Onconase responsive genes in human mesothelioma cells: implications for an RNA damaging therapeutic agent

Our plain-English summary of Onconase responsive genes in human mesothelioma cells: implications for an RNA damaging therapeutic agent, by D.A. Altomare, S.M. Rybak, J. Pei, et al (BMC Cancer, 2010).

The study

• Authors: D.A. Altomare, S.M. Rybak, J. Pei, J.V. Maizel, M. Cheung, J.R. Testa, K. Shogen
• Journal: BMC Cancer
• Published: 2010;10:34
• Cited by: 28 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Onconase represents a new class of RNA-damaging drugs. Mechanistically, Onconase is thought to internalize, where it degrades intracellular RNAs such as tRNA and double-stranded RNA, and thereby suppresses protein synthesis. However, there may be additional or alternative mechanism(s) of action.

Methods: In this study, microarray analysis was used to compare gene expression profiles in untreated human malignant mesothelioma (MM) cell lines and cells exposed to 5 microg/ml Onconase for 24 h. A total of 155 genes were found to be regulated by Onconase that were common to both epithelial and biphasic MM cell lines. Some of these genes are known to significantly affect apoptosis (IL-24, TNFAIP3), transcription (ATF3, DDIT3, MAFF, HDAC9, SNAPC1) or inflammation and the immune response (IL-6, COX-2). RT-PCR analysis of selected up- or down-regulated genes treated with varying doses and times of Onconase generally confirmed the expression array findings in four MM cell lines.

Results: Onconase treatment consistently resulted in up-regulation of IL-24, previously shown to have tumor suppressive activity, as well as ATF3 and IL-6. Induction of ATF3 and the pro-apoptotic factor IL-24 by Onconase was highest in the two most responsive MM cell lines, as defined by DNA fragmentation analysis. In addition to apoptosis, gene ontology analysis indicated that pathways impacted by Onconase include MAPK signaling, cytokine-cytokine-receptor interactions, and Jak-STAT signaling.

Conclusions: These results provide a broad picture of gene activity after treatment with a drug that targets small non-coding RNAs and contribute to our overall understanding of MM cell response to Onconase as a therapeutic strategy. The findings provide insights regarding mechanisms that may contribute to the efficacy of this novel drug in clinical trials of MM patients who have failed first line chemotherapy or radiation treatment.

In plain English

This was a laboratory study of human malignant mesothelioma cell lines grown in dishes. It did not involve patients and did not study asbestos exposure. The authors treated cell lines from pleural tumors with Onconase (ranpirnase), an experimental drug that damages RNA, mainly at 5 micrograms per millilitre for 24 hours. They compared gene activity with untreated cells by microarray in three cell lines and checked selected genes by RT-PCR in four. They found 155 genes that changed in the same direction in all three microarray cell lines: 66% went up and 34% went down. ATF3, IL-24 and IL-6 were confirmed as increased in all four cell lines tested, by widely varying amounts. COX-2 rose in two of four. ATF3 and IL-24 rose most in M35, a cell line that responded strongly to the drug on a DNA fragmentation test, and least in M25, which responded poorly. Genes in MAPK signaling (p = 0.00006) and cytokine-cytokine-receptor interaction (p = 0.006) were affected. The authors concluded that an RNA-damaging drug can affect many of the same genes and pathways as standard chemotherapy.

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 using gene expression microarrays, confirmed by quantitative real-time RT-PCR, plus cell viability and DNA fragmentation assays
• Who was studied: Five human malignant mesothelioma cell lines (M25, M29, M35, M42, M49) from pleural tumors. M25 and M35 were biphasic; M29, M42 and M49 were epithelial. The microarray used M25, M29 and M49; RT-PCR used M25, M29, M35 and M42.
• Exposure: The drug Onconase at 5 μg/ml for 24 h for the microarray. Further RT-PCR tests used doses of 2.5 to 10 μg/ml and times of 24 to 72 h. No asbestos exposure was studied.
• Main results:
  • In all cell lines, loss of viability depended on dose and time, and none of the Onconase-treated cell lines reached an IC50 (half-maximal effect) at 24 h
  • Of the 155 genes changed in all three microarray cell lines, 66% were up-regulated (average 1.2- to 14.6-fold) and 34% down-regulated
  • By RT-PCR across the four cell lines tested, ATF3 rose 3-fold to more than 400-fold, IL-24 2- to nearly 1000-fold, and IL-6 2- to nearly 100-fold
  • COX-2 was confirmed as increased in two of the four cell lines
  • ATF3 and IL-24 induction was highest in M35 (highly responsive by DNA fragmentation) and lowest in M25 (poorly responsive)
  • Onconase-regulated genes were enriched in MAPK signaling (p = 0.00006) and cytokine-cytokine-receptor interaction (p = 0.006); Jak-STAT signaling had p = 0.06
• The authors' conclusion: The authors concluded that an RNA-damaging drug can affect many of the same genes and pathways as standard chemotherapy drugs, and that several new genes are implicated in mesothelioma cells' response to Onconase
• Limitations the authors state:
  • Whether ATF3 and IL-24 actually drive the cells' response to Onconase was not established; the authors say future studies are needed
  • One microarray cell line (M49) grew poorly and was not used for the follow-up RT-PCR analysis

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: Mesothelioma, Biphasic Mesothelioma, Apoptosis, Inflammation, Cytokine, Clinical Trial, Chemotherapy.

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• Modulation of Calretinin Expression in Human Mesothelioma Cells Reveals the Implication of the FAK and Wnt Signaling Pathways in Conferring Chemoresistance towards Cisplatin — J. Wörthmüller, V. Salicio, et al. (2019)
• Combination of onconase and dihydroartemisinin synergistically suppresses growth and angiogenesis of non-small-cell lung carcinoma and malignant mesothelioma — R. Shen, J. Li, et al. (2016)

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