8-Chloroadenosine Sensitivity in Renal Cell Carcinoma Is Associated with AMPK Activation and mTOR Pathway Inhibition.

Abstract

The adenosine analog 8-chloroadenosine has been shown to deplete ATP and inhibit tumor growth in hematological malignancies as well as in lung and breast cancer cell lines. We investigated effects of 8-chloroadenosine on clear cell (cc) renal cell carcinoma (RCC) cell lines. 8-chloroadenosine was effective against ccRCC cell viability in vitro, with IC50 ranging from 2 μM in the most sensitive CAKI-1 to 36 μM in the most resistant RXF-393. Proteomic analysis by reverse-phase protein array revealed that 8-chloroadenosine treatment leads to inhibition of the mTOR pathway. In time-course experiments, 8-chloroadenosine treatment rapidly activated AMPK, measured by AMPK and ACC phosphorylation, and subsequently caused dephosphorylation of p70S6K and ribosomal protein RPS6 in the sensitive cell lines. However, in the resistant cell lines, AMPK activity and the mTOR pathway were unaffected by the treatment. We also noted that the resistant cell lines had elevated basal levels of phospho RPS6 and AKT. Inhibition of PI3K pathway enhanced the efficacy of 8-chloroadenosine across all cell lines. Our observations indicate that 8-chloroadenosine activity is associated with inhibition of the mTOR pathway, and that phospho RPS6 and PI3K pathway activation status may determine resistance. Among solid tumors, RCC is one of the few susceptible to mTOR inhibition. We thus infer that 8-chloroadenosine may be effective in RCC by activating AMPK and inhibiting the mTOR pathway.

• Authors: Alper Y Kearney, You-Hong Fan, Uma Giri, Babita Saigal, Varsha Gandhi, John V Heymach, Amado J Zurita
• Journal: PloS one (PLoS One) Vol. 10 Issue 8 Pg. e0135962 ( 2015) ISSN: 1932-6203 [Electronic] United States
• PMID: 26313261 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Phosphoinositide-3 Kinase Inhibitors
• Protein Kinase Inhibitors
• 2-Chloroadenosine
• MTOR protein, human
• Proto-Oncogene Proteins c-akt
• TOR Serine-Threonine Kinases
• AMP-Activated Protein Kinases
• 8-chloroadenosine

Topics

• 2-Chloroadenosine (analogs & derivatives, pharmacology)
• AMP-Activated Protein Kinases (metabolism)
• Blotting, Western
• Carcinoma, Renal Cell (drug therapy, metabolism, pathology)
• Cell Cycle (drug effects)
• Cell Proliferation (drug effects)
• Drug Resistance, Neoplasm (drug effects)
• Humans
• Kidney Neoplasms (drug therapy, metabolism, pathology)
• Phosphatidylinositol 3-Kinases (metabolism)
• Phosphoinositide-3 Kinase Inhibitors
• Phosphorylation (drug effects)
• Protein Array Analysis
• Protein Kinase Inhibitors (pharmacology)
• Proteomics (methods)
• Proto-Oncogene Proteins c-akt (antagonists & inhibitors, metabolism)
• Signal Transduction (drug effects)
• TOR Serine-Threonine Kinases (antagonists & inhibitors, metabolism)
• Tumor Cells, Cultured