Variants in the 3'-untranslated region of CUL3 is associated with risk of esophageal squamous cell carcinoma.

Background: Esophageal squamous cell carcinoma (ESCC) is one of the most lethal cancers in China. Recently, a study identified that cullin 3 (CUL3) was significantly mutated and deleted in ESCC. We then hypothesis that germline variants in CUL3 may also associated with the susceptibility of ESCC. Variants in the gene 3'-untranslated region (3'-UTR) may associate with gene expression by altering miRNAs binding. Material and Methods: We systematically searched for variants in the 3'-UTR of CUL3 using the Ensembl database. Taqman SNP Genotyping Assay was performed in 638 ESCC cases and 546 controls to examine the association between the rs2396092 and the risk of ESCC. The eQTL analysis for CUL3 were conducted by using the GTEx database. Results: We identified that the rs2396092 was significantly associated with the susceptibility of ESCC. Compared with the TT genotype carriers, the CT genotype and CC genotype carriers were correlated with risk of ESCC with odds ratio being 1.33 (95% CI: 1.04-1.70, P=0.0222) and 1.63 (95% CI: 1.07-2.50, P=0.0241), respectively. Different genotypes of rs2396092 was also shown to be correlated with altered CUL3 expression. Conclusion: The results emphasize the importance of CUL3 in the development of ESCC and may contribute to the personalized prevention of this cancer in the future.

Clinical significance of HOTAIR expression in colon cancer.

AIM: To detect the expression of the long noncoding RNA HOTAIR in colon cancer and analyze its relationship with clinicopathological parameters of colon cancer. METHODS: Total RNA was extracted from 80 colon cancer tissues and matched tumor-adjacent normal colon tissues and reverse transcribed. Quantitative polymerase chain reaction was used to detect the expression of HOTAIR. The relationship between the expression of HOTAIR and clinicopathological parameters of colon cancer was analyzed. RESULTS: The expression of HOTAIR was significantly higher in colon cancer tissues than in matched tumor-adjacent normal colon tissues (P < 0.05). HOTAIR expression was significantly higher in cases with lymph node metastasis than in those without metastasis; in lowly differentiated and undifferentiated cases than in highly and moderately differentiated cases; and in stages III + IV cases than in stages I + II cases (P < 0.05). CONCLUSION: HOTAIR expression is upregulated in colon cancer, suggesting that HOTAIR plays an important role in the tumorigenesis, development and metastasis of colon cancer. HOTAIR may act as an oncogene and represents a new molecular target for the treatment of colon cancer.

PTEN regulates angiogenesis and VEGF expression through phosphatase-dependent and -independent mechanisms in HepG2 cells.

Hepatocellular carcinoma (HCC) is a typical hypervascular tumor, and increased levels of vascular endothelial growth factor (VEGF) are associated with progression of HCC. Tumor suppression gene PTEN (phosphatase and tensin homolog deleted on chromosome 10), an important antagonist of the phosphoinositide-3-kinase (PI3K)/adenosine triphosphate-dependent tyrosine kinase (Akt) pathway, is also commonly lost or mutated in HCC. However, the effect of PTEN on VEGF-mediated angiogenesis in HCC remains unknown. To explore this relationship, we expressed a panel of PTEN mutants in human HCC cells with low expression of PTEN (HepG2 cells). Overexpression of PTEN in HepG2 cells resulted in the downregulation of proliferation and migration of cocultured endothelial cells and decreased expression of hypoxia-inducible factor 1 (HIF-1) and VEGF. Similarly, using a nude mouse model, we demonstrated that PTEN decreased expression of HIF-1 and VEGF and suppressed HepG2-induced angiogenesis. This inhibitory effect was not observed in cells expressing a phosphatase-deficient PTEN mutant, suggesting that PTEN inhibits angiogenesis and VEGF through a phosphatase-dependent pathway. Strikingly, reintroducing the C2 domain of PTEN also resulted in a significant decrease in angiogenesis and VEGF expression, although it did not affect Akt phosphorylation or HIF-1 expression. In summary, this study suggests the novel viewpoint that PTEN suppresses angiogenesis and VEGF expression in HCC through both phosphatase-dependent and -independent mechanisms.

PTEN inhibits the migration and invasion of HepG2 cells by coordinately decreasing MMP expression via the PI3K/Akt pathway.

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors. Most patients with HCC die within one year after diagnosis largely because of frequent tumor recurrence and metastasis. The tumor suppressor gene PTEN (phosphatase and tensin homolog deleted on chromosome 10) is one of the most commonly lost or mutated genes in a variety of human cancers, including HCC. PTEN antagonizes phosphoinositide-3-kinase (PI3K)/ATP-dependent tyrosine kinase (Akt) signaling, thereby negatively regulating a multitude of biological aggressive tumor behaviors. However, the direct role and mechanism of PTEN in the regulation of invasion and invasion-related gene expression in HCC remain to be elucidated. In this study, we introduced wild-type PTEN or phosphatase-dead PTEN into HepG2 cells that have low expression of PTEN. We found that overexpression of PTEN inhibits HepG2 cell growth via cell cycle arrest without inducing apoptosis. Matrigel invasion and scratch assays indicated that PTEN significantly inhibits HepG2 cell migration and invasion in vitro. On the molecular level, overexpression of PTEN suppressed expression of matrix metalloproteinase (MMP)-2 and -9 in HepG2 cells. Similarly, treatment of HepG2 cells with the PI3K/Akt pharmacological inhibitor, LY294002, potently suppressed cell migration and invasion as well as expression of MMPs. However, the phosphatase-dead PTEN mutant did not exert the same effects. Our data show that PTEN not only inhibits HepG2 cell growth via cell cycle arrest, but also suppresses cell invasion in a PI3K/Akt/MMP-dependent manner, which suggests that loss or mutation of PTEN may contribute to increased cell invasion and facilitates HCC progression.

Delisheng, a Chinese medicinal compound, exerts anti-proliferative and pro-apoptotic effects on HepG2 cells through extrinsic and intrinsic pathways.

The anti-proliferative, cytotoxic and apoptogenic activities of delisheng, a Chinese medicinal compound, has been investigated. In this study, the hepatocarcinoma cell line (HepG2) and the liver cell line (L-02) were exposed to delisheng (6.25, 50 and 100 µl/ml). Delisheng suppressed the proliferation and viability of normal liver L-02 cells slightly, but strongly inhibited the proliferation and viability of hepatocarcinoma HepG2 cells. The flow cytometric analysis of HepG2 cells demonstrated that delisheng primarily arrested the HepG2 cells at the G1 phase of the cell cycle. Annexin V-FITC/PI staining corroborates the apoptogenic nature of delisheng on HepG2 cells. The anti-proliferative and pro-apoptotic effect of delisheng in HepG2 cells was associated with changes in the Bcl-2/Bax ratio and the induction of caspase-mediated apoptosis. Upregulation of DR5 expression was observed in HepG2 cells after treatment with delisheng. The findings from the present study suggest that delisheng has selective cytotoxic activities against HepG2 cells. Delisheng triggered time- and dose-dependent apoptosis in HepG2 cells by activating the mitochondria-mediated and death receptor-mediated apoptotic pathways.

Agents from amphibians with anticancer properties.

Amphibians have been found to be a source of agents with anticancer properties. Bufalin, for example, is an anticancer agent that may induce apoptosis by its interaction with other genes and cellular components. Certain peptides with anticancer activities have been found in amphibian skin; they include magainins, aureins, citropin 1.1 and gaegurins. These peptides may exert a cytotoxic effect on human cancer cells through various mechanisms. Onconase, amphinase, cSBL (sialic acid-binding lectin purified from Rana catesbeiana eggs) and jSBL (sialic acid-binding lectin purified from Rana japonica eggs), which belong to the RNase A family, were purified from the oocyte cells and eggs of three amphibians, and they induce cytotoxicity by degrading cellular RNA. This paper discusses the medical and pharmaceutical significance of products derived from amphibians.

WITHDRAWN: Treatment of combining antiangiogenic therapy and cytotoxic chemotherapy reduce the cancer stem-like cell fraction in hepatocarcinoma xenografts.

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[Small interfering RNA suppression of transducer and activator of transcription 3 (STAT3) signaling pathway: inhibitory effect on proliferation of human esophageal squamous carcinoma cells].

OBJECTIVE: To investigate the efficiency of blockage of constitutively activated STAT3 signaling by small interfering RNA (siRNA), and to explore the inhibitory effects on the proliferation of human esophageal squamous carcinoma cells (EC9706 and Eca109). METHODS: EC9706 and Eca109 were transfected with chemical synthesized STAT3 siRNA (100 nmol/L). RT-PCR and Western blot were used to detect STAT3 mRNA and protein expression, including phosphorylated-STAT3 (p-STAT3) before and after the transfection respectively. The changes of DNA-binding activity and cell proliferation were evaluated by electrophoretic mobility gel shift assay and MTT, respectively. Stages of cell cycle were determined by flow cytometry. RESULTS: Expression levels of STAT3 mRNA and STAT3, p-STAT3 proteins were progressively inhibited by STAT3 siRNA at various time points after transfection. STAT3-DNA-binding activity was suppressed after transfection evidenced by electrophoretic mobility gel shift assay. The cell cycle was arrested at G(0)/G(1) phase along with a significant inhibition of cell proliferation after STAT3 siRNA treatment. CONCLUSION: STAT3 siRNA specifically and efficiently blocks the constitutively activated STAT3 signaling pathway in human esophageal squamous carcinoma cells, resulting in cell cycle arrest and proliferation inhibition.

[Constitutive activation of signal transducers and activators of transcription 3 and expression of its target gene products in human ESCC cell line].

OBJECTIVE: To investigate the expression of signal transducers and activators of transcription 3 (STAT3) and its target gene products including vascular endothelial growth factor (VEGF) and Bcl-2 in two human esophageal squamous cell carcinoma (ESCC) cell lines for understanding whether STAT3 signaling transduction pathway was constitutively activated in ESCC cell lines. METHODS: Western blotting was used to determine the protein levels of STAT3, p-STAT3 (activated STAT3), VEGF and Bcl-2 in two ESCC cell lines (EC9706 and Eca109). Nuclear proteins from the ESCC cell lines were extracted to evaluate the DNA-binding activity by electrophoretic mobility gel shift assay (EMSA). RT-PCR was used to detect the mRNA of STAT3, VEGF and Bcl-2. RESULTS: Western blotting and RT-PCR revealed that STAT3, VEGF and Bcl-2 protein and mRNA were overexpressed in the two ESCC cell lines, which contained constitutively activated STAT3 signaling transduction pathway. The results of EMSA of the nuclear protein showed high DNA-binding activity of STAT3. CONCLUSION: STAT3 signaling transduction pathway is constitutively activated in human ESCC cell lines, suggesting that STAT3 may play a critical role in the carcinogenesis of the esophagus.