316 INTERNATIONAL JOURNAL OF ONCOLOGY 49: 316-324, 2016 Ophiopogonin B induces apoptosis, mitotic catastrophe and autophagy in A549 cells MEIJUAN CHEN1,2, YUANYUAN GUO1,2, RUOLIN ZHAO1, XIAOXIA WANG2, MIAO JIANG1, HAIAN FU3,4 and XU ZHANG2 1The Pre-Clinical Medicine College and 2Jiangsu Collaborative Innovation Center of Traditional Chinese Medicine (TCM) Prevention and Treatment of Tumor, Nanjing University of Chinese Medicine, Nanjing 210023, P.R. China; Departments of 3Pharmacology and 4Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA 30322, USA Received February 27, 2016; Accepted April 9, 2016 DOI: 10.3892/ijo.2016.3514 Abstract. Ophiopogonin B (OP-B), a saponin compound of p-Histone H3 (Ser10), Survivin and XIAP further indicated isolated from Radix Ophiopogon japonicus, was verified to the molecular mechanism of OP-B in vivo. As our findings inhibit cell proliferation in numerous non-small cell lung revealed, multiple types of cell death overlapped in OP-B cancer (NSCLC) cells in our previous study. However, the treated A549 cells, it displayed multitarget characteristics of precise mechanisms of action have remained unclear. In the the compounds extracted from the Chinese herbal, which may present study, we mainly investigated the effects of OP-B on be used as candidate anticancer medicine in clinic. adenocarcinoma A549 cells to further elaborate the underlying mechanisms of OP-B in different NSCLC cell lines. Detection Introduction by high content screening (HCS) and TUNEL assay verified that OP-B induced apoptosis in this cell line, while detection Lung cancer is one of the leading causes of cancer-related of Caspase-3, Bcl-2 and Bax showed that OP-B induced cell deaths in the world. Non-small cell lung cancer (NSCLC) death was caspase and mitochondrial independent. Further accounts for nearly 85% in all lung cancer cases, with adeno- experiments showed that OP-B induced cell cycle arrest in carcinoma, squamous cell carcinoma and large cell carcinoma the S and G2/M phases by inhibiting the expression of Myt1 being the main histological subtypes (1). Current clinical treat- and phosphorylation of Histone H3 (Ser10), which resulted in ments such as surgery, radiotherapy and chemotherapy are still mitotic catastrophe in the cells. Transmission electron micros- insufficient for NSCLC-treatment (2,3) and new therapeutics copy (TEM) observation of cell micro-morphology combined need to be developed. with detection of Atgs by western blot analysis showed that Traditional Chinese Medicine is efficient in improving OP-B induced autophagy in this cell line. Autophagy inhibition clinical symptoms, regulating tumor growth and preventing by the lysosome inhibitor CQ or Beclin1-siRNA knockdown the recurrence of lung cancer in patients. In our previous study, both attenuated cell viability, demonstrated that autophagy we found that the “Ke Jinyan Priscription”, given by the State also being the vital reason resulted in cell death. More impor- Medical Master Zhou Zhongying, inhibited the proliferation tantly, the xenograft model using A549 cells provided further of NCI-H157 or A549 transplanted tumors, respectively, in evidence of the inhibition of OP-B on tumor proliferation. nude mice, and the physical status of the animals was signifi- Immunohistochemistry detection of LC3 and Tunel assay cantly improved (4). Some ingredients extracted from the both verified that high dose of OP-B (75 mg/kg) induced formula showed significant inhibitory effects on NSCLC cell autophagy and apoptosis in vivo, and western blot detection lines under screening on the high-throughput platform (5,6). In particular, one of the derived compounds, ophiopogonin B (OP-B), showed especially potent inhibition of a series of NSCLC cell lines, and in H157 and H460 cell lines it mainly Correspondence to: Dr Haian Fu, Department of Pharmacology, induced autophagic cell death which was caspase-indepen- Emory University School of Medicine, Atlanta, GA 30322, USA dent (7). E-mail: [email protected] Besides autophagy, the caspase-independent programmed cell death (PCD) includes paraptosis, mitotic catastrophe, and Dr Xu Zhang, Jiangsu Collaborative Innovation Center of Traditional the descriptive model of apoptosis-like and necrosis-like PCD. Chinese Medicine (TCM) Prevention and Treatment of Tumor, Nanjing University of Chinese Medicine, Nanjing 210023, P.R. China Once caspase-mediated routes fail in vivo, caspase-indepen- E-mail: [email protected] dent cell death pathways are important for cleaning unwanted or harmful cells, which can also be triggered by cytotoxic Key words: ophiopogonin B, apoptosis, mitotic catastrophe, autophagy, agents or other death stimuli (8). As potentially new cancer cell cycle, histone H3 therapies could be developed, the growing knowledge of the caspase-independent cell death pathways is very important for oncology research (8). CHEN et al: Ophiopogonin B induces apoptosis, mitotic catastrophe and autophagy in A549 cells 317 To establish whether OP-B triggered different types of (Thermo Fisher Scientific, Waltham, MA, USA). The prin- caspase-independent cell death in NSCLC cell lines, herein, ciple of the assay is that cells are labeled with a cocktail of we tested its effects on human lung adenocarcinoma A549 fluorescent dyes (including Hoechst 33258 and Alexa Fluor cells. The results revealed that OP-B induced mitotic catas- 488 Annexin V) that indicate the cellular properties of trophe in A549 cells in vitro, and the mechanism may due interest, including nuclear structure, cell membrane perme- to the inhibition of Myt1 and p-Histone H3 (Ser10) and the ability, as well as early and late stages of apoptosis. All specific regulation of the cell cycle, combined with induction procedures were performed according to the manufacturer's of autophagy, it resulted in caspase-independent apoptosis in instructions. The cells were plated at a density of 8x103 cells/ this cell line. Moreover, OP-B inhibited expression of XIAP, well in each well of a 96-well plate. After culturing for 24 h, survivin and the phosphorylation of Histone H3 (Ser10), cells were incubated with 10 µM OP-B for another 24 h. thereby induced autophagy and apoptosis in vivo. Compared Thirty minutes before the completion of incubation, a cock- with its effects on H157 and H460 cells, the investigation tail of fluorescent dyes was added to each well. The cells were demonstrated that OP-B may be more efficient in treating then fixed with pre-warmed fixation solution and washed A549 cells. twice with PBS. Plates were then sealed and processed on an HCS Reader to acquire images. Images were analyzed with Materials and methods HCS software, and fluorescence intensities of the Hoechst 33258 and Annexin V/PI dyes were calculated. As for DAPI Reagents. Ophiopogonin B (OP-B) (MW: 722.9, HPLC ≥98%) staining, the cells were cultured and treated and detected by was purchased from Nanjing Zelang Medical Technology Co., HCS as above. Ltd. (Nanjing, China). The chemicals used were staurosporine, chloroquine (CQ), propidium iodide (PI), (3-(4,5-dimethyl- Western blot analysis. After treatment with different thiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT), DAPI concentrations of OP-B, the cells were lysed in RIPA buffer and Hoechst 33258 (Sigma-Aldrich, St. Louis, MO, USA). containing 50 mmol/l Tris-HCl (pH 8.0), 150 mmol/l NaCl, 1% The Alexa Fluor 488 Annexin V/Dead Cell apoptosis kit Nonidet-P40, 1% sodium deoxycholate, 0.1% SDS, 0.1 mmol/l (Invitrogen, Waltham, MA, USA) and the In Situ Cell Death DTT, 0.05 mmol/l PMSF, 0.002 mg/ml aprotinin, 0.002 mg/ml Detection kit (Roche, Indianapolis, IN, USA) were also leupeptin and 1 mmol/l NaVO3. The protein concentrations obtained commercially. of supernatants were determined by the BCA protein assay. Equal amounts of protein were loaded and separated by 10 Cell culture and transient transfection. The human or 12% SDS-PAGE and then transferred onto polyvinylidene NSCLC cell line (A549) was obtained from the Institute of difluoride membranes. The membranes were incubated over- Biochemistry and Cell Biology (Shanghai, China). The A549 night with appropriate primary antibodies against LC3 I/II, cells were cultured in Dulbecco's modified Eagle's medium Beclin-1, Atg3, Atg-5/12, p-Histone H3 (Ser10), caspase-3, (DMEM) and F12 medium (HyClone Laboratories, Logan, Bcl-2, Bax, cyclin D1, cyclin D3, CDK4, CDK6, cyclin A2, UT, USA), respectively, supplemented with 10% fetal bovine CDK2, cyclin B1, Myt1, p-cdc2, p21, p27, survivin, XIAP serum (FBS; Gibco, Waltham, MA, USA), 100 U/ml peni- or β-actin overnight at 4˚C, and then with HRP-conjugated cillin-streptomycin mixed antibiotics at 37˚C in a humidified secondary antibodies (anti-rabbit or mouse immunoglobulin G) 5% CO2 incubator. for an additional hour at room temperature. Immunoreactivity For transient transfection, A549 cells were seeded in 6-cm was detected by enhanced chemiluminescence (ECL; Bio-Rad culture dishes at a density of 106 cells/dish and then transfected Laboratories, Hercules, CA, USA). β-actin was used as a with rat Beclin1 siRNAs (C-300506-03-0005; Dharmacon, loading control. Immunoblot experiments were performed Lafayette, CO, USA) using Lipofectamine 2000 reagent at least three times. Image acquisition was performed using (13778-075; Invitrogen) according to the manufacturer's Image Lab™ software. protocol. Immunohistochemistry assay. The immunohistochemistry for Transmission electron microscopy (TEM). After being LC3 localization in the tumor was performed as previously exposed to 10 µM of OP-B for 48 h, the cells were trypsinized, described (9). washed with phosphate-buffered saline (PBS) and fixed in 2.5% glutaraldehyde in 0.1 M phosphate buffer (pH 7.2) over- Terminal deoxynucleotidyltransferase-mediated dUTP nick night at 4˚C. The next day, cells were washed three times with end labeling (TUNEL) assay. TUNEL staining was performed 0.1 mol/l phosphate buffer. Thereafter, the cells were fixed in by using the ‘In Situ Cell Death Detection kit’ from Roche 1% aqueous osmium, dehydrated with increasing concentra- following the manufacturer's instructions.