Inhibition of mesothelioma cancer stem-like cells with adenovirus-mediated NK4 gene therapy

Our plain-English summary of Inhibition of mesothelioma cancer stem-like cells with adenovirus-mediated NK4 gene therapy, by X.B. Deng, L. Xiao, Y. Wu, et al (International Journal of Cancer, 2015).

The study

• Authors: X.B. Deng, L. Xiao, Y. Wu, F. Jin, B. Mossman, J.R. Testa, G.H. Xiao
• Journal: International Journal of Cancer
• Published: 2015;137(2):481-90
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Malignant mesothelioma (MM) is a highly invasive and chemoresistant malignancy induced by asbestos fibers. NK4, a hepatocyte growth factor antagonist and angiogenesis inhibitor, consists of the N-terminal hairpin domain and four kringle domains of the α-chain of hepatocyte growth factor. The therapeutic potential of NK4 has been demonstrated in a variety of tumor types. However, the mechanisms by which NK4 inhibits tumor growth have not been well delineated. In this study, it is shown that the NK4 adenovirus (Ad-NK4) potently inhibits cell viability, invasiveness and tumorigenicity of human MM cells. Significantly, this study demonstrates for the first time that Ad-NK4 inhibits cancer stem-like cell (CSC) properties as assessed by spheroid formation assay, side population analysis and flow cytometric sorting of CD24 cells. In addition to inhibiting phosphorylation of Met and AKT, Ad-NK4 markedly suppressed the active form of β-catenin, a key mediator of both Wnt and AKT pathways. It is further demonstrated that expression of NK4 suppresses β-catenin nuclear localization and transcriptional activity. Intriguingly, the expression levels of Oct4 and Myc, two critical stem cell factors and downstream targets of β-catenin, were also diminished by Ad-NK4. Furthermore, the strong antitumor effect of NK4 was found to be linked to its ability to inhibit CSCs as revealed by immunohistochemical examination of tumor specimens from a mouse xenograft model of human MM. These findings suggest that NK4 acts as a CSC inhibitor by impeding Met/AKT/β-catenin signaling and holds promise for achieving durable therapeutic responses in MM by constraining the CSC component of these aggressive tumors.

© 2014 UICC.

In plain English

This laboratory study tested a possible gene therapy for malignant mesothelioma. It did not study asbestos exposure or patients. The authors used two human mesothelioma cell lines, Hmeso (from a biphasic tumor) and Meso 10 (from an epithelioid tumor), and nude mice given Hmeso tumors in the abdomen, in three groups of six. Cells and mice received an adenovirus carrying NK4, a blocker of hepatocyte growth factor (Ad-NK4). The comparisons were a control virus (Ad-LacZ) and mock or salt-solution (PBS) treatment. In cells, Ad-NK4 significantly reduced cell viability and invasion. It reduced markers of cancer stem-like cells. CD24-positive cells fell from 2.8% (Hmeso) and 1.9% (Meso 10) to 1.3–0.6% across the two lines, and sphere formation was severely inhibited. Ad-NK4 lowered activated Met and the active form of beta-catenin. It lowered Oct4 in both lines but Myc only in Hmeso. In mice, Ad-NK4 led to a highly significant decrease in tumor growth compared with either control (p less than 0.01). The authors concluded that NK4 may act as a cancer stem-like cell inhibitor by suppressing Met/AKT/beta-catenin signaling.

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 study: experiments on human mesothelioma cell lines plus an animal (mouse xenograft) experiment
• Who was studied: Two human malignant mesothelioma cell lines: Meso 10 (from a primary epithelioid MM) and Hmeso (from a biphasic MM). Also nude mice injected intraperitoneally with Hmeso cells and randomly divided into three groups of six.
• Exposure: Not an asbestos exposure study. The treatment was an adenovirus carrying the NK4 gene (Ad-NK4), compared with control adenovirus Ad-LacZ and with mock infection or PBS. Cells were infected at a multiplicity of infection of 100. Mice received five injections, twice a week.
• Main results:
  • Ad-NK4 significantly inhibited cell viability in both Hmeso and Meso 10 cells.
  • Ad-NK4 significantly inhibited invasiveness of both cell lines in a Matrigel invasion assay.
  • Untreated Hmeso and Meso 10 cells contained 1.6% and 0.8% side-population cells respectively. Ad-NK4 markedly decreased this percentage in both lines.
  • Uninfected Hmeso and Meso 10 cells contained 2.8% and 1.9% CD24-positive cells respectively.
  • Ad-NK4 significantly reduced CD24-positive cells to 1.3–0.6% in the two cell lines.
  • Spheroid (sphere) formation by Ad-NK4-infected cells was severely inhibited in both cell lines.
  • Phosphorylated (activated) Met was markedly decreased by Ad-NK4 but not by Ad-LacZ.
  • Active beta-catenin was decreased by Ad-NK4 but not by Ad-LacZ, in both cell lines.
  • Ad-NK4 reduced Oct4 in both cell lines, but reduced Myc only in Hmeso cells.
  • Nanog levels were unchanged in both cell lines.
  • Ad-NK4 markedly inhibited beta-catenin-dependent reporter (TOP-Flash) activity.
  • NK4 was more effective than the Met kinase inhibitor PHA-665752 at suppressing mesothelioma spheroid formation.
  • In mice, Ad-NK4 produced a highly significant decrease in tumor growth (average tumor weight per mouse) compared with PBS or Ad-LacZ (p less than 0.01).
  • In mice, Ad-LacZ had a mild effect on tumor growth compared with PBS that was not statistically significant (p greater than 0.05).
  • In tumors from Ad-NK4-treated mice, staining for beta-catenin and Oct4 was abrogated compared with control tumors.
• The authors' conclusion: The authors concluded that their results suggest NK4 acts as a cancer stem-like cell inhibitor by suppressing Met/AKT/beta-catenin signaling, and that this provides a novel mechanism for its antitumor effect.

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, STEM, Angiogenesis.

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• Gene therapy using adenovirus carrying the herpes simplex-thymidine kinase gene to treat in vivo models of human malignant mesothelioma and lung cancer — H.C. Hwang, W.R. Smythe, et al. (1995)
• Adenovirus-mediated wild-type p53 overexpression reverts tumourigenicity of human mesothelioma cells — M. Giuliano, A. Catalano, et al. (2000)
• Chemotherapy delivered after viral immunogene therapy augments antitumor efficacy via multiple immune-mediated mechanisms — Z.G. Fridlender, J. Sun, et al. (2010)
• Tumor suppressor alterations cooperate to drive aggressive mesotheliomas with enriched cancer stem cells via a p53-miR-34a-c-Met axis — C.W. Menges, Y. Kadariya, et al. (2014)

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