Immune - modulatory effects of sidr honey: implications for anti-proliferative effects on cancer cells

Abstract

Honey has become popular as a potential treatment for several ailments, including many cancers. Being a natural product, honey is often considered to be a safe and inexpensive adjunct or sometimes even an alternative to the currently available cancer treatments (including chemotherapy and radiotherapy) that have adverse side effects. Honeys from different parts of the world have shown anti-proliferative, immune-modulatory, and anti-inflammatory actions. Yemeni Sidr Honey (YSH) is a world-renowned honey whose anti-inflammatory activity suggests the possibility of underlying anti-cancer and/or immune-modulatory actions. Our studies have shown that treatment with 1% YSH is able to inhibit proliferation, and induce apoptosis in breast cancer cell lines (MDA-MB-231 and MCF-7) and cervical cancer cell lines (Hela). We also showed that THP-1 monocyte-like cells differentiated by treatment with phorbol ester and then treated with YSH affected their polarization into M1 or M2 macrophages: treatment with YSH for 24 h, enhanced the expression of the M1 phenotype while treatment of the macrophages with LPS and YSH for 48 h increased the level of M2 markers of differentiation. Further, co-culture of the M1 differentiated macrophages with breast cancer cells showed that treatment of the macrophages with YSH decreased tumour cell growth and increased apoptosis. These results suggest treatment with YSH is able to impact cancer via two separate mechanisms: direct impacts on cancer cell survival and activation of anti-tumour immune system (monocyte) activation.