The methylated PSMA3-AS1 and MIR22HG, which were upregulated in GCSCs sorted from the solid tumors of a patient with gastric cancer and two distinct gastric cancer cell lines (HGC-27 and MGC-803), suppressed apoptosis and promoted the stemness of three types of GCSCs, thus promoting tumorigenesis. The gene discussed is PSMA3; the disease is gastric cancer.