The METTL3-m6A-YTHDC1-AMIGO2 axis contributes to cell proliferation and migration in esophageal squamous cell carcinoma.

The upregulation of methyltransferase-like 3 (METTL3) has been associated with the progression of esophageal cancer. However, METTL3-induced N6-methyladenosine (m6A) alterations on the downstream target mRNAs in esophageal squamous cell carcinoma (ESCC) are not yet fully understood. Our study revealed that silencing METTL3 resulted in a significant decrease in ESCC cell proliferation and metastasis in vitro and in vivo. Additionally, the adhesion molecule with Ig like domain 2 (AMIGO2) was identified as a potential downstream target of both METTL3 and YTH Domain-Containing Protein 1 (YTHDC1) in ESCC cells. Functionally, AMIGO2 augmented the malignant behaviors of ESCC cells in vitro and in vivo, and its overexpression can rescue the inhibition of the proliferation and migration in ESCC cells induced by METTL3 or YTHDC1 knockdown. Furthermore, our findings revealed that knockdown of METTL3 decreased m6A modification in the 5'-untranslated regions (5'UTR) of AMIGO2 precursor mRNA (pre-mRNA), and YTHDC1 interacted with AMIGO2 pre-mRNA to regulate AMIGO2 expression by modulating the splicing process of AMIGO2 pre-mRNA in ESCC cells. These findings highlighted a novel role of the METTL3-m6A-YTHDC1-AMIGO2 axis in regulating ESCC cell proliferation and motility, suggesting its potential as a therapeutic target for ESCC.

Ferroptosis involves in Schwann cell death in diabetic peripheral neuropathy.

Accumulating evidence shows that Schwann cells' (SCs) death caused by high glucose (HG) is involved in the pathological process of diabetic peripheral neuropathy (DPN). Ferroptosis is a novel form of regulatory cell death driven by iron-dependent lipid peroxidation. However, it is not clear whether ferroptosis is involved in the death process of SCs induced by HG. The expression of ferroptosis-related indicators in the serum of DPN patients was detected by ELISA. Subsequently, using cell counting kit­8, western blot, real-time PCR, and Ki-67 staining, we investigated the effects of HG on the ferroptosis of SCs and initially explored the underlying mechanism. The results showed that the serum levels of glutathione peroxidase 4 (GPX4) and glutathione in patients with DPN decreased, while malondialdehyde levels increased significantly. Then, we observed that erastin and HG induced ferroptosis in SCs, resulting in the decrease in cell activity and the expression level of GPX4 and SLC7A11, which could be effectively reversed by the ferroptosis inhibitor Fer-1. Mechanistically, HG induced ferroptosis in SCs by inhibiting the NRF2 signaling pathway. Our results showed that ferroptosis was involved in the death process of SCs induced by HG. Inhibition of ferroptosis in SCs might create a new avenue for the treatment of DPN.

Apigenin regulates the migration, invasion, and autophagy of hepatocellular carcinoma cells by downregulating YAP.

Apigenin is an edible flavonoid with anticancer properties; however, the underlying mechanisms in hepatocellular carcinoma (HCC) remain to be clarified. In the present study, we demonstrated that apigenin decreased the viability of both SMMC-7721 and SK-Hep1 cells in a dose-dependent manner, and inhibited the migration and invasion of HCC cells with different metastatic potential by regulating actin cytoskeletal rearrangements. Moreover, we showed that apigenin decreased the expression of YAP, and subsequently reduced migration and invasion by modulating the expression of the epithelial-mesenchymal transition (EMT) markers, and promoted the autophagy of HCC cells by regulating the expression of autophagy-related genes. Collectively, the present findings might provide a novel mechanism for the therapeutic application of apigenin in HCC.

Emerin knockdown induces the migration and invasion of hepatocellular carcinoma cells by up-regulating the cytoplasmic p21.

Emerin (EMD) plays diverse roles in cellular polarity organization, nuclear stability, and cell motility, however, the biological role of EMD relevant to the migration and invasion of hepatocellular carcinoma (HCC) cells has not yet been illustrated. In the present study, we initially found that the upregulation of EMD in HCC tissues, and EMD expression was negatively correlated with the spontaneous metastatic potential of HCC cell lines. Loss of EMD in HCC cells facilitated cell migration and invasion in vitro and metastasis in vivo. Meanwhile, we demonstrated that EMD knockdown induced EMT but enhanced p21 expression in HCC cells. Notably, silencing of EMD in HCC cells increased the cytoplasmic localization of p21 protein, whereas p21 knockdown partially abrogated the migratory and invasive ability, EMT, and the actin cytoskeleton rearrangement induced by EMD knockdown in HCC cells. Our results indicated a significant role of EMD knockdown in the HCC cell motility and metastasis through upregulating the cytoplasmic p21, unveiling a novel mechanism of cell motility regulation induced by EMD.

Calmodulin activation of polo-like kinase 1 is required during mitotic entry.

Polo-like kinase 1 (Plk1) is a conserved key regulator of the G2/M transition, but its upstream spatiotemporal regulators remain unknown. With the help of immunofluorescence, co-immunoprecipitation, and glutathione S-transferase (GST) pull-down assay, we found that calmodulin (CaM) is one such regulatory molecule that associates with Plk1 from G2 to metaphase. More importantly, this interaction results in considerable stimulation of Plk1 kinase activity leading to hyperphosphorylation of Cdc25C. Our results provide new insight into the role of CaM as an upstream regulator of Plk1 activation during mitotic entry.

Growth-inhibitory effects of MOB2 on human hepatic carcinoma cell line SMMC-7721.

AIM: To investigate the growth-inhibiting and apoptosis-inducing effects of the gene MOB2 on human hepatic carcinoma cell line SMMC-7721. METHODS: The full-length cDNA of the MOB2 gene was amplified from human umbilical vein endothelial cells. The correct full-length MOB2 cDNA was subcloned into the eukaryotic expression vector pEGFP-C1. After lipofection of the MOB2 gene into cancer cells, the levels of MOB2 protein in the cancer cells were detected by immunoblotting. To transfect the recombined plasmid vector pEGFP-CI-MOB2 into SMMC-7721 cells, the cells were cultured in Dulbecco's Modified Eagle's Medium with 10% fetal calf serum and glutamine, and then mixed with liposomes, Lipofectamine 2000 and the plasmid vector pEGFP-CI-MOB2. RESULTS: We observed the growth and proliferation of SMMC-7721 cells containing pEGFP-CI-MOB2 and analyzed their apoptosis and growth cycle phases by flow cytometry. We successfully transfected the recombined plasmid vector pEGFP-CI-MOB2 into SMMC-7721 cells and screened for a single clone cell containing MOB2. After transfection, MOB2 enhanced growth suppression, induced apoptosis, increased the ratio of G0/G1, significantly inhibited the advance of cell cycle phase, and arrested cells in G0/G1 phase. CONCLUSION: MOB2 overexpression induces apoptosis and inhibits the growth of human hepatic cancer cells, which may be useful in gene therapy for hepatic carcinoma.

[Effect of genistein on MAPK signal pathway in the collagen-induced arthritis fibroblast-like synoviocytes].

OBJECTIVE: To study the effect of genistein (Gen) on MAPK signal pathway in the CIA rat fibroblast-like synoviocytes (FLS). METHODS: The rat model of collagen-induced arthritis (CIA) was established. The cultured FLS of CIA rats were divided using randomized method. The effects of Gen (at the concentration of 50, 100, and 200 micromol/L, respectively) on the proliferation of FLS in CIA rats using methyl thiazolyl tetrazolium (MTT) assay. Effects of Gen (at the concentration of 50, 100, and 200 pmol/L, respectively) on the expressions of extracellular signal-regulated kinase (ERK) and phosphorylated extracellular signal-regulated kinase (p-ERK) in the FLS of CIA rats were detected. RESULTS: Gen could inhibit the proliferation of FLS in CIA rats. The FLS proliferation in the high dose Gen group at 72 h was only 1.10+/-0.04, significantly lower than that in the model group (2.12+/-0.03, P<0.01). Besides, after Gen's action on FLS, the expression of p-ERK was down-regulated. It was only 0.34+/-0.02 in the high dose Gen group, significantly lower than that in the model group (2.68+/-0.14, P<0.01). There was no change in the expression of ERK (P>0.05). CONCLUSIONS: Gen could inhibit the proliferation of FLS in CIA rats. Its mechanism of action was mainly correlated to down-regulating the tyrosine kinase of MAPK signal transduction pathway and inhibiting phosphorylation of ERK.

Synergistic antitumor effects of in vivo production of human endostatin and tissue inhibitor of metalloproteinase-1 in mice after subcutaneous implantation of primary fibroblasts transfected by adenovirus-mediated gene delivery.

BACKGROUND: Tissue inhibitor of metalloproteinase (TIMP)-1 is a multifunctional protein. The aim of the study was to examine the feasibility of using a combination of adenovirus-mediated gene delivery of TIMP-1 plus endostatin and cell transplantation techniques to treat tumor growth and metastasis in mouse melanoma. METHODS: A enzyme-linked immunosorbent assay (ELISA) was used to detect the level of TIMP-1 and endostatin in vitro and in vivo. A tumor bearing mouse model and an experimental lung metastasis model in animal experiments were used to explore the therapeutic effect of in vivo production of human TIMP-1 and endostatin after the implantation of primary fibroblasts infected with the indicated adenovirus into tumor-bearing mice and a cytochemical method was used to observe histopathological changes of the tumor. An experimental lung metastasis model was established by injecting B16BL6 cells into the tail vein of mice and adenovirus-infected primary fibroblasts were subcutaneously implanted into the mice 24 hours later. Twenty-one days after tumor cell injection, mice were sacrificed to examine the effect on nodules visible as black forms on the surface of the lungs in B16BL6 cells. RESULTS: TIMP-1 and endostatin were secreted into the supernatants of cultures of Ad-TIMP-1 and Ad-End-infected mouse primary fibroblasts. We also observed that implantation of fibroblasts infected with Ad-TIMP-1 alone, Ad-End alone, or Ad-TIMP-1 plus Ad-End resulted in detectable blood levels which may clearly inhibit the tumor growth and metastasis in a murine melanoma model. CONCLUSION: These results suggest the high capacity of transfection for the delivery of TIMP-1 or endostatin gene constructs into primary fibroblasts, and demonstrate that the implantation of TIMP-1 and endostatin producing fibroblasts at a site in vivo where direct secretion of TIMP-1 and endostatin into the blood is possible represented a promising approach for the development of cancer therapy.

[Inhibitory effect of genistein on hypoxia-inducible factor-1alpha expression induced by cobalt chloride in leukemia cell line K562].

This study was aimed to investigate the effect of genistein (gen) on the expression of hypoxia inducible factor-1alpha (HIF-1alpha) induced by cobalt chloride (CoCl(2)) in human leukemia cell line K562. The hypoxia condition was simulated by CoCl(2); the dose- and time-effect groups were prepared as follows: the former were exposed to 0, 50, 100 and 150 micromol/L of CoCl(2) for 72 hours, the latter were detected at 0, 24, 48 and 72 hours while treated with CoCl(2) 100 micromol/L. The gen-treated samples were divided into five groups: (1) normal control; (2) CoCl(2) 150 micromol/L; (3) CoCl(2) 150 micromol/L + gen 50 micromol/L; (4) CoCl(2) 150 micromol/L + gen 100 micromol/L; (5) CoCl(2) 150 micromol/L + gen 200 micromol/L. The HIF-1alpha mRNA and protein were detected by RT-PCR and Western blot respectively. The results indicated that the expression of HIF-1alpha protein in K562 cells induced by CoCl(2) increased in dose-and time-dependent manner (p<0.01), while the expression of HIF-1alpha mRNA in K562 cell remained the similar level (p>0.05). Gen significantly inhibited the expression of HIF-1alpha protein induced by CoCl(2) in dose-dependent manner (p<0.01) while the HIF-1alpha mRNA expression was not affected by treatment of gen (p>0.05). It is concluded that CoCl(2) dose- and time-dependently induced the HIF-1alpha protein expression; HIF-1alpha mRNA was constantly expressed regardless of normoxic conditions or in the presence of cobalt ion under normoxic conditions. Gen can inhibit HIF-1alpha expression in K562 cell induced by CoCl(2) at level of protein, but not mRNA.

[Effects of arsenic trioxide on expressions of vascular endothelial growth factor and P-glycoprotein in multidrug resistant leukemia cell line K562/A02].

OBJECTIVE: To investigate the effects of arsenic trioxide (ATO) on the expressions of vascular endothelial growth factor (VEGF) and P-glycoprotein (P-gp) in K562/A02 cells and to explore the correlation between VEGF and P-gp. METHODS: The inhibition rate of K562/A02 cell proliferation was detected by using methyl thiazolyl tetrazolium assay (MTT); the level of VEGF was detected by enzyme-linked immunosorbent assay (ELISA) and the expression rate of P-gp was determined by flow cytometry (FCM). RESULTS: 0.05 micromol/L ATO had no influences on the cell proliferation and the expression of VEGF in K562/A02 cells; 0.4 and 3.2 micromol/L ATO could significantly inhibit the K562/A02 cell proliferation and down-regulate the expression of VEGF in K562/A02 cells (P<0.05). The expression of P-gp did not changed after being exposed to 0.05 and 0.4 micromol/L ATO for 24, 48 and 72 hours (P>0.05). 3.2 micromol/L ATO could remarkably reduce the expression of P-gp in K562/A02 cells after 48- and 72-hour incubation with ATO (P<0.05). CONCLUSIONS: The down-regulation of P-gp and VEGF after being exposed to ATO probably contributes to the reversion of multidrug resistance in K562/A02 cells. The level of VEGF may be related to the expression rate of P-gp in K562/A02 cells.

[Effect of arsenic trioxide on VEGF/R and MMP-2, 9 expressed in K562 cells].

OBJECTIVE: To explore the effect of arsenic trioxide (As2 O3) on the level of VEGF, VEGFR and the activity of MMP-2, 9 in K562 cells. METHODS: The inhibition ratio of K562 cell was detected by MTT assay, the level of VEGF by Enzyme-linked immunosorbent assay (ELISA), the expression ratio of VEGFR by flow cytometry (FCM), and the activity of MMP-2, 9 by gelatin zymography assay. RESULTS: (1) The IC50 of K562 cells was (2.12 +/- 0.11) micromol/L. Proliferation of K562 cells was significantly inhibited at the concentration of 0.4 - 6.4 micromol/L As2 O3 (P < 0.05). (2) The expression of VEGF was slightly up-regulated by 0.05 micromol/L As2 O3 (P > 0.05) and prominently inhibited by 0.4 micromol/L and 3.2 micromol/L As2 O3 (P < 0.05). As2 O3 had no influence on VEGFR. (3) The activity of MMP-2 and 9 was partly inhibited by 0.05 micromol/L As2 O3 incubated 72 hours and by 0.4, 3.2 micromol/L, As2 O3. With the increase of As2 O3 concentration and the incubation time, the inhibited effect on MMP-2 and 9 was enhanced. CONCLUSIONS: As2 O3 may down-regulate the expression of VEGF and inhibit the activity of MMP-2 and 9.

Melanoma-associated antigen family protein-D1 regulation of tumor cell migration, adhesion to endothelium, and actin structures reorganization in response to hypoxic stress.

Melanoma-associated antigen family protein-D1 (MAGE-D1) is a recently identified p75 neurotrophin receptor intracellular binding protein and functions as an adaptor that mediates multiple signaling pathways, including Dlx/Msx-mediated transcription. Here, a new regulatory function for MAGE-D1 in tumor cell motility and adhesion to endothelium is described. MAGE-D1 over-expression suppressed HeLa cell and BEL7402 cell migration, invasion, and adhesion to the monolayer of ECV304 cells. We also report that MAGE-D1 over-expression disrupted actin cytoskeleton rearrangement induced by hypoxia and down-regulated hypoxia inducible factor 1-dependent luciferase gene expression. These findings provide new insight into the ability of MAGE-D1 to suppress the motility and adhesion response of tumor cells by interfering with actin cytoskeleton reorganization and hypoxia inducible factor 1-dependent gene expression.

Calmodulin is essential for angiogenesis in response to hypoxic stress in endothelial cells.

Angiogenesis, the formation of new blood vessels that is regulated by hypoxia, is a critical process for the growth and spread of tumors. Multiple phases of this process, including migration, adhesion, and formation of new capillary tubes, are needed for optimal tumor growth. Here, a new regulatory function for Ca2+-CaM in the vascular endothelium is described. Ca2+-CaM activation induced by hypoxia in endothelial cells is essential for angiogenic cellular responses. Inhibition of Ca2+-CaM activity suppressed endothelial cell migration, adhesion on collagen I substrate, invasion and impaired in vitro endothelial cell differentiation into tube-like structures. We also reported that CaM is co-distributed with the actin structures in the lamellipodia in migrating cells, whereas the actin cytoskeleton rearrangement induced by hypoxia was disrupted and HIF-1 transcriptional activity was decreased when treated with CaM antagonists into cultures. These data indicate that Ca2+-CaM activation is more closely associated with the regulation of angiogenic key events, especially in response to hypoxic stress.

Inhibition of adenovirus-mediated human MAGE-D1 on angiogenesis in vitro and in vivo.

MAGE-D1 is a member of the MAGE family of proteins, and functions as an adaptor that mediates multiple signaling pathways. The current study for the first time provides evidence for a role of MAGE-D1 in the negative regulation of angiogenic activity in vitro and in vivo models. Our findings showed that MAGE-D1 over-expression significantly suppressed the angiogenic key events such as endothelial cell migration and invasion, adhesion on collagen I substrate, and in vitro differentiation into tube-like structures under both normoxic and hypoxic conditions. MAGE-D1 over-expression also inhibited in vivo angiogenesis in Matrigel plugs that were implanted subcutaneously in mice. With further experiments, we revealed that MAGE-D1 over-expression disrupted actin cytoskeleton organization and lamellipodia formation, and down-regulated HIF-1-dependent gene expression in endothelial cells under hypoxic conditions. These findings demonstrate a new function of MAGE-D1 in the regulation of angiogenesis and provide new insight into the ability of MAGE-D1 to suppress the growth and angiogenic response of endothelial cells by interfering with HIF-1-dependent gene expression, and actin cytoskeleton reorganization, suggesting that MAGE-D1 might be a novel inhibitor of angiogenesis in vitro and in vivo.

[Inhibitory effects of Scutellaria barbatae D. Don on tumor angiogenesis and its mechanism].

BACKGROUND & OBJECTIVE: Various chemically synthetic anti-angiogenesis agents have serious side effects. The traditional Chinese medicine has attracted considerable attention because of its low toxicity. This study was to explore the inhibitory effects of Scutellaria barbatae D. Don, a kind of traditional Chinese medicinal anti-cancer herb, on tumor angiogenesis, and investigate its mechanism. METHODS: Matrigel plug and human umbilical vascular endothelial cells (HUVECs) were used to construct in vivo and in vitro models of angiogenesis to assess the effect of Scutellaria barbatae D. Don on angiogenesis. After cultured with Scutellaria barbatae D. Don, the migration of endothelial cells was examined by Transwell chamber; the expression of vascular endothelial growth factor (VEGF) in HeLa cells was detected by enzyme-linked immunosorbent assay (ELISA). RESULTS: Scutellaria barbatae D. Don significantly inhibited angiogenesis in Matrigel; the tube formation number was significantly lower in 20% and 40% medicated serum groups containing Scutellaria barbatae D. Don than in 20% and 40% drug-free serum groups (5.6+/-1.1 vs. 9.8+/-1.3, P=0.001; 1.0+/-0.7 vs. 13.4+/-1.1, P<0.001). Migrated endothelial cells was significantly fewer in 20% and 40% medicated serum groups containing Scutellaria barbatae D. Don than in 20% and 40% drug-free serum groups (19.75+/-2.63 vs. 24.25+/-2.06, P=0.038; 14.00+/-2.58 vs. 26.5+/-4.65, P=0.006). When treated for 24 h and 48 h, the expression of VEGF in HeLa cells was significantly lower in 40% medicated serum group containing Scutellaria barbatae D. Don than in 40% drug-free serum group (138.67+/-9.50 vs. 195.82+/-2.43, P=0.006; 93.84+/-41.11 vs. 193.68+/-18.37, P=0.036). CONCLUSION: Scutellaria barbatae D. Don could efficiently inhibit angiogenesis in tumor tissue which might relate with inhibition of endothelial cell migration and down-regulation of VEGF in tumor cells.

Knockdown of c-Met by adenovirus-delivered small interfering RNA inhibits hepatocellular carcinoma growth in vitro and in vivo.

c-Met is highly expressed and constitutively activated in various human tumors. We employed adenovirus-mediated RNA interference technique to knock down c-Met expression in hepatocellular carcinoma cells and observed its effects on hepatocellular carcinoma cell growth in vitro and in vivo. Among the five hepatocellular carcinoma and one normal human liver cell lines we analyzed, c-Met was highly expressed and constitutively tyrosine phosphorylated in only MHCC97-L and HCCLM3 hepatocellular carcinoma cells. Knockdown of c-Met could inhibit MHCC97-L cells proliferation by arresting cells at G0-G1 phase. Soft agar colony formation assay indicated that the colony forming ability of MHCC97-L cells decreased by approximately 70% after adenovirus AdH1-small interfering RNA (siRNA)/met infection. In vivo experiments showed that adenovirus AdH1-siRNA/met inhibited the tumorigenicity of MHCC97-L cells and significantly suppressed tumor growth when injected directly into tumors. These results suggest that knockdown of c-Met by adenovirus-delivered siRNA may be a potential therapeutic strategy for treatment of hepatocellular carcinoma in which c-Met is overexpressed.

RNA interference and its current application in mammals.

OBJECTIVE: The aim of this review was to assess RNA interference (RNAi) and its possibility as a potential and powerful tool to develop highly specific double-stranded RNA (dsRNA) or small interfering RNA (siRNA) based gene-silencing therapeutics. DATA SOURCES: The data used in this review were obtained from the current RNAi-related research reports. STUDY SELECTION: dsRNA-mediated RNAi has recently emerged as a powerful reverse genetic tool to silence gene expression in multiple organisms. The discovery that synthetic duplexes of 21 nucleotides siRNAs trigger gene-specific silencing in mammalian cells has further expanded the utility of RNAi in to the mammalian system. DATA EXTRACTION: The currently published papers reporting the discovery and mechanism of RNAi phenomena and application of RNAi on gene function in mammalian cells were included. DATA SYNTHESIS: Since the recent development of RNAi technology in the mammalian system, investigators have used RNAi to elucidate gene function, and to develop gene-based therapeutics by delivery exogenous siRNA or siRNA expressing vector. The general and sequence-specific inhibitory effects of RNAi that will be selective, long-term, and systemic to modulate gene targets mentioned in similar reports have caused much concern about its effectiveness in mammals and its eventual use as a therapeutic mordality. CONCLUSIONS: It is certain that the ability of RNAi in mammals to silence specific genes, either when transfected directly as siRNAs or when generated from DNA vectors, will undoubtedly accelerate the study of gene function and might also be used as a potentially useful method to develop highly gene-specific therapeutic methods. It is also expected that RNAi might one day be used to treat human diseases.