Iron-bound lipocalin-2 protects renal cell carcinoma from ferroptosis
While the importance of the iron-load of lipocalin-2 (Lcn-2) in promoting tumor progression is widely appreciated, underlying molecular mechanisms largely remain elusive. Considering its role as an iron-transporter, we aimed at clarifying iron-loaded, holo-Lcn-2 (hLcn-2)-dependent signaling pathways...
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| Main Authors: | , , , , , , , , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
19 May 2021
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| In: |
Metabolites
Year: 2021, Volume: 11, Issue: 5, Pages: 1-21 |
| ISSN: | 2218-1989 |
| DOI: | 10.3390/metabo11050329 |
| Online Access: | Verlag, lizenzpflichtig, Volltext: https://doi.org/10.3390/metabo11050329 Verlag, lizenzpflichtig, Volltext: https://www.mdpi.com/2218-1989/11/5/329 
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| Author Notes: | Julia K. Meier, Matthias Schnetz, Susanne Beck, Tobias Schmid, Monica Dominguez, Sanela Kalinovic, Andreas Daiber, Bernhard Brüne and Michaela Jung |
| Summary: | While the importance of the iron-load of lipocalin-2 (Lcn-2) in promoting tumor progression is widely appreciated, underlying molecular mechanisms largely remain elusive. Considering its role as an iron-transporter, we aimed at clarifying iron-loaded, holo-Lcn-2 (hLcn-2)-dependent signaling pathways in affecting renal cancer cell viability. Applying RNA sequencing analysis in renal CAKI1 tumor cells to explore highly upregulated molecular signatures in response to hLcn-2, we identified a cluster of genes (SLC7A11, GCLM, GLS), which are implicated in regulating ferroptosis. Indeed, hLcn-2-stimulated cells are protected from erastin-induced ferroptosis. We also noticed a rapid increase in reactive oxygen species (ROS) with subsequent activation of the antioxidant Nrf2 pathway. However, knocking down Nrf2 by siRNA was not sufficient to induce erastin-dependent ferroptotic cell death in hLcn-2-stimulated tumor cells. In contrast, preventing oxidative stress through N-acetyl-l-cysteine (NAC) supplementation was still able to induce erastin-dependent ferroptotic cell death in hLcn-2-stimulated tumor cells. Besides an oxidative stress response, we noticed activation of the integrated stress response (ISR), shown by enhanced phosphorylation of eIF-2α and induction of ATF4 after hLcn-2 addition. ATF4 knockdown as well as inhibition of the ISR sensitized hLcn-2-treated renal tumor cells to ferroptosis, thus linking the ISR to pro-tumor characteristics of hLcn-2. Our study provides mechanistic details to better understand tumor pro-survival pathways initiated by iron-loaded Lcn-2. |
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| Item Description: | Gesehen am 28.06.2021 |
| Physical Description: | Online Resource |
| ISSN: | 2218-1989 |
| DOI: | 10.3390/metabo11050329 |