Silhouette of Probiotics in the Regulation of miRNAs and lncRNAs in Carcinogenesis and Metastasis: Is It a Silver Lining or a Cross to Bear.

Cancer is a genomically complex and multifaceted disease. Wealth of information distilled through decades of high-throughput research has revealed a broad spectrum of oncogenic signaling cascades, immunological evasion, and drug resistance, which play a steering role in carcinogenesis and metastasis. Noncoding RNAs have also emerged as key players in the regulation of multiple stages of cancer progression and metastatic spread of cancer cells to secondary sites. The concept of probiotics has started to gain limelight due to its ability to pharmacologically modulate the host microbiome and the immunological responses. The genomics era has provided impetus for the discovery and characterization of bacterial probiotic effector molecules that stimulate specific responses. We have witnessed an exponential increase in the seminal studies which provided proof-of-concept about the mechanistic regulation of cell signaling pathways and noncoding RNAs by probiotics. These exciting and groundbreaking studies ignited an outburst of data generated using several "omics" technologies. In this chapter, we have provided a summary of seminal studies associated with the anticancer and antimetastatic role of probiotics in animal models. However, circumstantial evidence has also underlined tumor-promoting role of probiotics in animal model studies. Therefore, there is a need to scrupulously reinterpret the existing pieces of evidence related to conflicting data about pro-tumorigenic and tumor-inhibitory roles of probiotics. We also critically summarized how probiotics modulated noncoding RNAs to prevent/inhibit cancer progression. Surprisingly, probiotics-mediated regulation of noncoding RNAs has not been comprehensively explored in different cancers. In accordance with this approach, in-depth analysis of target long noncoding RNAs and circular RNAs by probiotics will allow the researchers to develop near-to-complete signaling landscape to reap the full benefits of the medicinal significance of probiotics.