Biology subjects

Nemeth, K.

Publications and source records attributed to Nemeth, K..

3 recordsLinked to original sources

bioRxiv2025

Soluble, but not precursor EGF induces intracrine signaling of the EGFR

EGFR is a transmembrane receptor tyrosine kinase regulating growth and survival in epithelial tissues. Its ligand, the epidermal growth factor (EGF), is produced as a membrane-anchored precursor (preEGF) that is proteolytically cleaved to release soluble EGF (sEGF). EGFR overexpression can convert it from a physiological regulator into an oncogenic driver. Therapeutic strategies targeting EGFR include monoclonal antibodies (mAbs) and tyrosine kinase inhibitors (TKIs). Although mAbs such as cetuximab initially block EGFR activity, tumors often develop resistance. Recent findings indicate that sEGF can activate EGFR within intracellular vesicles, promoting intracrine signaling that sustains proliferation despite extracellular inhibition. Here, we investigated the mechanism of intracrine EGFR signaling in the Golgi apparatus using confocal microscopy, FRET and fluorescence correlation spectroscopy. sEGF, but not preEGF, bound and induced EGFR dimerization and phosphorylation. Erlotinib, a membrane permeable TKI, effectively blocked phosphorylation, whereas extracellular cetuximab did not. These findings imply sEGF-induced intracrine EGFR signaling in the Golgi. Our results may shed light on a potential resistance mechanism to antibody treatment.

biophysics↗

bioRxiv2025

Deconvolution of Sparse-count RNA Sequencing Data for Tumor Cells Using Embedded Negative Binomial Distributions

Estimating tumor-specific transcript proportions from mixed bulk samples has potential to inform novel biology. However, estimation accuracy using existing methods in sparse-count data such as microRNA-seq and spatial transcriptomics has yet to be established. We generated a mixed small RNA benchmark dataset to demonstrate analytical challenges. To resolve them, we developed DeMixNB, a semi-reference-based deconvolution model assuming a sum of negative binomial distributions. Applications to miRNA-seq from 856 patients with breast cancer and 3,755 spatial spots from lung cancer generated either clinical or mechanistic insights into tumor cell plasticity. This supports the important utility of DeMixNB to investigate cancer RNomes.

bioinformatics↗

bioRxiv2024

A "torn bag mechanism" of small extracellular vesicle release via limiting membrane rupture of en bloc released amphisomes (amphiectosomes)

Recent studies showed an unexpected complexity of extracellular vesicle (EV) biogenesis pathways. We previously found evidence that human colorectal cancer cells in vivo release large multivesicular body-like structures en bloc. Here, we tested whether this large extracellular vesicle type is unique to colorectal cancer cells. We found that all cell types we studied (including different cell lines and cells in their original tissue environment) released multivesicular large EVs (MV-lEVs). We also demonstrated that upon spontaneous rupture of the limiting membrane of the MV-lEVs, their intraluminal vesicles (ILVs) escaped to the extracellular environment by a "torn bag mechanism". We proved that the MV-lEVs were released by ectocytosis of amphisomes (hence, we termed them amphiectosomes). Both ILVs of amphiectosomes and small EVs separated from conditioned media were either exclusively CD63 or LC3B positive. According to our model, upon fusion of multivesicular bodies with autophagosomes, fragments of the autophagosomal inner membrane curl up to form LC3B positive ILVs of amphisomes, while CD63 positive small EVs are of multivesicular body origin. Our data suggest a novel common release mechanism for small EVs, distinct from the exocytosis of multivesicular bodies or amphisomes, as well as the small ectosome release pathway.

cell biology↗