RGS19 converts iron deprivation stress into a growth-inhibitory signal

Area of Science:

• Cellular signaling pathways
• Cancer biology
• Molecular mechanisms of iron metabolism

Background:

• Iron chelation therapy shows promise for cancer treatment by upregulating N-myc downstream-regulated gene 1 protein (NDRG1).
• The precise signaling pathways linking cellular stress to biological responses like NDRG1 overexpression are not fully understood.

Purpose of the Study:

• To investigate the role of Regulator of G-protein signaling 19 (RGS19) in iron chelator-induced NDRG1 overexpression.
• To elucidate the mechanism by which RGS19 influences cancer cell growth and metastasis suppression.

Main Methods:

• Utilized HeLa cells with RGS19 knockdown and overexpression.
• Investigated the impact of G-protein alpha subunit i3 (Gαi3) and its downstream targets.
• Analyzed RGS19 stability, proteolysis, and interaction with iron using biochemical assays and mutant analysis.

Main Results:

• RGS19 knockdown reduced expression of genes involved in desferrioxamine (DFO)-induced growth inhibition.
• RGS19 overexpression enhanced these genes and reduced cell viability.
• Gαi3 overexpression repressed NDRG1 induction, and its inhibition abrogated DFO-induced NDRG1 overexpression.
• DFO protected RGS19 from proteolysis, and an iron-deficient RGS19 mutant remained stable.

Conclusions:

• RGS19 acts as an iron sensor, becoming stabilized under iron-depleted conditions.
• Stabilized RGS19 initiates a growth-inhibitory signal through NDRG1 induction.
• This pathway represents a novel mechanism linking iron availability to cancer cell growth and metastasis.