PVT1 and gastric cancer: CircRNA plasmacytoma variant translocation 1 (Circ-PVT1) participates in paclitaxel resistance in gastric cancer as a sponge for miR-124-3p and regulates the EMT marker zinc finger E-box-binding homeobox 1 (ZEB1), thus promoting invasive and drug-resistant phenotypes; circ-MTO1 in hepatocellular carcinoma (HCC) promotes doxorubicin sensitivity by sponging miR-9 and upregulating the tumor suppressor p21, and its downregulation correlates with increased resistance and poorer prognosis[36].