Role Of Cancerous Inhibitor Of Protein Phosphatase 2A Research Articles

Cancerous Inhibitor of Protein Phosphatase 2A (CIP2A): Could It Be a Promising Biomarker and Therapeutic Target in Parkinson\u2019s Disease?

Parkinson’s disease (PD) is an incurable neurodegenerative disease characterized by aggregation of pathological alpha-synuclein (α-syn) and loss of dopaminergic neuron in the substantia nigra. Inhibition of phosphorylation of the α-syn has been shown to mediate alleviation of PD-related pathology. Protein phosphatase 2A (PP2A), an important serine/threonine phosphatase, plays an essential role in catalyzing dephosphorylation of the α-syn. Here, we identified and validated cancerous inhibitor of PP2A (CIP2A), as a potential diagnostic biomarker for PD. Our data showed that plasma CIP2A concentrations in PD patients were significantly lower compared to age- and sex-matched controls, 1.721 (1.435–2.428) ng/ml vs 3.051(2.36–5.475) ng/ml, p < 0.0001. The area under the curve of the plasma CIP2A in distinguishing PD from the age- and sex-matched controls was 0.776. In addition, we evaluated the role of CIP2A in PD-related pathogenesis in PD cellular and MPTP-induced mouse model. The results demonstrated that CIP2A is upregulated in PD cellular and MPTP-induced mouse models. Besides, suppression of the CIP2A expression alleviates rotenone induced aggregation of the α-syn as well as phosphorylation of the α-syn in SH-SY5Y cells, which is associated with increased PP2A activity. Taken together, our data demonstrated that CIP2A plays an essential role in the mechanisms related to PD development and might be a novel PD biomarker.

Effect of CIP2A and its mechanism of action in the malignant biological behavior of colorectal cancer

BackgroundIncreasing evidence has revealed a close correlation between cancerous inhibitor of protein phosphatase 2A (CIP2A) and cancer progression. CIP2A has been shown to participate in diverse biological processes, such as development, tumorigenic transformation and chemoresistance. However, the functions of CIP2A in colorectal cancer (CRC) and its underlying mechanisms of action are not yet completely understood. The purpose of this study was to explore its clinical significance, function and relevant pathways in CRC.MethodsQuantitative RT-PCR (qRT-PCR), immunohistochemistry (IHC), western blotting and enzyme-linked immunosorbent assay (ELISA) were used to identify the expression of CIP2A in CRC tissues, sera and CRC cell lines. The association between the expressions of CIP2A and patient survival was analyzed using the Kaplan-Meier curves. Additionally, the functional role of CIP2A in the cell lines was identified through small interfering RNA (siRNA)-mediated depletion of the protein followed by analyses of proliferation and xenograft growth in vivo using short hairpin (sh) RNAs. Effects of the C-myc inhibitor 10,058-F4 on the expressions of C-myc, and CIP2A in CRC cell lines and its potential mechanisms of action were investigated. Finally, the potential molecular pathways associated with CIP2A were screened using the phosphokinase array and identified through western blotting.ResultsCIP2A mRNA and protein levels were upregulated in CRC tissues compared to those of the corresponding normal tissues. It can be used as an independent prognostic indicator to determine overall survival (OS) and disease-free survival (DFS). Depletion of CIP2A substantially suppressed the growth of CRC cells and colony formation in vitro, and inhibited the growth of xenograft tumors in vivo. Additionally, the levels of CIP2A in the sera of patients with CRC were higher than those of the control subjects. Multivariate analyses revealed that the levels of CIP2A in the sera were not independent prognostic indicators in patients with CRC. Moreover, 10,058-F4 could effectively inhibit the growth of CRC cells in vitro, which could be correlated with an inhibition in the expressions of C-myc, CIP2A and its downstream regulatory anti-apoptotic proteins. Furthermore, the Human Phosphokinase Antibody Array was used to gain insights into the CIP2A-dependent intermediary signaling pathways. The results revealed that several signaling pathways were affected and the protein levels of p-p53 (S392), p-STAT5a (Y694), Cyclin D1, p-ERK1/2 and p-AKT (T308) had decreased in CIP2A-shRNA group based on the results of the western blot analysis.ConclusionsCIP2A could promote the development of CRC cells and predict poor prognosis in patients with CRC, suggesting that it may serve as a potential prognostic marker and therapeutic target against CRC.-HSBbqB3LRSmwufLCKjmKbVideo Graphical abstract

The expression of cancerous inhibitor protein phosphatase 2A in chronic rhinosinusitis with nasal polyps

Conclusion: The study suggests that cancerous inhibitor of protein phosphatase 2A (CIP2A) expression and eosinophilia associate with chronic rhinosinusitis with nasal polyps with aspirin exacerbated respiratory disease (CRSwNP + AERD). Further studies with a larger sample size are needed to evaluate further the role of CIP2A and related pathways in CRSwNP + AERD.Objectives: Low prostaglandin E2 levels putatively associate with CRSwNP + AERD and decreased c-Myc levels. The aim of this study was to evaluate the expression and revision-predictive role of oncoprotein CIP2A, another c-Myc modulator, in CRSwNP with/without AERD, and in antrochoanal polyps.Method: Ninety retrospective archival objective glasses of nasal polyp tissue from CRSwNP or ACP patients were used for assessing mucosal eosinophilia. Of this population, 90 archival nasal polyp specimens were available for immunohistochemical staining with a polyclonal anti-CIP2A antibody, together with 19 control nasal mucosa specimens. CIP2A staining intensity and tissue eosinophilia were assessed by two blinded observers with a light microscope. Subject characteristics from 90 patients and 19 controls were obtained from patient records and additionally by a questionnaire from controls. The follow-up data was available from patient records of 84 patients and 16 controls.Results: The expression of epithelial CIP2A was detected both in control inferior turbinate mucosa and nasal polyps. The expression was significantly lower in the CRSwNP + AERD group compared to controls and CRSwNP without AERD (p < 0.01). High mucosal eosinophilia associated with CRSwNP (p < 0.01). Neither CIP2A nor eosinophilia predicted the need for revision surgery (p > 0.05), whereas previous surgery, allergic rhinitis, and use of corticosteroids did predict the need for revision surgery (p < 0.05).

Abstract 3557: Cancerous inhibitor of PP2A is a novel molecular target and resistance factor of Lapatinib

Abstract Deregulation of erbB-2 and EGFR is frequently detected in breast cancer, which has been associated with poor prognosis. Lapatinib, an orally active small molecule acting as a dual inhibitor of erbB-2 and EGFR, has been used for the treatment of patients with advanced or metastatic erbB-2+ breast cancer. Lapatinib resistance, however, is emerging as a clinical challenge. Understanding the molecular mechanisms of Lapatinib-mediated anti-cancer activities and identifying relevant resistance factors are of pivotal significance in breast cancer treatment. Cancerous inhibitor of PP2A (CIP2A) is a recently identified oncoprotein that is overexpressed in breast and other types of cancers. Through interacting with protein phosphatase 2A (PP2A), CIP2A regulates c-Myc and factors involved in cell proliferation and survival. This study aimed to investigate the role of CIP2A in Lapatinib-mediated inhibition of erbB-2 overexpressing breast cancer cells. Our data showed that Lapatinib downregulated CIP2A in erbB-2 overexpressing SK-BR-3 and 78617 cells, which was correlated with concurrent inactivation of erbB-2, EGFR, Akt, Erk1/2 and mTOR. Overexpression of CIP2A rendered the cells resistant to Lapatinib induced apoptosis and growth inhibition. Conversely, CIP2A knockdown via siRNA sensitized the cells to Lapatinib-mediated effects. We also demonstrated that Lapatinib-induced downregulation of CIP2A can be abolished by LY294002, suggesting that CIP2A downregulation was regulated by Akt. Analysis with cycloheximide (CHX) and MG132 indicated that Lapatinib modulates CIP2A protein stability and promotes its degradation through prosteasome pathway. More importantly, we found that Lapatinib induced differential downregulation of CIP2A between the parental and Lapatinib-resistant (LR) BT-474 cells. Decrease in CIP2A downregulation in BT-474-LR cells suggests its association with Lapatinib resistance. Knockdown of CIP2A via lentiviral siRNA system significantly sensitized Lapatinib induced growth inhibition and apoptosis. Taken together, our results demonstrate that CIP2A is a molecular target of Lapatinib, which plays a critical role in Lapatinib-induced cellular responses. Lapatinib-induced downregulation of CIP2A involves the inhibition of the Akt-CIP2A feedback loop. Correlation between Lapatinib resistance and decreased CIP2A downregulation, as well as CIP2A knockdown-mediated sensitization of BT-474-LR cells indicate that CIP2A is a resistance factor of Lapatinib. Further investigation on Lapatinib-mediated regulation of CIP2A will advance our understanding of Lapatinib-associated antitumor activities and drug resistance. Citation Format: Ming Zhao, Amanda Blackwelder, Harry Lee, Xiaohe Yang. Cancerous inhibitor of PP2A is a novel molecular target and resistance factor of Lapatinib. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3557. doi:10.1158/1538-7445.AM2015-3557

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 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 regulates cell proliferation via the AKT signaling pathway in human lung cancer.

Cancerous inhibitor of PP2A (CIP2A) is an intracellular endogenous protein phosphatase 2A (PP2A) inhibitor with oncogenic activities. Initially identified as a tumor-associated antigen (TAA) in gastric and liver cancer patients, CIP2A was overexpressed in a variety of cancer types. The overexpression of CIP2A in cancer cells is associated with increased cell proliferation. However, the mechanism of CIP2A in cancer cell proliferation remains poorly understood. In the present study, we reported that CIP2A can regulate AKT phosphorylation at S473 under growth factor stimulation and our results also showed that CIP2A may promote cell proliferation through the AKT signaling pathway. Notably, depletion of CIP2A did not induce a global change of AKT phosphatase activity, which indicated that CIP2A may recognize specific AKT targets and play certain roles in the signaling pathway. In addition, we detected that CIP2A expression was associated with mTOR phosphorylation. Our further analysis corroborated the relationship between CIP2A and AKT-mTOR signaling pathway. Therefore, our study addressed a novel role of CIP2A in mediating cancer progression through interacting with the AKT-mTOR signaling pathway.

Role of CIP2A in the antitumor effect of bortezomib in colon cancer.

Cancerous inhibitor of protein phosphatase 2A (CIP2A) has been identified as an oncoprotein that is able to promote the proliferation of cancer cells. The role of CIP2A in the anticancer activity of bortezomib in colon cancer remains to be elucidated. In the present study, the antitumor effect of bortezomib was investigated and the role of CIP2A in determining the effect on colon cancer cells was identified. In the present study, bortezomib demonstrated an antitumor effect, as observed by WST‑1 assay and flow cytometry. In addition, the mRNA and protein level of CIP2A was inhibited in a dose‑dependent manner by bortezomib with quantitative PCR (qPCR) and western blotting. Furthermore, the inhibition of CIP2A with small interfering RNA by treatment with bortezomib inhibited proliferation, increased apoptosis and attenuated the invasion of the cells. Finally, the invivo data demonstrated that bortezomib was able to decrease the growth of tumors, and that CIP2A was downregulated in the LoVo tumors treated with bortezomib. Therefore, CIP2A was shown to be important in the bortezomib‑induced inhibitory effect on colon cancer.