The malignant role of exosomes in the communication among colorectal cancer cell, macrophage and microbiome.

Colorectal cancer (CRC) is a complex and heterogeneous malignant cancer characterized by its high prevalence and poor prognosis. Among different etiologies, impairment of immune surveillance and dysbiosis are important events to mediate the invasion and metastasis of CRC. Although aberrant distribution of macrophages and microbiota exhibits distinct properties to modulate the malignant behaviors of CRC, the crosstalk among macrophages, microbiomes and tumor cells remains unclear. Exosomes are intercellular messengers carrying different cargo to regulate the biological and pathologic changes of recipient cells. CRC-derived exosomes can educate macrophages and facilitate the angiogenesis and establishment of premetastatic niche. Meanwhile, exosomes from macrophages and microbiome can regulate the tumor microenvironment for tumor progression and dissemination. The aim of this review is to highlight the innovative role of exosomes in the pathogenesis of CRC. Theoretical elaboration of the underlying mechanism provides valuable treating targets of CRC.