Abstract

Melanoma is the more dangerous skin cancer, and metastatic melanoma still carries poor prognosis. Despite recent therapeutic advances, prolonged survival remains rare and research is still required. Propolis extracts from many countries have attracted a great deal of attention for their biological properties. We here investigated the ability of an ethanolic extract of Algerian propolis (EEP) to control melanoma tumour growth when given to mice bearing B16F1melanoma tumour either as preventive or as therapeutic treatment. EEP given after tumour occurrence increased mice survival (+30%) and reduced tumour growth (-75%). This was associated with a decrease of the Mitotic Index (-75%) and of Ki-67 (-50%) expression. When given either before or both before and after tumour occurrence, EEP reduced tumour growth but without prolonging mice life. Isolation of B16F1 melanoma cells from resected tumour showed that preventive and curative EEP treatments reduced invasiveness by 55% and 40% respectively compared to control. Galangin, one of the most abundant flavonoids in propolis, significantly reduced the number of melanoma cells in vitro and induced autophagy/apoptosis dose dependently. In conclusion, we showed that EEP reduced melanoma tumour progression/dissemination and could extend mice lifespan when used as therapeutic treatment. Then, EEP may help patients with melanoma when used as a complementary therapy to classical treatment for which autophagy is not contraindicated.

Keywords: Melanoma, propolis, complementary medicine, galangin, dermatology.

Graphical Abstract