Effect Of 9-cis Retinoic Acid Research Articles

13-cis Retinoic Acid-Mediated Modulation of Human Meibomian Gland Epithelial Cells Development: Implications for In Vitro Modeling of Meibomian Gland Dysfunction.

Purpose: This study aimed to investigate the effect of 13-cis retinoic acid (13-cis RA) on human meibomian gland epithelial cells (HMGECs) and explore the potential of using this experimental model as an in vitro approach for studying meibomian gland dysfunction (MGD). Methods: First, HMGECs were cultured with 13-cis RA at different doses and times, and cell viability and proliferation rates were assessed to determine the appropriate stimulation concentration and time. Subsequently, during the proliferation stage, the expression of proliferation, inflammation, and oxidative stress genes and their products were evaluated. The meibum synthesis capacity was determined during the differentiation stage. Additionally, the peroxisome proliferator-activated receptor gamma (PPARγ) antagonist GW9662 was used as a control to assess the impact of 13-cis RA on PPARγ. Results: 13-cis RA significantly inhibited cell viability and proliferation in a time-dose response manner. Under the stimulation of 2 and 5 μM for 48 h during the proliferation stage, a significant decrease was observed in the expression of cell proliferation markers Ki67, antioxidant SOD-2, and Nrf-2. However, the expression of the pro-inflammatory factors IL-1β, IL-8, MMP9, and oxidative stress markers NOX-4 and reactive oxygen species increased. During the differentiation stage, it suppressed meibum synthesis and the expression of meibocyte differentiation-related proteins adipose differentiation-associated protein 4 (ADFP4), elongation of very long chain fatty acid protein 4 (ELOVL4), sterol regulatory element-binding protein 2 (SREBP-2), and PPARγ. Conclusion: 13-cis RA inhibited cell viability, promoted inflammation and oxidative stress, and suppressed meibum synthesis through the PPARγ pathway. Our study shed light on the effect of 13-cis RA on HMGECs and provided a promising direction for studying MGD in vitro.

Dual effects of 9-cis retinoic acid on ACTH-dependent hyperplastic adrenal tissues

Retinoids play a pivotal role in adrenal development and differentiation. Recent clinical trials revealed therapeutic potential of both all-trans and 9-cis retinoic acid in patients with cortisol excess due to a pituitary ACTH-secreting adenoma and indicated that retinoids might act also on the adrenal. Aim of the present study was to evaluate the effect of 9-cis retinoic acid on adrenals from patients with ACTH-dependent Cushing’s syndrome. Adrenal specimens from six patients with Cushing’s disease were incubated with 10 nM–1 µM 9-cis retinoic acid with and without 10 nM ACTH. Cortisol secretion was measured by immunoassay and expression of genes involved in steroidogenesis as well as retinoic acid action were evaluated by real-time RT-PCR. Incubation with 10–100 nM 9-cis retinoic acid increased spontaneous cortisol secretion and expression of STAR and CYP17A. On the other hand, in wells treated with ACTH, 9-cis retinoic acid markedly diminished ACTH receptor upregulation and no stimulatory effect on cortisol secretion or steroidogenic enzyme synthesis was observed. ACTH itself increased ligand-induced retinoic acid receptor expression, possibly enhancing sensitivity to retinoic acid. Our findings indicate that the effect of 9-cis retinoic acid in presence of ACTH is distinct from unchallenged wells and support the hypothesis of a direct adrenal action in patients with Cushing’s disease.

Role of Chicoric Acid and 13-Cis Retinoic Acid in Mycobacterium tuberculosis Infection Control by Human U937 Macrophage.

Mycobacterium tuberculosis (Mtb) survives and proliferates within the main cells of the innate immune system, macrophages. The goal of our study was to investigate the immunostimulatory effects of 13-cis retinoic acid (RA) and chicoric acid (CA) in human U937 macrophages against H37Ra Mtb infection by evaluating its potential role in the cell surface expression of HLA-DR, CD14 molecules as well as nitric oxide (NO) production and prevention of the Mtb growth within macrophages. In this study, we investigated the effects of 13-cis RA and CA on Mtb-infected macrophages using flowcytometry and Griess methods, respectively. Moreover, inhibitory effect of 13-cis RA and CA on Mtb growth within macrophages were assessed using colony-forming unit. 13-Cis RA and CA enhanced the cell surface expression of HLA-DR and CD14 molecules on U937 macrophages and prevented the growth of Mtb within macrophages. In addition, 13-cis RA and CA, have increased NO generation compared to untreated control macrophages, significantly (p < 0.001). Both drugs have a significant inhibitory effect on Mtb growth but CA at the highest concentration was more potent than 13-cis RA (p < 0.05). The results of our study showed that infected U937 macrophages treated with 13-cis RA and CA represented significant increases in NO production, CD14 and HLA-DR expression and also prevents intracellular survival of Mtb. Therefore, 13-cis RA and CA may have a significant therapeutic approach in the control of Mtb infection.

Prevention of Postsurgical Lymphedema by 9-cis Retinoic Acid

To determine the effect of 9-cis retinoic acid (9-cis RA) on postsurgical lymphedema. 9-cis RA promotes lymphangiogenesis in vitro and in vivo and has promise as a therapeutic agent to limit the development of postsurgical lymphedema. Lymphedema was induced in the right hind limb after a single fraction of 20 Gy radiation, popliteal lymphadenectomy, and lymphatic vessel ablation. Postoperatively, mice were randomly divided in to 2 groups that received daily intraperitoneal injections of either (1) an oil-based vehicle solution (control) or (2) 0.08 mg/kg of 9-cis RA dissolved in a vehicle solution. Outcome measures included paw thickness, lymphatic drainage, and lymphatic vessel density as measured by podoplanin immunohistochemistry and whole mount skin analysis. Using our combined injury protocol, postsurgical lymphedema was observed 89% of the time. 9-cis RA-treated animals had less early postsurgical edema and significantly less paw lymphedema compared with vehicle-treated animals at all time-points (P < 0.001). 9-cis RA-treated animals had significantly faster lymphatic drainage as measured by indocyanine green clearance and increased lymphatic vessel density as measured by podoplanin immunohistochemistry (P < 0.001) and whole mount skin analysis (P < 0.05). We have developed a highly reproducible model of secondary lymphedema and have demonstrated that 9-cis RA significantly prevents postsurgical lymphedema. Treatment with 9-cis RA is associated with increased lymphatic clearance and lymphangiogenesis. Because 9-cis RA (alitretinoin) is already approved for clinical use by the US Food and Drug Administration for other conditions, it has the potential to be repurposed as a preventative agent for postsurgical lymphedema in humans.

Synergistic anti-tumour effects of 13-cis retinoic acid and lovastatin in pancreatic neuroendocrine tumour (BON1) cells through enhanced EGFR inhibition

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Study on 13-cis retinoic acid inducing differentiation of three types of human neuroblastoma cell lines in vitro

Objective To investigate the effects of 13-cis retinoic acid (13-cis RA) in inducing differen-tiation of 3 types of human neuroblastoma (NB) cells in vitro. Methods The status of MYCN gene amplification of cultured SH-SY5Y, SK-N-SH and SK-N-BE2 cells was detected by fluorescence in situ hybridization.After treatment with different concentrations of 13-cis RA, morphological changes were observed by phase-contrast microscope, and neuron-specific enolase (NSE) concentrations were determined by enzyme linked immunosorbent assay.The cell viability was measured through cell counting kit-8 assay, and the cell apoptosis was assayed with flow cytometry (FCM). Results The morphological changes in differentiation were observed in all 3 types of NB cells after 13-cis RA treatment.MYCN amplification was detected in SK-N-BE2 cells even after 13-cis RA treatment, while the other 2 cell lines were amplification-null.After different concentrations of 13-cis RA treatment, NSE concentration increased with prolonged time, especially for SK-N-BE2 cell(F=27.00, P<0.000 1).13-cis RA stimulated cell proliferation within 48 hours of treatment, and then inhibited cell growth.FCM indicated that the degree of apoptosis in SH-SY5Y cell was significantly higher after 13-cis RA treatment of 10 μmol/L concentration for continuous 96 h and 120 h as compared to the control group (F=16.21, P=0.011; F=16.04, P=0.016). Cell apoptosis of SK-N-SH cell after 13-cis RA treatment of 1 μmol/L and 10 μmol/L concentration for 48 h, were significantly higher than those of the control group(F=15.05, P=0.012; F=31.18, P=0.005); while SK-N-BE2 cell with different concentrations of 13-cis RA(1 μmol/L, 5 μmol/L, 10 μmol/L) for 120 h were significantly higher than those of the control group(F=9.05, P=0.030; F=11.38, P=0.028; F=7.88, P=0.041). Conclusions The present study showed that 13-cis RA could induce differentiation of human NB cells in vitro.It induces cell proliferation within 48 hours of 13-cis RA, and thereafter suppresses cell growth.No improvement was found in MYCN amplification cells with the detection of DNA level after 13-cis RA treatment, which suggests that combined treatment is possibly needed. Key words: Neuroblastoma; Differentiation; 13-cis retinoic acid; MYCN gene

Retinoic acid as a survival factor in neuronal development of the grasshopper, Locusta migratoria.

Based on experience with cell cultures of adult insect neurons, we develop a serum-free culture system for embryonic locust neurons. Influences of trophic substances on survival and neurite outgrowth of developing neurons are investigated. For the first time, a positive trophic effect of 9-cis retinoic acid (9-cis RA) was shown in vitro on embryonic neurons of an insect. We observed longer cell survival of 50 % developmental stage neurons in cultures supplemented with 0.3 nM 9-cis RA. Furthermore, an influence on neuron morphology was revealed, as the addition of 9-cis RA to cell culture medium led to an increase in the number of neurites per cell. Although an RA receptor gene, LmRXR (Locusta migratoria retinoid X receptor), was expressed in the central nervous system throughout development, the influence of 9-cis RA on neuronal survival and outgrowth was restricted to 50 % stage embryonic cells.

Effect of 9-cis retinoic acid and all-trans retinoic acid in combination with verapamil on P-glycoprotein expression in L1210 cells.

The development of the most common multidrug resistance (MDR) phenotype is associated with a massive overexpression of P-glycoprotein (P-gp) in neoplastic cells. In the current study, we used three L1210 cell variants: S cells - parental drug-sensitive cells; R cells - drug-resistant cells with P-gp overexpression due to selection with vincristine; T cells - drug-resistant cells with P-gp overexpression due to stable transfection with the pHaMDRwt plasmid, which encodes human full-length P-gp. Several authors have described the induction of P-gp expression/activity in malignant cell lines after treatment with all-trans retinoic acid (AtRA; ligand of retinoic acid nuclear receptors, RARs). An isomer of AtRA also exists, 9-cis retinoic acid, which is a ligand of both RARs and nuclear retinoid X receptors (RXRs). In a previous work, we described that the combined treatment of R cells with verapamil and AtRA induces the downregulation of P-gp expression/activity. In the current study, we studied the expression of RARs and RXRs in S, R and T cells and the effects of treatment with AtRA, 9cRA and verapamil on P-gp expression, cellular localization and efflux activity in R and T cells. We found that the overexpression of P-gp in L1210 cells is associated with several changes in the specific transcription of both subgroups of nuclear receptors, RARs and RXRs. We also demonstrated that treatment with AtRA, 9cRA and verapamil induces alterations in P-gp expression in R and T cells. Particularly, combined treatment of R cells with verapamil and AtRA induced downregulation of P-gp content/activity. In contrast, similar treatment of T cells induced slight increase of P-gp content without any changes in efflux activity of this protein. These findings indicate that active crosstalk between the RAR and RXR regulatory pathways and P-gp-mediated MDR could take place.

The 9-Cis Retinoic Acid Signaling Pathway and Its Regulation of Prostaglandin-Endoperoxide Synthase 2 During In Vitro Maturation of Pig Cumulus Cell-Oocyte Complexes and Effects on Parthenogenetic Embryo Production1

The addition of 9-cis retinoic acid to the oocyte maturation culture medium has a beneficial effect on in vitro fertilized embryos. However, the mechanism of this activity is not known. Therefore, this study was done to elucidate the effect of 9-cis retinoic acid on parthenogenetic embryo production and its signaling pathway and molecular function during in vitro maturation of porcine cumulus cell-oocyte complexes (COCs). Concentrations of 0, 5, 50, and 500 nM 9-cis retinoic acid were added to the in vitro maturation medium, and the embryos were assessed after parthenogenetic activation. Cumulus cells and oocytes from the in vitro matured COCs were separated and subjected to RT-PCR and real-time RT-PCR for detecting retinoic acid receptors and measuring expression of prostaglandin-endoperoxide synthase1 and 2. The addition of 5 nM 9-cis retinoic acid to the maturation medium was beneficial for parthenogenetic embryo production. The effect of 9-cis retinoic acid was exerted directly through the oocytes via the retinoic acid receptor alpha and retinoid X receptor gamma signaling pathways and indirectly through the cumulus cells by the retinoic acid receptor beta and gamma and retinoid X receptor alpha and beta signaling pathways. The addition of 5 nM 9-cis retinoic acid-stimulated cumulus cells reaches full expansion by suppressing their excessive expression of prostaglandin-endoperoxide synthase 2. This study shows that 9-cis retinoic acid can exert its beneficial effect on parthenogenetic embryo production in pigs by multidimensional pathways affecting oocyte maturation.

254 9-cis RETINOIC ACID INHIBITS CUMULUS CELL APOPTOSIS DURING IN VITRO MATURATION OF BOVINE OOCYTES THROUGH INHIBITION OF AP-1 PATHWAY

Cumulus cells (CC) play a critical role in oocyte maturation and fertilization via gap junctions. The oocyte itself maintains CC health to favour oocyte maturation via the secretion of paracrine growth factors. However, the antiapoptotic effects of oocyte-secreted factors follow a gradient from the site of the oocytes. Moreover, degrees of CC apoptosis are inversely related to the in vitro embryo development. Therefore, inhibition of CC apoptosis is important for efficient in vitro embryo development. The beneficial effects of retinoic acid (RA) during in vitro embryo production are well known in different species. However, the effect of RA on CC apoptosis is yet to be elucidated. All-trans RA and 9-cis RA are the natural components of retinoids, and all-trans RA are metabolized to 9-cis RA for physiological function. Therefore, the objective of the present study was to evaluate the effect of 9-cis RA on the mechanism for inhibition of apoptosis in CC. Slaughterhouse cumulus–oocyte complexes (COC) were matured in vitro in TCM-199-based in vitro maturation medium containing 0 or 5 mM 9-cis RA for 23 to 24 h (15 COC/100 μL droplet) at 38.5°C and 5% CO2 in air with maximum humidity. Following in vitro maturation, COC of a droplet were fixed in 4% paraformaldehyde for TUNEL staining using In Situ Cell Death Detection Kit (Roche, Budapest, Hungary). The proportion of apoptotic cells was estimated using Olympus Soft Imaging Solutions GmBH (Olympus, Münster, Germany). The COC of the remaining droplet were denuded. The CC were frozen and stored at –80°C. The CC of 3 different cultures were pooled, and total RNA was extracted using RNeasy Mini Kit (Qiagen, Valencia, CA, USA). Total RNA was reverse transcribed into cDNA using Omniscript Reverse Transcription kit (Qiagen). Relative expression of candidate genes was quantified using SYBER green real-time PCR with ΔΔ CT method. The expression was normalized against β-actin, glyceraldehyde 3-phosphate dehydrogenase, and 18s rRNA genes expression. The PCR efficiencies were calculated using relative calibration curves following 10-fold dilution series at 5 measuring points. Data were analysed for one-way ANOVA. The proportion of apoptotic cells was low in the 9-cis RA group (1.3 v. 3.3% of total CC; P &lt; 0.05). Expression of tumor necrosis factor-α (11.1 v. 1.0; P &lt; 0.001), caspase9 (2.0 v. 1.0; P &lt; 0.01), and caspase3 (2.1 v. 1.0; P &lt; 0.001) genes was down-regulated in the 9-cis RA group, whereas expression of Bcl2 gene was increased (1.0 v. 2.6 fold; P &lt; 0.05). Moreover, the expression of c-fos gene of AP-1 pathway was down-regulated (1.9 v. 1 fold; P &lt; 0.05) in the 9-cis RA group. Retinoic acid suppressed the expression of NF-kB, which in turn inhibits tumor necrosis factor-α-mediated caspase activity. However, the expression of NF-kB in CC was not affected by 9-cis RA (1.1 v. 1.0; P &gt; 0.05). In conclusion, the present study indicated that 9-cis RA may inhibit cumulus cell apoptosis through suppression of AP-1 pathway. This work was partly supported by a scholarship from the BK21 program, the KRF (KRF-2008-211-F00011), the IPET (108068-03-1-SB010), and the KOSEF (10525010001-05N2501-00110).

A Randomized Phase II Chemoprevention Trial of 13-CIS Retinoic Acid with Or without α Tocopherol or Observation in Subjects at High Risk for Lung Cancer

No chemoprevention strategies have been proven effective for lung cancer. We evaluated the effect of 13-cis retinoic acid (13-cis RA), with or without alpha tocopherol, as a lung cancer chemoprevention agent in a phase II randomized controlled clinical trial of adult subjects at high risk for lung cancer as defined by the presence of sputum atypia, history of smoking, and airflow obstruction, or a prior surgically cured nonsmall cell lung cancer (disease free, >3 years). Subjects were randomly assigned to receive either 13-cis RA, 13-cis RA plus alpha tocopherol (13-cis RA/alpha toco) or observation for 12 months. Outcome measures are derived from histologic evaluation of bronchial biopsy specimens obtained by bronchoscopy at baseline and follow-up. The primary outcome measure is treatment "failure" defined as histologic progression (any increase in the maximum histologic score) or failure to return for follow-up bronchoscopy. Seventy-five subjects were randomized (27/22/26 to observations/13-cis RA/13-cis RA/alpha toco); 59 completed the trial; 55 had both baseline and follow-up bronchoscopy. The risk of treatment failure was 55.6% (15 of 27) and 50% (24 of 48) in the observation and combined (13 cis RA plus 13 cis RA/alpha toco) treatment arms, respectively (odds ratio adjusted for baseline histology, 0.97; 95% confidence interval, 0.36-2.66; P = 0.95). Among subjects with complete histology data, maximum histology score in the observation arm increased by 0.37 units and by 0.03 units in the treated arms (difference adjusted for baseline, -0.18; 95% confidence interval, -1.16 to 0.81; P = 0.72). Similar (nonsignificant) results were observed for treatment effects on endobronchial proliferation as assessed by Ki-67 immunolabeling. Twelve-month treatment with 13-cis RA produced nonsignificant changes in bronchial histology, consistent with results in other trials. Agents advancing to phase III randomized trials should produce greater histologic changes. The addition of alpha tocopherol did not affect toxicity.

Effect of 9-cis Retinoic Acid on Dopamine D2 Receptor Expression in Pituitary Adenoma Cells

The dopamine receptor subtype 2 (D2R) promoter contains a functional retinoic acid response element involved in the control of D2R expression. The aim of the study was to evaluate the effect of 9-cis retinoic acid (9-cis RA) on D2R protein expression in human pituitary adenomas and GH3 cell line. Treatment with 9-cis RA (100 nM for 48 hrs) caused a 109 +/- 32% increase of basal D2R levels in five of eight growth hormone (GH)-secreting adenomas (GH-omas), a 129 +/- 28% increase in 7 of 11 nonfunctioning adenomas, and no effect in two resistant prolactinomas by Western blotting. The lack of D2R induction in some tumors was not associated with a different pattern of retinoid x receptor (RXR) and retinoic acid receptor (RAR) isoform expression that was similar in all tumors by immunohistochemistry. While the induction of D2R did not affect the slight but significant inhibitory effect exerted by dopamine (10 nM) on in vitro GH release by GH-oma cultured cells, in pituitary GH3 cell lines cis-9 RA enhanced the dopamine-induced inhibition of in vitro GH release (% inhibition: 16 +/- 2 versus 26 +/- 5, P < 0.05), cell proliferation (25 +/- 2% versus 44 +/- 5%, P < 0.05) and cell viability (16 +/- 0.8% versus 29 +/- 1%, P < 0.05), likely by activating caspase-3 (28 +/- 3% versus basal, P < 0.05). In conclusion, this study provides novel evidence for a permissive role of retinoids on the expression of D2R in a good proportion of pituitary tumors and on the generation of pro-apoptotic signals in GH3 cell line.

13-cis Retinoic Acid Induces Apoptosis and Cell Cycle Arrest in Human SEB-1 Sebocytes

Isotretinoin (13-cis retinoic acid (13-cis RA)) is the most potent inhibitor of sebum production, a key component in the pathophysiology of acne, yet its mechanism of action remains largely unknown. The effects of 13-cis RA, 9-cis retinoic acid (9-cis RA), and all-trans retinoic acid (ATRA) on cell proliferation, apoptosis, and cell cycle proteins were examined in SEB-1 sebocytes and keratinocytes. 13-cis RA causes significant dose-dependent and time-dependent decreases in viable SEB-1 sebocytes. A portion of this decrease can be attributed to cell cycle arrest as evidenced by decreased DNA synthesis, increased p21 protein expression, and decreased cyclin D1. Although not previously demonstrated in sebocytes, we report that 13-cis RA induces apoptosis in SEB-1 sebocytes as shown by increased Annexin V-FITC staining, increased TUNEL staining, and increased cleaved caspase 3 protein. Furthermore, the ability of 13-cis RA to induce apoptosis cannot be recapitulated by 9-cis RA or ATRA, and it is not inhibited by the presence of a retinoid acid receptor (RAR) pan-antagonist AGN 193109. Taken together these data indicate that 13-cis RA causes cell cycle arrest and induces apoptosis in SEB-1 sebocytes by a RAR-independent mechanism, which contributes to its sebosuppressive effect and the resolution of acne.

9-cis retinoic acid induces insulin-like growth factor binding protein-3 through DR-8 Retinoic acid responsive elements

Retinoic acids, which have shown potential chemopreventive and therapeutic activities for several neoplastic diseases in vitro, modulate the growth-promoting and anti-apoptotic activities of insulin-like growth factors (IGFs), in part by influencing the expression of insulin-like growth factor binding protein-3 (IGFBP-3). This study sought to investigate the effect of 9-cis retinoic acid (9cRA) on the expression of IGFBP-3 and the underlying mechanisms involving retinoic acid receptor-β (RAR-ββ).The pharmacologic activity of 9cRA was characterized by monitoring target modulation as well as by evaluating the underlying mechanisms in NSCLC cells. Treatment of 9cRA inhibited proliferation of a part of NSCLC cell lines including H460 cells in clinically-achievable concentrations and induce IGFBP-3 expression in dose- and time-dependent manners. Transient transfection with a reporter construct driven by the human IGFBP-3 gene promoter indicated that 9cRA induces gene expression via the -534 to -445 region (relative to translation start site) of the IGFBP-3 promoter. Unilateral deletion and site-directed mutagenesis identified a retinoic acid responsive element (RARE), a direct repeat of two GGGTCA-related hexanucleotides separated by just 8 bp (DR-8-type response element). A co-transfection assay with a RAR-β expression vector potentiated (and with siRNA for RAR-β, diminished) the effect of 9cRA on IGFBP-3 expression. IGFBP-3 gene expression by 9cRA is mediated by a distinct DR-8 RARE located in the proximal region of the IGFBP promoter and involves the RAR-β, a putative tumor suppressor in NSCLC.

Synergistic anti-tumor effect of 13-cRA and IFN-alpha/beta in mouse renal cell carcinoma.

The synergistic anti-tumor effect of 13-cis retinoic acid (13-cRA) and interferon-alpha/beta (IFN-alpha/beta) was investigated using a highly metastatic mouse renal cell carcinoma cell subline (RenCa/F). Although 13-cRA inhibited tumor growth in vivo as well as in vitro, IFN-alpha/beta did not. Combined administration of 13-cRA and IFN-alpha/beta significantly enhanced the anti-tumor effect of 13-cRA. The retinoic acid receptor (RAR)-alpha and RAR-gamma were expressed in RenCa/F cells. Treatment with IFN-alpha/beta did not influence the expression level of these receptors at the mRNA level, which suggests that the synergism of 13-cRA and IFN-alpha/beta is not mediated through the RAR.

The effects of 13-cis retinoic acid on squamous cell carcinoma proliferation and adhesion to extracellular matrix proteins.

To understand the role of retinoids in chemoprevention, the authors examined the effects of 13-cis retinoic acid (cRA) on squamous cell carcinoma proliferation and adhesion to extracellular matrix proteins. The antiproliferative effects of cRA were first seen on day 11 (66% inhibition) and progressed through day 19 (96% inhibition). Using an adhesion assay, the authors then investigated the effects of cRA and transforming growth factor-beta1 (TGF-beta1) on cellular adhesion to purified type IV collagen, fibronectin, and laminin matrices. Cells treated for 4 days with TGF-beta1 increased adhesion by 15% to 29%, and cells treated with cRA increased adhesion by 19% to 39%. However, the use of cRA alone resulted in a decrease in adhesion when tumor cells were treated for 7 days (20% to 32%) and 15 days (25% to 40%). The authors also discuss how cRA acts as a differentiating agent on squamous cell carcinoma.

Differential modulation of thyroid hormone responsiveness by retinoids in a human cell line.

Previous studies have suggested that there is an interrelationship between responses mediated by retinoic acid (RA) and those to thyroid hormone (T3). These experiments have used transfected gene constructs, often in receptor-negative cells. To study the relationship between RA- and T3-mediated responses in intact human cells, we incubated HepG2 cells for 4 days in serum-free medium with T3 and/or RA or 9-cis-RA. Measured responses were stimulation of secreted sex hormone-binding globulin (SHBG) or inhibition of secreted T4-binding globulin (TBG). T3 induced a dose-responsive increase in SHBG secretion that was maximal at 10nM (206 +/- 24% of untreated value) and half-maximal at 0.36 +/- 0.16 nM T3. RA and 9-cis-RA, up to 100 nM, induced a slight fall in SHBG secretion to 79 +/- 9% and 88 +/- 9%, respectively. T3 induction of SHBG secretion was significantly attenuated in cells coincubated with T3(0-10nM) and RA. With T3 (10 nM) together with RA (3, 10, or 100 nM), the maximal SHBG responses were reduced to 193 +/- 24%, 151 +/- 5% and 132 +/- 30%, respectively. With T3 and 9-cis-RA (100 nM), maximal stimulation was 169 +/- 20%. Importantly, the effective half-maximal stimulatory concentration of T3 in the presence of either retinoid (3-100 nM) was unchanged at 0.3 nM T3. In addition, the inhibitory effect of 9-cis RA could not be overcome even with 300 nM T3. The threshold for the RA effect was between 0.3-1 nM, with half-maximal inhibition at 30 nM. 9-cis-RA was approximately 10-fold less potent than RA. Preliminary studies suggested that changes in SHBG messenger RNA levels were similar to those in secreted SHBG. No effect was observed with vitamin D or clofibrate, either alone or combined with T3. Conversely, T3 reduced TBG secretion, with maximal suppression to 74 +/- 5% of the control value at a T3 concentration of 10 nM. RA alone reduced TBG secretion to 76% of the control value. RA did not attenuate the effect of T3, and the two agents combined showed no synergism. Neither T3 nor RA, alone or in combination, influenced secreted total protein or albumin. RA did not alter the concentration of nuclear T3-binding sites. These data suggest that retinoids act via a gene-dependent mechanism to modulate maximal, but not half-maximal, responses to T3 in HepG2 cells with the specificity of RA greater than that of 9-cis-RA.

A single dose pharmacokinetic study of 13-cis retinoic acid (Isotretinoin, Ro 04-3780) in the pregnant New Zealand rabbit using intravenous infusion

The pharmacokinetics of 13-cis retinoic acid in the pregnant New Zealand rabbit were determined after intravenous administration. This drug displayed linear pharmacokinetics in this species. Noncompartmental pharmacokinetic analyses were performed on individual data sets and an average value determined for each parameter (n = 3/dose group). The mean Vdss, CL and t12 for the 0.5 mg/kg dose group were 534.0 ± 144.8 ml/kg, 139.2 ± 41.0 ml/h/kg and 3.8 ± 0.8 h, whereas for the 5.0 mg/kg dose group these parameters were 676.3 ± 145.5 ml/kg, 169.8 ± 18.9 ml/h/kg and 4.2 ± 1.3 h, respectively. The mean data from the 5.0 mg/kg dose group was modeled to a three-compartment model with elimination occurring from the first compartment only. The pharmacokinetic parameters of AUC, CL, Vdss, MRT and the effective half-life calculated from compartmental analysis were similar to those obtained from noncompartmental analysis. The noncompartmental pharmacokinetic parameters determined for the rabbit were found to compare favorably with those reported for the monkey. The monkey is considered to be an appropriate specie for modelling the pharmacokinetics of 13-cis retinoic acid in humans. We propose that since the pharmacokinetics of 13-cis retinoic acid are similar between the two species and the rabbit displays great sensitivity to the teratogenic effects of 13-cis retinoic acid that it may be a good animal model to use to assess the risk/benefit of 13-cis retinoic acid therapy in humans.

13-cis retinoic acid inhibits growth of adult T cell leukemia cells and causes apoptosis; possible new indication for retinoid therapy.

We evaluated the effects of 13-cis retinoic acid (13-cis RA) on the growth of peripheral blood mononuclear cells (PBMC) obtained from 12 patients with adult T cell leukemia (ATL). In general, 13-cis RA potently inhibited the growth of PBMC from ATL patients. However, the sensitivity of the cells to 13-cis RA-induced growth inhibition varied among the patients. The ATL patients fell into three groups (hypersensitive, sensitive and resistant to 13-cis RA) according to the percent reduction of 3H-thymidine incorporation before and after treatment with 13-cis RA. Agarose gel electrophoresis of total genomic DNA from a patient sensitive to 13-cis RA provided evidence of the DNA fragmentation indicative of apoptosis. The ability of 13-cis RA to induce apoptosis in PBMC from ATL patients suggests that retinoids may be useful in the treatment of ATL.

The effect of 13-cis retinoic acid (13-CIS RA) in normal cycling women: An explanation for the diverse endocrine mediated effects of 13-CIS RA

The effect of 13-cis retinoic acid (13-CIS RA) in normal cycling women: An explanation for the diverse endocrine mediated effects of 13-CIS RA