Minichromosome maintenance protein family member 6 mediates hepatocellular carcinoma progression by recruiting UBE3A to induce P53 ubiquitination.

With limited therapeutic options for hepatocellular carcinoma (HCC), it is of great significance to investigate the underlying mechanisms and identifying tumor drivers. MCM6, a member of minichromosome maintenance proteins (MCMs), was significantly elevated in HCC progression and associated with poor prognosis. Knockdown of MCM6 significantly inhibited the proliferation and migration of HCC cells with the increased apoptosis ratio and cell cycle arrest, whereas overexpression of MCM6 induced adverse effects. Mechanistically, MCM6 could decrease the P53 activity by inducing the degradation of P53 protein. In addition, MCM6 enhanced the ubiquitination of P53 by recruiting UBE3A to form a triple complex. Furthermore, overexpression of UBE3A significantly rescued the P53 activation and suppression of malignant behaviors mediated by MCM6 inhibition. In conclusion, MCM6 facilitated aggressive phenotypes of HCC cells by UBE3A/P53 signaling, providing potential biomarkers and targets for HCC.

Upregulation of long non-coding RNA MYU promotes proliferation, migration and invasion of esophageal squamous cell carcinoma cells.

Esophageal squamous cell carcinoma (ESCC) is a common malignant tumour type of the digestive system. Long non-coding RNA (lncRNA) c-Myc upregulated (MYU), also known as VPS9 domain-containing 1 antisense 1, was recently discovered. However, the expression of lncRNA MYU in ESCC and its role in tumour progression have remained elusive. In the present study, the expression of lncRNA MYU, Ki-67 and the epithelial-mesenchymal transition-related proteins E-cadherin and Vimentin in ESCC tissues was detected by reverse transcription-quantitative PCR. The expression of Ki-67, E-cadherin and Vimentin in ESCC tissues was also detected by immunohistochemistry. A small interfering RNA plasmid was employed to establish a TE-2 cell line with knockdown on lncRNA MYU. The results indicated that the expression of lncRNA MYU was higher in ESCC tissues than in normal adjacent tissues and that upregulation of lncRNA MYU was a potential biomarker for poor prognosis. The results also suggested that the expression levels of lncRNA MYU were correlated with the histological grade, lymph node metastasis and TNM stage (P<0.05). Silencing of lncRNA MYU expression inhibited the proliferation, migration and invasion, while the expression of lncRNA MYU increased as cell proliferation increased. In addition, the mRNA expression of Vimentin and Ki-67 was decreased in TE-2 cells after lncRNA MYU was knocked down, while E-cadherin mRNA expression was elevated. In conclusion, the present results indicated that lncRNA MYU may regulate the proliferation, migration and invasion of ESCC cells, and may serve as a prognostic biomarker for ESCC.

HAX-1 overexpression in gastric cancer promotes cell proliferation.

BACKGROUND: HAX-1 is involved in the regulation of cellular processes such as apoptosis, proliferation and migration and is closely related to tumorigenesis and tumor metastasis. However, expression of HAX-1 in gastric cancer and its role in tumor development and progression remain unclear. METHODS: Quantitative polymerase chain reaction was used to detect the expression of HAX-1 mRNA in gastric cancer tissues and adjacent non-tumorous tissues. Expression of HAX-1, caspase-3 and caspase-9 was detected by immunohistochemistry in gastric cancer. Small hairpin RNA (shRNA) plasmid was employed to establish SGC-7901 cell lines that expressed HAX-1 at low levels. The effect of HAX-1 expression on cell proliferation will be studied at the cell level. RESULTS: Quantitative polymerase chain reaction (qPCR) showed HAX-1 mRNA expression to be significantly upregulated in gastric cancer tissues. Based on immunohistochemical analysis, upregulation of HAX-1 protein expression correlates positively with the degree of tumor differentiation, vascular tumor thrombus, tumor-node-metastasis stage and lymph node metastatic status and negatively with expression of the apoptosis-related proteins caspase-3 and caspase-9. In addition, high HAX-1 protein expression indicates a poor prognosis. Serum starvation-release experiments revealed that HAX-1 promotes the proliferation of SGC-7901 gastric cancer cells; as cell proliferation increased, expression of HAX-1 also increased, whereas the expression levels of the apoptosis-related proteins caspase-3 and caspase-9 decreased. HAX-1 siRNA transfection experiments demonstrated that HAX-1 gene knockdown causes cell cycle arrest at the G0/G1 phase, inhibits proliferation, and downregulates HAX-1 expression while enhancing expression of apoptosis-related proteins. CONCLUSIONS: HAX-1 might exert its proliferation-promoting and anti-apoptotic effects by inhibiting expression of the apoptosis-related proteins caspase-3 and caspase-9.HAX-1 may be a potential target for the treatment of gastric cancer.

Knockdown of KIF26B inhibits breast cancer cell proliferation, migration, and invasion.

BACKGROUND: Kinesin family member 26B (KIF26B) plays a key role in the development and progression of many human cancers. However, the role and underlying mechanisms of KIF26B in breast cancer cells remain unknown. MATERIALS AND METHODS: In this study, we inhibited the expression of KIF26B in MDA-MB-231 and MCF-7 cells using lentivirus-delivered shRNA. RESULTS: Lentivirus-mediated KIF26B knockdown significantly suppressed cell proliferation, colony formation, migration, and invasion. Furthermore, cell cycle analyses revealed that the percentage of cells in the G0/G1 phase was significantly increased in KIF26B knockdown cells. Moreover, the knockdown of KIF26B significantly promoted cell apoptosis via the upregulation of cleaved caspase-3 and Bax. CONCLUSION: Our data indicate that KIF26B plays a pivotal role in tumor growth and metastasis in breast cancer cells and may be a potential therapeutic target for treating breast cancer.

DISC1 overexpression promotes non-small cell lung cancer cell proliferation.

Neuropsychiatric disorder-associated disrupted-in-schizophrenia-1 (DISC1) activates Wnt/ß-catenin signaling by inhibiting glycogen synthase kinase 3 beta (GSK3ß) phosphorylation, and may promote neural progenitor cell and pancreatic ß-cell proliferation. The present study found that DISC1 promotes non-small cell lung cancer (NSCLC) cell growth. Western blotting and immunohistochemistry analyses showed that DISC1 was highly expressed in NSCLC cell lines and patient tissues. DISC1 expression was negatively associated with phosphorylated (p-) GSK3ß, but positively correlated with a more invasive tumor phenotype and predicted poor NSCLC patient prognosis. siRNA-mediated DISC1 silencing increased p-GSK3ß expression and decreased expression of ß-catenin and Cyclin D1, while DISC1 upregulation produced the opposite results. DISC1 knockdown also reduced NSCLC cell proliferation rates in vitro. These results suggest that DISC1 promotes NSCLC growth, likely through GSK3ß/ß-catenin signaling, and that DISC1 may function as an oncogene and novel anti-NSCLC therapeutic target.

Reduced expression of EphA5 is associated with lymph node metastasis, advanced TNM stage, and poor prognosis in colorectal carcinoma.

Colorectal carcinoma (CRC) is the third most common cancer and a major cause of morbidity and mortality throughout the world. The prognosis of patients has improved markedly over the last 15 years because of the introduction of new therapy including molecular target drugs. To comprehensively understand the molecular process of carcinogenesis of colorectal carcinoma is essential for the diagnosis, prognosis and treatment. EphA5 is a member of the Eph family and plays a critical role in carcinogenesis of lung cancer, prostate cancer, and breast cancer. The expression profile and the role of EphA5 in colorectal carcinoma have not been well investigated till now. In this study, a set of colorectal carcinoma specimens was subjected to immunohistochemical assay using an EphA5 specific antibody. The relationship between the expression of EphA5 and clinicopathological parameters was statistically analyzed. EphA5 was positively expressed in all tested normal mucosa specimens (120/120, 100%) and partly in colorectal carcinoma specimens (70/120, 58.3%). The loss of EphA5 protein was associated with depth of wall invasion (P=0.002), poor tumor differentiation (P<0.001), lymph node metastasis (P<0.001), and advanced TNM stage (P<0.001). The survival analysis showed that patients with reduced expression of EphA5 had a poor overall survival (P=0.017). Our data indicate that EphA5 receptor may be a tumor suppressor in colorectal carcinoma and it may be a new therapeutic target for colorectal carcinoma.

HES5 promotes cellular proliferation of non-small cell lung cancer through STAT3 signaling.

HES5 is a transcription factor activated downstream of the Notch pathway and regulates cell differentiation in multiple tissues. Disruption of its normal expression has been associated with developmental diseases and cancer. But its role in non-small cell lung cancer (NSCLC) remains elusive. Western blot analysis and immunohistochemistry assays demonstrated that HES5 expression was frequently increased in NSCLC tumor tissues and cell lines. Moreover, immunohistochemistry analysis revealed that upregulation of HES5 expression was positively correlated with a more invasive tumor phenotype and poor prognosis. Immunoprecipitation assay indicated that HES5 directly interacted with STAT3. In addition, depletion of HES5 resulted in inhibited phosphorylation of STAT3 and decreased expression of the downstream genes. In vitro studies, using serum starvation-refeeding experiment and HES5-siRNA transfection assay demonstrated that HES5 expression promoted proliferation of NSCLC cells, while HES5 knockdown caused growth arrest of cell cycle at G0/G1 phase, decreased rate of colony formation and alleviated cellular apoptosis. Taken together, out data have delineated that HES5 might contribute to the proliferation of NSCLC by STAT3 signaling.

Overexpression of MYCN promotes proliferation of non-small cell lung cancer.

V-myc avian myelocytomatosis viral oncogene neuroblastoma derived homolog (MYCN) is an oncogene that is known amplified and overexpressed in different human malignancies including small cell lung cancer. However, the role of MYCN in non-small cell lung cancer (NSCLC) development remains elusive. In the present study, Western blot and immunohistochemistry assays demonstrated that MYCN was overexpressed in NSCLC tumor tissues and cell lines. In addition, immunohistochemistry analysis revealed that upregulation of MYCN expression was positively correlated with a more invasive tumor phenotype and poor prognosis. In vitro studies using serum starvation-refeeding experiment and MYCN-siRNA transfection assay demonstrated that MYCN expression promoted proliferation of NSCLC cells, while MYCN knockdown led to decreased cell growth resulted from growth arrest of cell cycle at G0/G1 phase. Furthermore, upregulation and knockdown of sex-determining region Y-box 2 (SRY) (SOX2), which was a well-known oncogene, confirmed that MYCN might be a downstream gene of the transcription factor SOX2. Collectively, our finding suggested that MYCN might contribute to the progression of NSCLC by enhancing cell proliferation, and that targeting MYCN might provide beneficial effects for the clinical therapy of NSCLC.