Progranulin depletion inhibits proliferation via the transforming growth factor beta/SMAD family member 2 signaling axis in Kasumi-1 cells

Progranulin: A promising biomarker and therapeutic target for fibrotic diseases

Progranulin (PGRN), a multifunctional growth factor-like protein expressed by a variety of cell types, serves an important function in the physiologic and pathologic processes of fibrotic diseases, including wound healing and the inflammatory response. PGRN was discovered to inhibit pro-inflammation effect by competing with tumor necrosis factor-alpha (TNF-α) binding to TNF receptors. Notably, excessive tissue repair in the development of inflammation causes tissue fibrosis. Previous investigations have indicated the significance of PGRN in regulating inflammatory responses. Recently, multiple studies have shown that PGRN was linked to fibrogenesis, and was considered to monitor the formation of fibrosis in multiple organs, including liver, cardiovascular, lung and skin. This paper is a comprehensive review summarizing our current knowledge of PGRN, from its discovery to the role in fibrosis. This is followed by an in-depth look at the characteristics of PGRN, consisting of its structure, basic function and intracellular signaling. Finally, we will discuss the potential of PGRN in the diagnosis and treatment of fibrosis.

The Role of Progranulin (PGRN) in the Pathogenesis of Glioblastoma Multiforme

Glioblastoma multiforme (GBM) represents the most common and aggressive malignant form of brain tumour in adults and is characterized by an extremely poor prognosis with dismal survival rates. Currently, expanding concepts concerning the pathophysiology of GBM are inextricably linked with neuroinflammatory phenomena. On account of this fact, the identification of novel pathomechanisms targeting neuroinflammation seems to be crucial in terms of yielding successful individual therapeutic strategies. In recent years, the pleiotropic growth factor progranulin (PGRN) has attracted significant attention in the neuroscience and oncological community regarding its neuroimmunomodulatory and oncogenic functions. This review of the literature summarizes and updates contemporary knowledge about PGRN, its associated receptors and signalling pathway involvement in GBM pathogenesis, indicating possible cellular and molecular mechanisms with potential diagnostic, prognostic and therapeutic targets in order to yield successful individual therapeutic strategies. After a review of the literature, we found that there are possible PGRN-targeted therapeutic approaches for implementation in GBM treatment algorithms both in preclinical and future clinical studies. Furthermore, PGRN-targeted therapies exerted their highest efficacy in combination with other established chemotherapeutic agents, such as temozolomide. The results of the analysis suggested that the possible implementation of routine determinations of PGRN and its associated receptors in tumour tissue and biofluids could serve as a diagnostic and prognostic biomarker of GBM. Furthermore, promising preclinical applications of PGRN-related findings should be investigated in clinical studies in order to create new diagnostic and therapeutic algorithms for GBM treatment.

Progranulin and GPNMB: interactions in endo-lysosome function and inflammation in neurodegenerative disease

BACKGROUND

Alterations in progranulin (PGRN) expression are associated with multiple neurodegenerative diseases (NDs), including frontotemporal dementia (FTD), Alzheimer's disease (AD), Parkinson's disease (PD), and lysosomal storage disorders (LSDs). Recently, the loss of PGRN was shown to result in endo-lysosomal system dysfunction and an age-dependent increase in the expression of another protein associated with NDs, glycoprotein non-metastatic B (GPNMB).

MAIN BODY

It is unclear what role GPNMB plays in the context of PGRN insufficiency and how they interact and contribute to the development or progression of NDs. This review focuses on the interplay between these two critical proteins within the context of endo-lysosomal health, immune function, and inflammation in their contribution to NDs.

SHORT CONCLUSION

PGRN and GPNMB are interrelated proteins that regulate disease-relevant processes and may have value as therapeutic targets to delay disease progression or extend therapeutic windows.

Progranulin Oncogenic Network in Solid Tumors

Progranulin is a pleiotropic growth factor with important physiological roles in embryogenesis and maintenance of adult tissue homeostasis. While-progranulin deficiency is associated with a broad range of pathological conditions affecting the brain, such as frontotemporal dementia and neuronal ceroid lipofuscinosis, progranulin upregulation characterizes many tumors, including brain tumors, multiple myeloma, leiomyosarcoma, mesothelioma and epithelial cancers such as ovarian, liver, breast, bladder, adrenal, prostate and kidney carcinomas. The increase of progranulin levels in tumors might have diagnostic and prognostic significance. In cancer, progranulin has a pro-tumorigenic role by promoting cancer cell proliferation, migration, invasiveness, anchorage-independent growth and resistance to chemotherapy. In addition, progranulin regulates the tumor microenvironment, affects the function of cancer-associated fibroblasts, and modulates tumor immune surveillance. However, the molecular mechanisms of progranulin oncogenic function are not fully elucidated. In bladder cancer, progranulin action relies on the activation of its functional signaling receptor EphA2. Notably, more recent data suggest that progranulin can also modulate a functional crosstalk between multiple receptor-tyrosine kinases, demonstrating a more complex and context-dependent role of progranulin in cancer. Here, we will review what is currently known about the function of progranulin in tumors, with a focus on its molecular mechanisms of action and regulation.

Helicobacter pylori-Induced Progranulin Promotes the Progression of the Gastric Epithelial Cell Cycle by Regulating CDK4

Helicobacter pylori, a group 1 carcinogen, colonizes the stomach and affects the development of stomach diseases. Progranulin (PGRN) is an autocrine growth factor that regulates multiple cellular processes and plays a tumorigenic role in many tissues. Nevertheless, the mechanism of action of PGRN in gastric cancer caused by H. pylori infection remains unclear. Here, we investigated the role of PGRN in cell cycle progression and the cell proliferation induced by H. pylori infection. We found that the increased PGRN was positively associated with CDK4 expression in gastric cancer tissue. PGRN was upregulated by H. pylori infection, thereby promoting cell proliferation, and that enhanced level of proliferation was reduced by PGRN inhibitor. CDK4, a target gene of PGRN, is a cyclin-dependent kinase that binds to cyclin D to promote cell cycle progression, which was upregulated by H. pylori infection. We also showed that knockdown of CDK4 reduced the higher cell cycle progression caused by upregulated PGRN. Moreover, when the PI3K/Akt signaling pathway (which is promoted by PGRN) was blocked, the upregulation of CDK4 mediated by PGRN was reduced. These results reveal the potential mechanism by which PGRN plays a major role through CDK4 in the pathological mechanism of H. pylori infection.