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


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Poon
Donald
D
Department of Medical Oncology, Division of Cellular and Molecular Research, National Cancer Centre, Singapore.
Le
Hoang-Vinh
HV
Van Chanh
Ngo
N
Tham
Chee-Kian
CK
Poh
Benjamin
B
Koo
Wen-Hsin
WH
Hung
Huynh
H
D000309:Adrenal Insufficiency / Q000150:complications; D015153:Blotting, Western; D002277:Carcinoma / Q000150:complications / Q000378:metabolism* / Q000503:physiopathology; D045744:Cell Line, Tumor; D006801:Humans; D007415:Intestinal Obstruction / Q000209:etiology / Q000378:metabolism* / Q000503:physiopathology; D010534:Peritoneal Neoplasms / Q000150:complications / Q000378:metabolism* / Q000503:physiopathology; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*
D051057:Proto-Oncogene Proteins c-akt