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Open Access Research article

Propolis changes the anticancer activity of temozolomide in U87MG human glioblastoma cell line

Renata Markiewicz-Żukowska1, Maria H Borawska1*, Anna Fiedorowicz2, Sylwia K Naliwajko1, Diana Sawicka3 and Halina Car2

Author Affiliations

1 The Department of Bromatology, Medical University of Bialystok, Mickiewicza 2D, 15-222, Bialystok, Poland

2 The Department of Experimental Pharmacology, Medical University of Bialystok, Szpitalna 37, 15-295, Bialystok, Poland

3 The Center of Experimental Medicine, Medical University of Bialystok, Marii Sklodowskiej-Curie 24A, 15-276, Bialystok, Poland

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BMC Complementary and Alternative Medicine 2013, 13:50  doi:10.1186/1472-6882-13-50

Published: 27 February 2013

Abstract

Background

Propolis 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.

Methods

The 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.

Results

We 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.

Conclusions

We 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.

Keywords:
Propolis; Glioblastoma; Temozolomide; Cell viability; DNA synthesis; NF-κB