TMEM119 promotes gastric cancer cell migration and invasion through STAT3 signaling pathway

The role of TMEM119 in gastric adenocarcinoma and its specific effects on immunity

ObjectiveTo investigate the prognostic significance and immunological implication of transmembrane protein 119 (TMEM119) in stomach adenocarcinoma (STAD).MethodsThis study included STAD-associated data obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. In addition, TMEM119 expression levels were analysed by immunohistochemistry in tissue samples from patients with STAD (with microsatellite instability or microsatellite stability). Gene Set Enrichment Analysis (GSEA) was conducted to explore signalling pathways related to TMEM119 in STAD. Additionally, CIBERSORT and ESTIMATE algorithms were applied to examine the relationship between TMEM119 expression and tumour-infiltrating immune cells, as well as the tumour microenvironment.ResultsSurgical specimens from 100 patients with STAD (50 each with microsatellite stability or microsatellite instability); TCGA RNA-sequence and clinical data from 375 STAD tumour tissues and 32 paracancerous tissues; and two GEO datasets (GSE27342, comprising 80 paracancerous tissues and 80 tumour tissues; and GSE84437, comprising 433 tumour samples) were analysed. TMEM119 was found to be elevated in STAD, and associated with poor prognosis. Clinical gastric cancer tissues exhibited increased TMEM119 expression. TMEM119 was enriched in immune-related functions and pathways. TMEM119 correlated with immune checkpoint genes, tumour mutational burden, and microsatellite instability. TMEM119 was positively correlated with tumour-infiltrating immune cells, tumour microenvironment, mannose receptor C-type I (CD206), and programmed cell death-ligand 1 (PD-L1), while inversely related to nitric oxide synthase 2.ConclusionsTMEM119 may be a potential immune-related biomarker for STAD prognosis and therapeutic targeting.

The emerging role of transmembrane proteins in tumorigenesis and therapy

Transmembrane proteins (TMEMs) are a kind of proteins that can cross the phospholipid bilayer one or multiple times and remain permanently anchored. They are involved in the regulation of many biological functions, and their dysregulation is associated with many human diseases and even cancer. Abnormal expression alterations of TMEMs widely exist in tumor tissues compared with paracancerous tissues. They are associated with the clinicopathological features of cancer patients by promoting or inhibiting the development of cancer, thus affecting survival. This review summarized the structure and physiological functions of TMEMs, as well as their roles in tumorigenesis, such as cell proliferation, apoptosis, autophagy, adhesion, metastasis, metabolism and drug resistance. In addition, we elaborated on the potentiality of TMEMs for tumor immunity. Moreover, the advances of TMEMs were subsequently retrospected in several common types of human cancers, including breast cancer, gastric cancer, and lung cancer. Subsequently, we outlined the targeted therapeutic strategies against TMEMs proposed based on existing studies. To date, there are still many TMEMs whose functions and mechanisms have not been well known due to their special structures. Since the important roles TMEMs plays in the development of human cancers, it is urgent to portray their structure and function in carcinogenesis, providing potential biomarkers for cancer patients in the future.

GGT5 as a promising prognostic biomarker and its effects on tumor cell progression in gastric cancer

Background

Gastric cancer (GC) is a gastric malignant tumor with over 1 million new cases globally each year. There are many diagnostic methods for GC, but due to the hidden early symptoms of GC, early GC is easy to be missed and misdiagnosed, which affects the follow-up treatment of patients. The early and accurate diagnosis of GC is of great significance for the treatment and survival of GC patients. Our laboratory study found that gamma-glutamyl transferase (GGT) was highly expressed in GC patients, but the mechanism of GGT family genes in the occurrence and development of GC remained to be further studied. Therefore, this study aimed to explore the mechanism of GGT family functional gene GGT5 regulating the proliferation and migration of GC cells, and provide a possible new biomarker for the early diagnosis of GC.

Methods

The value of serum GGT in GC patients was first statistically analyzed. Then, The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) datasets were used to analyze the mRNA expression of GGT5 in GC, and its clinical relationship and function. Furthermore, expression of GGT5 was reduced by lentivirus RNA interference and verified by polymerase chain reaction (PCR), Cell Counting Kit-8 (CCK-8) and 5-ethynyl-2'-deoxyuridine (EdU) assays were used to detect cell proliferation after GGT5 knockdown. Scratch and Transwell assays were applied to observe cell migration after knockdown of GGT5. Finally, Western blot assays were observed to demonstrate PI3K/AKT-MAPK and MMPs expression levels after knockdown of GGT5.

Results

Serum GGT was expressed at a high level in GC patients. GGT5 was highly expressed in GC tissues, and was associated with poor prognosis and clinical stage of GC. GGT5 might be involved in the regulation of vascular development and angiogenesis, as well as in the mechanisms of cell motility and migration, and it was positively correlated with the PI3K/AKT pathway. The proliferation and migration capacity of GC cells was dampened by downregulation of GGT5. GGT5 mediated proliferation and migration of GC cells by directly targeting PI3K/AKT-MAPK-MMPs pathways.

Conclusions

Low expression of GGT5 reduced proliferation and migration in GC cells by modulating the PI3K/AKT-MAPK-MMPs pathway, and GGT5 might be a new target for GC.

Personalized identification and characterization of genome-wide gene expression differences between patient-matched intracranial and extracranial melanoma metastasis pairs

Melanoma is the most serious type of skin cancer that frequently spreads to other organs of the human body. Especially melanoma metastases to the brain (intracranial metastases) are hard to treat and a major cause of death of melanoma patients. Little is known about molecular alterations and altered mechanisms that distinguish intra- from extracranial melanoma metastases. So far, almost all existing studies compared intracranial metastases from one set of patients to extracranial metastases of an another set of melanoma patients. This neglects the important facts that each melanoma is highly individual and that intra- and extracranial melanoma metastases from the same patient are more similar to each other than to melanoma metastases from other patients in the same organ. To overcome this, we compared the gene expression profiles of 16 intracranial metastases to their corresponding 21 patient-matched extracranial metastases in a personalized way using a three-state Hidden Markov Model (HMM) to identify altered genes for each individual metastasis pair. This enabled three major findings by considering the predicted gene expression alterations across all patients: (i) most frequently altered pathways include cytokine-receptor interaction, calcium signaling, ECM-receptor interaction, cAMP signaling, Jak-STAT and PI3K/Akt signaling, (ii) immune-relevant signaling pathway genes were downregulated in intracranial metastases, and (iii) intracranial metastases were associated with a brain-like phenotype gene expression program. Further, the integration of all differentially expressed genes across the patient-matched melanoma metastasis pairs led to a set of 103 genes that were consistently down- or up-regulated in at least 11 of the 16 of the patients. This set of genes contained many genes involved in the regulation of immune responses, cell growth, cellular signaling and transport processes. An analysis of these genes in the TCGA melanoma cohort showed that the expression behavior of 11 genes was significantly associated with survival. Moreover, a comparison of the 103 genes to three closely related melanoma metastasis studies revealed a core set of eight genes that were consistently down- or upregulated in intra- compared to extracranial metastases in at least two of the three related studies (down: CILP, DPT, FGF7, LAMP3, MEOX2, TMEM119; up: GLDN, PMP2) including FGF7 that was also significantly associated with survival. Our findings contribute to a better characterization of genes and pathways that distinguish intra- from extracranial melanoma metastasis and provide important hints for future experimental studies to identify potential targets for new therapeutic approaches.

Tmem119 is involved in bone anabolic effects of PTH through enhanced osteoblastic bone formation in mice

The intermittent administration of parathyroid hormone (PTH) exerts potent bone anabolic effects, which increase bone mineral density (BMD) and reduce fracture risk in osteoporotic patients. However, the underlying mechanisms remain unclear. Tmem119 has been proposed as a factor that is closely linked to the osteoblast phenotype, and we previously reported that PTH enhanced the expression of Tmem119 in mouse osteoblastic cells. However, roles of Tmem119 in the bone anabolic effects of PTH in vivo remain unknown. We herein investigated the roles of Tmem119 in bone anabolic effects of PTH using Tmem119-deficient mice. Tmem119 deficiency significantly reduced PTH-induced increases in trabecular bone volume and cortical BMD of femurs. Effects of Tmem119 deficiency on bone mass seemed predominant in female mice. Histomorphometric analyses with calcein labeling showed that Tmem119 deficiency significantly attenuated PTH-induced increases in the rates of bone formation and mineralization as well as numbers of osteoblasts. Moreover, Tmem119 deficiency significantly blunted PTH-induced decreases in phosphorylation of β-catenin and increases in alkaline phosphatase activity in osteoblasts. In conclusion, the present results indicate that Tmem119 is involved in bone anabolic effects of PTH through osteoblastic bone formation partly related to canonical Wnt-β-catenin signaling in mice.

TMEM119 (c.G143A, p.S48L) Mutation Is Involved in Primary Failure of Eruption by Attenuating Glycolysis-Mediated Osteogenesis

Primary failure of eruption (PFE) is a rare oral disease with an incidence rate of 0.06%. It is characterized by abnormal eruption mechanisms that disrupt tooth eruption. The underlying pathogenic genetic variant and mechanism of PFE remain largely unknown. The purpose of this study was to explore the role of a novel transmembrane protein 119 (TMEM119) mutation in two PFE patients in a Chinese family. Information collection was performed on the family with a diagnosis of PFE, and blood samples from patients and healthy family members were extracted. Whole-exome sequencing was performed. Bioinformatics analysis revealed that a heterozygous variant in the TMEM119 gene (c.G143A, p.S48L) was a disease-associated mutation in this family. Recombinant pcDNA3.1 plasmid-containing wild-type and mutant TMEM119 expression cassettes were successfully constructed and transfected into MC3T3-E1 cells, respectively. The results of in vitro analysis suggested that the subcellular distribution of the TMEM119 protein was transferred from the cell cytoplasm to the nucleus, and the ability of cells to proliferate and migrate as well as glycolytic and mineralized capacities were reduced after mutation. Furthermore, rescue assays showed that activating transcription factor 4 (ATF4) overexpression rescued the attenuated glycolysis and mineralization ability of cells. Results of in vivo analysis demonstrated that TMEM119 was mainly expressed in the alveolar bone around the mouse molar germs, and the expression level increased with tooth eruption, demonstrated using immunohistochemistry and immunofluorescence. Collectively, the novel TMEM119 mutation is potentially pathogenic in the PFE family by affecting the glucose metabolism and mineralized function of osteoblasts, including interaction with ATF4. Our findings broaden the gene mutation spectrum of PFE and further elucidate the pathogenic mechanism of PFE.

The transmembrane proteins (TMEM) and their role in cell proliferation, migration, invasion, and epithelial-mesenchymal transition in cancer

Transmembrane proteins (TMEM) are located in the different biological membranes of the cell and have at least one passage through these cellular compartments. TMEM proteins carry out a wide variety of functions necessary to maintain cell homeostasis TMEM165 participates in glycosylation protein, TMEM88 in the development of cardiomyocytes, TMEM45A in epidermal keratinization, and TMEM74 regulating autophagy. However, for many TMEM proteins, their physiological function remains unknown. The role of these proteins is being recently investigated in cancer since transcriptomic and proteomic studies have revealed that exits differential expression of TMEM proteins in different neoplasms concerning cancer-free tissues. Among the cellular processes in which TMEM proteins have been involved in cancer are the promotion or suppression of cell proliferation, epithelial-mesenchymal transition, invasion, migration, intravasation/extravasation, metastasis, modulation of the immune response, and response to antineoplastic drugs. Inclusive data suggests that the participation of TMEM proteins in these cellular events could be carried out through involvement in different cell signaling pathways. However, the exact mechanisms not clear. This review shows a description of the involvement of TMEM proteins that promote or decrease cell proliferation, migration, and invasion in cancer cells, describes those TMEM proteins for which both a tumor suppressor and a tumor promoter role have been identified, depending on the type of cancer in which the protein is expressed. As well as some TMEM proteins involved in chemoresistance. A better characterization of these proteins is required to improve the understanding of the tumors in which their expression and function are altered; in addition to improving the understanding of the role of these proteins in cancer will show those TMEM proteins be potential candidates as biomarkers of response to chemotherapy or prognostic biomarkers or as potential therapeutic targets in cancer.

Landscape of Druggable Molecular Pathways Downstream of Genomic CDH1/Cadherin-1 Alterations in Gastric Cancer

Loss of CDH1/Cadherin-1 is a common step towards the acquisition of an abnormal epithelial phenotype. In gastric cancer (GC), mutation and/or downregulation of CDH1/Cadherin-1 is recurrent in sporadic and hereditary diffuse GC type. To approach the molecular events downstream of CDH1/Cadherin-1 alterations and their relevance in gastric carcinogenesis, we queried public databases for genetic and DNA methylation data in search of molecular signatures with a still-uncertain role in the pathological mechanism of GC. In all GC subtypes, modulated genes correlating with CDH1/Cadherin-1 aberrations are associated with stem cell and epithelial-to-mesenchymal transition pathways. A higher level of genes upregulated in CDH1-mutated GC cases is associated with reduced overall survival. In the diffuse GC (DGC) subtype, genes downregulated in CDH1-mutated compared to cases with wild type CDH1/Cadherin-1 resulted in being strongly intertwined with the DREAM complex. The inverse correlation between hypermethylated CpGs and CDH1/Cadherin-1 transcription in diverse subtypes implies a common epigenetic program. We identified nonredundant protein-encoding isoforms of 22 genes among those differentially expressed in GC compared to normal stomach. These unique proteins represent potential agents involved in cell transformation and candidate therapeutic targets. Meanwhile, drug-induced and CDH1/Cadherin-1 mutation-related gene expression comparison predicts FIT, GR-127935 hydrochloride, amiodarone hydrochloride in GC and BRD-K55722623, BRD-K13169950, and AY 9944 in DGC as the most effective treatments, providing cues for the design of combined pharmacological treatments. By integrating genetic and epigenetic aspects with their expected functional outcome, we unveiled promising targets for combinatorial pharmacological treatments of GC.

SNAT2/SLC38A2 Confers the Stemness of Gastric Cancer Cells via Regulating Glutamine Level

BACKGROUND

Glutamine (Gln) is essential for cancer progression, however, few studies have been conducted to investigate the roles of Gln transporters in gastric cancer stem cells (CSCs).

AIMS

This work aims to explore the roles of Gln transporters in gastric cancer cell stemness.

METHODS

We collected spheres formed by gastric cancer (GC) cells through a 3-dimensional (3D) semisolid culture system which has been shown to hold CSC-like traits. Lentivirus package was used to construct GC cells with SNAT2 overexpression. Analysis of sphere-formation, stemness marker expression, ALDH activity were used to detect the effects of Gln transporters on GC cell stemness. Determination of reactive oxygen species (ROS) and Gln consumption combined with the methods analyzing cell stemness were performed to explore the underlying mechanisms.

RESULTS

Gln consumption was upregulated in GC spheres compared to the parental GC cells. The Gln transporter SNAT2 was highly expressed in GC spheres compared to that in the parental GC cells. SNAT2 overexpression significantly increased the Gln consumption in GC cells and increased the expression of stemness markers, sphere-formation ability and ALDH activity. Notably, SNAT2-mediated promoting effects on GC cell stemness were rescued by Gln deprivation. What's more, high expression of SNAT2 was associated with a poor GC patient survival through different online datasets.

CONCLUSIONS

SNAT2 can promote the stemness of GC cells in a Gln-dependent manner.

Transmembrane protein TMEM119 facilitates the stemness of breast cancer cells by activating Wnt/β-catenin pathway

The effects of transmembrane protein 119 (TMEM119) on breast cancer progression have not been elucidated. This study aims to investigate the roles of TMEM119 in breast cancer progression. Clinical samples and online datasets were used to determine TMEM119 expression and its correlation between patients’ survival. Wound healing, transwell invasion, mammary spheroid formation, and ALDH activity were performed to detect the effects of TMEM119. RNA-sequencing, Luciferase report analysis, Co-IP, and ChIP analysis were constructed to reveal the underlying mechanisms. We found that TMEM119 was highly expressed in breast cancer tissues and cells compared to that in normal tissues and cells. Additionally, TMEM119 expression was negatively correlated with the survival of breast cancer patients. TMEM119 knockdown reduced the expression of stemness markers, mammary spheroid-formation ability and ALDH activity. RNA-sequencing analysis indicated that Wnt/β-catenin signaling was enriched in cells with TMEM119 overexpression. Further co-IP experiments indicated that TMEM119 interacted with β-catenin and maintained its protein stability. Conversely, β-catenin directly bound to TMEM119 gene promoter and thus increased TMEM119 transcriptional activity and its expression. Finally, we demonstrated that TMEM119-mediated effects depended on Wnt/β-catenin signaling. Thus, this work reveals a novel TMEM119-β-catenin positive feedback loop essential for breast cancer cell stemness.

TMEM119 facilitates ovarian cancer cell proliferation, invasion, and migration via the PDGFRB/PI3K/AKT signaling pathway

Background

Ovarian cancer (OV) is the deadliest gynecological cancer. Transmembrane protein 119 (TMEM119) has been reported as oncogene in several human cancers. However, the function of TMEM119 in OV is still poorly known.

Methods

Western blot and qRT-PCR were used to analyze TMEM119 levels. Transwell assays, wound healing assays, CCK-8 assays and EdU cell proliferation assays were designed to explore the function and potential mechanism of TMEM119 in malignant biological behaviors in OV.

Results

TMEM119 was observed to be overexpressed in OV tissues and associated with poor survival in OV patients. Knockdown and overexpression experiments demonstrated that TMEM119 promoted proliferation, invasion, and migration in OV cells in vitro. TMEM119 mRNA expression was related to the pathways of focal adhesion according to Gene Set Enrichment Analyses and was correlated with the mRNA expression level of platelet-derived growth factor receptor beta (PDGFRB). TMEM119 exerted oncogenic effects partially by regulating the expression of PDGFRB and by activating the PI3K/AKT signaling pathway.

Conclusions

Collectively, our findings highlight the potential role of TMEM119 in the malignant biological behavior of OV, which may serve as a potential biomarker and a therapeutic candidate for OV.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-02781-x.

RTKN2 is Associated with Unfavorable Prognosis and Promotes Progression in Non-Small-Cell Lung Cancer

Background

Non-small-cell lung cancer (NSCLC) is the leading cause of cancer-related mortality worldwide. However, the molecular mechanism of NSCLC remains unknown. Accumulating data show that Rhotekin 2 (RTKN2) functions as a novel crucial regulator of diverse biological processes; however, its pathological role in NSCLC remains unclear.

Methods

In this study, we investigated the function of RTKN2 in NSCLC. The expression of RTKN2 mRNA was analyzed in tumor tissues and paired adjacent tissues from patients by qRT-PCR. The role of RTKN2 in cell proliferation, apoptosis, migration, and invasion was investigated. The potential mechanisms were explored.

Results

We found that the level of RTKN2 mRNA was up-regulated in NSCLC tissues and cell lines. RTKN2 knockout inhibited the proliferation of human NSCLC cell lines A549 via inducing apoptosis by increasing the level of Bax and decreasing the level of Bcl-2. Furthermore, silencing of RTKN2 reduced the migration and invasion of A549 cells through up-regulated matrix metalloproteinase-9 (MMP9) and MMP2 expression.

Conclusion

These data suggest that RTKN2 may not only be a prognostic biomarker candidate but also provide a potential therapeutic target for NSCLC diagnosis and treatment.

Capn4 contributes to tumor invasion and metastasis in gastric cancer via activation of the Wnt/β-catenin/MMP9 signalling pathways

Capn4, a small regulatory subunit of the calpain proteolytic system, functions as a potential tumor promoter in several cancers. However, the biological functions and molecular mechanisms of Capn4 in gastric cancer (GC) remain poorly understood. In the current study, we found that upregulation of Capn4 was detected frequently in GC tissues, and was associated with significantly worse survival among the GC patients. Multivariate analyses revealed that abundance of Capn4 was an independent predictive marker for the poor prognosis of GC. Further, Capn4 knockdown notably suppressed GC invasion and metastasis in vitro. Consistently, a xenograft assay showed that silencing of Capn4 in GC cells suppressed their dissemination to lung tissue in vivo. Moreover, our results indicated that Capn4 promotes gastric cancer metastasis by increasing MMP9 expression, and demonstrated that MMP9 is crucial for the pro-metastasis role of Capn4 in GC cells. Further investigation revealed that Capn4 regulated MMP9 expression via activation of Wnt/β-catenin signaling pathway. Mechanistically, we found that Capn4 can decreased β-catenin ubiquitination to enhance the protein stability of β-catenin in GC cells. Collectively, Capn4 has a central role in gastric cancer metastasis, which could be a potential diagnostic and therapeutic target for GC.

STAT3 Pathway in Gastric Cancer: Signaling, Therapeutic Targeting and Future Prospects

Molecular signaling pathways play a significant role in the regulation of biological mechanisms, and their abnormal expression can provide the conditions for cancer development. The signal transducer and activator of transcription 3 (STAT3) is a key member of the STAT proteins and its oncogene role in cancer has been shown. STAT3 is able to promote the proliferation and invasion of cancer cells and induces chemoresistance. Different downstream targets of STAT3 have been identified in cancer and it has also been shown that microRNA (miR), long non-coding RNA (lncRNA) and other molecular pathways are able to function as upstream mediators of STAT3 in cancer. In the present review, we focus on the role and regulation of STAT3 in gastric cancer (GC). miRs and lncRNAs are considered as potential upstream mediators of STAT3 and they are able to affect STAT3 expression in exerting their oncogene or onco-suppressor role in GC cells. Anti-tumor compounds suppress the STAT3 signaling pathway to restrict the proliferation and malignant behavior of GC cells. Other molecular pathways, such as sirtuin, stathmin and so on, can act as upstream mediators of STAT3 in GC. Notably, the components of the tumor microenvironment that are capable of targeting STAT3 in GC, such as fibroblasts and macrophages, are discussed in this review. Finally, we demonstrate that STAT3 can target oncogene factors to enhance the proliferation and metastasis of GC cells.

rs2072580T>A Polymorphism in the Overlapping Promoter Regions of the SART3 and ISCU Genes Associated with the Risk of Breast Cancer

We analyzed association of potentially regulatory polymorphisms (rs590352, rs11542583, rs3829202, rs207258, and rs4796672) with breast cancer. A significant association was found between this disease and rs2072580T>A (p=0.001) located in the overlapping promoter regions of the SART3 and ISCU genes. In women with AA and AT genotypes, the risk of breast cancer is higher by 6.7 times (p=0.001) and 12 times (p=0.001), respectively, in comparison with TT genotype. Under a codominant model of inheritance (AT vs AA+TT), the risk of breast cancer was increased by 4.2 times (р=0.001) for the AT genotype. Under a recessive model of inheritance (TT vs AA+TT), the risk of disease was 10-fold higher (р=0.001) for the TT genotype. It has been demonstrated that the T>A substitution affects the binding properties of transcription factors CREB1 and REST.

Articular Cartilage Stem Cells Influence the Postoperative Repair of Hip Replacement by Regulating Endoplasmic Reticulum Stress in Chondrocytes via PERK Pathway

OBJECTIVE

Endoplasmic reticulum stress (ERS) is present in chondrocytes of osteoarthritis, and the intensity of ERS is related to the degree of cartilage degeneration. In vitro intervention strategies can change the status of ERS and induce the inhibition of ERS-related pathway. Therefore, this study is designed to explore the role and molecular mechanism of cartilage stem cells (ACSCs) of ERS in chondrocytes after hip replacement.

METHODS

Human cartilage cell lines C28/I2 were cultured as the control group. The ERS inducer was added into C28/I2 as ERS group. The third ERS + stem cells group was formed by adding cartilage stem cells into ERS group, and further transfection of si-PERK was defined as si-PERK + ERS + stem cells group. Cell cycle and apoptosis in the four groups were determined by flow cytometry. The protein expression of GRP78, PERK, ATF4, TMEM119, CDK4, Cyclin D, and BMP6 in chondrocytes in the four groups were investigated by western blot, and the distribution of PERK, TMEM119, and BMP6 in chondrocytes were observed by immunofluorescence assay. In addition, the transcriptional levels of Bcl2, Bax, and Caspase 3 were also determined by RT-PCR.

RESULTS

In cell cycle assay, ERS increased the accumulation of cells in G0 /G1 and G2 /M, while cartilage stem cells weakened the effects. The apoptosis rates in control group, ERS, ERS + stem cells, si-PERK + ERS + stem cells were 0%, 21.3%, 18.9%, and 15.9%, respectively, and the difference of apoptosis rate between the latter three groups and control group was statistically significant (P < 0.01). Stem cells could weaken the ERS-induced cell apoptosis, especially reducing the number of cells in the late stage of apoptosis from 5.4% to 1.1%. The protein level of GRP78, PERK, ATF4, TMEM119, and BMP6 in the group of ERS, ERS + stem cells, and si-PERK + ERS + stem cells were all significantly higher than those in control group, and the group of ERS + stem cells was the highest, all of the differences were significant (P < 0.01). However, the protein level of CDK4 and Cyclin D presented an absolutely opposite trend and the difference was still significant (P < 0.05). The group of si-PERK + ERS + stem cell was lower than those in the group of ERS + stem cell but higher than those in the group of ERS (P < 0.05). The level of Caspase 3 in the latter three groups was significantly higher than those in the control group, and the group of ERS was the highest (P < 0.01). Besides, the relative level of Bcl-2/Bax in control group was 1, but the group of ERS was about 0.5, and there was significant difference (P < 0.01). The ratio of Bcl-2/Bax in the group of ERS + stem cells was more than 2 and significantly higher than those of other groups.

CONCLUSION

ACSCs could reduce ERS-induced chondrocyte apoptosis by PERK and Bax/Bcl-2 signaling pathway.