Expression of aromatase CYP19 and its relationship with parameters in NSCLC

Exploring estrogenic activity in lung cancer

It is well known that a connection between xenobiotics inhalation, especially tobacco combustion and Lung Cancer development is strongly significant and indisputable. However, recent studies provide evidence indicating that another factors such as, estrogens are also involved in lung carcinoma biology and metabolism. Although the status of estrogen receptors (ER), in both cancerous and healthy lung tissue has been well documented, there is still inconclusive data with respect of which isoform of the receptor is present in the lungs. However according to several studies, ERβ appears to be predominant form. Apart from ERs, estrogens can work through a recently discovered G-coupled estrogen receptor. Binding with both types of the receptors causes a signal, which leads to i.e. enhanced cell proliferation. There are many published reports which suggest that estrogen can be synthesized in situ in lung cancer. Some disturbances in the activity and expression levels of enzymes involved in estrogen synthesis were proved. This suggests that increased amounts of sex-steroid hormones can affect cells biology and be the reason of the accelerated development and pathogenesis of lung cancer. There also exist phenomena which associate estrogenic metabolism and tobacco combustion and its carcinogenic influence on the lungs. Compounds present in cigarette smoke induce the activity of CYP1B1, the enzyme responsible for estrogenic metabolism and synthesis of their cateholic derivatives. These structures during their redox cycle are able to release reactive oxygen species or form DNA adduct, which generally leads to destruction of genetic material. This process may explain the synergistic effect of smoking and estrogens on estrogen-dependent lung cancer development.

Estrogen receptor 1 gene expression and its combination with estrogen receptor 2 or aromatase expression predicts survival in non-small cell lung cancer

The biological roles of estrogen receptor 1 (ERS1), estrogen receptor 2 (ERS2), and aromatase (CYP19A1) genes in the development of non-small cell lung cancer (NSCLC) is unclear, as is the use of their expression as a prognostic factor. The aim of this study was to investigate the prognostic value of estrogen receptors and aromatase mRNA expression, along with aromatase protein concentration, in resected NSCLC patients. Tumor and non-tumor lung tissue samples were analyzed for the mRNA expression of ERS1, ERS2 and CYP19A1 by RT-PCR. Aromatase concentration was measured with an ELISA. A total of 96 patients were included. ERS1 expression was significantly higher in non-tumor tissue than in tumor samples. Two gene expression categories were created for each gene (and protein): high and low. ERS1 high category showed increased overall survival (OS) when compared to the low expression category. Aromatase protein concentration was significantly higher in tumor samples. Higher ERS1 expression in tumor tissues was related to longer overall survival. The analysis of gene expression combinations provides evidence for longer OS when both ERS1 and ERS2 are highly expressed. ESR1, alone or in combination with ERS2 or CYP19A1, is the most determining prognostic factor within the analyzed 3 genes. It seems that ERS1 can play a role in NSCLC prognosis, alone or in combination with other genes such as ERS2 or Cyp19a1. ERS2 in combination with aromatase concentration could have a similar function.

Aromatase and estrogen receptor alpha mRNA expression as prognostic biomarkers in patients with astrocytomas

Estrogens are oncogenic hormones at a high level in breast, prostate, endometrial and lung cancer. Estrogens are synthesized by aromatase which has been used as a biomarker both in breast and lung cancer. Estrogen biological activities are executed by their classic receptors (ERα and ERβ). ERα has been described as a cancer promoter and ERβ, as a possible tumor suppressor. Both receptors are present at low levels in primary multiforme glioblastoma (GBM). The GBM frequency is 50 % higher in men than in women. The GBM patient survival period ranges from 7 to 18 months. The purpose of this pilot study was to evaluate aromatase and estrogen receptor expression, as well as 17ß-estradiol concentration in astrocytoma patients biopsies to obtain a prognosis biomarker for these patients. We analyzed 36 biopsies of astrocytoma patients with a different grade (I-IV) of malignity. Aromatase and estrogen receptor mRNA expression were analyzed by semiquantitative RT-PCR, and the E2 levels, by ELISA. E2 concentration was higher in GBM, compared to grade II or III astrocytomas. The number of cells immunoreactive to aromatase and estrogen receptors decreased as the grade of tumor malignity increased. Aromatase mRNA expression was present in all biopsies, regardless of malignity grade or patient age or gender. The highest expression of aromatase mRNA in GBM patients was associated to the worst survival prognostic (6.28 months). In contrast lowest expression of ERα mRNA in astrocytoma patients had a worst prognosis. In conclusion, aromatase and ERα expression could be used as prognosis biomarkers for astrocytoma patients.

Prognostic and therapeutic implications of aromatase expression in lung adenocarcinomas with EGFR mutations

PURPOSE

Lung adenocarcinomas among never-smokers are more common in females than in males. This implies that gender-dependent hormones promote smoking unrelated lung adenocarcinoma. We therefore investigated mRNA expression of aromatase, an intrinsic estrogen synthetase, in lung adenocarcinoma and assessed its correlation to clinicopathologic factors, including EGFR mutations and postsurgical prognosis.

EXPERIMENTAL DESIGN

Aromatase mRNA expression in primary tumor samples from 110 patients with lung adenocarcinoma was evaluated with qRT-PCR. Inhibitory effects of the aromatase inhibitor exemestane were assessed in lung adenocarcinoma cell lines (11-18 and HCC4006), which have EGFR mutations, separately and combined with EGFR tyrosine kinase inhibitor erlotinib.

RESULTS

Aromatase gene expression was not correlated with patients' clinicopathologic factors, including EGFR mutation status. High aromatase expression was associated with poor prognosis for both recurrence-free survival (P = 0.004) and overall survival (P = 0.003). In addition, the prognostic significance of aromatase expression was limited to females, never-smokers, and patients with EGFR mutations, but not in their counterparts. HCC4006, which has a low aromatase mRNA expression level, was not sensitive to exemestane, either alone or combined with erlotinib. In contrast, growth of 11-18 cells, which have high aromatase expression, was significantly inhibited by exemestane, both alone and combined with erlotinib.

CONCLUSIONS

Aromatase is a candidate prognostic factor in patients with lung adenocarcinoma, especially in those with EGFR mutations, and may also be a beneficial therapeutic target in those patients.

The role of estrogen, progesterone and aromatase in human non-small-cell lung cancer

Lung cancer is the leading cause of cancer-related deaths in both men and women worldwide. Despite advances in treatment, patients have few effective therapeutic options and survival rates remain low. Emerging evidence suggests that the hormones estrogen and progesterone play a key role in the progression of non-small-cell lung cancer (NSCLC). The aromatase enzyme, which is responsible for a key step in estrogen biosynthesis, elicits higher levels of estrogen in lung tumors as well as in metastases compared with nonmalignant tissues. Thus, aromatase may prove to be a key predictive biomarker for treatment of NSCLC. Epidemiologic and preclinical data show estrogens play a critical role in lung tumor development and progression. Two estrogen receptors, α and β, are expressed in normal and in cancerous lung epithelium, and estrogen promotes gene transcription that stimulates cell proliferation and inhibits cell death. Furthermore, expression of both forms of estrogen receptor, progesterone receptor and aromatase in NSCLC specimens has been correlated with worse clinical outcomes. Combination therapies that include estrogen receptor downregulators and aromatase inhibitors are currently being assessed in Phase I-II clinical trials among patients with advanced NSCLC. Results will help guide future lung cancer management decisions, with a goal of achieving more effective and less toxic treatments for patients.

Cytoplasmic estrogen receptor β as a potential marker in human non-small cell lung carcinoma

OBJECTIVES

Estrogen has been reported to promote an increased susceptibility to lung cancer development. This study focusses on the role of cytoplasmic estrogen receptor β (c-ERβ) in NSCLC.

METHODS

NSCLC (n = 162) cases were analyzed using immunohistochemistry (IHC) for c-ERβ expression and its association with clinicopathological variables. Significance of c-ERβ expression was further examined using in vitro studies in NSCLC cell lines.

RESULTS

Among ERβ and aromatase positive NSCLC females, c-ERβ was significantly associated with greater tumor diameter and tended to be associated with worse overall survival. A549 and LCAM1 cells expressed aromatase, as well as c-ERβ and nuclear ERβ (n-ERβ). U0126 (MAPK/extracellular-signal-regulated kinase (ERK) inhibitor) abrogated MAPK phosphorylation, caused by estradiol via c-ERβ, more effectively than ICI 182780 (ER blocker) in either cell line. However, ICI 182780 completely abrogated the estrogen responsive elements (ERE)-luciferase activity caused by estradiol. Combination therapy with ICI 182780 and U0126 turned out to be far more effective than either treatment alone in either A549 or LCAM1 cells.

CONCLUSION

The results indicated that ERβ may contribute to NSCLC via non-genomic action of estrogen through its cytoplasmic form, in addition to the genomic actions via n-ERβ. These actions of estrogen in NSCLCs may be abrogated by combination therapy with ICI 182780 and U0126.

Expression levels of estrogen receptor beta in conjunction with aromatase predict survival in non-small cell lung cancer

Estrogen signaling pathways may play a significant role in the pathogenesis of non-small cell lung cancers (NSCLC) as evidenced by the expression of aromatase and estrogen receptors (ERα and ERβ) in many of these tumors. Here we examine whether ERα and ERβ levels in conjunction with aromatase define patient groups with respect to survival outcomes and possible treatment regimens. Immunohistochemistry was performed on a high-density tissue microarray with resulting data and clinical information available for 377 patients. Patients were subdivided by gender, age and tumor histology, and survival data was determined using the Cox proportional hazards model and Kaplan-Meier curves. Neither ERα nor ERβ alone was predictor of survival in NSCLC. However, when coupled with aromatase expression, higher ERβ levels predicted worse survival in patients whose tumors expressed higher levels of aromatase. Although this finding was present in patients of both genders, it was especially pronounced in women ≥ 65 years old, where higher expression of both ERβ and aromatase indicated a markedly worse survival rate than that determined by aromatase alone. Expression of ERβ together with aromatase has predictive value for survival in different gender and age subgroups of NSCLC patients. This predictive value is stronger than each individual marker alone. Our results suggest treatment with aromatase inhibitors alone or combined with estrogen receptor modulators may be of benefit in some subpopulations of these patients.

Suppression of estrogen actions in human lung cancer

Estrogen plays a critical role in female reproduction but has also been reported to have important roles in various target tissues expressing estrogen receptor (ER) α and/or ERβ in both male and female. ERs especially ERβ have been demonstrated to be present and functional in both normal human lung and its disorders including cancer. Non-small cell lung carcinomas (NSCLCs) are well-known to be composed of heterogeneous groups. Squamous cell carcinoma is the most common subtype in men, but adenocarcinoma is the most common histologic subtype in women. Therefore, sex steroid hormones such as estrogens have been considered to play some roles in NSCLC. In particular, results of several epidemiological analyses pointed out the association between physiological or artificial alterations of hormone status such as menstruation and postmenopausal administration of hormone replacement therapy and lung cancer risks or its development especially in female subjects. In NSCLC tissues, intratumoral estrogen synthesis via aromatase, which is a key enzyme in the estrogen synthesis involved in aromatization of androgens into estrogens, has recently become of clinical interest as a possible target of therapy. Therefore, in this review, we focused on the potential of an endocrine therapy in NSCLC using clinically available inhibitors of estrogen and aromatase actions.

Aromatase in human lung carcinoma

Lung cancer is the leading cause of cancer mortality in both women and men worldwide but gender differences exist in their clinical and biological manifestations. In particular, among life time non-smoker, female are far more likely to develop lung carcinoma than male. Recent studies demonstrated that estrogens are synthesized in situ in both male and female lung cancers through aromatase, suggesting that sex steroid may contribute to the pathogenesis and development of lung carcinoma. In addition, human lung carcinomas have been recently demonstrated to be frequently associated with expression of estrogen receptors in both male and female patients and a lower expression of aromatase was reported to be associated with better prognosis. Preclinical studies further demonstrated that aromatase inhibitor (AI) suppressed the lung tumor growth both in vitro and in vivo. These findings all suggest a potential role of intratumoral aromatase in biological behavior of non-small cell lung cancer (NSCLC), the most common form of human lung malignancy. Therefore, AIs may become viable therapeutic options for disease management in NSCLC patients but further studies are definitely required to obtain a better understanding of the potential roles of intratumoral aromatase expression as a predictive biomarker for clinical outcome in these NSCLC patients.

Changes in aromatase (CYP19) gene promoter usage in non-small cell lung cancer

In humans, aromatase (CYP19) gene expression is regulated via alternative promoters. Activation of each promoter gives rise to a CYP19 mRNA species with a unique 5'-untranslated region. Inhibition of aromatase has been reported to downregulate lung tumor growth. The genetic basis for CYP19 gene expression and aromatase activity in lung cancer remains poorly understood. We analyzed tissues from 15 patients with non-small cell lung cancer (NSCLC) to evaluate CYP19 promoter usage and promoter-specific aromatase mRNA levels in NSCLC tumor tissues and adjacent non-malignant tissues. CYP19 promoter usage was determined by multiplex RT-PCR and aromatase mRNA levels were measured with real-time RT-PCR. In non-malignant tissues, aromatase mRNA was primarily derived from activation of CYP19 promoter I.4. Although promoter I.4 usage was also dominant in tumor tissues, I.4 activation was significantly lower compared with adjacent non-malignant tissues. Activity of promoters I.3, I.1 and I.7 was significantly higher in tumor tissues compared with non-malignant tissues. In 4 of 15 cases of non-small cell lung cancer, switching from CYP19 promoter I.4 to the alternative promoters II, I.1 or I.7 was observed. In 9 cases, there were significantly higher levels of aromatase mRNA in lung tumor tissues compared with adjacent non-malignant tissues. These findings suggest aberrant activation of alternative CYP19 promoters that may lead to upregulation of local aromatase expression in some cases of NSCLC. Further studies are needed to examine the impact of alternative CYP19 promoter usage on local estrogen levels and lung tumor growth.

Efficient expression of human aromatase (CYP19) in E. coli

Human aromatase (CYP19, P450arom) is responsible for the conversion of androgens to estrogens. In addition to the estrogen biosynthesis in gonads and adrenals in a classical endocrine manner, this enzyme is widely expressed in various tissues and locally regulates the estrogen level or estrogen/androgen ratio in an intracrine manner. Since estrogen biosynthesis is involved in many essential biological events in humans, aromatase is an attractive target for investigations in basic biomedical and pharmacological sciences. Aromatase is a membrane protein localized on the endoplasmic reticulum, and its instability and hydrophobic nature has hampered the investigation of this important biological system. To investigate the structure-function relationship of human aromatase by obtaining quantities of the purified enzyme, we have developed the expression system of human aromatase in E. coli. The human aromatase has two major forms from its genetic polymorphism, arginine (264R) and cysteine (264C) at the amino acid position 264. Although there is only one amino acid difference between the two forms of aromatase, the 264C form was expressed in E. coli with the cold stress response induced by chloramphenicol while the 264R form was expressed by the coexpression of heat shock proteins GroES/GroEL. In the case of human aromatase, a clear protocol is important to determine the expression levels by the reduced CO-difference spectrum. Therefore, the expression methods for the two forms of human aromatase as well as a method for the determination of the reduced CO-difference spectrum will be described.