Complement protein C1q stimulates hyaluronic acid degradation via gC1qR/HABP1/p32 in malignant pleural mesothelioma

Our plain-English summary of Complement protein C1q stimulates hyaluronic acid degradation via gC1qR/HABP1/p32 in malignant pleural mesothelioma, by A. Balduit, R. Vidergar, P. Zacchi, et al (Frontiers in Immunology, 2023).

The study

• Authors: A. Balduit, R. Vidergar, P. Zacchi, A. Mangogna, C. Agostinis, M. Grandolfo, C. Bottin, F. Salton, P. Confalonieri, A. Rocca, F. Zanconati, M. Confalonieri, U. Kishore, B. Ghebrehiwet, R. Bulla
• Journal: Frontiers in Immunology
• Published: 2023;14:1151194
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Complement component C1q can act as a pro-tumorigenic factor in the tumor microenvironment (TME). The TME in malignant pleural mesothelioma (MPM) is rich in C1q and hyaluronic acid (HA), whose interaction enhances adhesion, migration and proliferation of malignant cells. HA-bound C1q is also capable of modulating HA synthesis. Thus, we investigated whether HA-C1q interaction would affect HA degradation, analyzing the main degradation enzymes, hyaluronidase (HYAL)1 and HYAL2, and a C1q receptor candidate. We first proceeded with the characterization of HYALs in MPM cells, especially HYAL2, since bioinformatics survival analysis revealed that higher HYAL2 mRNA levels have an unfavorable prognostic index in MPM patients. Interestingly, Real-Time quantitative PCR, flow cytometry and Western blot highlighted an upregulation of HYAL2 after seeding of primary MPM cells onto HA-bound C1q. In an attempt to unveil the receptors potentially involved in HA-C1q signaling, a striking co-localization between HYAL2 and globular C1q receptor/HABP1/p32 (gC1qR) was found by immunofluorescence, surface biotinylation and proximity ligation assays. RNA interference experiments revealed a potentially regulatory function exerted by gC1qR on HYAL2 expression, since C1QBP (gene for gC1qR) silencing unexpectedly caused HYAL2 downregulation. In addition, the functional blockage of gC1qR by a specific antibody hindered HA-C1q signaling and prevented HYAL2 upregulation. Thus, C1q-HA interplay is responsible for enhanced HYAL2 expression, suggesting an increased rate of HA catabolism and the release of pro-inflammatory and pro-tumorigenic HA fragments in the MPM TME. Our data support the notion of an overall tumor-promoting property of C1q. Moreover, the overlapping localization and physical interaction between HYAL2 and gC1qR suggests a potential regulatory effect of gC1qR within a putative HA-C1q macromolecular complex.

Copyright © 2023 Balduit, Vidergar, Zacchi, Mangogna, Agostinis, Grandolfo, Bottin, Salton, Confalonieri, Rocca, Zanconati, Confalonieri, Kishore, Ghebrehiwet and Bulla.

In plain English

This laboratory study examined tumor cells from malignant pleural mesothelioma, a cancer of the lining around the lungs. Cells came from pleural biopsies of ten male patients in Trieste, Italy, who had a history of asbestos exposure. Asbestos itself was not tested. Two mesothelioma cell lines were also used. The authors asked whether C1q, an immune-system protein, bound to hyaluronic acid (a substance around cells) changes the enzymes that break hyaluronic acid down. These enzymes were active in the cells. In public data from 82 patients, higher HYAL2 gene expression (mRNA) was linked to shorter overall survival (hazard ratio 2.2, p = 0.0023). No statistically significant link was found for HYAL1. Cells grown on hyaluronic acid with C1q made more HYAL2 than cells grown on hyaluronic acid alone, and moved more of it to the cell surface. HYAL2 sat close to a C1q receptor called gC1qR. Silencing the receptor's gene lowered HYAL2, and blocking the receptor with an antibody prevented the C1q-driven HYAL2 increase. The authors concluded their data are consistent with a tumor-promoting activity of C1q, together with hyaluronic acid.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory (in vitro) study of primary mesothelioma cells and cell lines, with a bioinformatics survival analysis of public gene-expression data
• Who was studied: Ten patients with malignant pleural mesothelioma enrolled at the University Hospital of Cattinara, Trieste, Italy. All were male and Caucasian, all had the epithelioid type, and none had received chemotherapy or radiotherapy before biopsy. Mean age at diagnosis was 74.2 plus or minus 6.0 years. The study also used the human mesothelioma cell lines H28 and ZL34, and survival data on 82 patients from the TCGA-MESO dataset. Study dates are not given.
• Exposure: In the laboratory, cells were exposed to hyaluronic acid with or without the complement protein C1q, either dissolved in the medium or coated onto plates as a matrix. The patients had a history of asbestos exposure, but asbestos and fiber types were not studied.
• Main results:
  • Hyaluronidase enzymes (HYALs) were active in the mesothelioma cells.
  • In the 82 TCGA-MESO patients, high HYAL2 mRNA expression was associated with lower survival (hazard ratio 2.2; p = 0.0023).
  • In the same analysis, no significant correlation was found between HYAL1 mRNA expression and survival.
  • Soluble hyaluronic acid and/or C1q did not change HYAL gene activity in the primary mesothelioma cells.
  • Compared with hyaluronic acid alone, the hyaluronic acid plus C1q matrix increased HYAL2 at the protein level. Protein assays did not confirm a significant HYAL1 decrease.
  • The hyaluronic acid plus C1q matrix increased the amount of HYAL2 moved to the cell membrane.
  • HYAL2 was found in the same locations as the C1q receptor gC1qR in mesothelioma cells.
  • Proximity assays detected interactions among HYAL2, gC1qR and CD44, which the authors took to suggest a three-protein complex.
  • In mesothelioma cell lines, silencing the gC1qR gene (C1QBP) lowered HYAL2 expression, while silencing CD44 did not.
  • In H28 cells, blocking gC1qR with an antibody prevented the increase in HYAL2 seen on the hyaluronic acid plus C1q matrix.
  • Small fragments of hyaluronic acid (LMW-HA) triggered production of reactive oxygen species by the mesothelioma cells. Large hyaluronic acid (HMW-HA) and C1q alone did not.
• The authors' conclusion: The authors concluded that hyaluronic-acid-bound C1q increases HYAL2 in mesothelioma cells, and that the data are consistent with a tumor-promoting activity of C1q, together with hyaluronic acid. They suggested that gC1qR may be involved in this signaling.
• Limitations the authors state:
  • The enzyme-activity assay could not separate the contributions of HYAL1 and HYAL2.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Hyaluronic Acid, Pleural Mesothelioma, Tumor Microenvironment.

Related studies

• Complement Protein C1q Binds to Hyaluronic Acid in the Malignant Pleural Mesothelioma Microenvironment and Promotes Tumor Growth — C. Agostinis, R. Vidergar, et al. (2017)
• Prognostic Implications of the Complement Protein C1q in Gliomas — A. Mangogna, B. Belmonte, et al. (2019)
• Serum mesothelin has a higher diagnostic utility than hyaluronic acid in malignant mesothelioma — B. Grigoriu, B. Chahine, et al. (2009)
• Histochemical demonstration of hyaluronic acid in pleural mesotheliomas — J.C. Wagner, D.E. Munday, et al. (1962)
• Pleural effusion hyaluronic acid as a prognostic marker in pleural malignant mesothelioma — J. Creaney, I.M. Dick, et al. (2013)
• Hyaluronic acid in the pleural fluid of patients with malignant pleural mesothelioma — N. Fujimoto, K. Gemba, et al. (2013)

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