Consistent with the results demonstrated in colon and pancreatic cancer cells [46–49], both direct 8-HOA treatment and endogenous 8-HOA resulting from D5D-KD and DGLA treatment in MDA-MB 231 cells upregulated AcH3 (substrate of histone deacetylase or HDAC) and γH2AX (DNA damage marker, Fig. 8a), indicating that 8-HOA can suppress cancer cell growth by inhibiting HDAC and inducing DNA damage. This evidence concerns the gene HDAC9 and cancer.