Complexity of progranulin mechanisms of action in mesothelioma

Analysis of metastasis‑related risk factors and clinical relevance in adult soft‑tissue sarcoma

Metastasis occurs in nearly 50% of cases of adult soft-tissue sarcoma (ASTS), leading to a dismal prognosis, with a 2-year survival rate of ~30%. Consequently, a prognostic model that incorporates metastatic characteristics may be instrumental in predicting survival time and in crafting optimal personalized therapeutic strategies for patients with ASTS. In the present study, a prognostic prediction model for ASTS was developed by examining genes that are differentially expressed between non-metastatic and metastatic patients in the Gene Expression Omnibus dataset. The prognostic model, which includes five featured genes [actin γ2 (ACTG2), apolipoprotein D, coatomer protein complex subunit γ2 imprinted transcript 1, collagen type VI α6 chain and osteomodulin], was further validated in patients with ASTS from the Cancer Genome Atlas dataset. Based on these five-gene signatures, patients were categorized into high- and low-risk groups. Functional and pathway analyses revealed disparities in stemness, extracellular matrix and cell adhesion-related pathways between the two risk groups, particularly noting the activation of the PI3K-Akt pathway in high-risk cases. Analysis of immune infiltration also revealed variations in immune microenvironment changes between the two risk groups. Immunohistochemical staining substantiated the prognostic significance of these gene signatures in a specific sarcoma subtype. Additionally, wound-healing and Transwell assays demonstrated that inhibition of ACTG2 by shRNAs curbed cell migration and invasion in a sarcoma HOS cell line, underscoring its role in sarcoma metastasis. In conclusion, the present study successfully developed and validated a metastasis-based prognosis prediction model. This model not only reliably forecasts the survival of patients with ASTS, but also may pave the way for further investigation into the processes underlying sarcoma metastasis, ultimately aiding in the design of tailored therapeutic regimens.

Characterization of KLHL14 anti-oncogenic action in malignant mesothelioma

Malignant mesothelioma (MM) is a very aggressive neoplasia with a short life expectancy and limited therapeutic options. Thus, the identification of novel molecular targets is a matter of great urgency. Kelch-like (KLHL) proteins play an important role in a number of physiological and pathological cell-regulatory processes. Among this family, the function of KLHL14 is still very poorly characterized. KLHL14 was originally identified as a gene involved in regulating the epithelial-mesenchymal transition (EMT) process. Here, we demonstrate that KLHL14 not only prevents EMT but also plays an anti-oncogenic role in MM. Indeed, KLHL14 depletion enhanced proliferation, motility, invasion and colony formation in MM cells. Importantly, we also demonstrated that KLHL14 mechanism of action is dependent on Transforming Growth Factor β (TGF-β). In fact, TGF-β promotes de novo synthesis, increases protein stability and induces nuclear-cytoplasmic shuttling of KLHL14. Collectively, this research is an important step further to decipher KLHLs mechanism of action and further contributes to the understanding of the molecular mechanisms regulating MM.

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.

Orexins and Prostate Cancer: State of the Art and Potential Experimental and Therapeutic Perspectives

Prostate cancer (PCa) is the second most common cancer in humans. Peptides have recently been used as targeted therapeutics in cancers, due to their extensive multi-functional applications. Two hypothalamic peptides, orexins A (OXA) and B (OXB) and their specific receptors, orexin receptor 1 (OX1R) and 2 (OX2R), orchestrate several biological processes in the central nervous system and peripheral organs. However, in addition to their role in physiological responses, orexins are involved in numerous inflammatory and/or neoplastic pathologies. The presence and expression of orexins in different cancer models, including prostate cancer, and their role in inducing pro- or anti-apoptotic responses in tumor cell lines, suggest that the orexinergic system might have potential therapeutic action or function as a diagnostic marker in PCa. In addition to the traditional animal models for studying human PCa, the canine model might also serve as an additional tool, due to its clinical similarities with human prostate cancer.

Progranulin and EGFR modulate receptor-like tyrosine kinase sorting and stability in mesothelioma cells

Progranulin is a growth factor with pro-tumorigenic activity. We recently demonstrated that in mesothelioma, progranulin regulates cell migration, invasion, adhesion, and in vivo tumor formation by modulating a complex signaling network involving multiple receptor tyrosine kinase (RTK)s. Progranulin biological activity relies on epidermal growth factor receptor (EGFR) and receptor-like tyrosine kinase (RYK), a co-receptor of the Wnt signaling pathway, which are both required for progranulin-induced downstream signaling. However, the molecular mechanism regulating the functional interaction among progranulin, EGFR, and RYK are not known. In this study, we demonstrated that progranulin directly interacted with RYK by specific enzyme-linked immunosorbent assay (ELISA) (KD = 0.67). Using immunofluorescence and proximity ligation assay, we further discovered that progranulin and RYK colocalized in mesothelioma cells in distinct vesicular compartments. Notably, progranulin-dependent downstream signaling was sensitive to endocytosis inhibitors, suggesting that it could depend on RYK or EGFR internalization. We discovered that progranulin promoted RYK ubiquitination and endocytosis preferentially through caveolin-1-enriched pathways, and modulated RYK stability. Interestingly, we also showed that in mesothelioma cells, RYK complexes with the EGFR, contributing to the regulation of RYK stability. Collectively, our results suggest a complex regulation of RYK trafficking/activity in mesothelioma cells, a process that is concurrently regulated by exogenous soluble progranulin and EGFR. NEW & NOTEWORTHY The growth factor progranulin has pro-tumorigenic activity. In mesothelioma, progranulin signaling is mediated by EGFR and RYK, a co-receptor of the Wnt signaling. However, the molecular mechanisms regulating progranulin action are not well defined. Here, we demonstrated that progranulin binds RYK and regulates its ubiquitination, internalization, and trafficking. We also uncovered a role for EGFR in modulating RYK stability. Overall, these results highlight a complex modulation of RYK activity by progranulin and EGFR in mesothelioma.

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.