OBJECTIVETo construct the recombinant plasmids expressing Skp2 short hairpin RNA (shRNA) by pRNAT-U6.1/Neo plasmid vector and observe the effects of RNAi-mediated Skp2 gene silencing on Tca8113 cells.

METHODSFive recombinant eukaryotic expression vectors were successfully constructed using pRNAT-U6.1/Neo plasmid vector separately. After they were transfected into Tca8113 cells with PEI, the interference effects no Skp2 and p27 were detected by RT-PCR and Western blot. The cell cycle of Tca8113 cells were tested by flow cytometry. The proliferation of Tca8113 cells were examined by MTT.

RESULTSIn Skp2shRNA-2 and Skp2shRNA-3 vectors, the expression of Skp2 protein of Tca8113 cells was down-regulated and p27 protein up-regulated (P < 0.01). The cell number during G1/G 0 phases increased 22% (P < 0.01) and during G(2)/M and S phases the number decreased 10% and 12% (P < 0.01). The proliferation of Tca8113 cells slowed down and the cells number decreased (P < 0.01).

CONCLUSIONSSkp2shRNA-2 and Skp2shRNA-3 vectors of shRNA for Skp2 were successfully constructed. They could influence expression of Skp2 and p27 gene. Skp2 may be a promising target of gene therapy on human tongue squamous cell carcinoma.

Carcinoma, Squamous Cell ; genetics ; metabolism ; pathology ; Cell Differentiation ; Cell Line, Tumor ; Cell Proliferation ; Genetic Vectors ; genetics ; Humans ; Plasmids ; genetics ; RNA Interference ; S-Phase Kinase-Associated Proteins ; genetics ; metabolism ; Tongue Neoplasms ; genetics ; metabolism ; pathology ; Transfection

OBJECTIVETo determine the expression of Skp2 in different prostate cancer (PCa) cell lines and tissues, and explore its influence on the androgen receptor (AR) signaling pathway and development of castration-resistant prostate cancer (CRPC).

METHODSThe expression levels of Skp2 and AR in different PCa cell lines were detected by Western blot. After knockdown of Skp2 in the C4-2 and 22RV1 cells transfected with shRNA, the expressions of AR and P27 were determined and the activity of ARR3-Luc measured by dual-luciferase reporter gene assay following treatment with dihydrotestosterone (DHT). The expressions of AR and Skp2 in human naïve PCa or CRPC specimens were detected by immunohistochemical staining followed by analysis of their differences and correlation.

RESULTSThe Skp2 protein expression level was significantly higher in the C4-2 or 22RV1 cells than in the LNCaP cells. DHT treatment increased the expression of Skp2 in the C4-2 cells, but knock-down of Skp2 significantly up-regulated the expression of the well-known downstream protein P27 and down-regulated that of AR. Consistently, DHT treatment increased the activity of ARR3-Luc, while knockdown of Skp2 remarkably decreased it in the C4-2 and 22RV1 cells (P < 0.05). In addition, significantly higher expressions of Skp2 and AR were observed in the CRPC than in the naïve specimens (P < 0.05), with a positive correlation between the two proteins (r = 0.658 1, P < 0.05).

CONCLUSIONSkp2 can enhance the expression and transcription activity of the AR protein in CRPC cells or tissues and is promising to be a critical molecular therapeutic target.

Androgens ; pharmacology ; Cell Line, Tumor ; Dihydrotestosterone ; pharmacology ; Disease Progression ; Gene Knockdown Techniques ; Humans ; Male ; Neoplasm Proteins ; genetics ; metabolism ; Prostatic Neoplasms, Castration-Resistant ; metabolism ; Receptors, Androgen ; genetics ; metabolism ; S-Phase Kinase-Associated Proteins ; physiology ; Transcriptional Activation ; Up-Regulation

OBJECTIVETo investigate the expression of S-phase kinase associated protein 2 (Skp2) in human laryngeal squamous cell carcinomas and to explore the effect of silencing of Skp2 by RNAi on the proliferation and apoptosis and the expressing of p27 protein as well as change of cell cycle in laryngeal carcinoma cell line Hep-2 cell.

METHODSThe expression of Skp2 in laryngeal carcinoma tissues of different differentiation grade was detected by immunohistochemistry. According to the encoding sequence of mRNA of Skp2, two pieces of oligonucleotide sequences were designed and synthesized. The annealed oligonucleotide fragments were subcloned into pGPU6/Neo siRNA expression vector. The recombinant plasmids pGPU6Skp2 were transfected into Hep-2 cells induced by lipofectamine(TM) 2000. The expression level of Skp2 and p27 were examined by flow cytometry. The cell proliferation was examined by MTT assay. Flow cytometry was performed to analyze apoptosis and cell cycle.

RESULTSPositive expression of Skp2 was detected in all 52 cases of laryngeal carcinoma tissues. The positive rate of expression of Skp2 in well-differentiated laryngeal carcinoma group was lower than that in middle-poorly differentiated group (chi(2) = 7.33, P < 0.05). DNA sequencing showed that the oligonucleotide fragments were correctly inserted into pGPU6 vector, and Skp2 protein expression in the transfected cells were inhibited significantly. The fluorescence index of Skp2 protein expression in pGPU6-Skp2 group was significantly inhibited compared with that in blank pGPU6 group (t = 19.42, P < 0.01). The inhibition ratio of cell proliferation in pGPU6-Skp2 group was 26.93% which was strikingly higher than that of blank pGPU6 group 2.47% (t = 15.23, P < 0.01). The apoptosis ratio in pGPU6-Skp2 group was 11.71% which was increased significantly compared with that of their blank pGPU6 group 1.93% (t = 17.92, P < 0.01). In cell cycle study the percentage of S phase cells in pGPU6-Skp2 group was significantly higher than that in blank pGPU6 group (t = 7.73, P < 0.05). The fluorescence index of p27 protein level was significantly higher than that in blank pGPU6 group (t = 2.86, P < 0.05).

CONCLUSIONSThe high level expression of Skp2 in laryngeal carcinoma is significantly related to the differentiation of laryngeal carcinoma. Silencing of Skp2 expression could inhibit cell proliferation and increase cell apoptosis in Hep-2 cells which might be related to the were of p27 protein level and S phase cell cycle arrest of Hep-2 cell.

Apoptosis ; Carcinoma, Squamous Cell ; genetics ; metabolism ; pathology ; Cell Line, Tumor ; Cell Proliferation ; Humans ; Laryngeal Neoplasms ; genetics ; metabolism ; pathology ; RNA, Small Interfering ; genetics ; S-Phase Kinase-Associated Proteins ; metabolism ; Transfection

OBJECTIVE: The current study was designed to examine the expression of Skp2 gene in laryngeal squamous cell carcinoma (LSCC) and to investigate the role of Skp2 gene in tumorigenesis and progression of LSCC. METHOD: FQ-PCR method was used to examined the expression of Skp2 gene in 40 LSCC and 10 normal laryngeal mucosa tissues, and relationship between its expression and clinical biological factors of patients with LSCC was analyzed. RESULT: The median copy number of Skp2 mRNA expression in LSCC was 6622.54 copy/microg RNA, the median copy number of Skp2 mRNA expression in normal laryngeal mucosa tissues was 0 copy/microg RNA, there was a very significant difference between them (P < 0.01); The positive rate of Skp2 mRNA expression in LSCC and adjacent normal laryngeal tissue were 50%, 0, respectively (P < 0.01). The median copy number of Skp2 RNA expression in LSCC with cervical lymph node metastasis was 617138.4 copy/microg RNA, the median copy number of Skp2 mRNA expression in LSCC without cervical lymph node metastasis was 0 copy/microg RNA, there was a very significant difference between them (P < 0.05); The positive rate of Skp2 mRNA expression in LSCC with and without cervical lymph node metastasis were 100.00%, 35.48%, respectively (P < 0.01). CONCLUSION Skp2 gene might have relation with the cervical lymph node metastasis of LSCC. FQ-PCR is an accurate assay to detecting expression of Skp2 mRNA in patient with LSCC. The level of Skp2 mRNA expression might be a new and more accurate marker, and it can be used to predict cervical lymph node metastasis of LSCC.
Adult ; Aged ; Aged, 80 and over ; Carcinoma, Squamous Cell ; genetics ; Female ; Gene Expression ; Humans ; Laryngeal Neoplasms ; genetics ; Lymphatic Metastasis ; Male ; Middle Aged ; Polymerase Chain Reaction ; methods ; RNA, Messenger ; genetics ; S-Phase Kinase-Associated Proteins ; genetics ; metabolism

OBJECTIVE: To investigate the expression of Skp2 and its relation with P27 expression, clinic pathologic features, and prognostic indicator in osteosarcoma. METHODS: We collected osteosarcoma specimen from 52 patients (29 males and 23 females), who were all treated by radical resection of tumor. The expression of Skp2 and P27 was determined by SP immunohistochemistry. Forty-four patients were followed up for 4 to approximately 84(mean = 31.2)months, while the other 8 patients were lost. Twenty of them survived over 5 years and 24 died. RESULTS: In osteosarcoma, Skp2 highly expressed (mean value was 1.74). Expression intensity of Skp2 at the stage III was obviously higher than that of the stage II(IIa and IIb) (P < 0.05). Skp2 expression was correlated with the relapse, metastasis, and 5-year survival in osteosarcoma (P < 0.05), but not with different pathologic types, sex, or age(P > 0.05). The expressions of skp2 and P27 were negative correlation in osteosarcoma (r = -0.907, P < 0.05). CONCLUSION Skp2 plays an important role in the occurrence and development of osteocarcoma by causing the degradation of P27, and can be an important prognostic indicator in osteosarcoma.
Adolescent ; Adult ; Biomarkers, Tumor ; Bone Neoplasms ; metabolism ; pathology ; Female ; Humans ; Male ; Middle Aged ; Neoplasm Invasiveness ; Neoplasm Metastasis ; Osteosarcoma ; metabolism ; pathology ; Prognosis ; Proliferating Cell Nuclear Antigen ; biosynthesis ; genetics ; S-Phase Kinase-Associated Proteins ; biosynthesis ; genetics ; Tumor Cells, Cultured

Although it has been suggested that kinesin family member 14 (KIF14) has oncogenic potential in various cancers, including hepatocellular carcinoma (HCC), the molecular mechanism of this potential remains unknown. We aimed to elucidate the role of KIF14 in hepatocarcinogenesis by knocking down KIF14 in HCC cells that overexpressed KIF14. After KIF14 knockdown, changes in tumor cell growth, cell cycle and cytokinesis were examined. We also examined cell cycle regulatory molecules and upstream Skp1/Cul1/F-box (SCF) complex molecules. Knockdown of KIF14 resulted in suppression of cell proliferation and failure of cytokinesis, whereas KIF14 overexpression increased cell proliferation. In KIF14-silenced cells, the levels of cyclins E1, D1 and B1 were profoundly decreased compared with control cells. Of the cyclin-dependent kinase inhibitors, the p27Kip1 protein level specifically increased after KIF14 knockdown. The increase in p27Kip1 was not due to elevation of its mRNA level, but was due to inhibition of the proteasome-dependent degradation pathway. To explore the pathway upstream of this event, we measured the levels of SCF complex molecules, including Skp1, Skp2, Cul1, Roc1 and Cks1. The levels of Skp2 and its cofactor Cks1 decreased in the KIF14 knockdown cells where p27Kip1 accumulated. Overexpression of Skp2 in the KIF14 knockdown cells attenuated the failure of cytokinesis. On the basis of these results, we postulate that KIF14 knockdown downregulates the expression of Skp2 and Cks1, which target p27Kip1 for degradation by the 26S proteasome, leading to accumulation of p27Kip1. The downregulation of Skp2 and Cks1 also resulted in cytokinesis failure, which may inhibit tumor growth. To the best of our knowledge, this is the first report that has identified the molecular target and oncogenic effect of KIF14 in HCC.
Carcinoma, Hepatocellular/*metabolism ; Cyclin-Dependent Kinase Inhibitor p27/genetics/*metabolism ; Cyclins/genetics/metabolism ; *Cytokinesis ; Gene Silencing ; Hep G2 Cells ; Humans ; Kinesin/genetics/*metabolism ; Liver Neoplasms/*metabolism ; Oncogene Proteins/genetics/*metabolism ; Proteasome Endopeptidase Complex/metabolism ; RNA, Messenger/genetics/metabolism ; S-Phase Kinase-Associated Proteins/genetics/metabolism ; *Ubiquitination

OBJECTIVETo investigate the effects of E2F-1 gene silencing on multidrug resistance of human gastric cancer SGC7901/DDP cells and its possible mechanisms.

METHODSGastric cancer SGC7901/DDP cells were seeded in 6 well plates and divided into three groups: the experimental group, blank control and the negative control groups. For the experimental group, the SGC7901/DDP cells were transfected with recombinant lentivirus vector (Lv-shRNA-E2F-1), while the negative control with an control lentiviral vector (Lv-shRNA-NC) and the blank control with no treatment. The E2F-1 protein level was analyzed by Western blot. MTT assay was used to detect the half maximal inhibitory concentration (IC50) of three chemotherapy drugs including adriamycin, 5-fluorouracil (5-Fu) and cisplatine (DDP) of the three cell groups. Flow cytometry (FCM) was used to detect the pump-out rate of adriamycin and apoptosis rate of the three cell groups. Semi-quantitative RT-PCR and Western blot were also used to detect the protein and mRNA levels of multidrug resistance-associated genes (MDR1, MRP) and apoptosis-related genes (c-Myc, Skp2, cyclinD1).

RESULTSThe expression of E2F-1 protein in the experimental group was significantly lower than that in the negative control and blank control groups (0.794 ± 0.033 vs. 1.487 ± 0.082 vs. 1.511 ± 0.084, P < 0.01). The IC50 of the three chemotherapy drugs (adriamycin, 5-Fu and cisplatine) in the experimental group was significantly lower than that of the negative control and blank control groups, respectively (P < 0.01). Compared with the negative control and blank control groups, the pump-out rate of adriamycin of the experimental group was significantly declined [(0.16 ± 0.01)% vs. (0.37 ± 0.01)% vs. (0.35 ± 0.02)%, P < 0.01]. However, the apoptosis rate of the experimental group was significantly higher than that of the negative control and blank control groups [(33.82 ± 1.26)% vs. (17.34 ± 0.81)% vs. (13.16 ± 1.06)%, P < 0.01]. The results of RT-PCR and Western blot assays showed that mRNA and protein expressions of five genes (MDR1, MRP, CyclinD1, c-Myc, Skp2) in the experimental group were significantly lower than that in the negative control and blank control groups, respectively (P < 0.01).

CONCLUSIONSE2F-1 gene silencing enhances the chemosensitivity of gastric cancer SGC7901/DDP cells to the chemotherapeutic drugs, directly or indirectly downregulated the expression of MDR1 and MRP, and finally reverses the multidrug resistance of the gastric cancer cells. The mechanism may be associated with the suppression of cyclinD1, c-Myc and Skp2.

ATP-Binding Cassette, Sub-Family B, Member 1 ; genetics ; metabolism ; Antibiotics, Antineoplastic ; pharmacology ; Antimetabolites, Antineoplastic ; pharmacology ; Antineoplastic Agents ; pharmacology ; Apoptosis ; Cell Line, Tumor ; Cisplatin ; pharmacology ; Cyclin D1 ; genetics ; metabolism ; Doxorubicin ; pharmacology ; Drug Resistance, Multiple ; Drug Resistance, Neoplasm ; E2F1 Transcription Factor ; genetics ; metabolism ; Fluorouracil ; pharmacology ; Gene Silencing ; Genetic Vectors ; Humans ; Lentivirus ; genetics ; Multidrug Resistance-Associated Proteins ; genetics ; metabolism ; Proto-Oncogene Proteins c-myc ; genetics ; metabolism ; RNA, Messenger ; metabolism ; Recombinant Proteins ; genetics ; metabolism ; S-Phase Kinase-Associated Proteins ; genetics ; metabolism ; Stomach Neoplasms ; metabolism ; pathology ; Transfection

S-phase kinase-associated protein 2 (Skp2), which plays a role in cell cycle regulation, is commonly overexpressed in a variety of human cancers and associated with poor prognosis. However, its role in nasopharyngeal carcinoma (NPC) is not well understood. In this study, we examined the clinical significance of Skp2, with a particular emphasis on overall survival (OS) and disease-free survival (DFS), in NPC cases in South China, where NPC is an epidemic. Additionally, we explored the function of Skp2 in maintaining a cancer stem cell-like phenotype in NPC cell lines. Skp2 expression was assessed for 127 NPC patients using tissue microarrays and immunohistochemistry and analyzed together with clinicopathologic features, OS, and DFS. Skp2 expression was detectable, or positive, in 75.6% of patients. Although there was no correlation between Skp2 and any clinicopathologic factor, Skp2 expression significantly portended inferior OS (P = 0.013) and DFS (P = 0.012). In the multivariate model, Skp2 expression remained significantly predictive of poor OS [P = 0.009, risk ratio (RR) = 4.06] and DFS (P = 0.008, RR = 3.56), and this was also true for clinical stage (P = 0.012 and RR=3.201 for OS; P = 0.002 and RR=1.94 for DFS) and sex (P = 0.016 and RR=0.31 for OS; P = 0.006 and RR = 0.27 for DFS). After Skp2 knockdown, a colony formation assay was used to evaluate the self-renewal property of stem-like cells in the NPC cell lines CNE-1 and CNE-2. The colony formation efficiency in CNE-1 and CNE-2 cells was decreased. In Skp2-transfected CNE-1 and CNE-2 cells, side population (SP) proportion was increased as detected by flow cytometry. Skp2 is an independent prognostic marker for OS and DFS in NPC. Skp2 may play a role in maintaining the cancer stem cell-like phenotype of NPC cell lines.
Adolescent ; Adult ; Aged ; Carcinoma ; Cell Line, Tumor ; China ; Disease-Free Survival ; Female ; Follow-Up Studies ; Gene Knockdown Techniques ; Humans ; Male ; Middle Aged ; Nasopharyngeal Neoplasms ; genetics ; metabolism ; pathology ; Neoplasm Staging ; Neoplastic Stem Cells ; pathology ; RNA, Small Interfering ; genetics ; S-Phase Kinase-Associated Proteins ; genetics ; metabolism ; Sex Factors ; Survival Rate ; Tissue Array Analysis ; Transfection ; Young Adult