De-ubiquitination of SAMHD1 by USP7 promotes DNA damage repair to overcome oncogenic stress and affect chemotherapy sensitivity.

Oncogenic stress induces DNA damage repair (DDR) that permits escape from mitotic catastrophe and allows early precursor lesions during the evolution of cancer. SAMHD1, a dNTPase protecting cells from viral infections, has been recently found to participate in DNA damage repair process. However, its role in tumorigenesis remains largely unknown. Here, we show that SAMHD1 is up-regulated in early-stage human carcinoma tissues and cell lines under oxidative stress or genotoxic insults. We further demonstrate that de-ubiquitinating enzyme USP7 interacts with SAMHD1 and de-ubiquitinates it at lysine 421, thus stabilizing SAMHD1 protein expression for further interaction with CtIP for DDR, which promotes tumor cell survival under genotoxic stress. Furthermore, SAMHD1 levels positively correlates with USP7 in various human carcinomas, and is associated with an unfavorable survival outcome in patients who underwent chemotherapy. Moreover, USP7 inhibitor sensitizes tumor cells to chemotherapeutic agents by decreasing SAMHD1 in vitro and in vivo. These findings suggest that de-ubiquitination of SAMHD1 by USP7 promotes DDR to overcome oncogenic stress and affect chemotherapy sensitivity.

Oxidative stress impairs the Nur77-Sirt1 axis resulting in a decline in organism homeostasis during aging.

Sirt1 is an NAD+ -dependent deacetylase that protects against premature aging and cell senescence. Aging accompanied by oxidative stress leads to a decrease in Sirt1 levels and activity, but the regulatory mechanism that connects these events remains unclear. Here, we reported that Nur77, which shares similar biological pathways with Sirt1, was also decreased with age in multiple organs. Our in vivo and in vitro results revealed that Nur77 and Sirt1 decreased during aging and oxidative stress-induced cell senescence. Deletion of Nr4a1 shortened the lifespan and accelerated the aging process in multiple mouse tissues. Overexpression of Nr4a1 protected the Sirt1 protein from proteasomal degradation through negative transcriptional regulation of the E3 ligase MDM2. Our results showed that Nur77 deficiency markedly aggravated aging-related nephropathy and elucidated a key role for Nur77 in the stabilization of Sirt1 homeostasis during renal aging. We proposed a model wherein a reduction of Nur77 in response to oxidative stress promotes Sirt1 protein degradation through MDM2, which triggers cell senescence. This creates additional oxidative stress and provides positive feedback for premature aging by further decreasing Nur77 expression. Our findings reveal the mechanism by which oxidative stress reduces Sirt1 expression during aging and offers an attractive therapeutic strategy for targeting aging and homeostasis in organisms.

Application of different microcarrier cell culture technologies in biological product field / 中国生物制品学杂志

@#The productivity of cells per unit area determines the scale-up potential of the cell culture process,and the largescale application of the microcarrier system provides space for the high-yield culture of anchorage-dependent animal cells. The microcarrier animal cell culture technology is suitable for efficient production process development and optimized amplification. In recent years,microcarrier-based culture technology has been widely used in various types of animal cell culture to produce many important biological products such as vaccines,enzymes,hormones,antibodies,interferons and other probiotics. In this paper,the research progress of domestic and foreign microcarrier cell culture technology,the comparison of new microcarriers and traditional microcarriers and their applications were reviewed,so as to provide reference for the in-depth research and application of large-scale cell culture technology based on new microcarriers.

Preparation of graphene oxide/polydopamine-curcumin composite nanomaterials and its antibacterial effect against Staphylococcus aureus induced by white light.

Curcumin (Cur) plays a key role in photodynamic antibacterial activity as a photosensitizer. On the other hand, the antimicrobial potential of graphene oxide (GO) has been reported controversially, and how to improve its antimicrobial ability has become an meaningful study. In this study, we prepared polydopamine-curcumin (PDA-Cur) by pi-pi stacking and loaded it onto the GO surface to obtain GO/PDA-Cur composite nanomaterials. GO/PDA-Cur was characterized by physical and optical means, and GO/PDA-Cur possessed good dispersion and stability in water. In vitro antibacterial results showed that GO/PDA-Cur mediated photodynamic therapy significantly reduced Gram-positive Staphylococcus aureus (S. aureus) by 4 orders of magnitude with a bactericidal rate of 99.99 %. The antibacterial mechanism stems from the fact that GO/PDA-Cur can generate reactive oxygen species (ROS) under white light irradiation (405-780 nm), which causes bacterial outer membrane breakage and cellular deformation. In addition, GO/PDA-Cur has good biocompatibility. The antibacterial ability of graphene oxide was significantly improved by combining it with PDA-Cur, which allows it to be used as a photodynamic antibacterial material.

Acute percheron infarction: a precision learning.

BACKGROUND: So far, the diagnosis of acute artery of percheron (AOP) infarction is uncommon. In this study, patients with acute AOP infarction were studied to explore the relationship of imaging findings, clinical manifestations and prognosis of acute AOP infarction. MATERIALS: A total of 23 patients with acute AOP infarction in our institution from 2014 to 2019 were reviewed retrospectively. All cases were evaluated by computed tomography (CT) and magnetic resonance imaging (MRI). The modified Rankin scale (MRS), blood examination, electrocardiogram and transthoracic echocardiography were used for detailed clinical and prognostic evaluation. All standard risk factors for these patients were recorded. The MRS scores were performed 90 days after discharge. RESULTS: Four different types of acute AOP infarction were identified: (a) bilateral paramedian thalamic infarction (BPTI, 52%); (b) bilateral paramedian thalamic with rostral midbrain infarction (BPTRMI, 30%), (c) bilateral paramedian and anterior thalamic infarction (BPATI, 13%), and (d) bilateral paramedian thalamic with red nuclei infarction (BPTRNI, 4%). These patients had consciousness disorder, memory dysfunctions, vertical gaze paresis and mesencephalothalamic syndrome. The 65% of patients with BPTI and BPATI experienced relatively good functional recovery and could carry out daily life activities (MRS score ≤ 2). However, patients with BPTRMI may have an unfavorable outcome. CONCLUSIONS: Although the clinical features are variable, DWI or ADC map can improve the diagnosis of acute AOP infarction patterns. Acute AOP occlusion requires immediate diagnosis and treatment to obtain more favorable outcome and avoid additional unnecessary procedures.

Nur77 ameliorates age-related renal tubulointerstitial fibrosis by suppressing the TGF-ß/Smads signaling pathway.

Nerve growth factor-induced gene B (Nur77) has been shown to ameliorate several biological processes in chronic diseases, including inflammatory response, cellular proliferation, and metabolism. Chronic kidney disease (CKD) is characterized by tubulointerstitial fibrosis for which no targeted therapies are available as yet. In this study, we performed in vivo and in vitro experiments to demonstrate that Nur77 targets fibrosis signals and attenuates renal tubulointerstitial fibrosis during the aging process. We observed that the TGF-ß/Smads signal pathway was significantly suppressed by Nur77, suggesting that Nur77 controlled the activation of key steps in TGF-ß/Smads signaling. We further showed that Nur77 interacted with Smad7, the main repressor of nuclear translocation of Smad2/3, and stabilized Smad7 protein homeostasis. Nur77 deficiency resulted in Smad7 degradation, aggravating Smad2/3 phosphorylation, and promoting transcription of its downstream target genes, ACTA2 and collagen I. Our findings demonstrate that Nur77 is a potential therapeutic target for age-related kidney diseases including CKD. Maintenance of Nur77 may be an effective strategy for blocking renal tubulointerstitial fibrosis and improving renal function in the elderly.

The HSP90 inhibitor, XL888, enhanced cell apoptosis via downregulating STAT3 after insufficient radiofrequency ablation in hepatocellular carcinoma.

AIMS: Radiofrequency ablation (RFA) is the first-line option for early-stage hepatocellular carcinoma (HCC). However, the residual tumor attributed to insufficient RFA (iRFA) led to tumor recurrence and metastasis. Novel combination strategies are urgently needed to enhance efficiency of RFA. MAIN METHODS: For in vitro iRFA models, HCC cells were placed in a water bath at 46 °C for 10 min and then returned to the original incubator. For in vivo models, HCC cells were implanted subcutaneously into nude mice. The nude mice were then randomly assigned into 4 groups: control group, XL888 group, iRFA group, combination of XL888 and iRFA group. CCK8 was performed to detect cell viability; Hoechst 33258 was used to explore nuclear morphology; The expression levels of proteins were demonstrated by western blotting; Co-localization of HSP90 and STAT3 was elucidated by immunofluorescence confocal microscopy; Immunohistochemistry was used to explore expression levels of proteins at tissue level. KEY FINDINGS: XL888 promoted apoptosis of HCC cells induced by heat via inhibiting expression levels of Mcl-1 and cleaved-caspase 3 in vivo and in vitro. XL888 attenuated the complex formation of HSP90 and STAT3, leading to decreased expression levels of STAT3 and p-STAT3. In human HCC tissues, IHC scores of HSP90 were positively correlated with those of STAT3. Overexpression of STAT3 rescued cell apoptosis induced by co-treatment of XL888 and heat. SIGNIFICANCE: We implied that XL888 promoted apoptosis of HCC cells induced by heat via disrupting the binding of HSP90 and STAT3, providing theoretical basis for a novel combination strategy for HCC.

Genomic insight into the population history of Central Han Chinese.

BACKGROUND: In recent decades, considerable attention has been paid to exploring the population genetic characteristics of Han Chinese, mainly documenting a north-south genetic substructure. However, the central Han Chinese have been largely underrepresented in previous studies. AIM: To infer a comprehensive understanding of the homogenisation process and population history of Han Chinese. SUBJECTS AND METHODS: We collected samples from 122 Han Chinese from seven counties of Hubei province in central China and genotyped 534,000 genome-wide SNPs. We compared Hubei Han with both ancient and present-day Eurasian populations using Principal Component Analysis, ADMIXTURE, f statistics, qpWave and qpAdm. RESULTS: We observed Hubei Han Chinese are at a genetically intermediate position on the north-south Han Chinese cline. We have not detected any significant genetic substructure in the studied groups from seven different counties. Hubei Han show significant evidence of genetic admixture deriving about 63% of ancestry from Tai-Kadai or Austronesian-speaking southern indigenous groups and 37% from Tungusic or Mongolic related northern populations. CONCLUSIONS: The formation of Han Chinese has involved extensive admixture with Tai-Kadai or Austronesian-speaking populations in the south and Tungusic or Mongolic speaking populations in the north. The convenient transportation and central location of Hubei make it the key region for the homogenisation of Han Chinese.

Hypoxia-autophagy axis induces VEGFA by peritoneal mesothelial cells to promote gastric cancer peritoneal metastasis through an integrin α5-fibronectin pathway.

BACKGROUND: Peritoneal metastasis (PM) is an important pathological process in the progression of gastric cancer (GC). The metastatic potential of tumor and stromal cells is governed by hypoxia, which is a key molecular feature of the tumor microenvironment. Mesothelial cells also participate in this complex and dynamic process. However, the molecular mechanisms underlying the hypoxia-driven mesothelial-tumor interactions that promote peritoneal metastasis of GC remain unclear. METHODS: We determined the hypoxic microenvironment in PM of nude mice by immunohistochemical analysis and screened VEGFA by human growth factor array kit. The crosstalk mediated by VEGFA between peritoneal mesothelial cells (PMCs) and GC cells was determined in GC cells incubated with conditioned medium prepared from hypoxia-treated PMCs. The association between VEGFR1 and integrin α5 and fibronectin in GC cells was enriched using Gene Set Enrichment Analysis and KEGG pathway enrichment analysis. In vitro and xenograft mouse models were used to evaluate the impact of VEGFA/VEGFR1 on gastric cancer peritoneal metastasis. Confocal microscopy and immunoprecipitation were performed to determine the effect of hypoxia-induced autophagy. RESULTS: Here we report that in the PMCs of the hypoxic microenvironment, SIRT1 is degraded via the autophagic lysosomal pathway, leading to increased acetylation of HIF-1α and secretion of VEGFA. Under hypoxic conditions, VEGFA derived from PMCs acts on VEGFR1 of GC cells, resulting in p-ERK/p-JNK pathway activation, increased integrin α5 and fibronectin expression, and promotion of PM. CONCLUSIONS: Our findings have elucidated the mechanisms by which PMCs promote PM in GC in hypoxic environments. This study also provides a theoretical basis for considering autophagic pathways or VEGFA as potential therapeutic targets to treat PM in GC.

GALNT6 promotes breast cancer metastasis by increasing mucin-type O-glycosylation of α2M.

Breast cancer is the most lethal malignancy in women. N-acetylgalactosaminyltransferase 6 (GALNT6) is an enzyme which mediates the initial step of mucin-type O-glycosylation, and has been reported to be involved in mammary carcinogenesis. However, the molecular mechanism of GALNT6 in breast cancer metastasis has not been fully explored. In this study, based on online database analyses and tissue microarrays, the overall survival (OS) of breast cancer patients with high expression of GALNT6 was found to be shorter than those with low expression of GALNT6. Also, high GALNT6 expression was positively correlated with advanced pN stage and pTNM stage. GALNT6 was shown to be able to promote the migration and invasion of breast cancer cells, and enhance the level of mucin-type O-glycosylation of substrates in the supernatants of breast cancer cells. Qualitative mucin-type glycosylomics analysis identified α2M as a novel substrate of GALNT6. Further investigation showed that GALNT6 increased O-glycosylation of α2M, and the following activation of the downstream PI3K/Akt signaling pathway was involved in the promotion of migration and invasion of breast cancer cells. This study identified a new substrate of GALNT6 and provides novel understanding of the role of GALNT6 in promoting metastasis and poor prognosis in breast cancer.

Leucine-rich repeat neuronal protein-1 suppresses apoptosis of gastric cancer cells through regulation of Fas/FasL.

Gastric cancer (GC) is a common cause of cancer-related death worldwide. As a result of the lack of reliable diagnostic or prognostic biomarkers for GC, patient prognosis is still poor. Therefore, there is an urgent need for studies examining the underlying pathogenesis of GC in order to find effective biomarkers. LRRN1 (leucine-rich repeat neuronal protein-1) is a type I transmembrane protein that plays an important role in the process of nerve development and regeneration. However, its role in cancer, especially in GC, remains unclear. In the present study, we found that LRRN1 expression is upregulated in GC tissues and that high LRRN1 expression is associated with poor prognosis. siRNA and shRNA-mediated knockdowns of LRRN1 expression promoted GC cell apoptosis and activation of the Fas/FasL pathway. LRRN1 knockdown also resulted in upregulation of JUN, a subunit of the transcription factor AP-1 (activator protein-1). This suggests that LRRN1 suppresses GC cell apoptosis by downregulating AP-1, resulting in inhibition of the Fas/FasL pathway. These results confirm that LRRN1 plays a significant role in GC pathogenesis. Moreover, LRRN1 may be a potential prognostic biomarker and therapeutic target for GC.

Epidemiologic and genomic insights on mcr-1-harbouring Salmonella from diarrhoeal outpatients in Shanghai, China, 2006-2016.

BACKGROUND: Colistin resistance mediated by mcr-1-harbouring plasmids is an emerging threat in Enterobacteriaceae, like Salmonella. Based on its major contribution to the diarrhoea burden, the epidemic state and threat of mcr-1-harbouring Salmonella in community-acquired infections should be estimated. METHODS: This retrospective study analysed the mcr-1 gene incidence in Salmonella strains collected from a surveillance on diarrhoeal outpatients in Shanghai Municipality, China, 2006-2016. Molecular characteristics of the mcr-1-positive strains and their plasmids were determined by genome sequencing. The transfer abilities of these plasmids were measured with various conjugation strains, species, and serotypes. FINDINGS: Among the 12,053 Salmonella isolates, 37 mcr-1-harbouring strains, in which 35 were serovar Typhimurium, were detected first in 2012 and with increasing frequency after 2015. Most patients infected with mcr-1-harbouring strains were aged <5 years. All strains, including fluoroquinolone-resistant and/or extended-spectrum ß-lactamase-producing strains, were multi-drug resistant. S. Typhimurium had higher mcr-1 plasmid acquisition ability compared with other common serovars. Phylogeny based on the genomes combined with complete plasmid sequences revealed some clusters, suggesting the presence of mcr-1-harbouring Salmonella outbreaks in the community. Most mcr-1-positive strains were clustered together with the pork strains, strongly suggesting pork consumption as a main infection source. INTERPRETATION: The mcr-1-harbouring Salmonella prevalence in community-acquired diarrhoea displays a rapid increase trend, and the ESBL-mcr-1-harbouring Salmonella poses a threat for children. These findings highlight the necessary and significance of prohibiting colistin use in animals and continuous monitoring of mcr-1-harbouring Salmonella.

FUT4 is involved in PD-1-related immunosuppression and leads to worse survival in patients with operable lung adenocarcinoma.

PURPOSE: As an important glycosyltransferase, fucosyltransferase IV (FUT4) is abnormally upregulated in different types of cancers, but its clinical role remains inexplicit. This work aimed to determine the predictive ability of FUT4 in lung adenocarcinoma (LUAD) after curative resection, as well as to explore the role of a possible FUT4 molecular mechanism on LUAD malignant behavior. METHODS: A total of 273 LUAD patients after curative resection with complete clinicopathological and RNAseq data from The Cancer Genome Atlas (TCGA) cohort were collected. Correlation of FUT4 with overall survival (OS) was analyzed based on TCGA and further validated by online "Kaplan-Meier Plotter" database and IHC in 70 LUAD patients recruited in the First Hospital of China Medical University cohort. Multivariate Cox regression analysis and 1000 bootstrapping were performed to verify the predictive value of FUT4. Gene set enrichment assay (GSEA) was performed to investigate the biological characteristics. Correlation between PD-1 and FUT4 was analyzed based on TCGA cohort and validated by IHC on cohort from our hospital. RESULTS: Increased FUT4 expression led to reduced overall survival (OS) of LUAD patients based on TCGA (p = 0.006 and 0.001 for dichotomous and trichotomous modeling, respectively) and externally validated in KMPLOTTER (p = 0.01) and by IHC based on cohort from our hospital (p = 0.005 and p = 0.019 for dichotomous and trichotomous modeling, respectively). FUT4 overexpression was an independent high risk factor for OS along with advanced pT stage and pTNM stage (p = 0.001, p = 0.037, and p < 0.001, respectively). GSEA revealed that FUT4 overexpression might correlate with shortened survival of LUAD patients by promoting cell proliferation via ERBB signaling, and suppressing immune response-related pathways. FUT4 expression positively correlated with PD-1 in TCGA (p = 0.026) and validated by IHC on cohort from our hospital (p = 0.029). CONCLUSIONS: Increased FUT4 expression led to reduced OS in operable LUAD. FUT4 showed significant correlation with immune response and PD-1 expression.

Rapid detection of mcr-1 by recombinase polymerase amplification.

PURPOSE: The plasmid-mediated mcr-1 gene conferring colistin resistance has a strong ability to spread. The objective of this study was to establish a rapid and sensitive recombinase polymerase amplification (RPA) method for plasmid-mediated polymyxin-resistant gene mcr-1 detection. METHODS: Using the reported sequence of the mcr-1 gene, we designed specific primers and probes for RPA. Twenty mcr-1-positive strains carrying IncI2/IncHI2/IncX4/IncP plasmids were screened by RPA in this study. The performance of this new assay was compared to that of PCR, TaqMan probe real-time PCR and SYBR Green-based real-time PCR. RESULTS: Twenty mcr-1-positive samples and three negative samples were tested by RPA and the positive detection rate for the mcr-1-positive samples was 100 %. The detection limit of RPA was approximately 100 fg. Compared with real-time PCR, the RPA assay was more effective due to shorter reaction times, simpler instruments and higher sensitivity, while it had the same high specificity as real-time PCR. CONCLUSION: RPA detection based on the mcr-1 gene was successfully applied in our study. The plasmid-mediated mcr-1 gene conferring colistin drug resistance has a strong ability to spread, suggesting the need to further strengthen the detection of this resistance gene in surveillance. Therefore, we require more sensitive detection methods than have previously been available and the RPA assay established in this study meets these detection needs.

Long non-coding RNA UCA1 upregulation promotes the migration of hypoxia-resistant gastric cancer cells through the miR-7-5p/EGFR axis.

A variety of solid tumors are surrounded by a hypoxic microenvironment, which is known to be associated with high metastatic capability and resistance to various clinical therapies, contributing to a poor survival rate for cancer patients. Although the majority of previous studies on tumor-associated hypoxia have focused on acute hypoxia, chronic hypoxia more closely mimics the actual hypoxic microenvironment of a tumor. In this study, two novel hypoxia-resistant gastric cancer (HRGC) cell lines which could grow normally in 2% oxygen were established. The long non-coding RNA UCA1 was upregulated in HRGC cells, which promoted their migration. Bioinformatics analysis and a luciferase reporter assay showed that miR-7-5p could bind to specific sites of UCA1 to regulate the target EGFR through competitive endogenous RNA function. UCA1 directly interacted with miR-7-5p and decreased the binding of miR-7-5p to the EGFR 3'-untranslated region, which suppressed the degradation of EGFR mRNA by miR-7-5p. Therefore, long-term hypoxia induced UCA1 to promote cell migration by enhancing the expression of EGFR. This study thus reveals a new mechanism by which a hypoxic microenvironment promotes tumor metastasis, and highlights UCA1 as a potential biomarker for predicting the metastasis of gastric cancer to guide clinical treatment.

Cancer-associated fibroblasts-stimulated interleukin-11 promotes metastasis of gastric cancer cells mediated by upregulation of MUC1.

Cancer-associated fibroblasts (CAFs) are major components of the tumor stroma and regulators of tumor progression. However, the molecular mechanism by which CAFs promote gastric cancer progression should be further explored. In our study, we found that interleukin-11 (IL-11) secretion was significantly increased when CAFs were co-cultured with gastric cancer cells. Co-culture system-derived IL-11 promoted the migration and invasion of gastric cancer cells, whereas the increase of migration and invasion was attenuated by a neutralizing antibody of IL-11 or inhibition of JAK/STAT3 and MAPK/ERK pathways with specific inhibitors. Taken together, these results revealed that CAFs play a significant role in the gastric cancer progression in the tumor microenvironment through IL-11-STAT3/ERK signaling by upregulating MUC1. Also, IL-11 targeted therapy can achieve an effective treatment against gastric cancer indirectly by exerting their action on stromal fibroblasts.

CXCL9/10/11, a regulator of PD-L1 expression in gastric cancer.

BACKGROUND: Programmed death-ligand 1 (PD-L1) is an immunosuppressor that plays an important role in cancer treatments. Although majority of the studies demonstrated that PD-L1 expression was regulated by cellular intrinsic and extrinsic controls, and IFN-γ was a key molecule of extrinsic control, other studies imply that other cytokines play important roles in PD-L1 expression. In this study, we investigated the regulation of PD-L1 by chemokine signaling pathway in gastric cancer (GC) cells. METHODS: Bioinformatics was used to explore the PD-L1-related genes in GC and propose a hypothesis. PD-L1 and CXCR3 expression were detected by western blot in SGC7901 and MKN74 cell lines. Meanwhile, PD-L1 and CXCR3 expressions were immunohistochemically assessed for their relevance. Moreover, PD-L1, pSTAT3 and pAkt were detected after treatment with CXCL9/10/11. Furthermore,PD-L1, pSTAT3 and pAkt were evaluated after blocking chemokine signaling in SGC7901 cells. RESULTS: Based on online database analysis, CXCL9/10/11-CXCR3 is proposed to upregulate PD-L1 expression by activating the STAT and PI3K-Akt pathways. This hypothesis was confirmed by in vitro and vivo experiments. CXCR3 and PD-L1 were expressed in GC cell lines and tissues, and the expression of CXCR3 and PD-L1 was positively related. PD-L1 was upregulated after treatment with CXCL9/10/11, accompanied by activation of STAT3 and Akt. After blocking chemokine signaling, upregulation of PD-L1 and activation of STAT3 and Akt were diminished. CONCLUSIONS: CXCL9/10/11-CXCR3 upregulated the expression of PD-L1 by activating the STAT and PI3K-Akt signaling pathways in GC cells. There was a significant positive correlation between the expression of PD-L1 and CXCR3 in gastric cancer patient tissues.

The Chemokine Receptor CXCR4 and c-MET Cooperatively Promote Epithelial-Mesenchymal Transition in Gastric Cancer Cells.

The C-X-C motif chemokine receptor 4 (CXCR4) pathway can promote tumor metastasis but is dependent on cross talk with other signaling pathways. The MET proto-oncogene (c-MET) participates in metastasis and is highly expressed in gastric cancer. However, the relationship between CXCR4 and c-MET signaling and their mechanisms of action in gastric cancer metastasis remain unclear. In this study, in vitro experiments demonstrated that C-X-C motif chemokine ligand 12 (CXCL12)/CXCR4 induces epithelial-mesenchymal transition (EMT) and promotes migration in gastric cancer cells, which is accompanied by c-MET activation. These phenomena were reversed by c-MET inhibition. Further investigation revealed that c-MET activation correlated with its interaction with caveolin 1 in lipid rafts, induced by CXCL12. In clinical samples, we observed a significant positive association between CXCR4 expression and c-MET phosphorylation (r = 0.259, P = .005). Moreover, samples expressing both receptors were found to indicate significantly poorer patient prognosis (P < .001). These results suggest that CXCL12 induces EMT at least partially through cross talk between CXCR4 and c-MET signaling. In addition, changes in these pathways could have clinical importance for the treatment of gastric cancer.

4-Phenybutyric acid promotes gastric cancer cell migration via histone deacetylase inhibition-mediated HER3/HER4 up-regulation.

Dysregulation of histone acetylation plays an important role in tumor development. Histone acetylation regulates gene transcription and expression, which is reversibly regulated by histone acetyltransferase (HAT) and histone deacetylase (HDAC). As an HDAC inhibitor, 4-phenylbutyric acid (4-PBA) can increase histone acetylation levels by inhibiting HDAC activity. While 4-PBA inhibits proliferation of tumor cells in vitro, clinical trials have failed to show benefits of 4-PBA for refractory solid tumors. Here, we found that 4-PBA could enhance the migration capacity of gastric cancer cells. Upregulation of HER3/HER4 and activation of HER3/HER4-ERK pathway was shown to be involved in 4-PBA-induced gastric cancer cell migration. Knockdown of HER3/HER4 blocked HER3/HER4-ERK activation and partially prevented 4-PBA-induced cell migration. Consistently, the ERK inhibitor PD98059 also partially prevented 4-PBA-induced cell migration. Moreover, enhanced levels of acetyl-histones were detected following 4-PBA-treatment, and histone3 acetylation in promoter regions of HER3 and HER4 were confirmed by ChIP. These results demonstrate that 4-PBA promotes gastric cancer cells migration through upregulation of HER3/HER4 subsequent to increased levels of acetyl-histone and activation of ERK signaling. These novel findings provide important considerations for the use of 4-PBA in cancer therapeutics.

Chk1 activation attenuates sensitivity of lapatinib in HER2-positive gastric cancer.

The ATM and Rad3-related (ATR)/checkpoint kinase 1 (Chk1) pathway plays a pivotal role in DNA damage sensor and modulating homologous recombination. Recently, emerging evidence demonstrated that Chk1 phosphorylation was associated with chemotherapy and radiotherapy resistance. In this study, we explored the effect of ATR/Chk1 pathway on regulating lapatinib sensitivity in human epidermal growth factor receptor-2 (HER2)-positive gastric cancer cell lines. We selected two HER2-positive gastric cancer cell lines, and NCI-N87 cells exhibited higher sensitivity than MKN7 cells. Application of lapatinib inhibited phosphorylated HER2 and EGFR and the formation of epidermal growth factor receptor (EGFR)/HER2 complex in both cells. In NCI-N87 cells, lapatinib induced G1 arrest and reduced Chk1 phosphorylation through inhibiting the expression of DNA topoisomerase 2-binding protein 1 (TopBP1). While in MKN7 cells, no significant cell cycle transition was found and phosphorylated Chk1 was mildly upregulated. Inhibition of Chk1 phosphorylation enhanced the lapatinib sensitivity of MKN7 cells, which was shown by potentiated anti-proliferative effect, G1 arrest, downregulation of phosphorylated AKT and ERK along with aggravated DNA damage. In addition, increased Chk1 phosphorylation in NCI-N87 cells attenuated lapatinib-induced anti-proliferative effect and G1 arrest, and abrogated reduced phosphorylated AKT and ERK. Taken together, our study provides a novel mechanism for regulating lapatinib sensitivity in HER2 positive gastric cancer cells, suggesting a new strategy in clinical treatment.