Browsing by Author "Ljungman, Mats"

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    Regulation of cellular sterol homeostasis by the oxygen responsive noncoding RNA lincNORS
    (Nature Publishing Group, 2020-09-21) Wu, Xue; Niculite, Cristina M.; Preda, Mihai Bogdan; Rossi, Annalisa; Tebaldi, Toma; Butoi, Elena; White, Mattie K.; Tudoran, Oana M.; Petrusca, Daniela N.; Jannasch, Amber S.; Bone, William P.; Zong, Xingyue; Fang, Fang; Burlacu, Alexandrina; Paulsen, Michelle T.; Hancock, Brad A.; Sandusky, George E.; Mitra, Sumegha; Fishel, Melissa L.; Buechlein, Aaron; Ivan, Cristina; Oikonomopoulos, Spyros; Gorospe, Myriam; Mosley, Amber; Radovich, Milan; Davé, Utpal P.; Ragoussis, Jiannis; Nephew, Kenneth P.; Mari, Bernard; McIntyre, Alan; Konig, Heiko; Ljungman, Mats; Cousminer, Diana L.; Macchi, Paolo; Ivan, Mircea; Medicine, School of Medicine
    We hereby provide the initial portrait of lincNORS, a spliced lincRNA generated by the MIR193BHG locus, entirely distinct from the previously described miR-193b-365a tandem. While inducible by low O2 in a variety of cells and associated with hypoxia in vivo, our studies show that lincNORS is subject to multiple regulatory inputs, including estrogen signals. Biochemically, this lincRNA fine-tunes cellular sterol/steroid biosynthesis by repressing the expression of multiple pathway components. Mechanistically, the function of lincNORS requires the presence of RALY, an RNA-binding protein recently found to be implicated in cholesterol homeostasis. We also noticed the proximity between this locus and naturally occurring genetic variations highly significant for sterol/steroid-related phenotypes, in particular the age of sexual maturation. An integrative analysis of these variants provided a more formal link between these phenotypes and lincNORS, further strengthening the case for its biological relevance.
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    Transcriptomic Analysis of Diffuse Intrinsic Pontine Glioma (DIPG) Identifies a Targetable ALDH-Positive Subset of Highly Tumorigenic Cancer Stem-like Cells
    (American Association for Cancer Research, 2021) Surowiec, Rachel K.; Ferris, Sarah F.; Apfelbaum, April; Espinoza, Carlos; Mehta, Ranjit K.; Monchamp, Karamoja; Sirihorachai, Veerin R.; Bedi, Karan; Ljungman, Mats; Galban, Stefanie; Radiology and Imaging Sciences, School of Medicine
    Understanding the cancer stem cell (CSC) landscape in diffuse intrinsic pontine glioma (DIPG) is desperately needed to address treatment resistance and identify novel therapeutic approaches. Patient-derived DIPG cells demonstrated heterogeneous expression of aldehyde dehydrogenase (ALDH) and CD133 by flow cytometry. Transcriptome-level characterization identified elevated mRNA levels of MYC, E2F, DNA damage repair (DDR) genes, glycolytic metabolism, and mTOR signaling in ALDH+ compared with ALDH-, supporting a stem-like phenotype and indicating a druggable target. ALDH+ cells demonstrated increased proliferation, neurosphere formation, and initiated tumors that resulted in decreased survival when orthotopically implanted. Pharmacologic MAPK/PI3K/mTOR targeting downregulated MYC, E2F, and DDR mRNAs and reduced glycolytic metabolism. In vivo PI3K/mTOR targeting inhibited tumor growth in both flank and an ALDH+ orthotopic tumor model likely by reducing cancer stemness. In summary, we describe existence of ALDH+ DIPGs with proliferative properties due to increased metabolism, which may be regulated by the microenvironment and likely contributing to drug resistance and tumor recurrence. IMPLICATIONS: Characterization of ALDH+ DIPGs coupled with targeting MAPK/PI3K/mTOR signaling provides an impetus for molecularly targeted therapy aimed at addressing the CSC phenotype in DIPG.