Pemetrexed-loaded nanoparticles targeted to malignant pleural mesothelioma cells: an in vitro study

Our plain-English summary of Pemetrexed-loaded nanoparticles targeted to malignant pleural mesothelioma cells: an in vitro study, by E. Cova, L. Pandolfi, M. Colombo, et al (International Journal of Nanomedicine, 2019).

The study

• Authors: E. Cova, L. Pandolfi, M. Colombo, V. Frangipane, S. Inghilleri, M. Morosini, S. Mrakic-Sposta, S. Moretti, M. Monti, Y. Pignochino, S. Benvenuti, D. Prosperi, G. Stella, P. Morbini, F. Meloni
• Journal: International Journal of Nanomedicine
• Published: 2019;14:773-785
• Cited by: 18 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Purpose: Malignant pleural mesothelioma (MPM) is an aggressive tumor characterized by poor prognosis. Its incidence is steadily increasing due to widespread asbestos exposure. There is still no effective therapy for MPM. Pemetrexed (Pe) is one of the few chemotherapeutic agents approved for advanced-stage disease, although the objective response to the drug is limited. The use of gold nanoparticles (GNPs) as a drug delivery system promises several advantages, including specific targeting of malignant cells, with increased intracellular drug accumulation and reduced systemic toxicity, and, in the case of MPM, direct treatment administration into the pleural space. This study aims at exploring CD146 as a potential MPM cell-specific target for engineered Pe-loaded GNPs and to assess their effectiveness in inhibiting MPM cell line growth.

Methods: MPM cell lines and primary cultures obtained by pleural effusions from MPM patients were assayed for CD146 expression by flow cytometry. Internalization by MPM cell lines of fluorescent dye-marked GNPs decorated with a monoclonal anti CD146 coated GNPs (GNP-HC) was proven by confocal microscopy. The effects of anti CD146 coated GNPs loaded with Pe (GNP-HCPe) on MPM cell lines were evaluated by cell cycle (flow cytometry), viability (MTT test), clonogenic capacity (soft agar assay), ROS production (electric paramagnetic resonance), motility (wound healing assay), and apoptosis (flow cytometry).

Results: GNP-HC were selectively uptaken by MPM cells within 1 hour. MPM cell lines were blocked in the S cell cycle phase in the presence of GNP-HCPe. Both cell viability and motility were significantly affected by nanoparticle treatment compared to Pe. Apoptotic rate and ROS production were significantly higher in the presence of nanoparticles. Clonogenic capacity was completely inhibited following nanoparticle internalization.

Conclusion: GNP-HCPe treatment displays in vitro antineoplastic action and is more effective than Pe alone in inhibiting MPM cell line malignant phenotype. The innovative use of specifically targeted GNPs opens the perspective of local intrapleural administration to avoid normal cell toxicity and enhance chemotherapy efficacy.

In plain English

This was a laboratory (in vitro) study by researchers in Italy. It tested a new way to deliver the chemotherapy drug pemetrexed to malignant pleural mesothelioma cells. The drug was attached to tiny gold particles coated with an antibody against CD146, a protein on the surface of mesothelioma cells. CD146 was found on 96.97% of cells grown from patients' pleural fluid and on 99.9% and 94.4% of two commercial mesothelioma cell lines. In tissue samples, tumor cells carried CD146 and reactive mesothelial cells did not. The coated particles entered mesothelioma cells within 2 hours but did not enter lung cancer cells lacking CD146. In the two cell lines, the drug-loaded particles cut viability to 65.6% and 64.3% of untreated cells at 24 hours, and to 65.7% and 59.4% at 96 hours, with wide variation. The effect peaked at 72 hours. The particles raised cell death more than the same pemetrexed dose alone. They also completely stopped colony growth, which pemetrexed alone did not reduce. Both treatments slowed cell movement. The authors called the work a preliminary proof of concept that needs animal studies. No people or animals were treated, and asbestos exposure was not studied.

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) experiment on cultured mesothelioma cells, which the authors describe as a preliminary proof-of-concept
• Who was studied: Two commercial human malignant pleural mesothelioma cell lines: MSTO-211H (biphasic) and NCI-H2452 (epithelioid). Also primary cells isolated from pleural exudates of MPM patients at IRCCS Policlinico San Matteo, Pavia, Italy (number of patients not stated), and archival MPM biopsies. A549 adenocarcinoma cells, which lack CD146, were used as a comparison. The nanoparticle experiments were done only on the two commercial cell lines.
• Exposure: Asbestos exposure was not studied. The cells were treated in three ways: gold nanoparticles coated with anti-CD146 antibody and loaded with pemetrexed (GNP-HCPe; 25 µg/mL of nanoparticles and 100 nM pemetrexed); pemetrexed alone at 100 nM; or culture medium only as a control.
• Main results:
  • CD146 was expressed by 96.97% (plus or minus 2.0%) of primary MPM cells, by 99.9% (plus or minus 1.8%) of MSTO-211H cells, and by 94.4% (plus or minus 1.3%) of NCI-H2452 cells.
  • In MPM biopsies, tumor cells expressed CD146 on the cell membrane, while reactive mesothelial cells were negative.
  • The antibody-coated nanoparticles were taken up by MPM cells within 2 hours. CD146-negative A549 cells showed no uptake, and nanoparticles without the antibody were not internalized.
  • At 24 hours after treatment with drug-loaded nanoparticles, viability was 65.6% (plus or minus 21.4%) in MSTO-211H cells and 64.3% (plus or minus 6.4%) in NCI-H2452 cells, compared with 100% in untreated cells.
  • At 96 hours, viability with drug-loaded nanoparticles was 65.7% (plus or minus 16.3%) in MSTO-211H cells and 59.4% (plus or minus 15.5%) in NCI-H2452 cells.
  • For both cell lines, the greatest reduction in viability with drug-loaded nanoparticles was recorded at 72 hours. The 72-hour values are shown only in a figure that is unreadable in this text.
  • Pemetrexed alone at the same concentration produced only a modestly significant reduction in viability: about 20% at 48 hours in MSTO-211H cells and about 10% at 72 hours in NCI-H2452 cells.
  • In both cell lines, drug-loaded nanoparticles significantly increased the rate of apoptosis (programmed cell death) compared with pemetrexed alone.
  • In MSTO-211H cells, drug-loaded nanoparticles caused more cells than pemetrexed alone to accumulate in the S phase of the cell cycle at 24 hours, followed by accumulation in the G2/M phase at 48 hours.
  • Both treatments increased reactive oxygen species (ROS) production. The drug-loaded nanoparticles were more effective, and their effect lasted longer than that of pemetrexed alone.
  • Drug-loaded nanoparticles completely inhibited colony growth in soft agar. Colony counts with pemetrexed alone were 139 (plus or minus 25) in MSTO-211H and 619 (plus or minus 72) in NCI-H2452. Counts in untreated cells were 142 (plus or minus 20) and 874 (plus or minus 42), respectively. The authors stated that pemetrexed alone did not reduce colony formation.
  • Both drug-loaded nanoparticles and pemetrexed alone significantly reduced cell migration compared with untreated cells. The authors stated that for motility, the nanoparticles were as effective as the drug alone.
• The authors' conclusion: The authors concluded that their targeted nanoparticles impaired the malignant behavior of mesothelioma cells in the laboratory. They believe this is a promising approach for developing a local treatment for MPM.
• Limitations the authors state:
  • The authors describe the study as a preliminary proof-of-concept that needs more extensive studies and experiments in animal models.
  • The two cell lines responded at different rates. The authors say this suggests individual variability whose causes still need to be explored.

Topics

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

Medical terms in this study, explained in our Lexicon: Pemetrexed (Alimta), Pleural Mesothelioma, Prognosis, Asbestos Exposure, Pleural Effusion, Monoclonal, Apoptosis, Chemotherapy.

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