Antitumoral Effect of Hibiscus sabdariffa on Human Squamous Cell Carcinoma and Multiple Myeloma Cells.

Cancer is a leading cause of death worldwide. Despite therapeutic improvements, some cancers are still untreatable. Recently there has been an increasing interest in the use of natural substances for cancer prevention and treatment. Hibiscus sabdariffa (HS) is a plant, belonging to Malvaceae family, widespread in South Asia and Central Africa. HS extract (HSE) used in folk medicine, gained researchers' interest thanks to its antioxidant, anti-inflammatory, and chemopreventive properties. In the present study, we initially assessed HSE effect on a panel of human tumor cell lines. Then we focused our study on the following that are most sensitive to HSE action cell lines: Multiple Myeloma (MM) cells (RPMI 8226) and Oral Squamous Cell Carcinoma (OSCC) cells (SCC-25). In both RPMI 8226 and SCC-25 cells, HSE impaired cell growth, exerted a reversible cytostatic effect, and reduced cell motility and invasiveness. We evaluated the involvement of MAPKs ERK1/2 and p38 in HSE effects by using specific inhibitors, U0126 and SB203580, respectively. For both SCC-25 and RPMI 8226, HSE cytostatic effect depends on p38 activation, whereas ERK1/2 modulation is crucial for cell motility and invasiveness. Our results suggest that HSE may be a potential therapeutic agent against MM and OSCC.