Molecular mechanisms involved in the anticancer activities of probiotics and postbiotics

Probiotics promote host health and have shown potential as both prophylactics and adjuvants for the treatment of several human diseases. Therefore, medical interest in these microorganisms has increased rapidly. Recently, probiotics along with postbiotics, i.e., their inanimated counterparts, have been explored for their capacity to treat cancer, a vast group of diseases characterized by uncontrolled cell proliferation, which represents a major global health burden and is the second leading cause of death worldwide. The present review collects and discusses recent preclinical studies addressing the anticancer action of probiotics and postbiotics from lactic acid bacteria and bifidobacteria, and describes the molecular mechanisms by which they hamper some major hallmarks of tumor cells, i.e., through stimulation of apoptosis, blockade of proliferation and the cell cycle, inhibition of metastasis, metabolic interference, activation of the host anti-cancer immune response. The medical use of probiotics should rely on an extensive understanding of the molecular and cellular mechanisms underlying their anticancer activities. Accordingly, this review aims to provide insights into the advancements and limitations of the current research in this field, which is strongly needed to provide solid rationales for the prospective clinical use of probiotics in cancer.