Abstract | 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.
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Authors | Shweta Joshi, Alok R Singh, Donald L Durden |
Journal | Cancer chemotherapy and pharmacology
(Cancer Chemother Pharmacol)
Vol. 75
Issue 3
Pg. 595-608
(Mar 2015)
ISSN: 1432-0843 [Electronic] Germany |
PMID | 25578041
(Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
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Chemical References |
- Angiogenesis Inhibitors
- Antineoplastic Agents
- Chromones
- Hypoxia-Inducible Factor 1, alpha Subunit
- Oligopeptides
- Phosphoinositide-3 Kinase Inhibitors
- Prodrugs
- SF 1126
- Von Hippel-Lindau Tumor Suppressor Protein
- VHL protein, human
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Topics |
- Angiogenesis Inhibitors
(pharmacology)
- Animals
- Antineoplastic Agents
(pharmacology)
- Carcinoma, Renal Cell
(drug therapy, pathology)
- Cell Line, Tumor
- Chromones
(pharmacology)
- Female
- Humans
- Hypoxia-Inducible Factor 1, alpha Subunit
(drug effects, metabolism)
- Injections, Subcutaneous
- Kidney Neoplasms
(drug therapy, pathology)
- Mice
- Mice, Nude
- Oligopeptides
(pharmacology)
- Phosphoinositide-3 Kinase Inhibitors
- Prodrugs
- Von Hippel-Lindau Tumor Suppressor Protein
(genetics)
- Xenograft Model Antitumor Assays
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