FOXO1 is crucial in glioblastoma cell tumorigenesis and regulates the expression of SIRT1 to suppress senescence in the brain

FoxO1 promotes ovarian cancer by increasing transcription and METTL14-mediated m6A modification of SMC4

The transcription factor forkhead box protein O1 (FoxO1) is closely related to the occurrence and development of ovarian cancer (OC), however its role and molecular mechanisms remain unclear. Herein, we found that FoxO1 was highly expressed in clinical samples of OC patients and was significantly correlated with poor prognosis. FoxO1 knockdown inhibited the proliferation of OC cells in vitro and in vivo. ChIP-seq combined with GEPIA2 and Kaplan-Meier database analysis showed that structural maintenance of chromosome 4 (SMC4) is a downstream target of FoxO1, and FoxO1 promotes SMC4 transcription by binding to its -1400/-1390 bp promoter. The high expression of SMC4 significantly blocked the tumor inhibition effect of FoxO1 knockdown. Furtherly, FoxO1 increased SMC4 mRNA abundance by transcriptionally activating methyltransferase-like 14 (METTL14) and increasing SMC4 m6A methylation on its coding sequence region. The Cancer Genome Atlas dataset analysis confirmed a significant positive correlation between FoxO1, SMC4, and METTL14 expression in OC. In summary, this study revealed the molecular mechanisms of FoxO1 regulating SMC4 and established a clinical link between the expression of FoxO1/METTL14/SMC4 in the occurrence of OC, thus providing a potential diagnostic target and therapeutic strategy.

LITAF Enhances Radiosensitivity of Human Glioma Cells via the FoxO1 Pathway

Lipopolysaccharide-induced tumor necrosis factor alpha factor (LITAF), also called p53-induced gene 7 (PIG7), was identified as a transcription factor that activates transcription of proinflammatory cytokines in macrophages in response to lipopolysaccharide (LPS). Previous studies have identified LITAF as a potential tumor suppressor in several neoplasms, including prostate cancer, B-NHL, acute myeloid leukemia, and pancreatic cancer. However, the expression and function of LITAF in human glioma remain unexplained. The present study aimed to analyze the regulation of LITAF in gliomas. Data from The Cancer Genome Atlas (TCGA) database revealed that LITAF mRNA expression in glioma tissues was higher than that in normal brain tissues, and lower LITAF expression in gliomas showed a good prognosis in patients who received radiotherapy, by Kaplan-Meier analysis. In our collected specimens, however, LITAF showed low expression in glioma tissues compared to that in the normal brain tissue. Proliferation and apoptosis of glioma cells were not affected by knockdown or overexpression of LITAF in glioma U251, U373, and U87 cells, but LITAF was able to enhance the radiosensitivity of glioma cells. Furthermore, we found that LITAF enhanced radiosensitivity via FoxO1 and its specific downstream targets BIM, TRAIL, and FASLG. Taken together, our present results demonstrate that LITAF expression is decreased in glioma tissues and might enhance radiosensitivity of glioma cells via upregulation of the FoxO1 pathway.

An Interplay between Senescence, Apoptosis and Autophagy in Glioblastoma Multiforme-Role in Pathogenesis and Therapeutic Perspective

Autophagy, cellular senescence, programmed cell death and necrosis are key responses of a cell facing a stress. These effects are partly interconnected, but regulation of their mutual interactions is not completely clear. That regulation seems to be especially important in cancer cells, which have their own program of development and demand more nutrition and energy than normal cells. Glioblastoma multiforme (GBM) belongs to the most aggressive and most difficult to cure cancers, so studies on its pathogenesis and new therapeutic strategies are justified. Using an animal model, it was shown that autophagy is required for GBM development. Temozolomide (TMZ) is the key drug in GBM chemotherapy and it was reported to induce senescence, autophagy and apoptosis in GBM. In some GBM cells, TMZ induces small toxicity despite its significant concentration and GBM cells can be intrinsically resistant to apoptosis. Resveratrol, a natural compound, was shown to potentiate anticancer effect of TMZ in GBM cells through the abrogation G2-arrest and mitotic catastrophe resulting in senescence of GBM cells. Autophagy is the key player in TMZ resistance in GBM. TMZ can induce apoptosis due to selective inhibition of autophagy, in which autophagic vehicles accumulate as their fusion with lysosomes is blocked. Modulation of autophagic action of TMZ with autophagy inhibitors can result in opposite outcomes, depending on the step targeted in autophagic flux. Studies on relationships between senescence, autophagy and apoptosis can open new therapeutic perspectives in GBM.