The Role of Mitogen-Activated Protein Kinases and Their Relationship with NF-κB and PPARγ in Indomethacin-Induced Apoptosis of Colon Cancer Cells

Abstract Background: Nuclear factor−erythroid 2−related factor 2 (Nrf2) has a key function in promoting chemoresistance in various cancers. PD-L1 is one of the downstream targets of Nrf2 signaling pathway, having some beneficial impacts on tumors growth by inhibition of the immune system. The aim of this study was to investigate the potential role of Nrf2- PD- L1 axis in the promotion of oxaliplatin resistance in colon cancer cells. Result: Our data revealed that Nrf2 and PD-L1 mRNA expressions were markedly higher in tumor tissues compared to margin tissues. PD-L1 mRNA expression level was also increased in the resistant cells. However, Nrf2 expression was decreased and increased in SW480/Res and LS174T/Res cells, respectively. Nrf2 inhibition through siRNA in SW480/Res and LS174T/Res decreased the IC50 values of oxaliplatin. Inhibition of Nrf2 significantly increased oxaliplatin-induced apoptosis and reduced migration in SW480/Res cells when accompanied with oxaliplatin. Conclusion: Our study suggests that effective inhibition of Nrf2/PD-L1 signaling pathways can be considered as a novel approach to improve oxaliplatin efficacy in colon cancer patients.

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The Pivotal Role of PAO in CDK Inhibitors (Roscovitine and Purvalanol)- Triggered Apoptosis in PUMA Null HCT116 Colon Cancer Cells

10.31487/j.ijcst.2021.01.03 ◽

2021 ◽

pp. 1-10

Author(s):

Ajda Coker-Gurkan ◽

Burcu Ayhan-Sahin

Keyword(s):

Cell Cycle ◽

Colon Cancer ◽

Cancer Cells ◽

Cyclin B1 ◽

Mapk Signaling ◽

Cdk Inhibitors ◽

Colon Cancer Cells ◽

Drug Induced ◽

Induced Apoptosis

Background: Cycline-dependent kinase inhibitors (CDKi); roscovitine and purvalanol, are promising anti-cancer drugs due to their strong anti-proliferative effectiveness due to activation of PA catabolism. Besides transforming acetylated spermine and spermidine into spermidine and putrescine, respectively, polyamine oxidase (PAO) also generates hydrogen peroxide in high concentrations as a by-product. PAO was assumed as a pivotal key molecule during drug-induced apoptosis in cancer cells. Our aim is to reveal the role of PAO action in CDKi-triggered apoptosis in Puma knock-out HCT116 colon cancer cells. Methods: HCT116 wt and HCT116 Puma-/- cells were treated with Roscovitine and Purvalanol and cell viability and apoptosis were determined. Protein was isolated from treated and untreated cells and key molecules of cell cycle control and polyamine pathways were investigated at translational level. Polyamine content was determined by HPLC for all conditions. MDL-72527 was used as a PAO inhibitor and apoptotic cell death was analysed. Results: Roscovitine and purvalanol induced apoptosis and increased the cytotoxic responses in HCT116 wt and HCT116 Puma-/- colon carcinoma cell lines by modulating CDK1, 4, cyclin-B1, D3. Both, CDKi altered intrinsic apoptotic pathways in HCT116 wt. Whereas, drug-induced apoptosis occurred caspase-independent in Puma-/- colon cancer cells. Roscovitine and purvalanol up-regulated polyamine catabolic enzymes, whereas CDK inhibitors decreased the polyamine levels in HCT116 wt and HCT116 Puma-/- colon cancer cells. In addition, PAO inhibitor MDL72527 prevented drug-induced apoptosis. Conclusion: PAO expression profile might be a critical target in CDK inhibitors-triggered apoptosis in HCT116 colorectal cancer cells. Thus, MAPK signaling pathway relations with cell cycle and polyamine catabolic pathway investigations are in progress.

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