Papers by Yon Rojanasakul
Environmental science & technology, Jan 24, 2015
The clinical applications of digitoxin as a cardiac glycoside have been halted by many concerns a... more The clinical applications of digitoxin as a cardiac glycoside have been halted by many concerns associated with its cardiac toxicity. Recently it was shown that the toxic profiles induced by therapeutic ranges of digitoxin exposure are selective to many types of neoplastic cells from breast to prostate and lung cancer, making this drug an attractive candidate for chemotherapies. The anticancer potency of digitoxin lays in its trisaccharide moiety linked to a steroid core. Further research has shown that synthetic manipulation of digitoxin structure leads to more potent analogues. In this research, a new approach is used to characterize and quantify the cellular behavior of immortalized and tumorigenic human lung cells (BEAS-2B and H460 respectively) upon exposure to different concentrations of digitoxin and synthetic monosaccharide analogue (D6-MA) in real time. The approach relies on an electrical cell impedance sensing system (ECIS) used as a proxy to measure the morphological cha...
Digitoxin is a naturally occurring cardiac glycoside, well known for its efficiency in the treatm... more Digitoxin is a naturally occurring cardiac glycoside, well known for its efficiency in the treatment of congestive heart failure and arrhythmias. Recently, several reports have shown that digitoxin exhibits anti-neoplastic effects against several types of cancer ranging from breast to colon cancer, and from leukemia to lung cancer, suggesting digitoxin’s potential as a chemotherapeutic agent. The anticancer potency of digitoxin lies in its trisaccharide moiety which could be synthetically manipulated to produce a library of analogues. In our research we used an electrical cell impedance sensing system (ECIS) as a proxy to assess the cellular behavior of immortalized and tumorigenic human lung cells (BEAS-2B and H460 respectively) upon exposure to digitoxin and a synthetic monosaccharide (D6-MA). Our highthroughput, non-invasive approach employed arrays with gold electrodes as immobilization platforms to measure the changes in cellular attachment, migration and cell-cell interactions...
Journal of materials chemistry. B, Materials for biology and medicine
The toxicity of engineered nanomaterials in biological systems depends on both the nanomaterial p... more The toxicity of engineered nanomaterials in biological systems depends on both the nanomaterial properties and the exposure duration. Herein we used a multi-tier strategy to investigate the relationship between user-characterized multi-walled carbon nanotubes (MWCNTs) exposure duration and their induced biochemical and biomechanical effects on model human lung epithelial cells (BEAS-2B). Our results showed that exposure to MWCNTs leads to time-dependent intracellular uptake and generation of reactive oxygen species (ROS), along with time-dependent gradual changes in cellular biomechanical properties. In particular, the amount of internalized MWCNTs followed a sigmoidal curve with the majority of the MWCNTs being internalized within 6h of exposure; further, the sigmoidal uptake correlated with the changes in the oxidative levels and cellular biomechanical properties respectively. Our study provides new insights into the time-dependent induced toxicity caused by exposure to occupation...
Journal of functional foods, 2015
Galangin and myricetin are flavonoids isolated from vegetables and fruits which exhibit anti-prol... more Galangin and myricetin are flavonoids isolated from vegetables and fruits which exhibit anti-proliferative activity in human cancer cells. In this study, their anti-angiogenic effects were investigated with in vitro (HUVEC) and in vivo (CAM) models, which showed that galangin and myricetin inhibited angiogenesis induced by OVCAR-3 cells. The molecular mechanisms through which galangin and myricetin suppress angiogenesis were also studied. It was observed that galangin and myricetin inhibited secretion of the key angiogenesis mediator vascular endothelial growth factor (VEGF) and decreased levels of p-Akt, p-70S6K and hypoxia-inducible factor-1α (HIF-1α) proteins in A2780/CP70 and OVCAR-3 cells. Transient transfection experiments showed that galangin and myricetin inhibited secretion of VEGF by the Akt/p70S6K/ HIF-1α pathway. Moreover, a novel pathway, p21/HIF-1α/VEGF, was found to be involved in the inhibitory effect of myricetin on angiogenesis in OVCAR-3 cells. These data suggest ...
Journal of Cellular Physiology, 2003
Induction of apoptosis has been associated with a variety of exposures which result in inflammato... more Induction of apoptosis has been associated with a variety of exposures which result in inflammatory and fibrotic lung disorders. Macrophages are key regulatory cells in the lung; however, the role of apoptotic macrophages in those pulmonary disorders is not well characterized. In the present investigation, apoptotic macrophages were instilled into the lungs of rats to study directly the pulmonary responses to apoptotic cells. The effects of apoptotic macrophages on lung inflammation and fibrosis, as well as associated protein expression of TNF-alpha, TGF-beta, and matrix metalloproteinases (MMPs) were examined. Induction of macrophage apoptosis was carried out in vitro using a variety of known apoptosis inducers. Intratracheal administration of apoptotic macrophages (5 x 10(6) cells/rat) into the lung of rats caused an increase in pulmonary infiltration of macrophages and lung cell apoptosis 4 weeks after the treatment as indicated by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay. In contrast, pulmonary instillation of saline or normal control macrophages had no effect. Histological analysis of lung sections showed collagen deposition and fibrotic lesions after apoptotic cell treatment but not in control groups. Immunohistochemical studies revealed increased expression of TNF-alpha, TGF-beta, MMP2, and MMP9 in the treatment group 4 weeks after the treatment. These results suggest a role for macrophage apoptosis in the initiation of these lung disorders. This study provides direct evidence that apoptotic macrophages can induce lung inflammation and fibrosis and that this induction may be associated with increased expression of TNF-alpha, TGF-beta, MMP2, and MMP9. Published 2002 Wiley-Liss, Inc.
Carcinogenesis, 2015
Lifestyle factors are responsible for a considerable portion of cancer incidence worldwide, but c... more Lifestyle factors are responsible for a considerable portion of cancer incidence worldwide, but credible estimates from the World Health Organization and the International Agency for Research on Cancer (IARC) suggest that the fraction of cancers attributable to toxic environmental exposures is between 7% and 19%. To explore the hypothesis that low-dose exposures to mixtures of chemicals in the environment may be combining to contribute to environmental carcinogenesis, we reviewed 11 hallmark phenotypes of cancer, multiple priority target sites for disruption in each area and prototypical chemical disruptors for all targets, this included dose-response characterizations, evidence of low-dose effects and cross-hallmark effects for all targets and chemicals. In total, 85 examples of chemicals were reviewed for actions on key pathways/mechanisms related to carcinogenesis. Only 15% (13/85) were found to have evidence of a dose-response threshold, whereas 59% (50/85) exerted low-dose effe...
Carcinogenesis, 2015
Cell death is a process of dying within biological cells that are ceasing to function. This proce... more Cell death is a process of dying within biological cells that are ceasing to function. This process is essential in regulating organism development, tissue homeostasis, and to eliminate cells in the body that are irreparably damaged. In general, dysfunction in normal cellular death is tightly linked to cancer progression. Specifically, the up-regulation of pro-survival factors, including oncogenic factors and antiapoptotic signaling pathways, and the down-regulation of pro-apoptotic factors, including tumor suppressive factors, confers resistance to cell death in tumor cells, which supports the emergence of a fully immortalized cellular phenotype. This review considers the potential relevance of ubiquitous environmental chemical exposures that have been shown to disrupt key pathways and mechanisms associated with this sort of dysfunction. Specifically, bisphenol A, chlorothalonil, dibutyl phthalate, dichlorvos, lindane, linuron, methoxychlor and oxyfluorfen are discussed as prototyp...
Oncotarget, Jan 7, 2015
AF1q is an MLL fusion partner that was identified from acute myeloid leukemia (AML) patients with... more AF1q is an MLL fusion partner that was identified from acute myeloid leukemia (AML) patients with t (1; 11) (q21; q23) chromosomal abnormality. The function of AF1q is not yet fully known, however, elevated AF1q expression is associated with poor clinical outcomes in various malignancies. Here, we show that AF1q specifically binds to T-cell-factor-7 (TCF7) in the Wnt signaling pathway and results in transcriptional activation of CD44 as well as multiple downstream targets of the TCF7/LEF1. In addition, enhanced AF1q expression promotes breast cancer cell proliferation, migration, mammosphere formation, and chemo-resistance. In xenograft models, enforced AF1q expression in breast cancer cells also promotes liver metastasis and lung colonization. In a cohort of 63 breast cancer patients, higher percentages of AF1q-positive cancer cells in primary sites were associated with significantly poorer overall survival (OS), disease-free survival (DFS), and brain metastasis-free survival (b-MF...
International journal of oncology, 2015
Despite its importance, the death rate of ovarian cancer has remained unchanged over the past fiv... more Despite its importance, the death rate of ovarian cancer has remained unchanged over the past five decades, demanding an improvement in prevention and treatment of this malignancy. With no known carcinogens, targeted prevention is currently unavailable, and efforts in early detection of this malignancy by screening biomarkers have failed. The inhibition of angiogenesis, also known as angioprevention, is a promising strategy to limit the growth of solid tumors, including ovarian cancers. Nobiletin, a polymethoxy flavonoid compound isolated from the tiansheng plant, has been shown to inhibit the growth of multiple types of human cancers. However, there are no reports involving the effect on nobiletin on human ovarian cancer. The present report shows that nobiletin potently decreases the viability of ovarian cancer cells in vitro. However, nobiletin does not affect the viability of normal ovarian epithelial cells at <40 µM. The antitumor activity of nobiletin was also observed in at...
Molecular and cellular biochemistry, 2000
Electron spin resonance (ESR) spin trapping was utilized to investigate the scavenging effects on... more Electron spin resonance (ESR) spin trapping was utilized to investigate the scavenging effects on hydroxyl radicals (*OH) and superoxide radicals (O2*-) by (-)-epigallocatechin-3-gallate (EGCG), one of the major anticancer compounds in tea. The spin trap used was 5,5-dimethyl-pyrroline N-oxide (DMPO). The Fenton reaction (Fe2+ + H2O2-->Fe3+ + *OH + OH-) was used as a source of *OH radicals. EGCG efficiently scavenges *OH radicals with reaction rate of 4.62 x 10(11) M(-1)sec(-1), which is an order of magnitude higher than several well recognized antioxidants, such as ascorbate, glutathione and cysteine. It also scavenges O2*- radicals as demonstrated by using xanthine and xanthine oxidase system as a source of O2*- radicals. Through its antioxidant properties, EGCG exhibited a protective effect against DNA damage induced by Cr(VI). EGCG also inhibited activation of nuclear transcription factor NF-kappaB induced by Cr(IV) and 12-o-tetradecanoylphorbol-13-acetate (TPA). The present ...
Despite the intriguing potential of carbon nanotubes (CNTs) for biomedical applications, their im... more Despite the intriguing potential of carbon nanotubes (CNTs) for biomedical applications, their implementation is currently being hindered by many uncertainties regarding their toxicity and fate inside the biological systems. Several reports have shown that CNTs toxicity can be attributed to their length, surface chemistry, aggregation and metal impurities, just to name a few. However, due to the various types of CNTs being synthesized every day along with the different surface functionalization techniques, there is no fundamental understanding of the toxicological and pharmacological profiles of cellular systems exposed to CNTs with different physico-chemical properties. In this research, we provide a comprehensive analysis of the cellular behavior of human lung cells post exposure to CNTs using a combination of electronic and cell-based techniques. Our analyses rely on a non-invasive electronic cell impedance sensing (ECIS) platform to provide real-time measurements of cell adhesio...
American Journal of Physiology - Cell Physiology, 2014
Even though tremendous advances have been made in the treatment of cancers during 25 the past dec... more Even though tremendous advances have been made in the treatment of cancers during 25 the past decades, success rate among cancer patients is still dismal largely due to problems 26 associated with chemo/radio-resistance and relapse. Emerging evidence has indicated that 27 cancer stem cells (CSCs) are behind the resistance and recurrence problems, but our 28 understanding of their regulation is limited. Rapid reversible changes of CSC-like cells 29 within tumors may result from the effect of biological mediators found in tumor 30 microenvironment. Here we show how nitric oxide (NO), a key cellular modulator whose 31 level is elevated in many tumors, affects CSC-like phenotypes of human non-small-cell lung 32 carcinoma (NSCLC) H292 and H460 cells. Exposure of NO gradually altered the cell 33 morphology towards mesenchymal stem-like shape. NO exposure promoted CSC-like 34 phenotype indicated by increased expression of known CSC markers, CD133 and 35 ALDH1A1, in the exposed cells. These effects of NO on stemness was reversible after 36 cessation of the NO treatment for 7 days. Furthermore, such effect was reproducible using 37 another NO-donor, S-nitroso-N-acetylpenicillamine (SNAP). Importantly, inhibition of NO 38 by known NO scavenger 2-(4-carboxy-phenyl)-4,4,5,5 tetramethylimidazoline-1-oxy-3-oxide 39 (PTIO) strongly inhibited CSC-like aggressive cellular behavior and marker expression.
Nanoscale Research Letters, 2015
A rapid increase in utility of engineered nanomaterials, including carbon nanotubes (CNTs), has r... more A rapid increase in utility of engineered nanomaterials, including carbon nanotubes (CNTs), has raised a concern over their safety. Based on recent evidence from animal studies, pulmonary exposure of CNTs may lead to nanoparticle accumulation in the deep lung without effective clearance which could interact with local lung cells for a long period of time. Physicochemical similarities of CNTs to asbestos fibers may contribute to their asbestos-like carcinogenic potential after long-term exposure, which has not been well addressed. More studies are needed to identify and predict the carcinogenic potential and mechanisms for promoting their safe use. Our previous study reported a long-term in vitro exposure model for CNT carcinogenicity and showed that 6-month sub-chronic exposure of single-walled carbon nanotubes (SWCNT) causes malignant transformation of human lung epithelial cells. In addition, the transformed cells induced tumor formation in mice and exhibited an apoptosis resistant phenotype, a key characteristic of cancer cells. Although the potential role of p53 in the transformation process was identified, the underlying mechanisms of oncogenesis remain largely undefined. Here, we further examined the gene expression profile by using genome microarrays to profile molecular mechanisms of SWCNT oncogenesis. Based on differentially expressed genes, possible mechanisms of SWCNT-associated apoptosis resistance and oncogenesis were identified, which included activation of pAkt/p53/Bcl-2 signaling axis, increased gene expression of Ras family for cell cycle control, Dsh-mediated Notch 1, and downregulation of apoptotic genes BAX and Noxa. Activated immune responses were among the major changes of biological function. Our findings shed light on potential molecular mechanisms and signaling pathways involved in SWCNT oncogenic potential.
Oncology Letters, 2014
Ovarian cancer is a disease that continues to cause mortality in female individuals worldwide. Ov... more Ovarian cancer is a disease that continues to cause mortality in female individuals worldwide. Ovarian cancer is challenging to treat due to emerging resistance to chemotherapy, therefore, the identification of effective novel chemotherapeutic agents is important. Polyphenols have demonstrated potential in reducing the risk of developing numerous types of cancer, as well reducing the risk of cancer progression, due to their ability to reduce cell viability and vascular endothelial growth factor (VEGF) expression. In the present study, eight phenolic compounds were screened in two human ovarian cancer cell lines (OVCAR-3 and A2780/CP70) to determine their effect on proliferation suppression and VEGF protein secretion inhibition, in comparison to cisplatin, a conventional chemotherapeutic agent. The current study identified that 40 µM gallic acid (GA) exhibited the greatest inhibitory effect on OVCAR-3 cell viability, compared with all of the phenolic compounds investigated. Similarly to cisplatin, baicalein, GA, nobiletin, tangeretin and baicalin were all identified to exhibit significant VEGF inhibitory effects from ELISA results. Furthermore, western blot analysis indicated that GA effectively decreased the level of the VEGF-binding protein hypoxia-inducible factor-1α in the ovarian cancer cell line. Considering the results of the present study, GA appears to inhibit cell proliferation and, thus, is a potential agent for the treatment of ovarian cancer.
Environ. Sci.: Nano, 2014
Toxicity of engineered nanomaterials is associated with their inherent properties, both physical ... more Toxicity of engineered nanomaterials is associated with their inherent properties, both physical and chemical. Recent studies have shown that exposure to multi-walled carbon nanotubes (MWCNTs) promotes tumors and tumor-associated pathologies and lead to carcinogenesis in model in vivo systems. Here in we examined the potential of purified MWCNTs used at occupationally relevant exposure doses for particles not otherwise regulated to affect human lung epithelial cells. The uptake of the purified MWCNTs was evaluated using fluorescence activated cell sorting (FACS), while the effects on cell fate were assessed using 2- (4-iodophenyl) - 3- (4-nitrophenyl) - 5-(2, 4-disulfophenyl) -2H-tetrazolium salt colorimetric assay, cell cycle and nanoindentation. Our results showed that exposure to MWCNTs reduced cell metabolic activity and induced cell cycle arrest. Our analysis further emphasized that MWCNTs-induced cellular fate results from multiple types of interactions that could be analyzed by means of intracellular biomechanical changes and are pivotal in understanding the underlying MWCNTs-induced cell transformation.
The goal of this study was to investigate the feasibility of utilizing epidermal growth factor (E... more The goal of this study was to investigate the feasibility of utilizing epidermal growth factor (EGF) receptor-mediated endocytosis to enhance cellular uptake and targeting of oligonucleotides in epithelial cancer cells. To overcome the problem of endosomal entrappment associated with receptor-mediated delivery, we also examined the effects of two fusogenic peptides, polymyxin B and influenza HA2 peptide, for their capability to promote cytoplasmic delivery of oligonucleotides. A molecular conjugate consisting of EGF and poly-L-lysine (PL) was synthesized and complexed with 5&#39; fluorescently-labeled oligonucleotide. Cellular uptake of the complex in presence or absence of the fusogenic peptides was monitored fluorometrically. Microscopic studies were performed to visualize the intracellular distribution of the oligonucleotide. Cells treated with the complex exhibited intracellular fluorescence intensity significantly enhanced over free oligonucleotide-treated controls. The uptake of the complex was shown to occur via the EGF receptor-mediated pathway. Fluorescence microscopic studies revealed cellular internalization of the complex, however, the complex appeared to be accumulated in endocytic vesicles. Exposure of the cells to complex in presence of HA2 peptide and polymyxin B resulted in a more diffused intracellular fluorescence pattern and a corresponding increase in fluorescence intensity. These results are consistent with the known fusion and destabilizing activities of the peptides. Since EGF receptors are overexpressed in many cancer cell types, the EGF-PL conjugate may potentially be used as an effective and selective delivery system to enhance uptake of oligonucleotides into cancer cells.
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Papers by Yon Rojanasakul