Research Paper Volume 13, Issue 18 pp 21914—21940

Metformin-induced chemosensitization to cisplatin depends on P53 status and is inhibited by Jarid1b overexpression in non-small cell lung cancer cells

Sub-lethal dose of cisplatin inhibits P53 accumulation in a Jarid1b-dependent manner. Sub-lethal dose of cisplatin in the A549 cells downregulates TP53 expression even after 30 days post-treatment (A). Western blot analysis shows that A549Res has lower expression of P53 compared to A549. Treatment with Jarid1b inhibitor PBIT avoid metformin-induced downregulation of P53 levels (B). Overexpression of TP53 using AdCMVp53 expressing virus (C) restores metformin-induced chemosensitization to cisplatin on A549Res as seen by DNA fragmentation (pD) and caspase 3 and 7 activation assay (pE), while treatment with pifithrin-μ protect from metformin and cisplatin combination in the DNA fragmentation (pD, E respectively). High expression of Jarid1b (pF) or low expression of TP53, despite p=0.059 (G) indicate poor prognosis for patients with lung adenocarcinoma. DNA fragmentation assay data represents the mean of three independent experiments and caspase 3 and 7 activation assay represents the mean of two independent experiments.

Figure 3. Sub-lethal dose of cisplatin inhibits P53 accumulation in a Jarid1b-dependent manner. Sub-lethal dose of cisplatin in the A549 cells downregulates TP53 expression even after 30 days post-treatment (A). Western blot analysis shows that A549Res has lower expression of P53 compared to A549. Treatment with Jarid1b inhibitor PBIT avoid metformin-induced downregulation of P53 levels (B). Overexpression of TP53 using AdCMVp53 expressing virus (C) restores metformin-induced chemosensitization to cisplatin on A549Res as seen by DNA fragmentation (p<0.001) (D) and caspase 3 and 7 activation assay (p<0.01) (E), while treatment with pifithrin-μ protect from metformin and cisplatin combination in the DNA fragmentation (p<0.05) and caspase 3 and 7 activation assay (p<0.05) (D, E respectively). High expression of Jarid1b (p<0.05) (F) or low expression of TP53, despite p=0.059 (G) indicate poor prognosis for patients with lung adenocarcinoma. DNA fragmentation assay data represents the mean of three independent experiments and caspase 3 and 7 activation assay represents the mean of two independent experiments.