Project description:Methylthioadenosine Phosphorylase (MTAP) loss is one of the most frequent genetic alterations in Glioblastoma and has been associated with poor clinical outcomes in several cancer types. Here we used patient derived glioblastoma cell lines and manipulated MTAP status to create isogenic pairs with which to study the effects of this alteration on epigenetics, gene expression, and cell identity
Project description:Glioblastoma (GBM) is a lethal brain cancer exhibiting high levels of drug resistance, a feature partially imparted by tumor cell stemness. Recent work shows that homozygous MTAP deletion, a genetic alteration occurring in about half of all GBMs, promotes stemness in GBM cells. Exploiting MTAP loss-conferred deficiency in purine salvage, we demonstrate that purine synthesis blockade via treatment with L-Alanosine (ALA), an inhibitor of de novo purine synthesis, attenuates stemness and mitochondrial function of MTAP-deficient GBM cells. Here, we use RNA-Seq with ALA-treated patient-derived GBM cells to investigate the transcriptomic impact of long-term ALA treatment.
Project description:Abstract The aggressive nature and poor prognosis of lung cancer led us to explore the mechanisms driving disease progression. Utilizing our invasive cell-based model, we identified methylthioadenosine phosphorylase (MTAP) and confirmed its suppressive effects on tumorigenesis and metastasis, and patients with low MTAP expression displayed worse overall and progression-free survival. Mechanistically, accumulation of methylthioadenosine substrate in MTAP-deficient cells reduced the level of protein arginine methyltransferase 5 (PRMT5)-mediated symmetric dimethylarginine (sDMA) modification on proteins. Vimentin was revealed as a novel dimethyl-protein with less dimethylation level in response to MTAP loss. The sDMA modification on vimentin reduces its protein abundance and trivially affects its filamentous structure. In MTAP-loss cells, lower sDMA level prevents ubiquitination-mediated vimentin degradation, thereby stabilizing vimentin, contributing to cell invasion. This inverse association of the MTAP/PRMT5 axis with vimentin proteins was clinically corroborated. Taken together, we propose a novel mechanism of vimentin post-translational regulation and provide new insights in metastasis.
Project description:Methylthioadenosine Phosphorylase (MTAP) is a tumor suppressor gene that encodes an enzyme responsible for the catabolism of the polyamine byproduct 5′deoxy-5′-methylthioadenosine (MTA). To elucidate the mechanism by which MTAP inhibits tumor formation, we have created isogenic MTAP+ and MTAP- HT1080 fibrosarcoma cells. In this experiment we have performed expression array analysis on MTAP-, MTAP+, and MTAP+ cells treated with the MTAP inhibitor MT-DADMe-ImmA. Three biological replicates of each sample were grown and analyzed. M- is MTAP-. M+ is MTAP+, and M+I is MTAP treated with inhibitor (48 hours).
Project description:Homozygous deletion of methylthioadenosine phosphorylase (MTAP) is one of the most frequent genetic alterations in glioblastoma (GBM), but its pathologic consequences remain unclear. In this study, we report that loss of MTAP results in profound epigenetic reprogramming characterized by hypomethylation of PROM1/CD133-associated stem cell regulatory pathways. MTAP deficiency promotes glioma stem-like cell (GSC) formation with increased expression of PROM1/CD133 and enhanced tumorigenicity of GBM cells and is associated with poor prognosis in patients with GBM. As a combined consequence of purine production deficiency in MTAP-null GBM and the critical dependence of GSCs on purines, the enriched subset of CD133+ cells in MTAP-null GBM can be effectively depleted by inhibition of de novo purine synthesis. These findings suggest that MTAP loss promotes the pathogenesis of GBM by shaping the epigenetic landscape and stemness of GBM cells while simultaneously providing a unique opportunity for GBM therapeutics. SIGNIFICANCE: This study links the frequently mutated metabolic enzyme MTAP to dysregulated epigenetics and cancer cell stemness and establishes MTAP status as a factor for consideration in characterizing GBM and developing therapeutic strategies.
Project description:Methylthioadenosine Phosphorylase (MTAP) is a tumor suppressor gene that encodes an enzyme responsible for the catabolism of the polyamine byproduct 5′deoxy-5′-methylthioadenosine (MTA). To elucidate the mechanism by which MTAP inhibits tumor formation, we have created isogenic MTAP+ and MTAP- HT1080 fibrosarcoma cells. In this experiment we have performed expression array analysis on MTAP-, MTAP+, and MTAP+ cells treated with the MTAP inhibitor MT-DADMe-ImmA.
Project description:Genetic alterations that give rise to tumorigenesis result in altered epigenetic and gene expression profiles. We sought to identify and better understand potential consequences of MTAP deletion in glioblastoma by examining gene expression profiles of MTAP deleted and MTAP WT GBM cell lines. MTAP deletion results in accumulation of the abberant metabolite, MTA, with potential consequences to epigenetic regulation and signal transduction. We also examined the cellular response (gene expression) to purine deprivation with L-Alanosine treamment
Project description:By impairing histone demethylation and locking cells into a reprogramming-prone state, oncometabolites can partially mimic the process of induced pluripotent stem cell generation. Using a systems biology approach, combining mathematical modelling, computation, and proof-of-concept studies with live cells, we found that an oncometabolite-driven pathological version of nuclear reprogramming increases the speed and efficiency of dedifferentiating committed epithelial cells into stem-like states with only a minimal core of stemness transcription factors. Our biomathematical model, which introduces nucleosome modification and epigenetic regulation of cell differentiation genes to account for the direct effects of oncometabolites on nuclear reprogramming, demonstrates that oncometabolites markedly lower the “energy barriers” separating non-stem and stem cell attractors, diminishes the average time of nuclear reprogramming, and increases the size of the basin of attraction of the macrostate occupied by stem cells. These findings establish for the first time the concept of oncometabolic nuclear reprogramming of stemness as a novel metabolo-epigenetic mechanism for generation of cancer stem-like cells.
Project description:Glioblastoma is the most lethal form of brain tumor with a recurrence rate of almost 90% and a survival time of only 15 months post-diagnosis. It is a highly heterogeneous, aggressive, and extensively studied tumor. Multiple studies have proposed therapeutic approaches to mitigate or improve the survival for patients with glioblastoma. In this article, we review the loss of the 5'-methylthioadenosine phosphorylase (MTAP) gene as a potential therapeutic approach for treating glioblastoma. MTAP encodes a metabolic enzyme required for the metabolism of polyamines and purines leading to DNA synthesis. Multiple studies have explored the loss of this gene and have shown its relevance as a therapeutic approach to glioblastoma tumor mitigation; however, other studies show that the loss of MTAP does not have a major impact on the course of the disease. This article reviews the contrasting findings of MTAP loss with regard to mitigating the effects of glioblastoma, and also focuses on multiple aspects of MTAP loss in glioblastoma by providing insights into the known findings and some of the unexplored areas of this field where new approaches can be imagined for novel glioblastoma therapeutics.
Project description:MTAP is an enzyme and found deleted in various cancers, but its role in lung adenoacrcinoma is still unclear. This study sought to investigate the effects of MTAP on the biological behavior and global gene expression profiles in lung adenocacinoma cells. We used expression microarrays to identify the global gene alterations in lung adenocacinoma cell line, CL1-5 cells after ectopically expressing V5-tagged MTAP gene.