Mushroom Polysaccharides as Biological Response Modifiers in Cancer Therapy

Introduction

Cancer is the second leading cause of death around the world. Uncontrolled growth and multiplication of abnormal cells is the most common characteristic of malignant cells. The uncontrolled spread of cancer can result in death. In 2030, the estimated mortality due to cancer is thirteen million (Ferlay et al, 2010; Torre et al, 2015). The conventional methods of Cancer treatment include surgery, radiation, and chemotherapy. Radiotherapy is used quite successfully for many forms of cancers while chemotherapy has become an integral part of the multi-disciplinary treatment of cancers and has served also as a palliative measure in cases of advanced cancer. However, cancer treatment by conventional therapies has severe side effects. The adverse effects are greatest on hematopoietic tissue, gastrointestinal mucosa, gonads, and skin. The effect on the hematopoietic tissue of the host is severe which leads to immunosuppression. This in turn negatively affects cancer treatment by making the host vulnerable to opportunistic and pathogenic infections by microorganisms. Both radiotherapy and chemotherapy are known to invariably damage or weaken the patient’s immunological defenses which may have been already damaged by the cancer itself. Furthermore, within the holistic approach of clinical cancer therapy increasing emphasis is being given to patients’ quality of life (QOL) following these above classical treatments. The prolongation of life should not be the only criterion to assess the treatment results. Thus, recent investigations have been channeled toward the development of immunotherapy to target and remove cancer cells. Immunomodulators known as Biological Response Modifiers (BRM) have now evolved as the fourth method of cancer treatment in addition to surgery, radiotherapy, and chemotherapy (Bisht, Bist, & Dhasmana, 2010). Immunostimulating agents would possibly be useful adjuncts to conventional treatments of cancer if they do not interfere with the ability of the conventional treatment to kill tumour cells.

Natural products for the prevention or treatment of tumours are promising chemopreventive agents due to their very low clinical toxicity compared to other chemical anti-tumour drugs (Hashem et al, 2022). In view of developing new anti-tumour compounds with low toxic potential, several polysaccharides from different biological origins, e.g., yeast, algae, bacteria, higher plants, and fungi, have been investigated for anti-tumour and other medicinal properties. The ability of mushrooms to produce useful bioactive metabolites is fascinating and they are considered a prolific resource for drugs. Polysaccharides from mushrooms are generally grouped under immunopotentiators/ immunoinitiators and are called Biological Response Modifiers (BRM) (Sivanesan et al, 2022). Many mushroom polysaccharides are potent anti-tumour agents and are known to complement conventional therapies by reducing side effects such as nausea, bone marrow suppression, anemia, and lowered immunity (Park, 2022). The Discovery and evaluation of new polysaccharides from various medicinal mushrooms as new safe compounds for cancer treatment have become a hot spot of research. Intensive research in this field could contribute to the development of anti-tumour drugs from mushroom polysaccharides which could be safe for prolonged use and also with the least toxicity.