Biology subjects

Perumal, N.

Publications and source records attributed to Perumal, N..

4 recordsLinked to original sources

bioRxiv2022

MiR-1253 Potentiates Cisplatin Response in Pediatric Group 3 Medulloblastoma by Regulating Ferroptosis

Medulloblastomas (MB) are the most common malignant pediatric brain tumor and a leading cause of childhood mortality. Aggressive tumors belonging to group 3 (G3MB) are distinguished by a marked reduction in programmed cell death by ferroptosis. These aggressive tumors also enrich iron transport and glutathione metabolism. A highly enriched pathway in these tumors is iron-sulfur (Fe-S) cluster binding corresponding to significant upregulation of ABCB7, a poor prognostic feature linked with accelerated mortality. This study elucidated whether repressing ABCB7 activates ferroptosis to mitigate G3MB aggressiveness and whether this pathway is pharmacologically targetable. In silico and in vitro analyses confirmed upregulation of ABCB7 and GPX4, the central regulator of ferroptosis, in G3MB cell lines and tumors. Repressing ABCB7 (miR-1253OE, siABCB7, sh-ABCB7) induced iron overload, elicited oxidative stress, and triggered lipid peroxidation, leading to an abrogation of medullosphere formation and cell death by ferroptosis. Intriguingly, fractionation studies revealed that ABCB7 repression abrogated GPX4 expression, most likely by GSH depletion. Repressing ABCB7 induced mitochondrial dysfunction and reduced oxidative phosphorylation. Cisplatin, a chemotherapeutic mainstay of G3MB, induces cell death by DNA crosslinking. In ABCB7 repressed cell lines, the IC50 of cisplatin was halved, resulting in augmented oxidative stress and lipid peroxidation, culminating in a higher index of ferroptosis. Artesunate, an anti-malarial drug capable of triggering ferroptosis, was shown to synergize with cisplatin, reducing tumor burden and significantly prolonging survival. Taken together, the current study illustrates how targeting iron transport can augment ferroptosis in G3MBs. It further identifies an FDA-approved drug capable of recapitulating these effects and potentiating mainstay chemotherapy.

cancer biology↗

bioRxiv2021

MiR-212-3p functions as a tumor suppressor gene in group 3 medulloblastoma via targeting Nuclear Factor I/B (NFIB)

BackgroundMedulloblastoma (MB), the most frequent malignant pediatric brain tumor, is subdivided into four primary subgroups, wingless-type (WNT), sonic hedgehog (SHH), group 3, and group 4. Haploinsufficiency of chromosome 17p13.3 and c-Myc amplification distinguish high-risk group 3 tumors associated with rapid metastasis, recurrence and early mortality. We sought to identify the role of miR-212-3p, which resides on chromosome 17p13.3, in the pathophysiology of group 3 MB. MethodsWe first determined miR-212-3p expression in group 3 MB using several publicly-available datasets with confirmatory studies in vitro. We then identified epigenetic regulation by studying methylation and HDAC modifications along the promoter region. We used two systems for expression restoration, i.e. transient transfection or stable induction, to delineate miR-212-3ps tumor suppressive and biochemical properties via assays assessing cancer proliferation, migration, invasion, colony formation, along with cell cycle and apoptosis analyses. We then compared MB and miR target databases to isolate a putative target whose biochemical and oncogenic properties were similarly elucidated using either transient silencing of target expression or stable induction of miR-212-3p. ResultsRNA expression analyses revealed dramatically reduced miR-212-3p levels in group 3 tumors and cell lines mainly through epigenetic silencing via histone modifications. Restoring miR-212-3p expression reduced in vitro cancer cell proliferation, migration, colony formation, and wound healing. Elevated miR-212-3p levels shifted c-Myc phosphorylation (from serine-62 to threonine-58), triggering destabilization and degradation; concurrently, its pro-apoptotic binding partners, i.e., Bin-1 and P19ARF, were upregulated with subsequent elevated apoptotic signals. Using a combination of transcriptomic data and dual luciferase assay, we isolated an oncogenic target of miR-212-3p, i.e. NFIB, a nuclear transcription factor implicated in metastasis and recurrence in various cancers. Increased expression of NFIB was confirmed in group 3 tumors, with poor survival shown in high-expressing patients. Transient NFIB silencing in vitro reduced cancer cell proliferation, colony formation, migration, and invasion. Concurrently, in group 3 MB cells, reduced medullosphere formation along with decreased expression of stem cell markers (Nanog, Oct4, Sox2, CD133) were noted. ConclusionThese results substantiate the tumor-suppressive role of miR-212-3p in group 3 MB and provide a potential therapeutic oncogenic target implicated in metastasis and tumor recurrence.

cancer biology↗

bioRxiv2020

Longitudinal cerebrospinal fluid proteome profiling of acute and sustained antidepressant-like effects of (2R,6R)-hydroxynorketamine (HNK) reveals involvement of glucocorticoid receptor signaling

Delayed onset of antidepressant action is a shortcoming in depression treatment. Ketamine and its metabolite (2R,6R)-hydroxynorketamine (HNK) have emerged as promising rapidacting antidepressants. However, their mechanism of action remains unknown. In this study, we first described the anxious and depression-prone inbred mouse strain, DBA/2J, as a animal model to assess the antidepressant-like effects of ketamine and HNK in vivo. To decode the molecular mechanisms mediating HNKs rapid antidepressant effects, a longitudinal cerebrospinal fluid (CSF) proteome profiling of its acute and sustained effects was conducted using an unbiased, hypothesis-free mass spectrometry-based proteomics approach. A total of 387 proteins were identified, with a major implication of significantly differentially expressed proteins in the glucocorticoid receptor (GR) signaling pathway, providing evidence for a link between HNK and regulation of the stress hormone system. Mechanistically, we identified HNK to repress GR-mediated transcription and reduce hormonal sensitivity of GR in vitro. In addition, mammalian target of rapamycin (mTOR) and brain-derived neurotrophic factor (BDNF) were predicted to be important upstream regulators of HNK treatment. Our results contribute to precise understanding of the temporal dynamics and molecular targets underlying HNKs rapid antidepressant-like effects, which can be used as a benchmark for improved treatment strategies for depression in future.

neuroscience↗

bioRxiv2019

Enhanced autophagic-lysosomal activity and increased BAG3-mediated selective macroautophagy as adaptive response of neuronal cells to chronic oxidative stress

Oxidative stress and a disturbed cellular protein homeostasis (proteostasis) belong to the most important hallmarks of aging and of neurodegenerative disorders. The proteasomal and autophagic-lysosomal degradation pathways are key measures to maintain proteostasis. Here, we report that hippocampal cells selected for full adaptation and resistance to oxidative stress induced by hydrogen peroxide (oxidative stress-resistant cells, OxSR cells) showed a massive increase in the expression of components of the cellular autophagic-lysosomal network and a significantly higher overall autophagic activity. A comparative expression analysis revealed that distinct key regulators of autophagy are upregulated in OxSR cells. The observed adaptive autophagic response was found to be independent of the upstream autophagy regulator mTOR but is accompanied by a significant upregulation of further downstream components of the canonical autophagy network such as Beclin1, WIPI1 and the transmembrane ATG9 proteins. Interestingly, the expression of the HSP70 co-chaperone BAG3, mediator of BAG3-mediated selective macroautophagy and highly relevant for the clearance of aggregated proteins in cells was found to be increased in OxSR cells that were consequently able to effectively overcome proteotoxic stress. Overexpression of BAG3 in oxidative stress-sensitive HT22 wildtype cells partly established the vesicular phenotype and the enhanced autophagic flux seen in OxSR cells suggesting that BAG3 takes over a key part in the adaptation process. A full proteome analysis demonstrated additional changes in the expression of mitochondrial proteins, metabolic enzymes and different pathway regulators in OxSR cells as consequence of the adaptation to oxidative stress in addition to autophagy-related proteins. Taken together, this analysis revealed a wide variety of pathways and players that act as adaptive response to chronic redox stress in neuronal cells.

cell biology↗