Fig. 2

Exosomal circRNAs affect tumor homing. a Epithelial ovarian cancer (EOC)-derived exosomes containing circPUM1, which targets MMP2 transcripts, are transported to the peritoneum to regulate tumor metastasis. b In pancreatic cancer, exosomes containing circIRAS enter microvascular endothelial cells to compromise endothelial barrier function and to promote liver metastasis by targeting RhoA. c The CXCR4/CXCL12 axis is critical for cancer metastasis. In lung adenocarcinoma, exo-hsa_circRNA_0056616 participates in lymph node metastasis by targeting CXCR4 and affecting TAM infiltration. CXCR4 expression on TAMs or tumor cells drives the spread to the organs expressing CXCL12, which has been identified as regulated by circ_0020710 in melanoma. d In bladder cancer urine supernatant, hsa_circ_0137439 in exosomes or other vehicles targets metadherin (MTDH), which can bind to the vasculature of distant organs to promote metastasis (The solid arrow indicates verified observations, while the dotted arrow indicates hypothesis)