Exression and PI3K/AKT Pathway in Gastric Cancer and its Blockade Suppresses Tumor Growth and Metastasis

Abstract

Phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway plays a crucial role in the formation and progression of many malignancies, and has been shown to be an important therapeutic target for cancer. In the present study, human gastric adenocarcinoma tissues of different grades (N=45) were collected. The protein expression of PI3Kp85α and phosphorylated AKT (p-AKT) was evaluated immunohistochemically in the biopsy samples. PI3K/AKT pathway was blocked by constructed recombinant small hairpin RNA adenovirus vector rAd5-PI3Kp85α (rAd5-P) used to transfect into human gastric cancer SGC-7901cell line. The transfection efficiency of rAd5-P in SGC-7901 cells was observed under fluorescent microscope. The expression of PI3Kp85α, p-AKT, Ki-67 and matrix metallopeptidase-2 (MMP-2) was detected by Real-time PCR and Western blot assays. Cell proliferative activities and metastatic capabilities were determined by MTT and Transwell assays. As a consequence, the protein expression of PI3Kp85α and p-AKT was respectively observed in 80.0% and 82.2% gastric adenocarcinoma tissues, elevating with the ascending order of tumor malignancy. Targeted blockade of PI3K pathway decreased the expression of PI3Kp85α, p-AKT, Ki-67 and MMP-2, and inhibited the proliferative activities and metastatic capabilities of gastric cancer cells. In conclusion, PI3Kp85a and p-AKT were strongly expressed in gastric adenocarcinoma tissues, and targeted blockade of PI3K pathway may inhibit gastric cancer growth and metastasis through down-regulation of Ki-67 and MMP-2 expression. PI3K/AKT pathway may represent an important therapeutic target for gastric cancer.

Keywords

phosphoinositide 3-kinase protein kinase B RNA interference growth metastasis

References

Jemal

Bray

Center

Ferlay

Ward

Forman

. Global cancer statistics. CA Cancer J Clin 2011; 61:69–90.

Tajima

Yamazaki

Makino

. Gastric and intestinal phenotypic marker expression in early differentiated-type tumors of the stomach: Clinicopathologic significance and genetic background. Clin Cancer Res 2006; 12:6469–79.

Michl

Downward

. Mechanisms of disease: PI3K/AKT signaling in gastrointestinal cancers. Z Gastroenterol 2005; 43:1133–9.

García-Rostán

Costa

Pereira-Castro

. Mutation of the PIK3CA gene in anaplastic thyroid cancer. Cancer Res 2005; 65:10199–207.

Liu

Zhou

Chen

Lin

. Up-regulation of PIK3CA promotes metastasis in gastric carcinoma. World J Gastroenterol 2010; 16:4986–91.

Yoo

Kang

Lee

Kim

Park

Kim

. Sonic hedgehog pathway promotes metastasis and lymphangiogenesis via activation of Akt, EMT, and MMP-9 pathway in gastric cancer. Cancer Res 2011; 71:7061–70.

Liu

Zhang

Hou

Liu

. Phosphoinositide 3-kinase/Akt and nuclear factor kB pathways are involved in tumor necrosis factor-related apoptosis-inducing ligand resistance in human gastric cancer cells. Mol Med Report 2010; 3(3):491–6.

Osaki

Kase

Adachi

Takeda

Hashimoto

Ito

. Inhibition of the PI3K-Akt signaling pathway enhances the sensitivity of Fas-mediated apoptosis in human gastric carcinoma cell line, MKN-45. J Cancer Res Clin Oncol 2004; 130:8–14.

. Phosphoinositide 3-kinase/Akt pathway plays an important role in chemoresistance of gastric cancer cells against etoposide and doxorubicin induced cell death. Int J Cancer 2008; 122:433–43.

10.

Yang

Luo

. Impact of PI3K/Akt/mdm2 signaling pathway on the sensitivity of gastric cancer cell line SGC7901 to doxorubicin. Zhonghua Zhong Liu Za Zhi 2008; 30:494–7.

11.

Hanahan

Weinberg

. The hallmarks of cancer: The next generation. Cell 2011; 144:646–74.

12.

Walker

Perisic

Ried

Stephens

Williams

. Structural insights into phosphoinositide 3-kinase catalysis and signalling. Nature 1999; 402:313–20.

13.

Cantley

. The phosphoinositide 3-kinase pathway. Science 2002; 296:1655–7.

14.

Burgering

Coffer

. Protein kinase B (c-Akt) in phosphatidylinositol-3-OH kinase signal transduction. Nature 1995; 376:599–602.

15.

Stephens

Anderson

Stokoe

. Protein kinase B kinases that mediate phosphatidylinositol 3,4,5-trisphosphate-depent activation of protein kinase B. Science 1998; 279:710–4.

16.

Blume-Jensen

Hunter

. Oncogenic kinase signalling. Nature 2001; 411:355–65.

17.

Kobayashi

Semba

Matsuda

Kuroda

Yokozaki

. Significance of Akt phosphorylation on tumor growth and vascular endothelial growth factor expression in human gastric carcinoma. Pathobiology 2006; 73:8–17.

18.

Chen

Law

Loh

. Inhibition of PI3K/Akt signaling: An emerging paradigm for targeted cancer therapy. Curr Med Chem Anticancer Agents 2005; 5:575–89.

19.

Xing

Zhu

Liu

. LY294002 induces p53-dependent apoptosis of SGC7901 gastric cancer cells. Acta Pharmacol Sin 2008; 29:489–98.

20.

Xing

Zhu

Liu

. Class I phosphatidylinositol 3-kinase inhibitor LY294002 activates autophagy and induces apoptosis through p53 pathway in gastric cancer cell line SGC7901. Acta Biochim Biophys Sin 2008; 40:194–201.

21.

Yuan

Xia

Zhao

. Inhibition of PKB/Akt activity involved in apigenin induced apoptosis in human gastric carcinoma cells. Chinese Science Bulletin 2007; 52:2226–32.

22.

Ohta

Ohmichi

Hayasaka

. Inhibition of phosphatidylinositol 3-kinase increases efficacy of cisplatin in in vivo ovarian cancer models. Endocrinology 2006; 147:1761–9.

23.

Gupta

Cerniglia

Mick

. Radiation sensitization of human cancer cells in vivo by inhibiting the activity of PI3K using LY294002. Int J Radiat Oncol Biol Phys 2003; 56:846–53.

24.

Thomas

Owen

. Inhibition of PI-3 kinase for treating respiratory disease: Good idea or bad idea? Curr Opin Pharmacol 2008; 8:267–74.

25.

Zamore

. RNA interference: Listening to the sound of silence. Nat Struct Biol 2001; 8746–51.

26.

Miao

Zhang

. Downregulation of survivin by RNAi inhibits growth of human gastric carcinoma cells. World J Gastroenterol 2007; 13:1170–4.

27.

Zhang

, Expression of p-Akt and COX-2 in gastric adenocarcinomas and adenovirus mediated Aktl and COX-2 ShRNA suppresses SGC-7901 gastric adenocarcinoma and U251 glioma cell growth in vitro and in vivo. Technol Cancer Res Treat 2009; 8:467–78.

28.

Czyzewska

Guzińska-Ustymowicz

Lebelt

. Evaluation of proliferating markers Ki-67, PCNA in gastric cancers. Rocz Akad Med Bialymst 2004; 49:64–6.

29.

Cawston

Wilson

. Understanding the role of tissue degrading enzymes and their inhibitors in development and disease. Best Pract Res Clin Rheumatol 2006; 20:983–1002.

30.

Semba

Moriya

Kimura

Yamakawa

. Phosphorylated Akt/PKB controls cell growth and apoptosis in intraductal papillary-mucinous tumor and invasive ductal adenocarcinoma of the pancreas. Pancreas 2003; 26:250–7.

31.

Zhang

Kang

. Inhibitory effects of adenovirus mediated COX-2, Akt1 and PIK3R1 shRNA on the growth of malignant tumor cells in vitro and in vivo. Int J Oncol 2009; 35:583–91.