Related Experiment Video
Updated: Mar 27, 2026
Generation and Expansion of Primary, Malignant Pleural Mesothelioma Tumor Lines
Published on: April 21, 2022
Functional Analysis of the Adrenomedullin Pathway in Malignant Pleural Mesothelioma
Laurent Greillier1, Asma Tounsi2, Caroline Berenguer-Daizé2
1Aix-Marseille University, CRO2 UMR 911, Marseille, France; INSERM, CRO2 UMR 911, Marseille, France; Assistance Publique Hopitaux de Marseille, Service d'Oncologie Multidisciplinaire et Innovations Thérapeutiques, Marseille, France.
Introduction:
Malignant pleural mesothelioma (MPM) grows aggressively within the thoracic cavity and has a very low cure rate, thus highlighting the need for identification of new therapeutic targets. Adrenomedullin (AM) is a multifunctional peptide that is highly expressed in several tumors and plays an important role in angiogenesis and tumor growth after binding to its receptors, calcitonin receptor-like receptor/receptor activity-modifying protein 2 (CLR/RAMP2) and calcitonin receptor-like receptor/receptor activity-modifying protein 3 (CLR/RAMP3).
Methods:
Real time quantitative reverse transcriptase polymerase chain reaction (RT-PCR) was used to assess the steady-state levels of AM, CLR, RAMP2 and RAMP3 messenger RNA (mRNA) transcripts in normal pleural tissue (n=5) and MPM (n=24). The expression of these candidates at protein level was revealed by immunohistochemistry. We also characterized the expression and regulation by hypoxia of AM system in MPM cell lines and MeT-5A cells. In vitro and in vivo studies were performed to determine the functional role of AM system in MPM.
Results:
In this study, real-time quantitative reverse transcriptase polymerase chain reaction showed twofold to 10-fold higher levels of AM messenger RNA in MPM tissue than in normal pleural tissue. The MPM cell lines H2452, H2052, and human mesothelioma cell line MSTO-211H showed a significant increase in expression of AM messenger RNA under hypoxic conditions. Our results also show that AM stimulates cell proliferation in vitro through the Raf1 proto-oncogene, serine/threonine kinase (CRAF)/ Mitogen-activated protein kinase kinase 1 (MEK)/Extracellular regulated MAPKinase (ERK) pathway. Furthermore, the proliferation, migration, and invasion of MPM cells were decreased after treatment with anti-AM (αAM) and anti-AM receptor antibodies, thus indicating that MPM cells are regulated by AM. The action of AM was specific and mediated by CLR/RAMP2 and CLR/RAMP3 receptors. In vivo, αAM and AM22-52 antagonist therapies blocked angiogenesis and induced apoptosis in MSTO-211H xenografts, thereby resulting in tumor regression. Histologic examination of tumors treated with AM22-52 and αAM antibody showed evidence of disruption of tumor vasculature with depletion of vascular endothelial cells and a significant decrease in lymphatic endothelial cells.
Conclusions:
Our findings highlight the importance of the AM pathway in growth of MPM and in neovascularization by supplying and amplifying signals that are essential for pathologic neoangiogenesis and lymphangiogenesis.
Insights
Adrenomedullin (AM) drives malignant pleural mesothelioma (MPM) growth and new blood vessel formation. Blocking the AM pathway with antibodies or antagonists inhibits tumor progression and causes regression, offering a potential therapeutic strategy for MPM.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Malignant pleural mesothelioma (MPM) is an aggressive thoracic cancer with limited treatment options.
- Adrenomedullin (AM) is a peptide implicated in tumor growth and angiogenesis, acting via CLR/RAMP2 and CLR/RAMP3 receptors.
Purpose of the Study:
- To investigate the role of the Adrenomedullin (AM) pathway in the development and progression of Malignant Pleural Mesothelioma (MPM).
- To evaluate AM system components as potential therapeutic targets for MPM.
Main Methods:
- Quantitative reverse transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry to assess AM, CLR, RAMP2, and RAMP3 expression in MPM tissues and cell lines.
- In vitro and in vivo experiments using MPM cell lines and xenografts to study the functional role of AM and its receptors.
- Treatment with anti-AM (αAM) antibodies and AM22-52 antagonist to assess therapeutic efficacy.
Main Results:
- AM, CLR, RAMP2, and RAMP3 mRNA levels were significantly higher in MPM tissues compared to normal pleura.
- Hypoxia increased AM mRNA expression in MPM cell lines.
- AM promoted MPM cell proliferation, migration, and invasion via the CRAF/MEK/ERK pathway.
- Anti-AM therapies (αAM, AM22-52) inhibited angiogenesis, induced apoptosis, and caused tumor regression in vivo, with disruption of tumor vasculature.
Conclusions:
- The Adrenomedullin (AM) pathway is crucial for MPM growth, neovascularization, and lymphangiogenesis.
- Targeting the AM pathway presents a promising therapeutic strategy for Malignant Pleural Mesothelioma (MPM).
