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Prohibitin (PHB) is a highly conserved, ubiquitously expressed, multifunctional protein with a well-characterized function as a chaperone-stabilizing mitochondrial proteins. Recently it was reported that nuclear PHB participates in HIRA chaperone complexes and regulates downstream gene expression via cell cycle independent deposition of H3.3 into DNA. However, the role of PHB in cancer progression remains controversial with conflicting reports in the literature, perhaps due to its cell type-dependent subcellular localization. Here, we report that the increased expression of nuclear PHB is positively correlated with metastasis of breast cancer cell lines. We showed PHB participates in the HIRA complex by interacting with HIRA through the linker region of the PHB domain and stabilizes all components of the HIRA complex in breast cancer. Overexpression of nuclear PHB resulted in a higher enrichment of histone H3.3 deposited by the HIRA complex at the promoters of mesenchymal markers. This coincided with an increased gene expression level of these markers, and induced EMT in breast cancer. Overall, these molecular and structural mechanisms suggest that nuclear PHB could hold promise as a potential target for cancer therapy., (© 2020 The Authors. Published by FEBS Press and John Wiley & Sons Ltd.)

Background: A polymorphic variant allele (T-allele) in the 3'-UTR of prohibitin (C-to-T at nucleotide 729) was reported to be associated with an increased risk of breast cancer. However, the association between the 3'-UTR polymorphism of prohibitin and the susceptibility to gastric cancer remains unknown. Thus, we investigated the distribution of prohibitin genotypes in Chinese patients with gastric cancer and subsequently analyzed the association between the 3'-UTR polymorphism of prohibitin and the risk of gastric cancer in that population., Methods: The distribution of 3'-UTR polymorphism of prohibitin in 82 gastric cancer patients was determined by sequencing and compared with that of 171 healthy controls. Luciferase reporter assay was used to investigate the effect of 3'-UTRs variant on PHB expression., Results: Our study discovered two major polymorphic sites in the 3'-UTR of prohibitin (C-to-T at nucleotide 729 and G to A at nucleotide 758). The C/T polymorphism at 729 site was not associated with the increased risk of gastric cancer (P=.961, OR=1.044, 95%CI: 0.187-5.818); however, G/A polymorphism at nucleotide 758 increased the risk of gastric cancer (P=.017, OR=1.923, 95%CI: 1.119-3.305). Luciferase reporter constructs containing the 758A allele showed higher luciferase activity compared with the wild-type allele, which indicated that 758 G>A in 3'-UTR increased PHB expression., Conclusions: The G to A transition but not the C-to-T transition in the 3'-UTR of prohibitin was associated with an increased risk of gastric cancer in Chinese population., (© 2017 Wiley Periodicals, Inc.)