[Effect of retinociacdi combined extracts from testudinis carapacis et plastri on proliferating in MSCs and its mechanism].

OBJECTIVE: To explore the effect of retinociacdi (RA) combined extracts from Testudinis Carapacis et Plastri(PTE) on proliferating in MSCs and its mechanism. METHODS: Transfected PGL3-ID1 using the calcium phosphate co-precipitation method in rat MSCs. PTE combined with RA and retinociacdi receptor inhibitor(Ro41) acted on transfected MSCs with respective concentrations of 10(-6), 10(-7) and 10(-8) mol/L. Luciferase activity measurement was used to detect the activity of RAR and IDI 36 h later. PTE acted on MSCs 36 h,3 d and 7 d for respective concentrations of 1, 3, 30 and 100 microg/mL,then collected cells to detect RAR with RT-PCR. PTE combined with RA for 10(-7) mol/L and Ro41 for 10(-6) mol/L respectively on MSCs for 36 h,and then collected cells to detect RAR and ID1 with RT-PCR. RESULTS: PTE promoted expression of ID1 on MSCs. When combined with RA, the promotion effect became greater and it promoted expression of RAR at the same time; When inhibited RA using Ro41, the promotion of IDI was weaken by PTE. CONCLUSION: RA promotes expression of IDI on MSCs, PTE regulates proliferation and differentiation of MSCs by expression of nuclear receptor RAR.

[Effects of deer tendons collagen on osteoporosis rats induced by retinoic acid].

OBJECTIVE: To study the effects of deer tendons collagen on osteoporosis rats induced by retinoic acid. METHODS: Male Wistar rats were randomly divided into normal control group, model control group, deer tendons collagen high, medium and low-dose groups, osteoporosis rats of retinoic acid-induced were set up. Changes of body weight, bone weight, bone mineral density, bone histomorphometry, plasma phosphorus, calcium, alkaline phosphatase (ALP), bone mechanics were measured before and after treatment of deer tendons collagen. RESULTS: Compared with model control group,after treated by deer tendons collagen, body weight, bone mineral density, bone weight was increased in varying degrees, bone histomorphometry parameters were significantly different, the ALP in plasma was significantly reduced, contents of Ca, P were increased, all indicators of bone mechanics were significantly higher. CONCLUSION: Deer tendons collagen can prevent and treat retinoic acid-induced osteoporosis of rats.

The role of the reticulo-epithelial (RE) cell network in the immuno-neuroendocrine regulation of intrathymic lymphopoiesis.

The thyrnus provides an optimal cellular and humoral microenvironment for the development of immunocompetent T lymphocytes. Although yolk sac derived pre-T, committed hematopoietic stem cells enter the thymus using a homing receptor, the immigration process also requires secretion of a peptide, called thymotaxin by the cells of the reticulo-epithelial (RE) network of the thymic cellular microenvironment. The thymic RE cells are functionally specialized based on their location within the thymic microenvironment. Thus, although subcapsular, cortical, and medullary RE cells are derived from a common, endodermal in origin epithelial precursor cell, their unique location within the gland causes their specialization in terms of their immunophenotypical and in situ physiological properties. The subcapsular, endocrine, RE cell layer (giant or nurse cells) is comprised of cells filled with PAS positive granules, which also express A2B5/TE4 cell surface antigens and MHC Class I (HLA A, B, C) molecules. In contrast to the medullary RE cells, these subcapsular nurse cells also produce thymosins beta 3 and beta 4. The thymic nurse cells (TNCs) display a neuroendocrine cell specific immunophenotype (IP): Thy-1+, A2B5+, TT+, TE4+, UJ13/A+, UJ127.11+, UJ167.11+, UJ181.4+, and presence of common leukocyte antigen (CLA+). Medullar RE cells display MHC Class II (HLA-DP, HLA-DQ, HLA- DR) molecule restriction. These cells also contain transforming growth factor (TGF)-beta type II receptors and are involved in the positive selection of T cells. Transmission electronmicroscopic (TEM) observations have defined four, functional subtypes of medullary RE cells: undifferentiated squamous, villous and cystic. All subtypes were connected with desmosomes. The secreted thy nic hormones, thymulin, thymosin-alpha 1 and thymopoietin (its short form, thymopentin or TP5) were detected immunocytochemically to be produced by RE cells. Thymic RE cells also produce numerous cytokines including IL-1, IL-6, G-CSF, M-CSF, and GM-CSF molecules that likely are important in various stages of thymocyte activation and differentiation. The co-existence of pituitary hormone and neuropeptide secretion [growth hormone (GH), prolactin (PRL), adrenocorticotropic hormone (ACTH), thyroid stimulating hormone (TSH), triiodothyronine (T3), somatostatin, oxytocin (OT), follicle stimulating hormone (FSH), luteinizing hormone (LH), arginine vasopressin (AVP), growth hormone releasing hormone (GHRH), corticotropin releasing hormone (CRH), nerve growth factor (NGF), vasoactive intestinal peptide (VIP), pro-enkephalin (pro-enk), and beta-endorphin (beta-end)], as well as production of a number of interleukins and growth factors and expression of receptors for all, by RE cells is an unique molecular biological phenomenon. The thymic RE cell network is most probably comprised of cells organized into sub-networks--functional units composed of RE cells with differing hormone production/hormone receptor expression profiles, involved in the various stages of T lymphocyte maturation. Furthermore, it is quite possible that even on the level of individual RE cells, the numerous projections associated with a single cell, which engulf developing lymphocytes, nurturing and guiding them in their maturation, may differ in their hormone production and/or hormone receptor expression profile, thus allowing a single cell to be involved in distinct, separate steps of the T cell maturation process. Based on our systematic observations of the thymus in humans and other mammalian species, we suggest that the thymic RE cells represent an extremely important cellular and humoral network within the thymic microenvironment and are involved in the homeopathic regulation mechanisms of the multicellular organism, in addition to the presentation of various antigens to developing lymphocytes, and providing growth regulatory signals which may range from stimulatory to apoptotic signaling within the thymus. (ABSTRACT TRUNCA

Differentiation of promyelocytic leukemia cells HL-60 induced by daidzein in vitro and in vivo.

We have screened more than one thousand synthetic and natural chemicals to explore differentiation inducers and found that daidzein has potent differentiation-inducing activity for human leukemia HL-60 cells, both in vitro and in vivo. In vitro study showed that daidzein at concentrations exceeding 10 micrograms/ml caused inhibition of HL-60 cells; and it induced differentiation of the cells into granulocytic lineage as judged by NBT reduction activity, phagocytic ability and morphological characteristics. Flow cytometry study indicated that daidzein arrested HL-60 cells in the G1 phase. The growth of HL-60 cells in the subrenal capsules of mice and in diffusion chambers implanted into the peritoneal cavities of mice was inhibited by 50 mg/kg daidzein. HL-60 cells treated with daidzein in vivo also exhibited characteristic morphological changes of matured cells. Moreover, the colony forming efficiency of HL-60 cells in diffusion chambers in mice was markedly inhibited by the administration of daidzein.

[Effect of kanggusong in prevention and treatment of retinoic acid induced osteoporosis in rats].

Retinoic acid 70 mg/kg.d was given by gastrogavage to Wistar rat for 14 days to induce osteoporosis. Kanggusong (KGS), a mixture of extracts from 8 traditional Chinese drugs, was given to 3 test groups of rats simultaneously in various dosage. Results showed that the KGS displayed obvious action in preventing osteoporosis, the trabecular loss of tibiae and bone loss of compact bone were lowered markedly in KGS groups with high (3.0 g/kg.d) or middle (1.0 g/kg.d) dosage in comparing with control model group, the trabecular area percentage and compact bone area percentage were increased significantly (P < 0.05) which approached to the level of normal control group. KGS could also improve the pathological changes in microstructure of bone, increase the thickness of trabecula and cortex (P < 0.05), reduce the trabecular gap and bone marrow cavity (P < 0.05). The mechanism of KGS might be relevant with its action of suppressing the osteoclast activity and activating osteoblast, resulting a positive balance of bone metabolism, increasing the blood concentration of calcium and estrogen as well as its antagonistic action against the injury of sex glands by retinoic acid.

[Effects of realgar on tissue factor expression of NB4 and MR2 cells].

OBJECTIVE: To investigate the effects of Realgar on procoagulant activity (PCA), tissue factor expression and tissue factor mRNA transcription in acute promyelocytic leukemia (APL) cell lines NB4 and MR2 cells. METHOD: NB4 and MR2 cells were treated with 300 micrograms.L-1 Realgar PCA of the treated cells was detected using one-stage clotting assay. TF antigen was detected by ELISA and TFmRNA by semi-quantitive RT-PCR. RESULT: The PCA and TF antigen level in NB4 and MR2 cells were significantly higher than that in HL-60 and K562 cells. Realgar could down-regulate the membrane PCA, TF antigen and TF mRNA transcription of NB4 and MR2 cells in a time-dependent manner. CONCLUSION: Down-regulating TF expression and PCA of NB4 and MR2 cells by Realgar may be one of the mechanism of its improvement effect on DIC-related hemorrhage of APL patients.

[In vitro study on realgar induced apoptosis of all-trans acid resistant acute promeylocytic leukemia cell line (MR2)].

OBJECTIVE: To acquire a deep understanding of the possible mechanisms of realgar in the treatment of acute promyelocytic leukemia (APL). METHOD: All-trans retinoic acid (ATRA) resistant APL cell line MR2 was used as in vitro model. The effect of realgar on MR2 cell was observed by watching cell viability, cell growth, and by using Methy thiazolyl tetrazolium (MTT) assay, cell morphology, DNA gel electrophoresis and flow cytometry assay. RESULT: The viability and growth of MR2 cell were inhibited after the treatment, to some extent, in a dose and time dependent manner. After being treated with realgar, MR2 cell presented morphologically some features of apoptotic cells such as intact cell membrane, chromatin condensation and nuclear fragmentation, and apoptotic body could be found by electron microscopy as well. Sub-G1 cells were observed by flow cytometry, as well as Annexin V FITC+/PI-cells. DNA ladder could be found by DNA gel electrophoresis. CONCLUSION: Realgar can induce apoptosis of ATRA resistant APL cell line MR2, Which shows the therapeutic effect of realgar on APL may be different from that of ATRA.

Regulation of androgen receptor gene expression by steroids and retinoic acid in human breast-cancer cells.

Although the androgen receptor (AR) has been detected by ligand-binding assays, there is little known about the expression and regulation of the AR gene in human breast-cancer cells. AR mRNA, measured by Northern analysis in 18 cell lines, was found to be expressed predominantly in oestrogen- and progesterone-receptor-positive (ER+, PR+) lines as a single species of approximately 10.5 kb but was also comparatively abundant in I ER- and PR-negative cell line, MDA-MB-453. Dexamethasone (Dex), Organon 2058 (Org 2058), dihydrotestosterone (DHT), and all-trans-retinoic acid (RA) down-regulated AR mRNA levels in T-47D (ER+, PR+) cells 6 hr after treatment, whereas oestradiol (E2) had no effect. In MDA-MB-453 (ER-, PR-) cells, regulation of AR mRNA by RA differed from the other cell lines: RA increased the level of AR mRNA. DHT-binding assays indicated a corresponding increase in AR protein. Transfection of the androgen-responsive mouse mammary tumour virus long-terminal repeat (MMTV LTR) linked to a chloramphenicol acetyltransferase (CAT) reporter gene was used to examine the effect of altered AR levels on androgen action. The increased level of AR following RA pre-treatment in MDA-MB-453 cells resulted in enhanced induction of CAT activity by DHT and, conversely, a decrease in the level of AR following RA pretreatment in T-47D cells resulted in reduced induction of CAT activity by DHT. These data demonstrate that AR is expressed predominantly in ER+ and PR+ cell lines and its expression is regulated by ligands also known to regulate ER or PR, including progestins and retinoids. Androgen responsiveness measured by a transfected reporter gene was altered according to the extent of up- or down-regulation of AR expression, demonstrating that responsiveness is dependent on receptor concentration.