CIP2A interacts with AKT1 to promote the malignant biological behaviors of oral squamous cell carcinoma by upregulating the GSK‑3β/β‑catenin pathway

Oral squamous cell carcinoma (OSCC) is one of the most common malignancies worldwide, which is associated with a poor prognosis. The present study aimed to investigate the role of cancerous inhibitor of protein phosphatase 2A (CIP2A) in OSCC and its regulatory effect on AKT1. Firstly, CIP2A and AKT1 expression in OSCC cells was detected by western blotting. After silencing CIP2A, cell viability and cell proliferation were assessed using the Cell Counting Kit-8 assay and 5-ethynyl-2'-deoxyuridine staining. Cell apoptosis was evaluated by TUNEL staining and the expression of apoptosis-related proteins was assessed using western blotting. Wound healing, Transwell and tube formation assays were performed to evaluate CAL-27 cell migration, invasion and human umbilical vein endothelial cell (HUVEC) tube formation. The interaction between CIP2A and AKT1 was identified by co-immunoprecipitation (co-IP). In addition, AKT1 was overexpressed in CIP2A-silenced CAL-27 cells to perform rescue experiments to analyze the malignant biological functions of CAL-27 cells. Finally, the expression of proteins in the glycogen synthase kinase (GSK)-3β/β-catenin pathway was determined by western blot analysis. Markedly elevated CIP2A and AKT1 expression was observed in OSCC cells. CIP2A knockdown inhibited the viability, proliferation, migration and invasion, and promoted the apoptosis of CAL-27 cells. Concurrently, CIP2A loss-of-function attenuated tube formation. Results of Co-IP confirmed there was an interaction between CIP2A and AKT1. Rescue experiments suggested that AKT1 overexpression alleviated the inhibitory effects of CIP2A knockdown on the viability, proliferation, migration and invasion of CAL-27 cells, as well as tube formation in HUVECs . Additionally, CIP2A silencing significantly downregulated phosphorylated-GSK-3β and β-catenin expression, which was reversed by AKT1 overexpression. In conclusion, CIP2A could interact with AKT1 to promote the malignant biological behaviors of OSCC cells by upregulating the GSK-3β/β-catenin pathway. These findings may provide a targeted therapy for OSCC treatment.

Polyphyllin I and VII potentiate the chemosensitivity of A549/DDP cells to cisplatin by enhancing apoptosis, reversing EMT and suppressing the CIP2A/AKT/mTOR signaling axis

Poor response and resistance to cisplatin (DDP)-based chemotherapy frequently leads to treatment failure in advanced non-small cell lung cancer (NSCLC). The underlying molecular mechanism is extremely complex and currently remains unclear. The overexpression of cancerous inhibitor of protein phosphatase 2A (CIP2A) indicates poor prognosis and promotes the epithelial-to-mesenchymal transition (EMT) and metastasis. The EMT has been reported to promote drug resistance in numerous previous studies. CIP2A and its downstream protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway also plays a role in mediating DDP resistance. Polyphyllin I (PPI) and polyphyllin VII (PPVII) are natural components extracted from Paris polyphylla that display anti-cancer properties. In the present study, the chemosensitizing effects of PPI and PPVII were investigated in the DDP-resistant NSCLC cell line A549/DDP, as well as the underlying molecular mechanisms. The results demonstrated that PPI and PPVII could significantly inhibit cell proliferation and enhance the sensitivities of A549/DDP cells to DDP. When assessing the underlying molecular mechanism, it was revealed that PPI and PPVII enhanced DDP-induced apoptosis in A549/DDP cells via p53 upregulation and the caspase-dependent pathway. Furthermore, PPI and PPVII reversed the EMT and suppressed CIP2A and its downstream AKT/mTOR signaling cascade in A549/DDP cells. Overall, the results from the present study demonstrated that PPI and PPVII may function as chemosensitizers by enhancing apoptosis via the p53 pathway, reversing EMT and suppressing the CIP2A/AKT/mTOR signaling axis, and the combination with DDP may be a promising strategy for the development of new therapeutic agents.

MicroRNA-218 inhibits the cell proliferation and migration in clear cell renal cell carcinoma through targeting cancerous inhibitor of protein phosphatase 2A

MicroRNAs (miRs) have emerged as critical modulators of tumor initiation and progression in numerous types of human cancer, including clear cell renal cell carcinoma (ccRCC), which is the most common subtype of renal cell carcinoma. Cancerous inhibitor of protein phosphatase 2A (CIP2A) is a newly characterized oncoprotein and its overexpression has been reported to promote cellular epithelial-mesenchymal transition and the tumor progression of ccRCC. The present study examined the effects of miR-218 on CIP2A expression in ccRCC cells. The results demonstrated that the expression level of miR-218 was lower in ccRCC tissues compared with that in adjacent non-tumor renal tissues. In addition, it was identified that miR-128 could directly bind to the 3'-untranslated region of CIP2A. Furthermore, a negative correlation between the expression levels of miR-218 and CIP2A was detected in ccRCC. Additionally, the downregulation of CIP2A or overexpression of miR-218 in ccRCC cells was revealed to inhibit cell proliferation and migration. In summary, these data suggest that miR-218 serves a role in the regulation of CIP2A and elucidate its consequences on tumor progression, tumor cell proliferation and migration. These results indicate that miR-218 may exhibit potential as a molecular target for the treatment of ccRCC.

Cancerous inhibitor of protein phosphatase 2A regulates cisplatin resistance in ovarian cancer

Ovarian cancer is the most aggressive type of gynecological cancer. The cause of the poor survival rate is the development of chemotherapy resistance to platinum-based therapies, including cisplatin. The present study aimed to investigate the mechanism of cancerous inhibitor of protein phosphatase 2A (CIP2A)-induced chemoresistance in ovarian cancer. The present study initially investigated the expression of CIP2A in the ovarian tumor tissue, cisplatin-sensitive SKOV-3 cell line, and cisplatin-resistant ovarian carcinoma SKOV-3CDDP/R cell line. In addition, CIP2A was knocked down using small interference RNA in ovarian cancer cells and the chemosensitivity of these cells was analyzed. The results demonstrated that CIP2A expression was significantly higher in patients with ovarian cancer and in the cisplatin-resistant ovarian carcinoma SKOV-3CDDP/R cell line at the mRNA and protein levels. The proliferation and chemosensitivity were decreased and enhanced, respectively, when CIP2A was knocked down. CIP2A silencing significantly promoted the apoptosis induced by cisplatin in SKOV-3CDDP/R cells, suggesting that CIP2A participated in the cisplatin resistance of ovarian cancer cells and that CIP2A silencing enhanced the apoptosis induced by cisplatin. CIP2A may be considered as a potential candidate for modulating cisplatin therapy in ovarian cancer.

MicroRNA-383-5p acts as a prognostic marker and inhibitor of cell proliferation in lung adenocarcinoma by cancerous inhibitor of protein phosphatase 2A

Lung cancer is the leading cause of cancer-associated mortality worldwide. MicroRNAs (miRNAs/miRs) serve a role in the occurrence and development of lung cancer. The aim of the present study was to analyze the expression and function of the proliferation-associated miR-383-5p in lung adenocarcinoma (LAC). Samples of human LAC and matched adjacent normal lung tissues were surgically removed, and miR-383-5p expression and the pathological characteristics of lung adenocarcinoma were investigated. The present study revealed that miR-383-5p expression level was significantly decreased in LAC tissues and its expression levels were markedly associated with tumor size and differentiation. Overexpression of miR-383-5p in A549 and H1299 LAC cell lines inhibited cell proliferation by G₁ cell cycle phase arrest and induction of apoptosis. Cancerous inhibitor of protein phosphatase 2A (CIP2A), a potential target gene of miR-383-5p, was inversely associated with miR-383-5p expression level in LAC tissues and cell lines. Furthermore, the results of the present study demonstrated that CIP2A was directly regulated by miR-383-5p and the restoration of CIP2A expression reversed the inhibitory effects of miR-383-5p on LAC cell proliferation. In conclusion, the results of the present study demonstrated that miR-383-5p was downregulated in LAC tissues. By targeting CIP2A, miR-383-5p exerts its anti-proliferative function in LAC, suggesting its use a potential novel potential prognostic biomarker and therapeutic target for LAC.

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.

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).

Understanding the transcriptional regulation of cervix cancer using microarray gene expression data and promoter sequence analysis of a curated gene set

Cervical cancer, the malignant neoplasm of the cervix uteri is the second most common cancer among women worldwide and the top-most cancer in India. Several factors are responsible for causing cervical cancer, which alter the expression of oncogenic genes resulting in up or down-regulation of gene expression and inactivation of tumor-suppressor genes/gene products. Gene expression is regulated by interactions between transcription factors (TFs) and specific regulatory elements in the promoter regions of target genes. Thus, it is important to decipher and analyze TFs that bind to regulatory regions of diseased genes and regulate their expression. In the present study, computational methods involving the combination of gene expression data from microarray experiments and promoter sequence analysis of a curated gene set involved in the cervical cancer causation have been utilized for identifying potential regulatory elements. Consensus predictions of two approaches led to the identification of twelve TFs that might be crucial to the regulation of cervical cancer progression. Subsequently, TF enrichment and oncomine expression analysis suggested that the transcription factor family E2F played an important role for the regulation of genes involve in cervical carcinogenesis. Our results suggest that E2F possesses diagnostic/prognostic value and can act as a potential drug target in cervical cancer.