The RabGEF ALS2 is a hypoxia inducible target associated with the acquisition of aggressive traits in tumor cells

Sci Rep. 2020 Dec 18;10(1):22302. doi: 10.1038/s41598-020-79270-6.

Abstract

Tumor hypoxia and the hypoxia inducible factor-1, HIF-1, play critical roles in cancer progression and metastasis. We previously showed that hypoxia activates the endosomal GTPase Rab5, leading to tumor cell migration and invasion, and that these events do not involve changes in Rab protein expression, suggesting the participation of intermediate activators. Here, we identified ALS2, a guanine nucleotide exchange factor that is upregulated in cancer, as responsible for increased Rab5-GTP loading, cell migration and metastasis in hypoxia. Specifically, hypoxia augmented ALS2 mRNA and protein levels, and these events involved HIF-1α-dependent transcription, as shown by RNAi, pharmacological inhibition, chromatin immunoprecipitation and bioinformatics analyses, which identified a functional HIF-1α-binding site in the proximal promoter region of ALS2. Moreover, ALS2 and Rab5 activity were elevated both in a model of endogenous HIF-1α stabilization (renal cell carcinoma) and by following expression of stable non-hydroxylatable HIF-1α. Strikingly, ALS2 upregulation in hypoxia was required for Rab5 activation, tumor cell migration and invasion, as well as experimental metastasis in C57BL/6 mice. Finally, immunohistochemical analyses in patient biopsies with renal cell carcinoma showed that elevated HIF-1α correlates with increased ALS2 expression. Hence, this study identifies ALS2 as a novel hypoxia-inducible gene associated with tumor progression and metastasis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amyotrophic Lateral Sclerosis / genetics*
  • Amyotrophic Lateral Sclerosis / pathology
  • Animals
  • Carcinoma, Renal Cell / genetics*
  • Carcinoma, Renal Cell / pathology
  • Cell Line, Tumor
  • Cell Movement / genetics
  • Cell Proliferation / genetics
  • Gene Expression Regulation, Neoplastic / genetics
  • Guanine Nucleotide Exchange Factors / genetics*
  • Humans
  • Hypoxia-Inducible Factor 1, alpha Subunit / genetics*
  • Mice
  • Neoplasm Invasiveness / genetics
  • Neoplasm Invasiveness / pathology
  • Transcriptional Activation / genetics
  • Tumor Hypoxia
  • rab5 GTP-Binding Proteins / genetics

Substances

  • Als2 protein, mouse
  • Guanine Nucleotide Exchange Factors
  • Hif1a protein, mouse
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • rab5 GTP-Binding Proteins

Supplementary concepts

  • Amyotrophic Lateral Sclerosis 2, Juvenile