Crosstalk of proteins, miRNAs involved in metastatic and epithelial–mesenchymal transition pathways

ABSTRACT Metastasis is an intricate process which involves the proliferation of a tumour to distant parts of the body from its original site. To successfully colonize a distant area in the body, a cancer cell must complete a series before it becomes clinically detectable. These steps involve a large number of proteins indulging in various pathways. Proteins such as matriptase require serine protease for activation, processing and degradation of any signal. Stim1/Orai1 controls the Ca2+ channel which is important for cell migration. Sox protein plays a vital role in various cellular activities and the disruption of its gene plays a role in instigating invasion. Unlike the above three, Metadherin has an inhibitory role to play. Protein inhibits the epithelial–mesenchymal transition (EMT); thus the loss of metadherin evokes metastasis. These proteins play a role in amalgamation with various pathways such as the AKT E-cadherin and EMT pathway, PI3K/AKT pathway, integrin-linked kinase (ILK) – integrin signalling pathway, PI3K/AKT and notch signalling pathway. In this article, we have combined various proteins and pathways that work in coordination to result in a metastatic colony. There are two major events that occur during metastasis, that is epithelial–mesenchymal transition and mesenchymal–epithelial transition. Both these events are an indispensable part for metastasis.