Aging is often associated with a cognitive decline and a susceptibility to neuronal damage. It is also the most important risk factor for neurodegenerative disorders, particularly Alzheimer’s disease (AD). AD is related to an excess of neurotoxic oligomers of amyloid β peptide (Aβo); however, the molecular mechanisms are still highly controversial. Intracellular Ca²⁺ homeostasis plays an important role in the control of neuronal activity, including neurotransmitter release, synaptic plasticity, and memory storage, as well as neuron cell death. Recent evidence indicates that long-term cultures of rat hippocampal neurons, resembling aged neurons, undergo cell death after treatment with Aβo, whereas short-term cultures, resembling young neurons, do not. These in vitro changes are associated with the remodeling of intracellular Ca²⁺ homeostasis with aging, thus providing a simplistic model for investigating Ca²⁺ remodeling in aging. In vitro aged neurons show increased resting cytosolic Ca²⁺ concentration, enhanced Ca²⁺ store content, and Ca²⁺ release from the endoplasmic reticulum (ER). Ca²⁺ transfer from the endoplasmic reticulum (ER) to mitochondria is also enhanced. Aged neurons also show decreased store-operated Ca²⁺ entry (SOCE), a Ca²⁺ entry pathway related to memory storage. At the molecular level, in vitro remodeling is associated with changes in the expression of Ca²⁺ channels resembling in vivo aging, including changes in N-methyl-D-aspartate NMDA receptor and inositol 1,4,5-trisphosphate (IP₃) receptor isoforms, increased expression of the mitochondrial calcium uniporter (MCU), and decreased expression of Orai1/Stim1, the molecular players involved in SOCE. Additionally, Aβo treatment exacerbates most of the changes observed in aged neurons and enhances susceptibility to cell death. Conversely, the solely effect of Aβo in young neurons is to increase ER–mitochondria colocalization and enhance Ca²⁺ transfer from ER to mitochondria without inducing neuronal damage. We propose that cultured rat hippocampal neurons may be a useful model to investigate Ca²⁺ remodeling in aging and in age-related neurodegenerative disorders.

The molecular basis of amyloid toxicity in Alzheimer’s disease (AD) remains controversial. Amyloid β (Aβ) oligomers promote Ca²⁺ influx, mitochondrial Ca²⁺ overload and apoptosis in hippocampal neurons in vivo and in vitro, but the primary Ca²⁺ entry pathways are unclear. We studied Ca²⁺ entry pathways induced by Aβ oligomers in rat hippocampal and cerebellar neurons. Aβ oligomers induce Ca²⁺ entry in neurons. Ca²⁺ responses to Aβ oligomers are large after synaptic networking and prevented by blockers of synaptic transmission. In contrast, in neurons devoid of synaptic connections, Ca²⁺ responses to Aβ oligomers are small and prevented only by blockers of amyloid channels (NA7) and NMDA receptors (MK801). A combination of NA7 and MK801 nearly abolished Ca²⁺ responses. Non-neuronal cells bearing NMDA receptors showed Ca²⁺ responses to oligomers, whereas cells without NMDA receptors did not exhibit Ca²⁺ responses. The expression of subunits of the NMDA receptor NR1/ NR2A and NR1/NR2B in HEK293 cells lacking endogenous NMDA receptors restored Ca²⁺ responses to NMDA but not to Aβ oligomers. We conclude that Aβ oligomers promote Ca²⁺ entry via amyloid channels and NMDA receptors. This may recruit distant neurons intertwisted by synaptic connections, spreading excitation and recruiting further NMDA receptors and voltage-gated Ca²⁺ channels, leading to excitotoxicity and neuron degeneration in AD.

Colorectal cancer (CRC) is associated with mutations in APC/Wnt leading to c-myc activation and the overexpression of ODC1, the limiting step in polyamine synthesis. CRC cells also display a remodeling of intracellular Ca²⁺ homeostasis that contributes to cancer hallmarks. As polyamines may modulate Ca²⁺ homeostasis during epithelial tissue repair, we investigated whether polyamine synthesis inhibition may reverse Ca²⁺ remodeling in CRC cells and, if so, the molecular basis for this reversal. To this end, we used calcium imaging and transcriptomic analysis in normal and CRC cells treated with DFMO, an ODC1 suicide inhibitor. We found that polyamine synthesis inhibition partially reversed changes in Ca²⁺ homeostasis associated with CRC, including a decrease in resting Ca²⁺ and SOCE along with an increased Ca²⁺ store content. We also found that polyamine synthesis inhibition reversed transcriptomic changes in CRC cells without affecting normal cells. Specifically, DFMO treatment enhanced the transcription of SOCE modulators CRACR2A; ORMDL3; and SEPTINS 6, 7, 8, 9, and 11, whereas it decreased SPCA2, involved in store-independent Orai1 activation. Therefore, DFMO treatment probably decreased store-independent Ca²⁺ entry and enhanced SOCE control. Conversely, DFMO treatment decreased the transcription of the TRP channels TRPC1 and 5, TRPV6, and TRPP1 while increasing TRPP2, thus probably decreasing Ca²⁺ entry through TRP channels. Finally, DFMO treatment enhanced the transcription of the PMCA4 Ca²⁺ pump and mitochondrial channels MCU and VDAC3 for enhanced Ca²⁺ extrusion through the plasma membrane and mitochondria. Collectively, these findings suggested the critical role of polyamines in Ca²⁺ remodeling in colorectal cancer.

Background: Glioblastoma recurrence is driven by diffuse microscopic infiltration beyond the contrast-enhancing tumor margin. GlioMap is an open-access AI model predicting voxelwise infiltration and recurrence risk from multiparametric MRI. This prospective study aimed to validate GlioMap’s biological accuracy and prognostic relevance through histopathological assessment, transcriptomic profiling, and survival analysis within the SupraGlio trial (NCT05735171). Methods: Patients with newly diagnosed glioblastoma underwent neuronavigated biopsies targeting AI-predicted high-risk (HRoR) and low-risk of recurrence (LRoR) regions beyond the contrast-enhancing tumor. Histopathological infiltration served as the ground truth, and transcriptomic profiling characterised each region’s molecular phenotype. Model performance was evaluated using accuracy and area under the receiver operating characteristic curve (AUC). Survival analyses assessed the prognostic value of postoperative HRoR volume. Results: Fifty-eight biopsies from 27 patients were analyzed. GlioMap achieved 0.81 accuracy (95% confidence interval [CI], 0.71-0.91) and 0.84 AUC (95% CI, 0.73-0.93) for histologically confirmed infiltration. Transcriptomic analysis of 48 samples from 16 patients revealed progressive upregulation of invasion- and angiogenesis-related genes (CD44, CHI3L1, STAT3, VEGFA) and downregulation of neuronal markers (MBP, GABRA1) from LRoR to HRoR regions and the tumor core, confirming a neural-to-mesenchymal gradient. Postoperative HRoR volume >1.6 cm³ predicted shorter overall survival (P = .04) and progression-free survival (P = .008). Conclusions: To our knowledge, this study provides the first prospective, biopsy-controlled, molecular validation of an AI model for mapping glioblastoma infiltration. By accurately identifying histologically and transcriptionally infiltrated regions, GlioMap offers a biologically grounded imaging biomarker that could guide extended resection and personalized radiotherapy planning, potentially improving tumor control and patient outcomes.