Metformin mediates AMPK/KIF1B signalling pathway to inhibit metastasis in bladder cancer cells

Abstract Background To investigate the inhibitory effect of metformin on metastasis of bladder cancer cells and its potential mechanism. Methods The CCK-8 method and RTCAxCELLigence cell function analyzer were used to monitor and evaluate metformin activity changes and migration inhibition of SW780, RT4 and UMUC3. On this basis, Western blotting was used to evaluate the expression of AMPKα/P-AMPKα, mTOR, AKT/P-AKT and KIF1B antibodies in bladder cancer cells after adding metformin. In vivo, the metastatic inhibitory effect of metformin on bladder cancer was experimentally assessed by establishing a hematogenous lung metastasis model of bladder cancer in C57BL/6 mice by MB49 cells. Then the expression of AMPKα/P-AMPKα and KIF1B antibodies was again assessed in the tumour tissues of the two groups of mice using Western blotting. Results Low concentration of metformin can significantly inhibit the proliferation of SW780 and UMUC3, and a high concentration of metformin can significantly inhibit the proliferation of RT4. The IC50 of the three cells was 26.0 ± 1.4 mM, 32.9 ± 5.3 mM and 20.0 ± 3.4 mM, respectively. The migration of SW780 and UMUC3 was significantly inhibited by metformin when the concentration of metformin was more than 5MM and the time of action was more than 72h (P < 0.05). After adding metformin, P-AMPK was increased in RT4 and UMUC3, and the expression of KIF1B, AKT and mTOR antibodies was decreased. In vivo, The mean time of tumour formation in the metformin group was 34.5 ± 8.3 days, significantly longer than in the control group (24.8 ± 3.7 days, P = 0.035). In addition, the median survival time of mice in the metformin group was 40 days (P = 0.016). Compared with the control group, p-AMPK was up-regulated, and KIF1B was down-regulated in the metformin group. Conclusions Metformin can effectively inhibit the proliferation, migration, and invasion of SW780 and UMUC3 cells in vitro. Metformin can inhibit the migration of MB49 cells in vivo and increase mice's survival time. The mechanism of inhibiting the migration of UMUC3 in vitro and MB49 in vivo may be mediated by the AMPK pathway, which directly or indirectly inhibits the expression of its downstream KIF1B gene by activating P-AMPK.