Exosomes are extracellular vesicles secreted by most eukaryotic cells and participate in intercellular communication. The components of exosomes, including proteins, DNA, mRNA, microRNA, long noncoding RNA, circular RNA, etc., which play a crucial role in regulating tumor growth, metastasis, and angiogenesis in the process of cancer development, and can be used as a prognostic marker and/or grading basis for tumor patients. Hereby, we mainly summarized as followed: the role of exosome contents in cancer, focusing on proteins and noncoding RNA; the interaction between exosomes and tumor microenvironment; the mechanisms that epithelial-mesenchymal transition, invasion and migration of tumor affected by exosomes; and tumor suppression strategies based on exosomes. Finally, the application potential of exosomes in clinical tumor diagnosis and therapy is prospected, which providing theoretical supports for using exosomes to serve precise tumor treatment in the clinic.
Long noncoding RNAs (lncRNA) have been associated with various types of cancer; however, the precise role of many lncRNAs in tumorigenesis remains elusive. Here we demonstrate that the cytosolic lncRNA P53RRA is downregulated in cancers and functions as a tumor suppressor by inhibiting cancer progression. Chromatin remodeling proteins LSH and Cfp1 silenced or increased P53RRA expression, respectively. P53RRA bound Ras GTPase-activating protein-binding protein 1 (G3BP1) using nucleotides 1 and 871 of P53RRA and the RRM interaction domain of G3BP1 (aa 177-466). The cytosolic P53RRA-G3BP1 interaction displaced p53 from a G3BP1 complex, resulting in greater p53 retention in the nucleus, which led to cell-cycle arrest, apoptosis, and ferroptosis. P53RRA promoted ferroptosis and apoptosis by affecting transcription of several metabolic genes. Low P53RRA expression significantly correlated with poor survival in patients with breast and lung cancers harboring wild-type p53. These data show that lncRNAs can directly interact with the functional domain of signaling proteins in the cytoplasm, thus regulating p53 modulators to suppress cancer progression. A cytosolic lncRNA functions as a tumor suppressor by activating the p53 pathway. .
Ferroptosis is a newly discovered form of non-apoptotic cell death in multiple human diseases. However, the epigenetic mechanisms underlying ferroptosis remain poorly defined. First, we demonstrated that lymphoid-specific helicase (LSH), which is a DNA methylation modifier, interacted with WDR76 to inhibit ferroptosis by activating lipid metabolism-associated genes, including GLUT1, and ferroptosis related genes SCD1 and FADS2, in turn, involved in the Warburg effect. WDR76 targeted these genes expression in dependent manner of LSH and chromatin modification in DNA methylation and histone modification. These effects were dependent on iron and lipid reactive oxygen species. We further demonstrated that EGLN1 and c-Myc directly activated the expression of LSH by inhibiting HIF-1α. Finally, we demonstrated that LSH functioned as an oncogene in lung cancer in vitro and in vivo. Therefore, our study elucidates the molecular basis of the c-Myc/EGLN1-mediated induction of LSH expression that inhibits ferroptosis, which can be exploited for the development of therapeutic strategies targeting ferroptosis for the treatment of cancer.
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