PHLDA1 (pleckstrin homology-like domain, family A, member 1) is a multifunctional protein involved in pathophysiological conditions such as cancer. Our previous research revealed changes in the proteome of PHLDA1-silenced human neuroblastoma IMR-32 cells. One of the proteins that was increased in PHLDA1-silenced cells was the efflux pump ABCB1 (ATP binding cassette subfamily B member 1). In this study, ABCB1 efflux pump upregulation in PHLDA1-silenced IMR-32 cells led to increased resistance of the cells to xenobiotic agents. Experiments revealed that xenograft tumors grown in immunocompromised mice from PHLDA1-silenced cells presented multiple changes in comparison with tumors grown from control cells. Tumors grown from PHLDA1-silenced cells were larger and contained fewer apoptotic cells than control tumors. The blood vessels within the tumors grown from PHLDA1-silenced cells displayed increased extravasation and the extracellular matrix of the tumors presented increased collagen content in comparison to that of the control tumors. The results showed that silencing PHLDA1 in vivo promoted human neuroblastoma cell survival, decreased the apoptotic potential of the cells, disrupted angiogenesis in developing tumors, and altered collagen network formation.
© 2025. The Author(s).

The membranous ER spans the entire cell, creating a network for the biosynthesis of proteins and lipids, cell-wide communication, and nuclear delivery of molecules, including therapeutic agents. Here, we identify a novel ER response triggered by the tumoricidal complex alpha1-oleate, defined by a loss of peripheral ER structure, extensive ER vesiculation. Alpha1-oleate was present in the ER-derived vesicle membranes, also decorated by ER-resident and ER-interacting proteins, calnexin and ORP3, and in their lumen, also enriched for KDEL, confirming their ER origin distinct from lipid droplets. Rapid nuclear uptake of the complex constituents resulted in diffuse nuclear staining, and the asymmetrical perinuclear enrichment of the collapsing ER with its content of alpha1-oleate created large invaginations lined by the ER, inner nuclear membrane markers, and lamin nucleoskeleton. In parallel, a change in nuclear shape resulted in a volcano-like structure. This newly discovered, potent ER response to alpha1-oleate may have evolved to package ER-associated cellular contents in the nuclei of dying tumor cells, thus sequestering toxic cell debris associated with apoptotic cell death.
© 2025 Sabari et al.

Identifying specific inhibitors of the MYC oncogene has been challenging, due to off target effects associated with MYC inhibition. This study investigated how the recombinant Escherichia coli Lon protease (rLon), which targets MYC in human cells, inhibits MYC over-activation in models of infection and cancer. In silico predictions identified specific peptide domains of bacterial Lon that target MYC and the affinity of these peptides for MYC was investigated by surface plasmon resonance. The N-terminal domain of rLon was shown to interact with the C-terminal, leucine zipper domain of MYC and MAX and to prevent MYC/MAX dimerization. Furthermore, rLon targeted and degraded c-MYC in vitro and in cellular models, through the peptidase domain. In a model of kidney infection, rLon treatment prevented, c-MYC, N-MYC and L-MYC over-expression, MYC-dependent gene expression, specifically renal toxicity genes and pathology, suggesting that rLon recognizes and corrects MYC dysregulation in this disease. The findings describe a multitarget mechanism of MYC inhibition by rLon, and the combined effects achieved by the Lon domains, targeting different MYC epitopes and MYC-dependent functions, with no evidence of toxicity or detrimental effects on homeostatic MYC expression.
© 2025. The Author(s).

Living systems depend on continuous energy input for growth, replication and information processing. Cells use membrane proteins as nanomachines to convert light or chemical energy of nutrients into other forms of energy, such as ion gradients or adenosine triphosphate (ATP). However, engineering sustained fuel supply and metabolic energy conversion in synthetic systems is challenging. Here, inspired by endosymbionts that rely on the host cell for their nutrients, we introduce the concept of cross-feeding to exchange ATP and ADP between lipid-based compartments hundreds of nanometres in size. One population of vesicles enzymatically produces ATP in the mM concentration range and exports it. A second population of vesicles takes up this ATP to fuel internal reactions. The produced ADP feeds back to the first vesicles, and ATP-dependent reactions can be fuelled sustainably for up to at least 24 h. The vesicles are a platform technology to fuel ATP-dependent processes in a sustained fashion, with potential applications in synthetic cells and nanoreactors. Fundamentally, the vesicles enable studying non-equilibrium processes in an energy-controlled environment and promote the development and understanding of constructing life-like metabolic systems on the nanoscale.
© 2024. The Author(s).

Neuroblastoma (NB) is the most common extracranial pediatric solid tumor originating from the abnormal development of cells of the sympathoadrenal lineage of the neural crest. Targeting GD2 ganglioside (GD2), a glycolipid expressed on neuroblastoma cells, with GD2 ganglioside-recognizing antibodies affects several pivotal signaling routes that drive or influence the malignant phenotype of the cells. Previously performed gene expression profiling helped us to identify the PHLDA1 (pleckstrin homology-like domain family A member 1) gene as the most upregulated gene in the IMR-32 human neuroblastoma cells treated with the mouse 14G2a monoclonal antibody. Mass spectrometry-based proteomic analyses were applied to better characterize a role of PHLDA1 protein in the response of neuroblastoma cells to chimeric ch14.18/CHO antibody. Additionally, global protein expression profile analysis in the IMR-32 cell line with PHLDA1 silencing revealed the increase in biological functions of mitochondria, accompanied by differentiation-like phenotype of the cells. Moreover, mass spectrometry analysis of the proteins co-immunoprecipitated using anti-PHLDA1-specific antibody, selected a group of possible PHLDA1 binding partners. Also, a more detailed analysis suggested that PHLDA1 interacts with the DCAF7/AUTS2 complex, a key component of neuronal differentiation in vitro. Importantly, our results indicate that PHLDA1 silencing enhances the EGF receptor signaling pathway and combinatory treatment of gefitinib and ch14.18/CHO antibodies might be beneficial for neuroblastoma patients. Data are available via ProteomeXchange with the identifier PXD044319.
Copyright © 2024 Bugara, Durbas, Kudrycka, Malinowska, Horwacik and Rokita.