RESUMO
BACKGROUND: Sulforaphane (SFN), a natural compound present in cruciferous vegetable, has been shown to possess anti-cancer activities. Cancer stem cell (CSC) in bulk tumor is generally considered as treatment resistant cell and involved in cancer recurrence. The effects of SFN on nasopharyngeal carcinoma (NPC) CSCs have not yet been explored. PURPOSE: The present study aims to examine the anti-tumor activities of SFN on NPC cells with CSC-like properties and the underlying mechanisms. METHODS: NPC cells growing in monolayer culture, CSCs-enriched NPC tumor spheres, and also the NPC nude mice xenograft were used to study the anti-tumor activities of SFN on NPC. The population of cells expressing CSC-associated markers was evaluated using flow cytometry and aldehyde dehydrogenase (ALDH) activity assay. The effect of DNA methyltransferase 1 (DNMT1) on the growth of NPC cells was analyzed by using small interfering RNA (siRNA)-mediated silencing method. RESULTS: SFN was found to inhibit the formation of CSC-enriched NPC tumor spheres and reduce the population of cells with CSC-associated properties (SRY (Sex determining Region Y)-box 2 (SOX2) and ALDH). In the functional study, SFN was found to restore the expression of Wnt inhibitory factor 1 (WIF1) and the effect was accompanied with the downregulation of DNMT1. The functional activities of WIF1 and DNMT1 were confirmed using exogenously added recombinant WIF1 and siRNA knockdown of DNMT1. Moreover, SFN was found to inhibit the in vivo growth of C666-1 cells and enhance the anti-tumor effects of cisplatin. CONCLUSION: Taken together, we demonstrated that SFN could suppress the growth of NPC cells via the DNMT1/WIF1 axis.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Antineoplásicos Fitogênicos/farmacologia , DNA (Citosina-5-)-Metiltransferase 1/metabolismo , Isotiocianatos/farmacologia , Carcinoma Nasofaríngeo/tratamento farmacológico , Neoplasias Nasofaríngeas/tratamento farmacológico , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Antineoplásicos Fitogênicos/administração & dosagem , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Brassicaceae/química , Linhagem Celular Tumoral , Cisplatino/administração & dosagem , DNA (Citosina-5-)-Metiltransferase 1/genética , Humanos , Isotiocianatos/administração & dosagem , Masculino , Camundongos Endogâmicos BALB C , Camundongos Nus , Carcinoma Nasofaríngeo/metabolismo , Carcinoma Nasofaríngeo/patologia , Neoplasias Nasofaríngeas/metabolismo , Neoplasias Nasofaríngeas/patologia , Células-Tronco Neoplásicas/efeitos dos fármacos , Células-Tronco Neoplásicas/patologia , Fatores de Transcrição SOXB1/genética , Fatores de Transcrição SOXB1/metabolismo , Sulfóxidos , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
MicroRNAs (miRNAs) are small non-coding RNAs that act as post-transcriptional gene modulators. Ginsenoside-Rg1, one of the active components of ginseng, has been confirmed as an angiogenesis inducer. Using miRNA microarray analysis, a total of 17 (including miR-214) and 5 miRNAs were found to be down- or up-regulated by Rg1 in human umbilical vein endothelial cells (HUVECs), respectively. Since miR-214 is closely related to endothelial nitric oxide synthase (eNOS) and hence angiogenesis, its expression was further validated by qRT-PCR. We also investigated the role of miR-214 on eNOS expression and in tubulogenesis and motility of HUVEC by transfection of specific miRNA inhibitor or precursor. Our results suggested that Rg1 can down-regulate miR-214 expression in HUVEC, leading to an increase in eNOS expression, and in vitro cell migration and tube formation which can possibly promote angiogenesis. These results signify a new understanding towards how a simple natural compound can affect physiological changes through modulation of miRNA expression.