Inhibition of Copper Transporter-1 by Ammonium Tetrathiocarbolybdate in the Treatment of Pancreatic Cancer

  Objective  To examine copper transporter 1 (CTR1) expression in pancreatic carcinoma cells, orthotopic xenograft pancreatic tumor model and clinical samples, and verify the effect of copper chelating agent ammonium tetrathiomolybdate (TM) regulate the expression of CTR1 in pancreatic carcinoma cells and the inhibition of pancreatic carcinoma.

  Methods  The expressions of copper transporter CTR1 and antioxidant protein 1 (ATOX1) in 22 clinical pancreatic ductal carcinoma and paracancer tissues 0.5-1 cm away from the tumor were measured by immunohistochemistry (IHC). PANC-1 cells were used to construct 5 orthotopic xenograft pancreatic tumor of nude mice models. Pancreatic cancer tissues and corresponding normal pancreatic tissues were collected, and the expressions of CTR1 and ATOX1 were detected by IHC and compared with clinical tissues. The proliferation of pancreatic carcinoma cells PANC-1 treated with 10, 30, 50, 100 μmol/L TM for 24 h, 48 h, 72 h was measured by CCK8 assay. The migration abilities of PANC-1 cells treated with 50 μmol/L TM for 24 h, 48 h were detected by scratch test. The expressions of CTR1, vascular endothelial growth factor (VEGF) and CyclinD1 proteins in PANC-1 cells treated with 10, 30, 50, 100 μmol/L TM for 48 h were measured by Western blot. Then the subcutaneous tumor-bearing model of nude mice were established with PANC-1 cells, and the growth of tumor was observed after oral administration of 0.3 mg/d and 1.0 mg/d of TM, respectively.

  Results  The immunohistochemical results indicated that 19 of the 22 clinical pancreatic ductal cancer tissues of carcinoma patients had high expression of CTR1, and the same high expression of CTR1 was found in the orthotopic transplanted tumor tissues of PANC-1 nude mice. The proliferation inhibition of PANC-1 cells increased with the concentration of TM increased and the treatment time prolonged. The expressions of intracellular CTR1, VEGF and CyclinD1 all decreased with the concentration of TM increased. The cell migration ability decreased after the PANC-1 cells treated with TM. The tumor growth of PANC-1 tumor-bearing nude mice was inhibited after different doses of TM were delivered. The reduction in tumor volume and weight was more pronounced in the high-dose TM group (P<0.05).

  Conclusion  The expression of CTR1 is abnormally elevated in pancreatic carcinoma, and treatment with copper chelating agent for this target may help to inhibit pancreatic carcinoma.