CacyBP/SIP expression is involved in the clinical progression of breast cancer. World J Surg. 2010;34:2545-2552. [PMID: 20585948 DOI: 10.1007/s00268-010-0690-2]

Integrative bioinformatics and experimental analyses identify U2SURP as a novel lactylation-related prognostic signature in esophageal carcinoma

The lactylation modification has been implicated in several cancer types; however, the role of lactylation modification-related genes in esophageal carcinoma (EC) remains underexplored. Utilizing a set of 16 lactylation modification-related genes, cohorts of patients with EC were stratified into two distinct clusters, characterized by significant disparities in both survival outcomes and the immune microenvironment. An extensive bioinformatics analysis unveiled 382 differentially expressed genes (DEGs) between these two clusters. A subsequent univariate Cox regression analysis identified 24 DEGs specifically associated with lactylation, forming the basis of a constructed lactylation-related score. The resultant lactylation-related score exhibited notable predictive efficacy for survival and other clinicopathological traits, which was validated through calibration curves, Kaplan-Meier survival curves and the Wilcoxon test. Moreover, the lactylation-related score displayed a close correlation with immune cell infiltration in EC. Notable differential expressions of immune checkpoints and regulators were observed between groups stratified by low and high lactylation scores, with the latter exhibiting a more favorable response to anti-PD-1/PD-L1 therapy. Furthermore, the expression profile of U2 snRNP associated SURP domain containing (U2SURP), a constituent of the lactylation-related score, underwent both ex vivo and in vitro validation. The expression of U2SURP was significantly associated with lactylation levels, histological grade and tumor stage. Notably, knockdown of U2SURP expression inhibited the lactylation levels, immune genes IL-1A and IL-1B, proliferation, migration and invasion of EC cells. In conclusion, the lactylation-related score developed in the present study showed promise in predicting the prognosis and immunotherapeutic responses among patients with EC. Moreover, the identification of U2SUPR as a novel oncogene in EC suggests its potential as a prospective therapeutic target for EC treatment.

Evaluation of CacyBP/SIP expression and its relationship with ERK1/2 and p38 kinase in testicular seminoma

Testicular cancer accounts for approximately 5 % of all urologic cancers. The most common histopathological diagnosis of testicular neoplastic lesions are germ cell tumors (90-95 % of cases), among which the majority of cases are seminomas, the most common malignant tumors among men aged 15-44. For better clinical diagnosis and treatment, it is important to understand the molecular mechanisms of tumor formation. In this study, the expression of the CacyBP/SIP protein and ERK1/2 and p38 kinases was analyzed for the first time in seminomas and normal testicular tissues. The research was carried out using archival tissue material from 30 patients undergoing surgery due to testicular seminoma, whereas the comparative material consisted of the adjacent normal tissues. Immunohistochemistry and qRT-PCR were used to identify the expression of CacyBP/SIP, ERK1/2, and p38. A marked weakening of the immunohistochemical reaction was observed in the cancerous tissue compared to the control tissue. PCR testing of the marked proteins confirmed their lower expression in seminoma. Our findings suggest the involvement of the CacyBP/SIP protein in the ERK1/2 and p38 signalling pathways, which may be involved in the processes of testicular seminoma carcinogenesis. The results of our research provide the basis for further research in this area.

CacyBP promotes the development of lung adenocarcinoma by regulating OTUD5

Lung cancer is the most common and lethal malignancy, with lung adenocarcinoma accounting for approximately 40% of all cases. Despite some progress in understanding the pathogenesis of this disease and developing new therapeutic approaches, the current treatments for lung adenocarcinoma remain ineffective due to factors such as high tumour heterogeneity and drug resistance. Therefore, there is an urgent need to identify novel therapeutic targets. Calcyclin-binding protein (CacyBP) can regulate a variety of physiological processes by binding to different proteins, but its function in lung adenocarcinoma is unknown. Here, we show that CacyBP is highly expressed in lung adenocarcinoma tissues, and high CacyBP expression correlates with poorer patient survival. Moreover, overexpression of CacyBP promoted the proliferation, migration and invasion of lung adenocarcinoma cell lines. Further mechanistic studies revealed that CacyBP interacts with the tumour suppressor ovarian tumour (OTU) deubiquitinase 5 (OTUD5), enhances the ubiquitination and proteasomal degradation of OTUD5 and regulates tumourigenesis via OTUD5. In conclusion, our study reveals a novel mechanism by which CacyBP promotes tumourigenesis by increasing the ubiquitination level and proteasome-dependent degradation of OTUD5, providing a potential target for the treatment of lung adenocarcinoma.

The Novel-Natural-Killer-Cell-Related Gene Signature Predicts the Prognosis and Immune Status of Patients with Hepatocellular Carcinoma

The current understanding of the prognostic significance of natural killer (NK) cells and their tumor microenvironment (TME) in hepatocellular carcinoma (HCC) is limited. Thus, we screened for NK-cell-related genes by single-cell transcriptome data analysis and developed an NK-cell-related gene signature (NKRGS) using multi-regression analyses. Patients in the Cancer Genome Atlas cohort were stratified into high- and low-risk groups according to their median NKRGS risk scores. Overall survival between the risk groups was estimated using the Kaplan-Meier method, and a NKRGS-based nomogram was constructed. Immune infiltration profiles were compared between the risk groups. The NKRGS risk model suggests significantly worse prognoses in patients with high NKRGS risk (p < 0.05). The NKRGS-based nomogram showed good prognostic performance. The immune infiltration analysis revealed that the high-NKRGS-risk patients had significantly lower immune cell infiltration levels (p < 0.05) and were more likely to be in an immunosuppressive state. The enrichment analysis revealed that immune-related and tumor metabolism pathways highly correlated with the prognostic gene signature. In this study, a novel NKRGS was developed to stratify the prognosis of HCC patients. An immunosuppressive TME coincided with the high NKRGS risk among the HCC patients. The higher KLRB1 and DUSP10 expression levels correlated with the patients' favorable survival.

RAGE Inhibitors for Targeted Therapy of Cancer: A Comprehensive Review

The receptor for advanced glycation end products (RAGE) is a member of the immunoglobulin family that is overexpressed in several cancers. RAGE is highly expressed in the lung, and its expression increases proportionally at the site of inflammation. This receptor can bind a variety of ligands, including advanced glycation end products, high mobility group box 1, S100 proteins, adhesion molecules, complement components, advanced lipoxidation end products, lipopolysaccharides, and other molecules that mediate cellular responses related to acute and chronic inflammation. RAGE serves as an important node for the initiation and stimulation of cell stress and growth signaling mechanisms that promote carcinogenesis, tumor propagation, and metastatic potential. In this review, we discuss different aspects of RAGE and its prominent ligands implicated in cancer pathogenesis and describe current findings that provide insights into the significant role played by RAGE in cancer. Cancer development can be hindered by inhibiting the interaction of RAGE with its ligands, and this could provide an effective strategy for cancer treatment.

Protective effects of calcyclin-binding protein against pulmonary vascular remodeling in flow-associated pulmonary arterial hypertension

BACKGROUND

Pulmonary arterial hypertension associated with congenital heart disease (CHD-PAH) is recognized as a cancer-like disease with a proliferative and pro-migratory phenotype in pulmonary artery smooth muscle cells (PASMCs). Calcyclin-binding protein/Siah-1-interacting protein (CacyBP/SIP) has been implicated in the progression of various cancers; however, it has not been previously studied in the context of CHD-PAH. Here, we aimed to examine the function of CacyBP/SIP in CHD-PAH and explore its potential as a novel regulatory target for the disease.

METHODS

The expression of CacyBP/SIP in PASMCs was evaluated both in the pulmonary arterioles of patients with CHD-PAH and in high-flow-induced PAH rats. The effects of CacyBP/SIP on pulmonary vascular remodeling and PASMC phenotypic switch, proliferation, and migration were investigated. LY294002 (MedChemExpress, NJ, USA) was used to block the phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) pathway to explore changes in PASMC dysfunction induced by low CacyBP/SIP levels. Hemodynamics and pulmonary arterial remodeling were further explored in rats after short-interfering RNA-mediated decrease of CacyBP/SIP expression.

RESULTS

CacyBP/SIP expression was markedly reduced both in the remodeled pulmonary arterioles of patients with CHD-PAH and in high-flow-induced PAH rats. Low CacyBP/SIP expression promoted hPASMC phenotypic switch, proliferation, and migration via PI3K/AKT pathway activation. Our results indicated that CacyBP/SIP protected against pulmonary vascular remodeling through amelioration of hPASMC dysfunction in CHD-PAH. Moreover, after inhibition of CacyBP/SIP expression in vivo, we observed increased right ventricular hypertrophy index, poor hemodynamics, and severe vascular remodeling.

CONCLUSIONS

CacyBP/SIP regulates hPASMC dysfunction, and its increased expression may ameliorate progression of CHD-PAH.

Integrated In Silico Analyses Identify PUF60 and SF3A3 as New Spliceosome-Related Breast Cancer RNA-Binding Proteins

More women are diagnosed with breast cancer (BC) than any other type of cancer. Although large-scale efforts have completely redefined cancer, a cure remains unattainable. In that respect, new molecular functions of the cell should be investigated, such as post-transcriptional regulation. RNA-binding proteins (RBPs) are emerging as critical post-transcriptional modulators of tumorigenesis, but only a few have clear roles in BC. To recognize new putative breast cancer RNA-binding proteins, we performed integrated in silico analyses of all human RBPs (n = 1392) in three major cancer databases and identified five putative BC RBPs (PUF60, TFRC, KPNB1, NSF, and SF3A3), which showed robust oncogenic features related to their genomic alterations, immunohistochemical changes, high interconnectivity with cancer driver genes (CDGs), and tumor vulnerabilities. Interestingly, some of these RBPs have never been studied in BC, but their oncogenic functions have been described in other cancer types. Subsequent analyses revealed PUF60 and SF3A3 as central elements of a spliceosome-related cluster involving RBPs and CDGs. Further research should focus on the mechanisms by which these proteins could promote breast tumorigenesis, with the potential to reveal new therapeutic pathways along with novel drug-development strategies.

Downregulation of CacyBP by CRISPR/dCas9-KRAB Prevents Bladder Cancer Progression

Bladder cancer (BCa) is a leading cause of cancer-related death in the world. CacyBP is initially described as a binding partner of calcyclin and has been shown to be involved in a wide range of cellular processes, including cell differentiation, proliferation, protein ubiquitination, cytoskeletal dynamics and tumorigenesis. In the present study, we found that CacyBP expression was significantly upregulated in BCa tissues compared with adjacent normal tissues. Moreover, its expression was negatively correlated with overall survival time. Secondly, CacyBP had higher expressions in BCa cell lines than normal urothelial cells which was consistent with the results of BCa tissues. Finally, knockdown of CacyBP by CRIPSR-dCas9-KRAB in T24 and 5,637 BCa cells inhibited cell proliferation and migration by CCK-8 assay and scratch assay, and promoted apoptosis by caspase-3/ELISA. These data elucidate that CacyBP is an important oncogene contributing to malignant behavior of BCa and provide a potentially molecular target for treatment of BCa.

Discovery of Novel Protein Biomarkers in Urine for Diagnosis of Urothelial Cancer Using iTRAQ Proteomics

Urothelial carcinoma (UC) is the ninth most prevalent malignancy worldwide. Noninvasive and efficient biomarkers with high accuracy are imperative for the surveillance and diagnosis of UC. CKD patients were enrolled as a control group in this study for the discovery of highly specific urinary protein markers of UC. An iTRAQ-labeled quantitative proteomic approach was used to discover novel potential markers. These markers were further validated with 501 samples by ELISA assay, and their diagnostic accuracies were compared to those of other reported UC markers. BRDT, CYBP, GARS, and HDGF were identified as novel urinary UC biomarkers with a high discrimination ability in a population comprising CKD and healthy subjects. The diagnostic values of the four novel UC markers were better than that of a panel of well-known or FDA-approved urinary protein markers CYFR21.1, Midkine, and NUMA1. Three of our discovered markers (BRDT, HDGF, GARS) and one well-known marker (CYFR21.1) were finally selected and combined as a marker panel having AUC values of 0.962 (95% CI, 0.94-0.98) and 0.860 (95% CI, 0.83-0.89) for the discrimination between UC and normal groups and UC and control (healthy + CKD) groups, respectively.

Friend or Foe: S100 Proteins in Cancer

S100 proteins are widely expressed small molecular EF-hand calcium-binding proteins of vertebrates, which are involved in numerous cellular processes, such as Ca²⁺ homeostasis, proliferation, apoptosis, differentiation, and inflammation. Although the complex network of S100 signalling is by far not fully deciphered, several S100 family members could be linked to a variety of diseases, such as inflammatory disorders, neurological diseases, and also cancer. The research of the past decades revealed that S100 proteins play a crucial role in the development and progression of many cancer types, such as breast cancer, lung cancer, and melanoma. Hence, S100 family members have also been shown to be promising diagnostic markers and possible novel targets for therapy. However, the current knowledge of S100 proteins is limited and more attention to this unique group of proteins is needed. Therefore, this review article summarises S100 proteins and their relation in different cancer types, while also providing an overview of novel therapeutic strategies for targeting S100 proteins for cancer treatment.

CACYBP Enhances Cytoplasmic Retention of P27Kip1 to Promote Hepatocellular Carcinoma Progression in the Absence of RNF41 Mediated Degradation

Calcyclin-binding protein (CACYBP) is a multi-ligand protein implicated in the progression of various human cancers. However, its function in hepatocellular carcinoma (HCC) remains unknown.

Methods: The expression of CACYBP and RNF41 (RING finger protein 41) in HCC cancer and adjacent non-tumor tissues was detected by immunohistochemistry. CCK-8 assays, colony formation assays, flow cytometry detection and xenograft models were used to evaluate the impact of CACYBP expression on HCC cell growth, apoptosis and cell cycle regulation. Immunoprecipitation and ubiquitination assays were performed to determine how RNF41 regulates CACYBP. The regulatory mechanism of RNF41-CACYBP signaling axis on P27^Kip1 was investigated by western blotting and immunofluorescence.

Results: CACYBP was highly expressed and associated with poor prognosis in HCC. CACYBP expression was required for HCC cell growth in vitro and in vivo. Moreover, we identified RNF41 as a specific binding partner of CACYBP at exogenous and endogenous levels. RNF41 recruited CACYBP by its C-terminal substrate binding domain, subsequently ubiquitinating CACYBP and promoting its degradation in both proteasome- and lysosome-dependent pathways. In HCC tissues, RNF41 expression was reduced and conferred a negative correlation with CACYBP expression. Mechanistically, CACYBP overexpression stimulated the Ser10, Thr157 and Thr198 phosphorylation of P27^Kip1 and its cytoplasmic retention, and RNF41 co-expression attenuated this phenomenon. CACYBP depletion led to decreased levels of cyclin D1, cyclin A2, CDK2 and CDK4, causing a typical cell cycle arrest at G1/S phase and increasing apoptosis in HCC cells. P27^Kip1-S10D but not P27^Kip1-S10A reconstitution rescued partially the cell cycle function and apoptotic feature after CACYBP depletion.

Conclusion: Our findings provide novel insights into the functional role and regulatory mechanism of CACYBP in HCC.

CacyBP/SIP inhibits the migration and invasion behaviors of glioblastoma cells through activating Siah1 mediated ubiquitination and degradation of cytoplasmic p27

Calcyclin-binding protein or Siah-1-interacting protein (CacyBP/SIP) has been reported to be up-regulated and plays an important role in promoting cell proliferation in human glioma. However, the effect of CacyBP/SIP on glioma cell motility is still unclear. Here, to our surprise, CacyBP/SIP was found to inhibit the migration and invasion of glioma cells U251 and U87. Silencing of CacyBP/SIP significantly promoted the migration and invasion behaviors of glioma cells. On the contrary, overexpression of CacyBP/SIP obviously suppressed them. Further investigation indicated that silencing of CacyBP/SIP significantly reduced the interaction between Siah1 and cytoplasmic p27, which in turn attenuated the ubiquitination and degradation of cytoplasmic p27. In contrast, overexpression of CacyBP/SIP promoted the interaction between Siah1 and cytoplasmic p27, which in turn increased the ubiquitination and degradation of cytoplasmic p27. Importantly, the degradation of p27 could be blocked by Siah1 knockdown. Finally, we found that CacyBP/SIP was reversely related to cytoplasmic p27 in human normal brain tissues and glioma tissues. Taken together, these results suggest that CacyBP/SIP plays an important role in inhibiting glioma cell migration and invasion through promoting the degradation of cytoplasmic p27.

Cell cycle-dependent translocation and regulatory mechanism of CacyBP/SIP in gastric cancer cells

Our previous results showed that calcyclin-binding protein/Siah-1-interacting protein (CacyBP/SIP) inhibits the proliferation and tumorigenicity of gastric cancer; however, the exact mechanism remains unclear, especially from the aspect of cell cycle. The subcellular localization of CacyBP/SIP, Siah-1, and Skp1 in SGC7901 gastric cancer cells was assessed by immunofluorescence after cell cycle synchronization. Levels of CacyBP/SIP, Siah-1, Skp1, β-catenin, and p-ERK1/2 were analyzed by western blotting. CacyBP/SIP phosphorylation (p-CacyBP/SIP) and the combining capacity of Siah-1 and Skp1 with CacyBP/SIP in nucleoprotein were determined by immunoprecipitation. CacyBP/SIP, Siah-1, and Skp1 were mainly in the cytoplasm in the G1 phase, but translocated to the nucleus during G2. Their expression in total protein was not altered, but elevated in the G2 phase in nucleoprotein. The CacyBP/SIP nucleus translocation of cells transfected with mutant CacyBP/SIP that does not bind S100 (CacyBP-ΔS100) was significantly increased compared with wild-type CacyBP/SIP. In the G2 phase, p-CacyBP/SIP expression and the combining capacity of Siah-1 and Skp1 with CacyBP/SIP were all increased, whereas levels of β-catenin and p-ERK1/2 reduced, compared with the G1 phase. CacyBP/SIP or CacyBP-ΔS100 overexpression was correlated with constitutively low β-catenin expression and affected its level through cell cycle. CacyBP/SIP overexpression led to retarded proliferation, G1 arrest, and β-catenin reduction, which could be abolished by lithium chloride, β-catenin activator, and further enhanced by the Wnt inhibitor XAV-939. In addition, CacyBP-ΔS100 further suppressed cell proliferation and induced G1 arrest compared with CacyBP/SIP. In conclusion, CacyBP/SIP nuclear localization, dependent on S100 protein, suppresses gastric cancer tumorigenesis through β-catenin degradation and the dephosphorylation of ERK1/2 during the G2 phase.

CacyBP/SIP nuclear translocation regulates p27Kip1 stability in gastric cancer cells

AIM: To investigate the mechanism of calcyclin binding protein/Siah-1 interacting protein (CacyBP/SIP) nuclear translocation in promoting the proliferation of gastric cancer (GC) cells.

METHODS: The effect of CacyBP/SIP nuclear translocation on cell cycle was investigated by cell cycle analysis. Western blot analysis was used to assess the change in expression of cell cycle regulatory proteins and proteasome-mediated degradation of p27Kip1. Co-immunoprecipitation (co-IP) analysis was performed to examine the binding of CacyBP/SIP with Skp1. A CacyBP/SIP truncation mutant which lacked the Skp1 binding site was constructed and fused to a fluorescent protein. Subsequently, the effect on Skp1 binding with the fusion protein was examined by co-IP, while localization of fluorescent fusion protein observed by confocal laser microscopy, and change in p27Kip1 protein expression assessed by Western blot analysis.

RESULTS: CacyBP/SIP nuclear translocation induced by gastrin promoted progression of GC cells from G1 phase. However, while CacyBP/SIP nuclear translocation was inhibited using siRNA to suppress CacyBP/SIP expression, cell cycle was clearly inhibited. CacyBP/SIP nuclear translocation significantly decreased the level of cell cycle inhibitor p27Kip1, increased Cyclin E protein expression whereas the levels of Skp1, Skp2, and CDK2 were not affected. Upon inhibition of CacyBP/SIP nuclear translocation, there were no changes in protein levels of p27Kip1 and Cyclin E, while p27Kip1 decrease could be prevented by the proteasome inhibitor MG132. Moreover, CacyBP/SIP was found to bind to Skp1 by immunoprecipitation, an event that was abolished by mutant CacyBP/SIP, which also failed to stimulate p27Kip1 degradation, even though the mutant could still translocate into the nucleus.

CONCLUSION: CacyBP/SIP nuclear translocation contributes to the proliferation of GC cells, and CacyBP/SIP exerts this effect, at least in part, by stimulating ubiquitin-mediated degradation of p27Kip1.

The potential role of CacyBP/SIP in tumorigenesis

Calcyclin-binding protein/Siah-1-interacting protein (CacyBP/SIP) was initially described as a binding partner of S100A6 in the Ehrlich ascites tumor cells and later as a Siah-1-interacting protein. This 30 kDa protein includes three domains and is involved in cell proliferation, differentiation, cytoskeletal rearrangement, and transcriptional regulation via binding to various proteins. Studies have also shown that the CacyBP/SIP is a critical protein in tumorigenesis. But, its promotion or suppression of cancer progression may depend on the cell type. In this review, the biological characteristics and target proteins of CacyBP/SIP have been described. Moreover, the exact role of CacyBP/SIP in various cancers is discussed.

CacyBP/SIP inhibits Doxourbicin-induced apoptosis of glioma cells due to activation of ERK1/2

Calcyclin-binding protein or Siah-1-interacting protein (CacyBP/SIP) was previously reported to promote the proliferation of glioma cells. However, the effect of CacyBP/SIP on apoptosis of glioma is poorly understood. Here, our study shows that CacyBP/SIP plays a role in inhibiting doxorubicin (DOX) induced apoptosis of glioma cells U251 and U87. Overexpression of CacyBP/SIP obviously suppressed the DOX-induced cell apoptosis. On the contrary, silencing of CacyBP/SIP significantly promoted it. Further investigation indicated that inhibition of apoptosis by CacyBP/SIP was relevant to its nuclear translocation in response to the DOX treatment. Importantly, we found that the level of p-ERK1/2 in nuclei was related to the nuclear accumulation of CacyBP/SIP. Finally, the role of CacyBP/SIP was confirmed in vivo in a mouse model with the cell line stably silencing CacyBP/SIP. Taken together, our results suggest that CacyBP/SIP plays an important role in inhibiting apoptosis of glioma cells which might be mediated by ERK1/2 signaling pathway, which will provide some guidance for the treatment of glioma.

Down-regulation of miR-320 associated with cancer progression and cell apoptosis via targeting Mcl-1 in cervical cancer

Our previous studies have demonstrated overexpression of Mcl-1 in cervical cancer tumorigenesis. However, the molecular mechanism of its overexpression remains not elucidated. MiR-320 has been reported to be down-regulated in various types of cancer, and bioinformatics prediction indicated that it may regulate the expression of Mcl-1. The aim of this study is to investigate the role of miR-320 and its target gene Mcl-1 in cervical cancer progression and to assess their clinical significance. miR-320 and Mcl-1 expressions in human cervical cancer tissues were investigated by qRT-PCR, in situ hybridization, and immunohistochemical staining, respectively. The clinicopathological implications of these molecules were analyzed. Bioinformatic prediction and luciferase assays were employed to identify the predicted microRNA (miRNA) which regulates Mcl-1. The apoptosis, proliferation, migration, and invasion assays were performed to investigate the effect of miR-320 on the cervical cancer cells. MiR-320 expression is significantly down-regulated versus Mcl-1 expression is up-regulated in cervical cancer tissues compared with normal controls with a negative correlation between them. Luciferase assay showed that miR-320 negatively regulates Mcl-1 expression. In addition, miR-320 induces apoptosis via down-regulation of Mcl-1 and activation of caspase-3 but inhibits cell proliferation, migration, invasion, and tumorigenesis in cervical cancer cells. Our studies show that miR-320 expression is decreased in cervical cancer, and its expression is negatively correlated with Mcl-1 expression in cervical cancer. In addition, miR-320 inhibits cervical cancer progression by down-regulation of Mcl-1. These results indicate that miR-320 may be an important biomarker and target for diagnosis and treatment of cervical cancer patient.

CacyBP/SIP--Structure and variety of functions

BACKGROUND

CacyBP/SIP (Calcyclin-Binding Protein and Siah-1 Interacting Protein) is a small modular protein implicated in a wide range of cellular processes. It is expressed in different tissues of mammals but homologs are also found in some lower organisms. In mammals, a high level of CacyBP/SIP is present in tumor cells and in neurons. CacyBP/SIP binds several target proteins such as members of the S100 family, components of a ubiquitin ligase complex, and cytoskeletal proteins.

SCOPE OF REVIEW

CacyBP/SIP has been shown to be involved in protein de-phosphorylation, ubiquitination, cytoskeletal dynamics, regulation of gene expression, cell proliferation, differentiation, and tumorigenesis. This review focuses on very recent reports on CacyBP/SIP structure and function in these important cellular processes.

MAJOR CONCLUSIONS

CacyBP/SIP is a multi-domain and multi-functional protein. Altered levels of CacyBP/SIP in several cancers implicate its involvement in the maintenance of cell homeostasis. Changes in CacyBP/SIP subcellular localization in neurons of AD brains suggest that this protein is strongly linked to neurodegenerative diseases. Elucidation of CacyBP/SIP structure and cellular function is leading to greater understanding of its role in normal physiology and disease pathologies.

GENERAL SIGNIFICANCE

The available results suggest that CacyBP/SIP is a key player in multiple biological processes. Detailed characterization of the physical, biochemical and biological properties of CacyBP/SIP will provide better insight into the regulation of its diverse functions in vivo, and given the association with specific diseases, will help clarify the potential of therapeutic targeting of this protein.

Role of the CacyBP/SIP protein in gastric cancer

Various reports indicate that calcyclin binding protein/Siah-1-interacting protein (CacyBP/SIP) is an important protein in tumorigenesis, but whether CacyBP/SIP promotes or suppresses cancer may depend on the cell type. In order to investigate whether CacyBP/SIP is significant in gastric cancerous tumorigenesis, the present study used immunohistochemistry to analyze 181 gastric cancer tissue samples, as well as 181 healthy tissue samples from the same gastric cancer patients. The immunohistochemical results were compared against patient data and pathological analysis of the tissue slices, including gender, age, degree of tumor differentiation and tumor, node, metastasis (TNM) stage. In addition, the level of CacyBP/SIP expression was detected in three frozen tissue samples of gastric adenocarcinoma using western blot analysis. Of the 181 cases analyzed in the present study, 80 cases were identified as non-metastatic gastric cancer and 101 cases were identified as gastric cancer that had metastasized to the lymph nodes. Tissue biopsies from the two sets of patients were examined using immunohistochemistry to identify the level of CacyBP/SIP expression in metastatic and primary gastric cancer tissues. Statistical analyses were performed on all data. The immunohistochemical analysis revealed that CacyBP/SIP was expressed in 31% (56/181) of gastric adenocarcinoma tissue samples and 7% (12/181) of adjacent non-cancerous gastric tissues (P<0.05). Furthermore, the expression levels of CacyBP/SIP were higher in cancerous tissue compared with the adjacent non-cancerous gastric tissue using western blotting. No association was identified between CacyBP/SIP expression and patient age (P=0.975), gender (P=0.185), degree of tumor differentiation (P=0.076) or TNM stage (P=0.979). Among the 101 patients with metastatic gastric cancer, CacyBP/SIP was expressed at primary sites in 31% (31/101) of cases and at metastatic sites in 26% (26/101) of cases (P=0.434). However, among the 80 patients with non-metastatic gastric cancer, CacyBP/SIP was expressed at the tumor site in 34% (27/80) of cases, which was not significantly different from the 31% (25/80) of cases in the metastatic group (P=0.662). These findings indicate that CacyBP/SIP expression is not a marker of gastric cancer or metastatic gastric cancer, nor does it appear to correlate with the clinicopathological features of gastric cancer.

CacyBP/SIP nuclear translocation induced by gastrin promotes gastric cancer cell proliferation

AIM: To investigate the role of nuclear translocation of calcyclin binding protein, also called Siah-1 interacting protein (CacyBP/SIP), in gastric carcinogenesis.

METHODS: The expression of CacyBP/SIP protein in gastric cancer cell lines was detected by Western blot. Immunofluorescence experiments were performed on gastric cancer cell lines that had been either unstimulated or stimulated with gastrin. To confirm the immunofluorescence findings, the relative abundance of CacyBP/SIP in nuclear and cytoplasmic compartments was assessed by Western blot. The effect of nuclear translocation of CacyBP/SIP on cell proliferation was examined using MTT assay. The colony formation assay was used to measure clonogenic cell survival. The effect of CacyBP/SIP nuclear translocation on cell cycle progression was investigated. Two CacyBP/SIP-specific siRNA vectors were designed and constructed to inhibit CacyBP/SIP expression in order to reduce the nuclear translocation of CacyBP/SIP, and the expression of CacyBP/SIP in stably transfected cells was determined by Western blot. The effect of inhibiting CacyBP/SIP nuclear translocation on cell proliferation was then assessed.

RESULTS: CacyBP/SIP protein was present in most of gastric cancer cell lines. In unstimulated cells, CacyBP/SIP was distributed throughout the cytoplasm; while in stimulated cells, CacyBP/SIP was found mainly in the perinuclear region. CacyBP/SIP nuclear translocation generated a growth-stimulatory effect on cells. The number of colonies in the CacyBP/SIP nuclear translocation group was significantly higher than that in the control group. The percentage of stimulated cells in G1 phase was significantly lower than that of control cells (69.70% ± 0.46% and 65.80% ± 0.60%, control cells and gastrin-treated SGC7901 cells, P = 0.008; 72.99% ± 0.46% and 69.36% ± 0.51%, control cells and gastrin-treated MKN45 cells, P = 0.022). CacyBP/SIPsi1 effectively down-regulated the expression of CacyBP/SIP, and cells stably transfected by CacyBP/SIPsi1 were then chosen for further cellular assays. In CacyBP/SIPsi1 stably transfected cells, CacyBP/SIP was shown to be distributed throughout the cytoplasm, irregardless of whether they were stimulated or not. After CacyBP/SIP nuclear translocation was reduced, there had no major effect on cell proliferation, as shown by MTT assay. There had no enhanced anchorage-dependent growth upon stimulation, as indicated by colony formation in flat plates. No changes appeared in the percentage of cells in G0-G1 phase in either cell line (71.09% ± 0.16% and 70.86% ± 0.25%, control cells and gastrin-treated SGC7901-CacyBP/SIPsi1 cells, P = 0.101; 74.17% ± 1.04% and 73.07% ± 1.00%, control cells and gastrin-treated MKN45-CacyBP/SIPsi1 cells, P = 0.225).

CONCLUSION: CacyBP/SIP nuclear translocation promotes the proliferation and cell cycle progression of gastric cancer cells.

Clinical significance of expression of CacyBP/SIP in colorectal tissues

AIM: To detect the expression of CacyBP/SIP [Calcyclin (S100A6)-binding protein/Siah-1 interacting protein] in normal colorectal tissue, colorectal hyperplastic polyps, colorectal adenoma and colorectal cancer.

METHODS: Immunohistochemistry was used to analyze the expression of CacyBP/SIP in 10 normal colorectal tissue samples, 17 samples of colorectal hyperplastic polyps, 26 samples of colorectal adenomas and 50 samples of colorectal cancer. Four frozen tissue samples of colorectal cancer and adjacent noncancerous tissues were used in Western blot to detect CacyBP/SIP expression. Immunohistochemical results were compared against patient data and pathological analysis of tissue slices. Slices were assessed for associations with gender, age, degree of tumor differentiation and TNM stage.

RESULTS: CacyBP/SIP was detected in 0 (0/10) of normal tissue samples, 17.7% (7/26) of colorectal hyperplastic polyps, 26.9% (7/26) of colorectal adenomas, and 52% (26/50) of colorectal cancer tissues by immunohistochemistry. The expression of CacyBP/SIP in colorectal adenomas and colorectal cancer tissues was higher than that in the normal colon tissue and colorectal hyperplasic polyps (0 vs 26.9%, 0 vs 52%, 17.7% vs 26.9%, 17.7% vs 52%, P < 0.05 for all). The expression of CacyBP/SIP was also higher in cancerous tissue than in adjacent noncancerous colorectal tissue, as revealed by Western blot (P < 0.05). There was no association between CacyBP/SIP expression and patient age, gender, degree of tumor differentiation or TNM stage (P > 0.05 for all).

CONCLUSION: These results suggest that CacyBP/SIP may be involved in the progression of colorectal cancer.

iTRAQ based quantitative proteomics approach validated the role of calcyclin binding protein (CacyBP) in promoting colorectal cancer metastasis

Keeping continuity with our previous study that revealed direct correlations between CRC metastasis and enhanced CacyBP protein levels, here we attempt to improve our understanding of the mechanisms involved within this enigmatic process. Overexpression of CacyBP (CacyBP-OE) in primary CRC cell and its knock down (CacyBP-KD) in the metastatic CRC cells revealed (through phenotypic studies) the positive impact of the protein on metastasis. Additionally, two individual 4-plex iTRAQ based comparative proteomics experiments were carried out on the CacyBP-OE and CacyBP-KD cells, each with two biological replicates. Mining of proteomics data identified total 279 (63.80% up-regulated and 36.20% down-regulated) proteins to be significantly altered in expression level for the OE set and in the KD set, this number was 328 (48.78% up-regulated and 51.22% down-regulated). Functional implications of these significantly regulated proteins were related to metastatic phenotypes such as cell migration, invasion, adhesion and proliferation. Gene ontology analysis identified integrin signaling as the topmost network regulated within CacyBP-OE. Further detection of caveolar mediated endocytosis in the top hit list correlated this phenomenon with the dissociation of integrins from the focal adhesion complex which are known to provide the traction force for cell movement when transported back to the leading edge. This finding was further supported by the data obtained from CacyBP-KD data set showing down-regulation of proteins necessary for integrin endocytosis. Furthermore, intracellular calcium levels (known to influence integrin mediated cell migration) were found to be lowered in CacyBP-KD cells indicating decreased cell motility and vice versa for the CacyBP-OE cells. Actin nucleation by ARP-WASP complex, known to promote cell migration, was also identified as one of the top regulated pathways in CacyBP-OE cells. In short, this study presents CacyBP as a promising candidate biomarker for CRC metastasis and also sheds light on the underlying molecular mechanism by which CacyBP promotes CRC metastasis.

Tissue biomarkers of breast cancer and their association with conventional pathologic features

Background:

Tissue protein expression profiling has the potential to detect new biomarkers to improve breast cancer (BC) diagnosis, staging, and prognostication. This study aimed to identify tissue proteins that differentiate breast cancer tissue from healthy breast tissue using protein chip mass spectrometry and to examine associations with conventional pathological features.

Methods:

To develop a training model, 82 BC and 82 adjacent unaffected tissue (AT) samples were analysed on cation-exchange protein chips by time-of-flight mass spectrometry. For validation, 89 independent BC and AT sample pairs were analysed.

Results:

From the protein peaks that were differentially expressed between BC and AT by univariate analysis, binary logistic regression yielded two peaks that together classified BC and AT with a ROC area under the curve of 0.92. Two proteins, ubiquitin and S100P (in a novel truncated form), were identified by liquid chromatography/tandem mass spectrometry and validated by immunoblotting and reactive-surface protein chip immunocapture. The combined marker panel was positively associated with high histologic grade, larger tumour size, lymphovascular invasion, ER and PR positivity, and HER2 overexpression, suggesting that it may be associated with a HER2-enriched molecular subtype of breast cancer.

Conclusion:

This independently validated protein panel may be valuable in the classification and prognostication of breast cancer patients.

Up-regulation of CacyBP/SIP during rat breast cancer development

Background

CacyBP/SIP (calcyclin binding protein/Siah-1 interacting protein) was originally discovered in Ehrlich ascities tumor cells but was later found also in many different tumors.

Methods

To better understand the function of CacyBP/SIP in carcinogenesis, we used immunohistochemistry, Western blotting, and RT-PCR assays to study the distribution and level of CacyBP/SIP in mammary tissues after tumor induction in rat with DMBA [(dimethylbenz[a]anthracene)]. Application of such a model allowed us to monitor changes in CacyBP/SIP level during development of breast cancer.

Results

We found that both the protein and mRNA levels of CacyBP/SIP gradually increased in pathologically changed tissues and were highest in tumors taken 8 weeks after DMBA treatment. Similar changes as for CacyBP/SIP were detected in the level of β-catenin.

Conclusion

Increase in CacyBP/SIP expression during development of breast cancer, observed early in the mammary tissues with only minimal pathological changes, might suggest an important role of this protein in the process of carcinogenesis.

CacyBP/SIP phosphatase activity in neuroblastoma NB2a and colon cancer HCT116 cells

Recently, we have reported that CacyBP/SIP could be a novel phosphatase for ERK1/2 kinase. In this work, we analyzed the CacyBP/SIP phosphatase activity toward ERK1/2 in 2 cell lines of different origin. We showed that overexpression of CacyBP/SIP in NB2a cells resulted in a lower level of phosphorylated ERK1/2 (P-ERK1/2) in the nuclear fraction while such overexpression in HCT116 cells had no effect on the level of P-ERK1/2. Moreover, we found that overexpression of CacyBP/SIP resulted in higher phosphatase activity in the nuclear fraction obtained from NB2a cells when compared with HCT116 cells. Using 2-D electrophoresis we showed that the pattern of spots representing CacyBP/SIP differed in these 2 cell lines and was probably due to a different phosphorylation state of this protein. We also established that after overexpression of CacyBP/SIP in NB2a cells, the amount of nuclear β-catenin was low, while it remained high in HCT116 cells. Since NB2a cells have differentiation potential and HCT116 cells do not, our data suggest that different activity of CacyBP/SIP in these 2 cell lines might affect the ERK1/2 pathway in the differentiation or proliferation processes.

Shortening of 3'UTRs correlates with poor prognosis in breast and lung cancer

A major part of the post-transcriptional regulation of gene expression is affected by trans-acting elements, such as microRNAs, binding the 3' untraslated region (UTR) of their target mRNAs. Proliferating cells partly escape this type of negative regulation by expressing shorter 3' UTRs, depleted of microRNA binding sites, compared to non-proliferating cells. Using large-scale gene expression datasets, we show that a similar phenomenon takes place in breast and lung cancer: tumors expressing shorter 3' UTRs tend to be more aggressive and to result in shorter patient survival. Moreover, we show that a gene expression signature based only on the expression ratio of alternative 3' UTRs is a strong predictor of survival in both tumors. Genes undergoing 3'UTR shortening in aggressive tumors of the two tissues significantly overlap, and several of them are known to be involved in tumor progression. However the pattern of 3' UTR shortening in aggressive tumors in vivo is clearly distinct from analogous patterns involved in proliferation and transformation.

Increased expression of fibroblastic growth factor receptor 2 is correlated with poor prognosis in patients with breast cancer

BACKGROUND AND OBJECTIVES

Although there is growing evidence supporting the hypothesis that fibroblast growth factor receptor 2 (FGFR2) is one of the few candidate genes linked with breast cancer susceptibility, the precise role of FGFR2 protein expression in breast cancer is still unknown. Our study examines FGFR2 protein expression in breast cancer and determines its associations with clinicopathological features and survival.

METHODS

Specimens from 125 invasive ductal carcinoma grade 2 (IDC2) breast cancer patients were investigated by immunohistochemistry for FGFR2 protein expression. Associations between the expression of FGFR2 and various clinicopathological features as well as survival status were studied.

RESULT

Cytoplasmic and nuclear FGFR2 were expressed in 64.8% and 56.8% of breast cancer patients, respectively. Cytoplasmic FGFR2 expression was significantly associated with tumor size and TNM stage. Furthermore, patients with high expression levels of cytoplasmic and nuclear FGFR2 showed much lower overall survival (OS) and disease-free survival (DFS) rates than those patients with low FGFR2 expression. Cytoplasmic FGFR2 expression and lymph node metastasis were independent prognostic factors for both DFS and OS by multivariate analysis.

CONCLUSIONS

High FGFR2 expression is correlated with poor OS and DFS in breast cancer patients. It could be a biomarker for poor prognosis.

Relationship between CacyBP/SIP expression and prognosis in astrocytoma

The aim of this study was to investigate the expression of calcyclin-binding protein (also known as Siah-1-interacting protein [CacyBP/SIP]) in astrocytoma and to determine its prognostic value in overall survival of patients with glioblastoma multiforme (GBM). Tissue specimens were obtained from 77 Chinese patients who had undergone surgery for astrocytoma. The expression of CacyBP/SIP was examined by immunohistochemistry. The relationship between CacyBP/SIP and proliferating cell nuclear antigen index (PCNA) expression was investigated, and the prognostic value of CacyBP/SIP expression in patients with astrocytomas was analyzed. Of 77 tumors, 49 (63.6%) were negative for CacyBP/SIP expression. Loss of CacyBP/SIP expression was significantly associated with a high histological grade and with poor survival in univariate and multivariate analyses. Cox multivariable analysis showed that loss of CacyBP/SIP expression correlated with poor prognosis in patients with astrocytomas and was an independent prognostic factor (p<0.05). The mean survival time of patients with tumors that had lost expression of CacyBP/SIP was 25.58months (95% confidence interval [CI], 15.36-25.81months), compared to a mean survival time of 36.37months (95% CI, 27.90-44.84months) for patients with CacyBP/SIP-expressing tumors. CacyBP/SIP expression was also negatively correlated with PCNA expression in astrocytoma tissue (p<0.05). Our findings suggest that CacyBP/SIP may have an important role as a negative regulator of astrocytoma development and progression, and that CacyBP/SIP might be a useful molecular marker for predicting the prognosis of astrocytoma.