Genetic and Epigenetic Characterization of Growth Hormone–Secreting Pituitary Tumors

  • Niko Välimäki
    1Department of Medical and Clinical Genetics, University of Helsinki, Helsinki, Finland.
  • Camilla Schalin-Jäntti
    3Endocrinology, Abdominal Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
  • Atte Karppinen
    4Department of Neurosurgery, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
  • Anders Paetau
    5Department of Pathology, HUSLAB, University of Helsinki, Helsinki, Finland.
  • Leena Kivipelto
    4Department of Neurosurgery, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
  • Lauri A. Aaltonen
    1Department of Medical and Clinical Genetics, University of Helsinki, Helsinki, Finland.
  • Auli Karhu
    1Department of Medical and Clinical Genetics, University of Helsinki, Helsinki, Finland.

抄録

<jats:title>Abstract</jats:title> <jats:sec> <jats:title /> <jats:p>Somatic driver mechanisms of pituitary adenoma pathogenesis have remained incompletely characterized; apart from mutations in the stimulatory Gα protein (Gαs encoded by GNAS) causing activated cAMP synthesis, pathogenic variants are rarely found in growth hormone–secreting pituitary tumors (somatotropinomas). The purpose of the current work was to clarify how genetic and epigenetic alterations contribute to the development of somatotropinomas by conducting an integrated copy number alteration, whole-genome and bisulfite sequencing, and transcriptome analysis of 21 tumors. Somatic mutation burden was low, but somatotropinomas formed two subtypes associated with distinct aneuploidy rates and unique transcription profiles. Tumors with recurrent chromosome aneuploidy (CA) were GNAS mutation negative (Gsp−). The chromosome stable (CS) –group contained Gsp+ somatotropinomas and two totally aneuploidy-free Gsp− tumors. Genes related to the mitotic G1–S-checkpoint transition were differentially expressed in CA- and CS-tumors, indicating difference in mitotic progression. Also, pituitary tumor transforming gene 1 (PTTG1), a regulator of sister chromatid segregation, showed abundant expression in CA-tumors. Moreover, somatotropinomas displayed distinct Gsp genotype–specific methylation profiles and expression quantitative methylation (eQTM) analysis revealed that inhibitory Gα (Gαi) signaling is activated in Gsp+ tumors. These findings suggest that aneuploidy through modulated driver pathways may be a causative mechanism for tumorigenesis in Gsp− somatotropinomas, whereas Gsp+ tumors with constitutively activated cAMP synthesis seem to be characterized by DNA methylation activated Gαi signaling.</jats:p> </jats:sec> <jats:sec> <jats:title>Implications:</jats:title> <jats:p>These findings provide valuable new information about subtype-specific pituitary tumorigenesis and may help to elucidate the mechanisms of aneuploidy also in other tumor types.</jats:p> </jats:sec>

収録刊行物

  • Molecular Cancer Research

    Molecular Cancer Research 17 (12), 2432-2443, 2019-12-01

    American Association for Cancer Research (AACR)

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