Three Pathways of Cancer Cachexia: Inflammation, Changes in Adipose Tissue and Loss of Muscle Mass-The Role of miRNAs.

According to the World Health Organization, in 2018, cancers, along with over 18 million new cases and over 9.5 million deaths remained one of the main causes of mortality globally. Cancer-cachexia, also called wasting syndrome is a complex, multifactorial disorder characterized by progressive skeletal muscle mass loss, with or without adipose tissue atrophy. It is considered as a state of cancer-related malnutrition (CRM) accompanied by inflammation, that is irreversible despite the introduction of nutritional support. Indication of markers of pre-cachectic state seems to be urgently needed. Moreover, such markers have also potential to be used in the assessment of the effects of anti-cachexia treatment, and prognosis. miRNAs are non-coding RNA molecules that are about 20-30 nucleotides long. Single miRNA has the potential to control from few dozen to several hundred different genes. Despite the fact, that the number of miRNAs keep growing. we are making steady progress in establishing regulatory targets and their physiological levels. In this review we described the current knowledge on the impact of miRNAs on processes involved in cancer cachexia development: inflammation, adipose tissue remodelling, and loss of muscle mass both in animal models and the human cohorts. The available studies suggest that miRNAs, due to their properties, e.g., the possibility of regulating even hundreds of different genes, signalling pathways, and biological processes by one molecule, but also due their stability in biological material, the fact, that the change in their level reflects the disease status or the response to the applied treatment, they have great potential to be used as valuable biomarkers in the diagnosis, treatment, and prognosis of cancer cachexia.