Isoflurane, a Commonly Used Volatile Anesthetic, Enhances Renal Cancer Growth and Malignant Potential via the Hypoxia-inducible Factor Cellular Signaling Pathway In Vitro

Background: Growing evidence indicates that perioperative factors, including choice of anesthetic, affect cancer recurrence after surgery although little is known about the effect of anesthetics on cancer cells themselves. Certain anesthetics are known to affect hypoxia cell signaling mechanisms in healthy cells by up-regulating hypoxia-inducible factors (HIFs). HIFs are also heavily implicated in tumorigenesis and high levels correlate with poor prognosis. Methods: Renal cell carcinoma (RCC4) cells were exposed to isoflurane for 2 h at various concentrations (0.5-2%). HIF-1, HIF-2, phospho-Akt, and vascular endothelial growth factor A levels were measured by immunoblotting at various time points (0-24 h). Cell migration was measured across various components of extracellular matrix, and immunocytochemistry was used to analyze proliferation rate and cytoskeletal changes. Results: Isoflurane up-regulated levels of HIF-1 and HIF-2 and intensified expression of vascular endothelial growth factor A. Exposed cultures contained significantly more cells (1.81 +/- 0.25 vs. 1.00 of control; P = 0.03) and actively proliferating cells (89.4 +/- 2.80 vs. 64.74 +/- 7.09% of control; P = 0.016) than controls. These effects were abrogated when cells were pretreated with the Akt inhibitor, LY294002. Exposed cells also exhibited greater migration on tissue culture-coated (F = 16.89; P = 0.0008), collagen-coated (F = 20.99; P = 0.0003), and fibronectin-coated wells (F = 8.21; P = 0.011) as along with dramatic cytoskeletal rearrangement, with changes to both filamentous actin and -tubulin. Conclusions: These results provide evidence that a frequently used anesthetic can exert a protumorigenic effect on a human cancer cell line. This may represent an important contributory factor to high recurrence rates observed after surgery.