Abstract:

Background and purpose: Pancreatic cancer is a highly malignant disease. Most patients are in advanced stage upon diagnosis. Systemic chemotherapy is an important treatment method, but the chemotherapy drug resistance to tumors brings many problems to clinical treatment. As a commonly used chemotherapy drug, paclitaxel can induce apoptosis in tumor cells. The FBW7 gene is a tumor suppressor gene, and the loss of its function can lead to tumor occurrence and progression. Research has shown that it has the effect of promoting tumor cell apoptosis and inhibiting tumor proliferation. In addition, this gene has been proven to promote apoptosis and ferroptosis, which increase the effect of chemotherapy drugs. Pyroptosis is a programmed cell death mode mediated by gasdermin (GSDM) protein, and this cell death is often accompanied by inflammatory reactions. This study aimed to investigate whether FBW7 gene can promote the anti-tumor effect of paclitaxel by increasing pyroptosis. Methods: A PANC-1 cell line overexpressing FBW7 was constructed using lentivirus transfection. The correlation between FBW7 and GSDME gene expressions was detected by immunohistochemistry in clinical samples, and the expression levels of mRNA and protein were detected by real-time fluorescence quantitative polymerase chain reaction (RTFQ-PCR) and Western blot. We observed the morphological changes of cells treated with paclitaxel under light microscopy. Cell counting kit-8 (CCK-8) was used to detect the effect of paclitaxel on cell viability, and flow cytometry and lactate dehydrogenase (LDH) release assay were performed to detect the effect of paclitaxel on cell death. Western blot was used to detect caspase-3 and GSDME activation after paclitaxel treatment. Results: RTFQ-PCR and Western blot experiments showed that overexpression of FBW7 gene increased the expression of GSDME. Immunohistochemical staining of pathological sections of clinical patients also showed that the expressions of FBW7 and GSDME genes was positively correlated in vivo. Flow cytometry and LDH release experiments showed that the level of cell death in pancreatic cancer cell line PANC-1 overexpressing FBW7 was significantly increased compared with its empty vector (EV) cells after being treated with paclitaxel. Under light microscopy, it was observed that the number of cells with pyroptosis was significantly higher in PANC-1 cell lines overexpressing FBW7 than in EV cells. The CCK-8 experiment results showed that the cell viability was significantly lower in FBW7 overexpressed cell lines than in EV cells after paclitaxel treatment. Western blot experiment results showed that after pancreatic cancer cell line PANC-1 was treated with paclitaxel, the protein expressions of active-caspase-3 and GSDME-NT in FBW7 overexpression cell lines increased, which proved that they had more obvious activation, indicating that the FBW7 gene can increase the sensitivity of PANC-1 cells to paclitaxel through caspase-3/GSDME signaling pathway induced cell pyroptosis. Conclusion: FBW7 can increase the sensitivity of pancreatic cancer cells to paclitaxel by increasing the expression of GSDME, which is realized through caspase-3/GSDME pathway.

Key words: Pancreatic cancer, FBW7, GSDME, Pyroptosis, Sensitivity