Jincheng Pan

The expression and role of protein kinase C (PKC) epsilon in clear cell renal cell carcinoma

Protein kinase C epsilon (PKCε), an oncogene overexpressed in several human cancers, is involved in cell proliferation, migration, invasion, and survival. However, its roles in clear cell renal cell carcinoma (RCC) are unclear. This study aimed to investigate the functions of PKCε in RCC, especially in clear cell RCC, to determine the possibility of using it as a therapeutic target. By immunohistochemistry, we found that the expression of PKCε was up-regulated in RCCs and was associated with tumor Fuhrman grade and T stage in clear cell RCCs. Clone formation, wound healing, and Borden assays showed that down-regulating PKCε by RNA interference resulted in inhibition of the growth, migration, and invasion of clear cell RCC cell line 769P and, more importantly, sensitized cells to chemotherapeutic drugs as indicated by enhanced activity of caspase-3 in PKCε siRNA-transfected cells. These results indicate that the overexpression of PKCε is associated with an aggressive phenotype of clear cell RCC and may be a potential therapeutic target for this disease.

Association between RASSF1A Promoter Methylation and Prostate Cancer: A Systematic Review and Meta-Analysis

Prostate cancer (PCa) remains as one of the most common cause of cancer related death among men in the US. The widely used prostate specific antigen (PSA) screening is limited by low specificity. The diagnostic value of other biomarkers such as RAS association domain family protein 1 A (RASSF1A) promoter methylation in prostate cancer and the relationship between RASSF1A methylation and pathological features or tumor stage remains to be established. Therefore, a meta-analysis of published studies was performed to understand the association between RASSF1A methylation and prostate cancer. In total, 16 studies involving 1431 cases and 565 controls were pooled with a random effect model in this investigation. The odds ratio (OR) of RASSF1A methylation in PCa case, compared to controls, was 14.73 with 95% CI = 7.58–28.61. Stratified analyses consistently showed a similar risk across different sample types and, methylation detection methods. In addition, RASSF1A methylation was associated with high Gleason score OR=2.35, 95% CI: 1.56–3.53. Furthermore, the pooled specificity for all included studies was 0.87 (95% CI: 0.72–0.94), and the pooled sensitivity was 0.76 (95% CI: 0.55–0.89). The specificity in each subgroup stratified by sample type remained above 0.84 and the sensitivity also remained above 0.60. These results suggested that RASSF1A promoter methylation would be a potential biomarker in PCa diagnosis and therapy.

Vasculogenic Mimicry in Prostate Cancer: The Roles of EphA2 and PI3K.

BACKGROUND. Aggressive tumor cells can form perfusable networks that mimic normal vasculature and enhance tumor growth and metastasis. A number of molecular players have been implicated in such vasculogenic mimicry, among them the receptor tyrosine kinase EphA2, which is aberrantly expressed in aggressive tumors. Here we study the role and regulation of EphA2 in vasculogenic mimicry in prostate cancer where this phenomenon is still poorly understood. METHODS. Vasculogenic mimicry was characterized by tubules whose cellular lining was negative for the endothelial cell marker CD34 but positive for periodic acid-Schiff staining, and/or contained red blood cells. Vasculogenic mimicry was assessed in 92 clinical samples of prostate cancer and analyzed in more detail in three prostate cancer cell lines kept in three-dimensional culture. Tissue samples and cell lines were also assessed for total and phosphorylated levels of EphA2 and its potential regulator, Phosphoinositide 3-Kinase (PI3K). In addition, the role of EphA2 in vasculogenic mimicry and in cell migration and invasion were investigated by manipulating the levels of EphA2 through specific siRNAs. Furthermore, the role of PI3K in vasculogenic mimicry and in regulating EphA2 was tested by application of an inhibitor, LY294002. RESULTS. Immunohistochemistry of prostate cancers showed a significant correlation between vasculogenic mimicry and high expression levels of EphA2, high Gleason scores, advanced TNM stage, and the presence of lymph node and distant metastases. Likewise, two prostate cancer cell lines (PC3 and DU-145) formed vasculogenic networks on Matrigel and expressed high EphA2 levels, while one line (LNCaP) showed no vasculogenic networks and lower EphA2 levels. Specific silencing of EphA2 in PC3 and DU-145 cells decreased vasculogenic mimicry as well as cell migration and invasion. Furthermore, high expression levels of PI3K and EphA2 phosphorylation at Ser897 significantly correlated with the presence of vasculogenic mimicry and in vitro inhibition of PI3K by LY294002 disrupted vasculogenic mimicry, potentially through a reduction of EphA2 phosphorylation at Ser897. CONCLUSIONS. The expression levels of PI3K and EphA2 are positively correlated with vasculogenic mimicry both in vivo and in vitro. Moreover, phosphorylation levels of EphA2 regulated by PI3K are also significantly associated with vasculogenic mimicry in vivo. Based on its functional implication in vasculogenic mimicry in vitro, EphA2 signaling may be a potential therapeutic target in advanced prostate cancer.

Association of DSC3 mRNA down-regulation in prostate cancer with promoter hypermethylation and poor prognosis.

Background Desmocollin 3 (DSC3), a member of the cadherin gene superfamily, is associated with pathogenesis of some cancers, but its role in prostate cancer (PCa) remains largely unknown. Methods DSC3 gene expression level in available PCa microarray dataset was examined using the Oncomine database. DSC3 transcript expression in prostate cell line panel and an independent tissue cohort (n = 52) was estimated by quantitative PCR (Q-PCR). Epigenetic status of DSC3 gene promoter in PCa was investigated by uploading three dataset (ENCODE Infinium 450K array data and two methylation sequencing) in UCSC genome browser. While pyrosequencing analysis measured promoter DNA methylation, Q-PCR estimates were obtained for DSC3 transcript re-expression after 5-Aza-deoxycytidine (5-Aza) treatment. Clinical relevance of DSC3 expression was studied by Kaplan-Meier survival analysis. Finally, functional studies monitoring cell proliferation, migration and invasion were performed in prostate cell lines after siRNA mediated DSC3 knockdown or following 5-Aza induced re-expression. EMT markers Vimentin and E-cadherin expression was measured by Western Blot. Results Microarray data analyses revealed a significant decrease in DSC3 transcript expression in PCa, compared to benign samples. Q-PCR analysis of an independent cohort revealed DSC3 transcript down-regulation, both in PCa cell lines and tumor tissues but not in their benign counterpart. Examination of available NGS and Infinium data identified a role for epigenetic regulation DSC3 mRNA reduction in PCa. Pyrosequencing confirmed the increased DSC3 promoter methylation in cancer cell lines and restoration of transcript expression upon 5-Aza treatment further corroborated this epigenetic silencing mechanism. Importantly Kaplan-Meier analysis of an outcome cohort showed an association between loss of DSC3 expression and significantly increased risk of biochemical recurrence. Functional studies indicate a role for epithelial–mesenchymal transition in DSC3 regulated cell migration/invasion. Conclusion Taken together, our data suggests that DNA methylation contributes to down-regulation of DSC3 in prostate cancer, and loss of DSC3 predicts poor clinical outcome.

The expression and role of tyrosine kinase ETK/BMX in renal cell carcinoma.

BackgroundExpression of the non-receptor tyrosine kinase ETK/BMX has been reported in several solid tumors, but the underlying molecular mechanisms and its clinical significance in renal cell carcinoma (RCC) remain to be elucidated.MethodsETK expression in 90 human RCC and 30 human normal renal tissue samples was examined by immunohistochemistry and compared with several clinicopathologic parameters. To further demonstrate the biological function of ETK in RCC, Western blot was used to test the expression level of ETK protein in RCC cell lines. Subsequent to the downregulation of ETK by small interfering RNA, the effects of ETK on RCC cell growth, apoptosis, migration and invasion were assessed by methyl thiazol tetrazolium assay, flow cytometry and transwell assay. And the varying expression of VEGF, STAT3 and phosphorylated STAT3 (p-STAT3) in RCC were evaluated by Western blot.ResultsImmunohistochemistry analysis showed that ETK expression was highly increased in RCC and was positively correlated with clinical stage, grade and metastasis. Simultaneously, the overall survival time in patients with higher ETK expression was obviously shorter than that in patients with lower ETK expression. ETK was also detected in RCC cell lines. Moreover, the down-regulating ETK significantly inhibited RCC cell growth, migration, invasion and promoted apoptosis. The expression of VEGF and p-STAT3 were also decreased.ConclusionsOur study suggests that the overexpression of ETK is associated with the malignancy and disease progression of RCC. Since ETK is also involved in RCC cell biological function and VEGF-ETK-STAT3 loop, ETK may be used as a potential therapeutic target for RCC.

Matrix metalloproteinase-9 is required for vasculogenic mimicry by clear cell renal carcinoma cells☆

BACKGROUND Vasculogenic mimicry (VM), a new pattern of tumor microcirculation system, has been proved to be important for tumor growth and progression and may be one of the causes of antiangiogenesis resistance. Matrix metalloproteinase-9 (MMP9) was shown to correlate with VM formation in some other cancers. However, the relationship between VM formation and MMP9 in renal cell carcinoma (RCC) has not been determined. METHODS The VM formation and MMP9 expressions were analyzed by CD34/periodic acid-Schiff dual staining and immunohistochemistry in 119 RCC specimens. We used a well-established 3-dimention culture model to compare VM formation in 786-O, 769-P, and HK-2 cell lines in vitro. MMP9 expressions on either messenger RNA or protein levels were compared among the cell lines by quantitative polymerase chain reaction or Western blot. To determine further the relationship between MMP9 and VM in RCC, 786-O and 769-P were treated with specific MMP9 inhibitor or small interfering RNA. VM formation, cell migration, and invasion were subsequently assessed by 3-dimention culture, wound-healing, and transwell assays. RESULTS Immunohistochemistry demonstrated both VM formation and MMP9 overexpression were positively associated with clinical staging, pathological grade, and metastasis (P<0.01). VM formation was closely correlated with MMP9 overexpression in RCC (r = 0.602, P<0.01). Lower MMP9 expression level was observed in normal kidney cell line HK-2, which was unable to form VM on Matrigel, whereas higher expression of MMP9 was found in VM-forming cancer cell lines 786-O and 769-P. Inhibition of MMP9 not only disrupted VM formation in 786-O and 769-P but also reduced cell migration and invasion. CONCLUSIONS These results indicate an intimate relationship between MMP9 overexpression and VM formation in RCC. Treatments targeting VM formation by inhibiting the activity of MMP9 could be beneficial in RCC therapy.

Downregulation of miR-141-3p promotes bone metastasis via activating NF-κB signaling in prostate cancer

BackgroundClinically, prostate cancer (PCa) exhibits a high avidity to metastasize to bone. miR-141-3p is an extensively studied miRNA in cancers and downregulation of miR-141-3p has been widely reported to be involved in the progression and metastasis of several human cancer types. However, the clinical significance and biological roles of miR-141-3p in bone metastasis of PCa are still unclear.MethodsmiR-141-3p expression was examined in 89 non-bone metastatic and 52 bone metastatic PCa tissues by real-time PCR. Statistical analysis was performed to investigate the clinical correlation between miR-141-3p expression levels and clinicopathological characteristics in PCa patients. The biological roles of miR-141-3p in bone metastasis of PCa were evaluated both in vitro and a mouse intracardial model in vivo. Bioinformatics analysis, Western blot, luciferase reporter and miRNA immunoprecipitation assays were performed to explore and examine the relationship between miR-141-3p and its potential targets. Clinical correlation of miR-141-3p with its targets was examined in clinical PCa tissues.ResultsmiR-141-3p expression is reduced in bone metastatic PCa tissues compared with non-bone metastatic PCa tissues. Low expression of miR-141-3p positively correlates with serum PSA levels, Gleason grade and bone metastasis status in PCa patients. Furthermore, upregulating miR-141-3p suppresses the EMT, invasion and migration of PCa cells in vitro. Conversely, silencing miR-141-3p yields an opposite effect. Importantly, upregulating miR-141-3p dramatically reduces bone metastasis of PC-3 cells in vivo. Our results further show that miR-141-3p inhibits the activation of NF-κB signaling via directly targeting tumor necrosis factor receptor-associated factor 5(TRAF5) and 6 (TRAF6), which further suppresses invasion, migration and bone metastasis of PCa cells. The clinical negative correlation of miR-141-3p expression with TRAF5, TRAF6 and NF-κB signaling activity is demonstrated in PCa tissues.ConclusionOur findings unravel a novel mechanism underlying the bone metastasis of PCa, suggesting that miR-141-3p mimics might represent a potential therapeutic avenue for the treatment of PCa bone metastasis.

Vasculogenic mimicry plays an important role in adrenocortical carcinoma

To determine the prognostic role of vasculogenic mimicry in adrenocortical carcinoma, and to explore its relationship with vascular endothelial growth factor receptor 2 expression.

Downregulation of miR-133a-3p promotes prostate cancer bone metastasis via activating PI3K/AKT signaling

BackgroundBone metastasis is a leading cause of morbidity and mortality in advanced prostate cancer (PCa). Downexpression of miR-133a-3p has been found to contribute to the progression, recurrence and distant metastasis in PCa. However, clinical significance of miR-133a-3p in bone metastasis of PCa, and the biological role of miR-133a-3p and its molecular mechanisms underlying bone metastasis of PCa remain unclear.MethodsmiR-133a-3p expression was evaluated in 245 clinical PCa tissues by real-time PCR. Statistical analysis was performed to evaluate the clinical correlation between miR-133a-3p expression and clinicopathological features, and overall and bone metastasis-free survival in PCa patients. The biological roles of miR-133a-3p in the bone metastasis of PCa were investigated both in vitro and in vivo. Bioinformatics analysis, real-time PCR, western blot and luciferase reporter analysis were applied to demonstrate the relationship between miR-133a-3p and its potential targets. Western blotting and luciferase assays were examined to identify the underlying pathway involved in the anti-tumor role of miR-133a-3p. Clinical correlation of miR-133a-3p with its targets was verified in human PCa tissues.ResultsmiR-133a-3p expression is reduced in PCa tissues compared with the adjacent normal tissues and benign prostate lesion tissues, particularly in bone metastatic PCa tissues. Low expression of miR-133a-3p is significantly correlated with advanced clinicopathological characteristics and shorter bone metastasis-free survival in PCa patients by statistical analysis. Moreover, upregulating miR-133a-3p inhibits cancer stem cell-like phenotypes in vitro and in vivo, as well as attenuates anoikis resistance in vitro in PCa cells. Importantly, administration of agomir-133a-3p greatly suppresses the incidence of PCa bone metastasis in vivo. Our results further demonstrate that miR-133a-3p suppresses bone metastasis of PCa via inhibiting PI3K/AKT signaling by directly targeting multiple cytokine receptors, including EGFR, FGFR1, IGF1R and MET. The negative clinical correlation of miR-133a-3p with EGFR, FGFR1, IGF1R, MET and PI3K/AKT signaling activity is determined in clinical PCa tissues.ConclusionOur results unveil a novel mechanism by which miR-133a-3p inhibits bone metastasis of PCa, providing the evidence that miR-133a-3p may serve as a potential bone metastasis marker in PCa, and delivery of agomir-133a-3p may be an effective anti-bone metastasis therapeutic strategy in PCa.

Transcriptional downregulation of miR-133b by REST promotes prostate cancer metastasis to bone via activating TGF-β signaling

High avidity of bone metastasis is an important characteristic in prostate cancer (PCa). Downexpression of miR-133b has been reported to be implicated in the development, progression and recurrence in PCa. However, clinical significance and biological roles of miR-133b in bone metastasis of PCa remain unclear. Here we report that miR-133b is downregulated in PCa tissues and further decreased in bone metastatic PCa tissues. Downexpression of miR-133b positively correlates with advanced clinicopathological characteristics and shorter bone metastasis-free survival in PCa patients. Upregulating miR-133b inhibits invasion, migration in vitro and bone metastasis in vivo in PCa cells. Mechanistically, we find that miR-133b suppresses activity of TGF-β signaling via directly targeting TGF-β receptor I and II, which further inhibits bone metastasis of PCa cells. Our results further reveal that overexpression of REST contributes to miR-133b downexpression via transcriptional repression in PCa tissues. Importantly, silencing miR-133b enhances invasion and migration abilities in vitro and bone metastasis ability in vivo in REST-silenced PCa cells. The clinical correlation of miR-133b with TGFBRI, TGFBRII, REST and TGF-β signaling activity is verified in PCa tissues. Therefore, our results uncover a novel mechanism of miR-133b downexpression that REST transcriptionally inhibits miR-133b expression in PCa cells, and meanwhile support the notion that administration of miR-133b may serve as a rational regimen in the treatment of PCa bone metastasis.