All eukaryotic cells respond to the accumulation of unfolded
proteins in the endoplasmic reticulum (ER) by signaling an adaptive pathway termed the unfolded protein response (UPR).
Glucose-regulated
protein (Grp) 78 is a
molecular chaperone involved in the UPR. The aim of this study was to detect
Grp78 expression in
lung cancer using immunohistochemical (IHC) staining, and also to evaluate the relationship between the
Grp78 expression level and the prognosis of patients with
lung cancer. We used immunohistochemistry to analyze the
protein expression of
Grp78 in
paraffin-embedded
tumor samples from 132 well-characterized
lung cancer patients and compared the expression level of
Grp78, clinical variables and survival outcome. A positive expression of
Grp78 was detected in the cytoplasm of
tumor cells in 88 of the 132 patients (66.7%) with
lung cancer. No significant difference was observed between the
Grp78 expression and the gender, age at operation, histological type, pathologic stage, pathologic T status, and pathologic N status.
Lung cancer patients with a positive
Grp78 expression tended to show a better prognosis than those with a negative
Grp78 expression. In addition, a multivariate analysis of the clinicopathologic characteristics of
lung cancer indicated a positive expression of
Grp78 to be a significant factor for predicting a favorable prognosis (p < 0.001, risk ratio = 2.35). A positive expression of
Grp78 may thus be a useful marker for predicting a favorable prognosis in patients undergoing a resection of
lung cancer. The ER stress pathway mediated by
Grp78 may therefore be responsible for controlling the growth of
lung cancer cells.