Effects of Prolactin on TSC2-Null Eker Rat Cells and in Pulmonary Lymphangioleiomyomatosis

Abstract

Rationale: Lymphangioleiomyomatosis, a cystic lung disease of women, is characterized by proliferation of smooth muscle-like lymphangioleiomyomatosis cells, which possess mutations in the tuberous sclerosis complex genes, TSC1/TSC2. Growth factors involved in lymphangioleiomyomatosis cell proliferation are unknown. Prolactin, an important reproductive hormone in women, is known to promote cell proliferation and survival in other tissues. Objectives: To determine the role of prolactin in signaling and proliferation in lymphangioleiomyomatosis. Methods: Prolactin levels in the sera of patients with lymphangioleiomyomatosis were correlated with clinical status. Components of prolactin signal transduction pathways were assessed in lymphangioleiomyomatosis lesions from human lung explants by real-time reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry. Prolactin effects on proliferation and signaling were quantified in tuberin-deficient and tuberin-expressing rat cells in vitro. Measurements and Main Results: Higher prolactin levels in the sera of patients with lymphangioleiomyomatosis were associated with a faster rate of decline in FEV 1 and an increased history of pneumothorax (P , 0.01). Higher levels of prolactin and prolactin receptor mRNA and immunoreactivity were found in lymphangioleiomyomatosis lesions when compared with vascular smooth muscle cells in the same region of tissue. This was accompanied by evidence of activation of signal transducer and activator of transcription-1 (STAT1), STAT3, p44/42, and p38 mitogen-activated protein kinase. Tsc2 2/2 Eker rat embryonic fibroblasts expressed more prolactin receptor than did Tsc2 1/1 cells, and responded to prolactin with increased proliferation and activation of the same signaling pathways seen in vivo. Conclusions: Prolactin may be an important growth factor in the pathogenesis of lymphangioleiomyomatosis.Keywords: proliferation; pneumothorax; pulmonary function tests; tuberous sclerosis complex Lymphangioleiomyomatosis (LAM) is an uncommon disease, predominantly found in women of childbearing age and characterized by abnormal proliferation of smooth muscle-like LAM cells, causing cystic destruction of the lung, progressive loss of pulmonary function, and, in some patients, lung transplantation or death (1, 2). LAM occurs sporadically or in association with tuberous sclerosis complex (TSC), an autosomal dominant disorder of variable penetrance associated with hamartomatous lesions (3, 4). LAM cells from patients with sporadic LAM, as well as from patients with LAM with TSC, are associated with mutations in tuberous sclerosis genes, TSC1 or TSC2, that result in activation of the mammalian target of rapamycin (mTOR) signaling pathway, leading to dysregulation of cell proliferation, size, and survival (4-7).The reasons why pulmonary disease in LAM occurs predominantly in women are not well understood, but hormones such as estrogen or testosterone may play a role. Indeed, estrogen has been shown to promote tuberin-null cell survi...

Lymphangioleiomyomatosis — a wolf in sheep’s clothing

“…Regulation of the apoptotic potential of LAM cells is context-dependent and intimately related to met- abolic reprogramming and the nature of mitogenic stimuli. A variety of factors are likely to contribute to the proliferation of LAM cells, including β-catenin, which is activated in LAM (84)(85)(86), associated with upregulation of cyclin D1 (84), and contributes to LAM cell invasiveness (87); HMGA2, an architectural transcription factor that is misexpressed in a number of mesenchymal neoplasms (88); Polo-like kinase-1 (PLK1) (89) and PLK2 (90), which interact directly with TSC1 in a cell cycle-dependent manner; cyclin-dependent kinase inhibitor p27, which is mislocalized to the cytoplasm in TSC-deficient cells (91,92); and prolactin, a hormone and smooth muscle mitogen that is elevated in the serum of patients with LAM (93). A better understanding of these apoptotic and proliferative factors could lead to clearly targetable nodes.…”

Identification of the lymphangioleiomyomatosis cell and its uterine origin

“…A number of known LAM serum biomarkers were identified in the LAM CORE secretome including VEGFD (FIGF), MMP2, and CTSK (Ferri et al, 2004;Seyama et al, 2006). The expression of PRLR (prolactin receptor, also known as Secreted Prolactin Binding Protein), a newly predicted serum biomarker, is induced by ESR1 and PGR, and is capable of activating PI3K/AKT, ERK1/2 and TP53 signaling (Alkharusi et al, 2016;Terasaki et al, 2010). Genes encoding extracellular matrix associated proteins (i.e., collagen, glycosaminoglycans, proteoglycans, and endopeptidases) were the most enriched components in the LAM cell secretome and were associated with diverse LAM relevant functions including cell migration, angiogenesis, growth factor and estrogen responsiveness, and WNT, PI3K/AKT, P53 signaling pathways (Figure 4a).…”

“…may provide growth advantages to LAM cells. LAM CORE cells from LAM lungs expressed a unique panel of signature genes expressed in uterine LAM cells and in normal human and mouse uterus but not in normal human lung.LAM CORE cells and normal myometrial cells shared transcriptomic similarity which are regulated by female sex hormones, including estrogen, progesterone and prolactin receptorsTerasaki et al, 2010). scRNA-seq analysis of normal human and mouse uterine cells demonstrated a close relationship of LAM CORE signatures with uterine myocytes.…”

The prolactin receptor as a therapeutic target in human diseases: browsing new potential indications

“…[103] and references therein). A single recent study [104] suggested that PRL signaling could also promote LAM disease based on: i) the association of elevated PRL levels with disease progression in patients; ii) elevated PRL and PRLR expression (mRNA and immunoreactivity) in LAM lesions compared with vascular smooth muscle cells in the same region of the tissue; and iii) increased PRLR expression, activation of PRLR signaling pathways and PRL-induced proliferation of cells lacking tuberous sclerosis complex 2 gene.…”