Loss of the von Hippel Lindau tumor suppressor disrupts iron homeostasis in renal carcinoma cells

Alessandra Alberghini, Stefania Recalcati, Lorenza Tacchini, Paolo Santambrogio, Alessandro Campanella, Gaetano Cairo

Research output: Contribution to journalArticlepeer-review

Abstract

Given the modulation of iron metabolism by hypoxia and the high iron requirement of neoplastic cells, we investigated iron metabolism in a human renal cancer cell line with a mutated von Hippel Lindau (VHL) tumor suppressor gene (RCC10) and in a transfectant clone with wild-type VHL (RCC63). The loss of VHL strongly up-regulated transferrin receptor expression in RCC10 cells as a result of hypoxia inducible factor-1 (HIF-1)-mediated transcriptional activation, leading to an increased uptake of transferrin-bound 55Fe. Increased iron availability did not compromise the resistance of VHL-defective cells to oxidative stress or promote faster cell multiplication. Surprisingly, the content of ferritin H and L subunits and ferritin mRNA levels were considerably lower in the RCC10 than in the RCC63 cells. Despite the similarities between HIF-1 and iron regulatory protein 2 (IRP2), we found no evidence of specific regulation of IRP2 by VHL. However, both IRP2 and IRP1 were slightly activated in RCC10 cells, thus indicating that this cell line has a somewhat reduced labile iron pool (LIP). The finding that RCC10 cells had a lower ferritin content but more ferritin-associated 55Fe than RCC63 explains why VHL-lacking cells may have a smaller LIP despite increased iron uptake. We also found a correlation between cytoprotection from iron-mediated damage and efficient incorporation into ferritin of both transferrin and non-transferrin-bound 55Fe. This study shows that, like oncogene activation, the loss of an oncosuppressor rearranges the expression pattern of the genes of iron metabolism to increase iron availability. However, in the case of VHL loss, mechanisms affecting iron handling by ferritin somehow counteract the effects that the reduced content of this protective protein may have on proliferation and oxidant sensitivity.

Original languageEnglish
Pages (from-to)30120-30128
Number of pages9
JournalJournal of Biological Chemistry
Volume280
Issue number34
DOIs
Publication statusPublished - Aug 26 2005

ASJC Scopus subject areas

  • Biochemistry

Fingerprint Dive into the research topics of 'Loss of the von Hippel Lindau tumor suppressor disrupts iron homeostasis in renal carcinoma cells'. Together they form a unique fingerprint.

Cite this