Abstract
BackgroundPropolis is a honey bee product which contains many active compounds, such as CAPE or chrysin, and has many beneficial activities. Recently, its anti-tumor properties have been discussed. We have tested whether the ethanolic extract of propolis (EEP) interferes with temozolomide (TMZ) to inhibit U87MG cell line growth.MethodsThe U87MG glioblastoma cell line was exposed to TMZ (10-100 μM), EEP (10-100 μg/ml) or a mixture of TMZ and EEP during 24, 48 or 72 hours. The cell division was examined by the H3-thymidine incorporation, while the western blot method was used for detection of p65 subunit of NF-κB and ELISA test to measure the concentration of its p50 subunit in the nucleus.ResultsWe have found that both, TMZ and EEP administrated alone, had a dose- and time-dependent inhibitory effect on the U87MG cell line growth, which was manifested by gradual reduction of cell viability and alterations in proliferation rate. The anti-tumor effect of TMZ (20 μM) was enhanced by EEP, which was especially well observed after a short time of exposition, where simultaneous usage of TMZ and EEP resulted in a higher degree of growth inhibition than each biological factor used separately. In addition, cells treated with TMZ presented no changes in NF-κB activity in prolonged time of treatment and EEP only slightly reduced the nuclear translocation of this transcription factor. In turn, the combined incubation with TMZ and EEP led to an approximately double reduction of NF-κB nuclear localization.ConclusionsWe conclude that EEP presents cytotoxic properties and may cooperate with TMZ synergistically enhancing its growth inhibiting activity against glioblastoma U87MG cell line. This phenomenon may be at least partially mediated by a reduced activity of NF-κB.
Highlights
Propolis is a honey bee product which contains many active compounds, such as Caffeic acid phenethyl ester (CAPE) or chrysin, and has many beneficial activities
The effects of ethanolic extract of propolis (EEP) and EEP with TMZ on the viability of glioblastoma cell line (U87MG) Basing on the comparative analysis of the effects of different TMZ concentrations on Glioblastoma cell line (U87MG) cell growth, we established that 20 μM of TMZ is the most appropriate concentration which should be used in further experiments (Figure 1)
In this work we have presented the cooperative effect of temozolomide and ethanolic extract of propolis on the growth of glioblastoma U87MG cell line
Summary
Propolis is a honey bee product which contains many active compounds, such as CAPE or chrysin, and has many beneficial activities. We have tested whether the ethanolic extract of propolis (EEP) interferes with temozolomide (TMZ) to inhibit U87MG cell line growth. Glioblastoma is a common primary brain tumor which demonstrates a high proliferation rate and an aggressive growth pattern and is largely resistant to chemotherapy [1]. One of the most promising drugs for brain tumor therapy is temozolomide (TMZ) (8-carbamoyl-3methylimidazo [5,1-d]- 1,2,3,5-tetrazin-4 (3H)-one), an oral alkylating agent belonging to imidazotertrazines [2], which exhibits anti-cancer properties against malignancies [1,3,4]. A natural honeybee product, propolis has been demonstrated in many studies due to its antibacterial, antifungal [8,9,10], antiviral [11] hepatoprotective and immunostimulative activities [12]. It has been showed that the efficacy of propolis depends on the contents of the mentioned ingredients in particular flavonoids [13,14]
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