Pan-PI-3 kinase inhibitor SF1126 shows antitumor and antiangiogenic activity in renal cell carcinoma

Shweta Joshi, Alok R. Singh, Donald L. Durden

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


Purpose: SF1126 is a vascular-targeted pan-PI-3K inhibitor prodrug with antitumor and antiangiogenic activity and has completed phase I clinical trial in solid tumors and B-cell malignancies. In this study, we investigated the effect of SF1126 on hypoxic HIF-1α/HIF-2α stability as well as on antitumor and/or antiangiogenic activity in renal cell carcinoma (RCC) models in vitro and in vivo. Methods: The effect of SF1126 on hypoxic HIF-1α/HIF-2α protein stability, antitumor and antiangiogenic activity was studied on VHL-null (786-0) and VHL-WT (Caki) RCC cells. Results: Our data demonstrate that SF1126 treatment abrogates the stabilization of HIF-2α in 786-0 (VHL-mutated) RCC cell line under normoxic and hypoxic conditions. Similarly, hypoxic stabilization of HIF-1α and its activity were also suppressed following SF1126 treatment in Caki cell line (VHL-WT). Herein, we provide mechanistic evidence that HIF-2α can be degraded in cytoplasm under hypoxic conditions via the 26S proteasome and that MDM2 is the E3 ligase which induces the hypoxic degradation of HIF-2α in PI-3K-dependent manner in VHL-deficient RCC cells. Moreover, SF1126 administered to RCC-xenografted mice at 25 mg/kg/dose subcutaneously three times per week for 3 weeks results in marked inhibition of tumor growth (>90 % inhibition) (P < 0.05). Consistent with SF1126 treatment's effects on HIF-1α/HIF-2α, microvessel density analysis of Caki and 786-0 tumor tissues demonstrated that SF1126 has potent antiangiogenic activity in vivo. Finally, SF1126 caused a profound inhibition of integrin-mediated migration and blocked the integrin-induced conversion of GDP-Rac1 to its GTP-bound active state. Conclusions: These results validate the in vivo efficacy of SF1126 as a clinically viable antiangiogenic, pan-PI-3K inhibitor prodrug for phase II clinical trials in the treatment of RCC.

Original languageEnglish (US)
Pages (from-to)595-608
Number of pages14
JournalCancer Chemotherapy and Pharmacology
Issue number3
StatePublished - Mar 2015
Externally publishedYes


  • HIFα
  • Pan-PI-3 kinase
  • Renal cell carcinoma
  • SF1126

ASJC Scopus subject areas

  • Oncology
  • Toxicology
  • Pharmacology
  • Cancer Research
  • Pharmacology (medical)


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