OBJECTIVETo explore the molecular mechanism of APL cell resistance to ATRA.

METHODSThe ATRA sensitive and resistant APL cell lines, NB4 and NB4-R1, were used as in vitro models. The effects of specific inhibitors and activators of adenylate cyclase (AC) and phosphodiesterase (PDE) on ATRA-induced differentiation was evaluated by cell morphology, cell surface antigen expression and nitroblue-tetrazolium (NBT) reduction assays.

RESULTSSQ22536, a specific antagonist of AC, could dramatically block ATRA-induced NB4 cell differentiation. When ATRA + SQ22536 group compared with ATRA group, the positivity of CD11b decreased from (95.9 +/- 2.5)% to (60.3 +/- 7.1)%, while the A(540) in NBT reduction assay decreased from 0.585 +/- 0.092 to 0.170 +/- 0.028 (P < 0.05). Forskolin, an agonist of AC, could overcome the resistance of NB4-R1 cells to ATRA. When ATRA + forskolin group compared with ATRA group, the positivity of CD11b increased from (34.3 +/- 5.3)% to (94.6 +/- 2.4)%, while the A(540) in NBT reduction assay increased from 0.110 +/- 0.028 to 0.395 +/- 0.049 (P < 0.05). In contrast, the specific antagonist and agonist of PDE, 3-isobutyl-1-methylxanthine (IBMX) and calmodulin, exerted little impact on ATRA treatment.

CONCLUSIONSThe defaults in the initiation of AC activation may contribute to the resistance to ATRA in some APL cells.

Adenine ; analogs & derivatives ; pharmacology ; Adenylyl Cyclase Inhibitors ; Adenylyl Cyclases ; metabolism ; Antineoplastic Agents ; pharmacology ; CD11b Antigen ; metabolism ; Cell Differentiation ; drug effects ; Cell Line, Tumor ; Drug Resistance, Neoplasm ; drug effects ; Enzyme Activation ; drug effects ; Enzyme Inhibitors ; pharmacology ; Humans ; Leukemia, Promyelocytic, Acute ; metabolism ; pathology ; Phosphoric Diester Hydrolases ; metabolism ; Tretinoin ; pharmacology

BACKGROUND/OBJECTIVES: This study evaluated the effects and molecular mechanisms of the Schisandra chinensis fruit extract (SC) and its major compound gomisin A (GA), on the contractility of rabbit penile corpus cavernosum smooth muscle (PCCSM). MATERIALS/METHODS: PCCSM was exposed to SC or GA after appropriate pretreatment with nitric oxide synthase (NOS) blocker, guanylate cyclase blocker, adenylyl cyclase blocker or protein kinase A blocker. Subsequently, we evaluated the cyclic nucleotide in the perfusate by radioimmunoassay, protein expression level of neuronal NOS (nNOS) and endothelial NOS (eNOS) by western blot, and the interaction of SC or GA with udenafil and rolipram. RESULTS: Both SC and GA induce PCCSM relaxations in a concentration-dependent manner. Pretreatment with NOS blocker, guanylate cyclase blocker, adenylyl cyclase blocker or protein kinase A blocker result in significantly decreased relaxation. SC and GA also induce the levels of cyclic nucleotide in the perfusate in a concentration-dependent manner. Perfusion with GA also showed significantly higher levels of eNOS protein. Furthermore, the udenafil and rolipram induced relaxations of PCCSM were enhanced after exposure to SC and GA. Our results indicate that SC and GA induce the relaxation of PCCSM via the nitric oxide (NO)-cGMP and cAMP signaling pathways. CONCLUSIONS: The SC and GA are potential alternative treatments for men who want to consume natural products to ameliorate erectile function, or who do not respond to the commercially available medicines.
Adenylyl Cyclases ; Biological Products ; Blotting, Western ; Cyclic AMP-Dependent Protein Kinases ; Erectile Dysfunction ; Fruit* ; Guanosine Monophosphate* ; Guanosine* ; Guanylate Cyclase ; Humans ; Lignans ; Male ; Muscle, Smooth* ; Neurons ; Nitric Oxide Synthase ; Nitric Oxide* ; Perfusion ; Phosphodiesterase 5 Inhibitors ; Radioimmunoassay ; Relaxation ; Rolipram ; Schisandra*

Retaining or improving periodontal ligament (PDL) function is crucial for restoring periodontal defects. The aim of this study was to evaluate the physiological effects of low-power laser irradiation (LPLI) on the proliferation and osteogenic differentiation of human PDL (hPDL) cells. Cultured hPDL cells were irradiated (660 nm) daily with doses of 0, 1, 2 or 4 J⋅cm(-2). Cell proliferation was evaluated by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay, and the effect of LPLI on osteogenic differentiation was assessed by Alizarin Red S staining and alkaline phosphatase (ALP) activity. Additionally, osteogenic marker gene expression was confirmed by real-time reverse transcription-polymerase chain reaction (RT-PCR). Our data showed that LPLI at a dose of 2 J⋅cm(-2) significantly promoted hPDL cell proliferation at days 3 and 5. In addition, LPLI at energy doses of 2 and 4 J⋅cm(-2) showed potential osteogenic capacity, as it stimulated ALP activity, calcium deposition, and osteogenic gene expression. We also showed that cyclic adenosine monophosphate (cAMP) is a critical regulator of the LPLI-mediated effects on hPDL cells. This study shows that LPLI can promote the proliferation and osteogenic differentiation of hPDL cells. These results suggest the potential use of LPLI in clinical applications for periodontal tissue regeneration.
Adenine ; analogs & derivatives ; pharmacology ; Adenylyl Cyclase Inhibitors ; Alkaline Phosphatase ; analysis ; genetics ; radiation effects ; Anthraquinones ; Bone Morphogenetic Protein 2 ; genetics ; Calcium ; metabolism ; radiation effects ; Cell Culture Techniques ; Cell Differentiation ; radiation effects ; Cell Line ; Cell Proliferation ; radiation effects ; Coloring Agents ; Core Binding Factor Alpha 1 Subunit ; genetics ; Cyclic AMP ; antagonists & inhibitors ; radiation effects ; Gene Expression ; radiation effects ; Humans ; L-Lactate Dehydrogenase ; analysis ; Lasers, Semiconductor ; Low-Level Light Therapy ; instrumentation ; Osteocalcin ; genetics ; Osteogenesis ; genetics ; radiation effects ; Periodontal Ligament ; cytology ; radiation effects ; Radiation Dosage ; Real-Time Polymerase Chain Reaction ; Reverse Transcriptase Polymerase Chain Reaction ; Tetrazolium Salts ; Thiazoles