Examination of immunomodulatory and cytotoxic effects of aqueous exstract of white mistletoe (Viscum album L.) in vitro and in patients treated with anthracycline chemotherapeutics

Abstract

Uspešnost antitumorske terapije je ograničena pojavom tumorske rezistencije na lekove putem molekularnih mehanizama koji i dalje ostaju nerazjašnjeni. Kako bi se smanjili neželjeni efekti i poboljšala efikasnost standardnih hemioterapija i radioterapija, počeli su da se primenjuju mnogi komplementarni ili alternativni medikamenti. Bela imela (lat. Viscum album L) se tradicionalno koristi u lečenju pojedinih vrsta tumora. Terapijska korist od primene bele imele kada se koristi zajedno sa hemioterapijom ili radioterapijom, odnosno operacijom doprinosi ukupnom poboljšanju kvaliteta života kod pacijenata obolelih od tumora. Dosadašnja istraživanja na ćelijama u kulturi i na životinjskim modelima, su pokazala da potencijalni mehanizmi delovanja sastojaka bele imele uključuju antitumorsko, antiinflamatorno i imunomodulatorno dejstvo. Uprkos intezivnim ispitivanjima, mehanizam antitumorskog dejstva ekstrakta bele imele je još uvek u velikom obimu nepoznat. Takođe, malo je i naučnih podataka o mehanizmu interakcije bioaktivnih komponenti bele imele i drugih antitumorskih citotoksičnih lekova, koji bi pružili zasnovanost daljem kliničkom ispitivanju. Cilj ove disertacije je utvrđivanje imunomodulatornog dejstva ekstrakta bele imele na ćelije imunskog sistema u in vitro i in vivo uslovima, ispitivanje citotoksičnog efekta ekstrakta bele imele in vitro i molekularnih mehanizma interakcije bioaktivnih komponenti ekstrakta bele imele sa citotoksičnim agensom iz grupe antraciklina na modelu tumorskih ćelija u kulturi. Rezultati dobijeni u in vitro istraživanjima su pokazali citotoksični i antiproliferativni efekat ekstrakta bele imele, putem indukcije apoptoze tumorskih ćelija unutrašnjim mitohondrijskim putem i indukcijom zastoja u G0/G1 fazi ćelijskog ciklusa. Kombinovani tretman tumorskih ćelija subterapeutskom koncentracijom doksorubicina i ekstraktom bele imele dovodi do sinergističkog inhibitornog efekta...Success of anticancer treatment has been impeded by resistance to anti-tumor therapy via molecular mechanisms that still remain elusive. To reduce side effects and improve the effectiveness of standard chemoradiation therapy, many complementary or alternative medicines (CAM) have been investigated. Mistletoe (Viscum album L) has been long used as CAM supporting cancer therapy. Therapeutic benefit of mistletoe preparations when utilized along with surgery, chemotherapy or radiotherapy contributes to the overall improvement in the quality of life in cancer patients. Several lines of evidence have revealed that mistletoe preparations in vitro and in vivo exert an anti-cancer, anti-inflamatory and immunomodulatory effects. Despite extensive experimental analyses of their biological properties, many questions regarding the precise mode of action of mistletoe still remain elusive. Also, there is only little information about interactions between mistletoe and anticancer drugs, which would provide validity for further clinical investigations. The aims of this study are investigation of immunomodulatory effects of mistletoe extracts on immune cells in vitro and in vivo, examination of cytotoxic effect in vitro, as well as molecular mechanisms underlying interactions between mistletoe and anticancer drug from the antraciklenes family on the tumor cells in culture. Our results from in vivo study study have shown cytotoxic and antiproliferative effect of mistletoe extract via induction of apoptosis of cancer cells through intrinsic mitochondrial pathway and induction of G0/G1 arrest. Also, combined treatment of cancer cells with sub-therapeutic concentration of doxorubicine and mistletoe extract led to synergistic inhibitory effect. Increased K562 and MCF7 cells apoptotic death during cotreatment was associated with reduced G2/M accumulation during doxorubicine treatment..