The expression of glucocorticoid receptor in patients with small cell lung cancer with or without ectopic adrenocorticotropic hormone syndrome

Xiaobo Wang; Jing Ke; Zongwei Wang; Ying Feng; Mingzhu Hu; Nannan Wu; Dong Zhao

doi:10.4103/ed.ed_29_19

ORIGINAL ARTICLE

Year : 2019 | Volume : 4 | Issue : 4 | Page : 99-102

The expression of glucocorticoid receptor in patients with small cell lung cancer with or without ectopic adrenocorticotropic hormone syndrome

Xiaobo Wang¹, Jing Ke¹, Zongwei Wang¹, Ying Feng¹, Mingzhu Hu², Nannan Wu¹, Dong Zhao¹
¹ Beijing Key Laboratory of Diabetes Mellitus Prevention and Research, Department of Endocrinology, Beijing Luhe Hospital, Capital Medical University, Beijing, China
² Department of Pathology, Beijing Luhe Hospital, Capital Medical University, Beijing, China

Date of Submission	28-Aug-2019
Date of Decision	19-Nov-2019
Date of Acceptance	18-Dec-2019
Date of Web Publication	31-Dec-2019

Correspondence Address:
Dr. Dong Zhao
Department of Endocrinology, Beijing Key Laboratory of Diabetes Mellitus Prevention and Research, Beijing Luhe Hospital, Capital Medical University, Beijing 101149
China

Source of Support: None, Conflict of Interest: None

Check

DOI: 10.4103/ed.ed_29_19

Abstract

Purpose: Ectopic adrenocorticotropic hormone (ACTH)-secreting syndrome (EAS) is a relatively rare disease. EAS could not be inhibited by endogenous or exogenous glucocorticoid, which may be its most important characteristic. We aimed to explore the expression of glucocorticoid receptor (GR) in small cell lung cancer (SCLC) with or without EAS.
Materials and Methods: In this study, we first reported one patient with EAS caused by SCLC, and we examined the expression of ACTH and GR on pulmonary tissue in normal people and SCLC patients with or without EAS.
Results: Immunochemistry analysis showed that there was no obvious difference in the expression of GR in SCLC without EAS compared with normal people. While in the EAS patient, GR expression was absent in the tissue.
Conclusions: Therefore, our study found that lower expression of GR in small cell lung cancer (SCLC) with EAS, which may contribute to the no inhibition by endogenous or exogenous glucocorticoid.

Keywords: Ectopic adrenocorticotropic hormone syndrome, glucocorticoid receptor, small cell lung cancer

How to cite this article:
Wang X, Ke J, Wang Z, Feng Y, Hu M, Wu N, Zhao D. The expression of glucocorticoid receptor in patients with small cell lung cancer with or without ectopic adrenocorticotropic hormone syndrome. Environ Dis 2019;4:99-102

How to cite this URL:
Wang X, Ke J, Wang Z, Feng Y, Hu M, Wu N, Zhao D. The expression of glucocorticoid receptor in patients with small cell lung cancer with or without ectopic adrenocorticotropic hormone syndrome. Environ Dis [serial online] 2019 [cited 2023 Mar 27];4:99-102. Available from: http://www.environmentmed.org/text.asp?2019/4/4/99/274522

Introduction

Ectopic adrenocorticotropic hormone (ACTH)-secreting syndrome (EAS) is a relatively rare disease with an incidence of 1/million/year.^[1] EAS is reported to be associated with many malignant tumors.^[2] During recent years, several tumors such as small cell lung carcinoma (SCLC), neuroendocrine tumors, phaeochromocytomas, and medullary carcinoma of the thyroid have emerged as causes of EAS.^[3],[4] Clinically, the presentations of EAS are similar to Cushing disease and poses a diagnostic challenge in localization of the ACTH source. The manifestations of EAS include hypertension, edema, hypokalemia, weakness and abnormal glucose tolerance, and so on. Biochemical testing showed obviously increase in plasma ACTH and cortisol level, which could not be inhibited by endogenous or exogenous glucocorticoid.^[5]

Glucocorticoids, a class of stress-induced steroid hormones synthesized by the adrenal cortex, which is strictly under the control of the hypothalamic–pituitary–adrenal axis.^[6] Glucocorticoids in humans are known to regulate diverse cellular functions including development, homeostasis, metabolism, cognition, and inflammation. Endogenous glucocorticoid levels in the serum display a classic circadian pattern, peaking at the beginning of the period of the highest activity. High level of ectopic serum ACTH cannot be suppressed by endogenous or exogenous glucocorticoid, and this is the cardinal characteristic of EAS.

Glucocorticoids mediate their effect through intracellular glucocorticoid receptor (GR), which belongs to a large family of transcription factors known as the nuclear hormone receptors. It is well documented that the level of GR protein determines the magnitude of glucocorticoid response. Therefore, we aimed to explore the ACTH and GR expression in SCLC patients with or without EAS.

Materials and Methods

Ethical statement

The study was approved by Ethics Committee of Beijing Luhe Hospital. We collected pulmonary tissue from healthy, non-EAS-SCLC, EAS-SCLC patients.

Immunohistochemistry

The slice was dewaxed by xylene and re-watered by alcohol. Three percent H₂O₂ at room temperature for 10 min. The citric acid buffer was soaked at 100°C for 20 min. The first antibody was incubated in a refrigerator at 4°C overnight and washed by phosphate buffered solution (PBS) for 3 times. The second antibody was added dropwise, incubated at 37°C for 1 h, washed by PBS for 3 times, and 3, 3'-diaminobenzidine (DAB) developed color for 5 min. Hematoxylin was re-dyed for 2 min, then sealed and observed under the microscope.

Positive criteria

The semi-quantitative method was used, mainly according to the staining intensity, range, and number of positive cells. Weak positive: the number of positive cells is <30%; medium-strong positive: the number of positive cells is 30%–60%; and strong positive: the number of positive cells is more than 60%.

Results

The case and laboratory examinations

A 70-year-old female visited her primary care for worsening fatigue with lower limbs for more than 20 days. The patient has a history of more than 60 years of heavy smoking, 10 cigarettes per day. Laboratory testing as an outpatient revealed hypokalemia of 2.15 mmol/L (3.5–5.5 mmol/L). In addition, the patient showed increased blood pressure, blood glucose level, and hypoproteinemia. There was no history of diabetes mellitus or hypertension. The patient was then admitted to the hospital. The vitals were heart rate of 74 bpm, blood pressure of 144/66 mmHg, and respiratory rate of 18 bpm. Physical examination showed edema in the lower limbs; the rest of examination was within normal limits.

After admission, her hypokalemia was refractory, although continuous oral and intravenous potassium supplements. The 24-h urine potassium was high (97.53 mmol/L), suggesting renal loss. Serum ACTH level of 0 am, 8 am, and 4 pm was 328.79, 384.08, and 288.35 pg/ml, respectively. The serum cortisol level of 0 am, 8 am, and 4 pm was 64.38, 70.88, and 68.52 μg/dl, respectively. The 24-h urine-free cortisol level was 4,101.9 μg. Recumbent test: Renin-AII-ALD: 13.17–171.24–119.14 pg/ml; standing test: Renin-AII-ALD: 12.82–165.04–105.16 pg/ml. No obvious abnormality was observed in pituitary magnetic resonance imaging plain scan. Parathyroid ultrasonography showed a low echo nodule in the right parathyroid subgroup. Thyroid ultrasonography showed multiple nodules in the thyroid. Subsequent contrast enhanced computed tomography scan of the lung showed multiple enlarged lymph nodes in mediastinal and right lung portal areas. Density nodules of soft tissue under the pleural membrane of the lower right lung, pulmonary interstitial fibrosis, complicated with pulmonary infection, bilateral pleural hypertrophy, and arteriosclerosis. Neither low-dose nor high-dose dexamethasone test showed no inhibition of cortisol (>63.44 μg/dl). The metabolic findings, high ACTH level with radiologic and histological evidence, made ectopic ACTH syndrome from small cell lung cancer the most likely diagnosis. The primary laboratory results of the patient are summarized in [Table 1].

Table 1: Biochemical characteristics of the patient

Click here to view

Adrenocorticotropic hormone and glucocorticoid receptor expression in SCLC patients with or without ectopic adrenocorticotropic hormone syndrome

High-dose dexamethasone suppression test is well known to be an important test in the diagnosis of ectopic ACTH syndrome. We examined the ACTH and GR expression in SCLC patients with or without EAS. The pituitary gland tissue was also stained with ACTH and GR antibodies as a positive control. There was no difference in the ACTH and GR expression between control and SCLC patients without EAS [Figure 1]. Compared with control, ACTH expression obviously increased while GR expression reduced in the SCLC patient with EAS [Figure 2], suggesting the reduction of GR expression may contribute to the no inhibition of high-dose dexamethasone.

Figure 1: Adrenocorticotropic hormone and glucocorticoid receptor expression of pulmonary tissue in control and two nonectopic adrenocorticotropic hormone syndrome-SCLC patients. Labeling index (×100)

Click here to view

Figure 2: Adrenocorticotropic hormone and glucocorticoid receptor expression in pulmonary tissue in the ectopic adrenocorticotropic hormone syndrome-SCLC patient. Pituitarium tissue was as a positive control. Labeling index (×100)

Click here to view

Discussion

The anti-inflammatory and immunosuppressive effects of glucocorticoids are exploited extensively. Endogenous glucocorticoids are stress-induced hormones synthesized under the control of the hypothalamic–pituitary–adrenal axis. A high level of glucocorticoid could inhibit the secretion of ACTH, which is named as feedback. While the regulation is out of control in EAS, high-dose dexamethasone suppression test has been applied in the diagnosis of EAS based on the characteristic. However, the underlying mechanism is not clear. Multiple mechanisms have been proposed to explain the phenomenon. Reduced GR expression is thought to be an important factor in mediating glucocorticoid resistance.

The GR is a ubiquitously expressed protein, found in almost all human cell types and tissues at appreciable levels. It is well-established that the level of GR expression is closely correlated with the magnitude of the glucocorticoid response.^[7] Therefore, GR expression level may be an important determinant of the glucocorticoid response.^[8] Several studies have shown that reduced GR expression in primary acute lymphoblastic leukemia cells is associated with initial resistance to glucocorticoid therapy, relapse, and poor prognosis.^[9],[10] In such cell lines, including SLC cell lines, reduced GR expression was reported.^[8],[11] In our study, we collected pulmonary tissue from healthy, SCLC patients with or without EAS. Meanwhile, we collected tissue from pituitarium as a positive control. Immunochemistry analysis showed that there is no obvious difference in the expression of GR in SCLC patients without EAS compared with control group. While in SCLC patients with EAS, no obvious GR expression was seen in the pulmonary tissue. The results indicate that reduced GR expression may explain the no response to high-dose dexamethasone suppression test.

Several studies explored the mechanism of GR downregulation in cell lines. It is reported that glucocorticoid-induced downregulation of GR mRNA has been attributed to reduce transcription of the GR gene as well as decreased stability of the GR mRNA.^[12],[13] While no data available of GR expression of pulmonary tissue in the SCLC patient with EAS. Suggesting the reduction of GR expression may contribute to the no inhibition of high-dose dexamethasone. More samples are still needed to confirm the phenomenon, and further studies are needed to illuminate the mechanism of GR downregulation or absent.

Conclusions

In SCLC patients with EAS, the reduction of GR expression may contribute to the no inhibition of high-dose dexamethasone.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1.	Bhansali A, Walia R, Rana SS, Dutta P, Radotra BD, Khandelwal N, et al. Ectopic cushing's syndrome: Experience from a tertiary care centre. Indian J Med Res 2009;129:33-41. [PUBMED] [Full text]
2.	Alexandraki KI, Grossman AB. The ectopic ACTH syndrome. Rev Endocr Metab Disord 2010;11:117-26.
3.	Isidori AM, Kaltsas GA, Pozza C, Frajese V, Newell-Price J, Reznek RH, et al. The ectopic adrenocorticotropin syndrome: Clinical features, diagnosis, management, and long-term follow-up. J Clin Endocrinol Metab 2006;91:371-7.
4.	Hernández I, Espinosa-de-los-Monteros AL, Mendoza V, Cheng S, Molina M, Sosa E, et al. Ectopic ACTH-secreting syndrome: A single center experience report with a high prevalence of occult tumor. Arch Med Res 2006;37:976-80.
5.	Oldfield EH, Doppman JL, Nieman LK, Chrousos GP, Miller DL, Katz DA, et al. Petrosal sinus sampling with and without corticotropin-releasing hormone for the differential diagnosis of cushing's syndrome. N Engl J Med 1991;325:897-905.
6.	Rhen T, Cidlowski JA. Antiinflammatory action of glucocorticoids--new mechanisms for old drugs. N Engl J Med 2005;353:1711-23.
7.	Vanderbilt JN, Miesfeld R, Maler BA, Yamamoto KR. Intracellular receptor concentration limits glucocorticoid-dependent enhancer activity. Mol Endocrinol 1987;1:68-74.
8.	Gross KL, Lu NZ, Cidlowski JA. Molecular mechanisms regulating glucocorticoid sensitivity and resistance. Mol Cell Endocrinol 2009;300:7-16.
9.	Bloomfield CD, Smith KA, Peterson BA, Munck A. Glucocorticoid receptors in adult acute lymphoblastic leukemia. Cancer Res 1981;41:4857-60.
10.	Ramamoorthy S, Cidlowski JA. Ligand-induced repression of the glucocorticoid receptor gene is mediated by an NCoR1 repression complex formed by long-range chromatin interactions with intragenic glucocorticoid response elements. Mol Cell Biol 2013;33:1711-22.
11.	Wallace AD, Cao Y, Chandramouleeswaran S, Cidlowski JA. Lysine 419 targets human glucocorticoid receptor for proteasomal degradation. Steroids 2010;75:1016-23.
12.	Schaaf MJ, Cidlowski JA. AUUUA motifs in the 3'UTR of human glucocorticoid receptor alpha and beta mRNA destabilize mRNA and decrease receptor protein expression. Steroids 2002;67:627-36.
13.	Burnstein KL, Jewell CM, Cidlowski JA. Human glucocorticoid receptor cDNA contains sequences sufficient for receptor down-regulation. J Biol Chem 1990;265:7284-91.