Biology subjects

Benhamou, L.-R. E.

Publications and source records attributed to Benhamou, L.-R. E..

3 recordsLinked to original sources

bioRxiv2025

Noncoding RNA elements within MYCN mRNA are potent autonomous drivers of oncogenesis.

Neuroblastoma (NB) is a highly metastatic pediatric cancer arising from the neural crest lineage. Genetic amplification of the MYCN proto-oncogene is a defining feature of NB, present in about 20% of all cases. The let-7 tumor suppressor microRNA targets the 3 UTR of MYCN mRNA. We previously demonstrated that the 3 UTR of MYCN mRNA acquires the ability to sequester let-7 in MYCN-amplified (MA) disease, thus inhibiting its function. This work established that a noncoding element within an oncogenic mRNA can contribute independently to disease pathology and genetic patterning. To further investigate the roles of noncoding RNA elements within the MYCN mRNA, we engineered cells expressing either MYCN-ORF (MYCN open reading frame only), MYCN-GL (full-length MYCN mRNA from the intact genetic locus), and Null-GL (full-length MYCN mRNA variant where EGFP replaces MYCN protein). We observe that all constructs enhance growth compared to controls in vitro and in vivo. MYCN-GL-expressing cells displayed the most robust growth in vitro despite containing multiple regulatory RNA elements. Remarkably, the Null-GL construct induces cells to grow as fast or faster than MYCN-ORF-expressing cells. Animal studies further confirmed these observations, where the Null-GL-driven tumors had the highest incidence and lowest latency, followed by MYCN-GL and then MYCN-ORF. Further, through NGS analysis, let-7, miR-101, and miR-34a targets are enriched in both MYCN-GL and Null-GL expressing cells. Thus, the 3UTR of MYCN, which is also targeted by these microRNAs, may interact with them in MYCN-GL and Null-GL cells to deliver a protective effect for the mRNA targets of these microRNAs. We also observed more dynamic differential gene expression in the -GL constructs than in ORF and GFP-expressing cells. In addition, MYCN-GL and Null-GL expressing cells are similarly enriched in gene ontology pathways for cancer, RNA metabolism, and microRNA processing pathways as compared to ORF and GFP. Whole genome sequencing also revealed more similarities in copy number variation in MYCN-GL and Null-GL than in ORF and GFP, suggesting that these constructs may provide selective pressure to favor specific CNV patterns. These observations show that full-length MYCN mRNA containing noncoding regulatory elements are more robust drivers of cell growth and oncogenicity than MYCN protein alone and provide insights into the mechanisms of oncogenic contribution. These results open an exciting door for our understanding of NB pathology and genetic patterning and have broad implications for other oncogene-driven cancers.

cancer biology↗

bioRxiv2024

Novel sex-biased outcomes in neuroblastoma are associated with distinct gene expression and chromosomal loss patterns.

The worst patient outcomes in neuroblastoma are driven by high-risk disease1,2, which is divided into similarly sized MYCN amplified and MYCN non-amplified patient subgroups3. Male patients have been reported to have slightly worse outcomes than females in all-patient analyses of multiple studies3,4. However, we show here that in MYCN non- amplified high-risk and stage 4s low-risk disease, female patients have significantly worse overall survival than males. Female MYCN non-amplified high-risk patients highly express H19 and DLK1, both of which drive cell growth in vitro and are associated with worse outcomes in females but not males. Further, chromosome-specific expression analysis of these patients reveals broad sex disparities in chromosomal patterning, including female-specific retention of chromosome 11q, a pattern typically reserved for MYCN-amplified disease5,6. Finally, we show that H19, a known let-7 microRNA target7, sequesters let-7 in females, providing a rationale for worse female survival and reconciling retention of chromosome 11q. We propose that this novel sex-based outcome disparity is driven by let-7 inhibition, expanding on a model of neuroblastoma development where let-7 mitigation is central to disease pathology8.

cancer biology↗

bioRxiv2024

High dose ω3 eicosapentaenoic acid and docosahexaenoic acid block, whereas ω6 arachidonic acid accelerates, MYCN-driven tumorigenesis in vivo

Background/ObjectivesNeuroblastoma is a genetically diverse, highly metastatic pediatric cancer accounting for 15% of childhood cancer deaths despite only having ~8% of childhood cancer incidence. The current standard of care for high-risk disease is highly genotoxic. This, combined with less than 50% survival in high-risk disease and an abysmal 5% survival in relapsed cases, makes discovering novel, effective, and less toxic treatments essential. MethodsA prophylactic syngeneic mouse model was used to test high-dose lipid-mediator highly unsaturated fatty acids on tumorigenesis. Wild-type mice were gavaged with 12.3-14.6 g/d (adult human equivalent) omega-3 EPA, DHA, or oxidation-resistant bis allylic deuterated DHA (D-DHA) and 4.6-6.0 g/d arachidonic acid (ARA). At seven days, MYCN-expressing murine neuro-2a cells syngeneic to the gavaged mice were injected subcutaneously. Oral gavage continued for 10-20 d post-injection when tumors and tissues were harvested. ResultsFifty percent of control (not gavaged) animals form tumors (4/8) at about 10 d. High-dose DHA, D-DHA, and EPA block tumor formation completely in n=8 or 10 animals. In contrast, {omega}6 arachidonic acid (4.6-6.0 g/d) enhances tumor formation (6/10 tumors) and reduces latency (5.5 to 10 days)compared to control. Co-delivery of ARA and EPA results in a reduced tumor burden analogous to the control group, suggesting that EPA directly opposes the mechanism of ARA-mediated tumor formation. DHA acts through a non-oxidative mechanism. ConclusionsSustained high dose {omega}3 (weeks/months) is safe and well tolerated in humans. These results suggest that {omega}3 DHA and EPA delivery at ultra-high doses may represent a viable low-toxicity therapy for neuroblastoma. Simple SummaryPediatric Neuroblastoma has an overall mortality rate above 50%, and the current standard of care consists of highly genotoxic compounds. The biological actions of omega-6 ({omega}6) and omega-3 ({omega}3) highly unsaturated fatty acids (HUFA) generally oppose one another with the {omega}6 HUFA signaling for inflammation and angiogenesis (new blood vessel formation). Prolonged use of ultrahigh dose (15-20 g/d) {omega}3 HUFA has shown efficacy in catastrophic human traumatic brain injury and is well tolerated. Tumors form in about 50% of mice in our pediatric neuro-blastoma model. We show that 12-14 g/d adult human equivalent doses of {omega}3 EPA or DHA, as well as an oxidation-resistant form of DHA (D-DHA), completely block tumor formation, whereas a dose of about 5 g/d of {omega}6 ARA enhances tumorigenesis. Our data suggest that ultra-high dose {omega}3 therapy should be carefully investigated as a low-toxicity approach to neuroblastoma intervention.

cancer biology↗