CIP2A Expression Research Articles

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.

IL-10 Promotes Tumor Aggressiveness via Upregulation of CIP2A Transcription in Lung Adenocarcinoma

Interleukin-10 (IL-10) determines virus persistent infection and promotes viral-associated tumor progression via tumor immune escape. However, the role of IL-10 in tumor progression and prognosis in lung adenocarcinoma remains controversial. To investigate how IL-10 is regulated by HPV E6, IL-10 promoter was constructed to understand which transcriptional factor could be responsible for its transcription. To verify which molecule could be responsible for IL-10-mediated soft agar growth and invasion capability, PCR array and mechanistic strategies were conducted. IL-10 and CIP2A mRNA levels in lung tumors from patients with lung cancer were determined by real-time reverse transcription PCR. The prognostic value of both molecules on survival was estimated by Cox regression model. Mechanistic studies showed that IL-10 protein and mRNA expression was decreased in E6 knockdown TL1 cells and increased in E6- overexpressing TL4 cells. In addition, IL-10 transcription was predominantly regulated by E6-mediated phosphorylation of cAMP response element-binding protein (CREB) and C/enhancer-binding protein β (C/EBPβ) via phosphoinositide 3-kinase (PI3K) signaling pathway. IL-10-mediated tumor aggressiveness in vitro and in vivo occurs through increased CIP2A expression via PI3K signaling pathway. Among patients, IL-10 mRNA expression in lung tumors was positively correlated with CIP2A mRNA expression. Cox-regression analysis showed that IL-10 and CIP2A mRNA levels may independently predict survival in patients with lung adenocarcinoma, especially in patients with E6-positive tumors. IL-10 production from lung tumors and immune cells promotes lung adenocarcinoma aggressiveness and patients with poor survival. We thus suggest that PI3K inhibitor combined with chemotherapy may potentially enhance tumor regression and improve patients' outcome and life quality.

SAT0059 Inhibition of CIP2A facilitate C-MYC independent apoptosis of fibroblast-like synoviocytes in rheumatoid arthritis

BackgroundCancerous inhibitor of protein phosphatase 2A (CIP2A) is a recently identified oncoprotein that leads to cellular proliferation in cancer cells by stabilizing c-Myc protein. The effect of CIP2A in stabilizing...

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.

Clinical implications of CIP2A protein expression in breast cancer

The aim of this work is to study the expression and regulatory effects of CIP2A protein in breast cancer and the correlation between CIP2A protein expression and the prognosis of breast cancer. The CIP2A protein level was detected by immunohistochemistry staining. The relationship between CIP2A protein and clinicopathological parameters of breast cancer was determined. It was observed that 448 (35.00 %) of the 1,280 cases positively expressed CIP2A protein. Univariate analysis indicated that CIP2A expression was related to histological grade, lymph node metastasis, distant metastasis, and triple-negative breast cancer (P = 0.001, 0.001, 0.001, and 0.001, respectively). Spearman correlation analysis showed that CIP2A expression has line correlation with histological grade, lymph node metastasis, distant metastasis, triple-negative breast cancer, and TNM stage (P = 0.03, 0.001, 0.008, 0.001, and 0.001, respectively). After multivariate analysis, tumor size, histological grade, lymph node metastasis, triple-negative breast cancer, distant metastasis, and TNM stage were related to CIP2A expression (P = 0.035, 0.001, 0.028, 0.001, 0.001, and 0.001, respectively). CIP2A expression also significantly related to chemotherapeutic sensitivity of breast cancer in the neoadjuvant chemotherapy. In the Cox regression test, histological grade, lymph node metastasis, triple-negative breast cancer, and TNM stage were detected as the independent prognostic factors (P = 0.001, 0.006, 0.01, 0.011, and 0.001, respectively). CIP2A expression may be a potential biomarker for chemotherapeutic sensitivity and prognosis of breast cancer.

Senescence Sensitivity of Breast Cancer Cells Is Defined by Positive Feedback Loop between CIP2A and E2F1

Senescence induction contributes to cancer therapy responses and is crucial for p53-mediated tumor suppression. However, whether p53 inactivation actively suppresses senescence induction has been unclear. Here, we show that E2F1 overexpression, due to p53 or p21 inactivation, promotes expression of human oncoprotein CIP2A, which in turn, by inhibiting PP2A activity, increases stabilizing serine 364 phosphorylation of E2F1. Several lines of evidence show that increased activity of E2F1-CIP2A feedback renders breast cancer cells resistant to senescence induction. Importantly, mammary tumorigenesis is impaired in a CIP2A-deficient mouse model, and CIP2A-deficient tumors display markers of senescence induction. Moreover, high CIP2A expression predicts for poor prognosis in a subgroup of patients with breast cancer treated with senescence-inducing chemotherapy. Together, these results implicate the E2F1-CIP2A feedback loop as a key determinant of breast cancer cell sensitivity to senescence induction. This feedback loop also constitutes a promising prosenescence target for therapy of cancers with an inactivated p53-p21 pathway. It has been recently realized that most currently used chemotherapies exert their therapeutic effect at least partly by induction of terminal cell arrest, senescence. However, the mechanisms by which cell-intrinsic senescence sensitivity is determined are poorly understood. Results of this study identify the E2F1-CIP2A positive feedback loop as a key determinant of breast cancer cell sensitivity to senescence and growth arrest induction. Our data also indicate that this newly characterized interplay between 2 frequently overexpressed oncoproteins constitutes a promising prosenescence target for therapy of cancers with inactivated p53 and p21. Finally, these results may also facilitate novel stratification strategies for selection of patients to receive senescence-inducing cancer therapies.

Cancerous inhibitor of protein phosphatase 2A determines bortezomib-induced apoptosis in leukemia cells

The multiple cellular targets affected by proteasome inhibition implicate a potential role for bortezomib, a first-in-class proteasome inhibitor, in enhancing antitumor activities in hematologic malignancies. Here, we examined the antitumor activity and drug targets of bortezomib in leukemia cells. Human leukemia cell lines were used for in vitro studies. Drug efficacy was evaluated by apoptosis assays and associated molecular events assessed by Western Blot. Gene silencing was performed by small interference RNA. Drug was tested in vivo in xenograft models of human leukemia cell lines and in primary leukemia cells. Clinical samples were assessed by immunohistochemical staining. Bortezomib differentially induced apoptosis in leukemia cells that was independent of its proteasome inhibition. Cancerous inhibitor of protein phosphatase 2A, a cellular inhibitor of protein phosphatase 2A, mediated the apoptotic effect of bortezomib. Bortezomib increased protein phosphatase 2A activity in sensitive leukemia cells (HL-60 and KG-1), but not in resistant cells (MOLT-3 and K562). Bortezomib's downregulation of cancerous inhibitor of protein phosphatase 2A and phospho-Akt correlated with its drug sensitivity. Furthermore, cancerous inhibitor of protein phosphatase 2A negatively regulated protein phosphatase 2A activity. Ectopic expression of CIP2A up-regulated phospho-Akt and protected HL-60 cells from bortezomib-induced apoptosis, whereas silencing CIP2A overcame the resistance to bortezomib-induced apoptosis in MOLT3 and K562 cells. Importantly, bortezomib exerted in vivo antitumor activity in HL-60 xenografted tumors and induced cell death in some primary leukemic cells. Cancerous inhibitor of protein phosphatase 2A was expressed in leukemic blasts from bone marrow samples. Cancerous inhibitor of protein phosphatase 2A plays a major role in mediating bortezomib-induced apoptosis in leukemia cells.

CIP2A is overexpressed in human ovarian cancer and regulates cell proliferation and apoptosis

CIP2A is a recently characterized oncoprotein which involves in the progression of several human malignancies. This study aimed to investigate its clinical significance and biological function in ovarian cancer. CIP2A expression was analyzed in 152 archived ovarian cancer specimens using immunohistochemistry. One hundred cases (65.79 %) showed CIP2A overexpression, including 63 of 92 serous carcinomas (68.48 %), 21 of 33 endometrioid carcinomas (63.64 %), 12 of 23 mucinous carcinomas (52.17 %), and 4 of 4 clear cell carcinomas (100 %). There is no significant difference of CIP2A expression between serous tumors and all other morphologies combined. CIP2A overexpression positively correlated with advanced FIGO stage (p = 0.0336) and tumor grade (p = 0.0213). siRNA knockdown was performed in A2780 and SKOV3 cell lines. MTT, colony formation assay, and flow cytometry were carried out to assess the role of CIP2A in proliferation, cell cycle, and apoptosis. CIP2A depletion in ovarian cancer cell lines inhibited proliferation, blocked cell cycle progression, and increased paclitaxel-induced apoptosis. Furthermore, CIP2A depletion downregulated cyclin D1, c-myc, phospho-Rb, 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 ovarian cancer.

CIP2A Promotes Proliferation of Spermatogonial Progenitor Cells and Spermatogenesis in Mice

Protein phosphatase 2A (PP2A) is a critical regulator of protein serine/threonine phosphorylation. However, the physiological and developmental roles of different PP2A complexes are very poorly understood. Here, we show that a newly characterized PP2A inhibitory protein CIP2A is co-expressed with ki-67 and with self-renewal protein PLZF in the spermatogonial progenitor cell (SPC) population in the testis. CIP2A and PLZF expression was shown also to correlate Ki-67 expression in human testicular spermatogonia. Functionally, CIP2A mutant mouse testes exhibited smaller number of PLZF-positive SPCs and reduced sperm counts. Moreover, seminiferous tubuli cells isolated from CIP2A mutant mice showed reduced expression of Plzf and other renewal genes Oct-4 and Nanog at mRNA level. However, PLZF-deficient testes did not show altered CIP2A expression. Importantly, spermatogonia-specific restoration of CIP2A expression rescued PLZF expression and sperm production defects observed in CIP2A mutant mice. Taken together, these results reveal first physiological function for an emerging human oncoprotein CIP2A, and provide insights into maintenance of PLZF-positive progenitors. Moreover, demonstration that CIP2A expression can be systematically inhibited without severe consequences to normal mouse development and viability may have clinical relevance regarding targeting of oncogenic CIP2A for future cancer therapies.

CIP2A expression is elevated in cervical cancer

Early detection of cervical cancer is critical for a favorable prognosis. Standard cytological detection methods, such as Pap smear, are highly subjective and HPV detection is not a reliable marker for predicting the malignancy potential of cervical lesions. As a result, there is a demand for a diagnostic assay capable of sensitive and specific detection of cervical cancer. In this preclinical exploratory study, qRT-PCR and western blotting were used to assess expression levels of CIP2A and p16INK4a in cervical tissue samples (n(normal adjacent) = 23, n(tumor) = 29). CIP2A was abundantly expressed in cervical cancer cell lines and was not expressed in normal epithelial cells. CIP2A mRNA levels were higher in cervical tumor tissues in comparison to the level of CIP2A mRNA in normal adjacent tissue from cervical cancer patients. CIP2A protein was specifically expressed in cervical tumor tissues at different cancer grades and stages, and was not observed in normal adjacent tissue. Elevated CIP2A mRNA levels in cervical tissues had a sensitivity of 80% and specificity of 91% and CIP2A protein expression detection had a sensitivity of 83% and specificity of 100%, similar to that of p16INK4a, with no correlation of CIP2A expression with HPV infection, age, race, or other patient characteristics. However the number of samples analyzed in this preliminary study is limited and a large prospective cohort study is necessary to further evaluate CIP2A as a biomarker for cervical cancer.

Involvement of CD147 isoform‑4 in the proliferation of SiHa cells: A possible molecular mechanism of cervical cancer

CD147, a multifunction glycoprotein of the immuno-globulin family, is associated with many types of tumors, and the overexpression of CD147 can enhance malignancy. However, the role of CD147 in cervical cancer remains unclear. In the present study, cervical cancer cells were found to express much more CD147 protein and isoform‑4 than normal cervical cells (P<0.05), suggesting that CD147 and isoform‑4 are involved in cervical cancers. Furthermore, we overexpressed the CD147 isoform‑4 (CD147‑4) in the cervical cancer cell line SiHa by transfection and found that CD147-4 promoted the proliferation of SiHa cells with a considerable proportion of cells in the Sphase in which the expression of CIP2A, Plk and cyclinD1 was up-regulated while the expression of P27 was down-regulated. This may be one of the molecular mechanisms involved in cervical cancer progression by CD147.

Abstract 4194: Constitutive DNA-damage signaling promotes cancer cell proliferation through Chk1-CIP2A pathway independent of ATM-ATR

Abstract DNA damage is a hallmark of malignantly transformed cells. Accordingly, overexpression of the DNA damage activated kinases has been observed in different human cancers. However, it is unclear whether constitutive DNA damage present in unperturbed cancer cells promotes tumourigenesis. Here we show that increased activity of DNA damage sensitive kinase Chk1 promotes proliferation of several cancer cell types by stimulating expression of CIP2A protein. Either chemical or genetic inhibition of Chk1, and not of ATM-ATR, results in potent inhibition of CIP2A protein expression levels. Importantly, Chk1 siRNA-elicited inhibition of cell proliferation and clonogenic growth is rescued by overexpression of CIP2A from a heterologous promoter. Moreover, in clinical (human) tumor samples there is a significant association between CIP2A and Chk1 expression in both ovarian and gastric cancers. Intriguingly, meta-analysis of seventeen published genome wide studies on different types of cancers unveils a striking similarity in the gene expression patterns of both CIP2A and Chk1. Amongst these, 12/17 studies show overexpression (top 10%) of both these proteins. Additionally, similarly to CIP2A, increased Chk1 expression is shown to correlate with tumor progression in human cancer. In summary, these results identify a novel function for DNA damage kinase Chk1 in regulation of the human oncoprotein CIP2A. In general, these results provide an unprecented molecular mechanism by which constitutive DNA damage present in cancer cells promotes tumourigenesis. Additionally, as CIP2A is not significantly expressed in most of the normal human tissues, it is proposed that targeting of CIP2A might abrogate the Chk1-mediated support of proliferation without concerns related to anticancer therapy directly targeting Chk1. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4194. doi:10.1158/1538-7445.AM2011-4194

CIP2A is over‐expressed in acute myeloid leukaemia and associated with HL60 cells proliferation and differentiation

CIP2A is a newly identified inhibitor of PP2A. It can stabilize c-Myc and promote anchorage-independent cell growth and tumour formation. CIP2A is over-expressed in some solid tumours although its expression in acute myeloid leukaemia (AML) is still unknown. CIP2A mRNA and protein expressions were determined in bone marrow mononuclear cells of both patients with AML and healthy controls using reverse transcription polymerase chain reaction and Western blot, respectively. We used siRNA to knock-down CIP2A expression in HL60 cells and then examined its potential roles during the pathological progression of AML. CIP2A mRNA was present in 54 of 70 (77.14%) patients with newly diagnosed AML and in 11 of 14 (70.86%) patients with relapsed AML, which was significantly higher than complete remission specimens and healthy controls (P<0.001). Knock-down of CIP2A in HL60 cells slowed down cell proliferation, decreased clonogenic activity and promoted cell differentiation. These results suggest that CIP2A is over-expressed in patients with newly diagnosed/relapsed AML and the expression of CIP2A could have potential use as a clinical marker for AML relapse after treatment. The high expression of CIP2A in HL60 cells may be related to active cell proliferation and arrest of cell differentiation. This study may shed light on the molecular function of CIP2A in myeloid leukemogenesis.

CIP2A expression is increased in prostate cancer

BackgroundThe CIP2A protein is a recently characterized oncoprotein which inhibits protein phosphatase 2A activity. Expression of CIP2A has been detected in several carcinomas, but its expression and significance in prostate cancer has not been examined so far.MethodsExpression of the CIP2A protein was studied using immunohistochemistry in prostate cancer (n = 59) and in benign prostatic hyperplasia (n = 20) specimens. The CIP2A staining scores were compared with several clinicopathological parameters.ResultsExpression of CIP2A was increased in prostate cancer epithelium as compared with the benign hyperplastic epithelium (p < 0.001). The expression of CIP2A was associated with high Gleason scores (p < 0.001) and among patients treated with radical prostatectomy, CIP2A expression was associated with pre-treatment risk stratification (p = 0.011) and pathological T-class (p = 0.031). No statistically significant association was detected between CIP2A expression and prostate specific antigen concentrations.ConclusionsExpression of the CIP2A protein is increased in prostate cancer specimens and its expression is associated with poorly differentiated and high-risk tumors.

Abstract 4645: CIP2A is a marker of reduced survival in serous ovarian cancer patients

Abstract Cancerous inhibitor of PP2A (CIP2A) is a recently identified oncoprotein, but its role in ovarian cancer is not known. We analyzed CIP2A protein expression in 562 consecutive serous ovarian cancer patients, of which 524 were scored successfully and analyzed for presence of CIP2A immunopositivity using tissue microarrays. The association of CIP2A expression with survival was evaluated according to the Kaplan-Meier method. We found strong CIP2A positive immunostaining in 212 (40.4%) specimens, 222 (42.4%) were weakly positive, while the rest (n = 90, 17.2%) were immunonegative for CIP2A protein. Our results demonstrate that CIP2A immunopositivity is a marker of reduced overall survival in ovarian cancer patients (P &amp;lt; 0.0001). In addition, positive CIP2A expression was significantly more frequent in specimens with high grade (P &amp;lt; 0.0001), advanced stage (P = 0.0005), aberrant p53 immunoreactivity (P &amp;lt; 0.0001), high proliferation index (P &amp;lt; 0.0001), and aneuploidy (P = 0.001). Interestingly, in subgroups of patients with favorable clinical factors (i.e. low stage and optimal debulking surgery) CIP2A expression was strongly associated with reduced survival (P &amp;lt; 0.0001 for both parameters). This shows that CIP2A could be used to predict biological behavior in the group of patients with otherwise favorable prognosis. In conclusion, our results show that CIP2A protein expression is a novel marker of reduced survival in patients with serous ovarian carcinoma. Furthermore, these results suggest that CIP2A characterizes the aggressive type of this disease even within subgroups with initially favorable prognosis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4645.