug combination provokes a potent NK and CD8+ T cell mediated immune destruction of senescent cancer cells, mediated by the pyroptotic cytokine IL18. SignificanceThe efficacy of multiple cancer drugs is limited by the induction of senescence, which enables cancer cells to evade cell death. We uncover here a new selective vulnerability of senescent cancer cells and we show that this vulnerability can be targeted with a commonly-used antibiotic. We show that a combination of senescence-inducing therapy, combined with this antibiotic causes a highly immunogenic cell death phenotype that further stimulates potent immune destruction of senescent cancer cells.

cancer biology↗

bioRxiv2023

Somatic mutation of Afadin leads to anchorage independent survival and metastatic growth of breast cancer through alpha E-catenin dependent destabilization of the adherens junction

Loss of E-cadherin (CDH1) and the adherens junction (AJ) drive development and progression of invasive lobular breast cancer (ILC). However, approximately 40% retain wild type CDH1 alleles, indicating that modulation of other genes attenuates the AJ during ILC etiology. To identify alternative drivers, we performed targeted sequencing in CDH1 wild type samples, based on a defined set of 100 AJ, tight junction, and desmosome genes we designated as the Adhesome. In 146 ILC samples, we identified 62 cases (43%) with wild type CDH1 alleles in which we detected a total of 284 mutations in 36 Adhesome genes. After selection based on occurrence and potential loss of function, we identified an inactivating frameshift mutation in Afadin (AFDN; p.Lys630fs). Functional studies in E-cadherin-expressing breast cancer cells showed that Afadin knockout leads to immature AJs, and a non-cohesive phenotype accompanied by actomyosin dependent anoikis resistance, which are classical ILC hallmarks. Afadin reconstitutions show that F-actin organization critically depends on the E-catenin binding CC domain. Afadin loss in intraductal xenograft mouse breast cancer models leads to ILC-type morphologies and overt lung metastases. AFDN truncate reconstitutions revealed that deletion of the C-terminal E-catenin binding CC domain is sufficient to drive metastatic ILC. In conclusion, we identified and functionally coupled a somatic frameshift AFDN mutation in breast cancer to destabilization the epithelial AJ and the development of ILC hallmarks such as actomyosin-dependent anoikis resistance and single cell invasion. As such, Afadin represents a candidate tumor suppressor for E-cadherin-positive ILC development and progression.

cancer biology↗

bioRxiv2020

Identifying selective drug combinations using Comparative Network Reconstruction

Inhibition of aberrant signaling with target inhibitors is an important treatment strategy in cancer, but unfortunately responses are often short-lived. Multi-drug combinations have the potential to mitigate this, but to avoid toxicity such combinations must be selective and the dosage of the individual drugs should be as low as possible. Since the search space of multi-drug combinations is enormous, an efficient approach to identify the most promising drug combinations and dosages is needed. Here, we present a pipeline to prioritize promising multi-drug combinations. We performed a limited set of drug perturbations in an isogenic cell line pair with and without an activating PI3K mutation, and recorded their signaling states and cell viability. We used these data to reconstruct mutant specific signaling networks and map the short term signaling response to longer term changes in cell viability. The resulting models then allowed us to predict the effect of unseen multi-drug combinations, at arbitrary drug-concentrations, on cell viability. Our initial aim was to find combinations that selectively reduce the viability of the PI3K mutant cells, but our models indicated that such combinations do not exist for this cell line pair. However, we were able to validate 25 of the 30 low-dose multi-drug combinations that we predicted to be anti-selective. Our pipeline thus enables a powerful strategy to rapidly map the efficacy and possible selectivity of drug combinations, hence significantly speeding up the pace at which we can explore the vast space of combination therapies.

systems biology↗

bioRxiv2018

phospho-ERK is a response biomarker to a combination of sorafenib and MEK inhibition in liver cancer

Treatment of liver cancer remains challenging, due to a paucity of drugs that target critical dependencies. Sorafenib is a multikinase inhibitor that is approved as the standard therapy for advanced hepatocellular carcinoma patients, but it can only provide limited survival benefit for patients. To investigate the cause of this limited therapeutic effect, we performed a CRISPR-Cas9 based synthetic lethality screen to search for kinases whose knockout synergize with sorafenib. We find that suppression of ERK2 sensitizes several liver cancer cell lines to sorafenib. Drugs inhibiting the MEK or ERK kinases reverse unresponsiveness to sorafenib in vitro and in vivo in a subset of liver cancer cell lines characterized by high levels of active phospho-ERK levels through synergistic inhibition of ERK kinase activity. Our data provide a combination strategy for treating liver cancer and suggest that tumors with activation of p-ERK, which is seen in some 30% of liver cancers, are most likely to benefit from such combinatorial treatment.

cancer biology↗

bioRxiv2017

A system-wide approach to monitor responses to synergistic BRAF and EGFR inhibition in colorectal cancer cells

Intrinsic and/or acquired resistance represents one of the great challenges in targeted cancer therapy. A deeper understanding of the molecular biology of cancer has resulted in more efficient strategies, where one or multiple drugs are adopted in novel therapies to tackle resistance. This beneficial effect of using combination treatments has also been observed in colorectal cancer patients harboring the BRAF(V600E) mutation, whereby dual inhibition of BRAF(V600E) and EGFR increases antitumor activity. Notwithstanding this success, it is not clear whether this combination treatment is the only or most effective treatment to block intrinsic resistance to BRAF inhibitors. Here, we investigate molecular responses upon single and multi-target treatments, over time, using BRAF(V600E) mutant colorectal cancer cells as a model system. Through integration of transcriptomic, proteomic and phosphoproteomics data we obtain a comprehensive overview, revealing both known and novel responses. We primarily observe widespread upregulation of receptors tyrosine kinases and metabolic pathways upon BRAF inhibition. These findings point to mechanisms by which the drug-treated cells switch energy sources and enter a quiescent-like state as a defensive response, while additionally reactivating the MAPK pathway.

cancer biology↗