Estrogens are key signaling molecules that regulate various physiological processes such as cell growth, development, and differentiation. They also play a major role in many pathological conditions, such as
hormone-dependent
cancer. The importance of inhibiting
estrogen receptor signaling in diseases of
estrogen target tissues, such as
breast cancer, is well documented. However, the role of
estrogen signaling in diseases of nontarget tissues, such as
lung cancer, is not well characterized. The aim of the current study is to examine the expression of
estrogen receptor β (ERβ) and the roles of
estradiol (E2) and
fulvestrant on the progression of
lung cancer. Tissue microarray (TMA) and immunohistochemistry (IHC) analyses were used to detect the expression of
aromatase, ERα, and ERβ in 198 patients. We performed analyses to determine if there was any correlation among these three
proteins. A mouse model of
urethane-induced
lung adenocarcinoma was used in the study. Mice were divided into three treatment groups: blank control, E2 alone, and E2 +
fulvestrant (ERβ antagonist). Western blot analysis and fluorescence quantitative PCR (FQ-PCR) were used to measure expression of ERβ
protein and
mRNA levels, respectively. ERβ, but not ERα, was overexpressed in NSCLC samples.
Lung cancer progression in mice treated with E2 was significantly increased compared to either the control group or the E2 +
fulvestrant group. Mice in the E2 treatment group had significantly increased expression of ERβ at both the
mRNA and
protein levels compared to mice treated with E2 +
fulvestrant or control. Our data suggest that ERβ promotes
lung cancer progression in mice and that this progression can be inhibited with
fulvestrant. These findings may help elucidate the role of ERβ in
lung cancer and suggest that
estrogen receptor antagonists, such as
fulvestrant, may be therapeutically beneficial for the treatment of the disease.