Biology subjects

Pradella, D.

Publications and source records attributed to Pradella, D..

3 recordsLinked to original sources

bioRxiv2025

miRISC inhibition causes mitotic defects and synergizes with genotoxic agents in cancers

Although individual microRNAs (miRNAs) can have tumorigenic or tumor-suppressive properties, their overall role in cancer remains controversial. Here, we show that cancer tissues and cell lines are characterized by preferential accumulation of the high-molecular-weight miRNA-induced silencing complex (HMWR), the functionally active form of the effector complex responsible for miRNA-mediated gene repression. Experimentally induced disassembly of the HMWR impairs the growth of human tumor xenografts and of autochthonous tumors in mouse models of human cancer in vivo. Furthermore, disassembly of the HMWR increases chromosome mis-segregation, which synergized with genotoxic agents to potentiate cancer cell vulnerability and improve therapeutic response. These findings suggest pharmacologic inhibition of HMWR as a novel anti-cancer strategy.

cancer biology↗

bioRxiv2025

Oncogene Silencing via ecDNA Micronucleation

Extrachromosomal DNA (ecDNA) contributes to cancer genome instability by enabling high-copy oncogene amplification, intratumoural heterogeneity and rapid genetic change. Micronuclei (MN) are frequently observed in chromosomally unstable cancers, yet their origins and relevance in ecDNA-driven tumours remain incompletely understood. Here, we investigate the relationship between ecDNA segregation errors and MN formation. We find that ecDNA frequently localizes to MN and represents a prominent source of MN content in ecDNA-positive cancer cells. Mitotic clustering of oncogene-bearing ecDNAs is associated with asymmetric inheritance and mis-segregation into MN. Transfer of oncogenes from ecDNA into MN is accompanied by reduced transcriptional output. Single-MN sequencing shows that individual MN are enriched for ecDNA to a degree that exceeds expectations from stochastic mis-segregation and that in MN oncogenes originating from multiple distinct ecDNAs coalesce. Using live-cell imaging, we observe that cells inheriting ecDNA-positive MN show limited proliferative capacity and an increased likelihood of cell death. In neuroblastoma patients with MYCN-amplified ecDNA, higher frequencies of ecDNA-positive MN at diagnosis are associated with improved event-free and overall survival. Together, these findings link ecDNA mis-segregation to MN formation and reduced cellular fitness, suggesting that ecDNA-positive MN may reflect a state of impaired oncogenic ecDNA function with potential relevance for clinical outcome.

cancer biology↗

bioRxiv2023

Immortalization and transformation of primary cells mediated by engineered ecDNAs

Focal gene amplifications are among the most common cancer-associated mutations, but their evolution and contribution to tumorigenesis have proven challenging to recapitulate in primary cells and model organisms. Here we describe a general approach to engineer large (>1 Mbp) focal amplifications mediated by extrachromosomal circular DNAs (ecDNAs, also known as "double minutes") in a spatiotemporally controlled manner in cancer cell lines and in primary cells derived from genetically engineered mice. With this strategy, ecDNA formation can be coupled with expression of fluorescent reporters or other selectable markers to enable the identification and tracking of ecDNA-containing cells. We demonstrate the feasibility of this approach by engineering MDM2-containing ecDNAs in near-diploid human cells, showing that GFP expression can be used to track ecDNA dynamics under physiological conditions or in the presence of specific selective pressures. We also apply this approach to generate mice harboring inducible Myc- and Mdm2-containing ecDNAs analogous to those spontaneously occurring in human cancers. We show that the engineered ecDNAs rapidly accumulate in primary cells derived from these animals, promoting proliferation, immortalization, and transformation.

cancer biology↗