ABSTRACT
Eleven undescribed cembrane-type diterpenoids, named litoamentenes A-K (1-11), were isolated from the soft coral Litophyton amentaceum collected from the South China Sea. Their structures were elucidated by extensive analysis of spectroscopic data, comparison with the literature data, single crystal X-ray diffraction, quantum chemical calculations and TDDFT-ECD calculations. This is the first systematic investigation of L. amentaceum. In particular, compounds 1-3 are cembrane-type norditerpenoids that lack isopropyl side chains. Compound 6 is a cembrane-type norditerpenoid without a methyl group at C-4, the first natural product identified with this carbon skeleton. Compounds 6, 9 and 10 showed modest cytotoxicity against several human cancer cell lines with IC50 values ranging from 3.99 to 14.56 µM.
Subject(s)
Anthozoa , Diterpenes , Drug Screening Assays, Antitumor , Anthozoa/chemistry , Diterpenes/chemistry , Diterpenes/pharmacology , Diterpenes/isolation & purification , Animals , Humans , Molecular Structure , Structure-Activity Relationship , Antineoplastic Agents/pharmacology , Antineoplastic Agents/chemistry , Antineoplastic Agents/isolation & purification , China , Cell Line, Tumor , Cell Proliferation/drug effects , Dose-Response Relationship, Drug , Models, MolecularABSTRACT
OBJECTIVE: to investigate the antitumor effects of tumstatin185-191 as a single agent or combination with cisplatin (DDP) on non-small lung cancer (NSCLC) cell lines A549. In addition, the changes of the protein kinase B(Akt) and extracellular regulated protein kinase (ERK) in cultured NSCLC cells treated by tumstatin185-191 and cisplatin were evaluated. METHODS: A549 cells were treated with tumstatin185-191 and cisplatin. Cell viability was assessed using the modified 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell apoptosis was measured by flow cytometry. The activation of Akt and Erk were evaluated by Western blotting. RESULTS: Tumstatin185-191 inhibited the proliferation of A549 and the IC(50) values of tumstatin 185-191 was 73.7 micromol/L. After cotreatment with 20 micromol/L tumstatin185-191, IC(50) values of cisplatin in A549 cells reduced from 5.2 micromol/L to 3.5 micromol/L, while 40 micromol/L tumstatin185-191 reduced from 5.2 micromol/L to 1.4 micromol/L. The early apoptosis rate was (19.34 +/- 0.97)% in the cotreatment group, (12.5 +/- 2.1)% in cisplatin group and (9.6 +/- 1.6)% in tumstatin185-191 group (F = 5.74, P < 0.01). The levels of phospho-Akt (p-Akt) and phospho-ERK (p-ERK) in the A549 cells were remarkably lower after being treated with tumstatin 185-191, while tumstatin 185-191 treatment whether alone, or in combination with cisplatin, had the similar effects on the protein levels of p-Akt and p-ERK in A549 cells. CONCLUSION: our data suggest that tumstatin185-191 might enhance the sensitivity of A549 cells to cisplatin. The effects of promoting apoptosis and downregulation of proliferation induced by tumstatin185-191 may be mediated through inactivation of the Akt and ERK pathways.
Subject(s)
Adenocarcinoma/metabolism , Autoantigens/pharmacology , Collagen Type IV/pharmacology , Extracellular Signal-Regulated MAP Kinases/metabolism , Lung Neoplasms/metabolism , Proto-Oncogene Proteins c-akt/metabolism , Adenocarcinoma/pathology , Adenocarcinoma of Lung , Apoptosis , Autoantigens/administration & dosage , Cell Line, Tumor/drug effects , Cell Proliferation/drug effects , Cisplatin/administration & dosage , Cisplatin/pharmacology , Collagen Type IV/administration & dosage , Humans , Lung Neoplasms/pathologyABSTRACT
OBJECTIVE: To investigate the effects and related mechanisms of Tumstatin 185-191 as a single agent or in combination with cisplatin on proliferation and apoptosis in a cisplatin-resistant human lung adenocarcinoma cell line A549-DDP cells. METHODS: A549-DDP cells were treated with Tumstatin185-191 and cisplatin at varying concentrations. Cell viability was assessed by a modified 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. 50% inhibiting concentration (IC(50)) values of the chemotherapeutic drugs were analyzed by MTT assay. Cell apoptosis was measured by flow cytometry. The activation of Akt and ERK was evaluated by Western blotting. RESULTS: Tumstatin185-191 inhibited the proliferation of A549-DDP cells and its IC(50) value was 80.25 micromol/L. After cotreatment with 20 micromol/L Tum185-191, the IC(50) value of cisplatin in A549-DDP cells reduced from 77.16 micromol/L to 57.97 micromol/L, the reverse index was 1.33, while with 40 micromol/L Tumstatin185-191 the IC(50) was reduced from 77.16 to 26.40 micromol/L and the reverse index was 2.92. The early apoptosis rate was 19.5% +/- 1.1% in the cotreatment group, while 13.3% +/- 1.5% in cisplatin group and 10.2% +/- 2.0% in Tum185-191 group (F = 4.09, P < 0.05). The levels of phospho-Akt (p-Akt) and phospho-ERK (p-ERK) in the A549-DDP cells were remarkably lower after treatment with Tumstatin 185-191. The Tumstatin 185-191 treatment alone or in combination with cisplatin had a similar effect on the protein levels of p-Akt and p-ERK in A549-DDP cells. CONCLUSION: Our data suggest that Tumstatin185-191 may promote apoptosis, downregulate proliferation and partly reverse the drug resistance of A549-DDP cells to cisplatin. The effects induced by Tum185-191 may be mediated through inactivation of the Akt and ERK pathways.
Subject(s)
Adenocarcinoma/pathology , Apoptosis/drug effects , Autoantigens/pharmacology , Cell Proliferation/drug effects , Collagen Type IV/pharmacology , Lung Neoplasms/pathology , Antineoplastic Agents/pharmacology , Cell Line, Tumor , Cisplatin/pharmacology , Drug Resistance, Neoplasm , Drug Synergism , Extracellular Signal-Regulated MAP Kinases/metabolism , Humans , Peptide Fragments/pharmacology , Phosphorylation , Proto-Oncogene Proteins c-akt/metabolismABSTRACT
OBJECTIVE: To explore the effect of cyclooxygenase-2 on vascular endothelial cell apoptosis induced by cigarette smoke extract. METHODS: Human vascular endothelial cells (ECV-304) were cultured in vitro, and those at the exponential growth phase were studied in experiments. The experiment was completed through 3 steps: (1) ECV-304 cells were cultured with 0.0%, 0.5%, 1.0% and 5.0% CSE for 12 h. (2) ECV-304 cells were exposed to 5.0% CSE for 0, 3, 6, 9, 12 and 24 h. (3) Endothelial cells were treated by 5% CSE, together with different concentrations of selective COX-2 inhibitor celecoxib (0.0, 2.5, 5.0, 10.0, 20.0, 50.0 micromol/L concentrations) for 9 h. The cell apoptosis rate was tested by Hoechst staining and flow cytometry methods, and the expression of COX-2 protein by immunocytochemistry and Western blotting. RESULTS: CSE induced ECV-304 cell apoptosis and COX-2 expression in a dose-dependent manner. The apoptosis rate of ECV-304 cells with 5.0% CSE was the highest (5.40+/-0.39)%. CSE- induced COX-2 expression reached the highest level with 5.0% CSE (206.1+/-15.5), the differences being significant (F=90.03, 159.94, all P<0.05). Furthermore CSE induced both apoptosis rate and COX-2 expression time-dependently, with the apoptosis rate achieving the peak after 24 h (8.87+/-0.41)%, while COX-2 expression reached the highest level at 9 h. The selective COX-2 inhibitor celecoxib inhibited COX-2 protein expression partially and augmented cell apoptosis induced by CSE. CONCLUSIONS: CSE induces endothelial cell apoptosis and increases the expression of COX-2 protein in vascular endothelial cells. Celecoxib, the selective COX-2 inhibitor, reduces the expression of COX-2 protein and promotes cell apoptosis induced by CSE in vascular endothelial cells. COX-2 may play an important role in protecting development of CSE-associated apoptosis of endothelial cells.
