Novel pentacyclic derivatives and benzylidenes of the progesterone series cause anti-estrogenic and antiproliferative effects and induce apoptosis in breast cancer cells

Cancer-Specific Activation of the Vesicular Stomatitis Virus Matrix by Survivin Promoter in Breast Cancer Cells

Oncolytic viral-based therapy and specific gene expression by promoters are modern targeted oncotherapy approaches that have gained significant attention in recent years. In this study, both strategies were combined by designing cancer-specific activation of vesicular stomatitis virus matrix expression under the survivin promoter. The matrix sequence was cloned downstream of the survivin promoter (pM). After transfecting MCF-7 cells with pM, cell proliferation and apoptosis induction were assessed. Additionally, the transcript levels of matrix and apoptosis-related genes in response to pM was assessed. The proliferation of MCF-7 cells was significantly reduced by the constructed matrix-expressing plasmid at 48 and 72 h post-transfection (p < 0.05). Enhanced matrix expression resulted in the down-regulation of MMP-9, TP53, and NF-kB, while simultaneously up-regulating Bax transcripts. Evaluating the effect of pM vector on apoptosis induction revealed a significant increase in the MCF-7 cells compared to untreated cells (p < 0.05). The absence of significant matrix gene expression in HDF cells, relative to MCF-7 cells, further underscores the specific function of the Survivin promoter in cancer cells. These findings suggest that the matrix may have various biological functions in a diverse set of non-apoptotic pathways. Further research on the association of the matrix with other genes could provide insights into the biomedical significance and future perspectives of the matrix in cancer gene therapy.

Apoptotic and Molecular Mechanisms of Carthamidin in Breast Cancer Therapy: An Integrated In Vitro and In Silico Study

The current study examines the anticancer properties of the chemical carthamidin in breast cancer through in-vitro and in silico analysis. This study's results demonstrated that carthamidin strongly inhibited the proliferation of MCF 7 cells in vitro, as evidenced by an IC50 value of 128.65 µg/mL at 24 h, determined using the MTT test. Laser confocal microscopy utilizing AO/EB labeling validated apoptotic effects through upregulating pro-apoptotic cell markers. At the same time, the ROS assay demonstrated elevated ROS production in the treated cells. LDH leakage was corroborated by leakage analysis, revealing high LDH levels at 100 µg/mL. The cellular growth parameters were subsequently examined via flow cytometry, showing that the cell cycle was halted in the G0/G1 phase, with 82.9% of the cells residing there. The molecular docking research demonstrated that carthamidin displayed a significant binding affinity with Notch receptors - NOTCH 1-4 and p53, with binding scores ranging from - 5.027 to - 7.402 kcal/mol. The results suggest that carthamidin has therapeutic potential in inducing apoptosis and impairing cancer cells, warranting further investigation in breast cancer treatments.

CLDN11 deficiency upregulates FOXM1 to facilitate breast tumor progression through hedgehog signaling pathway

Claudins (CLDNs) play a crucial role in regulating the permeability of epithelial barriers and can impact tumor behavior through alterations in their expression. However, the precise mechanisms underlying the involvement of CLDNs in breast cancer progression remain unclear. This study aimed to investigate the role of CLDN11 in breast cancer progression. Utilizing the TCGA database and clinical specimens from breast cancer patients, we observed reduced expression of CLDN11 in tumor tissues, which correlated with poor prognosis in breast cancer patients. In vitro, silencing of CLDN11 enhanced the proliferative and migratory characteristics of breast cancer cell lines MCF-7 and MDA-MB-231. Mechanistically, CLDN11 deficiency promoted the upregulation of Forkhead Box M1 (FOXM1) by activating the hedgehog signaling pathway, thereby sustaining tumor progression in breast cancer. In vivo, blockade of hedgehog signaling suppressed the tumor progression induced by CLDN11 silencing. Our study highlights the significance of the CLDN11/FOXM1 axis in breast cancer progression, suggesting CLDN11 as a potential diagnostic indicator and therapeutic target for clinical therapy.

Photochemical Metal-Free synthesis and biological Assessment of isocryptolepine analogues targeting estrogen receptor Alpha in breast cancer cells

The aim of this study was to develop a new series of isocryptolepines and evaluate their antiproliferative and antiestrogenic activities on cancer cells. A series of isocryptolepine derivatives were synthesized using developed one-pot photochemical, metal-free protocol, employing readily available 2-arylindoles as starting compounds. The resulting isocryptolepines demonstrated (sub)micromolar inhibitory activity against selected breast cancer cell lines. The IC50 values ​​of lead compound 3c against hormone-dependent breast cancer types (MCF7 and T47D) were 0.3 μM and 0.12 μM, respectively, and significantly greater than 3 μM against estrogen receptor α (ERα)-deficient cell lines, MDA-MB-231 and HCC1954, respectively. To assess the antiestrogenic potency of compound 3c, MCF7 cells were transfected with a plasmid containing a luciferase reporter gene under the control of an estrogen-responsive element (ERE), creating the MCF7/ERE-LUC cell subline. In these cells, luciferase activity was induced by the natural ERα ligand, 17β-estradiol (E2). Compound 3c inhibited luciferase activity by 50 % at a concentration of 0.12 μM, highlighting its potent inhibitory effect on ERα. Molecular modeling further indicated that compound 3c could directly bind to ERα. Compound 3c induced apoptosis, as evidenced by PARP cleavage and downregulation of p-Bcl-2 and Bcl-2, and demonstrated synergistic effects in combination with the chemotherapeutic agent 5-fluorouracil. Compound 3c also showed selectivity towards hormone-dependent breast cancer cells, likely targeting ERα - a key driver in this cancer subtype. In summary, we report the development of a first-in-class antiestrogenic isocryptolepine with notable pro-apoptotic efficacy.

Antitumor progestins activity: Cytostatic effect and immune response

Progestins are used to treat some hormone-sensitive tumors. This review discusses the mechanisms of progestins' effects on tumor cells, the differences in the effects of progesterone and its analogs on different tumor types, and the influence of progestins on the antitumor immune response. Progestins cause a cytostatic effect, but at the same time they can suppress the antitumor immune response, and this can promote the proliferation and metastasis of tumor cells. Such progestins as dienogest, megestrol acetate and levonorgestrel increase the activity of NK-cells, which play a major role in the body's fight against tumor cells. The use of existing progestins and the development of new drugs with gestagenic activity may hold promise in oncotherapy.

Obtusifolin inhibits podocyte apoptosis by inactivating NF-κB signaling in acute kidney injury

Acute kidney injury (AKI) is a common clinical condition and is associated with unacceptable morbidity and mortality. Obtusifolin is an anthraquinone extracted from the seeds of Cassia obtusifolia with anti-inflammatory properties. This study focused on the role and mechanism of obtusifolin in AKI. The mouse podocyte cell line MPC5 was exposed to lipopolysaccharide (LPS) to establish a cell model of AKI. The viability of MPC5 cells treated with obtusifolin and/or LPS was detected by 3-(4, 5-Dimethylthiazol-2-yl)-2,5diphenyltetrazolium bromide assay. Cell apoptosis was analyzed by flow cytometry. The levels of podocyte injury- and apoptosis-related proteins as well as the nuclear factor-kappaB (NF-κB) signaling pathway was examined using western blotting analysis. The renal protective effects of obtusifolin were determined using an LPS-induced mouse model of AKI. Serum creatinine and blood urea nitrogen levels were measured. Hematoxylin-eosin staining of kidney sections was performed to evaluate renal histology. We found that MPC5 cells treated with LPS showed suppressed cell viability (p < 0.01) and increased cell apoptosis (p < 0.001). LPS reduced the protein expression of Bcl-2, nephrin, and synaptopodin as well as increased the protein levels of Bax and Cleaved Caspase-3 in podocytes in a concentration-dependent manner (p < 0.01). In addition, 10 μg/ml LPS-repressed cell viability was rescued by obtusifolin in a concentration-dependent manner (p < 0.01). Moreover, LPS-induced increase in MPC5 cell apoptosis was reversed by obtusifolin treatment (p < 0.01). Obtusifolin administration ameliorated LPS-induced kidney injury and reduced blood urea nitrogen and serum creatinine levels in mice (p < 0.001). Additionally, obtusifolin inhibited LPS-induced activation of NF-κB signaling in vitro and in vivo (p < 0.01). Overall, obtusifolin was effective in protecting renal function against LPS-induced AKI via inactivation of NF-κB signaling, which suggested that obtusifolin may act as a valuable agent for AKI therapy.

Succinylation of 14-3-3 theta by CPT1A promotes survival and paclitaxel resistance in nasal type extranodal natural killer/T-cell lymphoma

BACKGROUND

The aggressive and refractory extranodal natural killer/T-cell lymphoma, nasal type (ENKTL-NT) is a subtype of non-Hodgkin's lymphoma. Succinylation promotes progression in a variety of tumors, but its mechanism in ENKTL-NT is unclear.

METHODS

Bioinformatic analysis was performed to screen differentially expressed genes in the ENKTL dataset. Cell transfection techniques were used for knockdown and overexpression of genes. The mRNA and protein expression were detected using RT-qPCR and western blot, respectively. Immunohistochemical staining was used to assess protein expression in situ. For the detection of cell proliferation activity, CCK-8, clonal formation, and EDU staining assays were used. Flow cytometry was employed to detect apoptosis. Co-immunoprecipitation was utilized for the identification of protein interactions and succinylation modifications.

RESULTS

Succinyltransferase CPT1A was highly elevated in ENKTL-NT and was associated with a dismal prognosis. CPT1A knockdown suppressed SNK-6 cells' proliferation and induced apoptosis, while these effects were reversed by the overexpression of 14-3-3theta. Co-immunoprecipitation results showed that CPT1A caused succinylation of 14-3-3theta at site of K85, thereby enhancing the protein stability. Suppression of CPT1A-induced succinylation of 14-3-3theta by ST1326 resulted in the inhibition of SNK-6 cell proliferation and increased apoptosis. Paclitaxel combined with knockdown of CPT1A significantly inhibited the proliferation of ENKTL-NT compared to paclitaxel alone.

CONCLUSION

CPT1A induces succinylation of 14-3-3theta at the K85 site, promoting ENKTL-NT proliferation. The anti-ENKTL activity of paclitaxel was improved when combined with CPT1A knockdown.

Role of C/EBP Homologous Protein (CHOP) and Nupr1 Interaction in Endoplasmic Reticulum Stress-Induced Apoptosis of Lens Epithelial Cells

Our study mainly analyzed the mechanism of C/EBP homologous protein (CHOP) and its interacting protein Nupr1 on endoplasmic reticulum stress (ERS) induced lens epithelial cells (LEC) apoptosis. Cell proliferation was detected by CCK-8. Apoptosis was detected by flow cytometry and TUNEL. Nupr1 expression was detected by RT-qPCR. The expressions of CHOP, Nupr1, apoptosis-related protein, and ERS-related protein were detected by Western blot. DCFH-DA probe was used to detect cell ROS. The SOD, GSH-PX, and MDA contents were detected by the kit. Co-IP was used to detect the interaction between CHOP and Nupr1. The morphology of the lens was detected by HE staining. The result shows that Tunicamycin (TU) can induce endoplasmic reticulum stress and apoptosis in LEC in a concentration-dependent manner. TU induction leads to the occurrence of CHOP nuclear translocation. Overexpression of CHOP can further enhance the inhibitory effect of TU on LEC proliferation and the promotion of apoptosis, while knockdown of CHOP has the opposite effect. CHOP and Nupr1 are interacting proteins, and knockdown of Nupr1 or addition of Nupr1 inhibitor ZZW-115 can reverse the effects of TU and overexpression of CHOP, respectively. It has been observed in animal experiments that treatment with oe-CHOP can further aggravate the pathological lesions of the rat lens, while ZZW-115 can reverse the effect of oe-CHOP to a certain extent and improve the lesions of the rat lens. Overall, CHOP interacts with Nupr1 to regulate apoptosis caused by ERS and mediate cataract progression in rats, and this study provides a new potential therapeutic target for the treatment of cataract.

Rapamycin inhibits B16 melanoma cell viability invitro and invivo by inducing autophagy and inhibiting the mTOR/p70‑S6k pathway

Rapamycin is an immunosuppressant that has been shown to prevent tumor growth following organ transplantation. However, its exact mode of antitumor action remains unknown. The present study used the B16-F10 (B16) murine melanoma model to explore the antitumor mechanism of rapamycin, and it was revealed that rapamycin reduced B16 cell viability in vitro and in vivo. In addition, in vitro and in vivo, the results of western blotting showed that rapamycin reduced Bcl2 expression, and enhanced the protein expression levels of cleaved caspase 3 and Bax, indicating that it can induce the apoptosis of B16 melanoma cells. Furthermore, the results of cell cycle analysis and western blotting showed that rapamycin induced B16 cell cycle arrest in the G1 phase, based on the reduction in the protein expression levels of CDK1, cyclin D1 and CDK4, as well as the increase in the percentage of cells in G1 phase. Rapamycin also significantly increased the number of autophagosomes in B16 melanoma cells, as determined by transmission electron microscopy. Furthermore, the results of RT-qPCR and western blotting showed that rapamycin upregulated the protein expression levels of microtubule-associated protein light chain 3 (LC3) and Beclin-1, while downregulating the expression of p62 in vitro and in vivo, thus indicating that rapamycin could trigger cellular autophagy. The present study revealed that rapamycin in combination with chloroquine (CQ) further increased LC3 expression compared with that in the CQ group, suggesting that rapamycin induced an increase in autophagy in B16 cells. Furthermore, the results of western blotting showed that rapamycin blocked the phosphorylation of p70 ribosomal S6 kinase (p70-S6k) and mammalian target of rapamycin (mTOR) proteins in vitro and in vivo, thus suggesting that rapamycin may exert its antitumor effect by inhibiting the phosphorylation of the mTOR/p70-S6k pathway. In conclusion, rapamycin may inhibit tumor growth by inducing cellular G1 phase arrest and apoptosis. In addition, rapamycin may exert its antitumor effects by inducing the autophagy of B16 melanoma cells in vitro and in vivo, and the mTOR/p70-S6k signaling pathway may be involved in this process.

Doxazosin inhibits vasculogenic mimicry in human non‑small cell lung cancer through inhibition of the VEGF‑A/VE‑cadherin/mTOR/MMP pathway

Lung cancer is the leading cause of cancer-related death worldwide, and ~85% of lung cancers are non-small cell lung cancer (NSCLC), which has a low 5-year overall survival rate and high mortality. Several therapeutic strategies have been developed, such as targeted therapy, immuno-oncotherapy and combination therapy. However, the low survival rate indicates the urgent need for new NSCLC treatments. Vasculogenic mimicry (VM) is an endothelial cell-free tumor blood supply system of aggressive and metastatic tumor cells present during tumor neovascularization. VM is clinically responsible for tumor metastasis and resistance, and is correlated with poor prognosis in NSCLC, making it a potential therapeutic target. In the present study, A549 cells formed glycoprotein-rich lined tubular structures, and transcript levels of VM-related genes were markedly upregulated in VM-forming cells. Based on a drug repurposing strategy, it was demonstrated that doxazosin (an antihypertensive drug) displayed inhibitory activity on VM formation at non-cytotoxic concentrations. Doxazosin significantly reduced the levels of vascular endothelial growth factor A (VEGF-A) and matrix metalloproteinase-2 (MMP-2) in the cell media during VM formation. Further experiments revealed that the protein expression levels of VEGF-A and vascular endothelial-cadherin (VE-cadherin), which contribute to tumor aggressiveness and VM formation, were downregulated following doxazosin treatment. Moreover, the downstream signaling Ephrin type-A receptor 2 (EphA2)/AKT/mTOR/MMP/Laminin-5γ2 network was inhibited in response to doxazosin treatment. In conclusion, the present study demonstrated that doxazosin displayed anti-VM activity in an NSCLC cell model through the downregulation of VEGF-A and VE-cadherin levels, and the suppression of signaling pathways related to the receptor tyrosine kinase, EphA2, protein kinases, AKT and mTOR, and proteases, MMP-2 and MMP-9. These results support the add-on anti-VM effect of doxazosin as a potential agent against NSCLC.

m6A demethylase ALKBH5 maintains stemness of intrahepatic cholangiocarcinoma by sustaining BUB1B expression and cell proliferation

ALKBH5 plays critical roles in various cellular processes via post-transcriptional regulation of oncogenes or tumor suppressors in an N6-methyladenosine (m6A)-dependent manner. However, its function in intrahepatic cholangiocarcinoma (ICC) remains unclear. In the present study, bioinformatic analyses of The Cancer Genome Atlas (TCGA) data were performed, and the association of ALKBH5 in predicting overall survival in patients with ICC was investigated. Then, the clinical data of patients from The Affiliated Changzhou No. 2 People's Hospital of Nanjing Medical University (Changzhou, China) was used to reveal the overall survival of patients with ICC with different ALKBH5 expression levels by Kaplan-Meier survival analysis. Subsequently, in vitro and in vivo studies were conducted to explore and verify the downstream genes regulated by ALKBH5. The results from TCGA data demonstrated that ALKBH5 expression is elevated in ICC and that patients with high ALKBH5 expression exhibited poor survival compared with patients with low expression. In addition, in vitro assays demonstrated that ALKBH5 promoted cell viability and maintained the stemness of ICC cells, leading to ICC progression. The present study also demonstrated that BUB1 mitotic checkpoint serine/threonine kinase B (BUB1B) is the downstream gene regulated by ALKBH5 and targeting BUB1B suppressed cell growth. The in vitro and vivo experiments revealed that ALKBH5 might function through BUB1B to maintain the stemness of ICC and that altering BUB1B may suppress ICC progression.

PTTG1 induces pancreatic cancer cell proliferation and promotes aerobic glycolysis by regulating c-myc

This study aimed to clarify the role of pituitary tumor-transforming gene 1 (PTTG1) in proliferation, migration, invasion, and aerobic glycolysis of pancreatic cancer cells, and evaluate the potential of PTTG1 as a therapeutic target. PTTG1 expression in pancreatic cancers was analyzed using the GEPIA databank. In the Panc1 cell with the PTTG1 knockdown or Mia-PaCa2 cells with PTTG1 overexpression, the cell proliferation was evaluated using cell viability curves and colony formation, and wound heal assay and transwell assay were performed to evaluate the migration and invasion, respectively. Furthermore, a western blot was performed to evaluate the expressions of PTTG1, proliferating cell nuclear antigen, E-cadherin, N-cadherin, and c-myc. Meanwhile, the glucose uptake, extracellular acidification rates (ECAR), and oxygen consumption rates (OCR) were analyzed. Our results showed that PTTG1 expression is upregulated in pancreatic cancer, which promoted cell proliferation. Low PTTG1 contributed to higher disease-free survival and overall survival. In Panc1 cell, PTTG1 knockdown resulted in reduced cell viability and colony formation. The migration and invasion abilities of the cells were also reduced in Panc1 with PTTG1 knockdown. Correspondingly, PTTG1 knockdown decreased c-myc expression, glucose uptake, ECAR, and OCR in Panc1 cells. In Mia-PaCa2 cells, PTTG1 overexpression promoted cell proliferation, aerobic glycolysis, and translocation of β-catenin to the nucleus by regulating c-myc. In conclusion, PTTG1 induces proliferation, migration, and invasion, and promotes aerobic glycolysis in pancreatic cancer cells via regulating c-myc, demonstrating the potential of PTTG1 as a therapeutic target.

The role and mechanism of esketamine in preventing and treating remifentanil-induced hyperalgesia based on the NMDA receptor-CaMKII pathway

Remifentanil-induced hyperalgesia (RIH) is a common clinical phenomenon that limits the use of opioids in pain management. Esketamine, a non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist, has been shown to prevent and treat RIH. However, the underlying effect mechanism of esketamine on RIH remains unclear. This study aimed to investigate the role and mechanism of esketamine in preventing and treating RIH based on the NMDA receptor-CaMKIIα pathway. In this study, an experimental animal model was used to determine the therapeutic effect of esketamine on pain elimination. Moreover, the mRNA transcription and protein expression levels of CaMKII and GluN2B were investigated to offer evidence of the protective capability of esketamine in ameliorating RIH. The results demonstrated that esketamine attenuated RIH by inhibiting CaMKII phosphorylation and downstream signaling pathways mediated by the NMDA receptor. Furthermore, ketamine reversed the upregulation of spinal CaMKII induced by remifentanil. These findings suggest that the NMDA receptor-CaMKII pathway plays a critical role in the development of RIH, and ketamine's effect on this pathway may provide a new therapeutic approach for the prevention and treatment of RIH.

PCSK9 promotes tumor cell proliferation and migration by facilitating CCL25 secretion in esophageal squamous cell carcinoma

Proprotein convertase subtilisin/kexin type 9 (PCSK9) serves an important role in maintaining plasma cholesterol levels, and fatty acid metabolism is involved in the progression of various types of cancer. In the present study, the role of PCSK9 in the development of esophageal squamous cell carcinoma (ESCC) was investigated. PCSK9 expression was compared between ESCC and normal esophageal epithelial tissues using reverse transcription-quantitative PCR. In addition, the association between PCSK9 expression and clinical staging and prognosis was assessed by immunohistochemistry. The effects of PCSK9 overexpression or knockdown on cell proliferation was evaluated using Cell Counting Kit-8 and colony formation assays. The invasion and migration of cancer cells was assessed using wound healing and Transwell assays. Western blotting was performed to evaluate changes in the expression levels of epithelial-mesenchymal transition (EMT)-related proteins. ELISA was performed to detect the effects of PCSK9 on chemokine (C-C motif) ligand 25 (CCL25) secretion. The results revealed that PCSK9 was highly expressed in ESCC tissues compared with that in normal esophageal tissues, and the high expression of PCSK9 was associated with a poor prognosis. Furthermore, PCSK9 could promote the proliferation, migration and invasion of ESCC cells in vitro. Mechanistically, PCSK9 could promote EMT by secreting CCL25. In conclusion, patients with ESCC may benefit from a novel therapeutic strategy based on these findings.

Single domain antibodies specific for HER2 dimerization domain effectively disrupts HER2 dimerization

Dimer-dependent phosphorylation of HER2 receptor is a key event for the signal transduction of HER family of receptors which correlates with tumor invasion and metastasis. New generation of therapies based on dimerization domain inhibition using monoclonal or fragment antibodies was introduced. A potent method for manufacturing antibodies and antibody fragments is the phage display antibody library method. A recombinant phage was generated using the phage display method from synthetic dAb library. Subtractive biopanning was performed on sepharose 4b resin. Evaluation of success of subtractive biopanning was confirmed by the PCR fingerprinting after the fourth round of biopanning. The fourth round of biopanning results in the isolation of several dimerization domain reactive clones based on the polyclonal phage ELISA results. Monoclonal phage cell ELISA was used to select the positive clones with the highest affinity, and they were subsequently employed for functional tests. Cell-ELISA, MTT assay and dimerization inhibition test revealed that the reactivity and specificity of the selected monoclonal phage to dimerization domain of HER2. Further, Annexin V/PI staining and gene expression analysis showed that increased apoptosis rates. Also, in silico binding of the selected clones to conformational structure of HER2 was applied, using protein-protein docking tool of the ICM-Pro software, and showed sdAbs were specifically interacted with dimerization domain of the receptor. In conclusion, we have identified a single domain targeting HER2 dimerization, which represents a promising therapeutic and diagnostic candidate for HER2-positive cancers. Purified sdAb needs to more research to evaluate it both in vivo and in vitro via functional tests to determine if it can be applied for treatment and diagnostics.

Fine particulate matter promotes airway inflammation and mucin production by activating endoplasmic reticulum stress and the IRE1α/NOD1/NF‑κB pathway

Fine particulate matter (PM2.5) is a type of small particle that is <2.5 µm in diameter that may cause airway inflammation. Thus, the present study aimed to explore the effects of PM2.5 on endoplasmic reticulum (ER) stress and airway inflammation in human airway epithelial cells. For this purpose, HBE135‑E6E7 airway epithelial cells were cultured and exposed to specific concentrations of PM2.5 for various periods of time, and cell viability was determined using a Cell Counting Kit‑8 assay. The results of the present study demonstrated that exposure to PM2.5 increased the mRNA and protein expression levels of interleukin (IL)‑6, tumor necrosis factor (TNF)‑α and mucin 5AC (MUC5AC). Moreover, the expression levels of ER stress‑related proteins, such as glucose‑regulated protein 78, CCAAT‑enhancer binding protein homologous protein, activating transcription factor 6, protein kinase R‑like ER kinase (PERK), phosphorylated (p‑)PERK, inositol‑requiring enzyme 1α (IRE1α) and p‑IRE1α, and nucleotide‑binding oligomerization domain 1 (NOD1) expression levels were increased following exposure to PM2.5. Transfection with IRE1α small interfering RNA (siRNA) led to the increased production of IL‑6, TNF‑α and MUC5AC. Moreover, the expression of NOD1 and the translocation of NF‑κB p65 were inhibited following transfection with IRE1α siRNA. In addition, the results of the present study demonstrated that transfection with NOD1 siRNA decreased the production of IL‑6, TNF‑α and MUC5AC, and decreased the translocation of NF‑κB p65. The expression levels of IL‑6, TNF‑α and MUC5AC were increased in the HBE135‑E6E7 cells following treatment with C12‑iE‑DAP, a NOD1 agonist. Moreover, treatment with C12‑iE‑DAP led to the activation of NF‑κB p65. Collectively, the results of the present study suggest that PM2.5 promotes airway inflammation and mucin production by activating ER stress in HBE135‑E6E7 airway epithelial cells, and that the IRE1α/NOD1/NF‑κB pathway may be involved in this process.