• Journal of Life Science
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• v.16 no.5
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• pp.759-766
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• 2006

Acute promyelocytic leukemia (APL) is a myeloid leukemia caused by over-expression of fusion protein, PML/RAR$({\alpha})$, which was the result of chromosomal translocation and induces the blockage of differentiation of affected promyelocytes. Pharmacological dose of retinoic acid induces the activation of and subsequent degradation of PML/RAR$({\alpha})$ fusion protein, and then APL cells undergo through the normal differentiation pathway. Arsenic trioxide has proved effective in causing remission of acute promyelocytic leukemia by inducing apoptosis of this tumor cells, whereas the heterogeneity of cellular susceptibility to this cytotoxic agent limited its usage on more types of tumors in clinic. This work showed that arsenic trioxide could induce apoptosis of a panel of acute promyelocytic leukemic cell lines, all-trans-retinoic acid (ATRA) sensitive NB4 cells and ATRA resistant UF-1 cell. They were investigated with regard to the correlation between the inherent or intrinsic cellular level of GSH and the apoptotic susceptibility of the cells to arsenic trioxide. We manifested, in two cell types, the inherently existed difference in intracellular GSH level reactive to the arsenic trioxide, and a positive correlation between the GSH level and their apoptotic sensitivity to arsenic trioxide. And it showed that arsenic trioxide could differentiate promyelocytic cancer cells to the cells possessed of dendritic cell surface markers. Unravelling the cause of the different susceptibility between leukemic cells and proving that promyelocyte could be differentiated to dendritic cells by arsenic trioxide will help not only to understand the mechanism underlying the complete remission of acute promyelocytic leukemia induced by arsenic trioxide, but also to expand its clinical usage.

• Radiation Oncology Journal
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• v.23 no.4
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• pp.211-216
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• 2005

Purpose: It has been reported that all-trans retinoic acid (ATRA) can inhibit glioma growing in vitro. However, clinical trials with ATRA alone in gliomas revealed modest results. ATRA has been shown to increase radiosensitivity in other tumor types, so combining radiation and ATRA would be one of alternatives to increase therapeutic efficacy in malignant gliomas. Thus, we intended to know the role of catalase, which is induced by ATRA, for radiosensitivity if radiation-reduced reactive oxygen species (ROS) is removed by catalase, the effect of radiation will be reduced. Materials and Methods: A rat glioma cell line (36B10) was used for this study. The change of catalase activity and radiosensitivity by ATRA, with or without 3-amino-1, 2, 4-triazole (ATZ), a chemical inhibitor of catalase were measured. Catalase activity was measured by the decomposition of $H_2O_2$ spectrophotometrically Radiosensitivity was measured with clonogenic assay. Also ROS was measured using a 2, 7-dichlorofluorescein diacetate spectrophotometrically. Results: When 36B10 cells were exposed to 10, 25 and $50{\mu}M$ of ATRA for 48 h, the expression of catalase activity were increased with increasing concentration and incubation time of ATRA. Catalase activity was decreased with increasing the concentration of AT (1, $10{\mu}M$) dose-dependently. ROS was increased with ATRA and it was augmented with the combination of ATRA and radiation. ATZ decreased ROS production and increased cell survival in combination of ATRA and radiation despite the reduction of catalase. Conclusion: The increase of ROS is one of the reasons for the increased radiosensitivity in combination with ATRA. The catalase that is induced by ATRA doesn't decrease ROS production and radiosensitivity.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.5
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• pp.1809-1817
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• 2012

Background: Gastric cancer is frequently lethal despite aggressive multimodal therapies, and new treatment approaches are therefore needed. Retinoids are potential candidate drugs: they prevent cell differentiation, proliferation and malignant transformation in gastric cancer cell lines. They interact with nuclear retinoid receptors (the retinoic acid receptors [RARs] and retinoid X receptors [RXRs]), which function as transcription factors, each with three subclasses, ${\alpha}$, ${\beta}$ and ${\gamma}$. At present, little is known about retinoid expression and influence on prognosis in gastric cancers. Patients and Methods: We retrospectively analyzed the expression of the subtypes RARa, $RAR{\beta}$, $RAR{\gamma}$, RXRa, $RXR{\beta}$, $RXR{\gamma}$ by immunohistochemistry in 147 gastric cancers and 51 normal gastric epithelium tissues for whom clinical follow-up data were available and correlated the results with clinical characteristics. In addition, we quantified the expression of retinoid receptor mRNA using real-time PCR (RT-PCR) in another 6 gastric adenocarcinoma and 3 normal gastric tissues. From 2008 to 2010, 80 patients with gastric cancers were enrolled onto therapy with all-trans-retinoic acid (ATRA). Results: RARa, $RAR{\beta}$, $RAR{\gamma}$ and $RXR{\gamma}$ positively correlated with each other (p < 0.001) and demonstrated significantly lower levels in the carcinoma tissue sections (p < 0.01), with lower $RAR{\beta}$, $RAR{\gamma}$ and RXRa expression significantly related to advanced stages (p < =0.01). Tumors with poor histopathologic grade had lower levels of RARa and $RAR{\beta}$ in different histological types of gastric carcinoma (p < 0.01). Patients whose tumors exhibited low levels of RARa expression had significantly lower overall survival compared with patients who had higher expression levels of this receptor (p < 0.001, HR=0.42, 95.0% CI 0.24-0.73), and patients undergoing ATRA treatment had significantly longer median survival times (p = 0.007, HR=0.41, 95.0% CI 0.21-0.80). Conclusions: Retinoic acid receptors are frequently expressed in epithelial gastric cancer with a decreased tendency of expression and RARa may be an indicator of a positive prognosis. This study provides a molecular basis for the therapeutic use of retinoids against gastric cancer.

• The Korean Journal of Physiology and Pharmacology
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• v.19 no.2
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• pp.105-109
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• 2015

NgR1, a Nogo receptor, is involved in inhibition of neurite outgrowth and axonal regeneration and regulation of synaptic plasticity. P19 embryonal carcinoma cells were induced to differentiate into neuron-like cells using all trans-retinoic acid and the presence and/or function of cellular molecules, such as NgR1, NMDA receptors and STAT3, were examined. Neuronally differentiated P19 cells expressed the mRNA and protein of NgR1, which could stimulate the phosphorylation of STAT3 when activated by Nogo-P4 peptide, an active segment of Nogo-66. During the whole period of differentiation, mRNAs of all of the NMDA receptor subtypes tested (NR1, NR2A-2D) were consistently expressed, which meant that neuronally differentiated P19 cells maintained some characteristics of neurons, especially central nervous system neurons. Our results suggests that neuronally differentiated P19 cells expressing NgR1 may be an efficient and convenient in vitro model for studying the molecular mechanism of cellular events that involve NgR1 and its binding partners, and for screening compounds that activate or inhibit NgR1.

• Tuberculosis and Respiratory Diseases
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• v.44 no.1
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• pp.162-174
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• 1997

Background : Metabolic cooperation via gap junctional intercellular communication (GJIC) is an important mechanism of the bystander effect in gene therapy using the Herpes Simplex Virus thymidine kinase/ganciclovir (HSVtk) "prodrug" system. Since retinoids have been reported to increase GJIC by induction of connexin 43 expression, we hyporthesized that treatment of tumor cells with retinoic acid could augment the bystander effect of the HSVtk/GCV system and result in improved tumor cell killing by enhancing GJIC. Methods : We transferred HSVtk gene to SKHep-J cell line that does not express connexin43, and also transferred the gene to human and murine mesothelioma cell lines that express connexin43. We verified that retinoic acid enhanced GJIC utilizing a functional double-dye transfer study and evaluated the effects of retinoic acid on the growth rate of tumor cells. We then tested the effects of retinoic acid on bystander-mediated cell killing. Results : Addition of all-trans retinoic acid (RA) increased GJIC in cell lines expressing connexin 43 and was asspciated with more efficient in vitro bystander killing in cells transduced with HSVtk via adenoviral and retroviral vectors. In contrast, there was no increase in the efficiency of the bystander effect after exposure to RA in a cell line which had no delectable connexin 43. Conclusion : These results provide evidence that retinoids can augment the efficiency of cell killing with the HSVtk/GCV system by enhancing bystander effect and may thus be a promising new approach to improve responses in gene therapy utilizing the HSVtk system to treat tumors.

• Toxicological Research
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• v.32 no.3
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• pp.239-243
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• 2016

Propolis is a multicomponent, active, complex resinous substance collected by honeybees from a variety of plant sources. We have studied the effect of propolis on neurite outgrowth of SH-SY5Y human neuroblastoma cells induced to differentiate by all-trans-retinoic acid (RA). Propolis, at a concentration of $3{\mu}g/mL$, had no significant effect on the viability of differentiating SH-SY5Y cells. However, the neurite outgrowth of the differentiating SH-SY5Y cells treated with propolis ($0.3{\sim}3{\mu}g/mL$) for 48 hr was significantly inhibited in a dose-dependent manner. Treatment of RA-stimulated differentiating SH-SY5Y cells with 0.3 to $3{\mu}g/mL$ propolis resulted in decreased level of transglutaminase and 43-kDa growth-associated protein (GAP-43) in a dose-dependent manner. The results indicate that propolis is able to inhibit neurite outgrowth of differentiating SH-SY5Y cells.

• Toxicological Research
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• v.26 no.1
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• pp.61-66
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• 2010

Retinoids have many beneficial effects on dermatological applications. But, retinoids cause skin irritation. In this study, the safety of retinoids was clarified via both primary skin irritation test in rabbits and sensitization study using an integrated model for the differentiation of chemical-induced allergic and irritant skin reaction (IMDS), an alternative method to sensitization test. The effects of retinoids on the change of ultraviolet A (UVA)-induced matrix metalloproteinase-1 (MMP-1) in human skin fibroblasts and the modulation of type-1 pN collagen synthesis in hairless mice were examined to clarify the anti-wrinkle effects. Alltrans retinol (t-ROL) and its derivative, all-trans retinoic acid (t-RA), showed mild skin irritation but did not induce the sensitization. t-ROL and t-RA exerted anti-wrinkle effects by inhibiting the UVA-induced MMP-1 in human skin fibroblasts and increasing the type-1 pN collagen synthesis in hairless mice. These findings suggest that retinoids do not induce the allergy, and show anti-wrinkle effects by decreasing MMP-1 activation and increasing collagen synthesis.

• Biomedical Science Letters
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• v.16 no.1
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• pp.1-9
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• 2010

In order to understand the effects of all-trans-RA on palate development, RA was injected into the abdominal cavity of pregnant mice and then the embryos were taken in the following days and analyzed morphologically as well as molecular biologically. When RA was administered at the stage of E11 or E15, the overall craniofacial development was retarded. The length from jaw to eye was shortened, compared to that of normal group. When the E11 embryos were exposed to RA, cleft lip was also found along with the cleft palate. In vitro palate culture experiment also revealed that RA caused cleft palate. When RT-PCR was performed, early stage administration of RA at E11 inhibited the upregulation of Hoxa7 expression at E15 through E17. Whereas in control group, high level of Hoxa7 expression was detected in the palate of E15 to E17. In the case of Bax, the expression was decreased from E16, while remaining constant in control group. When TUNEL analysis was performed following the RA treatment at E15, TUNEL positive cells were detected in the mesenchymal cells as well as epithelial cells of palatal shelves of E16 and in E17 embryos. Whereas in normal control, TUNEL positive cells were observed mostly at the epithelium around the nasal cavity and oral cavity where rugae is made. These results altogether indicate that exposure to RA during palate development causes facial deformity including cleft palate and cleft lip by modulating the expression of homeotic genes such as Hoxa7 as well as an apoptosis-related gene, Bax, and thus malregulating the apoptosis.

• BMB Reports
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• v.39 no.6
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• pp.722-729
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• 2006

Recently, we have reported that 3-hydrogenkwadaphnin (3-HK), a diterpene ester isolated from Dendrostellera lessertii (Thymealeaceae), is very effective against leukemia cell lines without any detectable effects on normal cells (Moosavi et al., 2005b). In this study, we report that 3-HK induces $G_1$ cell-cycle arrest, differentiation and apoptosis in APL NB4 cell line. Indeed, the drug between 24 to 96 h induced 7-65% growth inhibition of NB4 cells. Cell viability was also decreased by 2-55% between 24 to 96 h treatments with the drug, respectively. These effects of the drug were also dose-dependent. According to flow cytomtry results, 3-HK (15 nM) induced a significant G1-arrest up to 24 h which was consequently followed with appearance of sub-$G_1$ peak at 72 to 96 h. Hoechst 33258 staining and DNA fragmentation assays confirmed the occurrence of apoptosis among the treated cells. On the other hand, NBT reducing assay, Wright-Giemsa staining, phagocytic activity and expression of cell surface markers (CD11b and CD14) confirmed that the inhibition of proliferation is associated with differentiation especially toward macrophage-like morphology. Interestingly, 3-HK at 5 and 10 nM enhanced the effects of all-trans retinoic acid (ATRA) in NB4 cells. Based on these results, 3-HK might become an ideal candidate for treatment of APL patients pending full exploration of its biological functions.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.867-870
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• 2001

All-trans-retinoic acid (RA) plays essential roles in the regulation of differentiation and proliferation. It has been proved that RA is effective in the treatments of epithelial and hematologic malignancies. However, in spite of its pronounced effects, the clinical applications of RA are limited due to the retinoid acute resistance. Although RA induces complete remission in a high proportion of the patients of acute promyelocytic leukemia (APL), the cancer was relapsed in many patients after a brief remission in spite of a continued RA treatment. Patients who relapsed from remission that was initially induced by RA had clinically resistant to further RA treatment. That is, specific cytochrome P450 enzymes in the liver were induced by the continuous oral administration of RA, thereby accelerating the metabolism of RA. To overcome this problem, biodegradable microspheres were proposed by us, previously. And, several microsphere formulations for RA delivery have been prepared and studied on their effectiveness. Recently, poly(D,L-lactide) (PDLLA) microsphere formulation was optimized, And, from the animal studies by using a mouse and a rat, it have appeared to be effective on both the inhibition of tumor growth and chemoprevention of a carcinogenesis. In this study, subacute toxicities of the PDLLA microsphere formulation have been investigated as a preclinical test. For the test, the microspheres was injected subcutaneously into the back site of rats, and body weight change, clinical signs, hematological changes, blood biochemistry were evaluated. As a result, severe toxicities such as mortality were observed at the dose of 100mg RA/kg, and toxicities were not observed at the dose of 50mg RA/kg, which is the effective dose against carcinogenesis. Bone fracture, observed at several rats, might be inhibited by treating them with anti-inflammatory drugs.