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

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

Adult ; Aged ; Aged, 80 and over ; Breast Neoplasms ; metabolism ; pathology ; Carcinoma ; metabolism ; pathology ; Cyclin-Dependent Kinase Inhibitor p27 ; metabolism ; Female ; Humans ; Lymphatic Metastasis ; Middle Aged ; Neoplasm Staging ; Phosphorylation ; Prognosis ; S-Phase Kinase-Associated Proteins ; metabolism ; Threonine ; metabolism

S-phase kinase-associated protein 2 (Skp2) belongs to the F-box protein family. It is a component of the SCF E3 ubiquitin ligase complex. Skp2 has been shown to regulate cellular proliferation by targeting several cell cycle-regulated proteins for ubiquitination and degradation, including cyclin-dependent kinase inhibitor p27. Skp2 has also been demonstrated to display an oncogenic function since its overexpression has been observed in many human cancers. This review discusses the recent discoveries on the novel roles of Skp2 in regulating cellular senescence, cancer progression, and metastasis, as well as the therapeutic potential of targeting Skp2 for human cancer treatment.
Animals ; Cell Movement ; Cellular Senescence ; Cyclopentanes ; pharmacology ; Disease Progression ; Drug Delivery Systems ; methods ; Gene Expression Regulation, Neoplastic ; Humans ; Neoplasms ; metabolism ; pathology ; therapy ; Pyrimidines ; pharmacology ; S-Phase Kinase-Associated Proteins ; antagonists & inhibitors ; metabolism ; physiology ; Ubiquitination

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

Antineoplastic Agents ; pharmacology ; Apoptosis ; drug effects ; Carcinoma, Hepatocellular ; metabolism ; pathology ; Cell Cycle ; drug effects ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Cyclin-Dependent Kinase Inhibitor p27 ; metabolism ; Dose-Response Relationship, Drug ; Gene Expression Regulation, Neoplastic ; drug effects ; Humans ; Liver Neoplasms ; metabolism ; pathology ; PTEN Phosphohydrolase ; metabolism ; S-Phase Kinase-Associated Proteins ; metabolism ; Thiazolidinediones ; pharmacology

BACKGROUND AND OBJECTIVEExpression of Skp2 was related with the prognosis of several tumors. However, there was no intensive study on the relationship between Skp2 and extranodal NK/T cell lymphoma. This study was to explore the role of Skp2 in extranodal NK/T cell lymphoma.

METHODSThe clinicopathological data of 39 patients with extranodal NK/T cell lymphoma were analyzed. The expression of Skp2 was examined by immunohistochemistry on formalin fixed, paraffin embedded tissue sections.

RESULTSAmong the patients with high expression of Skp2, complete remission (CR) rate was only 14.3% (2/14). However, CR rate among the patients with low expression of Skp2 was 68.0% (17/25). Significant difference was shown between these two groups (P < 0.001). In the group of low expression, the median overall survival (OS) was 85.59 months (95% CI: 35.83 135.34 months), the 1 and 2 year OS rates were 81% and 71%, respectively. However, in the group of high expression, the median OS was only 9.73 months (95% CI: 2.05-17.40 months), the 1 and 2 year OS rates were 42% and 14%, respectively. There was statistical difference between these two groups (P < 0.001). Multivariate analysis showed that Skp2 expression (P <0.001), LDH (P = 0.026) and ECOG PS (P = 0.003) were dependent prognostic factors of extranodal NK/T cell lymphoma.

CONCLUSIONHigh expression of Skp2 is an independent unfavorite adverse prognostic factor of extranodal NK/T cell lymphoma.

Adolescent ; Adult ; Aged ; Antineoplastic Combined Chemotherapy Protocols ; therapeutic use ; Female ; Follow-Up Studies ; Humans ; L-Lactate Dehydrogenase ; blood ; Lymphoma, Extranodal NK-T-Cell ; drug therapy ; metabolism ; pathology ; radiotherapy ; Male ; Middle Aged ; Neoplasm Staging ; Remission Induction ; S-Phase Kinase-Associated Proteins ; metabolism ; Survival Rate ; Young Adult

BACKGROUND/AIMS: Ligands for peroxisome proliferator-activated receptor gamma (PPAR gamma), a member of the ligand-activated nuclear receptor superfamily, exhibit anti-tumoral effects and are associated with de novo synthesis of proteins involved in regulating the cell cycle and cell survival/death. Helicobacter pylori (H. pylori) is an etiologic agent for gastric adenocarcinoma, and raises the cell turnover of gastric epithelium. The aim of this study was to investigate the effect of PPAR gamma ligand rosiglitazone on the cell proliferation and the expressions of p27 and Skp2 protein in H. pylori infected gastric epithelial cells. METHODS: We examined the expression of PPAR gamma by Western blot in H. pylori infected AGS human gastric epithelial cells. The effect of rosiglitazone on the survival of H. pylori infected AGS cells was assessed by cell viability assay. After the treatment of rosiglitazone in H. pylori infected AGS cells, the expressions of p27 and Skp2 were assessed by Western blot. RESULTS: The expression of PPAR gamma protein was increased in H. pylori infected AGS cells. Cell growth was inhibited and decreased in dose- and time- dependent manner in H. pylori infected AGS cells treated with rosiglitazone. A decrease in Skp2 expression and a reciprocal increase in p27 expression were found in dose- and time-dependent manner in H. pylori infected AGS cells treated with rosiglitazone. CONCLUSIONS: Rosiglitazone inhibited the growth of H. pylori infected AGS cells. Rosiglitazone attenuated Skp2 expression, thereby promoting p27 accumulation in H. pylori infected human gastric epithelial cells. Further studies will be needed to find the effects of accumulation on cell turnover in H. pylori infection and the role in the H. pylori-associated gastric carcinogenesis.
Anti-Bacterial Agents/*pharmacology ; Cell Line ; Cell Proliferation ; Cyclin-Dependent Kinase Inhibitor p27/*metabolism ; Epithelial Cells/metabolism/*microbiology ; Gastric Mucosa/cytology/metabolism/*microbiology ; *Helicobacter pylori ; Humans ; PPAR gamma/antagonists &inhibitors/metabolism ; S-Phase Kinase-Associated Proteins/*metabolism ; Thiazolidinediones/*pharmacology

OBJECTIVE: To study the expression of SKP2 and MRP-1/CD9 protein in glottic cancer and adjacent tissues, and to analyze its significance for a safe surgical margin. METHOD: Thirty-eight cases of glottic squamous cell carcinoma were studied for its cancer tissue, tissue 2 mm, 5 mm, and 10 mm away from cancer, and 10 cases of vocal cord polyp were served as control. SKP2 and MRP-1/CD9 protein were examined by immunohistochemical method. RESULT: The positive expression of SKP2 proteins decreased in sequence of polyp mucosa, those adjacent to carcinoma (10 mm, 5 mm, 2 mm ) and cancer tissue, and there was significant difference between them (P < 0.05); On the contrary, the positive expression of the MRP-1/CD9 proteins increased in sequence of polypous mucosa, those adjacent to carcinoma (10 mm, 5 mm, 2 mm) and cancer tissue,and there was significant difference between them (P < 0.05). CONCLUSION SKP2 and MRP-1/CD may act as the reference index for judging the biological specialty of LSCC. It is appropriate to regard 5 mm or above 5 mm away from tumors as a safe margin for surgical treatment of glottic carcinoma.
Adult ; Aged ; Antigens, CD ; metabolism ; Female ; Glottis ; pathology ; Humans ; Laryngeal Neoplasms ; metabolism ; pathology ; Male ; Membrane Glycoproteins ; metabolism ; Middle Aged ; Neoplasm Staging ; Neoplasms, Squamous Cell ; metabolism ; pathology ; S-Phase Kinase-Associated Proteins ; metabolism ; Tetraspanin 29