Estrogen Receptor β Functions through Nongenomic Mechanisms in Lung Cancer Cells

Abstract

Recent studies have shown that estrogens promote the growth of lung cancer cells and may potentially be responsible for increased susceptibility to lung cancer in women. These observations raise the possibility of using antiestrogens in treating and preventing lung cancer. However, it is not clear how estrogen receptors (ERs) modulate the growth of non-small cell lung cancer (NSCLC) cells. Our Western blotting and real-time PCR analysis showed that NSCLC cells expressed ERbeta, but not ERalpha. In addition, ERbeta-specific ligands, but not ERalpha-specific ligands, promoted the growth of lung cancer cells. Furthermore, knockdown of ERbeta by short hairpin RNA constructs resulted in loss of estrogen-dependent growth of lung cancer cells. Interestingly, endogenous ERbeta failed to transcriptionally activate estrogen response element (ERE)-luciferase constructs in NSCLC cells, suggesting a lack of genomic function. Upon further investigation, ERbeta was found to be in the cytoplasm in all lung cancer cells and failed to translocate to the nucleus in the presence of estrogen, as observed by biochemical, ArrayScan, and confocal microscopy experiments. Nonetheless, estrogen caused rapid activation of cAMP, Akt, and MAPK signaling pathways in lung cancer cells. Immunohistochemical analysis of lung tumor biopsies showed strong ERbeta staining in the cytoplasm, whereas no staining was observed for ERalpha. In conclusion, our results suggest that that proliferative effects of estrogen in lung cancer cells is mediated primarily, if not exclusively, by the nongenomic action of ERbeta.

Preferential Estrogen Receptor β Ligands Reduce Bcl-2 Expression in Hormone-Resistant Breast Cancer Cells to Increase Autophagy

“…To verify that growth inhibition induced by L17 was mediated through the ERb, we treated LCC9 cells infected with a nontargeting retrovirus (shNT) or pSUPER-ERb shRNA (shERb; ref. 31) with L17 or vehicle. After 5 days, decreased proliferation was observed in L17-treated shNT-infected cells, while shERb expression completely prevented growth inhibition (Fig.…”

ERβ Regulates NSCLC Phenotypes by Controlling Oncogenic RAS Signaling

“…In addition to the protective function proposed in lung cancer, ERb1 is known to inhibit the growth of breast, ovarian, colon, and prostate cancer cells (6). Although treatment of NSCLC cells with ERb agonists has been reported to stimulate cell proliferation, the role of ERb in regulating cell survival and apoptosis in lung cancer still remains unclear (7,12).…”

“…However, the role of ERs in NSCLC remains poorly understood because previous studies produced contradictory data. Although two cell-based studies have reported an increased NSCLC cell proliferation in response to treatment with ERb ligands, clinical studies demonstrated a correlation between ERb positivity and better outcome of patients with lung cancer (7)(8)(9)(10)(11)(12). In particular, increased expression of wild-type ERb (ERb1) has been associated with better prognosis and reduced mortality and is inversely associated with lymph node metastases and tumor size in patients with NSCLC (11,13,14).…”

Non-nuclear activation of Signal transducer and activator of transcription 3 by 17β- estradiol in endometrial cancer cells

“…Endometrial adenocarcinoma cell line Ishikawa, which bears rich estrogen receptor(ER) [2], a kind gift from Professor Li-Hui Wei, Peking university, and HEC-1A cell line, which bears poor ER [2], obtained from ATCC (the American Type Culture Collection, Manassas, VA, USA) 5 months ago, were maintained in Phenol red-free RPMI 1640 or DMEM (Dulbecco's Modified Eagle Medium) medium, respectively, supplemented with 10% fetal calf serum (FCS), 100U/ml penicillin and 100μg/ml streptomycin and incubated with 5% CO2 at 37 °C. Cell line cultured in serumfree medium was cultured in RPMI 1640 or DMEM containing 0.5% the defined, estradiol-free and growth factor-free serum replacement (SR2, Sigma).Cells (5×10 5 or 1×10 6 ) were seeded in 25 cm 2 flasks (or 100mm plates) in Phenol red-free RPMI 1640 or DMEM containing 5% steroid-stripped FCS (DCC-FCS) (using dextran-coated charcoal) for 24 h. The medium was replaced with RPMI 1640 or DMEM containing 0.5% (v/v) DCC-FCS and after 48 h, the cells were washed and incubated in RPMI 1640 or DMEM containing 0.5% (v/v) SR2 for 24 h before stimulation. One micromolar water-soluble 17β-estradiol (estrogen, E2, Sigma Chemical Co.) was used for incubation at indicated time points (0min, 15min, 30min, 1 h, 2 h) to observe the optimal time for STAT3 activation.…”

“…Our former data demonstrated that 17β-estradiol, by non-nuclear action, can activate phosphatidylinositol 3-kinase (PI3K) /Akt signaling pathway in endometrial carcinoma cell lines [2] and blockage of PI3K/Akt pathway can antagonize estrogen-induced endometrial cancer proliferation [3]. Moreover, in breast cancer [4], lung cancer [5], colon cancer [6], and prostate cancer [7], mechanism of non-nuclear action is also involved.As we all know, Leptin as well as estrogen is closely associated with genesis and progression of endometrial carcinoma. Growth of malignant cells could be regulated by leptin-induced second messengers like STAT3 (signal transducers and activators of transcription 3).…”