Imatinib mesylate induces necroptotic cell death and impairs autophagic flux in human cardiac progenitor cells

The receptor tyrosine kinase inhibitor imatinib mesylate has improved patient cancer survival rates but has been linked to long-term cardiotoxicity. This study investigated the effects of imatinib on cell viability, apoptosis, autophagy and necroptosis in human cardiac progenitor cells in vitro. After 24 hours, imatinib significantly reduced cell viability (75.9±2.7% vs. 100.0±0.0%, n=5, p<0.05) at concentrations comparable to peak plasma levels (10 μM). Further investigation showed no increase in caspase 3 or 7 activation. Imatinib also significantly reduced the fluorescence of cells stained with TMRM (74.6±6.5% vs. 100.0±0.0%, n=5, p<0.05), consistent with mitochondrial depolarization. Imatinib increased lysosome and autophagosome content relative to the control, as indicated by changes in acridine orange fluorescence (46.0±5.4% vs. 9.0±3.0, n=7, p<0.001) and expression of LAMP2 (2.4±0.3 fold, n=3, p<0.05) after 24 hours treatment. Although imatinib increased the expression of proteins associated with autophagy, it also impaired the autophagic flux, as demonstrated by the proximity ligation assay staining for LAMP2 (lysosome marker) and LC3II (autophagosome marker), with control cells showing 11.3±2.1 puncta per cell and 48 hours of imatinib treatment reducing the visible puncta to 2.7±0.7 per cell (n=10, p<0.05). Cell viability was partially recovered by autophagosome inhibition by wortmannin, with a 91.8±8.2% (n=5, p>0.05) increase in viability after imatinib and wortmannin co-treatment. Imatinib-induced necroptosis was associated with an 8.5±2.5-fold increase in activation of mixed lineage kinase domain-like pseudokinase. Imatinib-induced toxicity was rescued by RIP1 inhibition relative to the control; 88.6±3.0% vs. 100.0±0.0% (n=4, p>0.05). In summary, imatinib applied to human cardiac progenitor cells depolarizes mitochondria and induces cell death through necroptosis, which can be recovered by inhibition of RIP1, with an additional partial role for autophagy in the cell death pathway. These data provide two possible targets for co-therapies to address imatinib-induced long-term cardiotoxicity.

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Stable Phenotype and Function of Immortalized Lin−Sca-1+ Cardiac Progenitor Cells in Long-Term Culture: A Step Closer to Standardization

Stem Cells and Development ◽

10.1089/scd.2013.0305 ◽

2014 ◽

Vol 23 (9) ◽

pp. 1012-1026 ◽

Cited By ~ 10

Author(s):

Ana G. Freire ◽

Diana S. Nascimento ◽

Giancarlo Forte ◽

Mariana Valente ◽

Tatiana P. Resende ◽

...

Keyword(s):

Progenitor Cells ◽

Cardiac Progenitor Cells ◽

Long Term Culture ◽

And Function

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Tumor necrosis factor-related apoptosis inducing ligand expression and activity in hen granulosa cells

Reproduction ◽

10.1530/rep-06-0287 ◽

2007 ◽

Vol 133 (3) ◽

pp. 609-616 ◽

Cited By ~ 18

Author(s):

A L Johnson ◽

Christine Ratajczak ◽

Morgan J Haugen ◽

Han-Ken Liu ◽

Dori C Woods

Keyword(s):

Cell Death ◽

Tumor Necrosis Factor ◽

Cell Viability ◽

Granulosa Cells ◽

Tumor Necrosis ◽

Caspase 3 ◽

Cell Death Pathway ◽

Wide Range ◽

Trail Signaling ◽

Necrosis Factor

Tumor necrosis factor-related apoptosis inducing ligand (TRAIL) represents one of several cytokine members of the tumor necrosis factor superfamily reported to initiate apoptosis in a wide range of transformed, but not most normal, cell types. The present studies were conducted to evaluate the potential for TRAIL to promote apoptotic cell death in differentiated granulosa cells collected from hen preovulatory follicles. While mRNA encoding critical components (including TRAIL) required for a functional extrinsic cell death pathway are expressed in granulosa cells, TRAIL treatment by itself fails to induce either caspase-3 activity or a decrease in cell viability. On the other hand, preculture of cells with the conventional chemotherapeutic, cisplatin, or the 20S proteosome inhibitor, Z-LLF-CHO, sensitizes granulosa cells to TRAIL as evidenced by enhanced caspase-3 activity after 4 h of culture and loss of cell viability after 24 h when compared with either cisplatin or Z-LLF-CHO treatment alone. Moreover, the sensitizing effect of Z-LLF-CHO on TRAIL-induced loss of cell viability is prevented by the selective caspase-8 inhibitor, Z-IETD-FMK. Interestingly, TRAIL mRNA expression is elevated both in prehierarchal follicles undergoing spontaneous atresia and in prehierarchal follicles induced to undergo atresia for 6 h in vitro. In summary, the data demonstrate the presence of a functional TRAIL signaling pathway in hen granulosa cells, and are consistent with the possibility that TRAIL signaling may directly or indirectly participate in the process of follicle atresia in vivo.

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Latexin Inhibition Mitigates Irradiation Induced Hematopoietic Injury

Blood ◽

10.1182/blood-2018-99-114985 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 2562-2562

Author(s):

Cuiping Zhang ◽

Xiaojing Cui ◽

Ying Liang

Keyword(s):

Bone Marrow ◽

Cell Death ◽

Progenitor Cells ◽

Knockout Mice ◽

Lethal Dose ◽

Negative Regulator ◽

Cell Counts ◽

Survival Pathway ◽

Radiation Induced

Abstract Radiation-associated bone marrow (BM) injury is one of the most serious limiting factors of radiotherapy. Radiation-induced hematopoietic injury, no matter how transient or long lasting, can ultimately impair HSC function and decrease the HSC reserve, leading to increased risk for the development of BM failure or cancer. However, molecular mechanisms underlying radiation-induced HSC functional decline are largely unknown. We previously identified a stem cell regulatory gene, latexin (Lxn), as a novel negative regulator of HSCs in mice. HSCs in Lxn knockout mice (Lxn-/-) had increased self-renewal and survival. In our new findings, we surprisingly found that Lxn-/- mice had the significant survival advantages under lethal dose of total body irradiation (TBI). We further found that HSCs and hematopoietic progenitor cells (HPCs), measured by immunophenotypes and colony assay, recovered much faster in Lxn-/- mice than wild-type mice (WT) within one month after sub-lethal dose of TBI. The better preserved HSC/HPC pool was due to the decreased apoptosis in which the percentage of Annexin V + PI- apoptotic HSCs/HPCs cells was significantly lower in Lxn-/- mice than WT mice. These data suggest that Lxn inactivation protects HSCs and HPCs from radiation-induced cell death, thus mitigating acute hematopoietic suppression and conferring a survival advantage. To determine the long-term effect of TBI on Lxn-/- HSCs, we performed limiting dilution competitive repopulation unit assay (CRU), and found that Lxn-/- CRU was significantly higher than WT CRU. Moreover, we performed serial transplantation experiment, and found that Lxn-/- HSC continuously regenerated blood and bone marrow cells even at the 4th round of transplantation whereas WT HSCs were exhausted. These data provide robust evidence that Lxn inactivation protects functional long-term HSCs from radiation-induced injury. Radiation can increase the risk of hematological malignancy later in the life. We thus maintained a group of mice that were subject to either a single dose of 6.5Gy TBI or split low doses of TBI (2 Gy daily for 6 days), and monitored their gross condition and blood cell counts for 20 months. At 20 month post-radiation, we performed bone marrow analysis and histopathology analysis. We found that Lxn-/- mice did not spontaneously develop hematopoietic malignancies, their bone marrow HSCs/HPCs had normal population size, and bone marrow had normal histopathology. These data suggest that Lxn inactivation mitigates radiation-induced short-term myelosuppression and long-term HSC functional impairment without induction of hematologic malignancy. At the molecular level, we previously reported that Lxn sensitized leukemogenic cells to gamma-irradiation-induced cell-cycle arrest and cell death through Rps3 pathway, and Rps3 was a binding protein of Lxn. Rps3 has been shown to be involved in the NFkB pathway. We found that Rps3 bound Lxn in primary hematopoietic stem and progenitor cells (HSPCs) using Co-IP assay. Lxn-/- HSPCs had the increased expression of Rps3 and NFkB p65 before or post-irradiation. Knockdown of Rps3 in Lxn-/- HSPCs decreased NFkB p65 and increased radiation-induced apoptosis. Moreover, when Lxn-/- HSPCs were treated with NFkB p65 specific inhibitor, the similar phenotypes were also shown, suggesting that Lxn functions through Rps3-NFkB-mediated pro-survival pathway in primary HSPCs. We are currently proving this molecular pathway using the in vivo model by crossing p65 knockout mice with Lxn-/- mice. In conclusion, latexin inhibition mitigates irradiation induced hematopoietic injury via Rps3-NFkB-mediated pro-survival pathway. Disclosures No relevant conflicts of interest to declare.

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Imatinib Mesylate for Patients With Unresectable or Recurrent Gastrointestinal Stromal Tumors: 10-Year Experience From Vietnam

Cancer Control ◽

10.1177/1073274819863776 ◽

2019 ◽

Vol 26 (1) ◽

pp. 107327481986377 ◽

Cited By ~ 2

Author(s):

Kien Do Hung ◽

Quang Le Van ◽

Gia Nguyen Hoang ◽

Phuong Nguyen Thi Bich

Keyword(s):

Imatinib Mesylate ◽

Gastrointestinal Stromal Tumors ◽

Performance Status ◽

Progression Free Survival ◽

High Response Rate ◽

Imatinib Treatment ◽

Middle Income ◽

Stromal Tumors ◽

Asian Patients

Only limited data are available concerning the long-term outcomes of imatinib treatment among Vietnamese or Asian patients with unresectable or recurrent gastrointestinal stromal tumors (GISTs). Our study, which was conducted in 188 patients, aimed to assess the efficacy of imatinib mesylate against unresectable or recurrent GISTs. Imatinib had a high response rate and long survival. Some predictors favorable for progression-free survival and overall survival are good performance status and response with imatinib. Findings are discussed in relation to clinical practice in low- and middle-income country.

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Is three years duration of adjuvant imatinib mesylate treatment sufficient for patients with high-risk gastrointestinal stromal tumor? A study based on long-term follow-up.

Journal of Clinical Oncology ◽

10.1200/jco.2017.35.4_suppl.130 ◽

2017 ◽

Vol 35 (4_suppl) ◽

pp. 130-130

Author(s):

JianXian Lin

Keyword(s):

High Risk ◽

Imatinib Mesylate ◽

Protective Factor ◽

Linear Regression Analysis ◽

R0 Resection ◽

Imatinib Treatment ◽

Long Term Outcomes ◽

Term Survival ◽

Risk Patients

130 Background: The therapy for gastrointestinal stromal tumors (GIST) has changed significantly since the use of Imatinib Mesylate (IM). However, the appropriate duration of receiving adjuvant IM for patients with high-risk GIST who underwent R0 resection is still controversial. Methods: From Jan. 2005 to Dec. 2014, 234 patients who underwent R0 resection and were treated with adjuvant IM were identified from a database. The effect of the medication duration on the long-term outcomes was analyzed. Results: In this study, the 5 year recurrence-free survival (RFS) rate and overall survival (OS) rate in the whole groups were 76.2% and 83.4%, respectively. The patient's prognosis was improved due to the prolongation of the time of receiving the Imatinib treatment (P < 0.05). According to the risk stratification analysis, the survival of the moderate-risk patients who received IM adjuvant therapy for 1 year, 1-3 years and more than 3 years showed improved, but the difference was not statistically significant (P > 0.05). However, in the high-risk patients, the RFS rates of the 1 year group, 1-3 years group, 3-5 years group and more than 5 years group were 36.5%, 68.7%, 71.2% and 90.8%, respectively, and the OS rates were 36.7%,76.6%, 84.0% and 97.4%, respectively (P < 0.001). Additionally, linear regression analysis showed that the long-term outcomes of patients with high-risk GIST significantly improved due to prolonged adjuvant IM treatment durations (P < 0.05). The RFS rate of patients receiving IM more than 5 years was significantly better than those receiving it for less than 5 years. Multivariate analysis in the patients with high-risk GIST showed that tumor located in small intestine was an independent risk factor, while receiving IM treatment was an independent protective factor for prognosis. Conclusions: The long-term outcomes of patients with high risk GIST improved due to the prolongation of the IM treatment. To reduce the recurrence and improve the long-term survival, we suggest that patients with high-risk GIST receive Imatinib treatment for at least 5 years.

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Detection of Autophagy-Related Gene Expression by Conjunctival Impression Cytology in Age-Related Macular Degeneration

Diagnostics ◽

10.3390/diagnostics11020296 ◽

2021 ◽

Vol 11 (2) ◽

pp. 296

Author(s):

Chih-Wen Shu ◽

Youn-Shen Bee ◽

Jiunn-Liang Chen ◽

Chui-Lien Tsen ◽

Wei-Lun Tsai ◽

...

Keyword(s):

Oxidative Stress ◽

Gene Expression ◽

Cell Viability ◽

Retinal Pigment ◽

Age Related Macular Degeneration ◽

Autophagic Flux ◽

Related Gene ◽

Impression Cytology ◽

Conjunctival Impression Cytology

Purpose: To investigate the association of autophagy-related gene expression with age-related macular degeneration (AMD). Methods: Patients with AMD were recruited for analysis by conjunctival impression cytology. mRNA was assessed by real-time polymerase chain reaction (RT-PCR) to evaluate whether the expression of 26 autophagy-related genes (ATGs) was correlated with AMD. Further studies on cell viability and autophagic flux in response to oxidative stress by H2O2 were performed in human retinal pigment epithelial (RPE) cell lines based on the results of impression cytology. Results: Both the neovascular AMD (nAMD) and polypoidal choroidal vasculopathy (PCV) groups had significantly higher mRNA levels of gamma-aminobutyric acid receptor-associated protein-like 1 (GABARAPL1) and microtubule-associated proteins 1A/1B light chain 3B (MAP1LC3B) than the control group, but there was no significant difference between these two groups. Age difference existed only in the AMD group. GABARAPL1 and MAP1LC3B mRNA expression increased significantly after acute oxidative stress in adult retinal pigment epithelial (ARPE-19) cells. Cell viability significantly increased and decreased in the cells harboring GABARAPL1 expression vector and silenced with siRNA against GABARAPL1, respectively, during short-term oxidative stress, whereas viability increased in the GABARAPL1-silenced cells after long-term oxidative stress. Silencing GABARAPL1 itself caused a reduction in autophagic flux under both short and long-term oxidative stress. Conclusion: Our study showed the possibility of assessing autophagy-related gene expression by conjunctival impression cytology. GABARAPL1 was significantly higher in AMD. Although an in vitro study showed an initial protective effect of autophagy, a cell viability study revealed the possibility of a harmful effect after long-term oxidative injury. The underlying mechanism or critical factors require further investigation.

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Abstract 3815: Pim-1 Gene Delivery to Cardiac Progenitor Cells Prevents Long Term Cardiac Failure

Circulation ◽

10.1161/circ.118.suppl_18.s_490 ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Kimberlee Fischer ◽

Weitao Wu ◽

Christopher Cottage ◽

Natalie Gude ◽

Mark Sussman

Keyword(s):

Stem Cell ◽

Progenitor Cells ◽

Left Ventricular ◽

Functional Improvement ◽

Cardiac Progenitor Cells ◽

Intramyocardial Injection ◽

Improved Performance ◽

Enhance Stem Cell ◽

Fractional Shortening

Cardiac stem cell therapy administered at the time of infarction effectively blunts cardiomyopathic damage a few weeks after treatment but long term efficacy of adoptive stem cell transfer remains largely unknown. A comparative analysis shows that long term (25 week) protection is only provided by Pim-1 modified progenitor cells whereas unmodified progenitor cells fail to provide prolonged benefits after six weeks post intramyocardial injection. After infarction mice were intramyocardially injected with saline, unmodified cardiac progenitor cells (CPC’s), or Pim-1 modified CPC’s. At a 12 week time point mice injected with Pim-1 modified CPC’s have increased EF and FS as compared to mice injected with unmodified cells (n=15 for each group). Invasive hemodynamic measurements (n=5 for each group) confirm that mice injected with Pim-1 modified CPC’s had improved performance by assessment of multiple functional criteria compared to unmodified cells. Longitudinal monitoring by echocardiography reveals that mice injected with Pim-1 modified CPC’s sustain fractional shortening and ejection fraction for up to 24 weeks whereas animals that receive unmodified cells begin to fail within 6 weeks after delivery and were not statistically different than saline injected controls after 12 weeks. In addition Pim-1 CPC injected mice had infarct sizes 52% smaller than control groups (p<.02). Both saline and unmodified CPC’s groups maintained similar infarct sizes (~60% of left ventricular free wall). Confocal microscopy reveals engraftment and persistence of injected Pim-1 CPC’s into the myocardium with differentiation into multiple cardiogenic lineages giving rise to myocytes, vasculature, and endothelium Successful long term functional improvement of the heart requires the engraftment of Pim-1 genetically modified cardiac progenitor cells. Unmodified cells offer an acute ameliorative response but ultimately fail in the ability to effectively repair and maintain the function of the heart. These results support use of genetic engineering to enhance stem cell-mediated myocardial regeneration.

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Abstract 217: Long Non-coding RNA Myocardial Infarction-associated Transcript (MIAT) Protects Cardiac Progenitor Cells From Oxidative Stress-induced Cell Death

Circulation Research ◽

10.1161/res.119.suppl_1.217 ◽

2016 ◽

Vol 119 (suppl_1) ◽

Author(s):

Liu Yang ◽

Yang Yu ◽

Baron Arnone ◽

Chan Boriboun ◽

Jiawei Shi ◽

...

Keyword(s):

Oxidative Stress ◽

Myocardial Infarction ◽

Cell Death ◽

Progenitor Cells ◽

Cardiac Cells ◽

Border Zone ◽

Mouse Heart ◽

Cardiac Progenitor Cells

Background: Long non-coding RNAs (lncRNAs) are an emerging class of RNAs with no or limited protein-coding capacity; a few of which have recently been shown to regulate critical biological processes. Myocardial infarction-associated transcript (MIAT) is a conserved mammalian lncRNA, and single nucleotide polymorphisms (SNPs) in 6 loci of this gene have been identified to be strongly associated with the incidence and severity of human myocardial infarction (MI). However, whether and how MIAT impacts on the pathogenesis of MI is unknown. Methods & Results: Quantitative RT-PCR analyses revealed that MIAT is expressed in neonatal mouse heart and to a lesser extent in adult heart. After surgical induction of MI in adult mice, MIAT starts to increase in 2 hours, peaks at 6 hours in atria and 12 hours in ventricles, and decreases to baseline at 24 hours. Fluorescent in situ hybridization (FISH) revealed a slight increase in the number of MIAT-expressing cells in the infarct border zone at 12 hours post-MI. Moreover, qRT-PCR analyses of isolated cardiac cells revealed that MIAT is predominantly expressed in cardiosphere-derived cardiac progenitor cells (CPCs). Treatment of CPCs with H 2 O 2 led to a marked upregulation of MIAT, while knockdown (KD) of MIAT resulted in a significantly impaired cell survival in vitro with H 2 O 2 treatment and in vivo after administered in the ischemic/reperfused heart. Notably, bioinformatics prediction and RNA immunoprecipitation identified FUS (fused in sarcoma) as a novel MIAT-interacting protein. FUS-KD CPCs displayed reduced cell viability and increased apoptosis under oxidative stress. Furthermore, MIAT overexpression enhanced survival of WT CPCs but not FUS-KD CPCs, suggesting that the protective role of MIAT is mediated by FUS. Conclusions: MIAT interacts with FUS to protect CPCs from oxidative stress-induced cell death.

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Bim Is the Critical, and Bad and Bmf Are the Ancillary BH3-Only Proteins for Imatinib Mesylate-Induced Apoptosis of Bcr/Abl-Positive Leukemias.

Blood ◽

10.1182/blood.v106.11.2876.2876 ◽

2005 ◽

Vol 106 (11) ◽

pp. 2876-2876

Author(s):

Junya Kuroda ◽

Hamsa Puthalakath ◽

Philippe Bouillet ◽

Mark S. Cragg ◽

Priscilla N. Kelly ◽

...

Keyword(s):

Cell Death ◽

Imatinib Mesylate ◽

Cell Lines ◽

Cell Killing ◽

Leukemic Cells ◽

Imatinib Treatment ◽

Killing Activity ◽

Induced Apoptosis ◽

Transformed Cell Lines

Abstract Imatinib mesylate (imatinib) exerts the anti-Philadelphia-positive (Ph1+) leukemia activity both by the inhibition of cell proliferation and by the induction of apoptosis. Recent studies demonstrate that the induction of cell death is essential for eradication of Ph1+ leukemic clones in imatinib treatment; however, the molecular mechanisms have not yet been clearly described. By examining the effect of imatinib on parental K562 and subclones overexpressing either Bcl-2, Bcl-XL or a dominant interfering mutant of FADD/MORT1, which blocks death receptor apoptosis signalling, we found that imatinib triggers apoptosis exclusively via the Bcl-2 family-regulated intrinsic apoptotic pathway. We investigated the involvement of BH3-only proteins as apoptotic initiators in imatinib-induced cell death, because the cell life-or-death decision is arbitrated by the balance between pro-apoptotic BH3 only-proteins and anti-apoptotic Bcl-2 proteins. We found that imatinib treatment upregulated Bim in Ph1+ leukemic cell lines and bcr-c-abl transformed murine fetal liver cells (FLCs)-derived cell lines both by transcriptional and post-translational mechanisms. Imatinib also activated Bad through dephosphorylation and upregulated Bmf transcriptionally. To examine the role of Bim in imatinib-induced apoptosis, we examined the cell killing activity of imatinib in subclones of K562 and BV173 Ph1+ cells expressing abnormally reduced levels of Bim using stable RNA interference system. This revealed that the cell killing activity of imatinib largely dependent on Bim expression levels in these cell lines, although significant apoptosis was still evident. To further define the role of Bim, Bad and Bmf in imatinib-induced cell death, we examined the effect of imatinib on retrovirally bcr-c-abl transformed cell lines derived from FLCs from wild type C57BL/6, Bim-/-, Bad-/-, Bim-/-Bad-/- double KO and Bcl-2 transgenic fetuses. The bim-/-bcr-c-abl+ FLCs were shown to be more resistant to imatinib-induced cell death than wt.bcr-c-abl+ FLCs, however, bim-/-bcr-c-abl+ FLCs were eventually induced into cell death, indicating that Bim is not the only initiator of apoptosis. The bad-/-bcr-c-abl+ FLCs were also partially resistant to imatinib-induced cell death. Intriguingly, like in vav.bcl-2.bcr-c-abl+ FLCs, the cell death induction by imatinib (~5.0μM) was largely abrogated in bim-/-bad-/-bcr-c-abl+ FLCs, indicating that Bim collaborates with Bad for the apoptotic induction by imatinib. Importantly, we found that Bim was inducible by ex vivo imatinib treatment in primary Ph1+ leukemic cells only from clinically good responders but not from patients refractory to imatinib treatment. Collectively, these results demonstrate that Bim is the critical but not the only initiator required for imatinib-induced apoptosis of Bcr/Abl-positive hematopoietic cells; Bad and Bmf may be the ancillary BH3-only proteins in this process. Our results provide evidence for the therapeutic significance of regulation of BH3-only proteins, particularly Bim, for the eradication of Ph1+ leukemic cells.

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PXDN reduces autophagic flux in insulin-resistant cardiomyocytes via modulating FoxO1

Cell Death and Disease ◽

10.1038/s41419-021-03699-4 ◽

2021 ◽

Vol 12 (5) ◽

Author(s):

Chan Li ◽

Zhaoya Liu ◽

Qian Xu ◽

Huihui Peng ◽

Jing Cao ◽

...

Keyword(s):

Oxidative Stress ◽

Cell Death ◽

Cell Viability ◽

Essential Role ◽

Degradation Process ◽

Autophagic Flux ◽

Lysosomal Degradation ◽

Akt Phosphorylation ◽

Insulin Resistant ◽

Forkhead Box

AbstractAutophagy, a well-observed intracellular lysosomal degradation process, is particularly important to the cell viability in diabetic cardiomyopathy (DCM). Peroxidasin (PXDN) is a heme-containing peroxidase that augments oxidative stress and plays an essential role in cardiovascular diseases, while whether PXDN contributes to the pathogenesis of DCM remains unknown. Here we reported the suppression of cell viability and autophagic flux, as shown by autophagosomes accumulation and increased expression level of LC3-II and p62 in cultured H9C2 and human AC16 cells that treated with 400 μM palmitate acid (PA) for 24 h. Simultaneously, PXDN protein level increased. Moreover, cell death, autophagosomes accumulation as well as increased p62 expression were suppressed by PXDN silence. In addition, knockdown of PXDN reversed PA-induced downregulated forkhead box-1 (FoxO1) and reduced FoxO1 phosphorylation, whereas did not affect AKT phosphorylation. Not consistent with the effects of si-PXDN, double-silence of PXDN and FoxO1 significantly increased cell death, suppressed autophagic flux and declined the level of FoxO1 and PXDN, while the expression of LC3-II was unchanged under PA stimulation. Furthermore, inhibition of FoxO1 in PA-untreated cells induced cell death, inhibited autophagic flux, and inhibited FoxO1 and PXDN expression. Thus, we come to conclusion that PXDN plays a key role in PA-induced cell death by impairing autophagic flux through inhibiting FoxO1, and FoxO1 may also affect the expression of PXDN. These findings may develop better understanding of potential mechanisms regarding autophagy in insulin-resistant cardiomyocytes.

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