Prostate cancer-selective anticancer action of an oxindole derivative via HO-1-mediated disruption of metabolic reprogramming.

Prostate cancer, the second leading cause of cancer-related mortality in men, exhibits distinct metabolic reprogramming involving zinc and citrate metabolism. This study investigated whether targeting this unique metabolic profile could offer an effective therapeutic approach. A series of novel oxindole derivatives were synthesized and evaluated for their inhibitory effects on transcription factors (TFs) and antiproliferative activity across various cancer cell lines. Among these, compound 3D showed the strongest inhibition of master TFs (HIF-1α, c-Myc, and SP-1) and demonstrated selective antiproliferative activity in prostate cancer cells. In PC-3 and LNCaP cells, compound 3D suppressed aerobic glycolysis by downregulating lactate-modulating genes (LDHA, MCT1/4, and CAIX) and the zinc influx transporter (ZIP1), without affecting the zinc efflux transporter (ZnT4). Notably, 3D selectively increased heme oxygenase-1 (HO-1) levels in prostate cancer cells, as shown by the proteome profiler oncogene array assay and confirmed by Western blotting. This response was reversed by ZnCl2 treatment. The decreases in LDHA, mitochondrial mass (measured by FACS), and cell proliferation induced by compound 3D were blocked by HO-1-IN-1, an HO-1 inhibitor, and ZnCl2. Furthermore, 3D induced a more pronounced reduction in the oxygen consumption rate (OCR) than in the extracellular acidification rate (EACR), indicating a strong effect on oxidative metabolism. 3D exhibited dose-dependent antitumour efficacy in vivo comparable to that of docetaxel. These findings reveal that the oxindole derivative 3D substantially lowers intracellular zinc levels, yielding potent antitumour effects in prostate cancer through HO-1 upregulation, which impairs mitochondrial function more significantly than aerobic glycolysis.