In Europe, commercially available extracts from the white-berry mistletoe (Viscum album L.) are widely used as a complementary
cancer therapy. Mistletoe
lectins have been identified as main active components and exhibit cytotoxic effects as well as immunomodulatory activity. Since it is still not elucidated in detail how mistle toe extracts such as
ISCADOR communicate their effects, we analyzed the mechanisms that might be responsible for their antitumoral function on a molecular and functional level.
ISCADOR-treated
glioblastoma (GBM) cells down-regulate central genes involved in
glioblastoma progression and
malignancy such as the
cytokine TGF-β and
matrix-metalloproteinases. Using in vitro
glioblastoma/immune cell co-cultivation assays as well as measurement of cell migration and invasion, we could demonstrate that in
glioblastoma cells,
lectin-rich
ISCADOR M and
ISCADOR Q significantly enforce NK-cell-mediated GBM cell lysis. Beside its immune stimulatory effect,
ISCADOR reduces the migratory and invasive potential of
glioblastoma cells. In a syngeneic as well as in a xenograft
glioblastoma mouse model, both pretreatment of
tumor cells and intratumoral
therapy of subcutaneously growing
glioblastoma cells with
ISCADOR Q showed delayed
tumor growth. In conclusion,
ISCADOR Q, showing multiple positive effects in the treatment of
glioblastoma, may be a candidate for concomitant treatment of this
cancer.