Restoring Mitochondrial Quantity and Quality to Reverse Warburg Effect and Drive Tumor Differentiation
Ontology highlight
ABSTRACT: Reduced mitochondrial quality and quantity in tumors is associated with dedifferentiation and increased malignancy. However, it remains unclear how to restore mitochondrial quantity and quality in tumors, and whether mitochondrial restoration can drive tumor differentiation. Our study shows that restoring mitochondrial function using retinoic acid (RA) to boost mitochondrial biogenesis and a mitochondrial uncoupler to enhance respiration synergistically drives neuroblastoma differentiation and inhibits proliferation. U-13C-glucose/glutamine isotope tracing revealed a metabolic shift from the pentose phosphate pathway to oxidative phosphorylation, accelerating the TCA cycle and switching substrate preference from glutamine to glucose. These effects were reversed by ETC inhibitors or in ρ0 cells lacking mtDNA, emphasizing the necessity of mitochondrial function for differentiation. Dietary RA and uncoupler treatment promoted tumor differentiation in an orthotopic neuroblastoma xenograft model, evidenced by neuropil production and Schwann cell recruitment. Single-cell RNA sequencing analysis of the orthotopic xenografts revealed that this strategy effectively eliminated the stem cell population, promoted differentiation, and increased mitochondrial gene signatures along the differentiation trajectory, which could potentially significantly improve patient outcomes. Collectively, our findings establish a mitochondria-centric therapeutic strategy for inducing tumor differentiation, suggesting that maintaining/driving differentiation in tumor requires not only ATP production but also continuous ATP consumption and sustained ETC activity.
Project description:Reduced mitochondrial quality and quantity in tumors is associated with dedifferentiation and increased malignancy. However, it remains unclear how to restore mitochondrial quantity and quality in tumors, and whether mitochondrial restoration can drive tumor differentiation. Our study shows that restoring mitochondrial function using retinoic acid (RA) to boost mitochondrial biogenesis and a mitochondrial uncoupler to enhance respiration synergistically drives neuroblastoma differentiation and inhibits proliferation. U-13C-glucose/glutamine isotope tracing revealed a metabolic shift from the pentose phosphate pathway to oxidative phosphorylation, accelerating the TCA cycle and switching substrate preference from glutamine to glucose. These effects were reversed by ETC inhibitors or in ρ0 cells lacking mtDNA, emphasizing the necessity of mitochondrial function for differentiation. Dietary RA and uncoupler treatment promoted tumor differentiation in an orthotopic neuroblastoma xenograft model, evidenced by neuropil production and Schwann cell recruitment. Single-cell RNA sequencing analysis of the orthotopic xenografts revealed that this strategy effectively eliminated the stem cell population, promoted differentiation, and increased mitochondrial gene signatures along the differentiation trajectory, which could potentially significantly improve patient outcomes. Collectively, our findings establish a mitochondria-centric therapeutic strategy for inducing tumor differentiation, suggesting that maintaining/driving differentiation in tumor requires not only ATP production but also continuous ATP consumption and sustained ETC activity.
Project description:Neuroblastoma is a pediatric cancer characterized by variable outcomes ranging from spontaneous regression to life-threatening progression. High-risk neuroblastoma patients receive myeloablative chemotherapy with hematopoietic stem-cell transplant followed by adjuvant retinoid differentiation treatment. However, the overall survival remains low; hence, there is an urgent need for alternative therapeutic approaches. One feature of high-risk neuroblastoma is the high level of DNA methylation of putative tumor suppressors. Combining the reversibility of DNA methylation with the differentiation-promoting activity of retinoic acid (RA) could provide an alternative strategy to treat high-risk neuroblastoma. Here we show that treatment with the DNAdemethylating drug 5-Aza-deoxycytidine (AZA) restores high-risk neuroblastoma sensitivity to RA. Combined systemic distribution of AZA and RA impedes tumor growth and prolongs survival. Genomewide analysis of treated tumors reveals that this combined treatment rapidly induces a HIF2α-associated hypoxia-like transcriptional response followed by an increase in neuronal gene expression and a decrease in cell-cycle gene expression. A small-molecule inhibitor of HIF2α activity diminishes the tumor response to AZA+RA treatment, indicating that the increase in HIF2α levels is a key component in tumor response to AZA+RA. The link between increased HIF2α levels and inhibited tumor growth is reflected in large neuroblastoma patient datasets. Therein, high levels of HIF2α, but not HIF1α, significantly correlate with expression of neuronal differentiation genes and better prognosis but negatively correlate with key features of high-risk tumors, such as MYCN amplification. Thus, contrary to previous studies, our findings indicate an unanticipated tumor-suppressive role for HIF2α in neuroblastoma.
Project description:Neuroblastoma is a pediatric cancer characterized by variable outcomes ranging from spontaneous regression to life-threatening progression. High-risk neuroblastoma patients receive myeloablative chemotherapy with hematopoietic stem-cell transplant followed by adjuvant retinoid differentiation treatment. However, the overall survival remains low; hence, there is an urgent need for alternative therapeutic approaches. One feature of high-risk neuroblastoma is the high level of DNA methylation of putative tumor suppressors. Combining the reversibility of DNA methylation with the differentiation-promoting activity of retinoic acid (RA) could provide an alternative strategy to treat high-risk neuroblastoma. Here we show that treatment with the DNA demethylating drug 5-Aza-deoxycytidine (AZA) restores high-risk neuroblastoma sensitivity to RA. Combined systemic distribution of AZA and RA impedes tumor growth and prolongs survival. Genomewide analysis of treated tumors reveals that this combined treatment rapidly induces a HIF2α-associated hypoxia-like transcriptional response followed by an increase in neuronal gene expression and a decrease in cell-cycle gene expression. A small-molecule inhibitor of HIF2α activity diminishes the tumor response to AZA+RA treatment, indicating that the increase in HIF2α levels is a key component in tumor response to AZA+RA. The link between increased HIF2α levels and inhibited tumor growth is reflected in large neuroblastoma patient datasets. Therein, high levels of HIF2α, but not HIF1α, significantly correlate with expression of neuronal differentiation genes and better prognosis but negatively correlate with key features of high-risk tumors, such as MYCN amplification. Thus, contrary to previous studies, our findings indicate an unanticipated tumor-suppressive role for HIF2α in neuroblastoma.
Project description:The main scientific objective of the project was to investigate whether Lamin A/C could be involved in neuroblastoma differentiation. Moreover, taking into account the significance of differentiation stage in the neuroblastoma tumor progression we have also studied a possible role of Lamin A/C in the tumorigenesis of this neuronal cancer. As differentiating stimulus we used the all-trans retinoic acid (RA), the most effective compound which has been shown to induce differentiation in neuroblastoma cells. To get insight into the impairment of cell differentiation produced by the LMNA (Lamin A/C) silencing in SHSY5Y cells, we compared the gene expression profile of control and silenced cells both in Retinoic Acid treated and untreated samples, using the one-color Agilent microarray platform. Four condition experiment: cells infected with a mock vector (Mock cells), treated and untreated with retinoic acid (RA); cells infected with a silencing vector for LMNA (LMNA-KD cells), treated and untreated with retinoic acid.
Project description:Retinoic acid (RA) is a standard-of-care neuroblastoma drug thought to act primarily via differentiation. However, this has never been conclusively demonstrated in vivo. Curiously, RA has little effect shrinking primary human tumors when applied in upfront treatment but can eliminate neuroblastoma cells from the bone marrow during consolidation therapy—a discrepancy that has never been explained. To investigate this, we treated a large cohort of neuroblastoma cell lines with RA and observed that the most RA-sensitive cells tended to undergo apoptosis or senescence, rather than differentiation. We conducted genome-wide CRISPR knockout screens under RA treatment, which identified BMP signaling as controlling the apoptosis/senescence vs differentiation cell fate decision and RA’s overall potency. We then conducted integrative analysis of high throughput ChIP-seq and RNA-seq data, which indicates that downstream BMP and RA transcription factors cooperate to determine cell fate, following exposure to RA.
Project description:Retinoic acid (RA) is a standard-of-care neuroblastoma drug thought to act primarily via differentiation. However, this has never been conclusively demonstrated in vivo. Curiously, RA has little effect shrinking primary human tumors when applied in upfront treatment but can eliminate neuroblastoma cells from the bone marrow during consolidation therapy—a discrepancy that has never been explained. To investigate this, we treated a large cohort of neuroblastoma cell lines with RA and observed that the most RA-sensitive cells tended to undergo apoptosis or senescence, rather than differentiation. We conducted genome-wide CRISPR knockout screens under RA treatment, which identified BMP signaling as controlling the apoptosis/senescence vs differentiation cell fate decision and RA’s overall potency. We then conducted integrative analysis of high throughput ChIP-seq and RNA-seq data, which indicates that downstream BMP and RA transcription factors cooperate to determine cell fate, following exposure to RA.
Project description:High-risk neuroblastoma is often distinguished by amplification of MYCN and loss of differentiation potential with tumors refractory to retinoic acid differentiation based therapies. Here, we leverage high-throughput drug screening of epigenetic targeted therapies across a large and diverse tumor cell line panel to uncover the hypersensitivity of neuroblastoma cells to GSK-J4, a small molecule dual inhibitor of H3K27 demethylases UTX and JMJD3. Mechanistically, GSK-J4 induced neuroblastoma differentiation and ER stress with accompanying upregulation of PUMA and apoptosis induction. Retinoic acid (RA)-resistant neuroblastoma cells were sensitive to GSK-J4. Additionally, GSK-J4 was effective at blocking the growth of chemorefractory and patient-derived xenograft models of high-risk neuroblastoma in vivo. Further, GSK-J4 and RA combined to induce differentiation, ER-stress and limit the growth of neuroblastomas resistant to either drug alone. In MYCN-amplified neuroblastoma, which is the most prevalent driver gene alteration in the refractory population, PUMA induction by GSK-J4 sensitized tumors to the BCL-2 inhibitor venetoclax, demonstrating that epigenetic targeted therapies and BH3 mimetics can be rationally combined to treat high-risk subset of neuroblastoma. Therefore, H3K27 demethylation inhibition is a promising therapeutic target to treat high-risk neuroblastoma, and H3K27 demethylation can be part of rational combination therapies to induce robust anti-neuroblastoma activity.
Project description:Neuroblastoma (NB) arises from neural crest cells (NCCs) secondary to a block in differentiation. Retinoic acid (RA) differentiation therapy has limited therapeutic efficacy, and the mechanisms preventing terminal differentiation remain elusive. We found that the chromatin modifier CHAF1A restricts neuronal differentiation and promotes NB oncogenesis. CHAF1A blocks NC differentiation into mature neurons in both human NCCs and zebrafish models. CHAF1A gain-of-function promotes cell malignancy, blocks RA-induced differentiation, and is sufficient to induce NB tumor formation. Mechanistically, CHAF1A blocks NB differentiation by repressing gene expression programs promoting neuronal development and differentiation, and rewiring polyamine metabolism. Targeting polyamine synthesis restores NB sensitivity to RA therapy. Our results demonstrate that CHAF1A critically contributes to NB oncogenesis by blocking neuronal differentiation and reprogramming cell metabolism.