Aurora kinase A/AURKA functionally interacts with the mitochondrial ATP synthase to regulate energy metabolism and cell death

Identification of POU4F1 as a novel prognostic biomarker and therapeutic target in esophageal squamous cell carcinoma

BACKGROUND

Esophageal cancer is a significant global health concern, ranking seventh in incidence and sixth in mortality. It encompasses two pathological types: esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma, with ESCC being more prevalent globally and associated with higher mortality rates. The POU (Pit-Oct-Unc) domain family transcription factors, comprising 15 members, play important roles in embryonic development and organ formation. Aberrant expression of POUs has been observed in several human cancers, influencing cell proliferation, tumor invasion, and drug resistance. However, their specific role in ESCC remains unknown.

METHODS

We analyzed TCGA and GEO databases to assess POUs expression in ESCC tissues. Kaplan-Meier and ROC analyses were used to evaluate the prognostic value of POUs. Gene Set Enrichment Analysis and Protein-Protein interaction network were used to explore the potential pathway. Functional assays (Cell Counting Kit-8, EdU Staining assay, and cloning formation assay) and mechanism analyses (RNA-seq, flow cytometry, and Western blot) were conducted to determine the effects of POU4F1 knockdown on ESCC cell phenotypes and signaling pathways.

RESULTS

POU4F1 and POU6F2 were upregulated in various cancer tissues, including ESCC, compared to normal tissues. POU4F1 expression was significantly correlated with patient survival and superior to previous models (AUC = 0.776). Knockdown of POU4F1 inhibited ESCC cell proliferation and affected cell cycle, autophagy, and DNA damage pathways in ESCC cells.

CONCLUSION

POU4F1 is a novel and promising prognostic and therapeutic target for ESCC patients, providing insights into potential treatment strategies.

Cristae shaping and dynamics in mitochondrial function

Mitochondria are multifunctional organelles of key importance for cell homeostasis. The outer mitochondrial membrane (OMM) envelops the organelle, and the inner mitochondrial membrane (IMM) is folded into invaginations called cristae. As cristae composition and functions depend on the cell type and stress conditions, they recently started to be considered as a dynamic compartment. A number of proteins are known to play a role in cristae architecture, such as OPA1, MIC60, LETM1, the prohibitin (PHB) complex and the F1FO ATP synthase. Furthermore, phospholipids are involved in the maintenance of cristae ultrastructure and dynamics. The use of new technologies, including super-resolution microscopy to visualize cristae dynamics with superior spatiotemporal resolution, as well as high-content techniques and datasets have not only allowed the identification of new cristae proteins but also helped to explore cristae plasticity. However, a number of open questions remain in the field, such as whether cristae-resident proteins are capable of changing localization within mitochondria, or whether mitochondrial proteins can exit mitochondria through export. In this Review, we present the current view on cristae morphology, stability and composition, and address important outstanding issues that might pave the way to future discoveries.

The PIN1-YTHDF1 axis promotes breast tumorigenesis via the m6A-dependent stabilization of AURKA mRNA

The post-transcriptional processing of N6-methyladenosine (m6A)-modified mRNA by YTH domain-containing family protein 1 (YTHDF1) plays a crucial role in the regulation of gene expression. Although YTHDF1 expression is frequently upregulated in breast cancer, the regulatory mechanisms for this remain unclear. In this study, we examined the role of peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (PIN1) in regulating YTHDF1 stability in breast cancer cells. The WW domain of PIN1 interacted with YTHDF1 in a phosphorylation-dependent manner. Additionally, PIN1 overexpression increased YTHDF1 stability by preventing ubiquitin-dependent proteasomal degradation. Furthermore, using the MS2-tagged RNA pull-down assay, we identified Aurora kinase A (AURKA) mRNA as a bona fide substrate of YTHDF1. PIN1-mediated YTHDF1 stabilization increased the stability of AURKA mRNA in an m6A-dependent manner. Furthermore, YTHDF1 knockout reduced AURKA protein expression levels, resulting in anticancer effects in breast cancer cells, including decreased cell proliferation, cell cycle arrest at the G0/G1 phase, apoptotic cell death, and decreased spheroid formation. The anticancer effects induced by YTHDF1 knockout were reversed by AURKA overexpression. Similarly, the knockout of PIN1 produced comparable anticancer effects to those observed in YTHDF1-knockout cells, and these effects were reversed upon overexpression of YTHDF1. In conclusion, the findings of our study suggest that increased YTHDF1 stability induced by PIN1 promotes breast tumorigenesis via the stabilization of AURKA mRNA. Targeting the PIN1/YTHDF1 axis may represent a novel therapeutic strategy for breast cancer.