A STAT3-NFkB/DDIT3/CEBPβ axis modulates ALDH1A3 expression in chemoresistant cell subpopulations

Our plain-English summary of A STAT3-NFkB/DDIT3/CEBPβ axis modulates ALDH1A3 expression in chemoresistant cell subpopulations, by C. Canino, Y. Luo, P. Marcato, et al (Oncotarget, 2015).

The study

• Authors: C. Canino, Y. Luo, P. Marcato, G. Blandino, H.I. Pass, M. Cioce
• Journal: Oncotarget
• Published: 2015;6(14):12637-53
• Cited by: 70 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Here we studied the relevance and modulation of aldehyde dehydrogenase (ALDH) expression in malignant pleural mesothelioma (MPM) chemoresistant cell subpopulations (ALDH(bright) cells), which survive pemetrexed + cisplatin treatment in vitro and in vivo. Expression of the ALDH1A3 isoform was invariably enriched in purified ALDH(bright) cells from multiple MPM cell lines and accounted for the enzymatic activity of those cells. RNAi mediated downregulation of ALDH1A3 reduced the survival of the ALDH(bright) cells at steady state and, much more, after pemetrexed + cisplatin treatment. We demonstrated, for the first time, that a pSTAT3(tyr705)-NFkB(p65) complex is required for the repression of DDIT3 mRNA and this ensures high levels of CEBPβ-dependent ALDH1A3 promoter activity. Inhibition of STAT3-NFkB activity allowed high levels of DDIT3 expression with increased formation of a DDIT3-CEBPβ complex. This reduced the occupancy of the ALDH1A3 promoter by CEBPβ, thus largely reducing the ALDH1A3 expression. Consequently, survival of ALDH(bright) cells in pemetrexed + cisplatin-treated cultures was impaired, following increased apoptosis. We show that such a mechanism is relevant in vivo and underlies the action of butein, a dual STAT3-NFkB inhibitor capable of abating the chemoresistance of mesothelioma cells in vivo. The possible broad translational relevance of the described mechanism is discussed.

In plain English

This was a laboratory study of malignant pleural mesothelioma (MPM) using human MPM cell lines and mice carrying tumors grown from one cell line (MSTO-211H). It did not study patients or asbestos exposure. The authors examined a small group of tumor cells with high activity of the enzyme aldehyde dehydrogenase (called ALDHbright cells) that survive the chemotherapy drugs pemetrexed and cisplatin. One form of the enzyme, ALDH1A3, was enriched in these cells in all cell lines analyzed. Lowering ALDH1A3 reduced the number of ALDHbright cells. A compound called butein reduced ALDHbright cells in 10 cell lines. The authors traced this to a chain of proteins. Butein interfered with STAT3 and NFkB, which raised DDIT3. DDIT3 in turn reduced the binding of CEBPβ to the ALDH1A3 gene and lowered ALDH1A3 levels. In mice (6 per group), butein alone reduced tumor weight compared with mice given only the drug-free carrier solution (vehicle), and butein with pemetrexed plus cisplatin reduced it more. Pemetrexed plus cisplatin alone did not reduce tumor weight significantly. The authors concluded that butein may restore the chemotherapy sensitivity of these cells both in culture and in mice.

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 combining experiments on cultured MPM cell lines (in vitro) with mouse xenograft experiments (in vivo)
• Who was studied: Human malignant pleural mesothelioma cell lines (MSTO-211H, H-28, H-2052, H-2591, H-2818, H-2595, H-2373, H-2461, HP-1, H-2596), plus NOD-SCID mice injected with MSTO-211H cells, 6 mice per treatment group
• Exposure: No asbestos exposure was studied. The treatments studied were butein (18 µM in cell culture) and pemetrexed + cisplatin (10 µM + 5 µM), alone or combined. In mice, the doses were printed as butein 5mpk and pemetrexed + cisplatin 45mpk + 7mpk, given as 4 intraperitoneal injections. Control mice received a vehicle of 20% DMSO and 80% corn oil.
• Main results:
  • In cultured MPM cell lines (n=10), butein alone or combined with pemetrexed + cisplatin reduced the number of ALDHbright cells (p less than 0.05)
  • In sorted cells from 6 cell lines, ALDH1A3 (and to a much lesser extent ALDH1A1 and ALDH2) was enriched in ALDHbright cells of all lines analyzed
  • Of the three ALDH forms knocked down, only lowering ALDH1A3 was linked to fewer ALDHbright cells
  • In ALDHbright cells, lowering ALDH1A3 mimicked the effect of butein on cell viability and did not significantly add to it
  • Butein reduced the binding of CEBPβ to the ALDH1A3 promoter in MSTO-211H and HP-1 cells
  • Butein reduced the binding of STAT3, phosphorylated STAT3 and NFkB to the DDIT3 promoter in MSTO-211H cells
  • ALDHbright cells from all 6 cell lines tested had lower DDIT3 mRNA than ALDHlow cells
  • In mice, butein alone and, more strongly, butein with pemetrexed + cisplatin reduced tumor weight at day 24 compared with vehicle-treated mice (p less than 0.05)
  • In mice treated with pemetrexed + cisplatin alone, tumor weight was not significantly reduced compared with vehicle
  • Only 4 of 6 tumors were detectable in mice given butein plus pemetrexed + cisplatin
  • The percentage of ALDHbright cells was significantly reduced in butein-treated mouse tumors
  • Cells from tumors treated with butein plus pemetrexed + cisplatin lost much of their ability to form spheres in 3D culture, compared with tumors treated with pemetrexed + cisplatin alone
• The authors' conclusion: The authors concluded that butein can increase DDIT3 levels in ALDHbright cells, and that this may restore the sensitivity of these cells to chemotherapy-induced stress both in culture and in mice
• Limitations the authors state:
  • The survival of ALDHbright cells may depend on other pathways affected by DDIT3/CEBPβ that the study did not address
  • The study did not address how ALDH1A3 helps these cells tolerate stress
  • Mouse tumor samples were unsorted, which the authors say may explain why DDIT3 rose in pemetrexed + cisplatin-treated tumors without matching changes in ALDHbright cells

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Pemetrexed (Alimta), Cisplatin, Apoptosis, Mesothelioma.

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• Characterization of bortezomib-adapted I-45 mesothelioma cells — L. Zhang, J.E. Littlejohn, et al. (2010)
• Isolation of Chemoresistant Cell Subpopulations — C. Canino, M. Cioce (2016)
• Thymidylate synthase expression determines pemetrexed targets and resistance development in tumour cells — A. Buqué, U. Aresti, et al. (2013)
• A Redox-Silent Analogue of Tocotrienol May Break the Homeostasis of Proteasomes in Human Malignant Mesothelioma Cells by Inhibiting STAT3 and NRF1 — K. Ishii, M. Fusegi, et al. (2022)
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