Background Currently, resistance against cisplatin (DDP) is a frequent problem for the success of advanced gastric carcinoma (GC) chemotherapy. Here, we sought to investigate the function of activating transcription factor 3 (ATF3) n GC chemoresistance. Methods Expression of ATF3 was determined in GC cell lines (MNK45, SGC7901, and BGC823) and cisplatin (DDP)-resistant cells (SGC7901/DDP and BGC823/DDP). Biological informatics was performed to analyze ATF3 expression and prognosis in GC patients. Cisplatin resistance was evaluated. Ferroptosis was detected after ATF3 transfection of cells. The underlying molecular mechanism was also investigated. Results Transcripts of ATF3 were decreased in GC cells and GC tissues. Kaplan–Meier plotter analysis revealed that ATF3 expression was positively related to the overall survival of GC patients. In particular, lower levels of ATF3 were observed in cisplatin-resistant SGC7901/DDP and BGC823/DDP relative to their parental cells. Notably, ATF3 elevation sensitized cisplatin-resistant cells to cisplatin. Mechanically, compared with parental cells, SGC7901/DDP and BGC823/DDP cells exhibited lower ferroptosis evident by lower ROS, MDA and lipid peroxidation and higher intracellular GSH levels. However, ATF3 elevated ferroptosis in SGC7901/DDP and BGC823/DDP cells. Intriguingly, ATF3 overexpression together with ferroptosis activator erastin or RSL3 treatment further enhanced ferroptosis and cisplatin resistance; however, the ferroptosis suppressor liproxstatin-1 reversed the function of ATF3 in ferroptosis and cisplatin resistance. Additionally, cisplatin-resistant cells exhibited stronger activation of Nrf2/Keap1/xCT signaling relative to parental cells, which was restrained by ATF3 up-regulation. Importantly, restoring Nrf2 signaling overturned ATF3-mediated ferroptosis and cisplatin resistance. Conclusion ATF3 may sensitize GC cells to cisplatin by induction of ferroptosis via blocking Nrf2/Keap1/xCT signaling, supporting a promising therapeutic approach for overcoming chemoresistance in GC.

Liver cancer in men is the fifth most frequently diagnosed cancer worldwide. Human Krüppel-like factor (KLF9) gene, localized on human chromosome 9q13, has been implicated in mediating a diverse range of biological processes including stem cell maintenance and differentiation of T- and B-lymphocytes. In this study, we confirmed that the levels of KLF9 mRNA and protein were lower in hepatocellular carcinoma (HCC) tissue compared to normal tissue. In addition, we confirmed that upregulation of KLF9 inhibited cell proliferation and mobility and induce apoptosis in HepG2 cells depending on programmed cell death protein 5 (PDCD5) expression. However, no interaction was found between KLF9 and PDCD5 using fluorescence resonance energy transfer (FRET) and co-immunoprecipitation (co-IP). We confirmed that PDCD5 overexpression stimulated the promoter activities of KLF9 by luciferase reporter assays.

Liver cancer in men is the fifth most frequently diagnosed cancer worldwide. Programmed cell death 5 (PDCD5) is an apoptosis related gene and plays an important role in the pathogenesis and development of cancer. In this study, we confirmed that the levels of PDCD5 mRNA and protein were lower in hepatocellular carcinoma (HCC) tissue compared to normal tissue. PDCD5 expression was significantly associated with HBV infection, tumor number, lymph node metastasis and the survival time of the patients with HCC. In addition, the serum levels of PDCD5 and AFP in the patients were significantly positively correlated. We also confirmed that upregulation of PDCD5 was able to inhibit cell proliferation and mobility, induce apoptosis and G1 arrest. Interestingly, PDCD5 also inhibited proteasome activity similarly to the proteosome inhibitor MG132. PDCD5 could be considered as a reliable marker of favorable prognosis of HCC patients.

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Liver cancer is the fifth most frequently diagnosed type of cancer in men worldwide. Recombinant human programmed cell death 5 (rhPDCD5) has been shown to enter a variety of cells by clathrin-independent endocytosis. Tissue specimens from 32 hepatocellular carcinoma (HCC) patients were collected for analysis of PDCD5 expression using ELISA. It was confirmed that the pre‑operative serum levels of PDCD5 protein in patients with HCC were significantly lower than the post‑operative serum levels. Moreover, the serum PDCD5 levels were significantly correlated with portal invasion and lymph node metastasis. rhPDCD5 inhibited cell proliferation as indicated by an MTT assay, and induced apoptosis and S-phase arrest in HCC cells as demonstrated by flow cytometric analysis. Furthermore, rhPDCD5 suppressed tumor growth in established xenograft tumor models. In addition, Pitstop2 was used to block clathrin-dependent endocytosis (CDE), which confirmed that the anti‑tumor effect of rhPDCD5 in HCC cells is mediated via CDE.