[720] Expression Analysis of AKT/mTOR Signaling Pathway in Primary Tumors and Cell Lines Derived from Gallbladder Cancer

Juan C Roa, Pamela Leal, Patricia Garcia, Oscar Tapia, Helga Weber. Pontificia Universidad Catolica, Santiago, Chile; Universidad de La Frontera, Temuco, Chile

Background: Gallbladder carcinoma (GBC) is a highly fatal disease with poor prognosis. The mammalian target of rapamycin (mTOR) is a serine/threonine kinase that plays a central role in cell growth and homeostasis. Its regulation is frequently altered in various tumors and is an attractive target for cancer therapy; however, its status in GBC remains unclear.
Objectives: To analyze the expression of mTOR signaling pathway in primary tumors and cell lines derived from gallbladder cancer and to evaluate the in vitro effect of mTOR inhibitors on cell viability and migration.
Design: The expression of five components of AKT/mTOR signaling pathway (phospho- mTOR and total protein of mTOR, AKT, 4EBP1, P70S6K and eIF4e) was examined by immunohistochemistry in tissue microarrays (TMAs) containing 128 advanced GBC and 99 cases of chronic cholecystitis (CC). Association between phospho-mTOR expression and clinical variables was evaluated. We also examined the activation of the AKT/mTOR pathway based on phospho-AKT, phospho-p70S6K, phospho-4EBP1 and phospho-eIF4E expression in eight GBC cell lines by Western blot. Finally, the effect of four mTOR inhibitors (LY294002, Rapamycin, Everolimus and AZD8055) on cell viability and in vitro migration was assessed by MTS and Transwell chamber assays. Statistical analysis was performed using a significance level P < 0.05.
Results: We observed a significant IHC overexpression of AKT-mTor pathway component in primary tumor samples, compared to CC.

Immunohistochemical expression of AKT-mTOR pathway components in GBC and Chronic Cholecystitis (CC).
 CC %GBC %
mTOR44.463.7
AKT48.682.4
4EBP113.153.9
eIF4E4.989.3
P70S6K22.968.1
p-mTOR2464.1


Survival analysis indicated that GBC patients whose tumors overexpressed phospho-mTOR had a poorer prognosis (P = 0.02). TGBC2-TKB cell line showed a constitutive activation of the AKT/mTOR pathway (Western Blot Assay) and the treatment with different mTOR inhibitors significantly reduced its viability and migration capacity (p <0.05).
Conclusions: The AKT/mTOR signaling pathway is abnormally expressed in GBC which suggest that mTOR could be a potential therapeutic target for the treatment of advanced GBC. In addition, phospho-mTOR IHC expression characterizes a subset of GBC cancers that might optimally benefit with anti-mTOR therapies.
FONDECYT Project 1090171 and DIUFRO project DI11-0039.
Category: Gastrointestinal

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 108, Wednesday Morning

 

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