Piperlongumine-inhibited TRIM14 signaling sensitizes glioblastoma cells to temozolomide treatment

Aims: Glioblastoma multiforme (GBM) is the most aggressive and mortal primary glioma in adults. Temozolomide (TMZ) is a first-line clinical chemotherapeutic drug. However, TMZ resistance causes treatment failure in patients. Thus, exploring effective adjuvant drugs for GBM is crucial. Piperlongumine (PL), a bioactive alkaloid isolated from long pepper, possesses promising anticancer abilities. However, PL-mediated cytotoxic mechanisms in GBM are still unclear. We attempted to identify PL-regulated networks in suppressing GBM malignancy. Main methods and key findings: PL treatment significantly induced more apoptotic death in several GBM cell lines than in normal astrocytes. Decreased cell invasion, colony generation, and sphere formation, and enhanced TMZ cytotoxicity were found in PL-treated cells. Through RNA sequencing, PL-mediated transcriptomic profiles were established. By intersecting PL-downregulated genes, higher expressing genes in The Cancer Genome Atlas (TCGA) tumor tissues, and risk genes in three different GBM databases, tripartite motif-containing 14 (TRIM14) was selected. Higher TRIM14 expression was correlated with poor patient survival, and it existed in tumor samples, in mesenchymal type of GBM patients, and in GBM cells. PL significantly reduced TRIM14 expression through activating the p38/MAPK pathway. Overexpression or knockdown of TRIM14 influenced cell growth, PL-inhibited cell viability, invasion, colony generation, and sphere formation. Finally, using a gene set enrichment analysis, genes positively correlated with TRIM14 levels were enriched in epithelial-to-mesenchymal transition signaling. TRIM14 overexpression attenuated PL-regulated mesenchymal transition signaling. Significance: PL inhibited TRIM14 signaling through activating the p38/MAPK pathway to inhibit GBM malignancy. Our findings may provide better insights and directions for future GBM therapies.