High Skp2 Expression Research Articles

Discovery of Novel 1,3-Diphenylpyrazine Derivatives as Potent S-Phase Kinase-Associated Protein 2 (Skp2) Inhibitors for the Treatment of Cancer.

F-box protein S-phase kinase-associated protein 2 (Skp2) is a component of cullin-RING ligases, which is responsible for recruiting and ubiquitinating substrates and subsequently plays its proteolytic and non-proteolytic role. High expression of Skp2 is frequently observed in multiple aggressive tumor tissues and associated with poor prognosis. Several of the Skp2 inhibitors have been reported in the last decades; however, few of them have shown detailed structure-activity relationship (SAR) and potent bioactivity. Herein, based on the hit compound 11a from our in-house library, we optimize and synthesize a series of new 2,3-diphenylpyrazine-based inhibitors targeting the Skp2-Cks1 interaction and further systematically study the SAR. Among them, compound 14i shows potent activity against the Skp2-Cks1 interaction with an IC50 value of 2.8 μM and against PC-3 and MGC-803 cells with IC50 values of 4.8 and 7.0 μM, respectively. Most importantly, compound 14i exhibited effectively anticancer effects on PC-3 and MGC-803 xenograft mice models without obvious toxicity.

Elevated expression of SKP2 correlates with poor prognosis in osteosarcoma: a bioinformatics analysis

Introduction: Osteosarcoma (OS) is the most prevalent kind of bone cancer, but the tumorigenesis and underlying molecular drivers of OS remain unknown. The instability of the cell cycle regulation system, which leads to uncontrolled cell proliferation, is a typical characteristic of carcinogenesis. This study aimed to investigate the expression of SKP2 in human OS and assessed its prognostic value in OS patients. Methods: Three gene expression profile datasets GSE28424, GSE42352 and GSE21257 were obtained from the GEO database. The Wilcoxon rank-sum test was performed to evaluate the differential expression of the SKP2 gene between the OS and the control groups in the GSE28424 and GSE42352 datasets, and the correlation between SKP2 expression and Huvos grade was analysed in the GSE21257 dataset. Subsequently, PPI network, GO and KEGG analyses were constructed. Furthermore, survival analysis between high SKP2 expression group and low SKP2 expression group was performed using the Kaplan–Meier method and log-rank test. In addition, the UALCAN database was used to investigate the association between SKP2 expression and sarcoma. Results: The expression level of SKP2 in OS cells was significantly higher than that in normal bones and mesenchymal stem cell samples. Furthermore, the level of SKP2 expression was observed to decrease as Huvos grade increased. The PPI network was established, and the top ten SKP2-related genes were identified, including CDKs (1, 2, 4, and 6), Cyclin A1-2, E1-2, D1, and CDKN1A. The survival analysis showed that the elevated SKP2 expression level was significantly related to the overall survival of OS patients. Conclusion: Our work adds to our knowledge of SKP2's function in OS and suggests that it might be used as a therapeutic target in the future.

Her2 promotes early dissemination of breast cancer by suppressing the p38 pathway through Skp2-mediated proteasomal degradation of Tpl2.

While mechanisms for metastasis were extensively studied in cancer cells from patients with detectable tumors, pathways underlying metastatic dissemination from early lesions before primary tumors appear are poorly understood. Her2 promotes breast cancer early dissemination by suppressing p38, but how Her2 downregulates p38 is unclear. Here, we demonstrate that in early lesion breast cancer models, Her2 inhibits p38 by inducing Skp2 through Akt-mediated phosphorylation, which promotes ubiquitination and proteasomal degradation of Tpl2, a p38 MAP3K. The early disseminating cells are Her2+Skp2highTpl2lowp-p38lowE-cadherinlow in the MMTV-Her2 breast cancer model. In human breast carcinoma, high Skp2 and low Tpl2 expression are associated with the Her2+ status; Tpl2 expression positively correlates with that of activated p38; Skp2 expression negatively correlates with that of Tpl2 and activated p38. Moreover, the Her2-Akt-Skp2-Tpl2-p38 axis plays a key role in the disseminating phenotypes in early lesion breast cancer cells; inhibition of Tpl2 enhances early dissemination in vivo. These findings identify the Her2-Akt-Skp2-Tpl2-p38 cascade as a novel mechanism mediating breast cancer early dissemination and a potential target for novel therapies targeting early metastatic dissemination.

High Skp2 expression is associated with a mesenchymal phenotype and increased tumorigenic potential of prostate cancer cells

Skp2 is a crucial component of SCFSkp2 E3 ubiquitin ligase and is often overexpressed in various types of cancer, including prostate cancer (PCa). The epithelial-to-mesenchymal transition (EMT) is involved in PCa progression. The acquisition of a mesenchymal phenotype that results in a cancer stem cell (CSC) phenotype in PCa was described. Therefore, we aimed to investigate the expression and localization of Skp2 in clinical samples from patients with PCa, the association of Skp2 with EMT status, and the role of Skp2 in prostate CSC. We found that nuclear expression of Skp2 was increased in patients with PCa compared to those with benign hyperplasia, and correlated with high Gleason score in PCa patients. Increased Skp2 expression was observed in PCa cell lines with mesenchymal and CSC-like phenotype compared to their epithelial counterparts. Conversely, the CSC-like phenotype was diminished in cells in which SKP2 expression was silenced. Furthermore, we observed that Skp2 downregulation led to the decrease in subpopulation of CD44+CD24− cancer stem-like cells. Finally, we showed that high expression levels of both CD24 and CD44 were associated with favorable recurrence-free survival for PCa patients. This study uncovered the Skp2-mediated CSC-like phenotype with oncogenic functions in PCa.

Skp2 expression has different clinicopathological and prognostic implications in lung adenocarcinoma and squamous cell carcinoma.

High expression of S-phase kinase associated protein 2 (Skp2) is associated with numerous clinicopathological parameters, including histology, lymph node metastasis, smoking status, differentiation and Tumor-Node-Metastasis stage in non-small cell lung cancer (NSCLC). Skp2 protein is overexpressed in lung squamous cell carcinoma (LUSC), compared with lung adenocarcinoma (LUAD), whilst the clinicopathological and prognostic implications in LUAD or LUSC remain unclear. A larger study is required to assess the differences in Skp2 expression between these NSCLC types. In the present study, the clinicopathological features and immunohistochemical expression of the Skp2 protein were studied in 500 patients with NSCLC (351 with LUAD and 149 with LUSC). Survival analyses were performed using Kaplan-Meier method and Cox regression model. Skp2 associated genes were identified based on the data from The Cancer Genome Atlas database. Skp2 was overexpressed in patients with LUSC, compared with LUAD (P<0.001). In histology subgroup analysis, differences in Skp2 protein expression were observed in patients with LUAD, based on sex, differentiation, smoking history, stage, lymph node metastasis and tumor diameter (P<0.05), but not in patients with LUSC except for smoking status. High Skp2 protein expression in patients with LUAD was associated with reduced overall survival (OS; P<0.001), but not in patients with LUSC (P=0.686). The multivariate analysis demonstrated that Skp2 expression is an independent unfavorable prognostic factor for OS in patients with LUAD (RR=1.845, P<0.05). Bioinformatics analyses revealed that minichromosome maintenance complex component 2, cell division cycle 45, replication factor C subunit 4, which are differently expressed in LUAD and LUSC, are associated with Skp2 expression and participate in DNA replication and G1/S transition. Skp2 protein expression differs in LUAD and LUSC. The clinicopathological and prognostic implications based on Skp2 expression in LUAD and LUSC should be considered different. LUSC with high Skp2 expression may have robust proliferation ability.

Skp2 Regulates the Expression of MMP-2 and MMP-9, and Enhances the Invasion Potential of Oral Squamous Cell Carcinoma.

Oral squamous cell carcinoma (OSCC) is the most common malignant tumor of the head and neck regions and accounts for more than 90% of cancers in the oral cavity. S-phase kinase-associated protein-2 (Skp2) is a member of the F-box protein family and the substrate recognition subunit of the Skp1-Cullin-F box protein E3 ubiquitin ligase complex. Skp2 is oncogenic and overexpressed in human cancers. The aims of the present study were to determine the clinicopathological significance of Skp2 in OSCC and clarify its function in OSCC cell lines in vitro. Multiple methods including immunohistochemical staining, RT-PCR, western blotting, migration and invasion assays, and siRNA transfection were employed in order to investigate the clinicopathological significance and molecular function of Skp2 in OSCC. The overexpression of Skp2 was more frequent in OSCC than in the normal oral epithelium. It was also more frequently detected in cancers with higher grades according to the T classification, N classification, and pattern of invasion. The high-Skp2 expression group had a significantly poorer prognosis, at 30.1%, than that of the low-expression group, at 63.0%. The downregulation of Skp2 decreased migration and invasion potentials in HSC3 cells. Moreover, the suppression of Skp2 reduced the enzyme activities of MMP-2 and MMP-9 via Sp1. Skp2 may be a prognostic factor in OSCC patients, and may also play crucial roles in the migration and invasion potentials of OSCC cells.

MicroRNA-Related DNA Repair/Cell-Cycle Genes Independently Associated With Relapse After Radiation Therapy for Early Breast Cancer.

Local recurrence and distant failure after adjuvant radiation therapy for breast cancer remain significant clinical problems, incompletely predicted by conventional clinicopathologic markers. We had previously identified microRNA-139-5p and microRNA-1274a as key regulators of breast cancer radiation response in vitro. The purpose of this study was to investigate standard clinicopathologic markers of local recurrence in a contemporary series and to establish whether putative target genes of microRNAs involved in DNA repair and cell cycle control could better predict radiation therapy response in vivo. With institutional ethics board approval, local recurrence was measured in a contemporary, prospectively collected series of 458 patients treated with radiation therapy after breast-conserving surgery. Additionally, independent publicly available mRNA/microRNA microarray expression datasets totaling >1000 early-stage breast cancer patients, treated with adjuvant radiation therapy, with >10 years of follow-up, were analyzed. The expression of putative microRNA target biomarkers--TOP2A, POLQ, RAD54L, SKP2, PLK2, and RAG1--were correlated with standard clinicopathologic variables using 2-sided nonparametric tests, and to local/distant relapse and survival using Kaplan-Meier and Cox regression analysis. We found a low rate of isolated local recurrence (1.95%) in our modern series, and that few clinicopathologic variables (such as lymphovascular invasion) were significantly predictive. In multiple independent datasets (n>1000), however, high expression of RAD54L, TOP2A, POLQ, and SKP2 significantly correlated with local recurrence, survival, or both in univariate and multivariate analyses (P<.001). Low RAG1 expression significantly correlated with local recurrence (multivariate, P=.008). Additionally, RAD54L, SKP2, and PLK2 may be predictive, being prognostic in radiation therapy-treated patients but not in untreated matched control individuals (n=107; P<.05). Biomarkers of DNA repair and cell cycle control can identify patients at high risk of treatment failure in those receiving radiation therapy for early breast cancer in independent cohorts. These should be further investigated prospectively, especially TOP2A and SKP2, for which targeted therapies are available.

SKP2/P27Kip1 pathway is associated with Advanced Ovarian Cancer in Saudi Patients.

Ovarian cancer is the most common gynecological malignancy and constitutes the fifth leading cause of female cancer death. Some biological parameters have prognostic roles in patients with advanced ovarian cancer and their expression may contribute to tumor progression. The aim of this study was to investigate the potential prognostic value of SKP2, genes P27Kip1, K-ras, c-Myc, COX2 and HER2 genes expression in ovarian cancer. This study was performed on two hundred formalin fixed paraffin embedded ovarian cancer and normal adjacent tissues (NAT). Gene expression levels were assessed using real time PCR and Western blotting. Elevated expression levels of SKP2, K-ras, c-Myc, HER2 and COX2 genes were observed in 61.5% (123/200), 92.5% (185/200), 74% (148/200), 96 % (192/200), 90% (180/200) and 78.5% (157/200) of cancer tissues, respectively. High expression of SKP2 and down-regulation of P27 was associated with advanced stages of cancer. The association between high expression of c-Myc and SKP2 with low expression of P27 suggested that the Skp2-P27 pathway may play an important role in ovarian carcinogenesis. Reduced expression of P27 is associated with advanced stage of cancer and can be used as a biological marker in clinical routine assessment and management of women with advanced ovarian cancer.

Acquisition of epithelial–mesenchymal transition is associated with Skp2 expression in paclitaxel-resistant breast cancer cells

Background:Breast cancer is the most common female malignant disease, and the second leading cause of cancer-related death in the United States. Acquired resistance to chemotherapeutic drugs is a pivotal reason that leads to worse treatment outcome of breast cancer. Therefore, it is urgent to elucidate the mechanism of drug resistance in breast cancer.Methods:To investigate the underlying molecular basis of the acquired resistant cells to paclitaxel in breast cancer, we used multiple methods including real-time RT–PCR, western blotting analysis, migration and invasion assays, wound healing assay, and transfection.Results:We found that epithelial–mesenchymal transition (EMT) is involved in paclitaxel-resistant (PR) breast cancer cells. The resistant cells with EMT features exhibit increased migration and invasion activities. Mechanistically, high expression of Skp2 was found to be associated with EMT in PR cells. Notably, depletion of Skp2 in PR cells led to partial reversal of EMT phenotype.Conclusions:These findings suggest that Skp2 was critically involved in PR-mediated EMT. Skp2 could be a potential therapeutic target for breast cancer.

Prognostic Significance Of S-Phase Kinase-Associated Protein 2 (Skp2) In DLBCL Patients Treated With Upfront Autologous Peripheral Blood Stem Cell Transplantation

We have reported that S-phase kinase-associated protein 2 (Skp2) expression in tumor cells is an unfavorable prognostic factor in diffuse large B cell lymphoma (DLBCL) with CHOP-R. Therapeutic strategies other than CHOP-R should be needed for DLBCL patients exhibiting a high Skp2 expression at the time of diagnosis. High dose chemotherapy followed by autologous peripheral blood stem cell transplantation (APBSCT) is mainly adapted for DLBCL patients in high and high intermediate risk groups in IPI. However, the definite beneficial evidence for APBSCT in DLBCL remains unclear.In the present study, we investigated the clinical significance of Skp2 expression in the patients with DLBCL treated with CHOP-R plus high-dose chemotherapy followed by APBSCT. We retrospectively analyzed the outcomes of 93 patients (age range: 14-65). The patients were newly diagnosed as having DLBCL from 2002 to 2012, and were treated with either CHOP-R plus upfront APBSCT (n=31) or CHOP-R (n=62) in the19 hospitals in Kyushu, Japan. All patients had high and high intermediate risk in IPI. All biopsy specimens were immunohistopathologically reconfirmed by one pathologist with expertise before entering into this study. The median follow-up time was 2.3 y. Survival analyses were performed using the Kaplan-Meier method and the Cox proportional Hazard model with inverse probability of treatment weight (IPTW).In background of the patients, age was younger in transplant group (mean age 52) than in non-transplant group (mean age 59). CR rate was higher in non-transplant (30.7%) than in transplant (12.9%). Sex, stage, PS, LDH extranodal lesion and IPI showed no difference in both group.Overall survival (OS) for 3 years were 77.0% and 59% in transplant group and in non-transplant group (P=0.077), respectively. Progression-free survival (PFS) for 3 years, 65.7% and 53.2% in transplant and non-transplant group (P=0.233), respectively. In Skp2 high expression (positive rate >40%) group (n=37), 3y-OS was 44.9% and 16.4% in transplant (n=13) and non-transplant (n=24) group (P=0.065), respectively. 3y-PFS was 40.3% and 7.5% in transplant and non-transplant (P=0.032), respectively (Fig A). However, in low Skp2 expression group (n=56), OS was 100% and 92.7% (P=0.254), PFS was 83.6% and 82.6% (P=0.945)(Fig B)in transplant (n=18) and non-transplant (n=38) group, respectively. In propensity score analysis using center effect, age, extranodal lesion, IPI and CR rate as logistic regression model, transplant group showed the excellent benefit in OS ( OR= 0.469, 95%CI =0.266-0.825, P=0.009) and PFS (OR=0.456, 95%CI=0.255-0.815, P=0.008) in Skp2 high expression group (n=37).P value for transplant x Skp2 interaction was P=0.643 in OS and P=0.020 in PFS.In conclusion, Skp2 was a good biomarker for indication of ABSCT for high risk DLBCL patients. In low expression of Skp2, patients should not be treated with high dose chemotherapy followed by APBSCT, even though in patients with high risk in IPI. However, ABSCT have some advantage in DLBCL patients with high expression of Skp2. Disclosures:No relevant conflicts of interest to declare.

ERK-Dependent Downregulation of Skp2 Reduces Myc Activity with HGF, Leading to Inhibition of Cell Proliferation through a Decrease in Id1 Expression

Hepatocyte growth factor (HGF) has an inhibitory effect on human HepG2 hepatoma cell proliferation. Previously, it was shown that HGF treatment downregulated Id1 and upregulated p16(INK4a) in an ERK-dependent manner, leading to the inhibition of cellular proliferation. Here, new insight suggests that Skp2, an SCF complex component and potential prognosticator in cancer, is downregulated by injection of HGF into established HepG2 xenograft tumors. The downregulation was evident at both the mRNA and protein level and in an ERK-dependent manner. Critically, high expression of Skp2 restored HGF-inhibited cell proliferation, indicating that the inhibitory effect of HGF required the downregulation of Skp2. However, downregulation was not involved in the HGF-induced upregulation of a CDK inhibitor, p27(Kip1), a known SCF-Skp2 target. Instead, data revealed that Skp2 regulated Myc activity, which has oncogenic potential in the generation of hepatocellular carcinoma. Elevated expression of Skp2 or a mutant that is unable to associate with the SCF complex was capable of activating Myc, suggesting that Skp2 does not act on Myc as a component of the SCF complex, and thus functions as an activator of Myc independent of its role in ubiquitination. Furthermore, Skp2 regulated Id1 expression by regulating Myc activity, and the regulation of Skp2 is involved in the activity of p16 promoter through regulation of Id1 expression. Overall, these mechanistic findings provide the first evidence that ERK-dependent downregulation of Skp2 reduced Myc activity, leading to HGF-induced inhibition of cell proliferation through decreased Id1 expression. This study elucidates the molecular details of HGF-induced inhibition of cellular proliferation in liver cancer cells.

Prognostic impact of Skp2, ER and PGR in male and female patients with soft tissue sarcomas

BackgroundS-phase kinase-associated protein 2 (Skp2) is a member of mammalian F-box proteins. The purpose of this study is to clarify the prognostic significance of expression of Skp2 related to gender, estrogen receptor (ER) and progesterone receptor (PGR) in soft tissue sarcomas (STS). Skp2 has been demonstrated to display an oncogenic function since its overexpression has been observed in many human cancers. Optimized treatment of STS requires better identification of high-risk patients who will benefit from adjuvant therapy. The prognostic significance of Skp2 related to ER and PGR in STS has not been sufficiently investigated.MethodsTissue microarrays from 193 STS patients were constructed from duplicate cores of viable and representative neoplastic tumor areas. Immunohistochemistry was used to evaluate the expression of Skp2, ER and PGR.ResultsIn univariate analyses, high tumor expression of Skp2 correlated (p = 0.050) with reduced disease-specific survival (DSS). In subgroup analyses expression of PGR in males (p = 0.010) and in patients older than 60 years (p = 0.043) were negative prognostic factors for DSS. Expression of ER in females was a positive prognostic factor for DSS (p = 0.041). In co-expression analyses in the whole cohort, low expression of Skp2 in combination with low expression of ER was positive for DSS (p = 0.049). In females high expression of Skp2 in combination with low expression of ER was a negative prognosticator (p = 0.021). In the multivariate analyses, age (p = 0.012), malignancy grade (p < 0.001), wide resection margins (P = 0.010), ER negative / PGR positive co-expression profile (p = 0.002) and ER positive / PGR negative co-expression profile (p = 0.015) were independent negative prognostic factors for DSS. In females expression of Skp2 (p = 0.006) was associated with shorter DSS.ConclusionsWe found diverse prognostic impacts of expression of Skp2, ER, PGR and DSS in male and female patients with STS. In men, but not women, ER positive / PGR negative co-expression profile was an independent negative prognostic factor for DSS. In women, but not men, high expression of Skp2 was associated with reduced DSS.

Prognostic impact of Jab1, p16, p21, p62, Ki67 and Skp2 in soft tissue sarcomas.

PurposeThe purpose of this study is to clarify the prognostic significance of expression of Jab1, p16, p21, p62, Ki67 and Skp2 in soft tissue sarcomas (STS). Optimised treatment of STS requires better identification of high risk patients who will benefit from adjuvant therapy. The prognostic significance of Jab1, p16, p21, p62, Ki67 and Skp2 in STS has not been sufficiently investigated.Experimental DesignTissue microarrays from 193 STS patients were constructed from duplicate cores of viable and representative neoplastic tumor areas. Immunohistochemistry was used to evaluate the expression of Jab1, p16, p21, p62, Ki67 and Skp2.ResultsIn univariate analyses, high tumor expression of Ki67 (P = 0.007) and Skp2 (P = 0.050) correlated with shorter disease-specific survival (DSS). In subgroup analysis, a correlation between Skp2 and DSS was seen in patients with malignancy grade 1 or 2 (P = 0.027), tumor size >5 cm (P = 0.018), no radiotherapy given (P = 0.029) and no chemotherapy given (P = 0.017). No such relationship was apparent for Jab1, p16, p21 and p62; but p62 showed a positive correlation to malignancy grade (P = 0.019). Ki67 was strongly positively correlated to malignancy grade (P = 0.001). In multivariate analyses, Skp2 was an independent negative prognostic factor for DSS in women (P = 0.009) and in patients without administered chemotherapy or radiotherapy (P = 0.026).ConclusionsIncreased expression of Skp2 in patients with soft tissue sarcomas is an independent negative prognostic factor for disease-specific survival in women and in patients not administered chemotherapy or radiotherapy. Besides, further studies are warranted to explore if adjuvant chemotherapy or radiotherapy improve the poor prognosis of STS with high Skp2 expression.

Skp2 expression unfavorably impacts survival in resectable esophageal squamous cell carcinoma.

BackgroundThe correlation of S-phase kinase–associated protein 2 (Skp2) with metastasis and prognosis in esophageal squamous cell carcinoma (ESCC) is controversial. The purpose of this study was to explore whether there was a correlation between the expression of Skp2 evaluated by immunohistochemistry and the clinical outcome of patients with operable ESCC, and to further determine the possible mechanism of the impact of Skp2 on survival.MethodsTissue microarrays that included 157 surgically resected ESCC specimens was successfully generated for immunohistochemical evaluation. The clinical/prognostic significance of Skp2 expression was analyzed. Kaplan-Meier analysis was used to compare the postoperative survival between groups. The prognostic impact of clinicopathologic variables and Skp2 expression was evaluated using a Cox proportional hazards model. A cell proliferation assay and a colony formation assay were performed in ESCC cell lines to determine the function of Skp2 on the progression of ESCC in vitro.ResultsSkp2 expression correlated closely with the T category (p = 0.035) and the pathological tumor-node-metastasis (TNM) stage (p = 0.027). High expression of Skp2 was associated with poor overall survival in resectable ESCC (p = 0.01). The multivariate Cox regression analysis demonstrated that pathological T category, pathological N category, cell differentiation, and negative Skp2 expression were independent factors for better overall survival. In vitro assays of ESCC cell lines demonstrated that Skp2 promoted the proliferative and colony-forming capacity of ESCCs.ConclusionsNegative Skp2 expression in primary resected ESCC is an independent factor for better survival. Skp2 may play a pro-proliferative role in ESCC cells.

The Prognostic Value of Skp2 Expression in Egyptian Diffuse Large B-Cell Lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoma worldwide. Both morphologically and prognostically, it represents a disease of a diverse spectrum. S-phase kinase-associated protein 2 (Skp2) is a member of mammalian F-box proteins, which displays S-phase-promoting function through ubiquitin-mediated proteolysis of the cyclin-dependent kinase inhibitor, p27. The aim of this study is to evaluate the prognostic value of Skp2 in DLBCL (70 cases) by immunohistochemical staining technique, and its correlation with the clinicopathological features and survival. Five (25%) control cases (reactive follicular hyperplasia) showed high Skp2 expression compared with 52.9% of DLBCL using 10% as a cutoff point with a significant difference (P=0.04). Skp2 was seen staining the large cells in proliferating germinal centers of the control group. High Skp2 expression in DLBCL was associated with several progressive parameters, such as advanced stage (P=0.036), involvement of more than one extranodal site (P=0.05), and high proliferation (P=0.0001). It was also significantly associated with the presence (P=0.007) and extent (P=0.002) of necrosis and inversely correlated with p27 expression (P=0.0001). From this study, Skp2 expression in DLBCL identified subset of cases characterized by aggressive features such as advanced stage, increased number of extranodal sites, high proliferation, and shorter survival time. The association of Skp2 with necrosis may be a reflection of its ability in promoting proliferative tumor capacity.

Expression and Clinical Significance of pAkt, Skp2 and P27kip1 Protein in Hepatocellular Carcinoma

Objective To explore the expression and clinical significance of pAkt,Skp2 and P27kip1 in hepatocellular carcinoma(HCC) patients.Methods The expression levels of pAkt,Skp2 and P27kip1 in 78 HCC and 21 normal liver tissues were evaluated by immunohistochemistry.The relationship between these molecules and clinicopathological variables was further analyzed.Results The positive expression rates of pAkt and Skp2 in HCC were 43.6% and 47.4% respectively,and significantly higher than those in normal liver tissue(P0.05).P27kip1 was expressed in 34.6% samples of HCC,and significantly lower than that in normal liver tissue(P0.05).pAkt expression level was correlated with tumor size,invasion(or lymph node metastasis) and TNM stage.Skp2 expression level was correlated with tumor size,cancer-embolus in portal vein and TNM stage.P27kip1 expression level was correlated with tumor size,tumor number and TNM stage.Moreover,There was a positive correlation between Skp2 and pAkt expression level(r=0.356,P=0.001),while an inverse correlation between Skp2 and P27kip1 expression level(r=-0.313,P=0.005).HCC patients with high pAkt and Skp2 expression could survive much longer than those with low pAkt and Skp2 expression(P=0.000,Log-rank test).No significant difference of survival time was observed within different P27kip1 expression groups(P0.05,Log-rank test).A multivariate analysis based on Cox regression model demonstrated that TNM stage,pAkt and Skp2 expression might be independent factors affecting the survival time of HCC patients.Conclusion The expression levels of pAkt,Skp2 and P27kip1 were closely correlated to the malignant biological behavior of HCC.Skp2 and pAkt were potential biomarkers evaluate the prognosis of HCC.

Expression of P27kip1 and Skp2 in basal cell carcinoma and its clinical pathological characters

Objective To investigate the expression of Skp2 and P27kip1 and their relationship with the clinicopathologic characters in basal cell carcinoma(BCC). To explore their expression between with the types of BCC of skin, especially in morpheaform BCC group. Methods Immunohistochemical SP technique was used to examine the expression of Skp2 and P27kip1 in 50 cases of BCC and 30 cases of normal tissues of skin.The expression level was analyzed combined with clinicopathological features of age, sex and types of tumor.Results Skp2 positive products located in cytoplasm or nucleus. P27kip1 positive products located in nucleus.The high expression of Skp2 and the low expression of P27kip1 were observed in BCC, there was statistical significance between the tumor group and the control group (P ＜ 0. 05 ) . The expression of Skp2 and P27kip1 were correlated with clinical types of BCC ( P ＜ 0. 05 ), while which were not correlated with age and sex ( P ＞0.05 ). In BCC tissue, Skp2 expression was negatively correlated with P27kip1 ( - 0.624; P ＜ 0.05), there was no correlated with each other in morpheaform BCC group ( P ＞ 0. 05 ). Conclusion The expression of Skp2 and P27kip1 in BCC are significant differences to normal skin tissues, and they are correlated with each other.They may play an important role in carcinogenesis and the development of BCC, and also make targets to treat it. Compared to nodular and superficial BCC group, the expression of Skp2 are higher in morpheaform BCC group, and the expression of P27kip1 is lower. They may play an important role in the types of the BCC and useful factors to predict the types of the tumor, also determine surgical margin for BCC cases. Key words: Neoplasms, basal cell; S-phase kinase-associated proteins; Cyclin-dependent kinase inhibitor p27

The role of Skp2 in extranodal NK/T-cell lymphoma

Expression 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. The 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. Among 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. High expression of Skp2 is an independent unfavorite adverse prognostic factor of extranodal NK/T cell lymphoma.

Prognostic significance of S-phase kinase-associated protein 2 and p27kip1 in patients with diffuse large B-cell lymphoma: effects of rituximab

BackgroundThe F-box protein S-phase kinase-associated protein 2 (Skp2) positively regulates the G1–S transition by promoting degradation of the cyclin-dependent kinase inhibitor p27kip1 (p27). Recent evidence has indicated an oncogenic role of Skp2 in not only carcinogenesis but also lymphomagenesis. Materials and methodsClinicopathologic features and immunohistochemical expression of Skp2 and p27 were studied retrospectively in 671 patients treated with cyclophosphamide, vincristine, doxorubicin and prednisolone (CHOP) or cyclophosphamide, vincristine, doxorubicin and prednisolone plus rituximab (R-CHOP). The median follow-up periods were 43.2 months in the CHOP group (n=425) and 24.0 months in the R-CHOP group (n=246). ResultsHigh Skp2 or low p27 expression correlated significantly with poor overall survival (OS) and progression-free survival (P<0.001) in both treatment groups. The prognostic value of Skp2 or p27 expression was independent of the parameters included in the International Prognostic Index by multivariate analysis. Patients with high Skp2 expression in combination with low p27 expression showed the worst survival. ConclusionsAddition of rituximab to the CHOP regimen did not provide a beneficial outcome to patients with diffuse large B-cell lymphoma with high Skp2 expression and low p27 expression. Skp2 and p27 may be useful prognostic markers in the rituximab era.

P27 deregulation by Skp2 overexpression induced by the JAK2V617 mutation

Janus kinase 2 ( JAK2) V617F mutation has been regarded as the major cause of myeloproliferative disorders (MPD). However, the mechanisms of abnormal cell growth by JAK2V617F have not been elucidated. In this study, cell cycle regulatory protein expression was analyzed using JAK2V617F-Ba/F3 and mock-Ba/F3. JAK2V617F-Ba/F3, but not mock-Ba/F3, showed IL-3 independent cell growth and constitutive STATs activation. Deregulation of p27 Kip1, the cell cycle regulator at the G1 to S transition, was observed in JAK2V617F-Ba/F3 but not in mock-control. p27 Kip1 deregulation was not due to p27 Kip1 mRNA level but due to high Skp2 expression, a subunit of ubiquitin E3 ligase, through the STAT binding in the Skp2 promoter. Like JAK2V617F overexpression, constitutively active STAT5 or STAT3 induced aberrant p27 Kip1 expression of Ba/F3 cells. Similar findings were observed in BCR/ABL-transfected Ba/F3. Our results elucidate the regulatory mechanism by which JAK2V617F modulates Skp2 gene expression through the STAT transcription factors.