Inhibition of Akt pathway phosphorylation as a mechanism in the pathogenesis of functional intestinal obstruction in carcinomatosis peritonei

The purpose of this study was to confirm our hypothesis that the development of functional intestinal obstruction in carcinomatosis peritonei (CP) is related to cytokine-mediated inhibition of the Akt pathway and to investigate the phenomenon of relative adrenal insufficiency in CP.

Human adrenocortical cells (NCI-H295R) were treated with serum derived from eight cancer patients who had intestinal obstruction and functional adrenal insufficiency. Serum from three normal healthy subjects and three who had CP but without intestinal obstruction or adrenal insufficiency were used as controls. The differential effects of serum on the treated cells were studied using Western blot analysis. Cortisol production of these treated cells was assayed with cortisol ELISA kits.

Phosphorylation of Akt at Ser473 and Ser308 in cells was significantly reduced when treated with serum from patients with intestinal obstruction but not controls. Phosphorylation of PDK1 at Ser241, mTOR downstream targets like p70S6 at Thr421/Ser424 and Thr389, and lastly 4EBP-1 at Ser70 a downstream target of p70S6 was reduced by approximately 50%, 40%, and 70%, respectively. There was enhanced phosphorylation of elF4E an initiating factor in protein translation in cells treated with patient serum compared to controls. Cortisol synthesis was stimulated upon treatment with patient serum but not with control serum.

Inhibition of Akt phosphorylation is a mechanism that could play a major role in the development of intestinal obstruction in carcinomatosis peritonei. The identification of the mediating cytokines will lead to the development of cogent targeted therapeutic strategies.