C1q-HA Matrix Regulates the Local Synthesis of Hyaluronan in Malignant Pleural Mesothelioma by Modulating HAS3 Expression.

Romana Vidergar,Marco Confalonieri,Fabrizio Zanconati,Beatrice Belmonte,Chiara Agostinis,Paola Zacchi,Francesco Salton,Micaela Grandolfo,Roberta Bulla,Alessandro Mangogna,Marco Biolo,Andrea Balduit

doi:10.3390/cancers13030416

Abstract

Simple SummaryMalignant pleural mesothelioma (MPM) is a rare and aggressive tumor characterized by poor prognosis due to late diagnosis and the absence of efficient first-line treatments. Hyaluronic acid (HA) and the complement protein C1q represent two pivotal players in the MPM tumor microenvironment by acting in association with effects on cancer cell adhesion, migration and proliferation. The aim of the current study is to prove HA production by MPM primary cells and to understand whether HA metabolism modulation could be considered a potential target for future therapeutic approaches in MPM.Increased hyaluronic acid (HA) production is often associated with cancer progression. In malignant pleural mesothelioma (MPM), HA is found at elevated levels in pleural effusions and sera of patients, and it has been widely debated whether MPM cells are able to produce HA by themselves or through the release of growth factors stimulating other cells. Another key component of the MPM microenvironment is C1q, which can act as a pro-tumorigenic factor favoring cell adhesion, migration and proliferation. The aim of the current study was to prove that MPM primary cells are able to synthesize HA and to inquire the stimulus given by C1q–HA matrix to HA synthesis. We confirmed the presence of a HA coat and cable-like structures around MPM primary cells, as well as an intracellular pool, mainly localized in the cytoplasmic and perinuclear region. After evaluating HA synthase (HAS) enzymes’ basal expression in MPM primary cells, we found that C1q bound to HA was able to impinge upon HA homeostasis by upregulating HAS3 both at the mRNA and the protein levels. High expression of HAS3 has been correlated with a shorter life expectancy in MPM by bioinformatical analysis. These data confirmed that C1q bound to HA may exert pro-tumorigenic activity and identified HAS3 as a potential target in MPM.

Highlights

Malignant pleural mesothelioma (MPM) is a rare and aggressive kind of cancer arising from the mesothelial cells of the pleura
We initially aimed at investigating hyaluronic acid (HA) presence in the malignant pleural mesothelioma (MPM) tumor microenvironment by histochemical analysis of paraffin-embedded MPM tissue samples stained with the Alcian blue solution, a cationic dye used for the detection of acidic glycosaminoglycans
Histochemical staining with Alcian Blue highlighted HA distribution in MPM tissue sections; in particular, the staining was visible in tumor-associated stroma

Summary

Introduction

Malignant pleural mesothelioma (MPM) is a rare and aggressive kind of cancer arising from the mesothelial cells of the pleura. The unique MPM tumor microenvironment, in addition to genetic abnormalities accumulating in mesothelial cells, is responsible for tumor capacities of migration, invasion and metastasis [3,4]. Within this context, the extracellular matrix (ECM) and in particular one of its components, hyaluronic acid (HA), plays a pivotal role in MPM progression [5,6]. HA synthesis, unlike of other GAGs, occurs in the plasma membrane and hyaluronan synthases (HAS1, HAS2 and HAS3) are the integral membrane proteins responsible for its production, showing different enzymatic activity [8,9]. HA synthase enzymes are glycosyltransferases exerting their catalytic activity on the inner side of plasma membrane, where they synthetize large and linear polymers of the repeating disaccharide structure of hyaluronan by adding alternately the two precursors, uridine diphosphate (UDP)-N-acetylglucosamine and UDP-glucuronic acid, to the reducing terminus of the chain [10]

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