Roles of arrest-defective protein 1²²⁵ and hypoxia-inducible factor 1α in tumor growth and metastasis

Background Vascular endothelial growth factor A (VEGFA), a critical mediator of tumor angiogenesis, is a well-characterized target of hypoxia-inducible factor 1 (HIF-1). Murine arrest-defective protein 1A (mARD1A²²⁵) acetylates HIF-1α, triggering its degradation, and thus may play a role in decreased expression of VEGFA.Methods We generated Apc^Min/+/mARD1A²²⁵ transgenic mice and quantified growth of intestinal polyps. Human gastric MKN74 and murine melanoma B16F10 cells overexpressing mARD1A²²⁵ were injected into mice, and tumor growth and metastasis were measured. VEGFA expression and microvessel density in tumors were assessed using immunohistochemistry. To evaluate the role of mARD1A ²²⁵ acetylation of Lys532 in HIF-1α, we injected B16F10-mARD1A²²⁵ cell lines stably expressing mutant HIF-1α/K532R into mice and measured metastasis. All statistical tests were two-sided, and P values less than. 05 were considered statistically significant.Results Apc^Min/+/mARD1A²²⁵ transgenic mice (n = 25) had statistically significantly fewer intestinal polyps than Apc ^Min/+ mice (n = 21) (number of intestinal polyps per mouse: Apc ^Min/+ mice vs Apc^Min/+/mARD1A²²⁵ transgenic mice, mean = 83.4 vs 38.0 polyps, difference = 45.4 polyps, 95% confidence interval [CI] = 41.8 to 48.6; P <. 001). The growth and metastases of transplanted tumors were also statistically significantly reduced in mice injected with mARD1A²²⁵-overexpressing cells than in mice injected with control cells (P <. 01). Moreover, overexpression of mARD1A ²²⁵ decreased VEGFA expression and microvessel density in tumor xenografts (P <. 04) and Apc^Min/+ intestinal polyps (P =. 001). Mutation of lysine 532 of HIF-1α in B16F10-mARD1A²²⁵ cells prevented HIF-1α degradation and inhibited the antimetastatic effect of mARD1A²²⁵ (P <. 001).Conclusion mARD1A²²⁵ may be a novel upstream target that blocks VEGFA expression and tumor-related angiogenesis.