B-glucans from Grifola frondosa and Ganoderma lucidum in breast cancer: an example of complementary and integrative medicine

Abstract

Culinary and medicinal mushrooms are widely used in Asian countries, both as dietary supplements and as nutraceutical foods. They have recently become popular in Europe, as well, for their nutritional and health benefits. In particular, epidemiological studies conducted in Asia suggest that mushroom intake, together with other phytotherapy substances, protects against cancer, specifically gastrointestinal (GI) and breast cancers. Most of the data come from in vitro studies and in vivo experimental animal models. Therefore, in order to translate the updated knowledge to clinical research (i.e., from bench to bedside) a systematic translational research program should be initiated. Future randomized controlled trials comparing the effects of G. frondosa and G. lucidum on conventional treatment outcomes are warranted. The purpose of this review was to describe the emerging mechanisms of action of the mushrooms' anticancer functions which makes their use in clinical practice so promising. Clinical effects of mycotherapy (specifically, the use of Ganoderma lucidum and Grifola frondosa) on long-term survival, tumor response, host immune functions, inflammation, and QoL in cancer patients were also addressed. Adverse events associated with mycotherapy were also investigated. Emerging data point to a potential role of G. lucidum for modulating the carcinogenic potential of GI microbiota, which suggests a new complementary and integrated approach to breast cancer treatment.

Keywords: G. frondosa; G. lucidum; breast cancer; immunomodulation; microbiota.

Figure 1. The polymeric structure of β-glucans

These molecules are constituted by heterogeneous groups of glucose polymers, consisting of a backbone of β-(1, 3)–linked β-D-glucopyranosyl units with two β-(1, 6) linked side chains every five β-(1, 3)–linked backbone residues.

Figure 2. Schematic immunomodulating effect of b-glucans after absorption via intestinal mucosa

b-glucans can directly activate macrophages and Dendritic Cells (DCs) in the Peyer’s patches and can induce both, helper T cells (Th) and tumor-specific cytotoxic T. In addition, Fc gamma Receptor (FcgR) provides a critical link between specific humoral responses and cytotoxic T cells Lymphocyte (CTCL).

Figure 3. Principal inflammation-involved biomolecules affected by curative mushrooms: G. lucidum (left), and G. frondosa (right)

Figure 4. Direct anticancer activities of triterpenes ganoderic acid (chemical structure shown in pink inset)

Figure 5. Schematic representation of main putative anticancer cellular mechanisms of β-glucans

^* molecules involved directly and indirectly in the apoptosis. ^# molecules involved directly and indirectly in the blocking of proliferation.

Figure 6. Microbiota dynamics and complexity from birth to adult

Figure 7. Diet and other environmental factors influence gastrointestinal Microbiota (GI) homeostasis or dysbiosis

Figure 8. The gastrointestinal (GI) microbiota functions in maintenance of health, including protective, structural, and metabolic roles