ESPE Abstracts

Background and Aim: Germline mutations in the tumor suppressor gene PTEN cause PTEN Hamartoma Tumor Syndrome (PHTS). Pediatric patients frequently develop lipomas. PTEN antagonizes the growth promoting PI3K/AKT/mTOR pathway. There is no current treatment option except surgery. Treatment attempts with the mTORC1 inhibitor Rapamycin could not reverse lipoma growth. Recently, lipomas associated with a related syndrome caused by mosaic activating PI3K mutations (P...

Background and Aim: Pediatric patients with germline mutations in the tumor suppressor gene PTEN (PTEN hamartoma tumor syndrome, PHTS) frequently develop lipomas. PTEN antagonizes phosphoinositide 3-kinase (PI3K) signaling, which can induce adipogenesis upon activation through insulin. The PI3K downstream target AKT can deactivate FOXO1 via phosphorylation, initiating the expression of the lipogenesis activating transcription factor SREBP1. To study t...

Background: Pediatric patients with germline pathogenic variants in the tumor suppressor gene PTEN frequently develop cancer and adipose tissue overgrowth in the form of lipomas. While the canonical function of the phosphatase PTEN is to antagonize the growth promoting PI3K pathway, non-canonical PTEN functions e.g. in the nucleus are less well described. To uncover the mechanisms leading to lipoma formation related to PTEN mutations, we previously performed R...

Background/aim: The PTEN hamartoma tumor syndrome (PHTS) is an overgrowth syndrome caused mainly by germline mutations in the tumor suppressor PTEN. Patients are predisposed for the development of malignant and benign tumors. Children and adolescents with PHTS frequently develop single or multiple lipomas. PTEN antagonizes the phosphatidylinositide3-kinase/AKT/mechanistic target of rapamycin (PI3K/AKT/mTOR) pathway, which promotes proliferation and differentiation in ...

Introduction: Leptin, an adipokine secreted mainly by adipose tissue, is a regulator of energy balance acting through central mechanisms on the hypothalamus. However, leptin has many functions regulating e.g., immune system and reproduction. Leptin exerts its biological effects through its receptor, the expression of which has been demonstrated in several tissues. There are several leptin receptor isoforms, but activation of only one of them, the long form, re...

Background and aim: PTEN hamartoma tumor syndrome (PHTS) is caused by germline mutation in the phosphatase and tensin homolog (PTEN) gene. PTEN is a tumor suppressor gene and antagonist of the growth and survival signalling Phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of Rapamycin (mTOR)- cascade. Patients with PHTS, amongst other symptoms, develop lipomas, for which the underlying mechanism is not completely understood. To investigate the role of PTE...

Background: Bone development and remodeling are controlled by the phosphoinositid-3-kinase (PI3K) signaling pathway. We investigated the effects of downregulation of phosphatase and tensin homolog (Pten), a negative regulator of PI3K signaling, in osteoprogenitor cells.Methods: Femura, tibiae and bone marrow stromal cells (BMSCs) from mice with Cre-inducible Pten knockdown in cells expressing the transcription factor Ost...

Background: Signaling through the phosphoinositid-3-kinase (PI3K) pathway modulates bone development and remodeling. We aimed to dissect the role of phosphatase and tensin homolog (Pten), a negative regulator of PI3K signaling, in osteoprogenitor cells.Methods: Femura, tibiae and bone marrow stromal cells (BMSCs) from mice with Cre-inducible Pten knockdown in cells expressing the transcription factor Osterix (Pten cKO) a...

Obesity presents a major worldwide challenge, due to its numerous, severe adverse effects on health. This leads to a necessity to further investigate the mechanisms underlying lipid accumulation. The adipocytokine leptin may contribute to this process. While there already has been thorough research into central leptin action, deepening our understanding of leptin’s effects on whole-body energy homeostasis, relatively little is known about its auto- and paracrine effects....