Preclinical evidence of the enhanced effectiveness of combined rapamycin and AICAR in reducing kidney cancer

• Published in: Molecular oncology Vol. 12; no. 11; pp. 1917 - 1934
• Main Authors: Liang, Sitai, Medina, Edward A., Li, Boajie, Habib, Samy L.
• Format: Journal Article
• Language: English
• Published: United States John Wiley & Sons, Inc 01.11.2018; John Wiley and Sons Inc; Wiley
• Subjects: 5‐aminoimidazole‐4‐carboxamide‐riboside (AICAR); AKT protein; Aminoimidazole Carboxamide - analogs & derivatives; Aminoimidazole Carboxamide - pharmacology; Angiogenesis; Animals; Antigens; Antineoplastic Combined Chemotherapy Protocols - pharmacology; Apoptosis; Binding sites; Cancer; Carcinoma, Renal Cell - drug therapy; Carcinoma, Renal Cell - metabolism; Carcinoma, Renal Cell - pathology; Cell Line, Tumor; Cell migration; Cell proliferation; Clinical trials; Cytomegalovirus; Deoxyribonucleic acid; Development and progression; DNA; DNA repair; Drug therapy, Combination; Flow cytometry; Genes; Humans; Hypoxia; hypoxia‐inducible factor (HIF‐α); Kidney cancer; Kidney Neoplasms - drug therapy; Kidney Neoplasms - metabolism; Kidney Neoplasms - pathology; Kidneys; Kinases; Male; Medical prognosis; Mice; Mice, Nude; Oncology, Experimental; Patients; Phosphorylation; Plasmids; Protein expression; Proteins; Rapamycin; Renal cell carcinoma; Ribonucleotides - pharmacology; Sirolimus - pharmacology; TOR protein; Tumorigenesis; Vascular endothelial growth factor; Von Hippel‐Lindau; Xenograft Model Antitumor Assays; United States > US; kidney cancer; 5-aminoimidazole-4-carboxamide-riboside (AICAR); Von Hippel-Lindau; hypoxia-inducible factor (HIF-α); rapamycin
• ISSN: 1574-7891; 1878-0261
• DOI: 10.1002/1878-0261.12370

Loss of Von Hippel‐Lindau in renal carcinoma cells results in upregulation of the activity of hypoxia‐inducible factor (HIF‐α), a major transcription factor involved in kidney cancer. Rapamycin as mammalian target of rapamycin inhibitor and 5‐aminoimidazole‐4‐carboxamide‐riboside (AICAR) as AMPK activator are used separately to treat cancer patients. In the current study, the possible additive effect of drug combinations in reducing kidney tumorigenesis was investigated. Treatment with drug combinations significantly decreased cell proliferation, increased cell apoptosis, and abolished Akt phosphorylation and HIF‐2α expression in renal cell carcinoma cells, including primary cells isolated from kidney cancer patients. Significant decreases in cell migration and invasion were detected using drug combinations. Drug combinations effectively abolished binding of HIF‐2α to the Akt promoter and effected formation of the DNA‐protein complex in nuclear extracts from 786‐O cells, as demonstrated using electromobility shift assay and examination of Akt promoter activity. Importantly, we tested the effect of each drug and the combined drugs on kidney tumor size in the nude mouse model. Our data show that treatment with rapamycin, AICAR, and rapamycin+AICAR decreased tumor size by 38%, 36%, and 80%, respectively, suggesting that drug combinations have an additive effect in reducing tumor size compared with use of each drug alone. Drug combinations effectively decreased cell proliferation, increased apoptotic cells, and significantly decreased p‐Akt, HIF‐2α, and vascular endothelial growth factor expression in tumor kidney tissues from mice. These results show for the first time that drug combinations are more effective than single drugs in reducing kidney tumor progression. This study provides important evidence that may lead to the initiation of pre‐clinical trials in patients with kidney cancer. Our data provide pre‐clinical evidence for the safety of combining rapamycin and AICAR to repress RCC tumor progression, and demonstrate for the first time in a preclinical mouse model of RCC that this drug combination additively reduces kidney tumor progression.