Introduction: The importance of angiogenesis in tumour growth is well established. Strong evidence suggests that the progression of many primary and metastatic tumours requires an “angiogenic switch” to promote adequate vascularization and blood supply. There are on going investigations to identify compounds which can effectively suppress angiogenesis. Copper plays a key role in multiple steps along the angiogenesis pathway, and it has been established as an essential cofactor for basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF) and angiogenin. Tetrathiomolybdate (TM) is a powerful copper chelator, and previous studies showed its promising role as an anti-angiogenic compound capable of suppressing several pro-angiogenic factors. This study investigates the effects of long-term TM treatment on the local and metastatic progression of head and neck squamous cell carcinoma (SCC). Methods: An animal model was used to study the effects of TM on the progression of head and neck SCC. UM- SCC- 11B was selected as a highly proliferative cell line. Nude mice were inoculated with 1 million cells subcutaneously in the flank, and tumour progression was monitored for 12 weeks. Mice received either TM or water by daily oral gavaging for the TM and the control groups, respectively. The treatment was initiated 2 weeks prior to tumour inoculation and was continued until the end of the experiment. Blood was collected biweekly to monitor CP, as well as makers of angiogenesis, including bFGF, VEGF, IL-8. TM dose was adjusted to maintain 20-30% reduction in serum ceruloplasmine (CP). At time of sacrifice both tumours and lungs were dissected and fixed. Microscopic metastases were counted for 60 lung sections per group. Tumour sections were stained for VEGF, as well as CD31 to assess vascular density. Results: TM at 0.7 - 1.0 mg/mouse was effective in suppressing serum CP to 20-30% of baseline levels. Median tumour size in the TM-treated group was significantly smaller than controls (p ≤ 0.05). TM group had significantly more gross necrosis (p <0.05); lung metastases were also significantly decreased (p <0.05). There is some suppression of angiogenic factors detected in serum. CD 31 staining showed about 87% decrease in vessels formation in TM treated mice as compared to controlled. Conclusions: These results support the inhibitory role of TM on the development of distant metastases. The decreased vascular density at in the primary tumor can explains the higher necrosis observed in the TM group. The suppression in VEGF expression as well as serum levels suggests its potential use as a biomarker for treatment effects.
[Proc Amer Assoc Cancer Res, Volume 47, 2006]