Biology subjects

Kominek, A.

Publications and source records attributed to Kominek, A..

4 recordsLinked to original sources

bioRxiv2024

Hypoxic stress dysregulates functions of glioma-associated myeloid cells through epigenomic and transcriptional programs

Hypoxia rapidly alters gene expression to allow cellular adaptation to challenging conditions and support tumour growth. Hypoxia also affects the chromatin structure by modifications of histones and DNA methylation. Glioblastoma (GBM) is an aggressive, deadly primary brain tumour for which there is no effective treatment. The tumour microenvironment of GBM is highly heterogeneous, with infiltration of glioma-associated microglia and macrophages (GAMs) and the presence of necrotic, hypoxic regions which significantly impair effectiveness of therapies. The mechanisms through which hypoxia alters the tumour microenvironment and regulates functions of infiltrating immune cells remain poorly understood. Here, we show that hypoxia modulates the expression of myeloid markers in distinct ways: upregulates the expression of monocytic marker Lgals3 and downregulates the microglial markers P2ry12 and Tmem119 in microglial and monocytic GAMs in vitro and in vivo. Underlying genome-wide hypoxia-dependent transcriptomic changes in microglial cells were identified using microglia-glioma co-cultures and validated in human and mouse GBM single- cell transcriptomics datasets. Numerous GAM subtype markers are dysregulated in response to hypoxic stress due to associated changes in chromatin accessibility, as determined using ATACseq. While hypoxia alone drives a decrease of the overall chromatin accessibility at gene promoters, the exposure to glioma cells under hypoxic conditions leads to both increases and decreases of chromatin accessibility at promoter regions in microglial cells. Hypoxia downregulates the chromatin accessibility at the regions enriched in motifs for transcription factors known as master regulators of microglial cell identity and function, including SPI1 or IRF8. Overall, our results highlight the importance of hypoxic stress as a strong intratumoral regulator of myeloid cell functions, which adds a new dimension to the characterisation of particular GAM subpopulations.

cancer biology↗

bioRxiv2021

Targeting Integrated Stress Response by ISRIB combined with imatinib attenuates STAT5 signaling and eradicates therapy-resistant Chronic Myeloid Leukemia cells

Integrated Stress Response (ISR) facilitates cellular adaptation to variable environmental conditions by reprogramming cellular response. Activation of ISR was reported in neurological disorders and solid tumours, but its function in hematological malignancies remains largely unknown. Previously we showed that ISR is activated in chronic myeloid leukemia (CML) CD34+ cells, and its activity correlates with disease progression and imatinib resistance. Here we demonstrate that inhibition of ISR by small molecule ISRIB, but not by PERK inhibitor GSK2656157, restores sensitivity to imatinib and eliminates CM Blast Crisis (BC) D34+ resistant cells. We found that in Patient Derived Xenograft (PDX) mouse model bearing CD34+ imatinib/dasatinib-resistant CML blasts with PTPN11 gain-of-function mutation, combination of imatinib and ISRIB decreases leukemia engraftment. Furthermore, genes related to SGK3, RAS/RAF/MAPK, JAK2 and IFN{gamma} pathways were downregulated upon combined treatment. Remarkably, we confirmed that ISRIB and imatinib combination decreases STAT5 phosphorylation and inhibits expression of STAT5-target genes responsible for proliferation, viability and stress response. Thus, our data point to a substantial effect of imatinib and ISRIB combination, that results in transcriptomic deregulation and eradication of imatinib-resistant cells. Our findings suggest such drug combination might improve therapeutic outcome of TKI-resistant leukemia patients exhibiting constitutive STAT5 activation.

cancer biology↗

bioRxiv2020

Splicing variation of BMP2K balances endocytosis, COPII trafficking and autophagy in erythroid cells

Intracellular transport undergoes remodeling upon cell differentiation, which involves cell type-specific regulators. Bone morphogenetic protein 2-inducible kinase (BMP2K) has been potentially implicated in endocytosis and cell differentiation but its molecular functions remained unknown. We discovered that its longer (L) and shorter (S) splicing variants regulate erythroid differentiation in a manner unexplainable by their involvement in AP-2 adaptor phosphorylation and endocytosis. However, both variants interacted with SEC16A whose silencing in K562 erythroid leukemia cells affected generation of COPII assemblies and induced autophagic degradation. Variant-specific depletion approach showed that BMP2K isoforms constitute a BMP2K-L/S regulatory system. Therein, L promotes while S restricts recruitment of SEC31A to SEC24B-containing COPII structures forming at SEC16A-positive ER exit sites. Finally, we found L to promote and S to restrict autophagic degradation. Hence, we propose that BMP2K-L favors SEC16A-dependent intracellular processes important for erythroid maturation, such as COPII trafficking and autophagy, in a manner inhibited by BMP2K-S.

cell biology↗

bioRxiv2018

Tunneling nanotubes contribute to the stroma-mediated imatinib resistance of leukemic cells

Intercellular communication within the bone marrow niche significantly influences leukemogenesis and the sensitivity of leukemic cells to therapy. Tunneling nanotubes (TNTs) are a novel mode of intercellular cross-talk. They are long, thin membranous protrusions that enable the direct transfer of various cargo between cells. Here we show that TNTs are formed between leukemic and bone marrow stromal cells. Fluorescence confocal microscopy with 3D reconstructions, correlative light-electron microscopy and electron tomography provided evidence that TNTs transfer cellular vesicles between cells. The quantitative analysis demonstrated that the stromal cells stimulate TNT-mediated vesicle transfer towards leukemic cells. Transfer of vesicular cargo from stromal cells correlated with increased resistance to anti-leukemic treatment. Moreover, specific sets of proteins with a potential role in survival and the drug response were transferred within these vesicles. Altogether, we found that TNTs are involved in the leukemia-stroma cross-talk and the stroma-mediated cytoprotection of leukemic cells. Our findings implicate TNT connections as a possible target for therapeutic interventions within the leukemia microenvironment to attenuate stroma-conferred protection.

cancer biology↗