ApoE plays a key role in various biological events. The aim of this study is to clarify its clinical significance in
gastric cancer. We obtained paired clinical bulk samples of
tumor tissue and corresponding normal tissue from 124
gastric cancer patients. To address
ApoE mRNA expression clearly, we selected four samples, and differentially dissected
gastric cancer and normal epithelium using
laser microdissection (LMD) system.
ApoE mRNA expression was examined by real-time reverse transcription (RT)-polymerase chain reaction (PCR).
ApoE protein expression was assessed by immnunohistochemistry. The relationship between
ApoE mRNA expression and clinicopathologic factors was statistically analyzed. RT-PCR assay for 124 bulk samples showed that
ApoE mRNA expression was more highly expressed in
gastric cancer tissue than in corresponding normal mucosa (p < 0.0001). By RT-PCR assay of four LMD samples,
ApoE mRNA was overexpressed in
gastric cancer. Immunohistochemistry showed that
ApoE was predominantly expressed in
gastric cancer.
Tumors with high
ApoE mRNA expression showed deeper
tumor invasion into the muscle layer (p < 0.0001), the serosal layer (p < 0.01), or more positive
lymph node metastasis (p < 0.05). When assessed by Kaplan-Meier analysis, patients with high
ApoE expression
tumor had a shorter survival than those with low
ApoE expression
tumor (p < 0.05). Moreover, multivariate analysis indicated that high
ApoE mRNA expression was an independent
indicator for muscular invasion (p < 0.01).
ApoE is highly expressed in
gastric cancer, contributing to shorter survival. In particular,
ApoE was closely correlated with muscular invasion, and may be a possible
biomarker predicting muscular invasion of
gastric cancer.