Biology subjects

Hulea, L.

Publications and source records attributed to Hulea, L..

5 recordsLinked to original sources

bioRxiv2026

eIF4A inhibition disrupts resistance-associated translational and metabolic programs in BRAF-mutant melanoma

Acquired resistance to mitogen-activated protein kinase (MAPK) pathway inhibitors remains a major barrier to durable control of BRAF-mutant melanoma. Although resistance mechanisms are heterogeneous, they converge on adaptive programs that support survival, phenotypic plasticity, and metabolic fitness. We asked whether eukaryotic translation initiation factor 4A (eIF4A)-dependent mRNA translation represents a shared vulnerability of kinase inhibitor-resistant melanoma. Using matched BRAFV600E A375 and BRAF inhibitor-resistant A375R cells together with additional melanoma models, we integrated pharmacological and functional assays with polysome-associated RNA sequencing, quantitative proteomics, bioenergetic profiling, metabolomics, [U-13C5]glutamine tracing, and xenograft studies. Melanoma cells remained sensitive to multiple eIF4A inhibitors regardless of their responsiveness to BRAF inhibition. The eIF4A inhibitor CR-1-31-B rapidly reduced nascent protein synthesis when used alone in A375 cells and when added to the BRAF inhibitor PLX4032 in A375R cells; it also reduced BCL-2, CDK4, and cyclin D3 abundance, suppressed clonogenic growth, and induced apoptosis. Integrated analysis showed that acquired resistance involved broad RNA-abundance remodeling with superimposed changes in translational efficiency and buffering, affecting survival, extracellular-matrix and plasticity programs, and mitochondrial and metabolic functions. In resistant cells, CR-1-31-B induced early transcript-selective translational changes, accompanied at later time points by RNA-abundance and proteome remodeling. Publicly annotated 5' untranslated regions (5'UTRs) of CR-1-31-B-sensitive transcripts were enriched for purine-rich sequence architecture and local structural complexity. eIF4A inhibition preferentially attenuated the expression of proteins acquired during resistance and imposed a lower-output metabolic state in sensitive and resistant cells, reducing tricarboxylic-acid-cycle and pentose-phosphate-pathway metabolite pools and restricting intracellular glutamine-carbon transfer downstream of uptake. In A375 xenografts, CR-1-31-B delayed tumor growth, while its combination with PLX4720 produced deeper and more sustained tumor control and prolonged tumor endpoint-free survival compared with PLX4720 alone. These findings show that multiple resistance-associated programs spanning signaling, cell survival, and metabolism share a dependency on eIF4A-dependent translation and provide a preclinical rationale to test whether adding eIF4A inhibition can prolong responses to MAPK-targeted therapy in melanoma.

cancer biology↗

bioRxiv2024

O-GlcNAcylation of FOXK1 orchestrates the E2F pathway and promotes oncogenesis

Gene transcription is a highly regulated process, and deregulation of transcription factors activity underlies numerous pathologies including cancer. Albeit near four decades of studies have established that the E2F pathway is a core transcriptional network that govern cell division in multi-cellular organisms1,2, the molecular mechanisms that underlie the functions of E2F transcription factors remain incompletely understood. FOXK1 and FOXK2 transcription factors have recently emerged as important regulators of cell metabolism, autophagy and cell differentiation3-6. While both FOXK1 and FOXK2 interact with the histone H2AK119ub deubiquitinase BAP1 and possess many overlapping functions in normal biology, their specific functions as well as deregulation of their transcriptional activity in cancer is less clear and sometimes contradictory7-13. Here, we show that elevated expression of FOXK1, but not FOXK2, in primary normal cells promotes transcription of E2F target genes associated with increased proliferation and delayed entry into cellular senescence. FOXK1 expressing cells are highly prone to cellular transformation revealing important oncogenic properties of FOXK1 in tumor initiation. High expression of FOXK1 in patient tumors is also highly correlated with E2F gene expression. Mechanistically, we demonstrate that FOXK1, but not FOXK2, is specifically modified by O-GlcNAcylation. FOXK1 O-GlcNAcylation is modulated during the cell cycle with the highest levels occurring during the time of E2F pathway activation at G1/S. Moreover, loss of FOXK1 O-GlcNAcylation impairs FOXK1 ability to promote cell proliferation, cellular transformation and tumor growth. Mechanistically, expression of FOXK1 O-GlcNAcylation-defective mutants results in reduced recruitment of BAP1 to gene regulatory regions. This event is associated with a concomitant increase in the levels of histone H2AK119ub and a decrease in the levels of H3K4me1, resulting in a transcriptional repressive chromatin environment. Our results define an essential role of O-GlcNAcylation in modulating the functions of FOXK1 in controlling the cell cycle of normal and cancer cells through orchestration of the E2F pathway.

molecular biology↗

bioRxiv2023

Flaviviruses alter endoplasmic reticulum-mitochondria contacts to regulate respiration and apoptosis

With no therapeutics available, there is an urgent need to better understand the pathogenesis of flaviviruses which constitute a threat to public health worldwide. During infection, dengue virus (DENV) and Zika virus (ZIKV), two flaviviruses induce alterations of mitochondria morphology to favor viral replication, suggesting a viral co-opting of mitochondria functions. Here, we performed an extensive transmission electron microscopy-based quantitative analysis to demonstrate that both DENV and ZIKV alter endoplasmic reticulum-mitochondria contacts (ERMC). This correlated at the molecular level with an impairment of ERMC tethering protein complexes located at the surface of both organelles. Furthermore, virus infection, as well as NS4B expression modulated the mitochondrial oxygen consumption rate. Consistently, metabolomic and mitoproteomic analyses revealed a decrease in the abundance of several metabolites of the Krebs cycle and changes in the stoichiometry of the electron transport chain. Most importantly, ERMC destabilization by protein knockdown increased virus replication while dampening ZIKV-induced apoptosis. Overall, our results support the notion that flaviviruses hijack ERMCs to generate a cytoplasmic environment beneficial for sustained and efficient replication.

microbiology↗

bioRxiv2022

CBFA2T3-GLIS2-dependent pediatric acute megakaryoblastic leukemia is driven by GLIS2 and sensitive to Navitoclax

Pediatric acute megakaryoblastic leukemia (AMKL) is an aggressive, uncurable blood cancer associated with poor therapeutic response and high mortality. We developed CBFA2T3-GLIS2-driven mouse models of AMKL that recapitulate the phenotypic and transcriptional signatures of the human disease. We show that an activating Ras mutation, which occurs in human AMKL, increased the penetrance and decreased the latency of CBF2AT3-GLIS2-driven AMKL. CBFA2T3-GLIS2 and GLIS2 modulate similar transcriptional networks. We uncover the dominant oncogenic properties of GLIS2, which trigger AMKL in cooperation with oncogenic Ras. We find that both CBFA2T3-GLIS2 and GLIS2 alter the expression of numerous BH3-only proteins, causing AMKL cell sensitivity to the BCL-2 inhibitor navitoclax both in vitro and in vivo, suggesting a novel therapeutic option for pediatric patients suffering from CBFA2T3-GLIS2-driven AMKL. Key pointsGLIS2 cooperates with activated Nras to promote the development of acute megakaryoblastic leukemia. CBFA2T3-GLIS2 and GLIS2 alter the expression of BCL2 family members rendering AMKL cells sensitive to navitoclax.

cancer biology↗

bioRxiv2017

Translational and HIF1α-dependent metabolic reprograming underpin oncometabolomeplasticity and synergy between oncogenic kinase inhibitors and biguanides.

There is heightened interest to devise therapies that target the oncometabolome. We show that kinase inhibitors (KIs) and biguanides synergistically target melanoma, leukemia, and breast, colon and renal cancer cells, but not non-transformed cells. Metabolic profiling confirmed opposing effects of KIs and biguanides on glycolysis, but this was insufficient to explain the observed synergy between the drugs. Rather, we define a critical role for the synthesis of non-essential amino acids (NEAA) aspartate, asparagine and serine as well as reductive glutamine metabolism, in determining the sensitivity of cancer cells to KI - biguanide combinations. The mTORC1/4E-BP axis regulates aspartate, asparagine and serine synthesis by modulating translation of mRNAs encoding PC, ASNS, PHGDH and PSAT1. Ablation of 4E-BP1 and 2 results in a dramatic increase in serine, aspartate and asparagine levels and a substantial decrease in sensitivity of breast cancer and melanoma cells to KI - biguanide combinations. In turn, efficacy of KI - biguanide combinations is impeded by HIF1 and sustained reductive glutamine metabolism. These findings identify hitherto unappreciated translational reprograming of NEAA synthesis and HIF1-dependent stimulation of reductive glutamine metabolism as critical metabolic vulnerabilities of cancer that underpin synergy between KIs and biguanides.

cancer biology↗