PTGS2 and gastric cancer: On the basis of previous studies, this experiment focused on exploring the role of ω-3, ω-6, PGE2, and PGE3 in gastric cancer metastasis, and the results showed that the expression of PGE2 and COX-2 in gastric cancer cell lines was closely related to their liver metastasis, that is, PGE2 and COX-2 were expressed in cell lines MKN45 and MKN74 with high liver metastasis, while PGE3 and COX-1 were expressed in cell lines with high and low liver metastases.