An Investigation into the potential anti-cancer activities of an extract from a Himalayan fungus

Abstract

Medicinal mushrooms have been used for the treatment of diseases and general promotion of health for many centuries. Recent pharmacological research into medicinal mushrooms has identified various therapeutic properties, with applications in modern medicine. In this study, we were supplied with novel alcoholic extracts of a Himalayan bracket fungus identified as Ganoderma lucidum. Our aims were to identify if the extracts had anti-cancer activities, their associated biological pathways, and the identification of bioactive fractions/components. We used a combination of in vitro and in vivo studies to examine the anti-cancer effects of the bracket fungal extracts. In addition, we investigated the impact of the extracts on gene and protein expression using Affymetrix microarray, real-time PCR, and Western blot. We identified several biologically active pathways associated with the extract such as cell cycle inhibition (Bayes factors >15) and activation of apoptosis (Bayes factors >9). In the in vitro experiments, we found statistically significant growth inhibition in response to treatment with the extracts in prostate (IC50 = 1.33 μl), breast (IC50 = 1.65 μl), colorectal (IC50 = 1.36 μl), and skin cancer cell lines (IC50 = 1.85 μl). In addition, activation of apoptosis was observed in prostate cancer cell lines, but not in the non-cancerous control cell line. Comparative effects were not observed in in vivo xenograft studies using immunecompromised mice. Metabolomics and pharmacokinetic studies were utilised to understand this phenomenon. We deduced that the problem was associated with bioavailability as administration of the extract via oral gavage did not deliver the bioactive components to mouse plasma or the tumour site. This is likely due to the timing of treatment, dosage levels and modifications made to the extract which replaced the alcoholic-based with a water-based solvent. This, in combination with fractionation studies which identified most anti-cancer compounds to be hydrophobic, largely explained the lack of anti-cancer activities in vivo. Lastly, sequencing and matching of ITS2 (Internal transcribed spacer 2) sequences were used to identify the mushroom species used in the extract. We have assessed the potential anti-cancer activities of the bracket fungal extracts using a combination of next-generation –omics technologies and well-established robust techniques across multiple disciplines.