Pogodaeva, S. S. | Search bioRxiv

bioRxiv2025

NONO as a Sensor of Intracellular Oxidation: Relevance to Neuroblastoma Cell Death

Neuroblastoma, a transcriptionally driven pediatric malignancy, exhibits a remarkable clinical and biological heterogeneity. Two major subtypes, the adrenergic and mesenchymal, are differentially governed by a subset of transcription factors that comprise the core regulatory circuit (CRC). The former subtype is often associated with MYCN amplification and is particularly aggressive and therapy-resistant, underscoring the need for novel targets. Here, we identify the multifunctional non-POU domain-containing octamer-binding (NONO) protein as a guardian of individual CRC genes, thereby contributing to survival of neuroblastoma cells with different MYCN copy numbers. Intracellular oxidation in response to auranofin, an inhibitor of thioredoxin reductase 1, rapidly down-regulated the amounts of NONO mRNA and protein in MYCN-amplified Kelly cell line. Conversely, NONO knockdown with RNA interference (siNONO) also triggered intracellular oxidation. These effects were less pronounced in the SK-N-AS cell line carrying a single MYCN copy, as well as in non-malignant HS5 fibroblasts. In Kelly cells, siNONO attenuated auranofin-induced activation of CRC genes HAND2 and PHOX2B. In line with preferential effects on NONO abundance, the Kelly cells were more sensitive than single MYCN copy counterparts to combinations of a sublethal concentration of auranofin with siNONO. Importantly, MYCN-amplified cells demonstrated a significantly suppressed clonogenic survival 14 days after transient exposure to these combinations compared with each agent alone; HS5 fibroblasts were largely spared. Our findings 1) establish NONO as a redox sensor, a non-trivial role for transcriptional proteins, and 2) justify the strategy of therapeutic targeting of MYCN-amplified tumors vulnerable to oxidative stress. Key pointsO_LINONO, a master regulator of the core regulatory circuit (CRC) in MYCN-amplified neuroblastoma, is rapidly down-regulated by auranofin-induced intracellular oxidation. C_LIO_LINONO knockdown synergizes with auranofin in triggering individual CRC gene deregulation and lethal oxidative stress preferentially in MYCN-amplified cells. C_LI

cancer biology↗

bioRxiv2024

Atox1-Cyclin D1 Loop Activity is Critical for Survival of Tumors with Inactivated TP53

The search for relevant molecular targets is one of the main tasks of modern tumor chemotherapy. To successfully achieve this, it is necessary to have the most complete understanding of the functioning of the cells transcriptional apparatus, particularly related to proliferation. The p53 protein plays an important role in regulating processes such as apoptosis, repair, and cell division, and the loss of its functionality often accompanies various types of tumors and contributes to the development of chemoresistance. Additionally, the proliferative activity of tumor cells is closely related to the metabolism of transition metals. For example, the metallochaperone Atox1 - a copper transporter protein - acts as a transcription activator for cyclin D1, promoting progression through the G1/S phase of the cell cycle. On the other hand, p53 suppresses cyclin D1 at the transcriptional level, thereby these proteins have divergent effects on cell cycle progression. However, the contribution of the interaction between these proteins to cell survival is poorly understood. This work demonstrates that there not only exists a positive feedback loop between Atox1 and cyclin D1, but also that the activity of this loop depends on the status of the TP53 gene. Upon inactivation of TP53 in A549 and HepG2 cell lines, the expression of ATOX1 and CCND1 genes is enhanced, and their suppression in these cells leads to pronounced apoptosis. This fundamental observation may be useful in selecting more precise interventions for combined therapy of p53-negative tumors.

cancer biology↗