ZBTB7A suppresses glioblastoma tumorigenesis through the transcriptional repression of EPB41L5

ZBTB7A interferes with the RPL5-P53 feedback loop and reduces endoplasmic reticulum stress-induced apoptosis of pancreatic cancer cells

Endoplasmic reticulum (ER) stress is a primary mechanism leading to cell apoptosis, making it of great research interests in cancer management. This study delves into the function of ribosomal protein L5 (RPL5) in ER stress within pancreatic cancer (PCa) cells and investigates its regulatory mechanisms. Bioinformatics predictions pinpointed RPL5 as an ER stress-related gene exhibiting diminished expression in PCa. Indeed, RPL5 was found to be poorly expressed in PCa tissues and cells, with this reduced expression correlating with an unfavorable prognosis. Moreover, RPL5 overexpression led to heightened levels of p-PERK, p-eIF2α, and CHOP, bolstering the proapoptotic effect of Tunicamycin, an ER stress activator, on PCa cells. Additionally, the RPL5 overexpression curbed cell proliferation, migration, and invasion. Tunicamycin enhanced the binding between RPL5 and murine double minute 2 (MDM2), thus suppressing MDM2-mediated ubiquitination and degradation of P53. Consequently, P53 augmentation intensified ER stress, which further enhanced the binding between RPL5 and MDM2 through PERK-dependent eIF2α phosphorylation, thereby establishing a positive feedback loop. Zinc finger and BTB domain containing 7A (ZBTB7A), conspicuously overexpressed in PCa samples, repressed RPL5 transcription, thereby reducing P53 expression. Silencing of ZBTB7A heightened ER stress and subdued the malignant attributes of PCa cells, effects counteracted upon RPL5 silencing. Analogous outcomes were recapitulated in vivo employing a xenograft tumor mouse model, where ZBTB7A silencing dampened the tumorigenic potential of PCa cells, an effect reversed by additional RPL5 silencing. In conclusion, this study suggests that ZBTB7A represses RPL5 transcription, thus impeding the RPL5-P53 feedback loop and mitigating ER-induced apoptosis in PCa cells.

Predictive value of procollagen c-protease enhancer protein on the prognosis of glioma patients

Procollagen c-protease enhancer protein (PCOLCE) performs an essential action in improving the recreation of procollagen c-protease and promoting the reconstruction of extracellular matrix. High PCOLCE expression was associated with a negative prognosis of stomach cancer, ovarian cancer, and osteosarcoma. The goal of this work is to investigate the function of PCOLCE in glioma. Multiple bioinformatics techniques have been employed to investigate the roles of PCOLCE in glioma, consisting of the correlation between PCOLCE and prognosis, immune checkpoints, immune cell infiltrates, and tumor microenvironment (TME). The gene ontology (GO) annotations and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were used to assess the potential function of PCOLCE in glioma. PCOLCE was found to be increased in glioma. We revealed that PCOLCE was a potential prognostic factor and related to tumor grade. Up-regulated PCOLCE was related to poor prognosis in lower-grade glioma (LGG), glioblastoma multiforme (GBM), and recurrent glioma. PCOLCE was correlated with immune cell infiltration, particularly B cells, CD4+ T cells, macrophages, neutrophils, and dendritic cells (DCs) in LGG, and DCs infiltration in GBM. PCOLCE was co-expressed with many genes related to the immune and the immune checkpoint. In addition, glioma patients with low expression of PCOLCE had a higher response to the immunological checkpoint blockade (ICB). Additionally, PCOLCE may exert its roles via several immune-related biological processes or pathways, such as leukocyte migration, activation of T cells, adaptive immune response, neutrophil-mediated immunity, NF-κB, and TNF signaling pathways. In conclusion, PCOLCE may be a new immune-related gene and regulate tumor development through immunological pathways.

Epigenetic remodeling to improve the efficacy of immunotherapy in human glioblastoma: pre-clinical evidence for development of new immunotherapy approaches

BACKGROUND

Glioblastoma multiforme (GBM) is a highly aggressive primary brain tumor, that is refractory to standard treatment and to immunotherapy with immune-checkpoint inhibitors (ICI). Noteworthy, melanoma brain metastases (MM-BM), that share the same niche as GBM, frequently respond to current ICI therapies. Epigenetic modifications regulate GBM cellular proliferation, invasion, and prognosis and may negatively regulate the cross-talk between malignant cells and immune cells in the tumor milieu, likely contributing to limit the efficacy of ICI therapy of GBM. Thus, manipulating the tumor epigenome can be considered a therapeutic opportunity in GBM.

METHODS

Microarray transcriptional and methylation profiles, followed by gene set enrichment and IPA analyses, were performed to study the differences in the constitutive expression profiles of GBM vs MM-BM cells, compared to the extracranial MM cells and to investigate the modulatory effects of the DNA hypomethylating agent (DHA) guadecitabine among the different tumor cells. The prognostic relevance of DHA-modulated genes was tested by Cox analysis in a TCGA GBM patients' cohort.

RESULTS

The most striking differences between GBM and MM-BM cells were found to be the enrichment of biological processes associated with tumor growth, invasion, and extravasation with the inhibition of MHC class II antigen processing/presentation in GBM cells. Treatment with guadecitabine reduced these biological differences, shaping GBM cells towards a more immunogenic phenotype. Indeed, in GBM cells, promoter hypomethylation by guadecitabine led to the up-regulation of genes mainly associated with activation, proliferation, and migration of T and B cells and with MHC class II antigen processing/presentation. Among DHA-modulated genes in GBM, 7.6% showed a significant prognostic relevance. Moreover, a large set of immune-related upstream-regulators (URs) were commonly modulated by DHA in GBM, MM-BM, and MM cells: DHA-activated URs enriched for biological processes mainly involved in the regulation of cytokines and chemokines production, inflammatory response, and in Type I/II/III IFN-mediated signaling; conversely, DHA-inhibited URs were involved in metabolic and proliferative pathways.

CONCLUSIONS

Epigenetic remodeling by guadecitabine represents a promising strategy to increase the efficacy of cancer immunotherapy of GBM, supporting the rationale to develop new epigenetic-based immunotherapeutic approaches for the treatment of this still highly deadly disease.