Glucocorticoid receptors and growth inhibitory effects of dexamethasone in human lung cancer cell lines

Association of chronic obstructive pulmonary disease with risk of lung cancer in individuals aged 40 years and older: A cross-sectional study based on NHANES 2013-2018

BACKGROUND

It remains unclear whether chronic obstructive pulmonary disease (COPD) is an independent risk factor for lung cancer after excluding confounding factors such as smoking, age, sex, body mass index (BMI), comorbidities, etc.

METHODS

Data from 11,440 participants (≥ 40 years old) in the National Health and Nutrition Examination Survey (NHANES) 2013-2018 were analyzed. Weighted multivariable logistic regression models were used to assess the association between COPD and lung cancer risk. Subgroup analyses were based on age, sex, BMI, and smoking.

RESULTS

This study included 660 patients with COPD and 10,780 participants without COPD. The prevalence of lung cancer was significantly higher in patients with COPD compared to participants without COPD (3.39% vs 0.14%). After adjusting for confounding factors, COPD was associated with a significantly increased risk of lung cancer (OR, 12.24, 95% CI, 4.99-30.06, p < 0.001). This association remained significant in all subgroups, particularly in individuals aged > 65 years (OR, 20.05, 95% CI, 6.85-58.72, p < 0.001), smokers (OR, 19.38, 95% CI, 2.02-185.66, p = 0.010), males (OR, 17.39, 95% CI, 5.28-57.31, p < 0.001), individuals who quit smoking within 10 years (OR, 12.86, 95% CI, 2.59, 63.99, p = 0.002), and individuals with a BMI > 25 kg/m2 (OR, 14.56, 95% CI, 3.88-54.69, p < 0.001).

CONCLUSIONS

COPD is an independent risk factor for lung cancer, especially in certain subgroups. The combination of COPD and smoking greatly amplifies the lung cancer risk. These findings highlight the importance of early lung cancer screening in patients with COPD.

Glucocorticoid Receptor Signaling in NSCLC: Mechanistic Aspects and Therapeutic Perspectives

Recent advances in non-small cell lung cancer (NSCLC) biology and the discovery of novel therapeutic targets have led to the development of new pharmacological agents that may improve the clinical outcome of patients with NSCLC. The glucocorticoid receptor (GR) is an evolutionarily conserved protein belonging to the nuclear receptor superfamily of transcription factors and mediates the diverse actions of glucocorticoids in cells. Data suggest that the GR may play a relevant role in the molecular mechanisms of NSCLC tumorigenesis and malignant progression. Additionally, evidence indicates that glucocorticoids may affect the efficacy of standard treatment, including chemotherapy, immune checkpoint inhibitors, and targeted therapy. Furthermore, several findings show that GR expression may probably be associated with NSCLC patient survival. Finally, glucocorticoids may be used as therapeutic agents for the clinical management of NSCLC patients. Here, we briefly review the latest advances on the biological role of GR signaling in NSCLC and discuss the potential use of the GR as a prognostic and predictive biomarker. Importantly, we explore the therapeutic potential of glucocorticoids and the effect of adding such drugs to standard therapies for NSCLC.

Dexamethasone as an anti-cancer or hepatotoxic

The linkage between inflammation and oxidative stress in liver damage has been proven and is undeniable; dexamethasone with some antioxidants can reduce the toxicity of liver tissue. Due to the importance of cancer treatment, glucocorticoids' synergistic effect in inhibiting cancer cell growth is also investigated. Dexamethasone alone and combined with etoposide were tested at concentrations of 1, 5, and 10 μM to evaluate the potency of dexamethasone in inhibiting the growth of A549 cells using oxidative stress factors and DNA damage. Also, intraperitoneal injection of dexamethasone in rats was used to induce liver toxicity. Coenzyme Q10 at different concentrations (1, 10, and 50 mg/kg) was used as an antioxidant to assess the oxidative stress factors and measure Caspase-3 activity. The results showed that dexamethasone combined with etoposide could significantly inhibit the growth of cancer cells and induce apoptosis. Treatment of A549 cells using dexamethasone also inhibits cancer cells' growth by inducing oxidative stress and DNA damage. Dexamethasone also, by inducing oxidative stress and activation of caspase 3, ultimately causes hepatotoxicity. Treatment with different concentrations of CoQ10 showed improved mitochondrial function, antioxidant defense, and liver enzyme. The best effect of coenzyme Q10 on dexamethasone-induced hepatotoxicity is 50 mg/kg. As a result, dexamethasone (alone and combined with etoposide) has an anti-cancer effect by damaging DNA and inducing oxidative stress. Also, CoQ10 has antioxidant effects against dexamethasone-induced hepatotoxicity by improving mitochondrial function and reducing caspase-3 activity.

Targeting Nuclear Receptors in Lung Cancer—Novel Therapeutic Prospects

Lung cancer, the second most commonly diagnosed cancer, is the major cause of fatalities worldwide for both men and women, with an estimated 2.2 million new incidences and 1.8 million deaths, according to GLOBOCAN 2020. Although various risk factors for lung cancer pathogenesis have been reported, controlling smoking alone has a significant value as a preventive measure. In spite of decades of extensive research, mechanistic cues and targets need to be profoundly explored to develop potential diagnostics, treatments, and reliable therapies for this disease. Nuclear receptors (NRs) function as transcription factors that control diverse biological processes such as cell growth, differentiation, development, and metabolism. The aberrant expression of NRs has been involved in a variety of disorders, including cancer. Deregulation of distinct NRs in lung cancer has been associated with numerous events, including mutations, epigenetic modifications, and different signaling cascades. Substantial efforts have been made to develop several small molecules as agonists or antagonists directed to target specific NRs for inhibiting tumor cell growth, migration, and invasion and inducing apoptosis in lung cancer, which makes NRs promising candidates for reliable lung cancer therapeutics. The current work focuses on the importance of various NRs in the development and progression of lung cancer and highlights the different small molecules (e.g., agonist or antagonist) that influence NR expression, with the goal of establishing them as viable therapeutics to combat lung cancer.

Glucocorticoid receptor triggers a reversible drug-tolerant dormancy state with acquired therapeutic vulnerabilities in lung cancer

The glucocorticoid receptor (GR) regulates gene expression, governing aspects of homeostasis, but is also involved in cancer. Pharmacological GR activation is frequently used to alleviate therapy-related side-effects. While prior studies have shown GR activation might also have anti-proliferative action on tumours, the underpinnings of glucocorticoid action and its direct effectors in non-lymphoid solid cancers remain elusive. Here, we study the mechanisms of glucocorticoid response, focusing on lung cancer. We show that GR activation induces reversible cancer cell dormancy characterised by anticancer drug tolerance, and activation of growth factor survival signalling accompanied by vulnerability to inhibitors. GR-induced dormancy is dependent on a single GR-target gene, CDKN1C, regulated through chromatin looping of a GR-occupied upstream distal enhancer in a SWI/SNF-dependent fashion. These insights illustrate the importance of GR signalling in non-lymphoid solid cancer biology, particularly in lung cancer, and warrant caution for use of glucocorticoids in treatment of anticancer therapy related side-effects.

Pre-established Chromatin Interactions Mediate the Genomic Response to Glucocorticoids

The glucocorticoid receptor (GR) is a hormone-inducible transcription factor involved in metabolic and anti-inflammatory gene expression responses. To investigate what controls interactions between GR binding sites and their target genes, we used in situ Hi-C to generate high-resolution, genome-wide maps of chromatin interactions before and after glucocorticoid treatment. We found that GR binding to the genome typically does not cause new chromatin interactions to target genes but instead acts through chromatin interactions that already exist prior to hormone treatment. Both glucocorticoid-induced and glucocorticoid-repressed genes increased interactions with distal GR binding sites. In addition, while glucocorticoid-induced genes increased interactions with transcriptionally active chromosome compartments, glucocorticoid-repressed genes increased interactions with transcriptionally silent compartments. Lastly, while the architectural DNA-binding proteins CTCF and RAD21 were bound to most chromatin interactions, we found that glucocorticoid-responsive chromatin interactions were depleted for CTCF binding but enriched for RAD21. Together, these findings offer new insights into the mechanisms underlying GC-mediated gene activation and repression.

Inhaled corticosteroids have a protective effect against lung cancer in female patients with chronic obstructive pulmonary disease: a nationwide population-based cohort study

Whether the use of inhaled corticosteroids (ICS) protects patients with chronic obstructive pulmonary disease (COPD) from lung cancer remains undetermined. In this retrospective nationwide population-based cohort study, we extracted data of 13,686 female COPD patients (ICS users, n = 1,290, ICS non-users, n = 12,396) diagnosed between 1997 and 2009 from the Taiwan's National Health Insurance database. These patients were followed-up until 2011, and lung cancer incidence was determined. Cox regression analysis was used to estimate hazard ratios (HRs) for lung cancer incidence. The time to lung cancer diagnosis was significantly different between ICS users and non-users (10.75 vs. 9.68 years, P < 0.001). Per 100,000 person-years, the lung cancer incidence rate was 235.92 for non-users and 158.67 for users [HR = 0.70 (95% confidence interval {CI}: 0.46-1.09)]. After adjusting for patients' age, income, and comorbidities, a cumulative ICS dose > 39.48 mg was significantly associated with a lower risk of lung cancer [ICS users > 39.48 mg, HR = 0.45 (95% CI: 0.21-0.96)]. Age ≥ 60 years, pneumonia, diabetes mellitus, and hypertension decreased lung cancer risk, whereas pulmonary tuberculosis increased the risk. Our results suggest that ICS have a potential role in lung cancer prevention among female COPD patients.

Glucocorticoid receptor beta increases migration of human bladder cancer cells

Bladder cancer is observed worldwide having been associated with a host of environmental and lifestyle risk factors. Recent investigations on anti-inflammatory glucocorticoid signaling point to a pathway that may impact bladder cancer. Here we show an inverse effect on the glucocorticoid receptor (GR) isoform signaling that may lead to bladder cancer. We found similar GRα expression levels in the transitional uroepithelial cancer cell lines T24 and UMUC-3. However, the T24 cells showed a significant (p < 0.05) increased expression of GRβ compared to UMUC-3, which also correlated with higher migration rates. Knockdown of GRβ in the T24 cells resulted in a decreased migration rate. Mutational analysis of the 3' untranslated region (UTR) of human GRβ revealed that miR144 might positively regulate expression. Indeed, overexpression of miR144 increased GRβ by 3.8 fold. In addition, miR144 and GRβ were upregulated during migration. We used a peptide nucleic acid conjugated to a cell penetrating-peptide (Sweet-P) to block the binding site for miR144 in the 3'UTR of GRβ. Sweet-P effectively prevented miR144 actions and decreased GRβ expression, as well as the migration of the T24 human bladder cancer cells. Therefore, GRβ may have a significant role in bladder cancer, and possibly serve as a therapeutic target for the disease.

Glucocorticoid receptors in lung cancer: new perspectives

Proper expression of the glucocorticoid receptor (GR) plays an essential role in the development of the lung. GR expression and signalling in the lung is manipulated by administration of synthetic glucocorticoids (Gcs) for the treatment of neonatal, childhood and adult lung diseases. In lung cancers, Gcs are also commonly used as co-treatment during chemotherapy. This review summarises the effect of Gc monotherapy and co-therapy on lung cancers in vitro, in mouse models of lung cancer, in xenograft, ex vivo and in vivo The disparity between the effects of pre-clinical and in vivo Gc therapy is commented on in light of the recent discovery of GR as a novel tumour suppressor gene.

Minireview: Familiar Faces in Unfamiliar Places: The Emerging Role of Nuclear Receptors in Lung Cancer

Nuclear hormone receptors (NRs) are a superfamily of 48 transcription factors that are frequently modulated by ligands and control various cancer-relevant cellular pathways, such as differentiation, proliferation, migration, and metabolism. These properties make them excellent therapeutic targets in cancers dependent upon their activity, and as such, 3 NRs, estrogen receptor-α, androgen receptor, and retinoic acid receptor-α (more specifically, the promyelocytic leukemia-retinoic acid receptor-α translocation), have been targeted clinically in breast cancer, prostate cancer, and acute promyelocytic leukemia, respectively. Recently, a number of studies have highlighted a putative role for NRs in nonsmall cell lung cancer (NSCLC), a highly lethal type of lung cancer with relatively few targeted agents. Here, we review the potential roles of selected NRs in NSCLC and offer insights on how NRs may be leveraged in NSCLC to improve patient outcomes.

Glucocorticoid receptor over-expression promotes human small cell lung cancer apoptosis in vivo and thereby slows tumor growth

Small cell lung cancer (SCLC) is an aggressive tumor, associated with ectopic ACTH syndrome. We have shown that SCLC cells are glucocorticoid receptor (GR) deficient, and that restoration of GR expression confers glucocorticoid sensitivity and induces apoptosis in vitro. To determine the effects of GR expression in vivo, we characterized a mouse SCLC xenograft model that secretes ACTH precursor peptides, and so drives high circulating corticosterone concentrations (analogous to the ectopic ACTH syndrome). Infection of SCLC xenografts with GR-expressing adenovirus significantly slowed tumor growth compared with control virus infection. Time to fourfold initial tumor volume increased from a median of 9 days to 16 days (P=0.05; n=7 per group). Post-mortem analysis of GR-expressing tumors revealed a threefold increase in apoptotic (TUNEL positive) cells (P<0.01). Infection with the GR-expressing adenovirus caused a significant reduction in Bcl-2 and Bcl-xL transcripts. Furthermore, in both the GR-expressing adenovirus-infected cells and tumors, a significant number of uninfected cells underwent apoptosis, supporting a bystander cell killing effect. Therefore, GR expression is pro-apoptotic for human SCLCs in vivo, as well as in vitro, suggesting that loss of GR confers a survival advantage to SCLCs.

Preventive effects of bexarotene and budesonide in a genetically engineered mouse model of small cell lung cancer

In the present study, we examined the effect of bexarotene (Targretin) and budesonide in the chemoprevention of small cell lung carcinoma using a lung-specific knockout model of Rb1 and p53. Upon treatment with bexarotene, tumor incidence, number, and load were significantly reduced (P < 0.05). Budesonide treatment trended to inhibition, but the effect was not statistically significant (P > 0.05). Immunohistochemical staining indicated that bexarotene treatment decreased cell proliferation and increased apoptosis in tumors. The Rb1/p53 gene-targeted mouse seems to be a valuable model for chemopreventive studies on human small cell lung cancer. Our results indicate that the retinoid X receptor agonist bexarotene may be a potent chemopreventive agent in this cancer type.

Dexamethasone enhances trichosanthin-induced apoptosis in the HepG2 hepatoma cell line

AIMS

Trichosanthin (TCS) is a type I ribosome-inactivating protein (RIP) with antitumor activities for various cancers. In this paper, we aimed to investigate whether dexamethasone, an important synthetic member of the glucocorticoid steroids, in combination with TCS can be a potential therapy in treating hepatoma.

MAIN METHODS

Cell viability was investigated using MTT assay, and apoptosis was evaluated with Hoechst 33258 staining. Western blot analysis was used to examine the changes in the expression levels of IkappaB-alpha, NF-kappaB p65 subunit and Cox-2. Additionally, we took advantage of dominant-negative IkappaB (IkappaB-DM) over-expression and chemical inhibitor PDTC to inhibit NF-kappaB activation.

KEY FINDINGS

Our results demonstrated that dexamethasone could enhance TCS-induced apoptosis in the hepatoma cell line HepG2, decreasing IC50 values from in excess of 200microg/ml to 50microg/ml. In addition, our results demonstrated that TCS could induce rapid degradation of IkappaB-alpha, nuclear translocation of NF-kappaB and decrease of COX-2 expression in HepG2 cells. Inhibition of NF-kappaB by biological (IkappaB-DM) or chemical inhibitor (PDTC) increased HepG2 cells' sensitivity to TCS, resulting in cell viability rate decreasing and apoptotic rate increasing. Simultaneously, dexamethasone increased the level of IkappaB-alpha protein and effectively inhibited TCS-induced degradation of IkappaB-alpha.

SIGNIFICANCE

These results suggest that dexamethasone could enhance trichosanthin-induced apoptosis in the HepG2, at least in part, by inhibiting the NF-kappaB signaling pathway and thus strengthening the antitumor effects of TCS, which highlights the possibility of combined drug application of TCS and dexamethasone in the clinical treatment of hepatoma.

High‐dose, short‐term, anti‐inflammatory treatment with dexamethasone reduces growth and augments the effects of 5‐fluorouracil on dimethyl‐α‐benzanthracene‐induced mammary tumors in rats

OBJECTIVE

To evaluate the effects of dexamethasone (DXM) alone or in combination with 5-fluorouracil (5-FU) on dimethyl-alpha-benzanthracene (DMBA)-induced mammary tumors in rats.

MATERIAL AND METHODS

Female Sprague-Dawley rats were divided into 4 groups receiving: 1) saline (controls), 2) DXM (3 mg/kg), 3) 5-FU (1.5 mg/kg) and 4) DXM and 5-FU combined. The drugs were given i.p. every day for 4 days. Interstitial fluid pressure (Pif) and tumor growth were determined in all tumors on days 1, 5 and 7 using the "wick-in-the needle" technique and by external size measurements, respectively. Vessel density and inflammatory cell infiltration of tumor tissue were analyzed by immunohistochemistry.

RESULTS

DXM treatment significantly retarded tumor growth and reduced Pif. Treatment with a combination of DXM and 5-FU reduced tumor size significantly more than any of the agents alone (p<0.01-0.001). Enhanced uptake of 5-FU by DXM treatment was demonstrated by microdialysis. There were no differences in the density of CD31-positive vessels after DXM or 5-FU treatment, but inflammatory cell infiltration of tumor tissue was significantly reduced after DXM treatment.

CONCLUSIONS

Our data suggest that DXM may be beneficial as an adjuvant to chemotherapy in the treatment of mammary cancer by increasing the uptake of 5-FU in the tumor.

Overexpression of glucocorticoid receptor in human pancreatic cancer and in xenografts. An immunohistochemical study

Glucocorticoid receptor overexpression has been reported in a variety of human solid tumors, but much less in known about its presence in pancreatic cancer. Only one report is available in the literature, back to 1994, since that no peculiar attention has been paid to this issue. Immunohistochemical analysis of paraffin-embedded tissue sections was performed in human normal pancreata and well differentiated pancreatic adenocarcinomas (monoclonal primary antibody, ABCAM, Cambridge, UK). As positive control invasive ductal adenocarcinoma of the breast was used. In the normal non-tumorous pancreas a strong positivity was detected in all acinar cells, typically in the cytoplasm. Nuclear staining was not visible. The distribution of the positive reaction was homogenous. The ductal pancreatic carcinoma cells also displayed a strong positivity. The location of the immune reaction was mainly cytoplasmic but in some tumors a strong nuclear reaction was also noticed. In some slides acini remained also positive in the close vicinity of the tumor. Although the positivity of the ductal tumor cells was a constant finding in our samples, surprisingly, the liver metastasis was completely negative. Strong glucocorticoid receptor expression was also found in xenografted human pancreatic cancer showing a diffuse, mainly cytoplasmic positivity. Our studies have shown that the human pancreatic carcinomas do overexpress a strong glucocorticoid receptor positivity, but its significance is not clear. However, this finding might have a clinical relevance.

Glucocorticoid-mediated apoptosis resistance of solid tumors

More than a quarter of a century ago, the phenomenon of glucocorticoid-induced apoptosis in the majority of hematological cells was first recognized. More recently, glucocorticoid-induced antiapoptotic signaling associated with apoptosis resistance towards cytotoxic therapy has been identified in cells of epithelial origin, most of malignant solid tumors and some other tissues. Despite these huge amounts of data demonstrating differential pro- and anti-apoptotic effects of glucocorticoids, the underlying mechanisms of cell type-specific glucocorticoid signaling are just beginning to be described. This review summarizes our present understanding of cell type-specific pro- and anti-apoptotic signaling induced by glucocorticoids. We shortly introduce mechanisms of glucocorticoid resistance of hematological cells. We highlight and discuss the emerging molecular evidence of a general induction of survival signaling in epithelial cells and carcinoma cells by glucocorticoids. We give a summary of our current knowledge of decreased proliferation rates in response to glucocorticoid pre- and combination treatment, which are suspicious to be involved not only in protection of normal tissues, but also in protection of solid tumors from cytotoxic effects of anticancer agents.

Identification and functional analysis of SKA2 interaction with the glucocorticoid receptor

Glucocorticoid (GC) receptors (GRs) have profound anti-survival effects on human small cell lung cancer (SCLC). To explore the basis of these effects, protein partners for GRs were sought using a yeast two-hybrid screen. We discovered a novel gene, FAM33A, subsequently identified as a SKA1 partner and involved in mitosis, and so renamed Ska2. We produced an anti-peptide antibody that specifically recognized full-length human SKA2 to measure expression in human cell lines and tissues. There was a wide variation in expression across multiple cell lines, but none was detected in the liver cell line HepG2. A xenograft model of human SCLC had intense staining and archival tissue revealed SKA2 in several human lung and breast tumours. SKA2 was found in the cytoplasm, where it co-localized with GR, but nuclear expression of SKA2 was seen in breast tumours. SKA2 overexpression increased GC transactivation in HepG2 cells while SKA2 knockdown in A549 human lung epithelial cells decreased transactivation and prevented dexamethasone inhibition of proliferation. GC treatment decreased SKA2 protein levels in A549 cells, as did Staurosporine, phorbol ester and trichostatin A; all agents that inhibit cell proliferation. Overexpression of SKA2 potentiated the proliferative response to IGF-I exposure, and knockdown with shRNA caused cells to arrest in mitosis. SKA2 has recently been identified in HeLa S3 cells as part of a complex, which is critical for spindle checkpoint silencing and exit from mitosis. Our new data show involvement in cell proliferation and GC signalling, with implications for understanding how GCs impact on cell fate.

Glucocorticoid receptor overexpression exerts an antisurvival effect on human small cell lung cancer cells

Small cell lung cancer (SCLC) is an aggressive tumour with an abysmal prognosis. These cancers are characteristically resistant to glucocorticoid (Gc) action, owing to impaired expression of the glucocorticoid receptor (GR). We identified reduced GR expression in human SCLC cell lines, compared to a non-SCLC cell line. The SCLC cells also showed no Gc inhibition of proliferation, in contrast to non-SCLC cells. Retroviral overexpression of GR resulted in significantly increased cell death, which was partially blocked by the GR antagonist, RU486. Indeed, in cells sorted for GR expression, there was rapid, near complete loss of live cells by 72 h, in contrast to control cells that proliferated as expected. Flow cytometry using Annexin V revealed that cell death was by apoptosis. In addition, confocal analysis of fixed cells showed that cells overexpressing GR displayed a significant increase in fragmenting apoptotic nuclei. Microarray studies showed that transgenic GR expression upregulated the proapoptotic genes, BAD and BAX. We have, therefore, identified a profound apoptotic effect of GR in SCLC cells, which may explain the low levels of endogenous GR in SCLC cells. Understanding how GR overexpression leads to apoptotic cell death in SCLC cells may uncover new therapeutic strategies.

Expression and significance of glucocorticoid receptor alpha in meningiomas

OBJECTIVE

To explore the expression of the glucocorticoid receptor alpha (GRalpha) and its significance in the occurrence and progress of meningiomas.

MATERIALS AND METHODS

By the use of flow cytometry, the proliferative index (PI), S-phase fraction (SPF) and DNA ploidy were detected to evaluate the proliferation of tumor cells in 58 meningioma specimens. The expressions of GRalpha in all meningiomas and seven normal dura samples were studied by means of reverse transcription-polymerase chain reaction to compare the difference in GRalpha between meningiomas and normal dura. The relation between GRalpha and histological grades, PI, SPF and DNA ploidy were also analyzed.

RESULTS

The mean PI was 9.32%+/-4.41% while the mean SPF was 2.79%+/-2.43% in 58 meningioma specimens. DNA was diploid in 51 cases and aneuploid in the remaining seven cases, with the aneuploid rate being 12.1%. Nine of 58 meningiomas were GRalpha- negative and the rest were GRalpha-positive with a GRalpha-positive rate of 84.5%. The GRalpha-positive meningiomas included 13 '+', 15 '++', 9 '+++' and 12 '++++'. GRalpha was negative in normal dura samples. The GRalpha-positive rate of meningiomas was significantly greater than that of normal dura. There were no significant differences in PI and SPF among GRalpha-negative, GRalpha-weak positive and GRalpha-strong positive meningiomas. The difference in aneuploid rate between GRalpha-positive and GRalpha-negative meningiomas was also not significant.

CONCLUSION

GRalpha is of significance in meningiomas, which are a target tissue for glucocorticoid. However, GRalpha's expression had no obvious effect on the proliferative activity of meningiomas, so it may not be a major control of this process.

5-Aminolevulinic acid-induced fluorescence in bronchial tumours: dependency on the patterns of tumour invasion

5-ALA-induced protoporphyrin IX (PPIX) fluorescence kinetics was quantified by fluorescence microscopy in three-dimensional organ co-cultures of human bronchial epithelium, which were infiltrated by four different lung tumour cell lines (EPLC-M31, LCLC-103H, NCI-H125 and NCI-H841). Corresponding fluorescence measurements were performed in monolayer cultures of these tumour cell lines and BEAS-2B cells as a model for normal bronchial epithelium by flow cytometry. Significant differences of fluorescence intensities (FI) between the tumours were detected in organ co-cultures as well as in single cell measurements. Relative FI values in organ co-cultures (FI(EPLC-32M1)>FI(LCLC-H103)>FI(NCI-H125)>FI(NCI-H841)) did not correspond to the measurements in single cells (FI(LCLC-H103)>FI(NCI-H125)>FI(NCI-H841)>FI(EPLC-32M1)). Histology of organ co-cultures revealed different patterns of invasion and tumour cell densities depending on the tumour type. After correction of FI in the co-cultures to tumour cell density the correlation coefficient for fluorescence values between both models increased considerably. Thus, additionally to distinctive features of 5-ALA metabolism, patterns of tumour invasion may be a factor determining 5-ALA-induced fluorescence. Considering these results, a pronounced heterogeneity of 5-ALA-induced fluorescence might be expected in different bronchial tumours in vivo. This could interfere with the diagnostic reliability of 5-ALA-induced fluorescence for early tumour detection.

Dexamethasone regulation of gastrin-releasing peptide receptor in human lung cells

We investigated the effects of the glucocorticoid, dexamethasone (Dex), on expression of the gastrin-releasing peptide (GRP) receptor by human small cell lung carcinoma (SCLC) SHP77 cells. After 12h of 10nM Dex exposure, a six-fold increase in the peak of GRP receptor mRNA compared with untreated controls (10.5+/-4 versus 1.65+/-0.15 attomols/microg total RNA, respectively, P<0.05) occurred. GRP receptor mRNA levels fell to less than 0.5 attomols/microg total RNA after 24h; in Dex-treated cells, these levels rose to 1.2 compared with 0.12 attomols/microg total RNA in the absence of Dex after 7 days. A significant increase (P<0.05) in the GRP receptor-specific binding was also found. Stimulation of SHP77 cell proliferation (25-35% in the presence of 10-100 nM Dex; P<0.0001) was observed after 4-8 days of exposure; this stimulation was inhibited by GRP receptor antagonists. SHP77 cell content and concentration of bombesin-like peptides (BLP) in conditioned medium (approximately 4 nM) was unchanged by Dex. Stimulation of human SCLC SHP77 cell proliferation by Dex may, in part, occur via effects on the GRP autocrine system in these cells.

Glucocorticoids inhibit lung cancer cell growth through both the extracellular signal-related kinase pathway and cell cycle regulators

Glucocorticoids inhibit the proliferation of various cell types, but the mechanism of this inhibition remains unclear. We investigated the effect of dexamethasone on non-small cell lung cancer cell growth and cell cycle progression. We showed that dexamethasone suppresses the proliferation of A549 and Calu-1 cells, with accumulation of cells in G1/G0 stage of the cell cycle, as determined by fluorescence-activated cell sorter analysis. Western blot analysis confirmed that this is associated with hypophosphorylation of retinoblastoma protein. Using Western blot analysis and in vitro kinase assays, we found that dexamethasone results in decreased activity of CDK2 and 4, decreased levels of cyclin D, E2F, and Myc, and increased levels of the CDK inhibitor p21(Cip1). In addition, we found that dexamethasone decreases activity of extracellular signal-related kinase (ERK)/mitogen-activated protein kinase (MAPK). The kinetics of all these changes indicate that inhibition of the ERK/MAPK pathway precedes the cell cycle effects, suggesting that regulation of this MAPK-signaling pathway may be an alternative mechanism for glucocorticoid-induced cell cycle arrest and growth inhibition.

In vivo inhibition of tumour growth by dexamethasone in murine osteosarcomas

This study was performed to determine whether glucocorticoid (GC) is an effective inhibitor of tumour growth in murine osteosarcoma (OS) in vivo. The effects of dexamethasone (DEX) on the growth of this tumour were studied in male C3H/He mice. The animals received a dose of 1.25 or 5 microg/g of DEX in 0.1 ml of steroid solution daily intraperitoneally (i.p.) for 14 days. In each DEX-treated group, significant inhibition of the tumour growth curve was seen in a dose- dependent manner compared with the control group (P<0.0001). The percentage of proliferative cell nuclear antigen (PCNA)-positive cells was 22.7% in the 5 microg/g DEX treatment group compared with 67.6% in the control group (P=0.009). Furthermore, mifepristone, a GC receptor antagonist, blocked the inhibition of tumour growth induced by DEX. In the control group, tumour cells showed positive reactivity for nuclear glucocorticoid receptors (GR) by immunohistochemistry. The results of this study indicate that tumour growth inhibition by DEX in murine osteosarcoma may be via GR.

Steroids affect collateral sensitivity to gemcitabine of multidrug-resistant human lung cancer cells

Gemcitabine is phosphorylated by deoxycytidine kinase and thymidine kinase 2 and during S-phase incorporated into DNA. The steroids cortisol and dexamethasone, which regulate cell proliferation and gene expression, are pumped out of the cell by the membrane efflux pumps P-glycoprotein and multidrug resistance-associated protein (MRP), which are blocked by verapamil. In parental non-small cell lung cancer (NSCLC) cells (SW1573), 5 microM cortisol and 100 nM dexamethasone decreased sensitivity to gemcitabine. However, both cortisol and dexamethasone only decreased sensitivity with verapamil in MRP (2R120) and P-glycoprotein (2R160) overexpressing variants. Cortisol decreased deoxycytidine kinase activity in SW1573 cells and cortisol with verapamil in 2R120 and 2R160 cells. Dexamethasone with verapamil decreased deoxycytidine kinase activity in 2R160. Cortisol decreased thymidine kinase 2 activity in 2R120 and 2R160 cells. Dexamethasone decreased thymidine kinase 2 activity in SW1573, 2R120 and 2R160 cells. In conclusion, since dexamethasone is frequently used to treat side effects of oncolytic therapy, a decrease of sensitivity to gemcitabine by steroids might be clinically relevant.

Colorimetric detection of glutamine synthetase-catalyzed transferase activity in glucocorticoid-treated skeletal muscle cells

Induction of the enzyme glutamine synthetase (GS) by corticosteroids correlates with muscle wasting and gluconeogenesis, characteristic side effects of chronic glucocorticoid treatment. This highlights the importance of developing robust high-throughput assays to measure drug-induced GS in whole cells. We have optimized a colorimetric method to measure GS-catalyzed gamma-glutamyltransferase (GT) activity in rat L6 skeletal muscle cells (96-well-plate format) and human skeletal muscle cells (24-well-plate format). We observe a fourfold increase in GT activity in dexamethasone treated L6 cells, as compared to untreated cells, with good reproducibility in the measurements (errors of less than 5%). This assay can distinguish between partial agonists such as halopredone acetate and complete agonists such as prednisolone and measure the potency of known glucocorticoid receptor (GR) antagonists like mifepristone. Importantly, the ability of corticosteroids to induce GS-catalyzed GT activity correlates well with their whole cell GR binding potency, indicating a GR-specific effect. Interestingly, in general, induction of GT activity by commonly administered anti-inflammatory corticosteroid drugs is comparable in rat and human skeletal muscle cells, which emphasizes the potential of a rat model system to study GS induction and muscle wasting by these drugs in humans.

Vesnarinone and glucocorticoids cooperatively induce G1 arrest and have an anti-tumour effect on human non-small cell lung carcinoma cells grown in nude mice

Vesnarinone, an oral cardiotonic, inhibited the growth of several human non-small cell lung carcinoma cell lines, and its anti-proliferative effects in vitro and in vivo were greatly enhanced by combination with glucocorticoids, but not other steroids. Simultaneous treatment with vesnarinone and dexamethasone is the most effective to evoke the synergistic effect in the growth inhibition of lung carcinoma EBC-1 cells. Dexamethasone and other glucocorticoids induced morphological changes in EBC-1 cells and these agents together with vesnarinone induced alkaline phosphatase activity, which is a typical marker of type II pneumocyte maturation. This treatment arrested the growth of the cells at the G1 phase, indicating that this treatment is cytostatic rather than cytotoxic. These results suggest that vesnarinone plus glucocorticoid might be useful in lung cancer therapy.

Expression of vitamin D receptor in lung cancer

The active metabolite of vitamin D 1,25-dihydroxycholecalciferol is a hormone-like agent that regulates cell differentiation and proliferation. Various vitamin D derivatives have been shown to induce differentiation in neoplastic cells. The prerequisite for any hormone action is the presence of its receptor. We studied the expression of vitamin D receptor in human lung cancer cell lines and in primary lung cancer tissue. Employing the polymerase chain reaction, 10 out of 11 cell lines stemming from small-cell lung cancer and 15 out of 15 cell lines stemming from non-small-cell lung cancer demonstrated vitamin D receptor expression. An immunohistochemical analysis, using a specific monoclonal antibody, demonstrated vitamin D receptor protein expression in 31 out of 117 (26%) primary small-cell lung cancer cases tested. Positive cells exhibited a nuclear reaction pattern. Twenty-one out of 37 primary non-small-cell lung cancer cases, particularly adenocarcinomas (9/14) and squamous-cell carcinomas (10/15), exhibited vitamin D receptor. Results indicate that a subset of lung cancer cases may be susceptible to the differentiating effects of vitamin D analogues.