The prognostic significance of nuclear CSE1L in urinary bladder urothelial carcinomas

DDX27 regulates oral squamous cell carcinoma development through targeting CSE1L

THE HEADINGS AIMS

DEAD-box helicase 27 (DDX27), a member of the DEAD-Box nucleic acid helicase family, holds an elusive role in oral squamous cell carcinoma (OSCC). This study aims to unravel the regulatory functions of DDX27 in OSCC and explore its downstream targets.

MATERIALS AND METHODS

A commercial oral squamous cell carcinoma (OSCC) tissue microarray (TMA) was utilized. We analyzed differentially expressed genes in OSCC through the GEO database. Target gene silencing was achieved using the shRNA-mediated lentivirus method. Coexpedia analysis identified co-expressed genes associated with DDX27. Additionally, a Co-Immunoprecipitation (Co-IP) experiment confirmed the protein interaction between DDX27 and CSE1L. Xenograft tumor models were employed to evaluate DDX27's role in OSCC tumor formation.

KEY FINDINGS

Elevated DDX27 expression in OSCC correlated with a higher pathological grade. DDX27 knockdown resulted in decreased cell proliferation, increased apoptosis, inhibited cell migration, and induced G2/M phase cell cycle arrest, as well as impaired tumor outgrowth. Coexpedia analysis identified STAU1, NELFCD, and CSE1L as top co-expressed genes. Lentiviral vectors targeting STAU1, NELFCD, and CSE1L revealed that silencing CSE1L significantly impaired cell growth, indicating it as a downstream target of DDX27. Cell rescue experiments demonstrated that increased DDX27 levels ameliorated cell proliferation, attenuated apoptosis, and CSE1L depletion blocked cell development induced by DDX27 overexpression.

SIGNIFICANCES

This study highlighted DDX27 as a potential therapeutic target for OSCC treatment, shedding light on its crucial role in OSCC development. Targeting DDX27 or its downstream effector, CSE1L, holds promise for innovative OSCC therapies.

The role of CSE1L silencing in the regulation of proliferation and apoptosis via the AMPK/mTOR signaling pathway in chronic myeloid leukemia

OBJECTIVES

Chromosome segregation 1-like (CSE1L) is abundant and strongly expressed in solid tumors. However, the expression and role of CSE1L in chronic myeloid leukemia(CML) remain largely unknown.

MATERIALS AND METHODS

The relative expression levels of CSE1L in bone marrow granulocytes from patients with primary CML and non-hematologic controls were measured by flow cytometry. Cell counting kit-8 analysis, DNA Content Quantitation Assay, and Annexin V-PE/7-AAD staining were applied to assess the effects of CSE1L knockdown on cell proliferation, cell cycle progression, and apoptosis.

RESULTS

Elevated expression of CSE1L was detected in bone marrow granulocytes of patients with primary CML. In the CML cell line K562 cells, CSE1L knockdown impaired cell proliferation blocked the cell cycle shift from G0/G1 phase to the S phase, and promoted apoptosis. Knockdown of CSE1L reduced Bcl-2 protein expression and increased Bax protein expression. Meanwhile, knockdown of CSE1L enhanced the expression of phospho-AMPK protein and decreased the expression of phospho-mTOR protein. The expression of total AMPK and mTOR proteins was not affected. In addition, CSE1L expression levels were decreased in imatinib-treated K562 cells.

CONCLUSIONS

CSE1L plays a pivotal role in K562 cell survival and growth. These functions may be partially dependent on the AMPK/mTOR signaling pathway to achieve. In addition, CSE1L may have had a future impact on the treatment of CML patients.

Prognosis Risk Model Based on Necroptosis-Related Signature for Bladder Cancer

Background: Bladder cancer(BLCA) is the ninth most common cancer. In recent years, necroptosis was found to be related to the occurrence and development of tumors. In this study, we aimed to construct a model based on a necroptosis-related signature to evaluate the potential prognostic application in BLCA. Methods: A total of 67 necroptosis-related genes were used to select the ideal cluster numbers, and it was found that there were four necroptosis-related patterns. Then, we compared the gene expression levels among all of the groups and established a necroptosis-related prognostic model. We made the following enrichment analysis of function and built a novel scoring system, the NEC score, to evaluate the state of necroptosis according to the expression level of necroptosis-related genes. Results: A total of 67 necroptosis-related genes were used to define four distinct necroptosis-related patterns: NEC cluster1–4. Each NEC cluster exhibited different patterns of survival and immune infiltration. Based on univariate Cox regression analyses and least absolute shrinkage and selection operator (Lasso) regression, 14 necroptosis-related genes were established to develop the NEC score. Patients were divided into two groups based on the NEC score. Patients in the high NEC score group had a significantly poorer overall survival than those in the low NEC score group. We further confirmed the correlation of clinical characteristics, as well as the immunotherapy outcome, with the NEC score, and confirmed the potential of the NEC score to be an independent prognostic factor. Furthermore, we compared the expression levels of eight potential biomarker genes between our own BLCA tissues and para-carcinoma tissue. Conclusion: We developed a novel NEC score that has a potential prognostic value in BLCA patients and may help personalized immunotherapy counselling.

Role of CSE1L expression in determining recurrence and survival of laryngeal tumors

PURPOSE

The correlation of CSE1L (human chromosomal segregation 1-like) staining intensity with disease-free survival, disease recurrence and development of distant metastases in Advanced Laryngeal Tumors.

METHODS

Specimens of patients with advanced glottic larynx cancer (T3, T4) were evaluated for nuclear CSE1L staining intensity. According to mild, moderate and severe CSE1L staining, patients were compared in terms of disease-free survival, disease recurrence and development of distant metastases.

RESULTS

17 of the 57 patients died within 5 years, distant metastases developed in 5 patients, and recurrence in 5 patients. Of the 17 patients who died within 5 years, 10(%59) showed severe staining with CSE1L, 6 (%35) showed moderate staining, and only 1 (%6) patient showed mild staining. 4 (%80) out of 5 patients who developed distant metastases were those with moderate staining with CSE1L. Metastases did not develop in any patient who stained poorly with CSE1L. 2 (%40) of the 5 patients who developed relapse were patients with severe staining with CSE1L, while 3 (%60) were patients with moderate staining with CSE1L. No recurrence was observed in any patient with mild staining with CSE1L.

CONCLUSION

CSE1L will help in demonstrating the increased risk of distant metastasis, increased recurrence probability and shortened life expectancy of advanced laryngeal carcinoma.

PHY34 inhibits autophagy through V-ATPase V0A2 subunit inhibition and CAS/CSE1L nuclear cargo trafficking in high grade serous ovarian cancer

PHY34 is a synthetic small molecule, inspired by a compound naturally occurring in tropical plants of the Phyllanthus genus. PHY34 was developed to have potent in vitro and in vivo anticancer activity against high grade serous ovarian cancer (HGSOC) cells. Mechanistically, PHY34 induced apoptosis in ovarian cancer cells by late-stage autophagy inhibition. Furthermore, PHY34 significantly reduced tumor burden in a xenograft model of ovarian cancer. In order to identify its molecular target/s, we undertook an unbiased approach utilizing mass spectrometry-based chemoproteomics. Protein targets from the nucleocytoplasmic transport pathway were identified from the pulldown assay with the cellular apoptosis susceptibility (CAS) protein, also known as CSE1L, representing a likely candidate protein. A tumor microarray confirmed data from mRNA expression data in public databases that CAS expression was elevated in HGSOC and correlated with worse clinical outcomes. Overexpression of CAS reduced PHY34 induced apoptosis in ovarian cancer cells based on PARP cleavage and Annexin V staining. Compounds with a diphyllin structure similar to PHY34 have been shown to inhibit the ATP6V0A2 subunit of V(vacuolar)-ATPase. Therefore, ATP6V0A2 wild-type and ATP6V0A2 V823 mutant cell lines were tested with PHY34, and it was able to induce cell death in the wild-type at 246 pM while the mutant cells were resistant up to 55.46 nM. Overall, our data demonstrate that PHY34 is a promising small molecule for cancer therapy that targets the ATP6V0A2 subunit to induce autophagy inhibition while interacting with CAS and altering nuclear localization of proteins.

CSE1L promotes nuclear accumulation of transcriptional coactivator TAZ and enhances invasiveness of human cancer cells

The transcriptional coactivator with PDZ-binding motif (TAZ) (WWTR1) induces epithelial-mesenchymal transition and enhances drug resistance in multiple cancers. TAZ has been shown to interact with transcription factors in the nucleus, but when phosphorylated, translocates to the cytoplasm and is degraded through proteasomes. Here, we identified a compound TAZ inhibitor 4 (TI-4) that shifted TAZ localization to the cytoplasm independently of its phosphorylation. We used affinity beads to ascertain a putative target of TI-4, chromosomal segregation 1 like (CSE1L), which is known to be involved in the recycling of importin α and as a biomarker of cancer malignancy. We found that TI-4 suppressed TAZ-mediated transcription in a CSE1L-dependent manner. CSE1L overexpression increased nuclear levels of TAZ, whereas CSE1L silencing delayed its nuclear import. We also found via the in vitro coimmunoprecipitation experiments that TI-4 strengthened the interaction between CSE1L and importin α5 and blocked the binding of importin α5 to TAZ. WWTR1 silencing attenuated CSE1L-promoted colony formation, motility, and invasiveness of human lung cancer and glioblastoma cells. Conversely, CSE1L silencing blocked TAZ-promoted colony formation, motility, and invasiveness in human lung cancer and glioblastoma cells. In human cancer tissues, the expression level of CSE1L was found to correlate with nuclear levels of TAZ. These findings support that CSE1L promotes the nuclear accumulation of TAZ and enhances malignancy in cancer cells.

Circ_cse1l Inhibits Colorectal Cancer Proliferation by Binding to eIF4A3

Background

Circular RNAs (circRNAs) are involved in the growth of many tumors. However, the expression and possible role of circ_cse1l (hsa_circ_0060745) in colorectal cancer (CRC) are unclear. The present study was designed to explore the role of circ_cse1l in CRC.

Material/Methods

The levels of circ_cse1l expression in cancer tissues and serum samples of 50 patients with CRC and in control subjects were analyzed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). CCK-8, colony formation, transwell and wound healing assays were performed to assess the functions of circ_cse1l in CRC cell lines after overexpression. The relationship between circ_cse1l and eIF4A3 during cell proliferation was analyzed by western blotting and RNA-binding protein immunoprecipitation (RIP).

Results

qRT-PCR assays showed that the levels of expression of circ_cse1l were lower in CRC cell lines and in tissue and serum samples from patients with CRC than in control samples. The expression of circ_cse11 in CRC tissues had clinical significance, as its level of expression was inversely associated with the depth of tumor invasion. Overexpression of circ_cse1l in HT29 and HCT116 cells markedly reduced cell proliferation and metastasis. Western blotting showed that circ_cse1l overexpression dowregulated the expression of PCNA protein. RIP results demonstrated that circ_cse1l inhibited the proliferation of CRC cells by binding to eIF4A3.

Conclusions

The expression of circ_cse1l is downregulated in CRC. Furthermore, circ_cse1l downregulated PCNA expression by binding to eIF4A3, inhibiting the proliferation of CRC cells.

Expression of CAS/CSE1L, the Cellular Apoptosis Susceptibility Protein, Correlates With Neoplastic Progression in Barrett's Esophagus

BACKGROUND

Identifying the molecular switch responsible for the neoplastic progression of Barrett's esophagus (BE) and initiation of adenocarcinoma (ADC) is clinically essential and it will have a profound impact on patient diagnosis, prognosis, and treatment. The cellular apoptosis susceptibility gene CAS/CSE1L is overexpressed in various cancers, including a rare report on esophageal ADC; however, its expression in BE neoplasia has not been addressed.

MATERIALS AND METHODS

We investigated the expression of the CAS/CSE1L protein immunohistochemically in 56 esophageal resection specimens for ADC arising in BE. For each specimen, a full representative section of the invasive ADC was selected to include, when possible, BE, low-grade dysplasia (LGD) and high-grade dysplasia (HGD). Samples were stained for CAS/CSE1L expression using a rabbit polyclonal antibody recognizing the N-terminus of human CAS/CSE1L. Protein expression levels were measured using the Allred semiquantitative scoring system. The data were evaluated using χ statistical analysis. Gene expression Omnibus was queried for CAS/CSE1L and BE neoplasia.

RESULTS

We found minimal to absent CAS/CSE1L in all BE tissue samples; however, CAS/CSE1L was upregulated in 60% of LGD and overexpressed in HGD and ADC. The results were statistically significant (P<0.05). The localization of CAS/CSE1L protein was nuclear in BE; it became nuclear and cytoplasmic in LGD and HGD, and predominantly cytoplasmic in ADC. A similar progressive increase was observed for CAS/CSE1L gene expression.

CONCLUSION

These findings show changes in CAS/CSE1L during BE progression. CAS/CSE1L may represent a potential marker for dysplasia/carcinoma.

Expression of cellular apoptosis susceptibility (CAS) in the human testis and testicular germ cell tumors

Testicular germ cell tumors are the most frequent malignancies found in men between 15 and 44 years old. Although cellular apoptosis susceptibility (CAS) was demonstrated to be upregulated in breast cancer and colon cancer, the expression of CAS in the human testis and testicular germ cell tumors remained elusive. In the present study, CAS-positive signals were detected in the normal testicular tissues, cancer adjacent normal testicular tissues, seminoma, yolk sac tumor, and teratoma. Interestingly, the expression level of CAS in testicular germ cell tumors (TGCTs) (but not seminoma) was significantly lower than that of human testicular tissues and cancer adjacent normal testicular tissues, suggesting that decreased CAS contributed to the progression of TGCTs. Notably, the expression of CAS in seminoma was significantly higher than that of in the non-seminomas, consistent with the results from TCGA database. Furthermore, the localization of CAS is mainly restricted in the nucleus in the lesions of normal human testicular tissue and cancer adjacent normal testicular tissue. Although the expression of CAS was not significantly different between normal testicular tissue and seminoma, CAS was more enriched in cytoplasm in seminoma compared to the normal, cancer adjacent tissue and other types of TGCTs. The current results demonstrated reduced expression of CAS in the human testicular germ cell tumors and the CAS translocation from the nuclear to cytoplasm in seminoma, thereby supporting a possible role in normal testis function and in the development of seminoma.

CSE1L participates in regulating cell mitosis in human seminoma

Objectives

CSE1L has been reported to be highly expressed in various tumours. Testicular germ cell tumours are common among young males, and seminoma is the major type. However, whether CSE1L has functions in the seminoma is unclear.

Materials and methods

The expression of CSE1L was detected by immunohistochemistry in seminoma tissues and non‐tumour normal testis tissues from patients. CSE1L distribution during cell mitosis was determined by immunofluorescent staining with CSE1L, α‐tubulin and γ‐tubulin antibodies. The effects of Cse1L knockdown on cell proliferation and cell cycle progression were determined by Cell Counting Kit‐8 assay, flow cytometry, PH3 staining and bromodeoxyuridine incorporation assay.

Results

CSE1L was significantly enriched in the seminoma tissue compared with the non‐tumour normal testis tissue. CSE1L also co‐localized with α‐tubulin in the cells with a potential to divide. In the seminoma cell line TCam‐2, CSE1L was associated with the spindles and the centrosomes during cell division. The knockdown of CSE1L in TCam‐2 cells attenuated the cells’ proliferative capacity. Cell cycle assay revealed that the CSE1L‐deficient cells were mainly arrested in the G0/G1 phase and moderately delayed in the G2/M phase. The proportion of cells with multipolar spindle and abnormal spindle geometry was obviously increased by CSE1L expression silencing in the TCam‐2 cells.

Conclusions

Overall, these findings showed that CSE1L plays a pivotal role in maintaining cell proliferation and cell division in seminomas.

Controlling the Gatekeeper: Therapeutic Targeting of Nuclear Transport

Nuclear transport receptors of the karyopherin superfamily of proteins transport macromolecules from one compartment to the other and are critical for both cell physiology and pathophysiology. The nuclear transport machinery is tightly regulated and essential to a number of key cellular processes since the spatiotemporally expression of many proteins and the nuclear transporters themselves is crucial for cellular activities. Dysregulation of the nuclear transport machinery results in localization shifts of specific cargo proteins and associates with the pathogenesis of disease states such as cancer, inflammation, viral illness and neurodegenerative diseases. Therefore, inhibition of the nuclear transport system has future potential for therapeutic intervention and could contribute to the elucidation of disease mechanisms. In this review, we recapitulate clue findings in the pathophysiological significance of nuclear transport processes and describe the development of nuclear transport inhibitors. Finally, clinical implications and results of the first clinical trials are discussed for the most promising nuclear transport inhibitors.

Roles of the CSE1L-mediated nuclear import pathway in epigenetic silencing

Epigenetic silencing can be mediated by various mechanisms, and many regulators remain to be identified. Here, we report a genome-wide siRNA screening to identify regulators essential for maintaining gene repression of a CMV promoter silenced by DNA methylation. We identified CSE1L (chromosome segregation 1 like) as an essential factor for the silencing of the reporter gene and many endogenous methylated genes. CSE1L depletion did not cause DNA demethylation. On the other hand, the methylated genes derepressed by CSE1L depletion largely overlapped with methylated genes that were also reactivated by treatment with histone deacetylase inhibitors (HDACi). Gene silencing defects observed upon CSE1L depletion were linked to its nuclear import function for certain protein cargos because depletion of other factors involved in the same nuclear import pathway, including KPNAs and KPNB1 proteins, displayed similar derepression profiles at the genome-wide level. Therefore, CSE1L appears to be critical for the nuclear import of certain key repressive proteins. Indeed, NOVA1, HDAC1, HDAC2, and HDAC8, genes known as silencing factors, became delocalized into cytosol upon CSE1L depletion. This study suggests that the cargo specificity of the protein nuclear import system may impact the selectivity of gene silencing.

CAS (CSE1L) signaling pathway in tumor progression and its potential as a biomarker and target for targeted therapy

CSE1L (chromosome segregation 1-like protein), also named as CAS (cellular apoptosis susceptibility protein), is highly expressed in most cancer types. CSE1L/CAS is a multiple functional protein that plays roles in apoptosis, cell survival, chromosome assembly, nucleocytoplasmic transport, microvesicle formation, and cancer metastasis; some of the functions are explicitly correlated. CSE1L is also a cancer serum biomarker. The phosphorylation of CAS is regulated by the extracellular signal-regulated kinase (ERK). The RAS/RAF/MAPK/ERK signaling pathways are the essential targets of most targeted cancer drugs, thus serum phosphorylated CSE1L may be a potential biomarker for monitoring drug resistance in targeted therapy. CSE1L can regulate Ras-induced ERK phosphorylation. CSE1L also regulates the expression and phosphorylation of CREB (cAMP response element binding protein) and MITF (microphthalmia-associated transcription factor) and is thus involved in the melanogenesis and progression of melanoma. CAS is an exosome/microvesicle membrane protein. Tumor cells consistently secrete microvesicles and tumor-derived microvesicles may be accumulated around tumors. Therefore, microvesicle membrane CSE1L may be a potential target for the development of high-efficacy antibody-drug conjugates (ADCs) for cancer therapy. This review will focus on CSE1L expression in cancers, its relationship to Ras/ERK and cAMP/PKA signaling pathways in melanoma development, its potential for the development of ADCs and tumor imaging reagents, and secretory phosphorylated CSE1L for monitoring the emergence of drug resistance in targeted cancer therapy.

Targeting nuclear transporters in cancer: Diagnostic, prognostic and therapeutic potential

The Karyopherin superfamily is a major class of soluble transport receptors consisting of both import and export proteins. The trafficking of proteins involved in transcription, cell signalling and cell cycle regulation among other functions across the nuclear membrane is essential for normal cellular functioning. However, in cancer cells, the altered expression or localization of nuclear transporters as well as the disruption of endogenous nuclear transport inhibitors are some ways in which the Karyopherin proteins are dysregulated. The value of nuclear transporters in the diagnosis, prognosis and treatment of cancer is currently being elucidated with recent studies highlighting their potential as biomarkers and therapeutic targets.

Biological significance of the importin-β family-dependent nucleocytoplasmic transport pathways

Importin-β family proteins (Imp-βs) are nucleocytoplasmic transport receptors (NTRs) that import and export proteins and RNAs through the nuclear pores. The family consists of 14-20 members depending on the biological species, and each member transports a specific group of cargoes. Thus, the Imp-βs mediate multiple, parallel transport pathways that can be regulated separately. In fact, the spatiotemporally differential expressions and the functional regulations of Imp-βs have been reported. Additionally, the biological significance of each pathway has been characterized by linking the function of a member of Imp-βs to a cellular consequence. Connecting these concepts, the regulation of the transport pathways conceivably induces alterations in the cellular physiological states. However, few studies have linked the regulation of an importin-β family NTR to an induced cellular response and the corresponding cargoes, despite the significance of this linkage in comprehending the biological relevance of the transport pathways. This review of recent reports on the regulation and biological functions of the Imp-βs highlights the significance of the transport pathways in physiological contexts and points out the possibility that the identification of yet unknown specific cargoes will reinforce the importance of transport regulation.

CSE1L modulates Ras-induced cancer cell invasion: correlation of K-Ras mutation and CSE1L expression in colorectal cancer progression

BACKGROUND

Ras plays an important role in colorectal cancer progression. CSE1L (chromosome segregation 1-like) gene maps to 20q13, a chromosomal region that correlates with colorectal cancer development. We investigated the association of CSE1L with Ras in colorectal cancer progression.

METHODS

The effect of CSE1L on metastasis-stimulating activity of Ras was studied in an animal model with tumor cells expressing CSE1L-specific shRNA and v-H-Ras. CSE1L expression was evaluated by the immunohistochemical analysis of 127 surgically resected colorectal tumors. K-Ras mutations were analyzed by direct sequencing.

RESULTS

CSE1L knockdown reduced Ras-induced metastasis of B16F10 melanoma cells in C57BL/6 mice. v-H-Ras expression altered the cellular trafficking of CSE1L and increased CSE1L secretion. Most colorectal tumors were positive for CSE1L staining (98.4%, 125 of 127). Colorectal tumors with K-Ras mutation or high cytoplasmic CSE1L expression were correlated with T status (depth of tumor penetration; P = .004), stage (P = .004), and lymph node metastasis (P = .019).

CONCLUSIONS

CSE1L may be a target for treating Ras-associated tumors. Analysis of K-Ras mutation and CSE1L expression may provide valuable clinical and pathological information to aid in the determination of treatment options for colorectal cancer.

Correlations between cytoplasmic CSE1L in neoplastic colorectal glands and depth of tumor penetration and cancer stage

Background

Colorectal carcinomas spread easily to nearby tissues around the colon or rectum, and display strong potential for invasion and metastasis. CSE1L, the chromosome segregation 1-like protein, is implicated in cancer progression and is located in both the cytoplasm and nuclei of tumor cells. We investigated the prognostic significance of cytoplasmic vs. nuclear CSE1L expression in colorectal cancer.

Methods

The invasion- and metastasis-stimulating activities of CSE1L were studied by in vitro invasion and animal experiments. CSE1L expression in colorectal cancer was assayed by immunohistochemistry, with tissue microarray consisting of 128 surgically resected specimens; and scored using a semiquantitative method. The correlations between CSE1L expression and clinicopathological parameters were analyzed.

Results

CSE1L overexpression was associated with increased invasiveness and metastasis of cancer cells. Non-neoplastic colorectal glands showed minimal CSE1L staining, whereas most colorectal carcinomas (99.2%, 127/128) were significantly positive for CSE1L staining. Cytoplasmic CSE1L was associated with cancer stage (P=0.003) and depth of tumor penetration (P=0.007). Cytoplasmic CSE1L expression also correlated with lymph node metastasis of the disease in Cox regression analysis

Conclusions

CSE1L regulates the invasiveness and metastasis of cancer cells, and immunohistochemical analysis of cytoplasmic CSE1L in colorectal tumors may provide a useful aid to prognosis.

CSE1L, a novel microvesicle membrane protein, mediates Ras-triggered microvesicle generation and metastasis of tumor cells

Tumor-derived microvesicles are rich in metastasis-related proteases and play a role in the interactions between tumor cells and tumor microenvironment in tumor metastasis. Because shed microvesicles may remain in the extracellular environment around tumor cells, the microvesicle membrane protein may be the potential target for cancer therapy. Here we report that chromosome segregation 1-like (CSE1L) protein is a microvesicle membrane protein and is a potential target for cancer therapy. v-H-Ras expression induced extracellular signal-regulated kinase (ERK)-dependent CSE1L phosphorylation and microvesicle biogenesis in various cancer cells. CSE1L overexpression also triggered microvesicle generation, and CSE1L knockdown diminished v-H-Ras-induced microvesicle generation, matrix metalloproteinase (MMP)-2 and MMP-9 secretion and metastasis of B16F10 melanoma cells. CSE1L was preferentially accumulated in microvesicles and was located in the microvesicle membrane. Furthermore, anti-CSE1L antibody-conjugated quantum dots could target tumors in animal models. Our findings highlight a novel role of Ras-ERK signaling in tumor progression and suggest that CSE1L may be involved in the "early" and "late" metastasis of tumor cells in tumorigenesis. Furthermore, the novel microvesicle membrane protein, CSE1L, may have clinical utility in cancer diagnosis and targeted cancer therapy.

Presence of CSE1L protein in urine of patients with urinary bladder urothelial carcinomas

The chromosome segregation 1-like (CSE1L) protein is highly expressed in most cancers and has been shown to be secreted by tumor cells. We studied the presence of CSE1L in the urine of patients with bladder urothelial carcinomas. The results of our immunohistochemical analysis showed a high expression of CSE1L in bladder cancer specimens, while the normal bladder specimens only showed a very faint staining in some cells. Immunoblotting showed that CSE1L was present in urine of patients with bladder cancer. Urinary CSE1L-positive cases were detected in 95% (57/60) of patients with bladder urothelial carcinomas or the atypical/suspicious cases with urothelial atypia. No CSE1L was detected in urine of healthy controls (p<0.01). Our results suggest that urinary CSE1L deserves further evaluation for the screening of bladder cancer.