Biology subjects

Padzik, A.

Publications and source records attributed to Padzik, A..

6 recordsLinked to original sources

bioRxiv2023

Transcriptional landscape of DTP-DTEP transition reveals DUSP6 as a driver of HER2 inhibitor tolerance via Neuregulin/HER3 axis

The mechanisms promoting re-growth of dormant cancer cells under continuous tyrosine kinase inhibitor (TKI) therapy are poorly understood. Here we present transcriptional profiling of HER2+ breast cancer cells treated continuously with HER2 TKI (HER2i) therapy for 9 months. The data reveals specific gene regulatory programs associated with transition from dormant drug tolerant persister cells (DTPs) to proliferating DTEP (drug tolerant expanding persister) cells and eventually long-term resistance. Focusing on yet poorly understood phosphatases as determinants of therapy tolerance, expression of dual-specificity phosphatase DUSP6 was found inhibited in DTPs, but strongly induced upon re-growth of DTEPs. DUSP6 overexpression conferred apoptosis resistance whereas its pharmacological blockade prevented DTEP development under HER2i therapy. The DUSP6-driven HER2i tolerance was mediated by activation of neuregulin-HER3 axis, and consistent with the role of HER3 in widespread therapy tolerance, DUSP6 targeting also synergized with clinically used HER2i combination therapies. In vivo, pharmacological DUSP6 targeting induced synthetic lethal effect with HER2i in independent tumor models, and its genetic targeting reduced tumor growth in orthotopic brain metastasis model. Collectively this work provides first transcriptional landscape of DTP-DTEP transition under TKI therapy, and identify DUSP6 as a novel candidate therapy target to overcome widespread HER3-driven therapy resistance.

cancer biology↗

bioRxiv2022

Lamin A/C phosphorylation at serine 22 is a conserved heat shock response to regulate nuclear adaptation during stress

The heat shock (HS) response is crucial for cell survival in harmful environments. Nuclear lamin A/C, encoded by LMNA gene, has been shown to contribute towards altered gene expression during heat shock, but the underlying mechanisms are poorly understood. Here we show that reversible lamin A/C phosphorylation at Ser22 upon HS is an evolutionary conserved stress response that is triggered in concert with HSF1 activation in human and mouse cells and can also be observed in D. melanogaster in vivo. Consequently, the phosphorylation increase facilitated nucleoplasmic localization of lamin A/C and nuclear rounding in response to HS. The importance of lamin phosphorylation equilibria in HS was confirmed by lamin A/C knock-out (KO) cells that showed deformed nuclei after HS and were rescued by ectopic expression of wild-type, but not by a phosphomimetic (S22D) lamin A mutant. Furthermore, HS triggered release of lamina-associated protein 2 (Lap2) from its association with lamin A/C and concurrently its downregulation, a response that was perturbed in lamin A/C KO cells and in LMNA mutant patient fibroblasts. The abrogated Lap2 response resulted in impaired cell cycle arrest under HS and compromised survival at the recovery. Taken together, our results suggest that the altered phosphorylation stoichiometry of lamin A/C provides an evolutionary conserved mechanism to regulate lamin structure and serve nuclear adaptation and cell survival during HS.

molecular biology↗

bioRxiv2020

A feed-forward loop between SorLA and HER3 determines heregulin response and neratinib resistance

Current evidence indicates that resistance to HER2-targeted therapies is frequently associated with HER3 and active signaling via HER2-HER3 dimers, particularly in the context of breast cancer. Thus, understanding the response to HER2-HER3 signaling and the regulation of the dimer per se remains essential to decipher therapy relapse mechanisms. Here, we demonstrate that signaling by HER3 growth factor ligands, heregulins, support the transcription of a type-1 transmembrane sorting receptor, sortilin-related receptor (SorLA; SORL1) downstream of the mitogen-activated protein kinase pathway. In addition, we demonstrate that SorLA interacts directly with HER3, forming a trimeric complex with HER2 and HER3 to attenuate lysosomal degradation of the dimer through a Rab4-dependent manner. In line with a role for SorLA in supporting the stability of the HER2 and HER3 receptors, loss of SorLA compromised heregulin-induced cell proliferation and sensitized metastatic anti-HER2 therapy-resistant breast cancer cells to neratinib in cancer spheroids in vitro and in vivo in a zebrafish brain xenograft model. Collectively, our results demonstrate a novel feed-forward loop consisting of heregulin, HER2-HER3 and SorLA, which controls breast cancer growth and anti-HER2 therapy resistance in vitro and in vivo. SignificanceHER3 signaling, through ERK/MAPK, upregulates SorLA and SorLA controls the trafficking and stability of HER3 to support cancer proliferation and neratinib resistance.

cancer biology↗

bioRxiv2019

PP2A inhibitor PME-1 suppresses anoikis, and is associated with therapy relapse of PTEN-deficient prostate cancers

While organ-confined PCa is mostly therapeutically manageable, metastatic progression of PCa remains an unmet clinical challenge. Resistance to anoikis, a form of cell death initiated by cell detachment from the surrounding extracellular matrix, is one of the cellular processes critical for PCa progression towards aggressive disease. Therefore, further understanding of anoikis regulation in PCa might provide therapeutic opportunities. Here, we discover that PCa tumors with concomitantly compromised function of two tumor suppressor phosphatases, PP2A and PTEN, are particularly aggressive, having less than 50% 5-year secondary-therapy free patient survival. Functionally, overexpression of PME-1, a PP2A inhibitor protein, inhibits anoikis in PTEN-deficient PCa cells. In vivo, PME-1 inhibition increased apoptosis in in ovo PCa tumor xenografts, and attenuated PCa cell survival in zebrafish circulation. Molecularly, PME-1 deficient PCa cells display increased trimethylation at lysines 9 and 27 of histone H3 (H3K9me3 and H3K27me3), a phenotype corresponding to increased apoptosis sensitivity. In summary, we discover that PME-1 overexpression supports anoikis resistance in PTEN-deficient PCa cells. Clinically, the results identify PME-1 as a candidate biomarker for a subset of particularly aggressive PTEN-deficient PCa.

cancer biology↗

bioRxiv2018

SORLA-driven endosomal trafficking regulates the oncogenic fitness of HER2

Human epidermal growth factor receptor 2 (HER2) is an oncogene targeted by several kinase inhibitors and therapeutic antibodies. Endosomal trafficking of many other receptor tyrosine kinases regulates their oncogenic signaling, but the prevailing view is that HER2 is retained on the cell surface. Here we reveal that in cancer cells Sortilin related receptor 1 (SORLA; SORL1) forms a complex with HER2 and regulates its subcellular distribution by promoting recycling of endosomal HER2 back to plasma membrane. Expression of SORLA in cancer cell lines and bladder cancers correlates with HER2 levels. Depletion of SORLA targets HER2 to late endosomal/lysosomal compartments, impairs HER2-driven signaling and in vivo tumor growth. SORLA silencing also disrupts normal lysosome function and sensitizes anti-HER2 therapy sensitive and resistant cancer cells to lysosome-targeting cationic amphiphilic drugs. These findings reveal potentially important SORLA-dependent endosomal trafficking-linked vulnerabilities in HER2-driven cancers.

cell biology↗

bioRxiv2017

FiloQuant reveals increased filopodia density during DCIS progression

Filopodia are commonly observed cellular protrusions in vitro and in vivo. Defective filopodia formation is linked to several pathologies including cancer, wherein actively protruding filopodia, at the invasive front, and filopodia-mediated probing of the microenvironment accompanies cancer cell dissemination. Despite wide biological significance, delineating the function of these finger-like protrusions in more complex systems remains technically challenging, particularly hindered by lack of compatible methods to quantify filopodia properties. Here, we present FiloQuant, a freely available ImageJ plugin, to detect filopodia and filopodia-like protrusions in both fixed and live-cell microscopy data. We demonstrate that FiloQuant can extract quantifiable information including protrusion dynamics, density and length from multiple cell types and in a range of microenvironments, such as during collective or single cancer cell migration in 2D and 3D, in fixed neuronal cultures, in activated natural killer cells and in sprouting endothelial cells in vivo. In cellular models of breast ductal carcinoma in situ (DCIS) we reveal a link between filopodia formation at the cell-matrix interface, during collective invasion and in 3D tumour spheroids, with the previously reported local invasive potential of these breast cancer models in vivo. Finally, using intravital microscopy, we observed that tumour spheroids display prominent filopodia in vivo, supporting a potential role for these protrusions during tumorigenesis.

cell biology↗