Identification of novel COX-2 / CYP19A1 axis involved in the mesothelioma pathogenesis opens new therapeutic opportunities

Our plain-English summary of Identification of novel COX-2 / CYP19A1 axis involved in the mesothelioma pathogenesis opens new therapeutic opportunities, by B. Nuvoli, B. Antoniani, R. Libener, et al (Journal of Experimental & Clinical Cancer Research, 2021).

The study

• Authors: B. Nuvoli, B. Antoniani, R. Libener, A. Maconi, A. Sacconi, M. Carosi, R. Galati
• Journal: Journal of Experimental & Clinical Cancer Research
• Published: 2021;40(1):257
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Based on previous studies highlighting that the induction of cyclooxygenase-2 (COX-2) and high prostaglandin E2 (PGE2) levels contribute to the pathogenesis of malignant pleural mesothelioma (MPM), and that aromatase (CYP19A1), an enzyme that plays a key role in estrogen biosynthesis, along with estradiol (E2) were expressed in MPM, this study aimed to investigate the possible interplay between COX-2 and CYP19A1 in the pathogenesis of mesothelioma, as well as the underlying mechanism.

Methods: The interaction between COX-2 and CYP19A1 was first investigated on different MPM lines upon PGE2, and COX-2 inhibitor (rofecoxib) treatment by western blot, RT-PCR. The key regulatory pathways involved in the COX-2 and CYP19A1 axis were further studied in MPM cells, after rofecoxib and exemestane (CYP19A1 inhibitor) treatment in monotherapy and in combination, by cell cycle distribution, western blot, and combination index analysis. To explore the role of COX-2/CYP19A1 axis in 3D preclinical models of MPM cells, we analyzed the effect of combination of COX-2 and CYP19A1 inhibitors in mesosphere formation. Immunohistochemical analysis of MPM mesosphere and specimens was utilized to evaluate the involvement of COX-2 on the CYP19A1 activity and the relationship between E2 and COX-2.

Results: PGE2 or rofecoxib treatment caused in MPM cells an increased or decreased, respectively, CYP19A1 expression at mRNA and protein levels. The effect of rofecoxib and exemestane combination in MPM cell proliferation was synergistic. Activation of caspase-3 and cleavage of PARP confirmed an apoptotic death for MPM cell lines. Increased expression levels of p53, p21, and p27, downregulation of cyclin D1 and inhibition of Akt activation (pAKT) were also found. The antagonistic effect of rofecoxib and exemestane combination found only in one cell line, was reverted by pretreatment with MK2206, a pAKT inhibitor, indicating pAKT as an actionable mediator in the COX-2-CYP19A1 axis. Reduction of size and sphere-forming efficiency in MPM spheres after treatment with both inhibitor and a decrease in COX-2 and E2 staining was found. Moreover, immunohistochemical analysis of 46 MPM samples showed a significant positive correlation between COX-2 and E2.

Conclusions: Collectively, the results highlighted a novel COX-2/CYP19A1 axis in the pathogenesis of MPM that can be pharmacologically targeted, consequently opening up new therapeutic options.

© 2021. The Author(s).

In plain English

This was a laboratory study, not a study of asbestos-exposed people. The authors studied two enzymes in human malignant pleural mesothelioma (MPM) cell lines and tumor samples: COX-2, linked to inflammation, and aromatase (CYP19A1), which makes estradiol (E2). In five cell lines, the messenger RNA levels of the two enzymes rose and fell together (r = 0.83). Adding prostaglandin E2 raised aromatase mRNA, and the COX-2 inhibitor rofecoxib lowered it. Rofecoxib combined with the aromatase inhibitor exemestane for 48 hours left 44% of Ist Mes1 cells alive compared with untreated cells. The combination was strongly synergistic in Ist Mes1 cells, moderately synergistic in MPP89 cells and antagonistic in Ist Mes2 cells. In Ist Mes2 cells pretreated with the AKT inhibitor MK2206, live cells after 24 hours of the combination were 46% of untreated cells. The drugs reduced the formation and size of three-dimensional tumor spheres. Tumor tissue from 46 patients was stained, with scores reported for 45. COX-2 and E2 staining were correlated (R = 0.35, p = 0.017). The authors concluded that a COX-2/CYP19A1 axis in MPM could be targeted with drugs. They called for future in vivo studies.

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 human mesothelioma cell lines and 3D spheroids, with immunohistochemical analysis of archival tumor tissue samples
• Who was studied: Five human pleural MPM cell lines (MSTO-211 H, NCIH-2452, Ist-Mes1, Ist-Mes2, MPP89). Tumor tissue from 46 MPM patients (31 male, 15 female, aged 45 to 80) and 3 normal control subjects, from the Mesothelioma Biobank in Alessandria, Italy. Staining-score categories were reported for 45 tumor tissues. The authors also reanalysed data on 29 MPM specimens from their earlier studies.
• Exposure: No asbestos exposure was studied. Cells were treated with 10 nM prostaglandin E2, 35 µM rofecoxib (a COX-2 inhibitor), 35 µM exemestane (a CYP19A1 inhibitor), or the two drugs combined. Ist Mes2 cells were also pretreated with the AKT inhibitor MK2206.
• Main results:
  • In the reanalysis of 29 MPM specimens, COX-2 staining was positively correlated with CYP19A1 staining (r = 0.9091)
  • COX-2 and CYP19A1 mRNA levels were positively correlated across the five MPM cell lines (r = 0.83, p = 0.0001)
  • In MPM cells, prostaglandin E2 significantly increased CYP19A1 mRNA three hours after it was added
  • Rofecoxib decreased CYP19A1 mRNA in MPM cells compared with untreated cells
  • After 48 h, the rofecoxib plus exemestane combination left 44% live Ist Mes1 cells compared with untreated cells
  • The combination index at 48 h showed a strongly synergistic effect in Ist Mes1 cells, a moderately synergistic effect in MPP89 cells and an antagonistic effect in Ist Mes2 cells
  • In Ist Mes1 and MPP89 cells, the combination increased cleaved PARP, reduced caspase-3 and cyclin D1, and increased p21, p27 and (in Ist Mes1 only) p53. The authors interpreted this as apoptosis and cell-cycle disruption.
  • Ist Mes2 cells were pre-incubated with MK2206 and then treated for 24 h. Live cells, compared with untreated cells (100%), were 55% after exemestane, 59% after rofecoxib and 46% after the combination.
  • Either inhibitor alone or both together reduced sphere-forming efficiency and sphere size, especially in Ist Mes1 and MPP89 cells
  • In MPP89 spheres, COX-2 and E2 staining fell after treatment with either drug or the combination
  • Of the 45 tumor tissues with reported staining scores, 28 (62%) had the same score category for E2 and COX-2
  • COX-2 and E2 staining in the MPM tissue samples were associated (Fisher's exact test P = 0.0003) and correlated (Spearman R = 0.35, p = 0.017)
• The authors' conclusion: The authors concluded that their results highlighted a novel COX-2/CYP19A1 axis in the pathogenesis of MPM that can be targeted with drugs, opening up new therapeutic options
• Limitations the authors state:
  • After drug treatment, the Ist Mes1 and Ist Mes2 spheres did not give enough material for immunohistochemistry, so only MPP89 spheres could be analysed
  • The authors stated that future in vivo studies of the rofecoxib and exemestane combination are needed

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, PGE2, Pleural Mesothelioma.

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