The Karyopherin proteins, Crm1 and Karyopherin beta1, are overexpressed in cervical cancer and are critical for cancer cell survival and proliferation

Analysis of the effects of importin α1 on the nuclear translocation of IL-1α in HeLa cells

Interleukin-1α (IL-1α), a cytokine released by necrotic cells, causes sterile inflammation. On the other hand, IL-1α is present in the nucleus and also regulates the expression of many proteins. A protein substrate containing a classical nuclear localization signal (cNLS) typically forms a substrate/importin α/β complex, which is subsequently transported to the nucleus. To the best of our knowledge, no study has directly investigated whether IL-1α-which includes cNLS-is imported into the nucleus in an importin α/β-dependent manner. In this study, we noted that all detected importin α subtypes interacted with IL-1α. In HeLa cells, importin α1-mediated nuclear translocation of IL-1α occurred at steady state and was independent of importin β1. Importin α1 not only was engaged in IL-1α nuclear transport but also concurrently functioned as a molecule that regulated IL-1α protein level in the cell. Furthermore, we discussed the underlying mechanism of IL-1α nuclear translocation by importin α1 based on our findings.

Treatment of multiple myeloma with selinexor: a review

Over the last 20 years, breakthroughs in accessible therapies for the treatment of multiple myeloma (MM) have been made. Nevertheless, patients with MM resistant to immunomodulatory drugs, proteasome inhibitors, and anti-CD38 monoclonal antibodies have a very poor outcome. Therefore, it is necessary to explore new drugs for the treatment of MM. This review summarizes the mechanism of action of selinexor, relevant primary clinical trials, and recent developments in both patients with relapsed/refractory myeloma and patients with newly diagnosed myeloma. Selinexor may be useful for the treatment of refractory MM.

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.

Therapeutic targeting of nuclear export and import receptors in cancer and their potential in combination chemotherapy

Systemic modalities are crucial in the management of disseminated malignancies and liquid tumours. However, patient responses and tolerability to treatment are generally poor and those that enter remission often return with refractory disease. Combination therapies provide a methodology to overcome chemoresistance mechanisms and address dose-limiting toxicities. A deeper understanding of tumorigenic processes at the molecular level has brought a targeted therapy approach to the forefront of cancer research, and novel cancer biomarkers are being identified at a rapid rate, with some showing potential therapeutic benefits. The Karyopherin superfamily of proteins is soluble receptors that mediate nucleocytoplasmic shuttling of proteins and RNAs, and recently, nuclear transport receptors have been recognized as novel anticancer targets. Inhibitors against nuclear export have been approved for clinical use against certain cancer types, whereas inhibitors against nuclear import are in preclinical stages of investigation. Mechanistically, targeting nucleocytoplasmic shuttling has shown to abrogate oncogenic signalling and restore tumour suppressor functions through nuclear sequestration of relevant proteins and mRNAs. Hence, nuclear transport inhibitors display broad spectrum anticancer activity and harbour potential to engage in synergistic interactions with a wide array of cytotoxic agents and other targeted agents. This review is focussed on the most researched nuclear transport receptors in the context of cancer, XPO1 and KPNB1, and highlights how inhibitors targeting these receptors can enhance the therapeutic efficacy of standard of care therapies and novel targeted agents in a combination therapy approach. Furthermore, an updated review on the therapeutic targeting of lesser characterized karyopherin proteins is provided and resistance to clinically approved nuclear export inhibitors is discussed.

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.

CRM1 expression: association with high prognostic value in laryngeal cancer

BACKGROUND

Laryngeal cancer is a very common malignant tumor of the head and neck. While laryngeal cancer does not show any obvious early symptoms, it tends to have a poor prognosis in advanced clinical stages. Chromosome region maintenance 1 (CRM1) mediates the nuclear export of some RNAs, major and tumor suppressor proteins and has been associated with the pathogenesis of many tumors. However, the clinicopathological significance of CRM1 gene expression in laryngeal cancer has not been clarified yet. Therefore, this study aims to detect the expression of CRM1 in laryngeal cancer and to investigate its relationship with clinicopathological parameters and prognosis.

METHODS

CRM1 expression in matched tumor and normal tissues obtained from 43 laryngeal cancer patients were evaluated intracellular for protein and mRNA levels by immunohistochemical staining (IHC), western-blot, and quantitative real-time RT-PCR (qRT-PCR), respectively.

RESULTS

IHC, western-blot, and qRT-PCR analyses showed that CRM1 expression was significantly increased in laryngeal cancer tissue compared to normal tissue. Increased expression of CRM1 has been associated with poor prognostic clinicopathological features, including advanced tumor stage, increased tumor invasion, larger tumor size, positive lymph node metastasis, distant metastasis, and invasive histological type by IHC, western-blot, and qRT-PCR. Kaplan-Meier survival analysis showed that patients with high expression of CRM1 exhibited lower overall survival compared to those with low expression (Log-rank = 7.16, p = 0.007). According to the The Cancer Genome Atlas (TCGA) datasets, elevated CRM1 expression in head and neck cancer including cases of squamous cell laryngeal origin is associated with advanced tumor stage and histological grade (p > 0.05, for all).

DISCUSSION

Consequently, CRM1 plays an important role in laryngeal cancer and may serve as an indicator and prognostic factor for poor overall survival in laryngeal cancer patients.

Proteomic Alteration in the Progression of Multiple Myeloma: A Comprehensive Review

Multiple myeloma (MM) is an incurable hematologic malignancy. Most MM patients are diagnosed at a late stage because the early symptoms of the disease can be uncertain and nonspecific, often resembling other, more common conditions. Additionally, MM patients are commonly associated with rapid relapse and an inevitable refractory phase. MM is characterized by the abnormal proliferation of monoclonal plasma cells in the bone marrow. During the progression of MM, massive genomic alterations occur that target multiple signaling pathways and are accompanied by a multistep process involving differentiation, proliferation, and invasion. Moreover, the transformation of healthy plasma cell biology into genetically heterogeneous MM clones is driven by a variety of post-translational protein modifications (PTMs), which has complicated the discovery of effective treatments. PTMs have been identified as the most promising candidates for biomarker detection, and further research has been recommended to develop promising surrogate markers. Proteomics research has begun in MM, and a comprehensive literature review is available. However, proteomics applications in MM have yet to make significant progress. Exploration of proteomic alterations in MM is worthwhile to improve understanding of the pathophysiology of MM and to search for new treatment targets. Proteomics studies using mass spectrometry (MS) in conjunction with robust bioinformatics tools are an excellent way to learn more about protein changes and modifications during disease progression MM. This article addresses in depth the proteomic changes associated with MM disease transformation.

A general method for quantitative fractionation of mammalian cells

Subcellular fractionation in combination with mass spectrometry-based proteomics is a powerful tool to study localization of key proteins in health and disease. Here we offered a reliable and rapid method for mammalian cell fractionation, tuned for such proteomic analyses. This method proves readily applicable to different cell lines in which all the cellular contents are accounted for, while maintaining nuclear and nuclear envelope integrity. We demonstrated the method's utility by quantifying the effects of a nuclear export inhibitor on nucleoplasmic and cytoplasmic proteomes.

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.

Expression of Karyopherin Alpha 2 and Karyopherin Beta 1 Correlate with Poor Prognosis in Gastric Cancer

INTRODUCTION

Karyopherin alpha 2 (KPNA2) and karyopherin beta 1 (KPNB1) constitute nuclear transport protein complexes involved in nuclear import and are significant in tumor progression. Although high KPNA2 expression was associated with poor prognosis in solid tumors, the relationship between KPNA2 and KPNB1 expression and their prognostic role in gastric cancer (GC) remains unclear.

METHODS

Immunohistochemistry was used to correlate the expression of KPNA2 and KPNB1 with various features, including clinicopathological characteristics in 130 patients with GC and survival in 94 patients with invasive lesions extending to the submucosa or deeper.

RESULTS

High expression of KPNA2 and KPNB1 was found in 25% and 36% of the patients, respectively. Both were significantly related to tumor depth, lymph node metastasis, lymphatic invasion, venous invasion, and Ki-67 expression. KPNA2 expression was significantly related to that of KPNB1 (p < 0.001). Patients with high KPNB1 expression had poorer prognosis than those with low expression (p = 0.027), as was also observed in case of KPNA2 (p < 0.001). Patients with high expression of both KPNA2 and KPNB1 accounted for 18% and had a poorer prognosis than those with high expression of either and those with low expression of both (p = 0.001). Multivariate analysis revealed that high expression of both KPNA2 and KPNB1 was an independent prognostic factor in patients with GC (hazard ratio, 3.46; 95% confidence interval, 1.64-2.73, p = 0.001).

CONCLUSION

KPNA2 expression was correlated with KPNB1 expression, and high co-expression of KPNA2 and KPNB1 may represent a strong prognostic biomarker in GC.

A mass spectrometry-based approach for the identification of Kpnβ1 binding partners in cancer cells

Karyopherin beta 1 (Kpnβ1) is the principal nuclear importer of cargo proteins and plays a role in many cellular processes. Its expression is upregulated in cancer and essential for cancer cell viability, thus the identification of its binding partners might help in the discovery of anti-cancer therapeutic targets and cancer biomarkers. Herein, we applied immunoprecipitation coupled to mass spectrometry (IP-MS) to identify Kpnβ1 binding partners in normal and cancer cells. IP-MS identified 100 potential Kpnβ1 binding partners in non-cancer hTERT-RPE1, 179 in HeLa cervical cancer, 147 in WHCO5 oesophageal cancer and 176 in KYSE30 oesophageal cancer cells, including expected and novel interaction partners. 38 binding proteins were identified in all cell lines, with the majority involved in RNA metabolism. 18 binding proteins were unique to the cancer cells, with many involved in protein translation. Western blot analysis validated the interaction of known and novel binding partners with Kpnβ1 and revealed enriched interactions between Kpnβ1 and select proteins in cancer cells, including proteins involved in cancer development, such as Kpnα2, Ran, CRM1, CCAR1 and FUBP1. Together, this study shows that Kpnβ1 interacts with numerous proteins, and its enhanced interaction with certain proteins in cancer cells likely contributes to the cancer state.

Decreased Expression of Karyopherin-α 1 is Related to the Malignant Degree of Cervical Cancer and is Critical for the Proliferation of Hela Cells

Karyopherin α (KPNA) proteins are involved in nucleocytoplasmic trafficking and are critical for protein subcellular localization. Recent studies have suggested that KPNA proteins are abnormally expressed in various solid tumors. The objective of this study was to investigate the expression of KPNA1 and KPNA2 in cervical cancer tissue with different histologic grades and cell lines, as well as the effects of the KPNA1 expression level on Hela cell proliferation. We collected the medical data of 106 patients with cervical cancer and investigated the protein expression of KPNA1 and KPNA2 by immunohistochemistry and western blot. The results revealed a significantly lower expression of KPNA1 in cervical cancer compared to normal tissue. Conversely, stronger staining intensity for KPNA2 was observed in cervical tumor samples. The expression levels of KPNA1 and KPNA2 were significantly associated with the tumor histologic grade. The weakest KPNA1 expression and strongest staining for KPNA2 were observed in grade III tumor tissue. The expression levels of KPNA1 were lower in Hela and C33A cells compared with normal human cervical epithelial cells; however, the expression of KPNA2 exhibited an opposite trend. The up-regulation of KPNA1 significantly suppressed the proliferation of Hela cells and relevant proteins expression, as well as promoted transportation of IRF3 into nucleus. Our results suggest the downregulation of KPNA1 expression is related to the malignant degree of cervical cancer and is closely associated with the proliferation of cervical cancer cells.

Identification of aberrantly methylated differentially expressed genes and pro-tumorigenic role of KIF2C in melanoma

Background: Skin Cutaneous Melanoma (SKCM) is known as an aggressive malignant cancer, which could be directly derived from melanocytic nevi. However, the molecular mechanisms underlying the malignant transformation of melanocytes and melanoma tumor progression still remain unclear. Increasing research showed significant roles of epigenetic modifications, especially DNA methylation, in melanoma. This study focused on the identification and analysis of methylation-regulated differentially expressed genes (MeDEGs) between melanocytic nevus and malignant melanoma in genome-wide profiles.

Methods: The gene expression profiling datasets (GSE3189 and GSE114445) and gene methylation profiling datasets (GSE86355 and GSE120878) were downloaded from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) and differentially methylated genes (DMGs) were identified via GEO2R. MeDEGs were obtained by integrating the DEGs and DMGs. Then, a functional enrichment analysis of MeDEGs was performed. STRING and Cytoscape were used to describe the protein-protein interaction (PPI) network. Furthermore, survival analysis was implemented to select the prognostic hub genes. Next, we conducted gene set enrichment analysis (GSEA) of hub genes. To validate, SKCM cell culture and lentivirus infection was performed to reveal the expression and behavior pattern of KIF2C. Patients and specimens were collected and then immunohistochemistry (IHC) staining was conducted.

Results: We identified 237 hypomethylated, upregulated genes and 182 hypermethylated, downregulated genes. Hypomethylation-upregulated genes were enriched in biological processes of the oxidation-reduction process, cell proliferation, cell division, phosphorylation, extracellular matrix disassembly and protein sumoylation. Pathway enrichment showed selenocompound metabolism, small cell lung cancer and lysosome. Hypermethylation-downregulated genes were enriched in biological processes of positive regulation of transcription from RNA polymerase II promoter, cell adhesion, cell proliferation, positive regulation of transcription, DNA-templated and angiogenesis. The most significantly enriched pathways involved the transcriptional misregulation in cancer, circadian rhythm, tight junction, protein digestion and absorption and Hippo signaling pathway. After PPI establishment and survival analysis, seven prognostic hub genes were CKS2, DTL, KIF2C, KPNA2, MYBL2, TPX2, and FBL. Moreover, the most involved hallmarks obtained by GSEA were E2F targets, G2M checkpoint and mitotic spindle. Importantly, among the 7 hub genes, we found that down-regulated level of KIF2C expression significantly inhibited the proliferative ability of SKCM cells and suppressed the metastasis capacity of SKCM cells.

Conclusions: Our study identified potential aberrantly methylated-differentially expressed genes participating in the process of malignant transformation from nevus to melanoma tissues based on comprehensive genomic profiles. Transcription profiles of CKS2, DTL, KIF2C, KPNA2, MYBL2, TPX2, and FBL provided clues of aberrantly methylation-based biomarkers, which might improve the development of precision medicine. KIF2C plays a pro-tumorigenic role and potentially inhibited the proliferative ability in SKCM.

KPNB1 modulates the Machado-Joseph disease protein ataxin-3 through activation of the mitochondrial protease CLPP

Machado–Joseph disease (MJD) is characterized by a pathological expansion of the polyglutamine (polyQ) tract within the ataxin-3 protein. Despite its primarily cytoplasmic localization, polyQ-expanded ataxin-3 accumulates in the nucleus and forms intranuclear aggregates in the affected neurons. Due to these histopathological hallmarks, the nucleocytoplasmic transport machinery has garnered attention as an important disease relevant mechanism. Here, we report on MJD cell model-based analysis of the nuclear transport receptor karyopherin subunit beta-1 (KPNB1) and its implications in the molecular pathogenesis of MJD. Although directly interacting with both wild-type and polyQ-expanded ataxin-3, modulating KPNB1 did not alter the intracellular localization of ataxin-3. Instead, overexpression of KPNB1 reduced ataxin-3 protein levels and the aggregate load, thereby improving cell viability. On the other hand, its knockdown and inhibition resulted in the accumulation of soluble and insoluble ataxin-3. Interestingly, the reduction of ataxin-3 was apparently based on protein fragmentation independent of the classical MJD-associated proteolytic pathways. Label-free quantitative proteomics and knockdown experiments identified mitochondrial protease CLPP as a potential mediator of the ataxin-3-degrading effect induced by KPNB1. We confirmed reduction of KPNB1 protein levels in MJD by analyzing two MJD transgenic mouse models and induced pluripotent stem cells (iPSCs) derived from MJD patients. Our results reveal a yet undescribed regulatory function of KPNB1 in controlling the turnover of ataxin-3, thereby highlighting a new potential target of therapeutic value for MJD.

P2RY2-AKT activation is a therapeutically actionable consequence of XPO1 inhibition in acute myeloid leukemia

Selinexor is a first-in-class inhibitor of the nuclear exportin XPO1 that was recently approved by the US Food and Drug Administration for the treatment of multiple myeloma and diffuse large B-cell lymphoma. In relapsed/refractory acute myeloid leukemia (AML), selinexor has shown promising activity, suggesting that selinexor-based combination therapies may have clinical potential. Here, motivated by the hypothesis that selinexor's nuclear sequestration of diverse substrates imposes pleiotropic fitness effects on AML cells, we systematically catalog the pro- and anti-fitness consequences of selinexor treatment. We discover that selinexor activates PI3Kγ-dependent AKT signaling in AML by upregulating the purinergic receptor P2RY2. Inhibiting this axis potentiates the anti-leukemic effects of selinexor in AML cell lines, patient-derived primary cultures and multiple mouse models of AML. In a syngeneic, MLL-AF9-driven mouse model of AML, treatment with selinexor and ipatasertib outperforms both standard-of-care chemotherapy and chemotherapy with selinexor. Together, these findings establish drug-induced P2RY2-AKT signaling as an actionable consequence of XPO1 inhibition in AML.

Obesity affects the proteome profile of periodontal ligament submitted to mechanical forces induced by orthodontic tooth movement in rats

The prevalence of obesity has increased significantly worldwide. Therefore, this study aimed to evaluate the influence of obesity on the proteomic profile of periodontal ligament (PDL) tissues of rat first maxillary molars (1 M) submitted to orthodontic tooth movement (OTM). Ten Holtzman rats were distributed into two groups (n = 5): the M group (OTM), and the OM group (obesity induction plus OTM). Obesity was induced by a high-fat diet for the entire experimental periods After that period, the animals were euthanized and the hemimaxillae removed and processed for laser capture microdissection of the PDL tissues of the 1 M. Peptide extracts were obtained and analyzed by LC-MS/MS. Data are available via ProteomeXchange with identifier PXD033647. Out of the 109 proteins with differential abundance, 49 were identified in the OM group, including Vinculin, Cathepsin D, and Osteopontin, which were selected for in situ localization by immunohistochemistry analysis (IHC). Overall, Gene Ontology (GO) analysis indicated that enriched proteins were related to the GO component cellular category. IHC validated the trends for selected proteins. Our study highlights the differences in the PDL proteome profiling of healthy and obese subjects undergoing OTM. These findings may provide valuable information needed to better understand the mechanisms involved in tissue remodeling in obese patients submitted to orthodontic treatment. SIGNIFICANCE: The prevalence of obesity is increasing worldwide. Emerging findings in the field of dentistry suggest that obesity influences the tissues around the teeth, especially those in the periodontal ligament. Therefore, evaluation of the effect of obesity on periodontal tissues remodeling during orthodontic tooth movement is a relevant research topic. To our knowledge, this is the first study to evaluate proteomic changes in periodontal ligament tissue in response to the association between orthodontic tooth movement and obesity. Our study identified a novel protein profile associated with obesity by using laser microdissection and proteomic analysis, providing new information to increase understanding of the mechanisms involved in obese patients undergoing orthodontic treatment which can lead to a more personalized orthodontic treatment approach.

Venetoclax enhances DNA damage induced by XPO1 inhibitors: A novel mechanism underlying the synergistic antileukaemic effect in acute myeloid leukaemia

Acute myeloid leukaemia (AML) is a highly heterogeneous haematologic malignancy with poor prognosis. We previously showed synergistic antileukaemic interaction between exportin 1 (XPO1) inhibitor KPT-330 (Selinexor) and Bcl-2 inhibitor venetoclax (ABT-199) in preclinical models of AML, which was partially meditated by Mcl-1, although the full mechanism of action remains unknown. In this study, using real-time RT-PCR and Western blot analysis, we show that inhibition of XPO1 via KPT-330 or KPT-8602 (Eltanexor) decreases the mRNA and protein levels of c-Myc, CHK1, WEE1, RAD51 and RRM2. KPT-330 and KPT-8602 induce DNA damage, as determined by alkaline comet assay. In addition, we demonstrate that venetoclax enhances KPT-330- and KPT-8602-induced DNA damage, likely through inhibition of DNA damage repair. This study provides new insight into the molecular mechanism underlying the synergistic antileukaemic activity between venetoclax and XPO1 inhibitors against AML. Our data support the clinical evaluation of this promising combination therapy for the treatment of AML.

Inhibitor of the Nuclear Transport Protein XPO1 Enhances the Anticancer Efficacy of KRAS G12C Inhibitors in Preclinical Models of KRAS G12C-Mutant Cancers

The identification of molecules that can bind covalently to KRAS G12C and lock it in an inactive GDP-bound conformation has opened the door to targeting KRAS G12C selectively. These agents have shown promise in preclinical tumor models and clinical trials. FDA has recently granted approval to sotorasib for KRAS G12C mutated non-small cell lung cancer (NSCLC). However, patients receiving these agents as monotherapy generally develop drug resistance over time. This necessitates the development of multi-targeted approaches that can potentially sensitize tumors to KRAS inhibitors. We generated KRAS G12C inhibitor-resistant cell lines and observed that they exhibit sensitivity toward selinexor, a selective inhibitor of nuclear export protein exportin1 (XPO1), as a single agent. KRAS G12C inhibitors in combination with selinexor suppressed the proliferation of KRAS G12C mutant cancer cell lines in a synergistic manner. Moreover, combined treatment of selinexor with KRAS G12C inhibitors resulted in enhanced spheroid disintegration, reduction in the number and size of colonies formed by G12C mutant cancer cells. Mechanistically, the combination of selinexor with KRAS G12C inhibitors suppressed cell growth signaling and downregulated the expression of cell cycle markers, KRAS and NF-kB as well as increased nuclear accumulation of tumor suppressor protein Rb. In an in vivo KRAS G12C cell-derived xenograft model, oral administration of a combination of selinexor and sotorasib was demonstrated to reduce tumor burden and enhance survival. In conclusion, we have shown that the nuclear transport protein XPO1 inhibitor can enhance the anticancer activity of KRAS G12C inhibitors in preclinical cancer models.

Significance

In this study, combining nuclear transport inhibitor selinexor with KRAS G12C inhibitors has resulted in potent antitumor effects in preclinical cancer models. This can be an effective combination therapy for cancer patients that do not respond or develop resistance to KRAS G12C inhibitor treatment.

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.

Pan-cancer analysis reveals the roles of XPO1 in predicting prognosis and tumorigenesis

Background

Exportin 1 (XPO1), a nuclear export protein, participates in many biological processes, including mRNA transport, nucleocytoplasmic transport, nuclear protein export, regulation of mRNA stability, and drug response. XPO1 plays key roles in many cancer types and may serve as a potential biomarker. It is significant to systematically elucidate the roles of XPO1 in various cancer types in terms of function, molecular biology, immunology, and clinical relevance.

Methods

Data from UCSC Xena, CCLE, and CBioPortal were analyzed for the investigation of the differential expression of XPO1 across multiple cancer types. Clinical data were acquired to analyze the influence of XPO1 on the clinical characteristics of patients, such as survival outcome and clinical stage. The roles of XPO1 in the onset and progression of multiple cancers were expounded in terms of genetic changes at the molecular level [including tumor mutational burden (TMB), microsatellite instability (MSI), copy number variation (CNV), methylation, and gene co-expression], biological pathway changes, and the immune microenvironment.

Results

XPO1 was overexpressed in various tumor types, which may be related to CNV. Clinical data analysis revealed that XPO1 may serve as a risk factor in tumors, such as adrenocortical carcinoma, liver hepatocellular carcinoma, and low-grade glioma, thereby affecting patient prognosis. XPO1 in multiple tumor types was also substantially correlated with clinical stage, patient gender, and patient age. In certain tumors, the expression level of XPO1 exerted a greater influence on TMB and MSI. It was also found that XPO1 inhibited the activity of immune cells in the tumor immune microenvironment, such as CD8+ T cells, and affected biological pathways, such as the cell cycle and oxidative phosphorylation, and drove the expression of cancer driver genes, immune checkpoint genes, and highly mutated genes.

Conclusions

XPO1 is a potential pan-cancer risk factor as it may jointly promote tumor onset and progression by inhibiting the immune response, influencing relevant biological pathways, and promoting mutations in other genes.

Targeting XPO1-Dependent Nuclear Export in Cancer

Nucleocytoplasmic transport of macromolecules is tightly regulated in eukaryotic cells. XPO1 is a transport factor responsible for the nuclear export of several hundred protein and RNA substrates. Elevated levels of XPO1 and recurrent mutations have been reported in multiple cancers and linked to advanced disease stage and poor survival. In recent years, several novel small-molecule inhibitors of XPO1 were developed and extensively tested in preclinical cancer models and eventually in clinical trials. In this brief review, we summarize the functions of XPO1, its role in cancer, and the latest results of clinical trials of XPO1 inhibitors.

Chromosome Region Maintenance 1 (XPO1/CRM1) as an Anticancer Target and Discovery of Its Inhibitor

Chromosome region maintenance 1 (CRM1) is a major nuclear export receptor protein and contributes to cell homeostasis by mediating the transport of cargo from the nucleus to the cytoplasm. CRM1 is a therapeutic target comprised of several tumor types, including osteosarcoma, multiple myeloma, gliomas, and pancreatic cancer. In the past decade, dozens of CRM1 inhibitors have been discovered and developed, including KPT-330, which received FDA approval for multiple myeloma (MM) and diffuse large B-cell lymphoma (DLBCL) in 2019 and 2020, respectively. This review summarizes the biological functions of CRM1, the current understanding of the role CRM1 plays in cancer, the discovery of CRM1 small-molecule inhibitors, preclinical and clinical studies on KPT-330, and other recently developed inhibitors. A new CRM1 inhibition mechanism and structural dynamics are discussed. Through this review, we hope to guide the future design and optimization of CRM1 inhibitors.

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.

Selinexor and the Selective Inhibition of Nuclear Export: A New Perspective on the Treatment of Sarcomas and Other Solid and Non-Solid Tumors

Nucleocytoplasmic transport has been found dysregulated in many types of cancer and is often described as a poor prognostic factor. Specifically, Exportin-1 (XPO1) has been found overexpressed in many tumors and has become an attractive target in molecular oncology and therapeutics development. The selective inhibitor of nuclear export, Selinexor, is one of the most scientifically interesting drugs that targets XPO1 in clinical development. In this review, we summarized the most relevant preclinical and clinical results achieved for non-solid tumors, sarcomas, and other kind of solid tumors.

Measuring and Interpreting Nuclear Transport in Neurodegenerative Disease-The Example of C9orf72 ALS

Transport from and into the nucleus is essential to all eukaryotic life and occurs through the nuclear pore complex (NPC). There are a multitude of data supporting a role for nuclear transport in neurodegenerative diseases, but actual transport assays in disease models have provided diverse outcomes. In this review, we summarize how nuclear transport works, which transport assays are available, and what matters complicate the interpretation of their results. Taking a specific type of ALS caused by mutations in C9orf72 as an example, we illustrate these complications, and discuss how the current data do not firmly answer whether the kinetics of nucleocytoplasmic transport are altered. Answering this open question has far-reaching implications, because a positive answer would imply that widespread mislocalization of proteins occurs, far beyond the reported mislocalization of transport reporters, and specific proteins such as FUS, or TDP43, and thus presents a challenge for future research.

Combining selective inhibitors of nuclear export (SINEs) with chimeric antigen receptor (CAR) T cells for CD19‑positive malignancies

Chimeric antigen receptor (CAR) T cells directed against CD19 (CD19.CAR T cells) have yielded impressive clinical responses in the treatment of patients with lymphoid malignancies. However, resistance and/or relapse can limit treatment outcome. Risk of tumor escape can be reduced by combining treatment strategies. Selective inhibitors of nuclear export (SINEs) directed against nuclear exportin‑1 (XPO1) have demonstrated anti‑tumor efficacy in several hematological malignancies. The aim of the present study was to evaluate the combination of CAR T cells with the SINE compounds eltanexor and selinexor. As expected, eltanexor and selinexor were toxic to CD19‑positive malignant cells and the sensitivity of cells towards SINEs correlated with the levels of XPO1‑expression in ALL cell lines. When SINEs and CAR T cells were simultaneously combined, SINEs exerted toxicity towards CAR T cells and impaired their function affecting cytotoxicity and cytokine release ability. Flow cytometry and western blot analysis revealed that eltanexor decreased the cytoplasmic concentration of the transcription factor phosphorylated‑STAT3 in CAR T cells. Due to CAR T‑cell toxicity, sequential use of SINEs and CAR T cells was evaluated: Cytotoxicity of CAR T cells increased significantly when target cells were pre‑treated with the SINE compound eltanexor. In addition, exhaustion of CAR T cells decreased when target cells were pre‑treated with eltanexor. In summary, whereas the concomitant use of SINEs and CAR T cells does not seem advisable, sequential use of SINEs and CAR T cells might improve the anti‑tumor efficacy of CAR T cells.

Selinexor decreases HIF-1α via inhibition of CRM1 in human osteosarcoma and hepatoma cells associated with an increased radiosensitivity

BACKGROUND

The nuclear pore complexes (NPCs) are built of about 30 different nucleoporins and act as key regulators of molecular traffic between the cytoplasm and the nucleus for sizeable proteins (> 40 kDa) which must enter the nucleus. Various nuclear transport receptors are involved in import and export processes of proteins through the nuclear pores. The most prominent nuclear export receptor is chromosome region maintenance 1 (CRM1), also known as exportin 1 (XPO1). One of its cargo proteins is the prolyl hydroxylase 2 (PHD2) which is involved in the initiation of the degradation of hypoxia-inducible factors (HIFs) under normoxia. HIFs are proteins that regulate the cellular adaptation under hypoxic conditions. They are involved in many aspects of cell viability and play an important role in the hypoxic microenvironment of cancer. In cancer, CRM1 is often overexpressed thus being a putative target for the development of new cancer therapies. The newly FDA-approved pharmaceutical Selinexor (KPT-330) selectively inhibits nuclear export via CRM1 and is currently tested in additional Phase-III clinical trials. In this study, we investigated the effect of CRM1 inhibition on the subcellular localization of HIF-1α and radiosensitivity.

METHODS

Human hepatoma cells Hep3B and human osteosarcoma cells U2OS were treated with Selinexor. Intranuclear concentration of HIF-1α protein was measured using immunoblot analysis. Furthermore, cells were irradiated with 2-8 Gy after treatment with Selinexor compared to untreated controls.

RESULTS

Selinexor significantly reduced the intranuclear level of HIF-1α protein in human hepatoma cells Hep3B and human osteosarcoma cells U2OS. Moreover, we demonstrated by clonogenic survival assays that Selinexor leads to dose-dependent radiosensitization in Hep3B-hepatoma and U2OS-osteosarcoma cells.

CONCLUSION

Targeting the HIF pathway by Selinexor might be an attractive tool to overcome hypoxia-induced radioresistance.

Bioanalysis of selinexor in mouse plasma micro-samples utilizing UPLC-MS/MS

Selinexor, a first-in-class inhibitor of the nuclear export protein Exportin-1 (XPO1), was recently approved for the treatment of multiple myeloma in combination with dexamethasone, and as monotherapy for diffuse large B-cell lymphoma. To enable investigations of selinexor in mice, we established and validated an ultrahigh-performance liquid chromatography - tandem mass spectrometry (UPLC-MS/MS) assay in the plasma concentration range of 1-1000 ng/mL using plasma microsamples of 5 µL. Protein depletion with acetonitrile was used for efficient isolation of selinexor which was followed by a dilution step, resulting in a scalable sample processing. Quantification was performed with positive electrospray ionization tandem mass spectrometry in the selected reaction monitoring mode. Due to the high sensitivity of the quantification and the scalable sample processing procedure, the assay can be used for different concentration ranges to either further decrease the achievable lower limit of quantification or to reduce the amount of plasma used. The assay showed interday and intraday accuracy of 89.0-109.0% with a corresponding precision ≤ 14.1%. Suitability for investigations of selinexor in small animal experiments was demonstrated by determination of plasma selinexor in mice after oral administration.

Novel small molecule inhibitor of Kpnβ1 induces cell cycle arrest and apoptosis in cancer cells

Karyopherin beta 1 (Kpnβ1) is a major nuclear import receptor that mediates the import of cellular cargoes into the nucleus. Recently it has been shown that Kpnβ1 is highly expressed in several cancers, and its inhibition by siRNA induces apoptotic cancer cell death, while having little effect on non-cancer cells. This study investigated the effect of a novel small molecule, Inhibitor of Nuclear Import-60 (INI-60), on cancer cell biology, as well as nuclear import activities associated with Kpnβ1, and cancer progression in vivo using cervical and oesophageal cancer cell lines. INI-60 treatment resulted in the inhibition of cancer cell proliferation, colony formation, migration and invasion, and induced a G1/S cell cycle arrest, followed by cancer cell death via apoptosis. Non-cancer cells were minimally affected by INI-60 at concentrations that inhibited cancer cells. INI-60 treatment altered the localisation of Kpnβ1 and its cargoes, NFκB/p65, NFAT and AP-1, and the overexpression of Kpnβ1 reduced INI-60 cytotoxicity. INI-60 also inhibited KYSE 30 oesophageal cancer cell line growth in vivo. Taken together, these results show that INI-60 inhibits the nuclear import of Kpnβ1 cargoes and interferes with cancer cell biology. INI-60 presents as a potential therapeutic approach for cancers of different tissue origins and warrants further investigation as a novel anti-cancer agent.

Venetoclax response is enhanced by selective inhibitor of nuclear export compounds in hematologic malignancies

The selective inhibitor of nuclear export (SINE) compounds selinexor (KPT-330) and eltanexor (KPT-8602) are from a novel class of small molecules that target exportin-1 (XPO1 [CRM1]), an essential nucleo-cytoplasmic transport protein responsible for the nuclear export of major tumor suppressor proteins and growth regulators such as p53, p21, and p27. XPO1 also affects the translation of messenger RNAs for critical oncogenes, including MYC, BCL2, MCL1, and BCL6, by blocking the export of the translation initiation factor eIF4E. Early trials with venetoclax (ABT-199), a potent, selective inhibitor of BCL2, have revealed responses across a variety of hematologic malignancies. However, many tumors are not responsive to venetoclax. We used models of acute myeloid leukemia (AML) and diffuse large B-cell lymphoma (DLBCL) to determine in vitro and in vivo responses to treatment with venetoclax and SINE compounds combined. Cotreatment with venetoclax and SINE compounds demonstrated loss of viability in multiple cell lines. Further in vitro analyses showed that this enhanced cell death was the result of an increase in apoptosis that led to a loss of clonogenicity in methylcellulose assays, coinciding with activation of p53 and loss of MCL1. Treatment with SINE compounds and venetoclax combined led to a reduction in tumor growth in both AML and DLBCL xenografts. Immunohistochemical analysis of tissue sections revealed that the reduction in tumor cells was partly the result of an induction of apoptosis. The enhanced effects of this combination were validated in primary AML and DLBCL patient cells. Our studies reveal synergy with SINE compounds and venetoclax in aggressive hematologic malignancies and provide a rationale for pursuing this approach in a clinical trial.

Subcellular Distribution of p53 by the p53-Responsive lncRNA NBAT1 Determines Chemotherapeutic Response in Neuroblastoma

Neuroblastoma has a low mutation rate for the p53 gene. Alternative ways of p53 inactivation have been proposed in neuroblastoma, such as abnormal cytoplasmic accumulation of wild-type p53. However, mechanisms leading to p53 inactivation via cytoplasmic accumulation are not well investigated. Here we show that the neuroblastoma risk-associated locus 6p22.3-derived tumor suppressor NBAT1 is a p53-responsive lncRNA that regulates p53 subcellular levels. Low expression of NBAT1 provided resistance to genotoxic drugs by promoting p53 accumulation in cytoplasm and loss from mitochondrial and nuclear compartments. Depletion of NBAT1 altered CRM1 function and contributed to the loss of p53-dependent nuclear gene expression during genotoxic drug treatment. CRM1 inhibition rescued p53-dependent nuclear functions and sensitized NBAT1-depleted cells to genotoxic drugs. Combined inhibition of CRM1 and MDM2 was even more effective in sensitizing aggressive neuroblastoma cells with p53 cytoplasmic accumulation. Thus, our mechanistic studies uncover an NBAT1-dependent CRM1/MDM2-based potential combination therapy for patients with high-risk neuroblastoma. SIGNIFICANCE: This study shows how a p53-responsive lncRNA mediates chemotherapeutic response by modulating nuclear p53 pathways and identifies a potential treatment strategy for patients with high-risk neuroblastoma.

Inhibition of Kpnβ1 mediated nuclear import enhances cisplatin chemosensitivity in cervical cancer

Background

Inhibition of nuclear import via Karyopherin beta 1 (Kpnβ1) shows potential as an anti-cancer approach. This study investigated the use of nuclear import inhibitor, INI-43, in combination with cisplatin.

Methods

Cervical cancer cells were pre-treated with INI-43 before treatment with cisplatin, and MTT cell viability and apoptosis assays performed. Activity and localisation of p53 and NFκB was determined after co-treatment of cells.

Results

Pre-treatment of cervical cancer cells with INI-43 at sublethal concentrations enhanced cisplatin sensitivity, evident through decreased cell viability and enhanced apoptosis. Kpnβ1 knock-down cells similarly displayed increased sensitivity to cisplatin. Combination index determination using the Chou-Talalay method revealed that INI-43 and cisplatin engaged in synergistic interactions. p53 was found to be involved in the cell death response to combination treatment as its inhibition abolished the enhanced cell death observed. INI-43 pre-treatment resulted in moderately stabilized p53 and induced p53 reporter activity, which translated to increased p21 and decreased Mcl-1 upon cisplatin combination treatment. Furthermore, cisplatin treatment led to nuclear import of NFκB, which was diminished upon pre-treatment with INI-43. NFκB reporter activity and expression of NFκB transcriptional targets, cyclin D1, c-Myc and XIAP, showed decreased levels after combination treatment compared to single cisplatin treatment and this associated with enhanced DNA damage.

Conclusions

Taken together, this study shows that INI-43 pre-treatment significantly enhances cisplatin sensitivity in cervical cancer cells, mediated through stabilization of p53 and decreased nuclear import of NFκB. Hence this study suggests the possible synergistic use of nuclear import inhibition and cisplatin to treat cervical cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-07819-3.

BIRC3 and BIRC5: multi-faceted inhibitors in cancer

BACKGROUND

The evasion from apoptosis is a common strategy adopted by most tumors, and inhibitors of apoptosis proteins (IAPs) are among the most studied molecular and therapeutic targets. BIRC3 (cellular IAP2) and BIRC5 (survivin) are two of the eight members of the human IAPs family. This family is characterized by the presence of the baculoviral IAP repeat (BIR) domains, involved in protein-protein interactions. In addition to the BIR domains, IAPs also contain other important domains like the C-terminal ubiquitin-conjugating (UBC) domain, the caspase recruitment (CARD) domain and the C-terminal Ring zinc-finger (RING) domain.

MAIN BODY

BIRC3 and BIRC5 have been characterized in some solid and hematological tumors and are therapeutic targets for the family of drugs called "Smac mimetics". Many evidences point to the pro-survival and antiapoptotic role of BIRC3 in cancer cells, however, not all the data are consistent and the resulting picture is heterogeneous. For instance, BIRC3 genetic inactivation due to deletions or point mutations is consistently associated to shorter progression free survival and poor prognosis in chronic lymphocytic leukemia patients. BIRC3 inactivation has also been associated to chemoimmunotherapy resistance. On the contrary, the progression from low grade gliomas to high grade gliomas is accompanied by BIRC3 expression increase, which bears relevant prognostic consequences. Due to the relationship between BIRC3, MAP3K14 and the non-canonical NF-kB pathway, BIRC3 inactivation bears consequences also on the tumor cells relying on NF-kB pathway to survive. BIRC5, on the contrary, is commonly considered an anti-apoptotic molecule, promoting cell division and tumor progression and it is widely regarded as potential therapeutic target.

CONCLUSIONS

The present manuscript collects and reviews the most recent literature concerning the role played by BIRC3 and BIRC5 in cancer cells, providing useful information for the choice of the best therapeutic targets.

A phase 1b trial of selinexor, a first-in-class selective inhibitor of nuclear export (SINE), in combination with doxorubicin in patients with advanced soft tissue sarcomas (STS)

BACKGROUND

Selinexor is a first-in-class selective inhibitor of nuclear export (SINE) compound with single-agent activity in soft tissue sarcoma (STS). The study's aim was to determine the safety and efficacy of selinexor in combination with doxorubicin in patients with locally advanced/metastatic STS.

METHODS

This phase 1b study used a mTPI design. Patients received selinexor at either 60 or 80 mg weekly PO plus doxorubicin (75 mg/m² IV q21 days). Patients with clinical benefit (defined as ≥stable disease via RECIST 1.1) after six cycles of combination treatment received maintenance selinexor until disease progression or unacceptable toxicity. Disease assessments were conducted every two cycles. Pharmacokinetic data were collected on the first three patients per dose level.

RESULTS

Twenty-five patients were enrolled (20 female, ECOG 0/1: 13/12, median age 57 years [range 21-74]). Disease subtypes included leiomyosarcoma (n = 6), malignant peripheral nerve sheath tumour (n = 3) and other sarcomas (n = 16). Three (12%) and 22 (88%) patients were treated at 60 mg and 80 mg of selinexor, respectively. The most common ≥G3 drug-related adverse events (AEs) were haematological, including neutropenia (56%), febrile neutropenia (28%) and anaemia (24%). There were four dose-limiting toxicities (febrile neutropenia (x2), vomiting, fatigue) all at the 80 mg dose level. There was one death secondary to heart failure. Of the 24 evaluable patients, 5 (21%) had a partial response and 15 (63%) had SD as best response. The estimated median progression-free survival (PFS) and overall survival (OS) were 5.5 (95% CI:4.1-5.7) and 10.5 (95% CI:7.5-14) months.

CONCLUSION

In a heterogeneous group of patients with locally advanced/metastatic STS, the combination of selinexor and doxorubicin fulfilled the prespecified boundary for tolerability.

A phase I open-label study of selinexor with paclitaxel and carboplatin in patients with advanced ovarian or endometrial cancers

PURPOSE

Selinexor, a selective inhibitor of nuclear export, monotherapy causes nuclear accumulation of tumor-suppressor proteins and has anti-tumor activity in ovarian and endometrial cancers. The safety and tolerability of oral selinexor plus intravenous carboplatin and paclitaxel chemotherapy (selinexor + CP) was evaluated in this population.

PATIENTS AND METHODS

This phase I, 3 + 3 dose-escalation study assessed 4 selinexor + CP regimens. Patients in cohorts of 3, regardless of disease type, were administered 1 of 4 alternating regimens (selinexor at 30 mg/m2 or 60 mg plus CP at AUC 5 and 175 mg/m2 or 80 mg/m2, respectively) for 6-10 cycles (1 cycle = 21 days), followed by selinexor maintenance. Enrolled patients with ovarian cancer had received 1 prior platinum-based therapy. Patients with endometrial cancer were chemotherapy-naive or had received 1 prior platinum-based therapy. Response was evaluated every 9 weeks.

RESULTS

Twenty-three patients were treated (5 serous ovarian cancer; 18 endometrial cancer, including 6 carcinosarcomas). The most common treatment-related adverse events (TRAEs) were thrombocytopenia (100%), leukopenia (91%), and hyperglycemia (87%). The most common grade 3/4 TRAEs were leukopenia (70%), neutropenia (70%), lymphopenia (61%), anemia (57%), and alanine transaminase increase (43%). One treatment-related dose-limiting toxicity (grade 3 syncope) occurred. Twelve patients achieved a partial response and 1 achieved a complete response. Responses to all four regimens were observed in ovarian and endometrial cancers.

CONCLUSIONS

Combination selinexor + CP was safe and tolerated in advanced ovarian and endometrial cancers.

A Nobel-Winning Scientist: Aziz Sancar and the Impact of his Work on the Molecular Pathology of Neoplastic Diseases

Aziz Sancar, Nobel Prize winning Turkish scientist, made several discoveries which had a major impact on molecular sciences, particularly disciplines that focus on carcinogenesis and cancer treatment, including molecular pathology. Cloning the photolyase gene, which was the initial step of his work on DNA repair mechanisms, discovery of the "Maxicell" method, explanation of the mechanism of nucleotide excision repair and transcription-coupled repair, discovery of "molecular matchmakers", and mapping human excision repair genes at single nucleotide resolution constitute his major research topics. Moreover, Sancar discovered the cryptochromes, the clock genes in humans, in 1998, and this discovery led to substantial progress in the understanding of the circadian clock and the introduction of the concept of "chrono-chemoterapy" for more effective therapy in cancer patients. This review focuses on Aziz Sancar's scientific studies and their reflections on molecular pathology of neoplastic diseases. While providing a new perspective for researchers working in the field of pathology and molecular pathology, this review is also an evidence of how basic sciences and clinical sciences complete each other.

The Nuclear Pore Complex and mRNA Export in Cancer

Export of mRNAs from the nucleus to the cytoplasm is a key regulatory step in the expression of proteins. mRNAs are transported through the nuclear pore complex (NPC). Export of mRNAs responds to a variety of cellular stimuli and stresses. Revelations of the specific effects elicited by NPC components and associated co-factors provides a molecular basis for the export of selected RNAs, independent of bulk mRNA export. Aberrant RNA export has been observed in primary human cancer specimens. These cargo RNAs encode factors involved in nearly all facets of malignancy. Indeed, the NPC components involved in RNA export as well as the RNA export machinery can be found to be dysregulated, mutated, or impacted by chromosomal translocations in cancer. The basic mechanisms associated with RNA export with relation to export machinery and relevant NPC components are described. Therapeutic strategies targeting this machinery in clinical trials is also discussed. These findings firmly position RNA export as a targetable feature of cancer along with transcription and translation.

A novel circular RNA, circXPO1, promotes lung adenocarcinoma progression by interacting with IGF2BP1

Studies have demonstrated that noncoding RNAs play important roles in various types of cancer; however, noncoding RNAs derived from regions of genomic alterations have rarely been explored, especially for circular RNAs (circRNA). Previously, we found several circRNAs were upregulated in lung adenocarcinoma (LUAD) tumor tissues by RNA sequencing. Here, we characterized a novel circRNA, circXPO1, in LUAD, which is derived from a well-established cancer therapeutic target, XPO1. circXPO1, is formed by back-splicing of exon 3 and exon 4 of XPO1 gene. circXPO1 was highly expressed in LUAD tissues compared with paired adjacent non-tumor tissues, and high circXPO1 expression correlated with worse overall survival. circXPO1 expression was positively correlated with the XPO1 gene copy number. Mechanically, circXPO1 could bind with IGF2BP1 and enhance CTNNB1 mRNA stability, and subsequently promote LUAD progression. In a LUAD patient-derived xenograft model, intratumoural injection of cholesterol-conjugated siRNA specifically targeting circXPO1 efficiently suppressed tumor growth. To summary, these results suggest that circXPO1 is critical for LUAD progression and may serve as a biomarker for poor prognosis and a therapeutic target. On the other hand, the functional roles of noncoding transcripts derived from coding genes should be re-evaluated.

Importin β1 regulates cell growth and survival during adult T cell leukemia/lymphoma therapy

There is no cure for adult T cell leukemia/lymphoma (ATLL) associated with human T cell leukemia virus type 1 (HTLV-1), and novel targeted strategies are needed. NF-κB and AP-1 are crucial for ATLL, and both are transported to the nucleus by an importin (IPO)α/β heterodimeric complex to activate target genes. In this study, we aimed to elucidate the function of IPOβ1 in ATLL. The expression of IPOβ1 was analyzed by western blotting and RT-PCR. Cell growth, viability, cell cycle, apoptosis and intracellular signaling cascades were examined by the water-soluble tetrazolium-8 assay, flow cytometry and western blotting. Xenograft tumors in severe combined immune deficient mice were used to evaluate the growth of ATLL cells in vivo. IPOβ1 was upregulated in HTLV-1-infected T cell lines. Further, IPOβ1 knockdown or the IPOβ1 inhibitor importazole and the IPOα/β1 inhibitor ivermectin reduced HTLV-1-infected T cell proliferation. However, the effect of inhibitors on uninfected T cells was less pronounced. Further, in HTLV-1-infected T cell lines, inhibitors suppressed NF-κB and AP-1 nuclear transport and DNA binding, induced apoptosis and poly (ADP-ribose) polymerase cleavage, and activated caspase-3, caspase-8 and caspase-9. Inhibitors also mediated G₁ cell cycle arrest. Moreover, the expression of NF-κB- and AP-1-target proteins involved in cell cycle and apoptosis was reduced. In vivo, the IPOα/β1 inhibitor ivermectin decreased ATLL tumor burden without side effects. IPOβ1 mediated NF-κB and AP-1 translocation into ATLL cell nuclei, thereby regulating cell growth and survival, which provides new insights for targeted ATLL therapies. Thus, ivermectin, an anti-strongyloidiasis medication, could be a potent anti-ATLL agent.

HPV-mediated nuclear export of HP1γ drives cervical tumorigenesis by downregulation of p53

E6 oncoprotein derived from high-risk human papillomavirus (HPV) drives the development of cervical cancer through p53 degradation. Because cervical cancer therapies to inactivate HPV or E6 protein are not available, alternative strategies are required. Here, we show that HPV-mediated nuclear export of human heterochromatin protein 1γ (HP1γ) reduces the stability of p53 through UBE2L3-mediated p53 polyubiquitination during cervical cancer progression. In general, HP1 plays a key role in heterochromatin formation and transcription in the nucleus. However, our immunostaining data showed that the majority of HP1γ is localized in the cytoplasm in HPV-mediated cervical cancer. We found that HPV E6 protein drives unusual nuclear export of HP1γ through the interaction between the NES sequence of HP1γ and exportin-1. The mutation of the NES sequence in HP1γ led to nuclear retention of HP1γ and reduced cervical cancer cell growth and tumor generation. We further discovered that HP1γ directly suppresses the expression of UBE2L3 which drives E6-mediated proteasomal degradation of p53 in cervical cancer. Downregulation of UBE2L3 by overexpression of HP1γ suppressed UBE2L3-dependent p53 degradation-promoting apoptosis of cervical cancer cells. Our findings propose a useful strategy to overcome p53 degradation in cervical cancer through the blockage of nuclear export of HP1γ.

The critical role of germinal center-associated nuclear protein in cell biology, immunohematology, and hematolymphoid oncogenesis

Germinal center-associated nuclear protein (GANP) is a unique and multifunctional protein that plays a critical role in cell biology, neurodegenerative disorders, immunohematology, and oncogenesis. GANP is an orthologue of Saccharomyces Sac3, one of the components of the transcription export 2 (TREX-2) complex and a messenger RNA (mRNA) nuclear export factor. GANP is widely conserved in all mammals, including humans. Although GANP was originally discovered as a molecule upregulated in the germinal centers of secondary lymphoid follicles in peripheral lymphoid organs, it is expressed ubiquitously in many tissues. It serves numerous functions, including making up part of the mammalian TREX-2 complex; mRNA nuclear export via nuclear pores; prevention of R-loop formation, genomic instability, and hyper-recombination; and B-cell affinity maturation. In this review, we first overview the extensive analyses that have revealed the basic functions of GANP and its ancestor molecule Sac3, including mRNA nuclear export and regulation of R-loop formation. We then describe how aberrant expression of GANP is significantly associated with cancer development. Moreover, we discuss a crucial role for GANP in B-cell development, especially affinity maturation in germinal centers. Finally, we illustrate that overexpression of GANP in B cells leads to lymphomagenesis resembling Hodgkin lymphoma derived from germinal center B cells, and that GANP may be involved in transdifferentiation of B cells to macrophages, which strongly affects Hodgkin lymphomagenesis.

HP1γ Sensitizes Cervical Cancer Cells to Cisplatin through the Suppression of UBE2L3

Cisplatin is the most frequently used agent for chemotherapy against cervical cancer. However, recurrent use of cisplatin induces resistance, representing a major hurdle in the treatment of cervical cancer. Our previous study revealed that HP1γ suppresses UBE2L3, an E2 ubiquitin conjugating enzyme, thereby enhancing the stability of tumor suppressor p53 specifically in cervical cancer cells. As a follow-up study of our previous findings, here we have identified that the pharmacological substances, leptomycin B and doxorubicin, can improve the sensitivity of cervical cancer cells to cisplatin inducing HP1γ-mediated elevation of p53. Leptomycin B, which inhibits the nuclear export of HP1γ, increased cisplatin-dependent apoptosis induction by promoting the activation of p53 signaling. We also found that doxorubicin, which induces the DNA damage response, promotes HP1γ-mediated silencing of UBE2L3 and increases p53 stability. These effects resulted from the nuclear translocation and binding of HP1γ on the UBE2L3 promoter. Doxorubicin sensitized the cisplatin-resistant cervical cancer cells, enhancing their p53 levels and rate of apoptosis when administered together with cisplatin. Our findings reveal a therapeutic strategy to target a specific molecular pathway that contributes to p53 degradation for the treatment of patients with cervical cancer, particularly with cisplatin resistance.

NRG1/ERBB3 Pathway Activation Induces Acquired Resistance to XPO1 Inhibitors

XPO1 inhibitors have shown promise in cancer treatment, but mechanisms of resistance to these drugs are not well understood. In this study, we established selective inhibitors of nuclear export (SINE)-resistant ovarian cancer cell lines from in vivo mouse tumors and determined the mechanisms of adaptive XPO1 inhibitor resistance using protein and genomic arrays. Pathway analyses revealed upregulation of the NRG1/ERBB3 pathway in SINE-resistant cells. Depletion of ERBB3 using siRNAs restored the antitumor effect of SINE in vitro and in vivo Furthermore, exogenous NRG1 decreased the antitumor effect of SINE in ovarian cancer cell lines with high ERBB3 expression, but not in those with low expression. These results suggest that NRG1 and ERBB3 expression is a potential biomarker of response to SINE treatment. The antitumor effect of SINE was reduced by exogenous NRG1 in an ERBB3-dependent manner. These findings suggest that NRG1 and ERBB3 are effective biomarkers that should be evaluated in future clinical trials and are relevant therapeutic targets for the treatment of SINE-resistant cancers.

Selinexor in patients with relapsed or refractory diffuse large B-cell lymphoma (SADAL): a single-arm, multinational, multicentre, open-label, phase 2 trial

BACKGROUND

Relapsed or refractory diffuse large B-cell lymphoma (DLBCL) is an aggressive cancer with a median overall survival of less than 6 months. We aimed to assess the response to single-agent selinexor, an oral selective inhibitor of nuclear export, in patients with relapsed or refractory DLBCL who had no therapeutic options of potential clinical benefit.

METHODS

SADAL was a multicentre, multinational, open-label, phase 2b study done in 59 sites in 19 countries. Patients aged 18 years or older with pathologically confirmed diffuse large B-cell lymphoma, an Eastern Cooperative Oncology Group performance status of 2 or less, who had received two to five lines of previous therapies, and progressed after or were not candidates for autologous stem-cell transplantation were enrolled. Germinal centre B-cell or non-germinal centre B-cell tumour subtype and double or triple expressor status were determined by immunohistochemistry and double or triple hit status was determined by cytogenetics. Patients received 60 mg selinexor orally on days 1 and 3 weekly until disease progression or unacceptable toxicity. The study was initially designed to evaluate both 60 mg and 100 mg twice-weekly doses of selinexor; however, the 100 mg dose was discontinued in the protocol (version 7.0) on March 29, 2017, when an improved therapeutic window was observed at 60 mg. Primary outcome was overall response rate. The primary outcome and safety were assessed in all patients who received 60 mg selinexor under protocol version 6.0, or enrolled under protocol versions 7.0 or higher and received at least one dose of selinexor. This trial is registered at ClinicalTrials.gov, NCT02227251 (active but not enrolling).

FINDINGS

Between Oct 21, 2015, and Nov 2, 2019, 267 patients were randomly assigned, with 175 allocated to the 60 mg group and 92 to the discontinued 100 mg group. 48 patients assigned to the 60 mg group were excluded due to enrolment before version 6.0 of the protocol; the remaining 127 patients received selinexor 60 mg and were included in analyses of primary outcome and safety. The overall response rate was 28% (36/127; 95% CI 20·7-37·0); 15 (12%) achieved a complete response and 21 (17%) a partial response. The most common grade 3-4 adverse events were thrombocytopenia (n=58), neutropenia (n=31), anaemia (n=28), fatigue (n=14), hyponatraemia (n=10), and nausea (n=8). The most common serious adverse events were pyrexia (n=9), pneumonia (n=6), and sepsis (n=6). There were no deaths judged as related to treatment with selinexor.

INTERPRETATION

Single-drug oral selinexor induced durable responses and had a manageable adverse events profile in patients with relapsed or refractory DLBCL who received at least two lines of previous chemoimmunotherapy. Selinexor could be considered a new oral, non-cytotoxic treatment option in this setting.

FUNDING

Karyopharm Therapeutics Inc.

Circadian Oscillations Persist in Cervical and Esophageal Cancer Cells Displaying Decreased Expression of Tumor-Suppressing Circadian Clock Genes

There is accumulating evidence for a link between circadian clock disruption and cancer progression. In this study, the circadian clock was investigated in cervical and esophageal cancers, to determine whether it is disrupted in these cancer types. Oncomine datamining revealed downregulation of multiple members of the circadian clock gene family in cancer patient tissue compared with matched normal epithelium. Real-time RT-PCR analysis confirmed significant downregulation of CLOCK, PER1, PER2, PER3, CRY1, CRY2, REV-ERBα, and RORα in esophageal tumor tissue. In cell line models, expression of several circadian clock genes was significantly decreased in transformed and cancer cells compared with noncancer controls, and protein levels were dysregulated. These effects were mediated, at least in part, by methylation, where CLOCK, CRY1, and RORα gene promoter regions were found to be methylated in cancer cells. Overexpression of CLOCK and PER2 in cancer cell lines inhibited cell proliferation and activation of RORα and REV-ERBα using agonists resulted in cancer cell death, while having a lesser effect on normal epithelial cells. Despite dysregulated circadian clock gene expression, cervical and esophageal cancer cells maintain functional circadian oscillations after Dexamethasone synchronization, as revealed using real-time bioluminescence imaging, suggesting that their circadian clock mechanisms are intact. IMPLICATIONS: This study is a first to describe dysregulated, yet oscillating, circadian clock gene expression in cervical and esophageal cancer cells, and knowledge of circadian clock functioning in these cancer types has the potential to inform chronotherapy approaches, where the timing of administration of chemotherapy is optimized on the basis of the circadian clock.

Small Molecule Inhibitors of CRM1

The transport through the nuclear pore complex is used by cancer cells to evade tumor-suppressive mechanisms. Several tumor-suppressors have been shown to be excluded from the cell nucleus in cancer cells by the nuclear export receptor CRM1 and abnormal expression of CRM1 is oncogenic. Inhibition of CRM1 has long been postulated as potential approach for the treatment of cancer and to overcome therapy resistance. Furthermore, the nuclear export of viral components mediated by the CRM1 is crucial in various stages of the viral lifecycle and assembly of many viruses from diverse families, including coronavirus. However, the first nuclear export inhibitors failed or never entered into clinical trials. More recently CRM1 reemerged as a cancer target and a successful proof of concept was achieved with the clinical approval of Selinexor. The chemical complexity of natural products is a promising perspective for the discovery of new nuclear export inhibitors with a favorable toxicity profile. Several screening campaigns have been performed and several natural product-based nuclear export inhibitors have been identified. With this review we give an overview over the role of CRM1-mediated nuclear export in cancer and the effort made to identify and develop nuclear export inhibitors in particular from natural sources.

A long non-coding RNA LINC00461-dependent mechanism underlying breast cancer invasion and migration via the miR-144-3p/KPNA2 axis

Background

The purpose of this study was to explore the regulatory mechanism of the long non-coding RNA (lncRNA) LINC00461 underlying the breast cancer invasion and migration via the miR-144-3p/KPNA2 axis.

Methods

Bioinformatics methods were applied to screen differentially expressed mRNAs, miRNAs and lncRNAs for construction of a competing endogenous RNA (ceRNA) network. LINC00461, KPNA2 and miR-144-3p were identified, and KPNA2 was predicted to be a target of miR-144-3p and significantly correlated with breast cancer prognosis. To make the findings more convincible, we used qRT-PCR to detect the expression levels of LINC00461 and miR-144-3p in breast cancer cells, and conducted western blot to determine KPNA2 protein level. Then, RIP was performed to assess the combination between miR-144-3p and LINC00461 or KPNA2, and dual-luciferase reporter assay was used to validate the targeted relationship between miR-144-3p and KPNA2. Furthermore, Transwell was employed for the examination of cell invasion and migration in breast cancer.

Results

LINC00461 was predicted to regulate KPNA2 through sponging miR-144-3p as revealed by the ceRNA network. Besides, LINC00461 and KPNA2 were found to be remarkably highly-expressed in breast cancer cells, while miR-144-3p was poorly-expressed. Silencing LINC00461 could promote miR-144-3p expression, thus inhibiting cell invasion and migration. In addition, KPNA2 was confirmed to be a direct target of miR-144-3p. Silencing miR-144-3p or overexpressing KPNA2 could reverse the inhibitory effect of LINC00461 silencing on cell invasion and migration in breast cancer.

Conclusion

LINC00461 promoted the expression of KPNA2 by competitively binding to miR-144-3p, thereby promoting the invasion and migration of breast cancer cells.