Expression of CIP2A in renal cell carcinomas correlates with tumour invasion, metastasis and patients' survival

Exploring the composition of protein-ligand binding sites for cancerous inhibitor of PP2A (CIP2A) by inhibitor guided binding analysis: paving a new way for the Discovery of drug candidates against triple negative breast cancer (TNBC)

Triple-negative breast cancer (TNBC) is associated with high-grade invasive carcinoma leading to a 10% to 15% death rate in younger premenopausal women. Targeting cancerous inhibitors of protein phosphatase (CIP2A) has been a highly effective approach for exploring therapeutic drug candidates. Lapatinib, a dual tyrosine kinase inhibitor, has shown promising inhibition properties by inducing apoptosis in TNBC carcinogenesis in vivo. Despite knowledge of the 3D structure of CIP2A, no reports provide insight into CIP2A ligand binding sites. To this effect, we conducted in silico site identification guided by lapatinib binding. Four of the five sites identified were cross-validated, and the stem domain revealed more excellent ligand binding affinity. The binding affinity of lapatinib in these sites was further computed using the Molecular Mechanics/Poisson-Boltzmann Surface Area (MM/PBSA) approach. According to MM/PBSA//200 ns MD simulations, lapatinib exhibited a higher binding affinity against CIP2A in site 2 with ΔG critical values of -37.1 kcal/mol. The steadiness and tightness of lapatinib with CIP2A inside the stem domain disclosed glutamic acid-318 as the culprit amino acid with the highest electrostatic energy. These results provide clear information on the CIP2A domain capable of ligand binding and validate lapatinib as a promising CIP2A inhibitor in TNBC carcinogenesis.

From Basic Science to Clinical Practice: The Role of Cancerous Inhibitor of Protein Phosphatase 2A (CIP2A)/p90 in Cancer

Cancerous inhibitor of protein phosphatase 2A (CIP2A), initially reported as a tumor-associated antigen (known as p90), is highly expressed in most solid and hematological tumors. The interaction of CIP2A/p90, protein phosphatase 2A (PP2A), and c-Myc can hinder the function of PP2A toward c-Myc S62 induction, thus stabilizing c-Myc protein, which represents a potential role of CIP2A/p90 in tumorigeneses such as cell proliferation, invasion, and migration, as well as cancer drug resistance. The signaling pathways and regulation networks of CIP2A/p90 are complex and not yet fully understood. Many previous studies have also demonstrated that CIP2A/p90 can be used as a potential therapeutic cancer target. In addition, the autoantibody against CIP2A/p90 in sera may be used as a promising biomarker in the diagnosis of certain types of cancer. In this Review, we focus on recent advances relating to CIP2A/p90 and their implications for future research.

Integrative assessment of CIP2A overexpression and mutational effects in human malignancies identifies possible deleterious variants

KIAA1524 is the gene encoding the human cancerous inhibitor of PP2A (CIP2A) protein which is regarded as a novel target for cancer therapy. It is overexpressed in 65%-90% of tissues in almost all studied human cancers. CIP2A expression correlates with cancer progression, disease aggressivity in lung cancer besides poor survival and resistance to chemotherapy in breast cancer. Herein, a pan-cancer analysis of public gene expression datasets was conducted showing significant upregulation of CIP2A in cancerous and metastatic tissues. CIP2A overexpression also correlated with poor survival of cancer patients. To determine the non-coding variants associated with CIP2A overexpression, 5'UTR and 3'UTR variants were annotated and scored using RegulomeDB and Enformer deep learning model. The 5'UTR variants rs1239349555, rs1576326380, and rs1231839144 were predicted to be potential regulators of CIP2A overexpression scoring best on RegulomeDB annotations with a high "2a" rank of supporting experimental data. These variants also scored the highest on Enformer predictions. Analysis of the 3'UTR variants of CIP2A predicted rs56255137 and rs58758610 to alter binding sites of hsa-miR-500a-5 and (hsa-miR-3671, hsa-miR-5692a) respectively. Both variants were also found in linkage disequilibrium with rs11709183 and rs147863209 respectively at r² ≥ 0.8. The aforementioned variants were found to be eQTL hits significantly associated with CIP2A overexpression. Further, analysis of rs11709183 and rs147863209 revealed a high "2b" rank on RegulomeDB annotations indicating a probable effect on DNAse transcription factors binding. The MuTarget analysis indicated that somatic mutations in TP53 are significantly associated with upregulated CIP2A in human cancers. Analysis of missense SNPs on CIP2A solved structure predicted seven deleterious effects. Four of these variants were also predicted as structurally and functionally destabilizing to CIP2A including; rs375108755, rs147942716, rs368722879, and rs367941403. Variant rs1193091427 was predicted as a potential intronic splicing mutation that might be responsible for the novel CIP2A variant (NOCIVA) in multiple myeloma. Finally, Enrichment of the Wnt/β-catenin pathway within the CIP2A regulatory gene network suggested potential of therapeutic combinations between FTY720 with Wnt/β-catenin, Plk1 and/or HDAC inhibitors to downregulate CIP2A which has been shown to be essential for the survival of different cancer cell lines.

CIP2A regulates MYC translation (via its 5'UTR) in colorectal cancer

BACKGROUND

Deregulated expression of MYC is a driver of colorectal carcinogenesis, suggesting that decreasing MYC expression may have significant therapeutic value. CIP2A is an oncogenic factor that regulates MYC expression. CIP2A is overexpressed in colorectal cancer (CRC), and its expression levels are an independent marker for long-term outcome of CRC. Previous studies suggested that CIP2A controls MYC protein expression on a post-transcriptional level.

METHODS

To determine the mechanism by which CIP2A regulates MYC in CRC, we dissected MYC translation and stability dependent on CIP2A in CRC cell lines.

RESULTS

Knockdown of CIP2A reduced MYC protein levels without influencing MYC stability in CRC cell lines. Interfering with proteasomal degradation of MYC by usage of FBXW7-deficient cells or treatment with the proteasome inhibitor MG132 did not rescue the effect of CIP2A depletion on MYC protein levels. Whereas CIP2A knockdown had marginal influence on global protein synthesis, we could demonstrate that, by using different reporter constructs and cells expressing MYC mRNA with or without flanking UTR, CIP2A regulates MYC translation. This interaction is mainly conducted by the MYC 5'UTR.

CONCLUSIONS

Thus, instead of targeting MYC protein stability as reported for other tissue types before, CIP2A specifically regulates MYC mRNA translation in CRC but has only slight effects on global mRNA translation. In conclusion, we propose as novel mechanism that CIP2A regulates MYC on a translational level rather than affecting MYC protein stability in CRC.

Prognostic Significance of CIP2A in Esophagogastric Junction Adenocarcinoma: A Study of 65 Patients and a Meta-Analysis

Background

The expression of the cancerous inhibitor protein phosphatase 2A (CIP2A) appears to be predictive of the prognosis of various solid tumors. However, the association between this protein and the risk of esophagogastric junction adenocarcinoma (EGJA) remains unclear. We investigated CIP2A expression and its clinical significance in EGJA and conducted a meta-analysis to explore the relationship between CIP2A and the prognosis of patients with solid tumors.

Methods

Immunohistochemistry (IHC) was performed to detect the expression of CIP2A in EGJA. Kaplan-Meier estimation, Cox analysis, and ROC curves were performed to analyze the survival of patients and the prognostic factors. In the meta-analysis, we searched relevant publications in several widely used databases and used 15 studies (2348 patients).

Results

IHC demonstrated that CIP2A was elevated in EGJA and correlated with poor survival as an independent indicator. It could forecast the survival more precisely when combined with the grade, which is another independent prognosis marker of EGJA. Meta-analysis demonstrated that the associations between the expression of CIP2A and the prognosis were detected for overall survival (HR = 1.98, 95%CI = 1.69‐2.32), disease-specific survival (HR = 1.72, 95%CI = 1.50‐1.97), and time to tumor progression (pooled HR = 1.95, 95%CI = 1.56‐2.43).

Conclusion

High expression of CIP2A was a poor indicator of the prognosis of EGJA, and CIP2A may be a new biomarker for the diagnosis and treatment of EGJA. The meta-analysis suggested that CIP2A expression can be a predictive marker of overall survival, disease-specific survival, and time to tumor progression in patients with solid tumors.

Downregulation of CIP2A inhibits cancer cell proliferation and vascularization in renal clear cell carcinoma

BACKGROUND

CIP2A has been proved to play a role as an oncogene in various types of malignancies while its functionality in renal clear cell carcinoma has not been investigated. Our study aimed to investigate the role of CIP2A in renal clear cell carcinoma and to explore the possible mechanisms.

METHODS

A total of 80 patients with renal clear cell carcinoma and 32 healthy people were included in the study. Expression of CIP2A was detected by qRT-PCR. CIP2A silencing renal clear cell carcinoma cell line was established. Its effects on cell proliferation and migration were verified by CCK-8 assay and Transwell cell assay, respectively. The effects of CIP2A overexpression on AKT and VEGF were investigated.

RESULTS

CIP2A expression level was increased in tumor tissues compared to adjacent healthy tissues. Serum levels of CIP2A protein were higher in cancer patients than in healthy controls, and serum levels of CIP2A protein were increased with increased stage of primary tumor. Serum CIP2A protein can be used to accurately predict renal clear cell carcinoma and its prognosis. CIP2A siRNA silencing inhibited tumor cell proliferation, and treatment with Akt activator reduced this inhibitory effect. CIP2A siRNA silencing decreased the expression level of VEGF and phosphorylation levels of AKT in renal clear cell carcinoma cells, while AKT activator treatment showed no significant effects on CIP2A expression.

CONCLUSION

Downregulation of CIP2A can inhibit cancer cell proliferation and vascularization in renal clear cell carcinoma through inactivation of the Akt pathway and its downstream VEGF.

HP-1 inhibits the progression of ccRCC and enhances sunitinib therapeutic effects by suppressing EMT

Trametes robiniophila Murr (Huaier) has been used for many years as an adjuvant treatment for tumors. Sunitinib is the first-line therapy for end-stage renal cancer, but its side effects and drug resistance limit its clinical application. Cell counting kit- 8 (CCK-8), colony formation, scratch, and Transwell assays showed that Huaier polysaccharide (HP-1) reduced tumor progression. Its combination with sunitinib elicited stronger antitumor effects, including induction of apoptosis and cycle arrest. HP-1-induced effects depended on CIP2A downregulation and suppression of the EMT process. Moreover, qPCR and western blotting experiments showed that CIP2A downregulation was particularly pronounced after treatment with the combination therapy and was associated with EMT suppression. In addition, the HP-1/sunitinib combination inhibited the PI3K/Akt/VEGFR pathway, reducing the expression of pathway-related proteins. The HP-1-induced enhancement of sunitinib effects on tumor growth were also observed in vivo in a xenograft mouse model. Overall, these results indicated that HP-1 exerted antitumor effects against clear cell renal cell carcinoma (ccRCC) and enhanced the therapeutic efficacy of sunitinib.

CIP2A overexpression in Taiwanese oral cancer patients

Introduction: Oral cancer is a prevalent form of cancer worldwide, particularly in Taiwan, and mechanisms involved in oral squamous cell carcinoma (OSCC) progression remain relatively unknown. Cancerous inhibitor of protein phosphatase 2A (CIP2A), an oncoprotein, is aberrantly expressed in many human malignant tumors including oral cancer. However, the expression and role played by CIP2A in oral cancer pathogenesis remain obscure. Methods: In this study, immunohistochemistry was used to analyze CIP2A expression between OSCC tissues and their adjacent noncancerous tissues. Furthermore, associations between CIP2A expression and histopathological parameters were investigated. Results: In this study, we showed that CIP2A was overexpressed in most of the OSCC tissues. High CIP2A expression was significantly associated with moderate/poor tumor differentiation (P=0.02). No significant association was found between CIP2A expression and other clinical parameters. Kaplan-Meier analysis revealed that high CIP2A expression showed poorer survival rates than those with low CIP2A expression (P=0.047). Multivariate Cox regression analysis indicated that CIP2A expression, N stage, American Joint Committee on Cancer stage and clinical therapy were independent prognostic factors for survival. Conclusion: Thus, our study suggests that CIP2A is an independent prognostic marker for OSCC and a novel target for OSCC treatment.

CIP2A Promotes Proliferation, Invasion and Chemoresistance to Cisplatin in Renal Cell Carcinoma

CIP2A is a well-known oncoprotein whose expression is elevated in multiple human solid tumor types. However, its role in renal cell carcinoma (RCC) development is poorly understood. Thus, in our present study, we used the renal cancer cell lines 786-O, A498 and CAKI-1 and the renal epithelial cell line HK-2 to clarify the function of CIP2A in RCC. We found that CIP2A expression is much higher in the RCC cells than in the normal renal epithelial cell. Lentivirus covered coding region CIP2A cDNA sequence and CIP2A siRNA were used to up and down regulate CIP2A expression in vitro. We found that overexpression of CIP2A promoted G1/S transition and cell proliferation. In addition, up-regulation of CIP2A significantly enhanced the invasion and migration capabilities of the cells. Furthermore, CIP2A promoted epithelial-mesenchymal transformation (EMT) and chemoresistance to cisplatin in RCC cells. Taken together, our findings demonstrate that CIP2A plays an important role in proliferation, invasion and chemoresistance to cisplatin in RCC cells. CIP2A may serve as an ideal molecular target for RCC therapeutics.

Increase in CIP2A expression is associated with cisplatin chemoresistance in gastric cancer

BACKGROUND

The cancerous inhibitor of protein phosphatase 2A (CIP2A) is an oncoprotein which involves in the progression of several human malignancies. Development of cisplatin (DDP) resistance is the obstacle to an effective control of gastric cancer (GC) clinically.

OBJECTIVE

We thus assessed whether CIP2A expression is associated with sensitivity of GC to DDP.

METHODS

Real-time quantitative PCR, immunohistochemical analysis, or western blotting was performed to detect CIP2A expression in GC patients' tissues. SGC7901/DDP cells were transfected with CIP2A siRNA. MTT assay was used to determine the DDP-sensitivity of cells. Flow cytometry was used to measure cell apoptosis.

RESULTS

CIP2A has higher expression in DDP-resistant GC patients. DDP-resistant GC patients with high CIP2A expression presented with poorer overall survival rates than those with low CIP2A expression. CIP2A knockdown in DDP-resistant GC cells resulted in attenuated proliferative abilities and increased apoptosis level. CIP2A depletion sensitizes DDP-resistant cells to DDP and CIP2A overexpression antagonizes DDP-sensitive cells to DDP. CIP2A influences the expression of multidrug resistance-related proteins in GC cells.

CONCLUSIONS

Our results suggested that CIP2A oncoprotein plays an important role in DDP resistance of GC and could serve as a novel therapeutic target for the treatment of GC patients with DDP resistance.

Prognostic significance of CIP2A expression in solid tumors: A meta-analysis

CIP2A, cancerous inhibitor of protein phosphatase 2A, was initially recognized as an oncoprotein. Recently several studies revealed that CIP2A could function as a prognosis biomarker, however, the result remained not comprehensive, partly due to small number of patients included individually. Here we carried out a meta-analysis of published studies to assess the prognostic significance of CIP2A in solid tumors. All eligible studies were identified through searching PubMed, Embase and Web of Science database. In this meta-analysis, 22 studies involving 4,579 participants were included, and we verified that CIP2A over-expression was significantly related with poor overall survival (pooled HR = 1.844, 95% CI = 1.528–2.225, P<0.001) and short disease free survival (pooled HR = 1.808, 95% CI = 1.591–2.055, P<0.001) in solid tumors. Additionally, subgroup analysis suggested that the trend of a poor overall survival with an increased CIP2A expression was present in East-Asian and European patients, as well as in lung cancer and colorectal cancer. To sum up, CIP2A over-expression was associated with poor survival in human solid tumors and might be a predictive factor of poor prognosis.

Ethoxysanguinarine inhibits viability and induces apoptosis of colorectal cancer cells by inhibiting CIP2A

Cancerous inhibitor of protein phosphatase 2A (CIP2A) an endogenous inhibitor of protein phosphatase 2A (PP2A), which can promote proliferation and transformation of several cancer types, has been shown to be a target for tumor therapy. The present study investigated the effects and underlying mechanisms of action of a novel natural compound, ethoxysanguinarine (Eth), on colorectal cancer (CRC) cells. MTT assay and flow cytometric assay found that Eth inhibited the viability and induced the apoptosis of the CRC cells. The inhibition of viability and activation of apoptosis was mediated through the Eth-induced decrease in CIP2A expression. Knockdown of CIP2A by RNA interference sensitized, whereas overexpression of CIP2A antagonized, Eth-induced viability inhibition and apoptosis. Furthermore, western blot analysis suggested that Eth inhibited phosphorylation of CIP2A downstream molecule protein kinase B via the activation of PP2A. CRC xenograft tests also confirmed the antitumor effect of Eth in vivo. These results advance our understanding of Eth-induced viability inhibition and apoptosis, implying the requirement for further investigation of Eth as a CIP2A inhibitor for cancer therapies.

Cucurbitacin B induces inhibitory effects via CIP2A/PP2A/Akt pathway in glioblastoma multiforme

Cancerous inhibitor of protein phosphatase 2A (CIP2A) is a human oncoprotein that is overexpressed in multiple types of tumors and promotes the proliferation and transformation of cancer cells. However, whether CIP2A can be a new drug target for human glioblastoma multiforme (GBM) is largely unclear. In the present study, we demonstrated that the overexpression of CIP2A promotes invasive behavior in GBM, and a natural compound, cucurbitacin B (CuB), shows an anti-proliferative and anti-invasion effect in GBM cell lines. CuB effectively induces apoptosis, downregulates CIP2A expression and its downstream signaling molecule, phospho-Akt, and upregulates protein phosphatase 2A (PP2A) activity. Overexpression of CIP2A reduced CuB-inhibited growth and invasion in GBM cells. Silencing CIP2A enhanced CuB-induced invasion inhibition and apoptosis in GBM. CuB combined with cisplatin synergistically inhibited GBM cells. CuB also inhibited tumor growth in murine models. Western blot results further revealed that CuB downregulates CIP2A, and phospho-Akt in vivo. In summary, inhibition of CIP2A determines the effects of CuB-induced invasive behavior inhibition and apoptosis in GBM cells. These characteristics render CuB as a promising candidate drug for further development and for designing new effective CIP2A inhibitors.

High expression of CIP2A protein is associated with tumor aggressiveness in stage I-III NSCLC and correlates with poor prognosis

The aim of this work was to examine the expression of cancerous inhibitor of protein phosphatase 2A (CIP2A) in non-small cell lung cancer (NSCLC) and analyze its correlation with clinical outcomes. CIP2A protein levels were detected by immunohistochemistry (IHC). One hundred and eighty-four of 209 (88.3%) primary stage I-III NSCLC specimens and 4 of 38 (10.5%) adjacent normal lung tissue specimens expressed CIP2A protein. High expression of CIP2A was detected in 38.8% (81/209) of the NSCLC specimens. Patients diagnosed histologically with late-stage NSCLC (p<0.001) and malignant nodes (p=0.001) exhibited high CIP2A expression. Univariate analysis using the log-rank test identified CIP2A expression as a prognostic predictor for overall survival (p=0.005). In multivariate analyses using the Cox regression test, CIP2A expression, T stage, N stage, histological type, and chemotherapy were identified as independent prognostic factors (p=0.007, 0.001, 0.003, <0.001, and <0.001, respectively). Furthermore, Kaplan-Meier survival curves demonstrated that high CIP2A expression indicated poor prognosis in the subgroup of patients with squamous cell carcinoma (p=0.008). Similar results were noted in the subgroup of patients with adenocarcinoma, but the results did not reach statistical significance (p=0.084). We also used univariate analysis and multivariate analysis to assess the prognostic factors for overall survival in the subgroup of patients who received postoperative chemotherapy. CIP2A expression was also an independent prognostic factor in NSCLC patients who received postoperative chemotherapy (p=0.009), along with histological type (p=0.001) and N stage (p=0.034). In conclusion, adding to the accumulating evidence, our research suggested that the CIP2A expression is associated with aggressiveness and correlates with poor prognosis in NSCLC. Our findings also indicated that CIP2A might be a potential therapeutic target against NSCLC.

Acidic leucine-rich nuclear phosphoprotein-32A (ANP32A) association with lymph node metastasis predicts poor survival in oral squamous cell carcinoma patients

Acidic leucine-rich nuclear phosphoprotein-32A (ANP32A) is a multifunctional protein aberrantly expressed in various types of cancers. However, its expression pattern and clinical significance in oral squamous cell carcinoma (OSCC) remains unclear. In this study, we immunohistochemically investigated the expression pattern of ANP32A in 259 OSCC patients and the results were correlated with clinicopathological factors using Allred, Klein and Immunoreactive scoring (IRS) system. Our data indicated that high expression of ANP32A was significantly associated with N stage and tumor differentiation status in OSCC patients. High ANP32A expression with N2/N3 stage had an increased mortality risk than low ANP32A expressing OSCC patients with N0/N1 stage. Functional studies revealed that knockdown of ANP32A significantly decreased the migration and invasion ability thereby concomitantly increasing E-cadherin and decreasing Slug, Claudin-1 and Vimentin expression in vitro. These results suggest that ANP32A is commonly increased in oral squamous cell carcinoma and ANP32A protein could act as a potential biomarker for prognosis assessment of oral cancer patients with lymph node metastasis.

Overexpression of CIP2A is associated with poor prognosis in multiple myeloma

Cancerous inhibitor of protein phosphatase 2A (CIP2A), an endogenous protein phosphatase 2A (PP2A) inhibitor, has been identified as an oncoprotein in promoting cancer initiation and progression of several types of cancer. However, the expression and the role played by CIP2A in the pathogenesis of multiple myeloma (MM) remain unclear. In this study, we showed that CIP2A was overexpressed in human MM cell lines and MM patients' bone marrow tissues. Clinicopathologic analysis showed that CIP2A expression was significantly correlated with clinical stage and percent of plasma cells in bone marrow. Kaplan-Meier analysis revealed that patients with high CIP2A expression presented with poorer overall survival rates than those with low CIP2A expression. Moreover, CIP2A knockdown in MM cells resulted in attenuated proliferative abilities. In addition, CIP2A depletion sensitizes dexamethasone (Dex)-resistant cells to Dex. The effect of CIP2A on proliferation and Dex therapy was mediated by the inhibition of PP2A, which in turn activated Akt. In vivo studies confirmed that CIP2A regulated MM tumorigenesis and the phosphorylation of Akt. Taken together, our results suggest that CIP2A oncoprotein plays an important role in MM progression and could serve as a prognosis marker and a novel therapeutic target for the treatment of patients with MM.

Arctigenin inhibits triple-negative breast cancers by targeting CIP2A to reactivate protein phosphatase 2A

We have shown that a novel STAT3 inhibitor arctigenin (Atn) induces significant cytotoxicity in triple-negative breast cancer (TNBC) cells. This study further delineated molecular mechanisms where by Atn triggered cytotoxicity in TNBC cells. We found Atn can also inhibit metastasis in TNBC cells through cancerous inhibitor of protein phosphatase 2A (CIP2A) pathway. CIP2A is an endogenous inhibitor of protein phosphatase 2A (PP2A), which can increase the migration and invasion of various cancer cells. PP2A is a tumor suppressor, which is functionally defective in various cancers. Atn-induced metastasis inhibition was associated with reactivation of PP2A, downregulation of CIP2A and Akt phosphorylation. Silencing CIP2A enhanced Atn-induced metastasis inhibition and apoptosis in TNBCs. Furthermore, ectopic expression of CIP2A or inhibition of PP2A in TNBC cells abolished the effects of Atn. In conclusion, we found that enhancement of PP2A activity by inhibition of CIP2A, at least in part, promotes the anti-metastasis effect induced by Atn. Our findings disclose the novel therapeutic mechanism of this targeted agent, and suggest the therapeutic potential and feasibility of developing PP2A enhancers as a novel anticancer strategy.

Panel of autoantibodies against multiple tumor-associated antigens for detecting gastric cancer

Gastric cancer is the second leading cause of cancer death in the world, and effective diagnosis is extremely important for good outcome. We assessed the diagnostic potential of an autoantibody panel that may provide a novel tool for the early detection of gastric cancer. We analyzed data from patients with gastric cancer and normal controls in test and validation cohorts. Autoantibody levels were measured against a panel of six tumor‐associated antigens (TAAs) by ELISA: p53, heat shock protein 70, HCC‐22‐5, peroxiredoxin VI, KM‐HN‐1, and p90 TAA. We assessed serum autoantibodies in 100 participants in the test cohort. The validation cohort comprised 248 participants. Autoantibodies to at least one of the six antigens showed a sensitivity/specificity of 49.0% (95% confidence interval [CI], 39.2–58.8%)/92.4% (95% CI, 87.2–97.6%), and 52.0% (95% CI, 42.2–61.8%)/90.5% (95% CI, 84.8–96.3%) in the test and validation cohorts, respectively. In the validation cohort, no significant differences were seen when patients were subdivided based on age, sex, depth of tumor invasion, lymph node metastasis, distant metastasis, peritoneal dissemination, or TNM stage. Patients who were positive for more than two antibodies in the panel tended to have a worse prognosis than those who were positive for one or no antibody. Measurement of autoantibody response to multiple TAAs in an optimized panel assay to discriminate patients with early stage gastric cancer from normal controls may aid in the early detection of gastric cancer.

Expression of cancerous inhibitor of protein phosphatase 2A in human triple negative breast cancer correlates with tumor survival, invasion and autophagy

Cancerous inhibitor of protein phosphatase 2A (CIP2A) is a recently characterized oncoprotein which is involved in the progression of several human malignancies. The present study aimed to investigate its biological function in human triple negative breast cancer (TNBC). The expression of CIP2A in TNBC cells was examined and it was observed that CIP2A was elevated in the TNBC cell line compared with poorly invasive breast cancer cells. CIP2A depletion in TNBC cell lines inhibited proliferation, and induced apoptosis and autophagy. In addition, CIP2A depletion inhibited invasion and migration of TNBC cells. Furthermore, CIP2A depletion downregulated Akt/mTOR/P70S6K phosphorylation. These results validate the role of CIP2A as a invasion-associated oncoprotein and established CIP2A as a promising therapeutic target of TNBC.

Gambogenic acid induces proteasomal degradation of CIP2A and sensitizes hepatocellular carcinoma to anticancer agents

Cancerous inhibitor of protein phosphatase 2A (CIP2A) is an oncoprotein that is overexpressed in many human malignancies. It regulates phosphorylated AKT and stabilizes c‑Myc in cell proliferation and tumor formation, suggesting that CIP2A plays an essential role in the development of cancer. In the present study, we report that a natural compound, gambogenic acid (GEA), induced the degradation of CIP2A via the ubiquitin‑proteasome pathway. Interestingly, the combination of GEA and proteasome inhibitors potentiated the accumulation of ubiquitinated CIP2A and aggresome formation. In addition, GEA exhibited an inhibitory effect on cell proliferation and CIP2A‑downstream signaling molecules (c‑Myc and pAKT). Furthermore, GEA and CIP2A silencing enhanced the chemosensitivity of hepatocellular carcinoma cells to anticancer agents, suggesting that a combination of a CIP2A inhibitor and anticancer agents could be a valuable clinical therapeutic strategy. These results indicate that GEA is a CIP2A inhibitor that interferes with the ubiquitination and destabilization of CIP2A, providing a promising strategy to enhance the combinational therapy for hepatocellular carcinoma.

RhoB Acts as a Tumor Suppressor That Inhibits Malignancy of Clear Cell Renal Cell Carcinoma

This study aims to investigate the biological role of RhoB in clear cell renal cell carcinoma (ccRCC). The expression of RhoB was examined in specimens of patients and cell lines by Western blot and Immunohistochemistry. The correlation between RhoB expression and clinicopathologic variables was also analyzed. The effects of RhoB on cell proliferation, cell cycle, cell apoptosis, and invasion/migration were detected by over-expression and knockdown of RhoB level in ccRCC cells via plasmids and RNAi. The results showed that RhoB was low-expressed in ccRCC surgical specimens and cell lines compared with adjacent normal renal tissues and normal human renal proximal tubular epithelial cell lines (HKC), and its protein expression level was significantly associated with the tumor pathologic parameter embracing tumor size(P = 0.0157), pT stage(P = 0.0035), TNM stage(P = 0.0024) and Fuhrman tumor grade(P = 0.0008). Further, over-expression of RhoB remarkably inhibited the cancer cell proliferation, colony formation and promoted cancer cell apoptosis, and aslo reduced the invasion and migration ability of ccRCC cells. Interestingly, up-regulation of RhoB could induce cell cycle arrest in G2/M phase and led to cell cycle regulators(CyclineB1,CDK1) and pro-apoptotic protein(casp3,casp9) aberrant expression. Moreover, knockdown of RhoB in HKC cells promoted cell proliferation and migration. Taken together, our study indicates that RhoB expression is decreased in ccRCC carcinogenesis and progression. Up-regulation of RhoB significantly inhibits ccRCC cell malignant phenotype. These findings show that RhoB may play a tumor suppressive role in ccRCC cells, raising its potential value in futural therapeutic target for the patients of ccRCC.

Cancerous inhibitor of protein phosphatase 2A contributes to human papillomavirus oncoprotein E7-induced cell proliferation via E2F1

Cancerous inhibitor of protein phosphatase 2A (CIP2A) is a recently identified oncoprotein that is overexpressed in many human malignant tumors including cervical cancer. Human papillomavirus (HPV) oncoprotein E7 is the key transformation factor in cervical cancer. Our previous data showed a positive association of CIP2A and HPV-16E7 protein levels; however, how CIP2A is regulated by HPV-E7 and the roles of CIP2A in HPV-E7-mediated cell proliferation are unknown. In this study, we demonstrated that HPV-16E7 protein significantly upregulating CIP2A mRNA and protein expression depended on retinoblastoma protein pRb rather than p130. CIP2A siRNA knockdown in HPV-E7-expressing cells inhibited cell proliferation, DNA synthesis and G1/S cell cycle progression. CIP2A siRNA decreased the protein levels of cyclin-dependent kinase 1 (Cdk1), Cdk2 and their partner cyclin A2, with no change in levels of Cdk4, Cdk6 and their partner cyclin D1. The downregulation of Cdk1 and Cdk2 was independent of c-Myc; instead, E2F1 was the main target of CIP2A in this process, as overexpression of E2F1 rescued the inhibitory effects of CIP2A siRNA knockdown on cell proliferation and G1 arrest of HPV-E7-expressing cells. Our studies reveal a novel function of CIP2A in HPV-16E7-mediated cell proliferation.

CIP2A overexpression induces autoimmune response and enhances JNK signaling pathway in human lung cancer

Background

Cancerous inhibitor of PP2A (CIP2A) is a recently characterized oncoprotein, which promotes cancer cell proliferation. But the role of CIP2A in lung cancer progression is still not well understood.

Methods

The expression level of CIP2A in lung cancer tissues was examined by immunohistochemistry. CIP2A-associated cell proliferation was performed by knock down or overexpression of CIP2A in lung cancer cells. Phospho-array was used to screen kinase candidates related to expression change of CIP2A. Western-blot and luciferase reporter assay were used to validate phospho-array results.

Results

Overexpression of CIP2A in lung cancer not only triggers immune response in lung cancer patients but also promotes lung cancer cell proliferation. By phospho-array, several kinase candidates were identified, one of which is c-Jun activated kinases (JNK). The knock down of CIP2A decreased JNK phosphorylation, and the phosphorylation of downstream transcriptional factors, ATF2 and c-Jun, whose transcriptional activity were decreased as well. Furthermore, the expression level of CIP2A also affected the phosphorylation of the upstream kinase of JNK, MKK4/MKK7. At last, treatment with JNK inhibitor partially abolished CIP2A-induced cell proliferation.

Conclusion

CIP2A is a tumor-associated autoantigen in lung cancer, which promote lung cancer proliferation partially through MKK4/7-JNK signaling pathway.

Somatostatin Derivate (smsDX) Attenuates the TAM-Stimulated Proliferation, Migration and Invasion of Prostate Cancer via NF-κB Regulation

Tumor development and progression are influenced by macrophages of the surrounding microenvironment. To investigate the influences of an inflammatory tumor microenvironment on the growth and metastasis of prostate cancer, the present study used a co-culture model of prostate cancer (PCa) cells with tumor-associated macrophage (TAM)-conditioned medium (MCM). MCM promoted PCa cell (LNCaP, DU145 and PC-3) growth, and a xenograft model in nude mice consistently demonstrated that MCM could promote tumor growth. MCM also stimulated migration and invasion in vitro. Somatostatin derivate (smsDX) significantly attenuated the TAM-stimulated proliferation, migration and invasion of prostate cancer. Immunohistochemistry revealed that NF-κB was over-expressed in PCa and BPH with chronic inflammatory tissue specimens and was positively correlated with macrophage infiltration. Further investigation into the underlying mechanism revealed that NF-κB played an important role in macrophage infiltration. SmsDX inhibited the paracrine loop between TAM and PCa cells and may represent a potential therapeutic agent for PCa.

CIP2A mediates prostate cancer progression via the c-Myc signaling pathway

Recent evidence suggests that cancerous inhibitor of protein phosphatase 2A (CIP2A) is an oncoprotein that acts as a novel therapeutic target in a variety of tumors. In this study, we investigated the clinical significance of CIP2A and its function in our large collection of prostate samples. Between August 2000 and December 2013, 126 patients with histologically confirmed prostate cancer (PCa) and 92 with benign prostate hyperplasia (BPH) were recruited into the study. Quantitative real-time PCR (RT-PCR), Western blot, and immunohistochemistry analyses were used to quantify CIP2A expression in PCa clinical samples and cell lines. The relationships between CIP2A expression and clinicopathological features were analyzed. The functional role of CIP2A in PCa cells was evaluated by small interfering RNA-mediated depletion of the protein followed by analyses of cell proliferation and invasion. High expression of CIP2A staining was 86.51 % (109/126) in 126 cases of PCa and 17.39 % (16/92) in 92 cases of BPH; the difference of CIP2A expression between PCa and BPH was statistically significant. CIP2A was significantly elevated in all five PCa cell lines when compared to the RWPE-1 cells at both the messenger RNA (mRNA) and protein levels. Silencing of CIP2A inhibited the proliferation of DU-145 cells which have a relatively high level of CIP2A in a time- and concentration-dependent manner, and the invasion and migration of DU-145 cells were distinctly suppressed. Furthermore, CIP2A knockdown led to substantial reductions in c-Myc levels in DU-145 cells, but no significant change in phosphorylated Akt expression after CIP2A knockdown in DU-145 cells. Our data suggest that the pathogenesis of human PCa maybe mediated by CIP2A, and CIP2A inhibition treatment may provide a promising strategy for the antitumor therapy of PCa, and thus, CIP2A could represent selective targets for the molecularly targeted treatments of PCa.

CIP2A mediates prostate cancer progression via the c-MYC signaling pathway

Recent evidence suggests that cancerous inhibitor of protein phosphatase 2A (CIP2A) is an oncoprotein that acts as a novel therapeutic target in a variety of tumors. In this study, we investigated the clinical significance of CIP2A and its function in our large collection of prostate samples. Between August 2000 and December 2013, 126 patients with histologically confirmed PCa and 92 with benign prostate hyperplasia (BPH) were recruited into the study. Quantitative RT-PCR, Western blot, and immunohistochemistry analyses were used to quantify CIP2A expression in PCa clinical samples and cell lines. The relationships between CIP2A expression and clinicopathological features were analyzed. The functional role of CIP2A in PCa cells was evaluated by small interfering RNA-mediated depletion of the protein followed by analyses of cell proliferation and invasion. High expression of CIP2A staining was 86.51 % (109/126) in 126 cases of PCa and 17.39 % (16/92) in 92 cases of BPH, and the difference of CIP2A expression between PCa and BPH was statistically significant. CIP2A was significantly elevated in all five PCa cell lines when compared to the RWPE-1 cells at both the messenger RNA (mRNA) and protein levels. Silencing of CIP2A inhibited the proliferation of DU-145 cells which have a relatively high level of CIP2A in a time- and concentration-dependent manner, and the invasion and migration of DU-145 cells were distinctly suppressed. Furthermore, CIP2A knockdown led to substantial reductions in c-Myc levels in PCa cell lines, but no significant change in phosphorylated Akt expression after CIP2A knockdown in DU-145 cells. Our data suggest that the pathogenesis of human PCa maybe mediated by CIP2A, and CIP2A inhibition treatment may provide a promising strategy for the antitumor therapy of PCa, and thus CIP2A could represent selective targets for the molecularly targeted treatments of PCa.

Oncogenic nexus of cancerous inhibitor of protein phosphatase 2A (CIP2A): an oncoprotein with many hands

Oncoprotein CIP2A a Cancerous Inhibitor of PP2A forms an "oncogenic nexus" by virtue of its control on PP2A and MYC stabilization in cancer cells. The expression and prognostic function of CIP2A in different solid tumors including colorectal carcinoma, head and neck cancers, gastric cancers, lung carcinoma, cholangiocarcinoma, esophageal cancers, pancreatic carcinoma, brain cancers, breast carcinoma, bladder cancers, ovarian carcinoma, renal cell carcinomas, tongue cancers, cervical carcinoma, prostate cancers, and oral carcinoma as well as a number of hematological malignancies are just beginning to emerge. Herein, we reviewed the recent progress in our understanding of (1) how an "oncogenic nexus" of CIP2A participates in the tumorigenic transformation of cells and (2) how we can prospect/view the clinical relevance of CIP2A in the context of cancer therapy. The review will try to understand the role of CIP2A (a) as a biomarker in cancers and evaluate the prognostic value of CIP2A in different cancers (b) as a therapeutic target in cancers and (c) in drug response and developing chemo-resistance in cancers.

Overexpression of CIP2A is an independent prognostic indicator in nasopharyngeal carcinoma and its depletion suppresses cell proliferation and tumor growth

BACKGROUND

Cancerous inhibitor of protein phosphatase 2A (CIP2A) is an oncoprotein that acts as a prognostic marker for several human malignancies. In this study, we investigated the clinical significance of CIP2A and its function in nasopharyngeal carcinoma (NPC).

METHODS

Quantitative RT-PCR, western blot, and immunohistochemistry analyses were used to quantify CIP2A expression in NPC cell lines and clinical samples. Kaplan-Meier curves were used to estimate the association between CIP2A expression and patient survival. The functional role of CIP2A in NPC cell lines was evaluated by small interfering RNA-mediated depletion of the protein followed by analyses of cell proliferation and xenograft growth.

RESULTS

CIP2A levels were upregulated in NPC cell lines and clinical samples at both the mRNA and protein levels (P < 0.01). Patients with high CIP2A expression had poorer overall survival (HR, 1.98; 95% CI, 1.16-3.34; P = 0.01) and poorer disease-free survival (HR, 1.68; 95% CI, 1.07-2.62; P = 0.02) rates than patients with low CIP2A expression. In addition, CIP2A expression status was an independent prognostic indicator for NPC patients. The depletion of CIP2A expression inhibited c-Myc protein expression in NPC cell lines, suppressed cell viability, colony formation, and anchorage-independent growth in vitro, and inhibited xenograft tumor growth in vivo.

CONCLUSIONS

Our data demonstrate that high CIP2A expression in patients was associated with poor survival in NPC, and depletion of CIP2A expression inhibited NPC cell proliferation and tumor growth. Thus, these results warrant further investigation of CIP2A as a novel therapeutic target for the treatment of NPC.

Ethoxysanguinarine Induces Inhibitory Effects and Downregulates CIP2A in Lung Cancer Cells

Cancerous inhibitor of protein phosphatase 2A (CIP2A) is an oncoprotein that is able to stabilize c-Myc oncogenic transcription factor and promote proliferation and transformation of cells. CIP2A is overexpressed in many primary tumors, and pharmacological inactivation of CIP2A is an emerging concept for the development of novel anticancer agents. In this study, we demonstrate that overexpression of CIP2A predicts poor prognosis in lung cancer, and a natural compound, ethoxysanguinarine (ESG), effectively downregulates CIP2A protein and its downstream signaling molecules, c-Myc and pAkt, and induces protein phosphatase 2A (PP2A) activity. ESG inhibits proliferation and induces apoptosis of lung cancer cells, and enhances the effects of cisplatin on malignant cells. Taken together, our findings demonstrate that CIP2A is inversely associated with the clinical outcome of lung cancer, and ESG can serve as a lead compound for the development of CIP2A inhibitor for cancer therapies.

Autoantibody response to a novel tumor-associated antigen p90/CIP2A in breast cancer immunodiagnosis

There is an urgent need to identify relevant tumor markers showing high sensitivity and specificity for early immunodiagnosis of breast cancer. Autoantibodies directed against tumor-associated antigens (TAAs) have been shown to be relevant tumor markers. The purpose of this study was to evaluate whether autoantibodies to a tumor-associated antigen p90/CIP2A can be used as diagnostic markers in breast cancer. In this study, autoantibody responses to p90/CIP2A were evaluated by enzyme-linked immunosorbent assay (ELISA), western blotting, and indirect immunofluorescence assay in sera from patients with breast cancer and normal human individuals. The results have demonstrated that p90/CIP2A can induce a relatively higher frequency of autoantibody response in breast cancer (19.1%) compared to the sera of normal individuals (2.3%). The frequency of p90/CIP2A expression in breast cancer tissues was significantly higher than that in adjacent normal tissues (P < 0.01). Our preliminary results suggest that autoantibodies against p90/CIP2A may be a useful serum biomarker for early stage breast cancer screening and diagnosis.

Expression and prognostic significance of CIP2A in cutaneous malignant melanoma

OBJECTIVE

We investigated the expression and clinical significance of Cancerous inhibitor of protein phosphatase 2A (CIP2A) in Cutaneous malignant melanoma (CMM).

METHODS

CIP2A expression was analyzed by immunohistochemistry and western blot. We tested the invasion and migration capability of A375 cells with Matrigel invasion assay, Scratch migration assay and Matrigel migration assay after down-regulating CIP2A expression using siRNA.

RESULTS

CIP2A immunostaining level was correlated with Breslow thickness, Clark's Level and lymphovascular invasion. High-CIP2A expression implied poor survival for patients. Downregulation of CIP2A attenuated metastasis of CMM cells.

CONCLUSIONS

CIP2A may serve as a novel marker to predict the prognosis for CMM patients.

CIP2A modulates cell-cycle progression in human cancer cells by regulating the stability and activity of Plk1

Abnormal cell-cycle control can lead to aberrant cell proliferation and cancer. The oncoprotein cancerous inhibitor of protein phosphatase 2A (CIP2A) is an inhibitor of protein phosphatase 2A (PP2A) that stabilizes c-Myc. However, the precise role of CIP2A in cell division is not understood. Herein, we show that CIP2A is required for mitotic progression by regulating the polo-like kinase (Plk1). With mitotic entry, CIP2A translocated from the cytoplasm to the nucleus, where it was enriched at spindle poles. CIP2A depletion delayed mitotic progression, resulting in mitotic abnormalities independent of PP2A activity. Unexpectedly, CIP2A interacted directly with the polo-box domain of Plk1 during mitosis. This interaction was required to maintain Plk1 stability by blocking APC/C-Cdh1-dependent proteolysis, thereby enhancing the kinase activity of Plk1 during mitosis. We observed strong correlation and in vivo interactions between these two proteins in multiple human cancer specimens. Overall, our results established a novel function for CIP2A in facilitating the stability and activity of the pivotal mitotic kinase Plk1 in cell-cycle progression and tumor development.

Cancerous inhibitor of protein phosphatase 2A (CIP2A) protein is involved in centrosome separation through the regulation of NIMA (never in mitosis gene A)-related kinase 2 (NEK2) protein activity

Cancerous inhibitor of protein phosphatase 2A (CIP2A) is overexpressed in most human cancers and has been described as being involved in the progression of several human malignancies via the inhibition of protein phosphatase 2A (PP2A) activity toward c-Myc. However, with the exception of this role, the cellular function of CIP2A remains poorly understood. On the basis of yeast two-hybrid and coimmunoprecipitation assays, we demonstrate here that NIMA (never in mitosis gene A)-related kinase 2 (NEK2) is a binding partner for CIP2A. CIP2A exhibited dynamic changes in distribution, including the cytoplasm and centrosome, depending on the cell cycle stage. When CIP2A was depleted, centrosome separation and the mitotic spindle dynamics were impaired, resulting in the activation of spindle assembly checkpoint signaling and, ultimately, extension of the cell division time. Our data imply that CIP2A strongly interacts with NEK2 during G2/M phase, thereby enhancing NEK2 kinase activity to facilitate centrosome separation in a PP1- and PP2A-independent manner. In conclusion, CIP2A is involved in cell cycle progression through centrosome separation and mitotic spindle dynamics.

CIP2A influences survival in colon cancer and is critical for maintaining Myc expression

The cancerous inhibitor of protein phosphatase 2A (CIP2A) is an oncogenic factor that stabilises the c-Myc protein. CIP2A is overexpressed in several tumours, and expression levels are an independent marker for long-term outcome. To determine whether CIP2A expression is elevated in colon cancer and whether it might serve as a prognostic marker for survival, we analysed CIP2A mRNA expression by real-time PCR in 104 colon cancer samples. CIP2A mRNA was overexpressed in colon cancer samples and CIP2A expression levels correlated significantly with tumour stage. We found that CIP2A serves as an independent prognostic marker for disease-free and overall survival. Further, we investigated CIP2A-dependent effects on levels of c-Myc, Akt and on cell proliferation in three colon cancer cell lines by silencing CIP2A using small interfering (si) and short hairpin (sh) RNAs. Depletion of CIP2A substantially inhibited growth of colon cell lines and reduced c-Myc levels without affecting expression or function of the upstream regulatory kinase, Akt. Expression of CIP2A was found to be dependent on MAPK activity, linking elevated c-Myc expression to deregulated signal transduction in colon cancer.

CIP2A is overexpressed in osteosarcoma and regulates cell proliferation and invasion

Cancerous inhibitor of protein phosphatase 2A (CIP2A) is a newly characterized oncoprotein involved in a variety of malignant tumors. However, its expression pattern and biological functions in osteosarcoma remain unclear. In the present study, CIP2A expression was analyzed in 51 human osteosarcoma specimens using immunohistochemistry. CIP2A siRNA was used in the MG-63 cell line, and the effect of CIP2A depletion on cell proliferation and invasion was evaluated. We found that CIP2A was overexpressed in 76.5 % (39/51) of osteosarcoma tissues, while normal bone tissues showed negative CIP2A expression. In addition, the positive rate of CIP2A expression was higher in stage IIB osteosarcoma than stage IIA cases. Knockdown of the CIP2A expression significantly reduced osteosarcoma cell proliferation and invasion, with decreased c-Myc expression and p-AKT expression. CIP2A depletion also facilitated apoptosis and inhibited MMP9 mRNA expression. Taken together, our data identified CIP2A as a critical oncoprotein involved in cell proliferation and invasion, which could serve as a therapeutic target in osteosarcoma.

Fusogenic-oligoarginine peptide-mediated delivery of siRNAs targeting the CIP2A oncogene into oral cancer cells

Despite a better understanding of the pathogenesis of oral cancer, its treatment outcome remains poor. Thus, there is a need for new therapeutic strategies to improve the prognosis of this disease. RNA interference (RNAi) appears to be a promising therapeutic tool for the treatment of many diseases, including oral cancer. However, an obstacle for RNAi-mediated therapies has been delivery, in particular, the retention of small interfering RNAs (siRNAs) in endosomes and their subsequent degradation in lysosomes, resulting in inefficient gene silencing. Thus, the current study examined the feasibility of designing and utilizing a peptide, termed 599, consisting of a synthetic influenza virus-derived endosome-disruptive fusogenic peptide sequence and a stretch of cationic cell-penetrating nona(D-arginine) residues, to deliver siRNAs into oral cancer cells and induce silencing of the therapeutic target, CIP2A, an oncoprotein overexpressed in various human malignancies including oral cancer. Increasing the 599 peptide-to-siRNA molar ratio demonstrated a higher binding capacity for siRNA molecules and enhanced siRNA delivery into the cytoplasm of oral cancer cells. In fact, quantitative measurements of siRNA delivery into cells demonstrated that a 50∶1 peptide-to-siRNA molar ratio could deliver 18-fold higher amounts of siRNAs compared to cells treated with siRNA alone with no significant long-term cytotoxic effects. Most importantly, the 599 peptide-mediated siRNA delivery promoted significant CIP2A mRNA and protein silencing which resulted in decreased oral cancer cell invasiveness and anchorage-independent growth. Together, these data demonstrate that a chimeric peptide consisting of a fusogenic sequence, in combination with cell-penetrating residues, can be used to effectively deliver siRNAs into oral cancer cells and induce the silencing of its target gene, potentially offering a new therapeutic strategy in combating oral cancer.

CIP2A expression and prognostic role in patients with esophageal adenocarcinoma

CIP2A is overexpressed in many cancers, including esophageal squamous cell carcinoma. The regulation of c-MYC and CIP2A expression is characterized by a positive feedback mechanism facilitating the expression of both of them and accelerating cancer cell proliferation in gastric cancer. Increased CIP2A expression is a predictor of poor survival in some cancers. The incidence of positive CIP2A immunostaining and its association with c-MYC and its predictive value in esophageal adenocarcinoma are unknown. All esophageal adenocarcinoma patients from 1990 to 2007 with sufficient material for analysis of CIP2A and c-MYC in two university hospitals were included in the study. In addition, biopsies from Barrett's epithelium from the cancer patients and control tissue from normal esophageal mucosa adjacent to the tumor were included. CIP2A was moderately or strongly positive in 77.9 %, and c-MYC in 93.8 % of the cancer specimens. These frequencies were statistically different from the expression in normal esophageal epithelium. In addition, there was a positive correlation between CIP2A and c-MYC expression (p = 0.018). According to adjusted Cox regression survival analysis, CIP2A and c-MYC had no effect on survival. However, among patients with stage IVA-IVB cancer, there was a trend toward poor prognosis in CIP2A-positive patients. The expression of CIP2A and c-MYC was associated with each other, and their overexpression was found in most cases of esophageal adenocarcinoma. However, CIP2A and c-MYC had no effect on survival.

Genomics and epigenomics of clear cell renal cell carcinoma: recent developments and potential applications

Majority of clear cell renal cell carcinomas (ccRCCs) are diagnosed in the advanced metastatic stage resulting in dramatic decrease of patient survival. Thereby, early detection and monitoring of the disease may improve prognosis and treatment results. Recent technological advances enable the identification of genetic events associated with ccRCC and reveal significant molecular heterogeneity of ccRCC tumors. This review summarizes recent findings in ccRCC genomics and epigenomics derived from chromosomal aberrations, DNA sequencing and methylation, mRNA, miRNA expression profiling experiments. We provide a molecular insight into ccRCC pathology and recapitulate possible clinical applications of genomic alterations as predictive and prognostic biomarkers.

CIP2A expression is associated with altered expression of epithelial-mesenchymal transition markers and predictive of poor prognosis in pancreatic ductal adenocarcinoma

CIP2A has been regarded as a novel potential therapeutic target for multiple cancers. The aim of this study was to detect CIP2A expression in pancreatic ductal adenocarcinoma (PDA) and to analyze its association with prognosis of PDA patients. The expression of CIP2A and three epithelial-mesenchymal transition (EMT)-related proteins (E-cadherin, N-cadherin, and vimentin) was examined in 96 PDA tissue samples by immunohistochemistry. Fifty-four cases (56.3 %) were defined as positive for CIP2A expression. Immunohistochemistry showed that CIP2A expression was correlated with poor tumor differentiation, TNM stage, and lymph node metastasis. Kaplan-Meier survival analysis showed that patients with CIP2A-positive expression showed lower overall survival rate than those with CIP2A-negative expression. Multivariate analysis showed that CIP2A expression was an independent prognostic factor for PDA patients. Furthermore, positive expression of CIP2A was strongly associated with loss of the epithelial marker E-cadherin and acquisition of the expression of the mesenchymal markers N-cadherin and vimentin. These findings suggest that CIP2A might promote EMT and progression in PDA, and thus may be a potential therapeutic target for patients with PDA.

Tumor suppressor miR-375 regulates MYC expression via repression of CIP2A coding sequence through multiple miRNA-mRNA interactions

miR-375 interacts with five conserved target sites in the CIP2A coding region, whereas the CIP2A 3′ UTR is not conserved across mammalian species. Reexpression of the tumor suppressor miR-375 in cancer cells represses the expression of CIP2A, resulting in a decrease in the MYC protein level and leading to reduced cell proliferation, migration, and invasion.

MicroRNAs (miRNAs) are small, noncoding RNAs involved in posttranscriptional regulation of protein-coding genes in various biological processes. In our preliminary miRNA microarray analysis, miR-375 was identified as the most underexpressed in human oral tumor versus controls. The purpose of the present study is to examine the function of miR-375 as a candidate tumor suppressor miRNA in oral cancer. Cancerous inhibitor of PP2A (CIP2A), a guardian of oncoprotein MYC, is identified as a candidate miR-375 target based on bioinformatics. Luciferase assay accompanied by target sequence mutagenesis elucidates five functional miR-375–binding sites clustered in the CIP2A coding sequence close to the C-terminal domain. Overexpression of CIP2A is clearly demonstrated in oral cancers, and inverse correlation between miR-375 and CIP2A is observed in the tumors, as well as in NCI-60 cell lines, indicating the potential generalized involvement of the miR-375–CIP2A relationship in many other cancers. Transient transfection of miR-375 in oral cancer cells reduces the expression of CIP2A, resulting in decrease of MYC protein levels and leading to reduced proliferation, colony formation, migration, and invasion. Therefore this study shows that underexpression of tumor suppressor miR-375 could lead to uncontrolled CIP2A expression and extended stability of MYC, which contributes to promoting cancerous phenotypes.

Expression and biological role of CIP2A in human astrocytoma

Cancerous inhibitor of protein phosphatase 2A (CIP2A) is a recently characterized oncoprotein involved in the progression of several human malignancies. The present study aimed to investigate the clinical significance and biological function of CIP2A in astrocytoma. CIP2A expression was analyzed in 135 archived astrocytoma specimens using immunohistochemistry. Of these specimens, 75 cases (55.6%) overexpressed CIP2A. The CIP2A overexpression was observed to be positively correlated with advanced tumor grade (P<0.001). siRNA-mediated knockdown of CIP2A was performed in A172 and U87 cell lines. MTT, colony formation and soft agar colony formation assays and Annexin V/propidium iodide analysis were performed to assess the role of CIP2A in cell proliferation and apoptosis. CIP2A depletion in the astrocytoma cell lines inhibited cell growth, reduced anchorage‑independent cell growth and increased apoptosis. In addition, CIP2A depletion increased caspase‑3 cleavage and downregulated c‑Myc, Bcl‑2 and phospho‑Akt expression. These results validate the role of CIP2A as a clinically relevant oncoprotein and establish CIP2A as a promising therapeutic target of astrocytoma.