Nuclear Export Inhibition for Pancreatic Cancer Therapy

Prognostic and therapeutic significance of XPO1 in T-cell lymphoma

T-cell lymphoma (TCL) is a highly heterogeneous group of invasive non-Hodgkin lymphoma with adverse prognosis and limited treatment options. The relationship between TCL and Exportin-1 (XPO1), a major nuclear export receptor, has not been established yet. We here investigated the prognostic role and therapeutic implication of XPO1 in TCL. We analyzed XPO1 expression in a cohort of 69 TCL tumors and found that XPO1 was over-expressed in 76.8% of TCL and correlated with decreased progression-free survival (PFS) and overall survival (OS). In vitro treatment of TCL cell lines with KPT-8602, the second-generation selective inhibitor of nuclear export (SINE), inhibited XPO1 expression and showed significant anti-proliferative, cell-cycle arrest and pro-apoptotic efficacy. In mechanism, KPT-8602 restored the localization of cytoplasmic FOXO3A, p27, p21, IκBα and PP2A into the nucleus, leading to AKT and NF-κB deactivation. Our data demonstrate for the first time that XPO1 could be an unfavorable prognostic factor for TCL, and provide a rationale for further investigation of the efficacy of KPT-8602 in TCL patients.

Integration of Protein-Protein Interaction Networks and Gene Expression Profiles Helps Detect Pancreatic Adenocarcinoma Candidate Genes

More and more cancer-associated genes (CAGs) are being identified with the development of biological mechanism research. Integrative analysis of protein-protein interaction (PPI) networks and co-expression patterns of these genes can help identify new disease-associated genes and clarify their importance in specific diseases. This study proposed a PPI network and co-expression integration analysis model (PRNet) to integrate PPI networks and gene co-expression patterns to identify potential risk causative genes for pancreatic adenocarcinoma (PAAD). We scored the importance of the candidate genes by constructing a high-confidence co-expression-based edge-weighted PPI network, extracting protein regulatory sub-networks by random walk algorithm, constructing disease-specific networks based on known CAGs, and scoring the genes of the sub-networks with the PageRank algorithm. The results showed that our screened top-ranked genes were more critical in tumours relative to the known CAGs list and significantly differentiated the overall survival of PAAD patients. These results suggest that the PRNet method of ranking cancer-associated genes can identify new disease-associated genes and is more informative than the original CAGs list, which can help investigators to screen potential biomarkers for validation and molecular mechanism exploration.

Identification of Novel Covalent XPO1 Inhibitors Based on a Hybrid Virtual Screening Strategy

Nuclear export protein 1 (XPO1), a member of the nuclear export protein-p (Karyopherin-P) superfamily, regulates the transport of “cargo” proteins. To facilitate this important process, which is essential for cellular homeostasis, XPO1 must first recognize and bind the cargo proteins. To inhibit this process, small molecule inhibitors have been designed that inhibit XPO1 activity through covalent binding. However, the scaffolds for these inhibitors are very limited. While virtual screening may be used to expand the diversity of the XPO1 inhibitor skeleton, enormous computational resources would be required to accomplish this using traditional screening methods. In the present study, we report the development of a hybrid virtual screening workflow and its application in XPO1 covalent inhibitor screening. After screening, several promising XPO1 covalent molecules were obtained. Of these, compound 8 performed well in both tumor cell proliferation assays and a nuclear export inhibition assay. In addition, molecular dynamics simulations were performed to provide information on the mode of interaction of compound 8 with XPO1. This research has identified a promising new scaffold for XPO1 inhibitors, and it demonstrates an effective and resource-saving workflow for identifying new covalent inhibitors.

Selinexor improves the anti-cancer effect of tucidinostat on TP53 wild-type breast cancer

Histone deacetylase (HDAC) is closely related to the initiation and development of breast cancer (BC). Its inhibitor (HDACi) has been used to treat BC, while the efficacy of clinical trials was not reached expectations. HDACi combined with other drugs may be an effective strategy. This study explored the effect of HDACi tucidinostat combined with selinexor, an exportin 1 (XPO1) inhibitor, on ER⁺Her2^- BC cell lines of MCF-7 (wt-TP53), MDA-MB-175 (wt-TP53), MDA-MB-134 (mut-TP53) and T47D (mut-TP53) in vitro and cell derived xenografts (CDX) of MCF-7 in nude mice in vivo. Results showed that both tucidinostat and selinexor showed better inhibitory activities on wt-TP53 BC (MCF-7 and MDA-MB-175) comparing with mut-TP53 BC (MDA-MB-134 and T47D). Tucidinostat combined with selinexor significantly improved the effects of tucidinostat alone on the proliferation and invasion inhibitions and apoptosis promotions of MCF-7 and MDA-MB-175 cells in vitro. It also significantly enhanced the effects of tucidinostat on up-regulating the expression levels of acetyl-p53, nuclear p53, total p53, p21, Bax and Cleaved Caspase-3, and down-regulating the expression levels of Cyclin D1 and Bcl-2 in MCF-7 or MDA-MB-175 cells. Results consistent with in vitro were also obtained in CDX of MCF-7 in vivo. Taken together, we believe that tucidinostat and selinexor are potentially effective drug combinations for the treatment of wt-TP53 BC, and the molecular mechanism may be through enhancing the activity of p53 in the nucleus of BC cells to suppress proliferation and invasion and promote apoptosis.

Targeting of nucleo‑cytoplasmic transport factor exportin 1 in malignancy (Review)

Nuclear pore complexes (NPCs) regulate the entry and exit of molecules from the cell nucleus. Small molecules pass through NPCs by diffusion while large molecules enter and exit the nucleus by karyopherins, which serve as transport factors. Exportin-1 (XPO1) is a protein that is an important member of the karyopherin family and carries macromolecules from the nucleus to the cytoplasm. XPO1 is responsible for nuclear-cytoplasmic transport of protein, ribosomal RNA and certain required mRNAs for ribosomal biogenesis. Furthermore, XPO1-mediated nuclear export is associated with various types of disease, such as cancer, inflammation and viral infection. The key role of XPO1 in carcinogenesis and its potential as a therapeutic target has been demonstrated by previous studies. Clinical use of novel developed generation-specific XPO1 inhibitors and their combination with other agents to block XPO1-mediated nuclear export are a promising new treatment strategy. The aim of the present study was to explain the working mechanism of XPO1 and inhibitors that block XPO1-mediated nuclear export.

Inhibition of XPO-1 Mediated Nuclear Export through the Michael-Acceptor Character of Chalcones

The nuclear export receptor exportin-1 (XPO1, CRM1) mediates the nuclear export of proteins that contain a leucine-rich nuclear export signal (NES) towards the cytoplasm. XPO1 is considered a relevant target in different human diseases, particularly in hematological malignancies, tumor resistance, inflammation, neurodegeneration and viral infections. Thus, its pharmacological inhibition is of significant therapeutic interest. The best inhibitors described so far (leptomycin B and SINE compounds) interact with XPO1 through a covalent interaction with Cys528 located in the NES-binding cleft of XPO1. Based on the well-established feature of chalcone derivatives to react with thiol groups via hetero-Michael addition reactions, we have synthesized two series of chalcones. Their capacity to react with thiol groups was tested by incubation with GSH to afford the hetero-Michael adducts that evolved backwards to the initial chalcone through a retro-Michael reaction, supporting that the covalent interaction with thiols could be reversible. The chalcone derivatives were evaluated in antiproliferative assays against a panel of cancer cell lines and as XPO1 inhibitors, and a good correlation was observed with the results obtained in both assays. Moreover, no inhibition of the cargo export was observed when the two prototype chalcones 9 and 10 were tested against a XPO1-mutated Jurkat cell line (XPO1C528S), highlighting the importance of the Cys at the NES-binding cleft for inhibition. Finally, their interaction at the molecular level at the NES-binding cleft was studied by applying the computational tool CovDock.

Impact of XPO1 mutations on survival outcomes in metastatic non-small cell lung cancer (NSCLC)

BACKGROUND

Nuclear protein transport is essential in guiding the traffic of important proteins and RNAs between the nucleus and cytoplasm. Export of proteins from the nucleus is mostly regulated by Exportin 1 (XPO1). In cancer, XPO1 is almost universally hyperactive and can promote the export of important tumor suppressors to the cytoplasm. Currently, there are no studies evaluating XPO1 amplifications and mutations in NSCLC and the impact on outcomes.

METHODS

Tumor samples were analyzed using next-generation sequencing (NGS) (NextSeq, 592 Genes), immunohistochemistry (IHC), and whole transcriptome sequencing (WTS, NovaSeq) (Caris Life Sciences, Phoenix, AZ). Survival was extracted from insurance claims data and calculated from time of tissue collection to last contact using Kaplan-Meier estimate.

RESULTS

Among 18,218 NSCLC tumors sequenced, 26 harbored XPO1 mutations and 24 had amplifications. XPO1 mutant tumors were more likely to have high TMB (79% vs. 52%, p = 0.007) and less likely to have high PD-L1 (32% vs. 68%, p = 0.03). KRAS co-mutations were seen in 19% (n = 5) and EGFR co-mutations were rare (n = 2). Among the 17,449 NSCLC tumors with clinical data, there were 24 XPO1 mutant. Comparison of survival between XPO1 mutant and WT showed a negative association with a hazard ratio (HR) of 1.932 (95% CI: 1.144-3.264 p = 0.012). XPO1 amplification was not associated with survival.

CONCLUSIONS

XPO1 pathogenic mutations were associated with a poor survival in NSCLC. Although XPO1 mutations are rare in NSCLC, further studies to assess its associations with treatment responses are warranted.

New Insights into the Link between Melanoma and Thyroid Cancer: Role of Nucleocytoplasmic Trafficking

Cancer remains a major public health concern, mainly because of the incompletely understood dynamics of molecular mechanisms for progression and resistance to treatments. The link between melanoma and thyroid cancer (TC) has been noted in numerous patients. Nucleocytoplasmic transport of oncogenes and tumor suppressor proteins is a common mechanism in melanoma and TC that promotes tumorigenesis and tumor aggressiveness. However, this mechanism remains poorly understood. Papillary TC (PTC) patients have a 1.8-fold higher risk for developing cutaneous malignant melanoma than healthy patients. Our group and others showed that patients with melanoma have a 2.15 to 2.3-fold increased risk of being diagnosed with PTC. The BRAF V600E mutation has been reported as a biological marker for aggressiveness and a potential genetic link between malignant melanoma and TC. The main mechanistic factor in the connection between these two cancer types is the alteration of the RAS-RAF-MEK-ERK signaling pathway activation and translocation. The mechanisms of nucleocytoplasmic trafficking associated with RAS, RAF, and Wnt signaling pathways in melanoma and TC are reviewed. In addition, we discuss the roles of tumor suppressor proteins such as p53, p27, forkhead O transcription factors (FOXO), and NF-_KB within the nuclear and cytoplasmic cellular compartments and their association with tumor aggressiveness. A meticulous English-language literature analysis was performed using the PubMed Central database. Search parameters included articles published up to 2021 with keyword search terms melanoma and thyroid cancer, BRAF mutation, and nucleocytoplasmic transport in cancer.

Exportin-T: A Novel Prognostic Predictor and Potential Therapeutic Target for Neuroblastoma

Exportins as the key mediators of nucleocytoplasmic transport have been identified as the controllers of the passage of numerous types of crucial cancer-related proteins. Targeting exportins in cancer cells might represent an emerging strategy in cancer intervention with the potential to affect clinical outcomes. Here, we focused on the prognostic and therapeutic values of Exportin-T (XPOT) in neuroblastoma. The correlation between the expression and prognostic values of XPOT in patients with neuroblastoma was investigated based on both published transcriptome data and our clinical data. Then, decision curve analysis (DCA) was implemented to identify a XPOT risk prediction model. In addition, RNA inference was performed to silence the expression of XPOT to further investigate the specific roles of XPOT in the progression of neuroblastoma in vitro. Overexpression of XPOT mRNA was associated with poor clinical characteristics, such as age at diagnosis more than 18 months, amplification of MYCN, and advanced International Neuroblastoma Staging System (INSS) stage, and XPOT expression was identified as an independent poor prognosis factor for neuroblastoma using Cox proportional hazards model (P < .001). DCA suggested that neuroblastoma patients could benefit from XPOT risk prediction model-guided interventions (status of MYCN  +  INSS stage  +  XPOT). Experimentally, knockdown of XPOT by small interfering RNA inhibited the proliferation and migration in neuroblastoma cells. XPOT is identified as a novel prognostic predictor and potential therapeutic target for neuroblastoma patients. Further investigation should focus on the profound molecular mechanism underlying the tumor inhibition activity of XPOT inhibitors.

Novel 2'-alkoxymethyl substituted klavuzon derivatives as inhibitors of Topo I and CRM1

In this work, 2'-alkoxymethyl substituted klavuzon derivatives were prepared starting from 2-methyl-1-naphthoic acid in eight steps. Anticancer potencies of the synthesized compounds were evaluated by performing MTT cell viability test over cancerous and healthy pancreatic cell lines, along with CRM1 inhibitory properties in HeLa cells by immunostaining and Topo I inhibition properties by supercoiled DNA relaxation assay. Their cytotoxic activities were also presented in hepatocellular carcinoma cells (HuH-7) derived 3D spheroids. Among the tested klavuzon derivatives, isobutoxymethyl substituted klavuzon showed the highest selectivity of cytotoxic activity against pancreatic cancer cell line. They showed potent Topo I inhibition while their CRM1 inhibitory properties somehow diminished compared to 4'-alkylsubstituted klavuzons. The most cytotoxic 2'-methoxymethyl derivative inhibited the growth of the spheroids derived from HuH-7 cell lines and PI staining exhibited time and concentration dependent cell death in 3D spheroids.

Exportin 1 inhibition as antiviral therapy

Coronavirus 2019 (COVID-19; caused by Severe Acute Respiratory Syndrome Coronavirus 2; SARS-CoV-2) is a currently global health problem. Previous studies showed that blocking nucleocytoplasmic transport with exportin 1 (XPO1) inhibitors originally developed as anticancer drugs can quarantine key viral accessory proteins and genomic materials in the nucleus of host cell and reduce virus replication and immunopathogenicity. These observations support the concept of the inhibition of nuclear export as an effective strategy against an array of viruses, including influenza A, B, and SARS-CoV. Clinical studies using the XPO1 inhibitor selinexor as a therapy for COVID-19 infection are in progress.

Directed Evolution of Therapeutic Antibodies Targeting Glycosylation in Cancer

Simple Summary

We generated a platform for designing optimized functional therapeutic antibodies against cancer glycans. The target tumor-associated carbohydrate antigen is commonly expressed in colon and pancreatic cancers. We developed a system for selection of potent antibodies by yeast surface display against this carbohydrate antigen, then showed that elite clones have potent affinity, specificity, cancer cell binding, and therapeutic efficacy. These tools have broad utility for manipulating and engineering antibodies against carbohydrate antigens, and provide major innovative avenues of research in the field of cancer therapy and diagnostics.

Abstract

Glycosylation patterns commonly change in cancer, resulting in expression of tumor-associated carbohydrate antigens (TACA). While promising, currently available anti-glycan antibodies are not useful for clinical cancer therapy. Here, we show that potent anti-glycan antibodies can be engineered to acquire cancer therapeutic efficacy. We designed yeast surface display to generate and select for therapeutic antibodies against the TACA SLe^a (CA19−9) in colon and pancreatic cancers. Elite clones showed increased affinity, better specificity, improved binding of human pancreatic and colon cancer cell lines, and increased complement-dependent therapeutic efficacy. Molecular modeling explained the structural basis for improved antibody functionality at the molecular level. These new tools of directed molecular evolution and selection for effective anti-glycan antibodies, provide insights into the mechanisms of cancer therapy targeting glycosylation, and provide major methodological advances that are likely to open up innovative avenues of research in the field of cancer theranostics.

Prognostic roles of the transcriptional expression of exportins in hepatocellular carcinoma

Aims: A large number of studies have suggested that exportins (XPOs) play a pivotal role in human cancers. In the present study, we analyzed XPO mRNA expression in cancer tissues and explored their prognostic value in hepatocellular carcinoma (HCC).Methods: Transcriptional and survival data related to XPO expression in HCC patients were obtained through the ONCOMINE and UALCAN databases. Survival analysis plots were drawn with Gene Expression Profiling Interactive Analysis (GEPIA). Sequence alteration data for XPOs were obtained from The Cancer Genome Atlas (TCGA) database and c-BioPortal. Gene functional enrichment analyses were performed with Database for Annotation, Visualization and Integrated Discovery (DAVID).Results: Compared with normal liver tissues, significant XPO mRNA overexpression was observed in HCC cancer tissues. There was a trend of higher XPO expression in more advanced clinical stages and lower differentiated pathological grades of HCC. In HCC patients, high expression of XPO1, CSE1L, XPOT, XPO4/5/6 was related to poor overall survival (OS), and XPO1, CSE1L and XPO5/6 were correlated with poor disease-free survival (DFS). The main genetic alterations in XPOs involved mRNA up-regulation, DNA amplification and deletion. General XPO mutations were remarkably associated with worse OS and mostly affected the pathways of RNA transport and oocyte meiosis.Conclusion: High expression of XPOs was associated with a poor prognosis in HCC patients. XPOs may be exploited as good prognostic biomarkers for survival in HCC patients.

New insights into YAP/TAZ nucleo-cytoplasmic shuttling: new cancer therapeutic opportunities?

Yes‐associated protein (YAP) and transcriptional co‐activator with PDZ‐binding motif (TAZ), the main effectors of the Hippo pathway, are emerging as important players in cancer biology and therapy response. The intracellular localization of YAP/TAZ is a key determinant in the regulation of their activity and their roles in signal transduction. This is particularly relevant for cancer: Aberrant nuclear localization of YAP and TAZ has been observed in numerous human cancers and may therefore represent an attractive target for cancer therapy. In this review, we describe the mechanisms that regulate the nucleo‐cytoplasmic shuttling of YAP/TAZ and their implications for cancer, and discuss how the new insights about this process may pave the way for novel therapeutic strategies.

How hsa-miR-495 performed in the tumorigenesis of pancreatic adenocarcinoma by bioinformatics analysis

INTRODUCTION

Pancreatic adenocarcinoma (PAAD) is one of the most fatal cancers in the world for early metastasis, extensive invasion, and poor prognosis with a 5-year survival rate less than 5%. However, the underlying mechanisms are poorly understood. Therefore, it is urgent to explore molecular markers for early diagnosis or therapy target to improve the outcome of PAAD.

METHODS

We retrieved transcriptome data as well as clinical information from patients with PAAD in The Cancer Genome Altas (TCGA) database. Survival time associated microRNAs (miRNAs) and messenger RNAs (mRNAs) were initially identified, followed by enrichment analysis (Gene Ontology [GO] and pathway). The relationship between survival time associated miRNAs-mRNAs was also investigated to discover putative transcriptional control mechanisms of PAAD. Finally, by consulting the literature and retrieving the database, we found that hsa-miR-495 might have played an important role in PAAD.

RESULTS

In total, 146 miRNAs from 378 miRNAs and 580 mRNA from 17 100 mRNA, including 328 risk mRNA and 252 protective mRNA, were found to be associated with the survival time of PAAD. Eight hundred eighty-eight mRNA-miRNA pairs were related to the survival time of PAAD, involving in 755 mRNAs and 35 miRNAs. We chose 13 miRNAs predicted by target gene in the miRanda database for further research. Among these 13 miRNAs, hsa-miR-495 was identified as a good biomarker. Through GO and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, the significantly enriched pathways involved in focal adhesion, Staphylococcus aureus infection, and Intestinal immune network for immunoglobulin A production. And four target genes and 87 pathways of the hsa-miR-495 were enriched in PAAD. Interestingly, we found hsa-miR-495 with a low expression having a poor overall survival and significantly different recurrence rate within 5 years.

CONCLUSION

Hsa-miR-495 and its target genes may serve as a prognostic and predictive marker in PAAD. Further research on the function of the hsa-miR-495 and its target genes in the KEGG pathway may provide references for treatment of PAAD.

Nuclear Envelope Regulation of Oncogenic Processes: Roles in Pancreatic Cancer

Pancreatic cancer is an aggressive and intractable malignancy with high mortality. This is due in part to a high resistance to chemotherapeutics and radiation treatment conferred by diverse regulatory mechanisms. Among these, constituents of the nuclear envelope play a significant role in regulating oncogenesis and pancreatic tumor biology, and this review focuses on three specific components and their roles in cancer. The LINC complex is a nuclear envelope component formed by proteins with SUN and KASH domains that interact in the periplasmic space of the nuclear envelope. These interactions functionally and structurally couple the cytoskeleton to chromatin and facilitates gene regulation informed by cytoplasmic activity. Furthermore, cancer cell invasiveness is impacted by LINC complex biology. The nuclear lamina is adjacent to the inner nuclear membrane of the nuclear envelope and can actively regulate chromatin in addition to providing structural integrity to the nucleus. A disrupted lamina can impart biophysical compromise to nuclear structure and function, as well as form dysfunctional micronuclei that may lead to genomic instability and chromothripsis. In close relationship to the nuclear lamina is the nuclear pore complex, a large megadalton structure that spans both outer and inner membranes of the nuclear envelope. The nuclear pore complex mediates bidirectional nucleocytoplasmic transport and is comprised of specialized proteins called nucleoporins that are overexpressed in many cancers and are diagnostic markers for oncogenesis. Furthermore, recent demonstration of gene regulatory functions for discrete nucleoporins independent of their nuclear trafficking function suggests that these proteins may contribute more to malignant phenotypes beyond serving as biomarkers. The nuclear envelope is thus a complex, intricate regulator of cell signaling, with roles in pancreatic tumorigenesis and general oncogenic transformation.