Weiliang Zhu

The role of N-acetylglucosaminyltransferases V in the malignancy of human hepatocellular carcinoma.

To investigate the role of N-acetylglucosaminyltransferases V (GnT-V) in the malignancy of human hepatocellular carcinoma (HCC), the GnT-V stably suppressed cell line HepG2 GnT-V/1564 was constructed from HepG2. The proliferation, migration, invasion, metastasis of HepG2 GnT-V/1564 was investigated both in vitro and in vivo. The clinical pathological significance of GnT-V expression was also studied in 140 cases of HCC tissues. This study showed that down-regulation of GnT-V inhibited the proliferation, migration and invasion of the HepG2 cells. In addition, GnT-V expression was shown in 138 cases of 140 (98.6%) HCC samples, in 3 cases of 31 (9.7%) in liver cirrhosis cases and in 1 cases of 20 (5.0%) in normal liver tissues. Besides, a higher level of GnT-V was observed more frequently in the advanced tumors with higher T stage and histological grade. These data suggested that GnT-V expression was positively related with malignancy in HCC and GnT-V may be both a differentiation marker and a potential target for the treatment of HCC.

Tyrosine kinase Etk/BMX protects nasopharyngeal carcinoma cells from apoptosis induced by radiation.

Etk (Epithelial and endothelial tyrosine kinase), also known as Bmx (bone marrow X kinase) plays an important role in apoptosis of cancer cells. The purpose of this study was to investigate whether Etk/Bmx is involved in the apoptosis induced by irradiation in NPC cells and correlated with the apoptosis associated proteins such as p53, Bcl-2, Bcl-XL and Bak. To this end, we first developed a NPC subline (SUNE1-Etk) by transfection. The SUNE1-Etk that over-expresses Etk/BMX and its parental SUNE1 cell line were used to confirm whether Etk/BMX can protect NPC cells from apoptosis induced by radiation. The proliferation rates or the level of cell survival following irradiation were assessed by MTT and flow cytometry. Tumorigenecity study was done to substantiate the results in vitro. The results showed that the cell viability was significantly higher in SUNE1-Etk cells than that in parental SUNE1 cells in vitro, and tumors inoculated with SUNE1-Etk cells grew rapidly than those with SUNE1 after irradiation treatment. Our data also demonstrated that the up-expression of Etk/BMX increased G2/M arrest in response to irradiation. The protein level of p53 was greatly down-regulated whereas Bcl-2 was up-regulated, after irradiation treatment of SUNE1-Etk cells. Our results suggested that Etk/BMX may play a role in protection of NPC cells from apoptosis, and both p53 and Bcl-2 may be involved in radiation-induced apoptosis through Etk/Bmx pathway in NPC cells.

MiR-335 regulates the chemo-radioresistance of small cell lung cancer cells by targeting PARP-1

The role of miR-335 in the regulation of chemosensitivity and radiosensitivity of small cell lung cancer (SCLC) was investigated. miR-335 was significantly downregulated in multi-drug-resistant SCLC H69AR and H446DDP cells compared with parental cells as detected by qRT-PCR. Then, we demonstrated the negative correlation between miR-335 expression and the chemo-radiosensitivity of SCLC cells, including cell proliferation, cell clonality and cell apoptosis. In addition, miR-335 overexpression inhibited cell migration in vitro and tumor growth in vivo, whereas inhibition of miR-335 promoted cell migration and tumor growth. The underlying mechanism was further studied. Poly [ADP-ribose] polymerase 1 (PARP-1) was identified as a direct target gene of miR-335 in SCLC by bioinformatics analysis and validated via luciferase reporter assay. Overexpression of miR-335 decreased the expression of PARP-1 mRNA and protein, and NF-κB protein levels were correspondingly downregulated, thus regulating the chemo-radiosensitivity of SCLC. Taken together, these findings indicate that miR-335 may serve as a critical regulator of chemo-radiotherapy resistance in SCLC and a new potential therapeutic target.

Down-regulation of GnT-V enhances nasopharyngeal carcinoma cell CNE-2 radiosensitivity in vitro and in vivo

The purpose of this study was to investigate the role of GnT-V on radiosensitivity in human nasopharyngeal carcinoma (NPC) both in vitro and in vivo, and the possible mechanism. The GnT-V stably suppressed cell line CNE-2 GnT-V/2224 was constructed from CNE-2 by transfection. The radiosensitivity of the cells was studied by CCK-8 assay, flow-cytometry, caspases-3 activity analysis and tumor xenografts model. The expression of Bcl-2, Bax and Bcl-xl was analyzed with or without radiation. The results showed that down-regulation of GnT-V enhanced CNE-2 radiosensitivity. The underlying mechanisms may be link to the cell cycle G2-M arrest and the reduction of Bcl-2/Bax ratio. The results suggest that GnT-V may be a potential target for predicting NPC response to radiotherapy.

N‐acetylglucosaminyltransferase V modulates radiosensitivity and migration of small cell lung cancer through epithelial–mesenchymal transition

N‐acetylglucosaminyltransferase V (Gnt‐V) has been linked to the migration of various human cancers. Recently we have found that inhibition of Gnt‐V increases the radiosensitivity of cancer cells. However, the mechanisms by which Gnt‐V mediates radiosensitivity and migration, especially in small cell lung cancer (SCLC) remain unknown. In our study, two SCLC cell lines (H1688 and H146) were used to investigate whether Gnt‐V modulated the radiosensitivity and migration of SCLC cells through the epithelial–mesenchymal transition (EMT). The results showed that the expression of Gnt‐V correlated with the N stage in patients with SCLC. Overexpression of Gnt‐V led to a further increase in the relative viable cell number and survival fraction with a decrease in apoptosis rate and Bax/Bcl‐2 ratio, when the cells were treated with irradiation. By contrast, knockdown of Gnt‐V with irradiation resulted in a further decrease in the relative viable cell number and survival fraction but an increase in apoptosis rate and Bax/Bcl‐2 ratio. Cells expressing high levels of Gnt‐V increased migration whereas low levels of Gnt‐V suppressed cell migration. Besides, the transient knockdown of ZEB2 led to an increase in radiosensitivity and an inhibition in the migration of SCLC cells. Furthermore, Gnt‐V was negatively correlated with E‐cadherin expression but positively correlated with N‐cadherin, vimentin and ZEB2 expression. Finally, an in vivo study revealed that upregulation of Gnt‐V caused tumour growth more quickly, as well as the expression of EMT‐related markers (N‐cadherin, vimentin and ZEB2). Taken together, the study suggested that an elevation of Gnt‐V could lead to the radiosensitivity and migration of SCLC cells by inducing EMT, thereby highlighting Gnt‐V as a potential therapeutic target for the prevention of EMT‐associated tumour radioresistance and migration.

Down-regulation of GnT-V inhibits nasopharyngeal carcinoma cell CNE-2 malignancy in vitro and in vivo.

To investigate the role of N-acetylglucosaminyltransferases V (GnT-V) in the development of human nasopharyngeal carcinoma (NPC) both in vitro and in vivo, the GnT-V stably suppressed cell line CNE-2 GnT-V/2224 was constructed from CNE-2. The studies indicated that down-regulation of GnT-V inhibited the proliferation, migration and invasion abilities of the NPC cell line CNE-2. The radio sensitivity of CNE-2 was enhanced after down-regulation of GnT-V, which may be associated with the decreased expression of bcl-2.

Overexpression of interferon regulatory factor 7 (IRF7) reduces bone metastasis of prostate cancer cells in mice.

The purpose of this study was to identify the role of interferon regulatory factor 7 (IRF7) in the bone metastasis of prostate cancer. Herein we demonstrated the lower expression of IRF7 in bone metastases of prostate cancer. Overexpression of IRF7 in prostate cancer cells had a marked effect on inhibiting bone metastases but not on tumor growth in xenograft nude mice. While in vitro, upregulation of IRF7 had little effect on the malignant phenotype of prostate cancer cells including proliferation, apoptosis, migration, and invasion. However, prostate cancer cells overexpressing IRF7 significantly enhanced the activity of NK cells, which resulted in the cytolysis of prostate cancer target cells. The underlying mechanism may be relevant to the increasing expression of IFN-β induced by IRF7, as the downregulation of which could inversely inhibit the activity of NK cells. In conclusion, our findings indicate that IRF7 plays a role in reducing bone metastasis of prostate cancer by IFN-β-mediated NK activity.

TSPAN12 promotes chemoresistance and proliferation of SCLC under the regulation of miR-495

Studies have shown that TSPAN12 serves as an oncogenic gene or tumor suppressor depending on the types of cancer. However, its role in the drug resistance of small cell lung cancer (SCLC) is still unknown. In this study, we investigated whether TSPAN12 regulates chemoresistance, proliferation and tumor growth of SCLC under the regulation of miR-495 using two drug resistant cell lines. The results showed that down-regulation of TSPAN12 inhibited cells chemoresistance, proliferation and tumor growth. Besides, TSPAN12 elevation in SCLC specimens correlated with poor pathologic stage and shorter survival time. In addition, the dual luciferase assay indicated that TSPAN12 was one of the directly targeted genes of miR-495. Our study revealed that TSPAN12 promoted chemoresistance of SCLC under the regulation of miR-495. TSPAN12 depletion is a promising strategy for inhibiting the chemoresistance in SCLC.

Inhibition of N-acetylglucosaminyltransferase V enhances the cetuximab-induced radiosensitivity of nasopharyngeal carcinoma cells likely through EGFR N-glycan alterations

N-acetylglucosaminyltransferase V (GnT-V), an enzyme that catalyses the formation of the N-linked β-1-6 branching of oligosaccharides, is related to the radiosensitivity of nasopharyngeal carcinoma (NPC). Cetuximab (C225) is an epidermal growth factor receptor (EGFR) inhibitor used as a radiosensitizer in the treatment of NPC. In this study, we used GnT-V as a molecular target to further sensitize cetuximab-treated NPC cells to radiation. The results from two NPC cell lines (CNE1 and CNE2) revealed that the silencing of GnT-V enhanced cetuximab-induced radiosensitivity by decreasing the β-1-6 branching of oligosaccharides on the EGFR. GnT-V down-regulation combined with cetuximab decreased the survival fraction, healing rate and cell viability and increased the apoptosis rate. Concomitantly, the combination of cetuximab and irradiation did not change the EGFR mRNA and protein levels and decreased the β-1-6 branching on the EGFR. Subsequently, we further explored the signalling downstream of EGF, particularly the PI3K/Akt signalling pathway, and discovered that treatment consisting of GnT-V down-regulation, irradiation and cetuximab was negatively correlated with phospho-Akt and phspho-PI3K. Finally, an in vivo experiment with radiotherapy revealed that the combination of GnT-V down-regulation and cetuximab decelerated tumour growth. In summary, our study demonstrated that the combination of decreased GnT-V activity and cetuximab enhanced NPC radiosensitivity, and the possible mechanism underlying this effect might involve the N-linked β1-6 branching of the EGFR.

KH-type splicing regulatory protein (KHSRP) contributes to tumorigenesis by promoting miR-26a maturation in small cell lung cancer

KH-type splicing regulatory protein (KHSRP) is a multifunctional RNA-binding protein that has a role in tumorigenesis of small cell lung cancer. The KHSRP protein level was shown to be significantly increased in small cell lung cancer (SCLC) tumor tissues compared with normal lung tissues by immunohistochemical staining. Moreover, KHSRP protein levels were strongly associated with T stage in patients with SCLC. Using in vitro assays, we found that knockdown of the KHSRP gene inhibited cell proliferation and increased cell apoptosis but had no effect on cell migration and invasion. We also showed that down-regulation of the KHSRP gene suppressed tumor growth in vivo. Further analyses indicated that KHSRP was involved in miR-26a maturation and inhibited the expression of PTEN in SCLC cells. Taken together, these findings suggested that KHSRP plays an important role in SCLC tumorigenesis and could be a potential novel therapeutic target for SCLC treatment.