Yonago Acta medica 2006;49:9–17

Expression of phospho-Akt and PTEN Proteins Predicts
the Survival of Patients with Pancreatic Cancer
Yoshimi Ozaki-Ohgami, Akemi Iwamoto, Shizue Yoshioka, Shigeru Tatebe, Yasuaki
Hirooka and Masahide Ikeguchi
Division of Surgical Oncology, Department of Surgery, School of Medicine, Tottori University
Faculty of Medicine, Yonago 683-8504 Japan

The phosphatidylinositol-3 kinase (PI3K)-Akt signaling pathway is known to protect
a variety of cells from apoptosis. Phospho-Akt (p-Akt) can facilitate cell survival andinactivating pro-apoptotic proteins. The phosphatase and tensin homologue deleted
on chromosome ten (PTEN) is a natural biological inhibitor of p-Akt in the PI3K-Aktpathway. The relationship between the expressions of p-Akt and PTEN and pancreaticcancer is unknown. Here, we designed a study to clarify the prognostic signiﬁcance ofp-Akt and PTEN expression in patients with pancreatic cancer. Immunohistochemical analysis of p-Akt and PTEN protein was performed on 51 specimens of pancreaticcancer. The expression of p-Akt was detected in 32 patients (62.7%). The expressionof p-Akt was frequently detected in patients with advanced stage pancreatic cancer (P= 0.0233). Patients with p-Akt-positive tumors had signiﬁcantly worse prognoses thanthose with p-Akt-negative tumors (overall survival; 11.3% versus 25.7%). The expression of PTEN was detected in 26 patients (51.0%). Patients with PTEN-positive tumors
had signiﬁcantly better prognoses than those with PTEN-negative tumors (overall survival; 29.9% versus 0%). Patients with p-Akt-positive and PTEN-negative tumors had
signiﬁcantly worse prognoses than those with p-Akt-negative and PTEN-positive tumors(overall survival; 0% versus 39.1%). Multivariate analysis revealed that expression ofp-Akt was an independent prognostic factor as well as arterial invasion and lymph nodemetastasis. The expression of p-Akt and PTEN proteins determined by immunohistochemistry may be a new method for predicting the prognosis of patients with pancreaticcancer.
Key words: immunohistochemistry; pancreatic cancer; phosphatase and tensin homologue deleted on chromosome ten; phosphorylated-Akt

Patients with pancreatic cancer usually have poorprognoses because of high malignancy and resistance to most available chemotherapeutic agents
due to pancreatic cancer’s resistance to apoptotosis (Bardeesy and DePinho, 2002; Heinemann,2002; Shi et al., 2002). In addition, it is difﬁcult
to cure pancreatic cancer through surgical resec-tion because it easily invades adjacent tissue.
Therefore, a new therapeutic modality needs tobe investigated for treating pancreatic cancer.
Enhanced understanding of the signaling mechanisms that regulate pancreatic cancer cell growth
may provide important insights into more effective therapeutic strategies.

Abbreviations: p-Akt, phosphorylated-Akt; PI3K, phosphatidylinositol-3 kinase; PTEN, phosphatase and tensin homologue deleted on chromosome ten9

Yoshimi Ozaki-Ohgami et al.

in patients with pancreatic cancer.
The relationship between p-Akt and PTEN
expression in human pancreatic cancer is not yet
fully understood. Expression of p-Akt and PTEN
in pancreatic cancer has not been shown to predicttumor malignancy or prognosis. We hypothesisethat expression of p-Akt and PTEN may be a novel indicator of advanced stage pancreatic cancer
or patient prognosis. In the present study, expression of p-Akt and PTEN was immunohistochemically examined in 51 patients with pancreaticcancer, and the correlation between expression ofp-Akt and PTEN and clinicopathological features
was studied.

Akt consists of a family of highly conserved
serine/threonine kinases. These kinases are activated in response to a wide variety of growth factors through phosphatidylinositol-3 kinase (PI3K).
Phosphorylation of Akt, which is activated Akt, ispromoted by phosphatidylinositides converted by
PI3K products. Phosphorylated Akt (p-Akt) can
facilitate cell survival and inactivate pro-apoptotic
proteins such as Bad and caspase-9 (Datta et al.,
1997; Cardone et al., 1998). Recently, p-Akt has
been demonstrated as a major mediator of survival
signals in a variety of cells including cancer cells(Tang et al., 2001). To date, there have been a few
studies on the incidence of Akt activation in various tumors using archived pathologic specimens.
In colon cancer, Akt activation was observed inpatients in advanced clinicopathological stages ofthe disease (Itoh et al., 2002). In breast cancer,
Akt activation was frequently observed whilea worse prognosis was predicted in endocrinetreated patients (Perez-Tenorio and Stal, 2002).
Phosphoryklated-Akt by PI3K plays an important role in the biological behavior of pancreaticcancer and its inhibition may provide a meansof treatment against pancreatic cancer (Cheng etal., 1996; Franke et al., 1995; Hinemann, 2002).
However, there have been few studies on p-Akt inpatients with pancreatic cancer. The phosphataseand tensin homologue deleted on chromosometen (PTEN) is a tumor suppressor protein that
dephosphorylates inositol phospholipid intermediates of the PI3K pathway, inhibiting activationof downstream targets including Akt (Leslie andDownes, 2002). It has been suggested that theloss of PTEN activity causes enhanced cell proliferation, decreased apoptosis and increased tumor
angiogenesis (Stambolic et al., 1998; Zhong etal., 2000). Several groups have reported loss ofheterozygosity, mutation or deletion of the genein different cancers, including glioblastoma, prostate, lung and breast carcinomas. Altered expression of PTEN has also been detected in various
precancerous lesions (Li et al., 1997; McMenaminet al., 1999; Mutter et al., 2000; Perren et al.,1999). However, there have been few studies on
the role of PTEN as a suppressor of tumor growthMaterials and Methods
Patients
Fifty-one patients who underwent curative resection of primary pancreatic cancer from October
1984 to September 2001 were selected for thestudy. Patient age ranged from 39 to 80 years(average 65.2 years); 38 were male and 13 female.
The clinicopathological ﬁndings were determinedaccording to established Tumor-Node-Metastasis
criteria (Sobin and Wittekind, 2002). Surgically resected specimens were macroscopicallyexamined to determine tumor location, size andinvasion of blood vessels. Tissue samples were
fixed in 10% formalin and processed by paraffin embedding. Histological sections were cut,stained with hematoxylin and eosin and evaluatedby pathologists to determine the degree of histological differentiation, existence of lymph nodemetastasis and invasion of blood vessels. The
patients’ progress was followed up until February
2002. The follow-up periods for survivors ranged
from 2 to 127 months (median, 22.8 months) after
surgery.
Immunohistochemistry
For immunohistochemical analysis, the streptavidin-biotin method (Histofine SAB-PO kit;
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