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

Abstract

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.

AICA‐ribosiduria due to ATIC deficiency: Delineation of the phenotype with three novel cases, and long‐term update on the first case

“…AICAR/ZMP is also capable of inducing cellular apoptosis in human osteosarcoma cells, 19 or in gallbladder cancer cells through a cytotoxic mechanism involving endoplasmic reticulum‐stress activation 20 . AICA‐riboside has also demonstrated pro‐apoptotic abilities in a cellular model of von Hippel‐Lindau renal carcinoma and been able to reduce the size of renal tumors in a mouse model 21 . Its AMPK‐independent anti‐tumoral properties could result from the activation of the tumor suppressor genes LATS1 and LATS2 22 .…”

“…20 AICA-riboside has also demonstrated pro-apoptotic abilities in a cellular model of von Hippel-Lindau renal carcinoma and been able to reduce the size of renal tumors in a mouse model. 21 Its AMPK-independent anti-tumoral properties could result from the activation of the tumor suppressor genes LATS1 and LATS2. 22 AICA-riboside has been subjected to phase I/II clinical trials for treating chronic lymphocytic leukemia 23 and seems to be relatively well tolerated in doses probably vastly inferior to those in AICA-ribosiduria.…”

Role of Hypoxic Stress in Regulating Tumor Immunogenicity, Resistance and Plasticity

“…Translation of HIF1 mRNA is known to be controlled by the PI3K/AKT/mTOR pathway. Inhibition of this pathway could decrease HIF expression and the resultant tumorigenesis [ 168 , 169 , 170 ]. As an alternative, targeting pathways downstream of HIF signaling includes the use of anti-VEGF therapy (monoclonal antibodies targeting VEGF (bevacizumab) or small molecule inhibitors targeting the VEGF receptor), which has been used for anti-angiogenic/vascular normalization effects in certain medical indications including ovarian, renal, lung or colorectal cancers, in combination with chemotherapy [ 171 ].…”

Prognostic Implication of pAMPK Immunohistochemical Staining by Subcellular Location and Its Association with SMAD Protein Expression in Clear Cell Renal Cell Carcinoma

“…In other words, pAMPK shifts metabolism away from the Warburg effect-like status, an environment that is supportive of ccRCC progression [1,6,7,24]. Our clinical results as well as previous preclinical data propose that AMPK activation may be useful as a ccRCC treatment strategy [25,26]. pAMPK expression may affect the treatment response to targeted agents in ccRCC.…”

“…pAMPK inhibits growth, invasion, EMT, and metastasis by modulating various signaling axes, including downregulation of mTORC1, HIF, and NF-κB and upregulation of Forkhead box class O (FoxO)3a and p53 [7,12,23,24,25]. In addition, pAMPK is responsible for restricting ATP-consumption by directly suppressing fatty acid synthesis enzymes, such as acetyl-CoA carboxylase and fatty acid synthase.…”