Background & objective: Recent study found that suramin could inhibit the growth of malignant tumors, but its in vivo effect on lung adenocarcinoma has seldom been reported. This study was to investigate the inhibitory effects of suramin on the growth and metastasis of transplanted lung adenocarcinoma in mice, and explore the mechanisms.
Methods: Lung adenocarcinoma LA795 cells were transplanted into 32 T739 mice. The tumor-bearing mice were randomized into control group, cisplatin (DDP) group, suramin group, and combination (suramin plus DDP) groupû each group contained 8 mice. Different treatments were served since Day 4 after transplantation. All mice were killed 24 days after transplantation. The metastatic tumor foci on the lung in mice were counted. The occurrence rate of lung metastasis and the inhibition rate of metastatic foci were calculated. The volume and weight of tumors were measured. The expression of epidermal growth factor receptor (EGFR), P-selectin and proliferating cell nuclear antigen (PCNA) in tumor tissues were detected by immunhistochemistry.
Results: DDP and suramin used alone or in combination significantly inhibited the growth of LA795 cells in mice (P<0.05), with growth inhibition rates of 34.9%, 23.8% and 57.3%, respectively. The occurrence rate of lung metastasis and the number of metastatic foci on lung surface were significantly lower in suramin group and combination group than in DDP group and control group (P<0.05). The protein levels of EGFR and P-selectin were significantly higher in control group than in DDP group, suramin group, and combination group (157.7+/-6.1 vs. 130.7+/-5.9, 110.3+/-5.8, and 89.2+/-5.4, P<0.05û 134.5+/-5.7 vs. 117.9+/-5.1, 96.2+/-5.4, and 78.3+/-4.5, P<0.01). The S phase fraction of tumor cells was significantly higher in control group than in DDP group, suramin group, and combination group [(89.7+/-3.8)% vs. (68.8+/-4.0)%, (65.2+/-4.2)%, and (51.3+/-4.2)%, P<0.01)].
Conclusion: Suramin could inhibit the proliferation and metastasis of LA795 cells in T739 mice through regulating the expression of EGFR, P-selectin and PCNA.