Here, we identified 24-methylenecyloartanyl ferulate (24-mCAF) as the main component ..... by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-.
Cite This: J. Agric. Food Chem. 2018, 66, 3726−3733
Cytotoxic Eﬀects of 24-Methylenecyloartanyl Ferulate on A549 Nonsmall Cell Lung Cancer Cells through MYBBP1A Up-Regulation and AKT and Aurora B Kinase Inhibition Soﬁa Doello,†,§ Zhibin Liang,† Il Kyu Cho,†,‡ Jung Bong Kim,†,# and Qing X. Li*,† †
Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States Interfaculty Institute of Microbiology and Infection Medicine Tübingen, University of Tübingen, Tübingen 72076, Germany ‡ BioControl Research Center, Jeonnam Bioindustry Foundation, Gokseong 57509, Korea # Department of Agro-Food Resources, National Institute of Agricultural Sciences, Rural Development Administration, Jeonju 55365, Korea §
S Supporting Information *
ABSTRACT: Lung cancer is the second most prevalent cancer. Nonsmall cell lung cancer (NSCLC) is the most common type of lung cancer. The low eﬃcacy in current chemotherapies impels us to ﬁnd new alternatives to prevent or treat NSCLC. Rice bran oil is cytotoxic to A549 cells, a NSCLC cell line. Here, we identiﬁed 24-methylenecyloartanyl ferulate (24-mCAF) as the main component responsible for the cytotoxicity in A549 cells. An iTRAQ-based quantitative proteomics analysis revealed that 24-mCAF inhibits cell proliferation and activates cell death and apoptosis. 24-mCAF induces up-regulation of Myb binding protein 1A (MYBBP1A), a tumor suppressor that halts cancer progression. 24-mCAF inhibits the activity of AKT and Aurora B kinase, two Ser/Thr kinases involved in MYBBP1A regulation and that represent important targets in NSCLC. This study provides the ﬁrst insight of the eﬀect of 24-mCAF, the main component of rice bran oil, on A459 cells at the cellular and molecular levels. KEYWORDS: 24-methylenecyloartanyl ferulate, oryzanol, iTRAQ, nonsmall cell lung cancer, rice bran, quantitative proteomics
INTRODUCTION Lung cancer is the leading cause of cancer death in men and women. In 2018, lung and bronchus cancers are expected to cause approximately 25% of the cancer deaths in the United States. It is the second most commonly diagnosed cancer, accounting for 14% of the new cases, and its prevalence keeps increasing worldwide each year.1 Nonsmall cell lung cancer (NSCLC) is the most common type of lung cancer, representing about 85% of the cases. The two most commonly mutated oncogenes in NSCLC are the epidermal growth factor receptor (EGFR) and Kirsten rat sarcoma (KRAS). Mutations in these two genes are mutually exclusive in NSCLC. When EGFR is overexpressed, it causes cells to grow in a faster and uncontrolled way. Erlotinib and geﬁtinib are epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) that block the signal from the overexpressed EGFR and that are used as a treatment for NSCLC. KRAS encodes a GTPase downstream of EGFR which signals through the PI3K/AKT/mTOR and STAT pathways involved in cell survival and the RAS/RAF/MEK/MAPK pathway (also known as the MAPK/ERK pathway) involved in cell proliferation. KRAS mutations also result in uncontrolled growth. Cells presenting KRAS mutations are not sensitive to treatment with TKIs drugs such as erlotinib and geﬁtinib. General cancer treatments, such as surgery, chemotherapy, and radiotherapy, are usually applied to NSCLC patients with KRAS mutations because there is no targeted therapy available.2,3 KRAS is one of the most diﬃcult drug targets, © 2018 American Chemical Society
and although some KRAS inhibitors have been reported in the past few years, the design of eﬀective drugs remains a big challenge. KRAS mutations occur in approximately 33% of NSCLCs, and the prognosis for this type of cancer is very poor. There is a great need for the development and implementation of a novel, eﬀective, and aﬀordable treatment and prevention for this kind of cancer.4 Plant extracts have been widely used in traditional medicine for centuries. Nowadays, the use of bioactive phytochemicals and nutraceuticals is gaining attention due to their low cost, low toxicity, high tolerability, and reported health beneﬁts.5 Rice is the most important staple food. Rice bran oil is cytotoxic to A549 cells, a human adenocarcinoma epithelial cell line that carries KRAS mutations.6 γ-Oryzanol is a mixture of ferulate esters of triterpene alcohols and plant sterols that constitutes the major component of rice bran oil, representing about 4% of the crude extract. γ-Oryzanol has numerous beneﬁts for human health, including cholesterol lowering capacity and antioxidant, anti-inﬂammatory, and cytotoxic eﬀects.7−10 The cytotoxic properties of γ-oryzanol have been tested in various cancer cell lines and animal models. In the prostate cancer cell lines DU145 and PC3, γ-oryzanol inhibits cell growth by downregulating genes involved in oxidative stress protection and cell Received: Revised: Accepted: Published: 3726
January 26, 2018 March 14, 2018 March 16, 2018 March 16, 2018 DOI: 10.1021/acs.jafc.8b00491 J. Agric. Food Chem. 2018, 66, 3726−3733
Journal of Agricultural and Food Chemistry Table 1. Compositionof γ-Oryzanol, Modiﬁed from Kim et al.14
10, 25, 50, and 75 μM. DMSO was used as a solvent carrier for γoryzanol; the ﬁnal concentration of DMSO in each condition was 0.75% v/v. There were three biological replicates of each treatment. Cells were treated for 72 h and then incubated with 200 μL of 500 μg/ mL MTT for 4 h. The supernatant was removed after centrifugation at 2000 rpm for 10 min. An aliquot of 200 μL of DMSO was added, and the optical density was then read at 550 nm (OD550). Protein Extraction. Cells were plated in complete DMEM in 75 cm2 culture ﬂasks. When the cells reached approximately 50% conﬂuence, they were starved with 0.05% v/v FBS for 24 h. The cells were treated with 50 μM 24-mCAF for 72 h, and a control culture was treated with DMSO (the total amount of DMSO in both conditions was 0.5% v/v). Four biological replicates of each condition were used. After 72 h of treatment, the cells were harvested using a cell scraper and washed 3 times with PBS, centrifuging at 2000 rpm for 10 min each time. Pellets were resuspended in 0.5 mL lysis buﬀer (10 mM Tris, pH 7.4, 100 mM NaCl, 1 mM EDTA, 2 mM Na3VO4, 1 mM EGTA, 1 mM NaF, 20 mM Na4P2O7, 1% v/v Triton X-100, 10% v/v glycerol, 0.1% v/v SDS, 0.5% v/v deoxycholate, and Halt protease inhibitor cocktail) and incubated for 30 min, mixing on a vortex every 10 min. Lysates were then sonicated in ice using an ultrasonic cell disruptor for 15 s, 3 times, waiting 2 min in between, and centrifuged for 10 min at 13 000 rpm and 4 °C. The supernatant was transferred to a clean tube. Protein concentration was measured according to the Bradford method. Samples were diluted 1:8 and 4 μL were mixed with 200 μL of BioRad Protein Assay Dye diluted 1:5 in a 96-well microtiter plate. BSA was used as a calibrator. Absorbance was read at 595 nm. Buﬀer Exchange and Sample Concentration. In order to avoid interference of components from the lysis buﬀer with the iTRAQ labeling reaction, the buﬀer was exchanged to 1 M TEAB pH 8.5 using an Amicon Ultra-0.5 mL 3K centrifugal ﬁlter. The sample was concentrated to 100 μL. Protein Digestion. One hundred micrograms of each sample (4 controls and 4 treatments) were transferred to new tubes. The volume was adjusted to 20 μL with TEAB buﬀer. Proteins were denatured and reduced using 0.05% v/v SDS and 5 mM tris(2-carboxyethyl) phosphine and incubating at 60 °C for 1 h. Cysteine residues were alkylated with methylmethanethiosulfate (10 mM) for 10 min at room temperature. Proteins were digested by adding 5 μg of sequencinggrade modiﬁed porcine trypsin resuspended in water and incubating at 37 °C for 14 h. iTRAQ-Labeling. iTRAQ-8plex reagents were resuspended in 50 μL of isopropanol, added to the samples, and allowed to react for 2 h at room temperature. Labels 113, 114, 115, and 119 were used on the control samples; labels 116, 117, 118, and 121 were used on the treated samples. After labeling, samples were pooled together and TEAB buﬀer was evaporated on a SpeedVac, adding water (20 μL) to avoid dryness. The sample was then resuspended in 100 μL of SCX-A (7 mM KH2PO4, 30% acetonitrile, pH 2.65), and pH was adjusted with phosphoric acid to 1 is considered to be activated function and a z-score < −1 is considered to be inactivated. cNumbers indicate the amount of detected diﬀerentially expressed proteins involved in this function; arrows indicate up- (↑) or down-regulation (↓); a letter code indicates the protein accession number.
treated with 50 μM of 24-mCAF for 72 h. Four biological replicates of each condition were analyzed, each of them marked with a diﬀerent iTRAQ label. We identiﬁed a total of 484 proteins, from which 432 were consistently expressed in the control samples and were accepted for analysis (Supporting Information Figure S-1). A 1.25-fold cutoﬀ was established according to the procedure described by Unwin et al.17 This cutoﬀ was used to determine which proteins were diﬀerentially expressed. Distribution of the ratios is shown in Figure S-2. A total of 58 diﬀerentially expressed proteins were identiﬁed, 29 of which were up-regulated and 29 down-regulated (Supporting Information Table S-1). Diﬀerentially expressed proteins were subjected to IPA. The results revealed that 32 of them were cytoplasmic proteins, 18 were nuclear proteins, 6 were plasma membrane proteins, and 2 were extracellular proteins. Among these proteins, 20 were enzymes, 9 were transcription factors, and 5 were transporters (data not shown). Cellular function analyses indicated that cell death, apoptosis and cell proliferation were the most aﬀected cellular processes by 24-mCAF (Table 2). Cell death and apoptosis were activated, whereas cell proliferation was inactivated. Overall, 18 of the diﬀerentially expressed proteins contributed to the activation of cell death, 14 to the activation of apoptosis, and 11 to the inactivation of cell proliferation. MYBBP1A Is Up-Regulated by γ-Oryzanol. Several diﬀerentially expressed proteins relevant to oncology were downstream of MYBBP1A, a transcriptional regulator that was up-regulated by 24-mCAF. MYBBP1A acts as a tumor suppressor by binding to several proteins involved in cancer progression. These proteins include p53, NFκB, and sirtuin 6 (SIRT6). p53 is a transcription factor well-known for its role in cell cycle control; its interaction with MYBBP1A allows its activation and induces cell cycle arrest and apoptosis. NFκB controls inﬂammatory processes and cell survival; MYBBP1A inhibits the transcription of NFκB, leading to inhibition of these processes. SIRT6 is a deacylase known to act as a metastasisinducing protein in NSCLC. It inactivates a series of transcription factors that control the expression of a large number of proteins, including the tumor protein D52 (TPD52), NADH dehydrogenase ubiquinone 1 beta subcomplex subunit 9 (NDUFB9), fumarate hydratase (FH), malate dehydrogenase (MDH1), vesicle-traﬃcking protein SEC22B, and SEC23A. These 8 proteins, which are downstream MYBBP1A, were diﬀerentially expressed after treatment with 24-mCAF and their up- or down-regulation is consistent with MYBBP1A up-regulation. TPD52 and SEC22B are typically overexpressed in NSCLC; they act to induce cell migration and invasion, and they were down-regulated by 24mCAF. NDUFB9, FH, and SEC23A are tumor suppressive
proteins involved in the control of cell invasion which downregulation is associated with metastasis. These proteins were up-regulated by 24-mCAF. Our results suggest that the upregulation of MYBBP1A contributes to stop cancer progression via its interaction with proteins directly involved in cancer related processes, such as p53 and NFκB, and through the inactivation of SIRT6, which leads to the up- or downregulation of TPD52, NDUFB9, FH, MDH1, SEC22B and SEC23A and UGGT1 (Figure 2).
Figure 2. Physiological consequences of MYBBP1A up-regulation by 24-mCAF in A549 cells. Induced cellular functions are shown in orange; repressed cellular functions are shown in blue. Up-regulated proteins are shown in red, down-regulated proteins in green. Colored numbers underneath protein names show iTRAQ ratios; ratios >1 indicate up-regulation, ratios