Overexpression of Karyopherin-2 in Epithelial Ovarian Cancer and Correlation With Poor Prognosis

Integration of the cancer cell secretome and transcriptome reveals potential noninvasive diagnostic markers for bladder cancer

PURPOSE

Bladder cancer (BLCA) is a major cancer of the genitourinary system. Although cystoscopy is the standard protocol for diagnosing BLCA clinically, this procedure is invasive and expensive. Several urine-based markers for BLCA have been identified and investigated, but none has shown sufficient sensitivity and specificity. These observations underscore the importance of discovering novel BLCA biomarkers and developing a noninvasive method for detection of BLCA. Exploring the cancer secretome is a good starting point for the development of noninvasive biomarkers for cancer diagnosis.

EXPERIMENTAL DESIGN

In this study, we established a comprehensive secretome dataset of five representative BLCA cell lines, BFTC905, TSGH8301, 5637, MGH-U1, and MGH-U4, by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Expression of BLCA-specific secreted proteins at the transcription level was evaluated using the Oncomine cancer microarray database.

RESULTS

The expressions of four candidates-COMT, EWSR1, FUSIP1, and TNPO2-were further validated in clinical human specimens. Immunohistochemical analyses confirmed that transportin-2 was highly expressed in tumor cells relative to adjacent noncancerous cells in clinical tissue specimens from BLCA patients, and was significantly elevated in BLCA urine compared with that in urine samples from aged-matched hernia patients (controls).

CONCLUSIONS

Collectively, our findings suggest TNPO2 as a potential noninvasive tumor-stage or grade discriminator for BLCA management.

Nuclear localization signal-tagged systems: relevant nuclear import principles in the context of current therapeutic design

Nuclear targeting of therapeutics provides a strategy for enhancing efficacy of molecules active in the nucleus and minimizing off-target effects. 'Active' nuclear-directed transport and efficient translocations across nuclear pore complexes provide the most effective means of maximizing nuclear localization. Nuclear-targeting systems based on nuclear localization signal (NLS) motifs have progressed significantly since the beginning of the current millennium. Here, we offer a roadmap for understanding the basic mechanisms of nuclear import in the context of actionable therapeutic design for developing NLS-therapeutics with improved treatment efficacy.

Distribution of importin-α isoforms in poultry species and their tissue- and age-related differences

While importin-α is well studied in mammals, the knowledge in avian species is still limited. In this study, we compared the mRNA expression patterns of five importin-α isoforms in the respiratory tract, liver, and spleen of chickens, turkeys, and pekin ducks in two different age-groups. In addition, we determined the distribution of importin-α in selected tissue of conchae, trachea, and lung of post-hatch chickens at all cellular levels by immunohistochemical staining. Our results indicate that importin-α3 is the most abundant isoform in the respiratory tract of chickens, turkeys, and pekin ducks. Moreover, importin-α is expressed as a gradient with lowest mRNA levels in the conchae and highest levels in the lung. The mRNA expression levels of most isoforms were higher in tissues from post-hatch chickens and turkeys in comparison to the corresponding embryos. In contrast to that, duck embryos mostly show higher mRNA expression levels of importin-α than post-hatch ducks.

KPNB1-mediated nuclear import in cancer

Dysregulation of nucleocytoplasmic shuttling impairs cellular homeostasis and promotes cancer development. KPNB1 is a member of karyopherin β family, mediating the transportation of proteins from the cytoplasm to the nucleus. In a variety of cancers, the expression of KPNB1 is upregulated to facilitate tumor growth and progression. Both downregulation of KPNB1 level and inhibition of KPNB1 activity prevent the entry of cancer-related transcription factors into the nucleus, subsequently suppressing the proliferation and metastasis of cancer cells. Currently, five KPNB1 inhibitors have been reported and exhibited good efficacy against cancer. This paper provides an overview of the role and mechanism of KPNB1 in different cancers and KPNB1-targeted anticancer compounds which hold promise for the future.

Novel roles of karyopherin subunit alpha 2 in hepatocellular carcinoma

Hepatocellular carcinoma is the most common type of liver cancer and associated with a high fatality rate. This disease poses a major threat to human health worldwide. A considerable number of genetic and epigenetic factors are involved in the development of hepatocellular carcinoma. However, the molecular mechanism underlying the progression of hepatocellular carcinoma remains unclear. Karyopherin subunit alpha 2 (KPNA2), also termed importin α1, is a member of the nuclear transporter family. In recent years, KPNA2 has been gradually linked to the nuclear transport pathway for a variety of tumor-associated proteins. Furthermore, it promotes tumor development by participating in various pathophysiological processes such as cell proliferation, apoptosis, immune response, and viral infection. In hepatocellular carcinoma, it has been found that KPNA2 expression is significantly higher in liver cancer tissues versus paracancerous tissues. Moreover, it has been identified as a marker of poor prognosis and early recurrence in patients with hepatocellular carcinoma. Nevertheless, the role of KPNA2 in the development of hepatocellular carcinoma remains to be determined. This review summarizes the current knowledge on the pathogenesis and role of KPNA2 in hepatocellular carcinoma, and provides new directions and strategies for the diagnosis, treatment, and prediction of prognosis of this disease.

Acetylation regulates the nucleocytoplasmic distribution and oncogenic function of karyopherin alpha 2 in lung adenocarcinoma

Karyopherin subunit alpha 2 (KPNA2, importin α1) is a nucleoplasmic protein responsible for the nuclear import of proteins with classical nuclear localization signals. Aberrant nuclear accumulation of KPNA2 has been observed in numerous cancer tissues. AMP-activated protein kinase (AMPK) is involved in the phosphorylation and acetylation of KPNA2 in enterocytes. However, the impact of these post-translational modifications on modulating the nucleocytoplasmic distribution of KPNA2 and its oncogenic role remain unclear. Unlike nuclear accumulation of wild-type KPNA2, which promoted lung cancer cell migration, KPNA2 Lys22 acetylation-mimicking mutations (K22Q and K22Q/S105A) prevented nuclear localization of KPNA2 and reduced the cell migration ability. Cytosolic KPNA2 K22Q interacted with and restricted the nuclear entry of E2F transcription factor 1 (E2F1), an oncogenic cargo protein of KPNA2, in lung cancer cells. Intriguingly, the AMPK activator EX229 promoted the nuclear export of KPNA2 S105A. However, the CBP/p300 inhibitor CCS-1477 abolished this phenomenon, suggesting that CBP/p300-mediated acetylation of KPNA2 promoted KPNA2 nuclear export in lung cancer cells. Collectively, our findings suggest that the CBP/p300 positively regulates KPNA2 acetylation, which enhances its cytosolic localization and suppresses its oncogenic activity in lung cancer.

Circulating cell-free messenger RNA enables non-invasive pan-tumour monitoring of melanoma therapy independent of the mutational genotype

BACKGROUND

Plasma-derived tumour-specific cell-free nucleic acids are increasingly utilized as a minimally invasive, real-time biomarker approach in many solid tumours. Circulating tumour DNA of melanoma-specific mutations is currently the best studied liquid biopsy biomarker for melanoma. However, the combination of hotspot genetic alterations covers only around 80% of all melanoma patients. Therefore, alternative approaches are needed to enable the follow-up of all genotypes, including wild-type.

METHODS

We identified KPNA2, DTL, BACE2 and DTYMK messenger RNA (mRNA) upregulated in melanoma versus nevi tissues by unsupervised data mining (N = 175 melanoma, N = 20 normal skin, N = 6 benign nevi) and experimentally confirmed differential mRNA expression in vitro (N = 18 melanoma, N = 8 benign nevi). Circulating cell-free RNA (cfRNA) was analysed in 361 plasma samples (collected before and during therapy) from 100 melanoma patients and 18 healthy donors. Absolute cfRNA copies were quantified on droplet digital PCR.

RESULTS

KPNA2, DTL, BACE2 and DTYMK cfRNA demonstrated high diagnostic accuracy between melanoma patients' and healthy donors' plasma (AUC > 86%, p < .0001). cfRNA copies increased proportionally with increasing tumour burden independently of demographic variables and even remained elevated in individuals with radiological absence of disease. Re-analysis of single-cell transcriptomes revealed a pan-tumour origin of cfRNA, including endothelial, cancer-associated fibroblasts, macrophages and B cells beyond melanoma cells as cellular sources. Low baseline cfRNA levels were associated with significantly longer progression-free survival (PFS) (KPNA2 HR = .54, p = .0362; DTL HR = .60, p = .0349) and overall survival (KPNA2 HR = .52, p = .0237; BACE2 HR = .55, p = .0419; DTYMK HR = .43, p = .0393). Lastly, we found that cfRNA copies significantly increased during therapy in non-responders compared to responders regardless of therapy and mutational subtypes and that the increase of KPNA2 (HR = 1.73, p = .0441) and DTYMK (HR = 1.82, p = .018) cfRNA during therapy was predictive of shorter PFS.

CONCLUSIONS

In sum, we identified a new panel of cfRNAs for a pan-tumour liquid biopsy approach and demonstrated its utility as a prognostic, therapy-monitoring tool independent of the melanoma mutational genotype.

Recognition motifs for importin 4 [(L)PPRS(G/P)P] and importin 5 [KP(K/Y)LV] binding, identified by bio-informatic simulation and experimental in vitro validation

Nuclear translocation of large proteins is mediated through karyopherins, carrier proteins recognizing specific motifs of cargo proteins, known as nuclear localization signals (NLS). However, only few NLS signals have been reported until now. In the present work, NLS signals for Importins 4 and 5 were identified through an unsupervised in silico approach, followed by experimental in vitro validation. The sequences LPPRS(G/P)P and KP(K/Y)LV were identified and are proposed as recognition motifs for Importins 4 and 5 binding, respectively. They are involved in the trafficking of important proteins into the nucleus. These sequences were validated in the breast cancer cell line T47D, which expresses both Importins 4 and 5. Elucidating the complex relationships of the nuclear transporters and their cargo proteins is very important in better understanding the mechanism of nuclear transport of proteins and laying the foundation for the development of novel therapeutics, targeting specific importins.

Multiple roles of apolipoprotein B mRNA editing enzyme catalytic subunit 3B (APOBEC3B) in human tumors: a pan-cancer analysis

Although there have been some recent cell and animal experiments indicating that expression of the gene encoding apolipoprotein B mRNA editing enzyme catalytic subunit 3B (APOBEC3B) is closely related to cancer, it still lacks pan-cancer analysis. Here we analyzed the potential carcinogenic role of APOBEC3B in 33 tumors based on The Cancer Genome Atlas (TCGA). APOBEC3B was highly expressed in most tumors and weakly expressed in a few. Differences in expression level were significantly correlated with the pathological tumor stage and prognosis of affected patients. The high-frequency APOBEC3B changes were principally mutations and amplifications in some tumors, such as uterine corpus endometrial carcinomas or cutaneous melanomas. In testicular germ cell tumors and invasive breast carcinomas, APOBEC3B expression and CD8⁺ T lymphocyte counts were correlated. In other cancers, such as human papilloma virus (HPV)-related head and neck squamous cell carcinomas or esophageal adenocarcinomas, there was also cancer-associated fibroblast infiltration. The APOBEC3B enzyme acts in the mitochondrial respiratory electron transport chain and in oxidative phosphorylation. This first pan-cancer study provides a comprehensive understanding of the multiple roles of APOBEC3B in different tumor types.

mRNA-miRNA bipartite networks reconstruction in different tissues of bladder cancer based on gene co-expression network analysis

Bladder cancer (BC) is one of the most important cancers worldwide, and if it is diagnosed early, its progression in humans can be prevented and long-term survival will be achieved accordingly. This study aimed to identify novel micro-RNA (miRNA) and gene-based biomarkers for diagnosing BC. The microarray dataset of BC tissues (GSE13507) listed in the GEO database was analyzed for this purpose. The gene expression data from three BC tissues including 165 primary bladder cancer (PBC), 58 normal looking-bladder mucosae surrounding cancer (NBMSC), and 23 recurrent non-muscle invasive tumor tissues (RNIT) were used to reconstruct gene co-expression networks. After preprocessing and normalization, deferentially expressed genes (DEGs) were obtained and used to construct the weighted gene co-expression network (WGCNA). Gene co-expression modules and low-preserved modules were extracted among BC tissues using network clustering. Next, the experimentally validated mRNA-miRNA interaction information were used to reconstruct three mRNA-miRNA bipartite networks. Reactome pathway database and Gene ontology (GO) was subsequently performed for the extracted genes of three bipartite networks and miRNAs, respectively. To further analyze the data, ten hub miRNAs (miRNAs with the highest degree) were selected in each bipartite network to reconstruct three bipartite subnetworks. Finally, the obtained biomarkers were comprehensively investigated and discussed in authentic studies. The obtained results from our study indicated a group of genes including PPARD, CST4, CSNK1E, PTPN14, ETV6, and ADRM1 as well as novel miRNAs (e.g., miR-16-5p, miR-335-5p, miR-124-3p, and let-7b-5p) which might be potentially associated with BC and could be a potential biomarker. Afterward, three drug-gene interaction networks were reconstructed to explore candidate drugs for the treatment of BC. The hub miRNAs in the mRNA-miRNA bipartite network played a fundamental role in BC progression; however, these findings need further investigation.

Oncogenic role of karyopherin α2 (KPNA2) in human tumors: A pan-cancer analysis

BACKGROUND

KPNA2, a nuclear export protein that plays an important role in tumorigenesis, is an emerging hotspot target in oncology. Despite increasing supporting evidence of its importance, no pan-cancer analysis, across multiple databases, is available for in-depth data mining of the gene.

METHODS

Tumor data from both The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) were explored to investigate the potential oncogenic roles of KPNA2. Diverse analytical methods were used to gain a full-scale understanding of KPNA2: gene expression, survival situations, genetic mutations, DNA methylation, sites of protein phosphorylation, immunocyte infiltration, and correlative cellular pathways.

RESULTS

KPNA2 is highly expressed in many cancers, and different correlations exist between KPNA2 expression and prognosis of cancer patients. cBioPortal reported that a nonsense mutation of R285* was considered to be the primary tumorigenic genetic alteration to KPNA2 and was found in cases of LUSC, STAD, and CESC. Enhanced phosphorylation of S62 was found in several cancers and the level of infiltration of cancer-associated fibroblasts was found to be linearly correlated with KPNA2 expression levels in ACC, BRCA, MESO, TGCT, THCA, and THYM. Correlations between KPNA2 DNA methylation and the pathogenesis of various tumors in TCGA were further identified. KEGG and GO enrichment analysis identified cell cycle, microtubule binding, and tubulin binding functions for KPNA2.

CONCLUSION

This is the first pan-cancer analysis focusing on KPNA2. It provides a comprehensive understanding about the role of KPNA2 in tumorigenesis and highlights the potential targeted role of KPNA2 for cancer study.

Nuclear transport proteins are secreted by cancer cells and identified as potential novel cancer biomarkers

Previous studies have identified increased expression of members of the nuclear transport protein family in cancer cells. Recently, certain nuclear transport proteins have been reported to be secreted by cells and found in the serum. The aims of our study were to investigate the levels of multiple nuclear transport proteins secreted from cancer cells, and to determine their potential as diagnostic markers for cervical and oesophageal cancer. Mass spectrometry identified 10 nuclear transport proteins in the secretome and exosomes of cultured cancer cells, and Western blot analysis confirmed increased secreted levels in cancer cells compared to normal. To investigate their presence in patient serum, enzyme-linked immunosorbent assays were performed and revealed significantly increased levels of KPNβ1, CRM1, CAS, IPO5 and TNPO1 in cervical and oesophageal cancer patient serum compared to non-cancer controls. Significantly elevated KPNα2 and RAN levels were also identified in oesophageal cancer serum samples. Logistics regression analyses revealed IPO5 and TNPO1 to be the best performing individual candidate biomarkers in discriminating between cancer cases and controls. The combination of KPNβ1, CRM1, KPNα2, CAS, RAN, IPO5 and TNPO1 as a panel of biomarkers had the highest diagnostic capacity with an area under the curve of 0.944 and 0.963, for cervical cancer and oesophageal cancer, and sensitivity of 92.5% at 86.8% specificity and 95.3% sensitivity at 87.5% specificity, respectively. These results suggest that nuclear transport proteins have potential as diagnostic biomarkers for cervical and oesophageal cancers, with a combination of protein family members being the best predictor.

Applications of Multi-omics Approaches for Exploring the Molecular Mechanism of Ovarian Carcinogenesis

Ovarian cancer ranks as the fifth most common cause of cancer-related death in females. The molecular mechanisms of ovarian carcinogenesis need to be explored in order to identify effective clinical therapies for ovarian cancer. Recently, multi-omics approaches have been applied to determine the mechanisms of ovarian oncogenesis at genomics (DNA), transcriptomics (RNA), proteomics (proteins), and metabolomics (metabolites) levels. Multi-omics approaches can identify some diagnostic and prognostic biomarkers and therapeutic targets for ovarian cancer, and these molecular signatures are beneficial for clarifying the development and progression of ovarian cancer. Moreover, the discovery of molecular signatures and targeted therapy strategies could noticeably improve the prognosis of ovarian cancer patients.

KPNA2 promotes renal cell carcinoma proliferation and metastasis via NPM

Karyopherin α2 (KPNA2), involved in nucleocytoplasmic transport, has been reported to be up‐regulated in tumorigenesis. However, comprehensive studies of KPNA2 functions in renal cell carcinoma (RCC) are still lacking. In this study, we aim to investigate the roles of KPNA2 in kidney tumour development. Our results showed that down‐regulation of KPNA2 inhibited the proliferation and invasion of kidney tumour cell cells in vitro, while the cell cycle arrest and cellular apoptosis were induced once KPNA2 was silenced. Repression of KPNA2 was proved to be efficient to repress tumorigenesis and development of kidney tumour in in nude mice. Furthermore, one related participator, NPM, was identified based on Co‐IP/MS and bioinformatics analyses. The up‐regulation of NPM attenuates the efficiency of knockdown KPNA2. These results indicated that KPNA2 may regulate NPM to play a crucial role for kidney tumour development.

Oncogenes in high grade serous adenocarcinoma of the ovary

High grade serous ovarian cancer is characterized by relatively few mutations occurring at low frequency, except in TP53. However other genetic aberrations such as copy number variation alter numerous oncogenes and tumor suppressor genes. Oncogenes are positive regulators of tumorigenesis and play a critical role in cancer cell growth, proliferation, and survival. Accumulating evidence suggests that they are crucial for the development and the progression of high grade serous ovarian carcinoma (HGSOC). Though many oncogenes have been identified, no successful inhibitors targeting these molecules and their associated pathways are available. This review discusses oncogenes that have been identified recently in HGSOC using different screening strategies. All the genes discussed in this review have been functionally characterized both in vitro and in vivo and some of them are able to transform immortalized ovarian surface epithelial and fallopian tube cells upon overexpression. However, it is necessary to delineate the molecular pathways affected by these oncogenes for the development of therapeutic strategies.

Zika virus NS2A protein induces the degradation of KPNA2 (karyopherin subunit alpha 2) via chaperone-mediated autophagy

KPNA2/importin-alpha1 (karyopherin subunit alpha 2) is the primary nucleocytoplasmic transporter for some transcription factors to activate cellular proliferation and differentiation. Aberrant increase of KPNA2 level is identified as a prognostic marker in a variety of cancers. Yet, the turnover mechanism of KPNA2 remains unknown. Here, we demonstrate that KPNA2 is degraded via the chaperone-mediated autophagy (CMA) and that Zika virus (ZIKV) enhances the KPNA2 degradation. KPNA2 contains a CMA motif, which possesses an indispensable residue Gln109 for the CMA-mediated degradation. RNAi-mediated knockdown of LAMP2A, a vital component of the CMA pathway, led to a higher level of KPNA2. Moreover, ZIKV reduced KPNA2 via the viral NS2A protein, which contains an essential residue Thr100 for inducing the CMA-mediated KPNA2 degradation. Notably, mutant ZIKV with T100A alteration in NS2A replicates much weaker than the wild-type virus. Also, knockdown of KPNA2 led to a higher ZIKV viral yield, which indicates that KPNA2 mediates certain antiviral effects. These data provide insights into the KPNA2 turnover and the ZIKV-cell interactions.

Inhibiting Importin 4-mediated nuclear import of CEBPD enhances chemosensitivity by repression of PRKDC-driven DNA damage repair in cervical cancer

Cervical cancer (CC) remains highest in the mortality of female reproductive system cancers, while cisplatin (CDDP) resistance is the one of main reasons for the lethality. Preceding evidence has supported that karyopherins are associated with chemoresistance. In this study, we simultaneously compared CDDP-incomplete responders with CDDP-complete responders of CC patients and CDDP‐insensitive CC cell lines with CDDP‐sensitive group. We finally identified that DNA-PKcs (PRKDC) was related to CDDP sensitivity after overlapping in CC sample tissues and CC cell lines. Further functional assay revealed that targeting PRKDC by shRNA and NU7026 (specific PRKDC inhibitor) could enhance CDDP sensitivity in vitro and in vivo, which was mediated by impairing DNA damage repair pathway in CC. Mechanistically, we found that PRKDC was transcriptionally upregulated by CCAAT/enhancer-binding protein delta (CEBPD), while intriguingly, CDDP treatment strengthened the transcriptional activity of CEBPD to PRKDC. We further disclosed that Importin 4 (IPO4) augmented the nuclear translocation of CEBPD through nuclear localization signals (NLS) to activate PRKDC-mediated DNA damage repair in response to CDDP. Moreover, we demonstrated that IPO4 and CEBPD knockdown improved CDDP-induced cytotoxicity in vitro and in vivo. Together, we shed the novel insight into the role of IPO4 in chemosensitivity and provide a clinical translational potential to enhance CC chemosensitivity since the IPO4-CEBPD-PRKDC axis is actionable via NU7026 (PRKDC inhibitor) or targeting IPO4 in combination with CDDP.

Karyopherin α 2 promotes proliferation, migration and invasion through activating NF-κB/p65 signaling pathways in melanoma cells

AIMS

Melanoma is a fatal malignancy. Karyopherin α 2 (KPNA2) plays an important role in many carcinogenesis. This study was aimed to study the role of KPNA2 in cellular functions and molecular mechanisms of melanoma.

MAIN METHODS

We investigated the expression and prognosis of KPNA2 in melanoma using the GEPIA database (http://gepia.cancer-pku.cn/). The effect of KPNA2 on melanoma cells was determined using real-time PCR, western blot, immunofluorescence assay, CCK-8, colony formation, wound healing assay, transwell assay, EMSA, and immunohistochemistry. The influence of KPNA2 on the tumorigenicity of melanoma cells was evaluated in a nude mice model in vivo.

KEY FINDINGS

Our results showed that KPNA2 expression is relatively high in melanoma tissues and cells, and melanoma patients with higher expression of KPNA2 had lower overall survival rate and disease free survival rate. KPNA2 promoted proliferation ability and increased the expression of PCNA, Ki67, and C-MYC in melanoma cells. Further, KPNA2 could promote migration and invasion and increase the expression of MMP2 and MMP9. Mechanism studies showed that KPNA2 activated NF-κB/p65 signaling pathways, as evidenced by the nuclear translocation of p65 and increased the expression of COX-2, ICAM-1, iNOS, and MCP1 in melanoma cells. NF-κB inhibitor JSH-23 could reverse the pro-tumor effects of KPNA2 on melanoma cells. Moreover, upregulation of KPNA2 facilitated the tumorigenicity of melanoma cells.

SIGNIFICANCE

KPNA2 promotes proliferation, migration and invasion through enhancing NF-κB/p65 signaling pathways in melanoma cells. Our study suggests KPNA2 as a potential therapeutic target for the treatment of melanoma.

The emerging roles of KPNA2 in cancer

Karyopherin α2 (KPNA2, also known as importinα-1), a member of the nuclear transporter family, is involved in the nucleocytoplasmic transport pathway of a variety of tumor-associated proteins. Recent studies have found that KPNA2 is overexpressed in various cancers, which is associated with poor prognosis. In addition, it has been shown to promote tumor formation and progression by participating in cell differentiation, proliferation, apoptosis, immune response, and viral infection. It is indicated that KPNA2 also plays an important role in the diagnosis, treatment and prognosis of tumors. Herein, we provide an overview of the function and mechanism of KPNA2 in cancer and the prospects in the diagnosis and treatment of cancer. In the future, KPNA2 provides new ideas for the early diagnosis of malignant tumors, the development of molecularly targeted drugs, and prognosis evaluation.

HCV infection causes cirrhosis in human by step-wise regulation of host genes involved in cellular functioning and defense during fibrosis: Identification of bio-markers

Chronic Hepatitis C Viral (HCV) infection is a leading health problem worldwide and resulted in fibrotic scar formation, and finally liver-cirrhosis. Although contemporary therapies can partially reverse this destructive process, the rehabilitation is too slow and unsuitable for all chronic infections. The current study elucidates the mechanism of disease progression from early (F1) to moderate (F2, F3), and to severe fibrosis (F4)/cirrhosis in HCV genotype 3a infected patients to find out new candidates as potential disease progression markers and antiviral therapeutic agents. A total of 550 genes were found differentially regulated in the four fibrosis stages and grouped in 22 classes according to their biological functions. Gene set enrichment (GSEA) and Ingenuity pathway analysis (IPA) were used to identify the regulation of crucial biological functions and pathways involved in HCV progression. HCV differentially regulated the expression of genes involved in apoptosis, cell structure, signal transduction, proliferation, metabolism, cytokine signaling, immune response, cell adhesion and maintenance, and post translational modifications by pathway analysis. There was an increasing trend of proliferative and cell growth related genes and shutting down of immune response as the disease progress mild to moderate to advanced stage cirrhosis. The myriad of changes in gene expression showed more chances of developing liver cancer in patients infected with HCV genotype 3a in a systematic manner. The identified gene set can act as disease markers for prediction, whether the fibrosis lead to cirrhosis and its association with end stage liver disease development.

Importin-4 functions as a driving force in human primary gastric cancer

OBJECTIVES

Importin-4 (IPO4) is responsible for transporting histones H3 and H4 into the nucleus for chromatin assembly. But, the role of IPO4 in cancer, especially in gastric cancer (GC), has not been fully understood. We aim to determine the expression and function of IPO4 in GC.

MATERIALS AND METHODS

Bioinformatics analysis was used to study the association of IPO4 and GC using GEO data and the Kaplan-Meier plotter. The quantitative real-time polymerase chain reaction and Western blot analysis were used to determine the IPO4 level in GC cells and tissues. Small interfering RNAs (siRNAs) were used to knockdown endogenous IPO4 expression in GC cells. Cell counting kit-8 (CCK-8), colony formation and transwell assays were used to examine the effect of IPO4 on cell proliferation and migration.

RESULTS

IPO4 mRNA is overexpressed in GC tissues using bioinformatics analysis of three groups' transcriptome data, and high level of IPO4 is negatively correlated with poor long-term survival using the Kaplan-Meier plotter analysis. Western blot analysis further shows that IPO4 protein levels are also overexpressed in GC tissues and a number of GC cell lines. Endogenous IPO4 level can be inhibited by specific siRNA effectively. Importantly, CCK-8, colony formation, and transwell assays demonstrate that IPO4 knockdown by siRNA impairs GC cell proliferation and migration.

CONCLUSIONS

Our data suggest that IPO4 contributes to GC progression and poor prognosis, and may function as a driving force in GC progression.

Silencing of the nucleocytoplasmic shuttling protein karyopherin a2 promotes cell-cycle arrest and apoptosis in glioblastoma multiforme

We have previously shown that the nucleocytoplasmic carrier karyopherin a2 (KPNA2) is overexpressed in glioblastoma multiforme (GBM) whereas its expression is inversely associated with patient prognosis. However, the promoting role of KPNA2 in gliomagenesis is still poorly understood. This study aims to further elucidate this role of KPNA2 in in vitro GBM models.

From four different tested GBM cell lines, the U87MG showed the highest proliferation, low adherence and outgrowth in 3D clusters as well as the highest expression of KPNA2, all features conferring greater malignant behaviour. Silencing of KPNA2 via siRNA interference in those cells significantly decreased their proliferative capacity (p = 0.001). We further observed both a significant cell cycle phase arrest (p = 0.040) and the promoting of cellular apoptosis (p = 0.016) as well as a strong trend (p = 0.062) for an inhibition of nuclear import of c-Myc.

This study confirms that a higher expression of KPNA2 in GBM is associated with a more malignant phenotype also in in vitro models. While increased expression of KPNA2 promotes proliferation and survival of GBM tumour cells, silencing of KPNA2 conferred a less malignant behaviour. Our results strongly suggest that silencing of KPNA2 may play an important role in modulation of malignant features of GBM cells.

Association of overexpressed karyopherin alpha 2 with poor survival and its contribution to interleukin-1β-induced matrix metalloproteinase expression in oral cancer

BACKGROUND

The purpose of this study was to elucidate the clinicopathological associations and molecular mechanisms of karyopherin alpha 2 (KPNA2) in oral cavity squamous cell carcinoma (SCC) progression.

METHODS

The KPNA2 expressions were analyzed by immunohistochemistry and enzyme-linked immunosorbent assay in 209 tissues and 181 saliva samples, respectively. The functions of KPNA2 in migration and invasion were examined in KPNA2-knowdown cells. The matrix metalloproteinase (MMP) levels were determined by real-time quantitative polymerase chain reaction (qPCR). The subcellular fraction was used to obtain the nuclear distribution of nuclear factor-kappa B (NF-κB).

RESULTS

The KPNA2 overexpression was associated with extranodal extension (P < .05) and poor disease-specific survival in patients with oral cavity SCC (P < .05). The salivary KPNA2 levels were elevated in patients with oral cavity SCC (P < .05). The KPNA2 knockdown reduced cell migration and invasion. This knockdown also suppressed the interleukin (IL)-1β-induced nuclear import of NF-κB and MMP (MMP-1, MMP-3, and MMP-9) transcription.

CONCLUSION

The KPNA2 overexpression is an independent biomarker for poor prognosis of oral cavity SCC and is required for MMP-mediated metastasis.

Prognostic value of increased KPNA2 expression in some solid tumors: A systematic review and meta-analysis

Background

Karyopherin α2 (KPNA2), a member of the Karyopherin α family, has recently been reported to play an important role in tumor progression. However, the association between KPNA2 expression and prognosis in cancer remains controversial. So we performed this meta-analysis to evaluate whether expression of KPNA2 was associated with prognosis in patients with solid tumor.

Methods/Findings

24 published eligible studies, including 6164 cases, were identified and included in this meta-analysis through searching of PubMed, EMBASE and Web of Science. We found that KPNA2 expression was an independent predictor for the prognosis of solid tumor with primary outcome (overall survival [OS]: pooled HR=1.767, 95% CI=1.503-2.077, P<0.001) and secondary outcomes (time to recurrence [TTR], recurrence free survival [RFS] and progression free survival [PFS]). However, the association between KPNA2 overexpression and disease free survival [DFS] in solid tumors was not significant (pooled HR=1.653, 95% CI=0.903-3.029, P=0.104). Furthermore, the subgroup analysis revealed that KPNA2 overexpression was associated with poor OS in East-Asian patients and European patients, as well as patients with gastric and colorectal cancer.

Conclusion

KPNA2 expression may be a useful prognostic biomarker to monitor cancer prognosis. Further prospective studies with larger sample sizes are required to confirm our findings.

mTOR regulates proteasomal degradation and Dp1/E2F1- mediated transcription of KPNA2 in lung cancer cells

Karyopherin subunit alpha-2 (KPNA2) is overexpressed in various human cancers and is associated with cancer invasiveness and poor prognosis in patient. Nevertheless, the regulation of KPNA2 expression in cancers remains unclear. We herein applied epidermal growth factor (EGF) and five EGF receptor (EGFR)-related kinase inhibitors to investigate the role of EGFR signaling in KPNA2 expression in non-small cell lung cancer (NSCLC) cells. We found that EGFR signaling, particularly the mammalian target of rapamycin (mTOR) activity was positively correlated with KPNA2 protein levels in NSCLC cells. The mTOR inhibitors and mTOR knockdown reduced the protein and mRNA levels of KPNA2 in NSCLC and breast cancer cells. Specifically, rapamycin treatment induced proteasome-mediated KPNA2 protein decay and attenuated the transcriptional activation of KPNA2 by decreasing Dp1/E2F1 level in vivo. Immunoprecipitation assay further revealed that KPNA2 physically associated with the phospho-mTOR/mTOR and this association was abolished by rapamycin treatment. Collectively, our results show for the first time that KPNA2 is transcriptionally and post-translationally regulated by the mTOR pathway and provide new insights into targeted therapy for NSCLC.

Potential microRNA-related Targets for Therapeutic Intervention with Ovarian Cancer Metastasis

Treatment of disseminated epithelial ovarian cancer (EOC) is an unmet medical need. Therefore, the identification along with preclinical and clinical validation of new targets is an issue of high importance. In this review we focus on microRNAs that mediate metastasis of EOC. We summarize up-regulated metastasis-promoting and down-regulated metastasis-suppressing microRNAs. We focus on preclinical in vitro and in vivo functions as well as their metastasis-related clinical correlations. Finally, we outline modalities for therapeutic intervention and critical issues of microRNA-based therapeutics in the context of metastatic EOC.

KPNA2 promotes migration and invasion in epithelial ovarian cancer cells by inducing epithelial-mesenchymal transition via Akt/GSK-3β/Snail activation

Background: Increased karyopherin alpha 2 (KPNA2) expression has been demonstrated in epithelial ovarian carcinoma (EOC) tissue. However, its role in the disease is not clear. Here, we investigate the mechanism of involvement of KPNA2 in EOC.

Methods: Stable cell lines expressing KPNA2, or KPNA2 shRNAs, were constructed. The effects of KPNA2 overexpression and knockdown on EOC cell migration, invasion, and epithelial-to-mesenchymal transition (EMT) were evaluated using relevant assays and western blot analysis. Key components of the Akt/GSK-3β/Snail signaling pathway were detected using western blotting and immunofluorescence.

Results: KPNA2 overexpression increased the migration and invasion of EOC cells (EFO-21 and SK-OV3); these cells also exhibited characteristics of EMT. Key proteins in the Akt/GSK-3β/Snail signaling pathway were also upregulated in cells overexpressing KPNA2. In contrast, knockdown of KPNA2 effectively suppressed migration and invasion of these EOC cells.

Conclusions: KPNA2 may reduce the migration and invasion of EOC by inhibiting the Akt/GSK-3β/Snail signaling pathway and suppressing EMT.

Karyopherin α-2 is a reliable marker for identification of patients with high-risk stage II colorectal cancer

PURPOSE

Adjuvant chemotherapy (AC) is frequently considered in patients with high-risk stage II colorectal cancer (CRC). Among patients with stage II CRC who do not receive AC because they are not considered to be at high risk, 20-25% will develop recurrence and die from the disease. Elevated levels of KPNA2 have been observed in various cancers, and overexpression of KPNA2 is related to CRC progression.

METHODS

We examined the expression of KPNA2 using 293 CRC tissues, including 118 with stage II CRC, and investigated the applicability of KPNA2 as a biomarker to predict high-risk stage II CRC. Moreover, we further investigated the role of KPNA2 as an oncogene in CRC carcinogenesis using in vitro functional studies.

RESULTS

High KPNA2 expression was associated with vascular (p = 0.027) and lymphatic invasion (p = 0.009) in patients with stage II CRC. On multivariate analysis, high KPNA2 expression (HR 3.174, 95% CI 2.060-4.889; p < 0.001) was independently associated with survival in patients with CRC. The overall survival rate in patients with high KPNA2 expression was higher than that in patients with low KPNA2 expression in CRC (p < 0.001), even in patients with stage II CRC (p = 0.001). Additionally, KPNA2 was associated with tumorigenesis and cancer progression in CRC cells; high KPNA2 expression was associated with increased cell proliferation (p < 0.05), migration (p = 0.03), invasion (p = 0.001), and semisolid agar colony formation (p < 0.001).

CONCLUSION

KPNA2 expression is useful for identification of patients with high-risk stage II CRC who could benefit from AC and that KPNA2 may also be a promising therapeutic target.

KPNA2 is a potential diagnostic serum biomarker for epithelial ovarian cancer and correlates with poor prognosis

This study aimed to determine whether serum karyopherin alpha 2 levels can be used as a diagnostic biomarker for epithelial ovarian carcinoma. Karyopherin alpha 2 protein was detected by enzyme-linked immunosorbent assay in serum samples from 162 epithelial ovarian carcinoma patients and 48 healthy controls. Serum karyopherin alpha 2 levels in epithelial ovarian carcinoma patients were significantly higher than in healthy controls ( p < 0.001). When a karyopherin alpha 2 serum level of 2.52 µg/mL was used as a cut-off, the sensitivity and specificity of the assay for diagnosing epithelial ovarian carcinoma were 71.4% and 81.2%, respectively. High serum karyopherin alpha 2 levels (>485 µg/mL) correlated with International Federation of Gynecology and Obstetrics stage ( p < 0.0001), lymphatic metastasis ( p = 0.045), overall survival ( p = 0.001), and disease-free progression ( p = 0.006). Serum karyopherin alpha 2 represents a potential diagnostic biomarker for epithelial ovarian carcinoma.

Silencing of karyopherin α2 inhibits cell growth and survival in human hepatocellular carcinoma

Karyopherin α2 (KPNA2), involved in nucleocytoplasmic transport, has been reported to be upregulated in hepatocellular carcinoma and considered as a biomarker for poor prognosis. However, comprehensive studies of KPNA2 functions in hepatocellular carcinogenesis are still lacking. Our study examine the roles and related molecular mechanisms of KPNA2 in hepatocellular carcinoma development. Results show that KPNA2 knockdown inhibited the proliferation and growth of hepatocellular carcinoma cells in vitro and in vivo. KPNA2 knockdown also inhibited colony formation ability, induced cell cycle arrest and cellular apoptosis in two hepatocellular carcinoma cell lines, HepG2 and SMMC-7721. Furthermore, gene expression microarray analysis in HepG2 cells with KPNA2 knockdown revealed that critical signaling pathways involved in cell proliferation and survival were deregulated. In conclusion, this study provided systematic evidence that KPNA2 was an essential factor promoting hepatocellular carcinoma and unraveled potential molecular pathways and networks underlying KPNA2-induced hepatocellular carcinogenesis.

Enhanced karyopherin-α2 expression is associated with carcinogenesis in patients with intraductal papillary mucinous neoplasms

BACKGROUND/OBJECTIVES

Intraductal papillary mucinous neoplasms (IPMN) can become malignant. Karyopherin-α2 (KPNA2) plays a central role in nucleocytoplasmic transport and is associated with various types of cancer. The current study examined pancreatic KPNA2 expression in cancer patients and evaluated its association with clinicopathological factors, cancer cell proliferation.

METHODS

KPNA2 expression was investigated by immunohistochemistry in 40 surgically resected IPMN samples and its association with clinicopathological factors and Ki-67 expression were examined.

RESULTS

Eighteen IPMN samples (45% of patients) showed positive KPNA2 expression. KPNA2 expression levels in IPMN tissue with invasive carcinoma were significantly higher than those in adjacent normal tissues and in IPMN tissue with low-to high-grade dysplasia. KPNA2 expression correlated with pathological malignancy and Ki-67 labeling index and KPNA2 and Ki-67 expression was co-localized in nuclei. E2F were co-localized with KPNA2 in the IPMN tissues with high expression of KPNA2. KPNA2 expression was enhanced in the invasion front and in proliferating Ki-67-positive cells. In addition, KPNA2 expression in IPMN tissues was associated with older age, dilation of main pancreatic duct diameter, the presence of nodules, and histological type.

CONCLUSION

KPNA2 expression is associated with carcinogenesis of IPMN through the adenoma-carcinoma sequence.

Analysis of Microarray Data on Gene Expression and Methylation to Identify Long Non-coding RNAs in Non-small Cell Lung Cancer

To identify what long non-coding RNAs (lncRNAs) are involved in non-small cell lung cancer (NSCLC), we analyzed microarray data on gene expression and methylation. Gene expression chip and HumanMethylation450BeadChip were used to interrogate genome-wide expression and methylation in tumor samples. Differential expression and methylation were analyzed through comparing tumors with adjacent non-tumor tissues. LncRNAs expressed differentially and correlated with coding genes and DNA methylation were validated in additional tumor samples using RT-qPCR and pyrosequencing. In vitro experiments were performed to evaluate lncRNA’s effects on tumor cells. We identified 8,500 lncRNAs expressed differentially between tumor and non-tumor tissues, of which 1,504 were correlated with mRNA expression. Two of the lncRNAs, LOC146880 and ENST00000439577, were positively correlated with expression of two cancer-related genes, KPNA2 and RCC2, respectively. High expression of LOC146880 and ENST00000439577 were also associated with poor survival. Analysis of lncRNA expression in relation to DNA methylation showed that LOC146880 expression was down-regulated by DNA methylation in its promoter. Lowering the expression of LOC146880 or ENST00000439577 in tumor cells could inhibit cell proliferation, invasion and migration. Analysis of microarray data on gene expression and methylation allows us to identify two lncRNAs, LOC146880 and ENST00000439577, which may promote the progression of NSCLC.

MIR517C inhibits autophagy and the epithelial-to-mesenchymal (-like) transition phenotype in human glioblastoma through KPNA2-dependent disruption of TP53 nuclear translocation

The epithelial-to-mesenchymal (-like) transition (EMT), a crucial embryonic development program, has been linked to the regulation of glioblastoma (GBM) progression and invasion. Here, we investigated the role of MIR517C/miR-517c, which belongs to the C19MC microRNA cluster identified in our preliminary studies, in the pathogenesis of GBM. We found that MIR517C was associated with improved prognosis in patients with GBM. Furthermore, following treatment with the autophagy inducer temozolomide (TMZ) and low glucose (LG), MIR517C degraded KPNA2 (karyopherin alpha 2 [RAG cohort 1, importin alpha 1]) and subsequently disturbed the nuclear translocation of TP53 in the GBM cell line U87 in vitro. Interestingly, this microRNA could inhibit autophagy and reduce cell migration and infiltration in U87 cells harboring wild-type (WT) TP53, but not in U251 cells harboring mutant (MU) TP53. Moreover, the expression of epithelial markers (i.e., CDH13/T-cadherin and CLDN1 [claudin 1]) increased, while the expression of mesenchymal markers (i.e., CDH2/N-cadherin, SNAI1/Snail, and VIM [vimentin]) decreased, indicating that the EMT status was blocked by MIR517C in U87 cells. Compared with MIR517C overexpression, MIR517C knockdown promoted infiltration of U87 cells to the surrounding structures in nude mice in vivo. The above phenotypic changes were also observed in TP53(+/+) and TP53(-/-) HCT116 colon cancer cells. In summary, our study provided support for a link between autophagy and EMT status in WT TP53 GBM cells and provided evidence for the signaling pathway (MIR517C-KPNA2-cytoplasmic TP53) involved in attenuating autophagy and eliminating the increased migration and invasion during the EMT.

MiR-26b/KPNA2 axis inhibits epithelial ovarian carcinoma proliferation and metastasis through downregulating OCT4

Karyopherin alpha 2 (KPNA2) is a nuclear transport protein upregulated in many cancers. Our previous study has identified KPNA2 overexpression in epithelial ovarian carcinoma (EOC) tissues, which predicts poor prognosis. However, the mechanism of KPNA2 overexpression in EOC remains unclear. This study aimed to examine the role of miRNA in KPNA2 dysregulation. Our results showed that miR-26b was downregulated in EOC samples, and correlated inversely with KPNA2 expression. Low expression of miR-26b was associated with advanced FIGO stage, poor differentiation, higher risk of distant metastasis and recurrence. Downregulation of miR-26b predicted poor disease-free survival and overall survival in EOC patients. KPNA2 was validated as a direct target of miR-26b. Knockdown of KPNA2 or ectopic expression of miR-26b could downregulate OCT4, vimentin and upregulate E-cadherin. Reintroduction of KPNA2 partially abrogated the suppression effect induced by miR-26b. We further verified that miR-26b/KPNA2/OCT4 axis inhibited EOC cell viability, migratory ability and sphere-forming capacity in vitro and in vivo. In conclusion, our results reveal that miR-26b is downregulated in EOC, and directly targets KPNA2. miR-26b/KPNA2 axis suppresses tumor proliferation and metastasis through decreasing OCT4 expression, which is indicative of the important role of miR-26b/KPNA2/OCT4 axis in EOC carcinogenesis and progression.

Importins and exportins as therapeutic targets in cancer

The nuclear transport proteins, importins and exportins (karyopherin-β proteins), may play an important role in cancer by transporting key mediators of oncogenesis across the nuclear membrane in cancer cells. During nucleocytoplasmic transport of tumor suppressor proteins and cell cycle regulators during the processing of these proteins, aberrant cellular growth signaling and inactivation of apoptosis can occur, both critical to growth and development of tumors. Karyopherin-β proteins bind to these cargo proteins and RanGTP for active transport across the nuclear membrane through the nuclear pore complex. Importins and exportins are overexpressed in multiple tumors including melanoma, pancreatic, breast, colon, gastric, prostate, esophageal, lung cancer, and lymphomas. Furthermore, some of the karyopherin-β proteins such as exportin-1 have been implicated in drug resistance in cancer. Importin and exportin inhibitors are being considered as therapeutic targets against cancer and have shown preclinical anticancer activity. Moreover, synergistic activity has been observed with various chemotherapeutic and targeted agents. However, clinical development of the exportin-1 inhibitor leptomycin B was stopped due to adverse events, including vomiting, anorexia, and dehydration. Selinexor, a selective nuclear export inhibitor, is being tested in multiple clinical trials both as a single agent and in combination with chemotherapy. Selinexor has demonstrated clinical activity in multiple cancers, especially acute myelogenous leukemia and multiple myeloma. The roles of other importin and exportin inhibitors still need to be investigated clinically. Targeting the key mediators of nucleocytoplasmic transport in cancer cells represents a novel strategy in cancer intervention with the potential to significantly affect outcomes.

Aptamers that bind specifically to human KPNA2 (importin-α1) and efficiently interfere with nuclear transport

The importin-α family of proteins plays an important role in the eukaryotic importin/exportin nuclear transport system. These proteins recognize a nuclear localization signal (NLS) within cargo proteins and import them into the nucleus through nuclear pores, in a process mediated by importin-β. Recent studies have shown that importin-α proteins specifically recognize the NLS of several cellular factors and viral proteins, thus regulating their movement. Dysregulation of importin-α is a common hallmark of many pathologies including, multiple cancers. In this study, we isolated aptamers 76 and 72, which bind specifically and efficiently to KPNA2, a member of a subfamily of importin-α1. Both of these aptamers bind to KPNA2 with an equilibrium dissociation constant (K_d) of 150 nM and discriminate between KPNA2 and other sub-family members of importin-α, such as KPNA1 and KPNA3. These aptamers specifically interfere with the nuclear transport of cargo proteins mediated by KPNA2 but neither with KPNA1 nor KPNA3, which belongs to other subfamily of importins. These results suggest that the selected aptamers (76 and 72) warrant further study to explore not only their application in cancer diagnosis but also their use as a specific reagent to potentially block KPNA2-dependent nuclear transport of macromolecules across the nuclear membrane.

Karyopherin α2 induces apoptosis in tongue squamous cell carcinoma CAL-27 cells through the p53 pathway

Tumor onset and progression are associated with dysfunction of the nuclear transport machinery at the level of import and export receptors. However, the role of Karyopherin α2 (KPNA2) in human tongue squamous cell carcinoma (TSCC) remains unknown. We assessed the proliferation, apoptosis and migration of TSCC CAL-27 cells using wound healing, Transwell and MTT assays, western blotting, electron microscopy and acridine orange/ethidium bromide staining following knockdown of KPNA2. The results revealed the antiproliferative, proapoptotic and anti-migratory effects of KPNA2 silencing on the TSCC CAL-27 cells. Moreover, the knockdown of KPNA2 proved to be accompanied by the upregulation of active caspase-3, cytochrome c, Bax, Bad and decreased expression of Bcl-2, p-Bad and XIAP. KPNA2 activated the caspase-dependent pathway in the CAL-27 cells with upregulation of p53, p21Cip1/Waf1 and p16INK4a. Thus, the present study demonstrated that p53/p21Cip1/Waf1/p16INK4a may be an important pathway involved in the function of KPNA2 in TSCC CAL-27 cells.

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.

Population analysis of microsatellite genotypes reveals a signature associated with ovarian cancer

Ovarian cancer (OV) ranks fifth in cancer deaths among women, yet there remain few informative biomarkers for this disease. Microsatellites are repetitive genomic regions which we hypothesize could be a source of novel biomarkers for OV and have traditionally been under-appreciated relative to Single Nucleotide Polymorphisms (SNPs). In this study, we explore microsatellite variation as a potential novel source of genomic variation associated with OV. Exomes from 305 OV patient germline samples and 54 tumors, sequenced as part of The Cancer Genome Atlas, were analyzed for microsatellite variation and compared to healthy females sequenced as part of the 1,000 Genomes Project. We identified a subset of 60 microsatellite loci with genotypes that varied significantly between the OV and healthy female populations. Using these loci as a signature set, we classified germline genomes as ‘at risk’ for OV with a sensitivity of 90.1% and a specificity of 87.6%. Cross-analysis with a similar set of breast cancer associated loci identified individuals ‘at risk’ for both diseases. This study revealed a genotype-based microsatellite signature present in the germlines of individuals diagnosed with OV, and provides the basis for a potential novel risk assessment diagnostic for OV and new personal genomics targets in tumors.

Karyopherin alpha 2 is a novel prognostic marker and a potential therapeutic target for colon cancer

Background

Karyopherin alpha 2 (KPNA2), a member of the karyopherin family, plays a vital role in carcinogenesis. Yet its role in colon cancer is poorly characterized. We sought to clarify the clinical significance of its dysregulated expression in human colon tumor specimens.

Methods

We evaluated KPNA2 mRNA and protein expression by real-time polymerase chain reaction and Western blotting in 40 primary colon cancer tissues and paired adjacent normal colon mucosa specimens. KPNA2 protein expression in colon tissue microarray of tumor and normal tissue specimens and lymph node metastasis specimens obtained from 195 colon cancer patients were analyzed immunohistochemically. The effect of KPNA2 knockdown on carcinogenesis potential of human colon cancer cells was determined using Cell Counting Kit-8 (CCK8), colony formation, cell migration, and tumorigenesis in nude mice.

Results

KPNA2 was expressed at higher levels in colon tumors and lymph node metastasis specimens than in normal tissues. Patients with KPNA2-positive tumors were significantly correlated with the American Joint Committee on Cancer (AJCC) stage (p = 0.01), T-classification (p = 0.018), regional lymph node metastasis (p = 0.025), distant metastasis (p = 0.014), and differentiated degree (p = 0.001). KPNA2 was shown to be an independent prognostic indicator of disease-free survival (HR 1.681; 95 % CI: 1.170–2.416; p = 0.005) and overall survival (HR 2.770; 95 % CI: 1.314–5.837; p = 0.007) for patients with colon cancer. Knockdown of KPNA2 expression inhibited colon cancer cell proliferation, colony formation, and migration.

Conclusion

KPNA2 might play an important role in colorectal carcinogenesis and functions as a novel prognostic indicator and a potential therapeutic target for colorectal cancer.

CD146 as an adverse prognostic factor in uterine sarcoma

Background

Uterine sarcoma is an aggressive malignancy with a poor prognosis. This study aimed to determine the expression of CD146, P53, and Ki-67 in uterine sarcoma and to evaluate their prognostic significance.

Methods

We retrospectively analyzed the prognosis and clinicopathologic features of 68 patients with uterine sarcoma. Immunohistochemical analyses of CD146, P53, and Ki-67 were performed in tissue samples collected from these patients and their relationship with prognosis was investigated.

Results

The 5-year overall survival (OS) rate was 46 %. Endometrial stromal sarcoma (ESS) patients had a better prognosis than leiomyosarcoma (LMS) patients, with a 2-year survival rate of 82 %. The membrane and cytoplasm of tumor cells exhibited CD146 overexpression in 8 (32 %) ESS cases, which was less than the 25 (69.4 %) cases observed in LMS and 2 (28.6 %) in MMMT. CD146 overexpression in the membrane and cytoplasm of tumor cells was closely related to lymph node metastasis (P = 0.021) and Ki-67 overexpression (P = 0.0053); there was no significant correlation with age, tumor size, International Federation of Obstetrics and Gynecology stage, or P53 overexpression in LMS.

Conclusions

CD146, P53, and Ki-67 are overexpressed in uterine sarcoma. CD146 expression correlates with lymph node metastasis and is associated with poor OS in LMS; it may be a potential prognostic marker for LMS.

Nuclear Pore Complexes and Nucleocytoplasmic Transport: From Structure to Function to Disease

Nucleocytoplasmic transport is an essential cellular activity and occurs via nuclear pore complexes (NPCs) that reside in the double membrane of the nuclear envelope. Significant progress has been made during the past few years in unravelling the ultrastructural organization of NPCs and their constituents, the nucleoporins, by cryo-electron tomography and X-ray crystallography. Mass spectrometry and genomic approaches have provided deeper insight into the specific regulation and fine tuning of individual nuclear transport pathways. Recent research has also focused on the roles nucleoporins play in health and disease, some of which go beyond nucleocytoplasmic transport. Here we review emerging results aimed at understanding NPC architecture and nucleocytoplasmic transport at the atomic level, elucidating the specific function individual nucleoporins play in nuclear trafficking, and finally lighting up the contribution of nucleoporins and nuclear transport receptors in human diseases, such as cancer and certain genetic disorders.

KPNA2 is a nuclear export protein that contributes to aberrant localisation of key proteins and poor prognosis of breast cancer

Background:

It is recognised that modulations of the nuclear import of macromolecules have a role in changing cellular phenotypes and carcinogenesis. We and others have noticed that aberrant subcellular localisation of DNA damage response (DDR) proteins in breast cancer (BC) is associated with loss-of-function phenotype. This study aims to investigate the biological and clinical significance of the nucleocytoplasmic transport protein karyopherin α-2 (KPNA2), and its role in controlling DDR proteins subcellular localisation in BC.

Methods:

A large (n=1494) and well-characterised series of early-stage invasive BC with a long-term follow-up was assessed for KPNA2 protein by using immunohistochemistry.

Results:

KPNA2 expression was associated with the subcellular localisation of key DDR proteins that showed cytoplasmic expression including BRCA1, RAD51, SMC6L1, γH2AX, BARD1, UBC9, PIAS1 and CHK1. High level of KPNA2 was associated not only with cytoplasmic localisation of these proteins but also with their low/negative nuclear expression. Positive KPNA2 expression was associated with negative oestrogen receptor and triple-negative phenotype. Survival analysis showed that KPNA2 was associated with poor outcome (P<0.0001), but this effect was not independent of other prognostic variables.

Conclusions:

This study provides further evidence for the complexity of DDR mechanism in BC, and that KNPA2 has a role in the aberrant subcellular localisation of DDR proteins with subsequent impaired function.

High expression of KPNA2 defines poor prognosis in patients with upper tract urothelial carcinoma treated with radical nephroureterectomy

BACKGROUND

To analyze the expression of karyopherin alpha 2 (KPNA2) in upper tract urothelial carcinoma (UTUC) and to investigate whether the KPNA2 expression provides additional prognostic information following radical nephroureterectomy (RNU).

METHODS

A tissue microarray (TMA) containing samples from 176 patients with UTUC who underwent RNU at our institute was analyzed for KPNA2 expression using immunohistochemistry. KPNA2 expression in normal urothelial cell line and urothelial carcinoma cell lines was evaluated by western blot analysis. Using RNA interference in vitro, the effects of KPNA2 inhibition on cellular viability, migration and apoptosis were determined.

RESULTS

KPNA2 expression was significantly upregulated in the UTUC samples compared with the adjacent normal urothelial tissues. High KPNA2 immunoreactivity was identified as a predictor of bladder recurrence (hazard ratio [HR]: 2.017, 95% CI 1.13-3.61, p = 0.018), poor disease-free survival (DFS, HR: 2.754, 95% CI 1.68-4.51, p = 0.001) and poor overall survival (OS, HR: 4.480, 95% CI 1.84-10.89, p = 0.001) for patients with UTUC after RNU. Furthermore, high KPNA2 immunoreactivity was independent of the conventional predictive factors in a multivariate analysis. Additional in vitro experiments revealed that KPNA2 expression was higher in urothelial carcinoma cell lines than in normal urothelial cell line. KPNA2 inhibition with a specific siRNA decreased cell viability and migration and increased apoptosis in urothelial carcinoma cell lines.

CONCLUSIONS

KPNA2 is a novel independent prognostic marker for bladder recurrence, DFS and OS of UTUC patients who have undergone RNU. Moreover, these data suggest that KPNA2 may be a promising therapeutic target for UTUC.

Diversification of importin-α isoforms in cellular trafficking and disease states

The human genome encodes seven isoforms of importin α which are grouped into three subfamilies known as α1, α2 and α3. All isoforms share a fundamentally conserved architecture that consists of an N-terminal, autoinhibitory, importin-β-binding (IBB) domain and a C-terminal Arm (Armadillo)-core that associates with nuclear localization signal (NLS) cargoes. Despite striking similarity in amino acid sequence and 3D structure, importin-α isoforms display remarkable substrate specificity in vivo. In the present review, we look at key differences among importin-α isoforms and provide a comprehensive inventory of known viral and cellular cargoes that have been shown to associate preferentially with specific isoforms. We illustrate how the diversification of the adaptor importin α into seven isoforms expands the dynamic range and regulatory control of nucleocytoplasmic transport, offering unexpected opportunities for pharmacological intervention. The emerging view of importin α is that of a key signalling molecule, with isoforms that confer preferential nuclear entry and spatiotemporal specificity on viral and cellular cargoes directly linked to human diseases.

KPNA2 predicts long term survival in patients with anaplastic oligoastrocytomas

The family of karyopherins comprises importins and exportins which are both involved in nucleocytoplasmic shuttling. Increased levels of karyopherin a2/importin 1 (KPNA2) and chromosome region maintenance protein 1/exportin 1 (CRM1) have been associated with poorer prognosis in patients with infiltrative astrocytomas. Isocitrate dehydrogenase 1 gene (IDH1) R132H mutation status was also recently identified as a prognostic factor for malignant gliomas. We evaluated KPNA2 and CRM1, as well as the IDH1 mutation status, as possible novel biomarkers for World Health Organization grade III anaplastic oligoastrocytomas (AOA). We analyzed nuclear expression of KPNA2 by immunohistochemistry in 72 primary anaplastic gliomas (29 AOA, 24 anaplastic astrocytomas, 19 anaplastic oligodendrogliomas). The IDH1 mutation status was also determined in patients with anaplastic astrocytomas and AOA, and AOA patients were additionally evaluated for CRM1 nuclear expression. Long term survivors (LTS; >8 years) with AOA showed lower KPNA2 expression levels compared to non-LTS (p=0.005). KPNA2 expression (⩾ 5% versus <5%, 1-<5%, median) was found to correlate inversely with overall survival (OS) and progression-free survival (PFS) in our overall series as well as in the AOA group (anaplastic gliomas: OS p=0.017; PFS p=0.033; AOA: OS p=0.017, PFS p=0.040). Mutant IDH1-R132H was detected in 69% of the AOA cohort; a combination of KPNA2 low expression and mutant IDH1-R132H was only seen in LTS (p=0.050). No differences between the histological subtypes were observed in terms of KPNA2 expression and IDH1-R132H mutation status. To our knowledge this is the first time it has been shown that KPNA2 expression may have potential as a prognostic biomarker for AOA as well.