Regulation of mitochondrial carrier SLC25A13 on breast cancer cell cycle in vitro

Objective·To investigate the role of mitochondrial solute carrier family 25 member 13(SLC25A13)on breast cancer development.Methods·SLC25A13 mRNA and protein expressions in invasive breast cancer tissues and normal breast tissues were from The Cancer Genome Atlas(TCGA)breast cancer dataset.Survival analysis was conducted online by Kaplan-Meier software.MCF-7 cell line was used for in vitro cell assay.Knockdown of SLC25A13 and sirtuin 2(SIRT2)were conducted by siRNA transfection.Cell viability was measured with trypan blue exclusion.Cell cycle arrest was determined by flow cytometry.The mRNA expression of SLC25A13 and P27 were detected by quantitative PCR.The protein level of SLC25A13,P27 and SIRT2 were detected by Western blotting.Protein half-life of P27 was assessed by Western blotting after cycloheximide treatment.Results·SLC25A13 was up-regulated in invasive breast cancer tissues.High expression of SLC25A13 correlated with poor overall survival and breast cancer recurrence.SLC25A13 knockdown inhibited MCF-7 cell cycle progression.P27 and SIRT2 both accumulated after SLC25A13 knockdown.P27 accumulation resulted from prolonged protein half-life.Knockdown of SIRT2 restored cell cycle arrest as well as P27 accumulation caused by SLC25A13 silencing.Conclusion·High expression of SLC25A13 may promote cell cycle progression via SIRT2 in breast cancer development.

Ancient dormant virus remnant ERVW-1 drives ferroptosis via degradation of GPX4 and SLC3A2 in schizophrenia

Human endogenous retroviruses(HERVs)are remnants of retroviral infections in human germline cells from millions of years ago.Among these,ERVW-1(also known as HERV-W-ENV,ERVWE1,or ENVW)encodes the envelope protein of the HERV-W family,which contributes to the pathophysiology of schizophrenia.Additionally,neuropathological studies have revealed cell death and disruption of iron homeostasis in the brains of individuals with schizophrenia.Here,our bioinformatics analysis showed that differentially expressed genes in the human prefrontal cortex RNA microarray dataset(GSE53987)were mainly related to ferroptosis and its associated pathways.Clinical data demonstrated significantly lower expression levels of ferroptosis-related genes,particularly Glutathione peroxidase 4(GPX4)and solute carrier family 3 member 2(SLC3A2),in schizophrenia patients compared to normal controls.Further in-depth analyses revealed a significant negative correlation between ERVW-1 expression and the levels of GPX4/SLC3A2 in schizophrenia.Studies indicated that ERVW-1 increased iron levels,malondialdehyde(MDA),and transferrin receptor protein 1(TFR1)expression while decreasing glutathione(GSH)levels and triggering the loss of mitochondrial membrane potential,suggesting that ERVW-1 can induce ferroptosis.Ongoing research has shown that ERVW-1 reduced the expression of GPX4 and SLC3A2 by inhibiting their promoter activities.Moreover,Ferrostatin-1(Fer-1),the ferroptosis inhibitor,reversed the iron accumulation and mitochondrial membrane potential loss,as well as restored the expressions of ferroptosis markers GSH,MDA,and TFR1 induced by ERVW-1.In conclusion,ERVW-1 could promote ferroptosis by downregulating the expression of GPX4 and SLC3A2,revealing a novel mechanism by which ERVW-1 contributes to neuronal cell death in schizophrenia.

Biological insights in non-small cell lung cancer

Lung oncogenesis relies on intracellular cysteine to overcome oxidative stress.Several tumor types,including non-small cell lung cancer(NSCLC),upregulate the system x-c cystine/glutamate antiporter(xCT)through overexpression of the cystine transporter SLC7A11,thus sustaining intracellular cysteine levels to support glutathione synthesis.Nuclear factor erythroid 2-related factor 2(NRF2)serves as a master regulator of oxidative stress resistance by regulating SLC7A11,whereas Kelch-like ECH-associated protein(KEAP1)acts as a cytoplasmic repressor of the oxidative responsive transcription factor NRF2.Mutations in KEAP1/NRF2 and p53 induce SLC7A11 activation in NSCLC.Extracellular cystine is crucial in supplying the intracellular cysteine levels necessary to combat oxidative stress.Disruptions in cystine availability lead to iron-dependent lipid peroxidation,thus resulting in a type of cell death called ferroptosis.Pharmacologic inhibitors of xCT(either SLC7A11 or GPX4)induce ferroptosis of NSCLC cells and other tumor types.When cystine uptake is impaired,the intracellular cysteine pool can be sustained by the transsulfuration pathway,which is catalyzed by cystathionine-B-synthase(CBS)and cystathionine g-lyase(CSE).The involvement of exogenous cysteine/cystine and the transsulfuration pathway in the cysteine pool and downstream metabolites results in compromised CD8^(+)T cell function and evasion of immunotherapy,diminishing immune response and potentially reducing the effectiveness of immunotherapeutic interventions.Pyroptosis is a previously unrecognized form of regulated cell death.In NSCLCs driven by EGFR,ALK,or KRAS,selective inhibitors induce pyroptotic cell death as well as apoptosis.After targeted therapy,the mitochondrial intrinsic apoptotic pathway is activated,thus leading to the cleavage and activation of caspase-3.Consequently,gasdermin E is activated,thus leading to permeabilization of the cytoplasmic membrane and cell-lytic pyroptosis(indicated by characteristic cell membrane ballooning).Breakthroughs in KRAS G12C allele-specific inhibitors and potential mechanisms of resistance are also discussed herein.