Therapeutic Efficacy of Silibinin on Human Neuroblastoma Cells: Akt and NF-κB Expressions May Play an Important Role in Silibinin-Induced Response

Abstract

Neuroblastoma is the most common solid tumor in children. Current therapy modalities have resulted in little amelioration in the cure rate of neuroblsatoma and therefore, outlining biologically based therapies for neuroblastoma remains of main priority. This study was carried out to appraise the impeding effects of silibinin, a potent anti-cancer agent, on two different neuroblastoma cell lines, stromal SK-N-MC and neuroblastic SK-N-BE(2) cells. The microculture tetrazolium assay, gelatin zymography, colony formation assay, cell cycle distribution survey, apoptosis assay, and quantitative real-time reverse transcription-PCR were applied to evaluate the effects of silibinin on metabolic activity, gelatinolytic activity of MMP-2 and MMP-9, surviving potential, cell cycle, apoptosis, and expression pattern of the genes involved in cell survival and invasion of the two neuroblastoma cell lines. Treatment for 48 h inhibited metabolic activity and clonogenic potential of SK-N-MC cells in a dose-dependent manner. Silibinin also inhibited transcriptional levels of MMP-2, MMP-9, and uPAR, as markers of cell invasion, in SK-N-MC cells. Higher concentration of silibinin (75, 100 μM) suppressed enzymatic activity of MMP-2 in this cell line. No change in apoptosis and cell cycle was observed in neither of the cells after treatment with silibinin. On the other hand, silibinin highly decreased mRNA expression of Akt, and NF-κB1 and its regulators, IKK1 and IKK2 in SK-N-MC cell line. Comparison of transcriptional expression of Akt, and NF-κB1 in untreated stromal and neuroblastic cell lines shows that their basal transcriptional levels are much higher in SK-N-BE(2) cell line than that in SK-N-MC cells. It seems that SK-N-BE(2) cell line probably resists to silibinin through higher expression of Akt and probably NF-κB1. Collectively, our results demonstrated that silibinin highly inhibits the proliferative potentials of SK-N-MC cell line, whilst it had less inhibitory effect on SK-N-BE(2) cell line. Our results suggest that suppression of SK-N-MC cell line by silibinin may be through inhibition of Akt-mediated NF-κB1.

Inhibition of SIRT1 Signaling Sensitizes the Antitumor Activity of Silybin against Human Lung Adenocarcinoma Cells In Vitro and In Vivo

“…The anticancer efficacy of silybin is clearly evident in the published reports of its effects against various cancers generated over the last two decades; these effects mainly target proliferation, apoptosis, inflammation, angiogenesis, and cancer cell metabolism (6-10). Various molecules and signaling pathways are involved in the antitumor effects of silybin including VEGF, VEGF receptors, inducible nitric oxide synthase, STAT, PI3K/ Akt, b-catenin, IGF-IGFBP3, NF-kB, and MAPK (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)26). However, the effects of silybin on human lung adenocarcinoma and the mechanisms responsible for these effects are not fully understood.…”

“…1A), a flavanone present in milk thistle (Silybum marianum L.) that is used as a hepatoprotective agent and has been marketed as a dietary supplement (5). Silybin exhibits strong chemopreventive and anticancer properties towards various models of colon (6), liver (7), kidney (8), brain (9), prostate, and breast cancer (10), among others. Moreover, no median lethal dose (lethal dose, 50%; LD 50 ) for silybin has been reported in laboratory animals, and it has also been considered exceptionally safe due to its extremely low toxicity in both animals and humans during acute or chronic administration; these findings emphasize the importance of utilizing this effective biologic agent in cancer chemoprevention studies (1,11).…”

Does silymarin affects neuroblastoma cell death via pro-inflammatory cytokine production with cisplatin?

“…Ayrıca silmarinin özellikle TNF-α'ı azaltarak anti-enflamatuvar etkisinin eritrosit lizisini ve sisplatinin indüklediği akut nefrotoksisiteye karşı koruduğu belirtilmektedir (20) . Bugüne dek nöroblastoma ve silmarin ilişkili sınırlı sayıda çalışma gerçekleştirilmiştir (25)(26)(27) . Silmarinin NB-1 ve IMR-32 insan nöroblastom hüc-relerinde genelde nöronal ve nöroblastom hücrelerin-de baskılanmış bulunan ve viral klirensde etkili olan Major Hitokompatabilite Kompleks Sınıf I'i (MHC) aktive ettiği gösterilmiştir (25) .…”

“…Silmarinin mangana karşı koruyucu etkisinin radikal aracılı hücre ölü-münü düzenleyerek gerçekleştiği belirlenmiştir. Silmarinin major aktif bileşeni olan silibinin metastatik özellikli insan SK-N-MC and SK-N-BE(2) nörob-lastoma hücrelerinde anti-kanser özelliği test edilmiş ve özellikle SK-N-MC hücre hattında Akt aracılı NF-κB1 üzerinden supresyon yaptığı gösterilmiştir (27) . Bugüne dek yapılan çalışmalarda silmarinin tek başına ya da sisplatin kombinasyonu ile proinflamatuvar proteinler üzerindeki etkisi incelenmemiştir.…”

“…Bu çalışmada, fare kökenli C1300 nöroblastom hücrelerinde doz bağımlı olarak hücre canlılığını azaltarak apoptotik hücre ölümüne neden olduğu daha önce yapılan bir çalışma ile uyumlu olarak belirlenmiştir (27) . Yine silmarinin nöroblastom tedavisinde kullanılan ana tedavi ajanı olan sisplatin ile benzer düzeyde hücre canlılığını azalttığı gibi aynı zamanda hücreleri apoptotik hücre ölümüne sürükle-miştir.…”