Biology subjects

Przanowska, R. K.

Publications and source records attributed to Przanowska, R. K..

8 recordsLinked to original sources

bioRxiv2026

IL-6R blockade with tocilizumab disrupts pericyte-and tumor cell-driven IL-6/STAT3 signaling, enhancing docetaxel efficacy in ER+ breast cancer

Metastatic breast cancer is a global health concern with a persistently low five-year survival rate. Taxane microtubule stabilizers, including docetaxel (DTX), are the standard of care in various treatment protocols. DTX is used both as a single agent and in combination therapies, with a majority of ER+ breast cancer patients ultimately developing chemoresistance. The mechanisms contributing to chemoresistance involving the tumor microenvironment (TME) have not been fully elucidated. Specifically, the role of vascular cells within the TME, particularly pericytes, is understudied, and their role in promoting chemoresistance remains unknown. Inflammatory cytokines such as interleukin 6 (IL-6) are known to drive drug resistance via activation of the pro-survival JAK/STAT pathway. We found that DTX induced IL-6 secretion of pericytes by at least two-fold compared to vehicle-treated controls in vitro. All tested breast cancer cell lines expressed subunits of the IL-6 receptor (IL-6R) complex, indicating their capacity to respond to JAK/STAT signaling. Conditioned media from DTX-treated pericytes activated STAT3 in ER+ breast cancer cells to levels comparable to recombinant IL-6. Pharmacologic blockade of IL-6 signaling with the IL-6R inhibitor, tocilizumab, reduced DTX-induced STAT3 activation in vitro. Furthermore, combined treatment with tocilizumab and DTX synergistically suppressed the growth of zero-passage patient-derived ER+ breast cancer organoids expressing intact IL-6 signaling. Together, our findings suggest that combining DTX with tocilizumab may revert DTX-induced chemoresistance in ER+ breast cancer patients by inhibiting IL-6-mediated activation of the STAT3 pathway.

cancer biology↗

bioRxiv2025

Fast, flexible, learning-free organoid quantification and tracking with OrganoSeg2

Organoids are routinely imaged by brightfield microscopy at low magnification, but these images are challenging to analyze quantitatively at scale. Given differences in organoid-culture format and image acquisition among research groups, there is a general need for versatile segmentation algorithms that refine for specific applications. Here, we introduce OrganoSeg2, an overhauled software that substantively advances the multi-window adaptive thresholding of its predecessor. OrganoSeg2 gives users access to additional segmentation parameters that were latent in OrganoSeg, and common operations are accelerated [~]10-fold. Using data from six organoid types, we find that the generalized segmentation accuracy of OrganoSeg2 surpasses multiple alternatives, including segmenters based on deep learning. OrganoSeg2 adds longitudinal single-organoid tracking and multicolor fluorescence quantification, which we use to examine growth trajectories and radiotherapy responses in luminal breast cancer organoids. OrganoSeg2 is shared freely as installation packages for current users and source code for future developers (https://github.com/JanesLab/OrganoSeg2). MOTIVATIONOrganoids are routinely documented with low-magnification brightfield and fluorescence images that are challenging to quantify accurately in large numbers. OrganoSeg2 is a streamlined, highly customizable segmenter that surpasses its prior version and AI-themed competitors in various organoid contexts. New longitudinal tracking and fluorescence capabilities of OrganoSeg2 are demonstrated with experiments investigating the cell-death responses of luminal breast cancer organoids to radiotherapy.

bioengineering↗

bioRxiv2024

A 36-base hairpin within lncRNA DRAIC, which is modulated by alternative splicing, interacts with the IKKα coiled-coil domain and inhibits NF-kB and tumor cell phenotypes

A tumor-suppressive long noncoding RNA (lncRNA) DRAIC (down-regulated RNA in cancers) inhibits NF-{kappa}B activity and physically interacts with IKK, a kinase component of the IKK complex, in several cancer types. Here we explore the precise molecular mechanism involved in this interaction and suppression. Using SHAPE-MaP, we identified a 36-nucleotide hairpin (A+B) within DRAIC that is necessary and sufficient for its anti-oncogenic function. RNA immunoprecipitation (RIP) and Electrophoretic mobility shift assays (EMSA) confirmed this hairpin physically interacts with the coiled coil domain of IKK. A+B RNA has a high binding affinity (KD [~]1-7 nM) to the coiled-coil domain of IKK. The binding of A+B disrupts the dimerization of NEMO and IKK coiled-coil domains, a critical step for IKK action. Consistent with this, A+B inhibits the phosphorylation of the NF-{kappa}B inhibitor I{kappa}B and suppresses NF-{kappa}B activity. Publicly available tumor RNAseq data revealed that alternative splicing modulates the presence of this critical hairpin: the inclusion of exon 4a (encoding one side of the A+B hairpin) in lung tumors correlates with reduced NF-{kappa}B activity. By demonstrating that the A+B hairpin is both necessary and sufficient to inhibit IKK and oncogenic phenotypes, this study underscores the centrality of IKK interaction and NF-{kappa}B inhibition in DRAIC-mediated cancer suppression and indicates that the activity of this lncRNA is regulated by alternative splicing. This study also reveals the first example of a short RNA disrupting coiled-coil dimerization, offering a new approach to disrupt such dimerization in cancer biology.

molecular biology↗

bioRxiv2024

Endo-reduplication in mouse liver after conditional mutation of ORC2 and combined mutation of ORC1 and ORC2

The six subunit ORC is essential for initiation of DNA replication in eukaryotes. Cancer cell-lines in culture can survive and replicate DNA replication after genetic inactivation of individual ORC subunits, ORC1, ORC2 or ORC5. In primary cells, ORC1 was dispensable in the mouse liver for endo-reduplication, but this could be explained by the ORC1 homolog, CDC6, substituting for ORC1 to restore functional ORC. Here, we have created mice with a conditional deletion of ORC2, which does not have a homolog. Although mouse embryo fibroblasts require ORC2 for proliferation, mouse hepatocytes synthesize DNA in cell culture and endo-reduplicate in vivo without ORC2. Mouse livers endo-reduplicate after simultaneous deletion of ORC1 and ORC2 both during normal development and after partial hepatectomy. Since endo-reduplication initiates DNA synthesis like normal S phase replication these results unequivocally indicate that primary cells, like cancer cell lines, can load MCM2-7 and initiate replication without ORC.

genetics↗

bioRxiv2021

ANKLE1 cleaves mitochondrial DNA and contributes to cancer risk by driving the Warburg effect and apoptosis resistance

Alleles within the chr19p13.1 locus are associated with increased risk of both ovarian and breast cancer and increased expression of the ANKLE1 gene. ANKLE1 is molecularly characterized as an endonuclease that efficiently cuts branched DNA and shuttles between the nucleus and cytoplasm. However, the role of ANKLE1 in mammalian development and homeostasis remains unknown. In normal development ANKLE1 expression is limited to the erythroblast lineage and we found that ANKLE1s role is to cleave the mitochondrial genome during erythropoiesis. We show that ectopic expression of ANKLE1 in breast epithelial-derived cells leads to genome instability and mitochondrial DNA (mtDNA) cleavage. mtDNA degradation then leads to mitophagy and causes a shift from oxidative phosphorylation to glycolysis (Warburg effect). Moreover, mtDNA degradation activates STAT1 and expression of epithelial-mesenchymal transition (EMT) genes. Reduction in mitochondrial content contributes to apoptosis resistance, which may allow precancerous cells to avoid apoptotic checkpoints and proliferate. These findings provide evidence that ANKLE1 is the causal cancer susceptibility gene in the chr19p13.1 locus and describe mechanisms by which higher ANKLE1 expression promotes cancer risk.

cancer biology↗

bioRxiv2021

Distinct MUNC lncRNA structural domains regulate transcription of different promyogenic factors

Many lncRNAs have been discovered using transcriptomic data, however, it is broadly unclear what fraction of lncRNAs are functional and what structural properties affect their phenotype. MUNC lncRNA, also known as DRReRNA, stimulates skeletal muscle differentiation. The prevailing hypothesis is that MUNC stimulates the Myod1 gene in cis as an enhancer RNA and stimulates expression of several other promyogenic genes in trans by recruiting the cohesin complex to their promoters. Experimental probing of the RNA structure revealed that MUNC contains multiple structural domains not detected by RNA structure prediction algorithms in the absence of experimental information. We discovered that these specific and structurally distinct domains are required for induction of different promyogenic genes, for binding at different genomic sites to regulate the expression of adjacent genes, and for binding the cohesin complex. Moreover, we found that induction of Myod1 or interaction with cohesin comprise only a subset of the broad regulatory impact of this lncRNA. Our study thus reveals unexpectedly complex, structure-driven functions for the MUNC lncRNA and emphasizes the importance of experimentally determined structures for understanding structure-function relationships in lncRNAs.

molecular biology↗

bioRxiv2019

tRNA-derived fragments and microRNAs in the maternal-fetal interface of a mouse maternal-immune-activation autism model

tRNA-derived small fragments (tRFs) and tRNA halves have emerging functions in different biological pathways, such as regulating gene expression, protein translation, retrotransposon activity, transgenerational epigenetic changes and response to environmental stress. However, small RNAs like tRFs and microRNAs in the maternal-fetal interface during gestation have not been studied extensively. Here we investigated the small RNA composition of mouse placenta/decidua, which represents the interface where the mother communicates with the fetus, to determine whether there are specific differences in tRFs and microRNAs during fetal development and in response to maternal immune activation (MIA). Global tRF expression pattern, just like microRNAs, can distinguish tissue types among placenta/decidua, fetal brain and fetal liver. In particular, 5 tRNA halves from tRNAGly, tRNAGlu, tRNAVal and tRNALys are abundantly expressed in the normal mouse placenta/decidua. Moreover, tRF and microRNA levels in the maternal-fetal-interface change dynamically over the course of embryonic development. To see if stress alters non-coding RNA expression at the maternal-fetal interface, we treated pregnant mice with a viral infection mimetic, which has been shown to promote autism-related phenotypes in the offspring. Acute changes in the levels of specific tRFs and microRNAs were observed 3-6 hours after MIA and are suppressed thereafter. A group of 5 tRNA halves is down-regulated by MIA, whereas a group of 18-nucleotide tRF-3a is up-regulated. In conclusion, tRFs show tissue-specificity, developmental changes and acute response to environmental stress, opening the possibility of them having a role in the fetal response to MIA.

molecular biology↗

bioRxiv2019

miR-206 family is important for mitochondrial and muscle function, but not essential for myogenesis in vitro

miR-206, miR-1a-1 and miR-1a-2 are induced during differentiation of skeletal myoblasts and promote myogenesis in vitro. miR-206 is required for skeletal muscle regeneration in vivo. Although this microRNA family is hypothesized to play an essential role in differentiation, a triple knockout of the three genes has not been done to test this hypothesis. We report that triple KO C2C12 myoblasts generated using CRISPR/Cas9 method differentiate despite the expected de-repression of the microRNA targets. Surprisingly, their mitochondrial function is diminished. Triple KO mice demonstrate partial embryonic lethality, most likely due to the role of miR-1a in cardiac muscle differentiation. Two triple KO mice survive and grow normally to adulthood with smaller myofiber diameter and diminished physical performance. Thus, unlike other microRNAs important in other differentiation pathways, the miR-206 family is not absolutely essential for myogenesis and is instead a modulator of optimal differentiation of skeletal myoblasts.

molecular biology↗