Project description:The dolichyl-diphosphooligosaccharide-protein glycosyltransferase non-catalytic subunit (DDOST) is a key component of the oligosaccharyltransferase complex catalyzing N-linked glycosylation in the endoplasmic reticulum lumen. DDOST is associated with several cancers and congenital disorders of glycosylation. However, its role in pancreatic cancer remains elusive, despite its enriched pancreatic expression. Using quantitative mass spectrometry, we identify 30 differentially expressed proteins and phosphopeptides (DEPs) after DDOST knockdown in the pancreatic ductal adenocarcinoma (PDAC) cell line PA-TU-8988T. We evaluated DDOST / DEP protein-protein interaction networks using STRING database, correlation of mRNA levels in pancreatic cancer TCGA data, and biological processes annotated to DEPs in Gene Ontology database. The inferred DDOST regulated phenotypes were experimentally verified in two PDAC cell lines, PA-TU-8988T and BXPC-3. We found decreased proliferation and cell viability after DDOST knockdown, whereas ER-stress, ROS-formation and apoptosis were increased. In conclusion, our results support an oncogenic role of DDOST in PDAC by intercepting cell stress events and thereby reducing apoptosis. As such, DDOST might be a potential biomarker and therapeutic target for PDAC.
Project description:Characterization of the protein composition of exosomes and subpopulations of cells from four human PDAC cell lines (BxPC-3, PANC-1, T3M4, and MIA PaCa-2), via liquid chromatography electrospray ionization tandem mass spectrometry (LC/ESI–MS/MS).
Project description:We report that m6A reader IGF2BP2 participates in the regulation of glutamine metabolism in AML. To further clarify whether IGF2BP2 knockdown (KD) leads to translational inhibition, we perform Ribo-seq in control and IGF2BP2 KD cells.
Project description:C-Myc overexpression is an important molecular hallmark of pancreatic ductal adenocarcinoma (PDAC), but directly targeting c-Myc is extremely challenging. Identifying key upstream factors involved in c-Myc overexpression provides promising indirect targets for c-Myc. Herein, the long noncoding RNAs (lncRNAs) highly expressed in PDAC and significantly correlated with c-Myc expression were identified using RNA sequencing datasets. Among them, LINC01963 was found to interact with c-Myc, as confirmed by RNA pull-down and RIP-qPCR assays. Furthermore, high LINC01963 expression was correlated with poor PDAC prognosis, and functional studies demonstrated that its knockdown inhibited PDAC cell proliferation and xenograft tumor growth. Mechanistic studies identified LINC01963 as a key regulator of c-Myc stability, consequently affecting cell cycle through the c-Myc/p21-related signaling pathways. Further investigation revealed that LINC01963 enhanced N6-methyladenosine (m6A) modification of c-Myc mRNA by protecting methyltransferase-like 3 (METTL3) protein from KDM1B-mediated ubiquitin-proteasome degradation. Intriguingly, LINC01963 also stabilized c-Myc mRNA by facilitating the formation of a ternary complex with insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) and m6A-modified c-Myc. Our study reveals that LINC01963 promotes PDAC tumorigenesis through METTL3/IGF2BP2 axis-coordinated regulation of c-Myc, suggesting a new strategy for indirectly targeting c-Myc.
Project description:T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignant leukemia with extreme limited treatment for relapsed patients. N6‐methyladenosine (m6A) reader Insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) participates in the initiation and growth of cancers by communicating with various targets. Here, we found IGF2BP2 is highly expressed in T-ALL. Gain and loss of IGF2BP2 demonstrated IGF2BP2 was essential for T-ALL cell proliferation in vitro and loss of IGF2BP2 prolonged animal survival in a human T-ALL xenograft model. Mechanistically, IGF2BP2 directly bound to T-ALL oncogene NOTCH1 via an m6A dependent manner. Furthermore, we identified a small-molecule IGF2BP2 inhibitor JX5 and treatment of T-ALL with JX5 showed similar functions as knockdown of IGF2BP2. These findings not only shed light on the role of IGF2BP2 in T-ALL, but also provide an alternative γ‑Secretase inhibitors (GSI) therapy to treat T-ALL.
Project description:Purpose: Due to its high metastatic proclivity, pancreatic ductal adenocarcinoma (PDAC) is one of the most deadly types of cancer. Therefore, it is imperative to better understand how the disease spreads as it progresses. Using a novel genetically engineered mouse model that allows us to isolate a subpopulation of cancer cells with superior metastatic capacity, we show that this aggressive phenotype correlates exclusively with a strong hypoxia signature. We subsequently identified the novel hypoxia-inducible gene Blimp1, which appears to play a critical role in regulating the hypoxic response upon its induction. Furthermore, genetic ablation of Blimp1 greatly reduces the level of metastasis in a PDAC mouse model. The nature of this Blimp1-regulated hypoxia signature is very unstable, since the seeded metastatic lesions mostly re-adopt similar transcriptomic profiles as the primary tumors. In conclusion, our results offer a potential mechanistic insight into how hypoxia drives metastasis in PDAC. Methods: The liver metastasis cell line 688M was subjected to control or knockdown of Blimp1 before assay. Cells ere validated for knockdown efficiency and then cultured under normoxia and hypoxia (0.5% O2) for 24 hours before preparation for ATAC-Seq (total of 4 groups with 2 technical replicates per group, overall 8 samples). Reference for ATACSeq: Buenrostro et al. 2013. Nat Methods 12:1213-8. Results: For the control knockdown group, 0.5% O2 culture (hypoxia) for 24 hours induced dramatic changes in global genome accessibility, and Blimp1 knockdown appeared to induce minimum changes in chromatin accessibility under hypoxia or normoxia (20% O2). Conclusions: Compared to our RNASeq profiles of the same liver met PDAC cell line under identical conditions, Blimp1 appeared to impact a global gene expression changes under hypoxia that is not associated with a corresponding changes of chromatin accessibility.