Nuclear transport and cancer: from mechanism to intervention

UBAP2L ensures homeostasis of nuclear pore complexes at the intact nuclear envelope

Assembly of macromolecular complexes at correct cellular sites is crucial for cell function. Nuclear pore complexes (NPCs) are large cylindrical assemblies with eightfold rotational symmetry, built through hierarchical binding of nucleoporins (Nups) forming distinct subcomplexes. Here, we uncover a role of ubiquitin-associated protein 2-like (UBAP2L) in the assembly and stability of properly organized and functional NPCs at the intact nuclear envelope (NE) in human cells. UBAP2L localizes to the nuclear pores and facilitates the formation of the Y-complex, an essential scaffold component of the NPC, and its localization to the NE. UBAP2L promotes the interaction of the Y-complex with POM121 and Nup153, the critical upstream factors in a well-defined sequential order of Nups assembly onto NE during interphase. Timely localization of the cytoplasmic Nup transport factor fragile X-related protein 1 (FXR1) to the NE and its interaction with the Y-complex are likewise dependent on UBAP2L. Thus, this NPC biogenesis mechanism integrates the cytoplasmic and the nuclear NPC assembly signals and ensures efficient nuclear transport, adaptation to nutrient stress, and cellular proliferative capacity, highlighting the importance of NPC homeostasis at the intact NE.

Targeting colorectal cancer at the level of nuclear pore complex

BACKGROUND

Nuclear pore complexes (NPCs) are the architectures entrenched in nuclear envelop of a cell that regulate the nucleo-cytoplasmic transportation of materials, such as proteins and RNAs for proper functioning of a cell. The appropriate localization of proteins and RNAs within the cell is essential for its normal functionality. For such a complex transportation of materials across the NPC, around 60 proteins are involved comprising nucleoporins, karyopherins and RAN system proteins that play a vital role in NPC's structure formation, cargo translocation across NPC, and cargoes' rapid directed transportation respectively. In various cancers, the structure and function of NPC is often exaggerated, following altered expressions of its nucleoporins and karyopherins, affecting other proteins of associated signaling pathways. Some inhibitors of karyopherins at present, have potential to regulate the altered level/expression of these karyopherin molecules.

AIM OF REVIEW

This review summarizes the data from 1990 to 2023, mainly focusing on recent studies that illustrate the structure and function of NPC, the relationship and mechanisms of nucleoporins and karyopherins with colorectal cancer, as well as therapeutic values, in order to understand the pathology and underlying basis of colorectal cancer associated with NPC. This is the first review to our knowledge elucidating the detailed updated studies targeting colorectal cancer at NPC. The review also aims to target certain karyopherins, Nups and their possible inhibitors and activators molecules as a therapeutic strategy.

KEY SCIENTIFIC CONCEPTS OF REVIEW

NPC structure provides understanding, how nucleoporins and karyopherins as key molecules are responsible for appropriate nucleocytoplasmic transportation. Many studies provide evidences, describing the role of disrupted nucleoporins and karyopherins not only in CRC but also in other non-hematological and hematological malignancies. At present, some inhibitors of karyopherins have therapeutic potential for CRC, however development of more potent inhibitors may provide more effective therapeutic strategies for CRC in near future.

A CRM1-dependent nuclear export signal in Autographa californica multiple nucleopolyhedrovirus Ac93 is important for the formation of intranuclear microvesicles

Autographa californica multiple nucleopolyhedrovirus (AcMNPV) Ac93 is highly conserved in all sequenced baculovirus genomes, and it plays important roles in both the nuclear egress of nucleocapsids and the formation of intranuclear microvesicles. In this study, we characterized a cellular CRM1-dependent nuclear export signal (NES) of AcMNPV Ac93. Bioinformatic analysis revealed that AcMNPV Ac93 may contain an NES at amino acids 115-125. Green fluorescent protein (GFP) fused to the NES (GFP:NES) of AcMNPV Ac93 is localized to the cytoplasm of transfected cells. Multiple point mutation analysis demonstrated that NES is important for the nuclear export of GFP:NES. Bimolecular fluorescence complementation experiments and co-immunoprecipitation assays confirmed that Ac93 interacts with Spodoptera frugiperda CRM1 (SfCRM1). However, AcMNPV Ac34 inhibits cellular CRM1-dependent nuclear export of GFP:NES. To determine whether the NES in AcMNPV Ac93 is important for the formation of intranuclear microvesicles, an ac93-null AcMNPV bacmid was constructed; the wild-type and NES-mutated Ac93 were reinserted into the ac93-null AcMNPV bacmid. Immunofluorescence analysis showed that Ac93 and SfCRM1 were predominantly colocalized at intranuclear microvesicles in infected cells, while the construct containing point mutations at residues 123 and 125 of Ac93 resulted in a defect in budded virus production and the abolishment of intranuclear microvesicles. Together, these data demonstrate that Ac93 contains a functional NES, which is required for the production of progeny viruses and the formation of intranuclear microvesicles.IMPORTANCEAutographa californica multiple nucleopolyhedrovirus (AcMNPV) Ac93 is important for the formation of intranuclear microvesicles. However, how the baculovirus manipulates Ac93 for the formation of intranuclear microvesicles is unclear. In this study, we identified a nuclear export signal (NES) at amino acids 115-125 of AcMNPV Ac93. Our results showed that the NES is required for the interaction between Ac93 and Spodoptera frugiperda CRM1 (SfCRM1). However, AcMNPV Ac34 inhibits the nuclear export of green fluorescent protein fused to the NES. Our analysis revealed that Ac93 and SfCRM1 were predominantly colocalized at intranuclear microvesicles in AcMNPV-infected cells. Together, our results indicate that Ac93 participates in the formation of intranuclear microvesicles via the Ac93 NES-mediated CRM1 pathway.

Targeting RCC1 to block the human soft-tissue sarcoma by disrupting nucleo-cytoplasmic trafficking of Skp2

Soft-tissue sarcomas (STS) emerges as formidable challenges in clinics due to the complex genetic heterogeneity, high rates of local recurrence and metastasis. Exploring specific targets and biomarkers would benefit the prognosis and treatment of STS. Here, we identified RCC1, a guanine-nucleotide exchange factor for Ran, as an oncogene and a potential intervention target in STS. Bioinformatics analysis indicated that RCC1 is highly expressed and correlated with poor prognosis in STS. Functional studies showed that RCC1 knockdown significantly inhibited the cell cycle transition, proliferation and migration of STS cells in vitro, and the growth of STS xenografts in mice. Mechanistically, we identified Skp2 as a downstream target of RCC1 in STS. Loss of RCC1 substantially diminished Skp2 abundance by compromising its protein stability, resulting in the upregulation of p27Kip1 and G1/S transition arrest. Specifically, RCC1 might facilitate the nucleo-cytoplasmic trafficking of Skp2 via direct interaction. As a result, the cytoplasmic retention of Skp2 would further protect it from ubiquitination and degradation. Notably, recovery of Skp2 expression largely reversed the phenotypes induced by RCC1 knockdown in STS cells. Collectively, this study unveils a novel RCC1-Skp2-p27Kip1 axis in STS oncogenesis, which holds promise for improving prognosis and treatment of this formidable malignancy.

E3 ubiquitin ligase RNF180 impairs IPO4/SOX2 complex stability and inhibits SOX2-mediated malignancy in ovarian cancer

RING finger protein 180 (RNF180), an E3 ubiquitin ligase, is thought to be a tumor suppressor gene. However, the detailed mechanism of its effect on ovarian cancer (OV) has not been elucidated. Importin 4 (IPO4) which belongs to transport protein is reported to have cancer-promoting effects on OV. Here, we explored the potential signaling pathways related to RNF180 and IPO4. It was first verified that RNF180 is downregulated and IPO4 is upregulated in OV. By overexpressing or knocking down RNF180 in OV cells, we confirmed that RNF180 inhibited the malignant behaviors of OV cells both in vitro and in vivo. Bioinformatics analysis and proteomics experiments found that RNF180 could interact with IPO4 and promote the degradation of IPO4 through ubiquitination. In addition, overexpression of IPO4 removed the inhibitory effect of RNF180 on OV. We subsequently found that IPO4 could bind to the oncogene Sex determining Region Y-box 2 (SOX2). Knockdown of IPO4 in OV cells decreased SOX2 protein level in nucleus and promoted cyclin-dependent kinase inhibitory protein-1 (p21) expression. Overexpression of RNF180 also inhibited the expression of SOX2 in nucleus. All these results indicated that RNF180 inhibited the nuclear translocation of SOX2 by promoting ubiquitination of IPO4, which ultimately promoted the expression of p21 and then suppressed the progression of OV. This study verified the tumor suppressor effect of RNF180 on OV, elucidated the mechanism of the molecule network related to RNF180 and IPO4 in OV and identified for OV.

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

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

SET-CAN/NUP214 fusion gene in leukemia: general features and clinical advances

SET-CAN/NUP214 fusion is a recurrent event commonly observed in adult male patients diagnosed with T-cell acute lymphoblastic leukemia (T-ALL) and has occasionally been reported in other diseases such as acute myeloid leukemia (AML), myeloid sarcoma (MS), acute undifferentiated leukemia (AUL), chronic myeloid leukemia (CML) and B-cell acute lymphoblastic leukemia (B-ALL). This fusion gene is derived from chromosome del(9)(q34.11;q34.13) or t(9;9)(q34;q34) and may have an inhibitory effect on primitive progenitor differentiation. The prognosis of the reported patients is varied, with these patients often show resistance to chemotherapy regimens that include high doses of glucocorticoids. The optional treatment has not been determined, more cases need to be accumulated and evaluated. The scope of this review is to summarize the general features and prognostic significance in leukemia associated with the SET-CAN/NUP214 fusion gene and to discuss the methods of detection and treatment, aiming at providing some useful references for relevant researchers in the field of blood tumor.

Development and validation of Ran as a prognostic marker in stage I and stage II primary breast cancer

PURPOSE

Existing prognostic biomarkers are inadequate for stratifying breast cancer patients with the highest risk of tumor progression at the time of diagnosis. Here, we demonstrate that the small GTPase Ran has predictive value for breast cancer (BC) patients as a whole, and for specific BC subtypes.

PATIENTS AND METHODS

Ran expression was quantified by immunohistochemistry in 263 patients with primary breast cancer diagnosed at the Breast Unit, Royal Liverpool Hospital. Additionally as an independent validation, we also analyzed the mRNA expressions of Ran, ER, PR, and Cerb-2, the triple-negative endocrine receptors, and their associations with patient survival in a combined patient cohorts of multiple public datasets (n = 1079). We analyzed the data with Spearman's rank correlation and Kaplan-Meier plots coupled with Wilcoxon-Gehan tests, respectively. All statistical tests were two-sided.

RESULTS

Ran nuclear, cytoplasmic, and total staining are substantially associated with poor survival, independent of conventional prognostic markers such as estrogen receptor (ER), human epidermal growth factor receptor 2 (HER2), and lymph node status. According to the datasets, Ran was significantly correlated with distant metastasis-free survival (DMFS) and relapse-free survival (RFS).

CONCLUSION

We found that Ran expression is a unique predictive biomarker for patient survival, metastasis, and tumor relapse. This biomarker could be used for diagnostic purposes, using formalin-fixed, paraffin-embedded tumor biopsy samples from breast cancer patients in the early stages.

Selinexor in Combination with Decitabine Attenuates Ovarian Cancer in Mice

BACKGROUND

High-grade serous ovarian cancer is a lethal gynecologic disease. Conventional therapies, such as platinum-based chemotherapy, are rendered inadequate for disease management as most advanced disease patients develop resistance to this therapy and soon relapse, leading to poor prognosis. Novel immunotherapy and targeted therapy are currently under investigation as treatment options for ovarian cancer, but so far with little success. Epigenetic changes, such as aberrant DNA methylation, have been reported in resistance to platinum-based therapy. Decitabine is a hypomethylating agent which is effective against platinum-resistant disease and also exhibits several anti-tumor immune functions. Selinexor is a selective inhibitor of nuclear protein export. It restored platinum sensitivity in patient-derived ovarian cancer cell lines and is currently in clinical trials for the treatment of platinum-resistant ovarian cancer. We hypothesized that these two agents used in combination could elicit more potent anti-tumor immune responses in vivo than either agent used alone.

METHODS

These studies were designed to investigate the efficacy of these two agents used in combination to treat ovarian cancer by assessing murine models for changes in disease pathology and in anti-tumor responses.

RESULTS

Decitabine priming followed by selinexor treatment significantly limited ascites formation and tumor size. This combination of agents also promoted T cell effector function as measured by granzyme B secretion. Treatment of mice with decitabine and selinexor led to the significant release of a broader range of macrophage and T cell cytokines and chemokines above control PBS and vehicle and above decitabine or selinexor treatment alone.

CONCLUSIONS

These results reveal crucial information for the design of clinical trials which may advance therapy outcomes in ovarian cancer.

Safety, tolerability, and clinical activity of selinexor in combination with pembrolizumab in treatment of metastatic non-small cell lung cancer

BACKGROUND

In lung cancer, overexpression of nuclear export proteins can result in inactivation of critical tumor suppressor proteins and cell-cycle regulators. Selective suppression of nuclear export proteins has immunomodulatory activities. Here, clinical safety and early efficacy data are presented on the combination of pembrolizumab and an oral selective nuclear export inhibitor, selinexor, for the treatment of metastatic non-small cell lung cancer (mNSCLC).

METHODS

The primary objective of this prospective investigator-initiated study was to determine the safety and tolerability of selinexor in combination with pembrolizumab in patients with mNSCLC. Secondary objectives included determination of objective tumor response rate, disease control rate, and progression-free survival duration.

RESULTS

A total of 17 patients were included in the final analysis. Fifteen (88%) received more than two lines of prior systemic therapy and 10 (59%) had prior exposure to anti-PD-1/programmed death-ligand 1 (PD-L1) therapy. The median age was 67.5 years. Ten patients had grade ≥3 adverse events related to selinexor treatment. Responses to treatment occurred in patients who did and did not undergo previous anti-PD-1/PD-L1 therapy and in patients with activating driver mutations. The median overall survival and progression-free survival were 11.4 months (95% CI, 3.4-19.8 months) and 3.0 months (95% CI, 1.7-5.7 months), respectively. The overall response rate was 18% and the 6-month disease control rate was 24%.

CONCLUSIONS

Selinexor in combination with pembrolizumab demonstrated promising antitumor activity in patients with mNSCLC, including those who had previously received anti-PD-1/PD-L1 therapy. The therapy-related toxic effects were consistent with the prior safety data for both drugs, and no overlapping toxic effects were observed.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02419495.

PLAIN LANGUAGE SUMMARY

New strategies to prevent or reverse resistance to immune checkpoint inhibitors are under investigation. Selective inhibitors of nuclear export proteins, such as selinexor, can induce restoration of tumor-suppressing pathways and induce potent immunomodulatory activities. This article contains the clinical safety and early efficacy data on the combination of pembrolizumab and selinexor in treatment of metastatic non-small cell lung cancer.

ACA-28, an anticancer compound, induces Pap1 nuclear accumulation via ROS-dependent and -independent mechanisms in fission yeast

The nucleocytoplasmic transport of proteins is an important mechanism to control cell fate. Pap1 is a fission yeast nucleocytoplasmic shuttling transcription factor of which localization is redox regulated. The nuclear export factor Crm1/exportin negatively regulates Pap1 by exporting it from the nucleus to the cytoplasm. Here, we describe the effect of an anti-cancer compound ACA-28, an improved derivative of 1'-acetoxychavicol acetate (ACA), on the subcellular distribution of Pap1. ACA-28 induced nuclear accumulation of Pap1 more strongly than did ACA. ROS inhibitor N-acetyl-L-cysteine (NAC) partly antagonized the Pap1 nuclear accumulation induced by ACA-28. NAC almost abolished Pap1 nuclear localization upon H 2 O 2 , whereas leptomycin B (LMB)-mediated inhibition of Pap1 nuclear export was resistant to NAC. Collectively, ACA-28-mediated apoptosis in cancer cells may involve ROS-dependent and -independent mechanisms.

The deformation of cancer cells through narrow micropores holds the potential to regulate genes that impact cancer malignancy

Surgery, radiation, hormonal therapy, chemotherapy, and immunotherapy are standard treatment strategies for metastatic breast cancer. However, the heterogeneous nature of the disease poses challenges and continues to make it life-threatening. It is crucial to elucidate further the underlying signaling pathways to improve treatment efficacy. Our study established two triple-negative breast cancer cell lines (TW-1 and TW-2) that were physically deformed using 3 μm pores to investigate the relationship between cancer cell deformation and metastasis within a heterogeneous population. The physical transformation of TW-1 and TW-2 cells significantly affected their growth and migration speed, as evidenced by wound healing assays for collective cell migration and microchannel assays for single-cell migration. We conducted bulk RNA sequencing to gain insights into the genes influenced by physical deformation. Additionally, we evaluated the effects of trametinib resistance on breast cancer cell metastasis by assessing cell viability and migration rates. Interestingly, TW-1 and TW-2 cells exhibited resistance to trametinib treatment. We observed a significant upregulation of GABRA-3, a protein commonly expressed in malignant breast cancer, and the critical transcription factor Myc in TW-1 and TW-2 cells compared to the control group (Ori). However, we did not observe a significant difference in Myc expression between TW-1 and TW-2 cells. In contrast, in the trametinib-resistant cell lines (TW-1-Tra and TW-2-Tra), we found increased expression of OCT4 and SOX2 rather than GABRA-3 or Myc. These findings highlight the differential expression patterns of these genes in our study, suggesting their potential role in cancer cell deformation and drug resistance. Our study presents a potential in vitro model for metastatic and drug-resistant breast cancer cells. By investigating the correlation between cancer cell deformation and metastasis, we contribute to understanding breast cancer heterogeneity and lay the groundwork for developing improved treatment strategies.

[Structural and mechanical plasticity of the nuclear pore]

The nuclear pore, which can be seen as the gateway to the cell nucleus, is central to many processes including gene regulation. It is a complex and dynamic structure composed of more than 30 proteins present in multiple copies that allows the selective and directional transport of RNA and proteins. As shown by recent studies, it is able to adapt its overall structure to the state of the cell. These results suggest that the structural and mechanical plasticity of the nuclear pore is important for its function but also in the development of cancer or viral infections.

Nuclear transport maintenance of USP22-AR by Importin-7 promotes breast cancer progression

The translocation of biological macromolecules between cytoplasm and nucleus is of great significance to maintain various life processes in both normal and cancer cells. Disturbance of transport function likely leads to an unbalanced state between tumor suppressors and tumor-promoting factors. In this study, based on the unbiased analysis of protein expression differences with a mass spectrometer between human breast malignant tumors and benign hyperplastic tissues, we identified that Importin-7, a nuclear transport factor, is highly expressed in breast cancer (BC) and predicts poor outcomes. Further studies showed that Importin-7 promotes cell cycle progression and proliferation. Mechanistically, through co-immunoprecipitation, immunofluorescence, and nuclear-cytoplasmic protein separation experiments, we discovered that AR and USP22 can bind to Importin-7 as cargoes to promote BC progression. In addition, this study provides a rationale for a therapeutic strategy to restream the malignant progression of AR-positive BC by inhibiting the high expression state of Importin-7. Moreover, the knockdown of Importin-7 increased the responsiveness of BC cells to the AR signaling inhibitor, enzalutamide, suggesting that targeting Importin-7 may be a potential therapeutic strategy.

Tat-RAN attenuates brain ischemic injury in hippocampal HT-22 cells and ischemia animal model

Oxidative stress plays a key role in the pathogenesis of neuronal injury, including ischemia. Ras-related nuclear protein (RAN), a member of the Ras superfamily, involves in a variety of biological roles, such as cell division, proliferation, and signal transduction. Although RAN reveals antioxidant effect, its precise neuroprotective mechanisms are still unclear. Therefore, we investigated the effects of RAN on HT-22 cell which were exposed to H₂O₂-induced oxidative stress and ischemia animal model by using the cell permeable Tat-RAN fusion protein. We showed that Tat-RAN transduced into HT-22 cells, and markedly inhibited cell death, DNA fragmentation, and reactive oxygen species (ROS) generation under oxidative stress. This fusion protein also controlled cellular signaling pathways, including mitogen-activated protein kinases (MAPKs), NF-κB, and apoptosis (Caspase-3, p53, Bax and Bcl-2). In the cerebral forebrain ischemia animal model, Tat-RAN significantly inhibited both neuronal cell death, and astrocyte and microglia activation. These results indicate that RAN significantly protects against hippocampal neuronal cell death, suggesting Tat-RAN will help to develop the therapies for neuronal brain diseases including ischemic injury.

Nuclear export of BATF2 enhances colorectal cancer proliferation through binding to CRM1

BACKGROUND

During the tumourigenesis and development of colorectal cancer (CRC), the inactivation of tumour suppressor genes is closely involved, although detailed molecular mechanisms remain elusive. Accumulating studies, including ours, have demonstrated that basic leucine zipper transcription factor ATF (activating transcription factor)-like 2 (BATF2) is a capable tumour suppressor that localises in the nucleus. However, its different subcellular localisation, potential functions and underlying mechanisms are unclear.

METHODS

The translocation of BATF2 and its clinical relevance were detected using CRC samples, cell lines and xenograft nude mice. Candidate BATF2-binding proteins were screened using co-immunoprecipitation, quantitative label-free liquid chromatography-tandem mass spectrometry proteomic analysis, Western blotting and immunofluorescence. Recombinant plasmids, point mutations and siRNAs were applied to clarify the binding sites between BATF2 and chromosome region maintenance 1 (CRM1).

RESULTS

The present study found that BATF2 was mainly localised in the cytoplasm, rather than nucleus, of CRC cells in vitro and in vivo, while cytoplasmic BATF2 expression was inversely correlated with the prognosis of CRC patients. Furthermore, we identified the nuclear export and subsequent ubiquitin-mediated degradation of BATF2 in CRC cells. Mechanistically, a functional nuclear export sequence (any amino acid) was characterised in BATF2 protein, through which BATF2 bound to CRM1 and translocated out of nucleus, ultimately enhancing CRC growth via inducing activator protein 1 (AP-1)/cyclin D1/phosphorylated retinoblastoma protein (pRb) signalling pathway. Additionally, nuclear export of BATF2 can be retarded by the mutation of NES in BATF2 or the knockdown of CRM1, whereas CRM1 expression was negatively associated with nuclear BATF2 expression and the prognosis of CRC patients.

CONCLUSION

These findings revealed the biological effects and underlying mechanisms of cytoplasmic localisation of BATF2. Furthermore, suppressing nuclear export of BATF2 via mutating its NES region or inhibiting CRM1 expression may serve as a promising therapeutic strategy against CRC.

In Response to Precision Medicine: Current Subcellular Targeting Strategies for Cancer Therapy

Emerging as a potent anticancer treatment, subcellular targeted cancer therapy has drawn increasing attention, bringing great opportunities for clinical application. Here, two targeting strategies for four main subcellular organelles (mitochondria, lysosome, endoplasmic reticulum, and nucleus), including molecule- and nanomaterial (inorganic nanoparticles, micelles, organic polymers, and others)-based targeted delivery or therapeutic strategies, are summarized. Phototherapy, chemotherapy, radiotherapy, immunotherapy, and "all-in-one" combination therapy are among the strategies covered in detail. Such materials are constructed based on the specific properties and relevant mechanisms of organelles, enabling the elimination of tumors by inducing dysfunction in the corresponding organelles or destroying specific structures. The challenges faced by organelle-targeting cancer therapies are also summarized. Looking forward, a paradigm for organelle-targeting therapy with enhanced therapeutic efficacy compared to current clinical approaches is envisioned.

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.

TP53 mutations predict poor response to immunotherapy in patients with metastatic solid tumors

BACKGROUND

TP53 is the most commonly mutated gene across all cancer types. R175H mutation was considered structural mutation where the mutation causes misfolding of the protein and leads to a significant conformational alterations within p53's DNA binding domain. The aim of this study was to explain the reason why R175H worse the response to immunotherapy by analyzing tumor immune microenvironment through the expression of immune cells and PD-1.

MATERIALS AND METHODS

Patients diagnosed with metastatic carcinoma, including colorectal cancer (CRC), breast cancer (BRCA), gastric cancer (GC), non-small cell lung cancer (NSCLC), and 20 other cancer types, treated in a palliative setting at Samsung Medical Center between October 2019 and April 2021, were enrolled. Of these patients, those who underwent TDS analysis (TruSight™ Oncology 500 assay [TSO 500]) were finally analyzed.

RESULTS

Of 1770 patients, 1012 (57.2%) harbored genetic alterations in TP53. All mutations were single nucleotide variants (SNVs), and the most frequent SNV was R175H (n = 84, 7.5%) which was known as one of the most common hotspot TP53 mutation. The overall survival of patients with TP53 R175H mutations was significantly worse following chemotherapy (606 vs. 456 days, p < 0.001) or immunotherapy (822 vs. 350 days, p  < 0.001) compared to those with TP53 mutation in other loci. RNA sequencing indicated that the immune response-related pathways were downregulated in tumors harboring TP53 R175H mutation. Moreover, the expression of CD8(+) T cells PD-1 were lowered in R175H mutation tumors. In the analysis of TP53 structural domain, compared to those having TP53 mutation in other domain, patients with mutations occurring in the nuclear exporter signal (NES) and E4F1-binding domains had significantly worse overall survival following chemotherapy (NES: 606 vs. 451 days, p = 0.043; E4F1: 606 vs. 469 days, p = 0.046) and immunotherapy (NES: 822 vs. 403 days, p  < 0.001; E4F1: 822 vs. 413 days, p  < 0.001). In addition, tumors with TP53 mutation and co-existing copy number amplification of CCND1, FGF4, and FGF19 in chromosome 11 conferred worse prognosis than those with only TP53 mutation (p  < 0.050).

DISCUSSION

Each TP53 mutations indicated differential treatment outcomes following chemotherapy or immunotherapy in patients with metastatic cancer. Functional analysis including RNASeq suggested that TP53 mutation downregulated immune response.

CONCLUSION

Overall, we found each TP53 mutation to indicate different prognoses in patients with metastatic tumors undergoing chemotherapy and ICI treatment. Further validations, including a prospective cohort study or a functional study, would be particularly valuable in advancing the knowledge on this aspect and developing improved prognostic parameters.

Protein-protein interaction and interference of carcinogenesis by supramolecular modifications

Protein-protein interactions (PPIs) are essential in normal biological processes, but they can become disrupted or imbalanced in cancer. Various technological advancements have led to an increase in the number of PPI inhibitors, which target hubs in cancer cell's protein networks. However, it remains difficult to develop PPI inhibitors with desired potency and specificity. Supramolecular chemistry has only lately become recognized as a promising method to modify protein activities. In this review, we highlight recent advances in the use of supramolecular modification approaches in cancer therapy. We make special note of efforts to apply supramolecular modifications, such as molecular tweezers, to targeting the nuclear export signal (NES), which can be used to attenuate signaling processes in carcinogenesis. Finally, we discuss the strengths and weaknesses of using supramolecular approaches to targeting PPIs.

ahctf1 and kras mutations combine to amplify oncogenic stress and restrict liver overgrowth in a zebrafish model of hepatocellular carcinoma

The nucleoporin (NUP) ELYS, encoded by AHCTF1, is a large multifunctional protein with essential roles in nuclear pore assembly and mitosis. Using both larval and adult zebrafish models of hepatocellular carcinoma (HCC), in which the expression of an inducible mutant kras transgene (kras^G12V) drives hepatocyte-specific hyperplasia and liver enlargement, we show that reducing ahctf1 gene dosage by 50% markedly decreases liver volume, while non-hyperplastic tissues are unaffected. We demonstrate that in the context of cancer, ahctf1 heterozygosity impairs nuclear pore formation, mitotic spindle assembly, and chromosome segregation, leading to DNA damage and activation of a Tp53-dependent transcriptional programme that induces cell death and cell cycle arrest. Heterozygous expression of both ahctf1 and ranbp2 (encoding a second nucleoporin), or treatment of heterozygous ahctf1 larvae with the nucleocytoplasmic transport inhibitor, Selinexor, completely blocks kras^G12V-driven hepatocyte hyperplasia. Gene expression analysis of patient samples in the liver hepatocellular carcinoma (LIHC) dataset in The Cancer Genome Atlas shows that high expression of one or more of the transcripts encoding the 10 components of the NUP107-160 subcomplex, which includes AHCTF1, is positively correlated with worse overall survival. These results provide a strong and feasible rationale for the development of novel cancer therapeutics that target ELYS function and suggest potential avenues for effective combinatorial treatments.

Differences in genome, transcriptome, miRNAome, and methylome in synchronous and metachronous liver metastasis of colorectal cancer

Despite distant metastases being the critical factor affecting patients' survival, they remain poorly understood. Our study thus aimed to molecularly characterize colorectal cancer liver metastases (CRCLMs) and explore whether molecular profiles differ between Synchronous (SmCRC) and Metachronous (MmCRC) colorectal cancer. This characterization was performed by whole exome sequencing, whole transcriptome, whole methylome, and miRNAome. The most frequent somatic mutations were in APC, SYNE1, TP53, and TTN genes. Among the differently methylated and expressed genes were those involved in cell adhesion, extracellular matrix organization and degradation, neuroactive ligand-receptor interaction. The top up-regulated microRNAs were hsa-miR-135b-3p and -5p, and the hsa-miR-200-family while the hsa-miR-548-family belonged to the top down-regulated. MmCRC patients evinced higher tumor mutational burden, a wider median of duplications and deletions, and a heterogeneous mutational signature than SmCRC. Regarding chronicity, a significant down-regulation of SMOC2 and PPP1R9A genes in SmCRC compared to MmCRC was observed. Two miRNAs were deregulated between SmCRC and MmCRC, hsa-miR-625-3p and has-miR-1269-3p. The combined data identified the IPO5 gene. Regardless of miRNA expression levels, the combined analysis resulted in 107 deregulated genes related to relaxin, estrogen, PI3K-Akt, WNT signaling pathways, and intracellular second messenger signaling. The intersection between our and validation sets confirmed the validity of our results. We have identified genes and pathways that may be considered as actionable targets in CRCLMs. Our data also provide a valuable resource for understanding molecular distinctions between SmCRC and MmCRC. They have the potential to enhance the diagnosis, prognostication, and management of CRCLMs by a molecularly targeted approach.

Bone regeneration strategies based on organelle homeostasis of mesenchymal stem cells

The organelle modulation has emerged as a crucial contributor to the organismal homeostasis. The mesenchymal stem cells (MSCs), with their putative functions in maintaining the regeneration ability of adult tissues, have been identified as a major driver to underlie skeletal health. Bone is a structural and endocrine organ, in which the organelle regulation on mesenchymal stem cells (MSCs) function has most been discovered recently. Furthermore, potential treatments to control bone regeneration are developing using organelle-targeted techniques based on manipulating MSCs osteogenesis. In this review, we summarize the most current understanding of organelle regulation on MSCs in bone homeostasis, and to outline mechanistic insights as well as organelle-targeted approaches for accelerated bone regeneration.

Diagnostic and Prognostic Profiling of Nucleocytoplasmic Shuttling Genes in Hepatocellular Carcinoma

One of the key features of eukaryotic cells is the separation of nuclear and cytoplasmic compartments by a double-layer nuclear envelope. This separation is crucial for timely regulation of gene expression, mRNA biogenesis, cell cycle, and differentiation. Since transcription takes place in the nucleus and the major part of translation in the cytoplasm, proper distribution of biomolecules between these two compartments is ensured by nucleocytoplasmic shuttling proteins - karyopherins. Karyopherins transport biomolecules through nuclear pores bidirectionally in collaboration with Ran GTPases and utilize GTP as the source of energy. Different karyopherins transport different cargo molecules that play important roles in the regulation of cell physiology. In cancer cells, this nucleocytoplasmic transport is significantly dysregulated to support increased demands for the import of cell cycle-promoting biomolecules and export of cell cycle inhibitors and mRNAs. Here, we analysed genomic, transcriptomic and proteomic data from published datasets to comprehensively profile karyopherin genes in hepatocellular carcinoma. We have found out that expression of multiple karyopherin genes is increased in hepatocellular carcinoma in comparison to the normal liver, with importin subunit α-1, exportin 2, importin subunit β-1 and importin 9 being the most over-expressed. More-over, we have found that increased expression of these genes is associated with higher neoplasm grade as well as significantly worse overall survival of liver cancer patients. Taken together, our bioinformatic data-mining analysis provides a comprehensive geno-mic and transcriptomic landscape of karyopherins in hepatocellular carcinoma and identifies potential members that could be targeted in order to develop new treatment regimens.

A-type lamins involvement in transport and implications in cancer?

Nuclear lamins and transport are intrinsically linked, but their relationship is yet to be fully unraveled. A multitude of complex, coupled interactions between lamins and nucleoporins (Nups), which mediate active transport into and out of the nucleus, combined with well documented dysregulation of lamins in many cancers, suggests that lamins and nuclear transport may play a pivotal role in carcinogenesis and the preservation of cancer. Changes of function related to lamin/Nup activity can principally lead to DNA damage, further increasing the genetic diversity within a tumor, which could lead to the reduction the effectiveness of antineoplastic treatments. This review discusses and synthesizes different connections of lamins to nuclear transport and offers a number of outlook questions, the answers to which could reveal a new perspective on the connection of lamins to molecular transport of cancer therapeutics, in addition to their established role in nuclear mechanics.

In Situ Visualization of Epidermal Growth Factor Receptor Nuclear Translocation with Circular Bivalent Aptamer

Epidermal growth factor receptor (EGFR) nuclear translocation correlates with the abnormal proliferation, migration, and anti-apoptosis of tumor cells. Monitoring EGFR nuclear translocation provides insights into the molecular mechanisms underlying cancers. EGFR nuclear translocation includes two processes, EGFR phosphorylation and phosphorylated EGFR translocation to the nucleus. With the help of aptamers, probes that can achieve the first step of anchoring phosphorylated EGFR have been developed. However, the EGFR nuclear translocation can last for hours, posing a challenge to monitor the entire nuclear translocation in living cells. Herein, we designed a circular bivalent aptamer-functionalized optical probe with greatly enhanced stability for long-term visualization of EGFR nuclear translocation in situ. The results of cell experiments show that the probe could monitor the entire nuclear translocation of EGFR. The findings of tissue and in vivo experiments demonstrate that the probe can evaluate the development and progression of tumors by imaging EGFR nuclear translocation in situ. The proposed approach allows us to monitor EGFR nuclear translocation in the long term, indicating its great potential in investigating the mechanisms of cancers and guiding for tumor treatment.

Semi-Supervised Non-Parametric Bayesian Modelling of Spatial Proteomics

Understanding sub-cellular protein localisation is an essential component in the analysis of context specific protein function. Recent advances in quantitative mass-spectrometry (MS) have led to high resolution mapping of thousands of proteins to sub-cellular locations within the cell. Novel modelling considerations to capture the complex nature of these data are thus necessary. We approach analysis of spatial proteomics data in a non-parametric Bayesian framework, using K-component mixtures of Gaussian process regression models. The Gaussian process regression model accounts for correlation structure within a sub-cellular niche, with each mixture component capturing the distinct correlation structure observed within each niche. The availability of marker proteins (i.e. proteins with a priori known labelled locations) motivates a semi-supervised learning approach to inform the Gaussian process hyperparameters. We moreover provide an efficient Hamiltonian-within-Gibbs sampler for our model. Furthermore, we reduce the computational burden associated with inversion of covariance matrices by exploiting the structure in the covariance matrix. A tensor decomposition of our covariance matrices allows extended Trench and Durbin algorithms to be applied to reduce the computational complexity of inversion and hence accelerate computation. We provide detailed case-studies on Drosophila embryos and mouse pluripotent embryonic stem cells to illustrate the benefit of semi-supervised functional Bayesian modelling of the data.

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

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

Inferring differential subcellular localisation in comparative spatial proteomics using BANDLE

The steady-state localisation of proteins provides vital insight into their function. These localisations are context specific with proteins translocating between different subcellular niches upon perturbation of the subcellular environment. Differential localisation, that is a change in the steady-state subcellular location of a protein, provides a step towards mechanistic insight of subcellular protein dynamics. High-accuracy high-throughput mass spectrometry-based methods now exist to map the steady-state localisation and re-localisation of proteins. Here, we describe a principled Bayesian approach, BANDLE, that uses these data to compute the probability that a protein differentially localises upon cellular perturbation. Extensive simulation studies demonstrate that BANDLE reduces the number of both type I and type II errors compared to existing approaches. Application of BANDLE to several datasets recovers well-studied translocations. In an application to cytomegalovirus infection, we obtain insights into the rewiring of the host proteome. Integration of other high-throughput datasets allows us to provide the functional context of these data.

The efficacy of selinexor (KPT-330), an XPO1 inhibitor, on non-hematologic cancers: a comprehensive review

PURPOSE

Selinexor is a novel XPO1 inhibitor which inhibits the export of tumor suppressor proteins and oncoprotein mRNAs, leading to cell-cycle arrest and apoptosis in cancer cells. While selinexor is currently FDA approved to treat multiple myeloma, compelling preclinical and early clinical studies reveal selinexor's efficacy in treating hematologic and non-hematologic malignancies, including sarcoma, gastric, bladder, prostate, breast, ovarian, skin, lung, and brain cancers. Current reviews of selinexor primarily highlight its use in hematologic malignancies; however, this review seeks to summarize the recent evidence of selinexor treatment in solid tumors.

METHODS

Pertinent literature searches in PubMed and the Karyopharm Therapeutics website for selinexor and non-hematologic malignancies preclinical and clinical trials.

RESULTS

This review provides evidence that selinexor is a promising agent used alone or in combination with other anticancer medications in non-hematologic malignancies.

CONCLUSION

Further clinical investigation of selinexor treatment for solid malignancies is warranted.

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.

The importin beta superfamily member RanBP17 exhibits a role in cell proliferation and is associated with improved survival of patients with HPV+ HNSCC

Background

More than twenty years after its discovery, the role of the importin beta superfamily member Ran GTP-binding protein (RanBP) 17 is still ill defined. Previously, we observed notable RanBP17 RNA expression levels in head and neck squamous cell carcinoma (HNSCC) cell lines with disruptive TP53 mutations.

Methods

We deployed HNSCC cell lines as well as cell lines from other tumor entities such as HCT116, MDA-MB-231 and H460, which were derived from colon, breast and lung cancers respectively. RNAi was used to evaluate the effect of RanBP17 on cell proliferation. FACS analysis was used for cell sorting according to their respective cell cycle phase and for BrdU assays. Immunocytochemistry was deployed for colocalization studies of RanBP17 with Nucleolin and SC35 (nuclear speckles) domains. TCGA analysis was performed for prognostic assessment and correlation analysis of RanBP17 in HNSCC patients.

Results

RNAi knockdown of RanBP17, significantly reduced cell proliferation in HNSCC cell lines. This effect was also seen in the HNSCC unrelated cell lines HCT116 and MDA-MB-231. Similarly, inhibiting cell proliferation with cisplatin reduced RanBP17 in keratinocytes but lead to induction in tumor cell lines. A similar observation was made in tumor cell lines after treatment with the EGFR kinase inhibitor AG1478. In addition to previous reports, showing colocalization of RanBP17 with SC35 domains, we observed colocalization of RanBP17 to nuclear bodies that are distinct from nucleoli and SC35 domains. Interestingly, for HPV positive but not HPV negative HNSCC, TCGA data base analysis revealed a strong positive correlation of RanBP17 RNA with patient survival and CDKN2A.

Conclusions

Our data point to a role of RanBP17 in proliferation of HNSCC and other epithelial cells. Furthermore, RanBP17 could potentially serve as a novel prognostic marker for HNSCC patients. However, we noted a major discrepancy between RanBP17 RNA and protein expression levels with the used antibodies. These observations could be explained by the presence of additional RanBP17 splice isoforms and more so of non-coding circular RanBP17 RNA species. These aspects need to be addressed in more detail by future studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09854-0.

New Drug Approvals for Sarcoma in the Last 5 Years

Sarcoma and locally aggressive connective tissue tumors are a complex group of diseases with a growing number of histotypes in the most recent WHO classification. Most of these tumors are rare (incidence <6/10⁵/y) or ultrarare (<1/10⁶/y). Despite their rarity, sarcomas are often good models for the development of personalized medicine, and a large number of new clinical trials in select histotypes and molecular subsets were reported during the past 5 years, leading to a faster rate of new drug approvals. We analyzed the published literature and the abstracts reported in major congresses dedicated to sarcoma and connective tissue tumor management in the last 5 years. Several targeted therapies, cytotoxic treatments, and immunotherapies have demonstrated activity in dedicated histologic and molecular subtypes of sarcomas. The majority of the studies for ultrarare entities are uncontrolled studies, as a consequence of the rarity of histotypes, but randomized controlled trials were available in the less rare histotypes. Most successful trials were based on biomarker selection, which were often driver molecular alterations, while a large number of ongoing research programs aim to identify biomarkers in parallel to new drug development. Availability of the new agents varies across countries. This article describes the new drugs that made it through to the finish line and new agents with promising activity that are in later stages of investigation in the large family of malignant connective tissue tumors.

The XPO1 Inhibitor KPT-8602 Ameliorates Parkinson's Disease by Inhibiting the NF-κB/NLRP3 Pathway

Exportin 1 (XPO1) is an important transport receptor that mediates the nuclear export of various proteins and RNA. KPT-8602 is a second-generation inhibitor of XPO1, demonstrating the lowest level of side effects, and is currently in clinical trials for the treatment of cancers. Previous studies suggest that several first-generation inhibitors of XPO1 demonstrate anti-inflammation activities, indicating the application of this drug in inflammation-related diseases. In this study, our results suggested the potent anti-inflammatory effect of KPT-8602 in vitro and in vivo. KPT-8602 inhibited the activation of the NF-κB pathway by blocking the phosphorylation and degradation of IκBα, and the priming of NLRP3. Importantly, the administration of KPT-8602 attenuated both lipopolysaccharide (LPS)-induced peripheral inflammation and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neuroinflammation in vivo. In addition, the tissue damage was also ameliorated by KPT-8602, indicating that KPT-8602 could be used as a novel potential therapeutic agent for the treatment of inflammasome-related diseases such as Parkinson’s disease, through the regulation of the NF-κB signaling pathway and the NLRP3 inflammasome.

The molecular mechanism and challenge of targeting XPO1 in treatment of relapsed and refractory myeloma

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Significant progress has been made on the treatment of MM during past two decades.

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Acquired drug-resistance continues to drive early relapse in primary refractory MM.

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XPO1 over-expression and cargo mislocalization are associated with drug-resistance.

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XPO1 inhibitor selinexor restores drug sensitivity to subsets of RR-MM cells.

Multiple myeloma (MM) treatment regimens have vastly improved since the introduction of immunomodulators, proteasome inhibitors, and anti-CD38 monoclonal antibodies; however, MM is considered an incurable disease due to inevitable relapse and acquired drug resistance. Understanding the molecular mechanism by which drug resistance is acquired will help create novel strategies to prevent relapse and help develop novel therapeutics to treat relapsed/refractory (RR)-MM patients. Currently, only homozygous deletion/mutation of TP53 gene due to “double-hits” on Chromosome 17p region is consistently associated with a poor prognosis. The exciting discovery of XPO1 overexpression and mislocalization of its cargos in the RR-MM cells has led to a novel treatment options. Clinical studies have demonstrated that the XPO1 inhibitor selinexor can restore sensitivity of RR-MM to PIs and dexamethasone. We will elaborate on the problems of MM treatment strategies and discuss the mechanism and challenges of using XPO1 inhibitors in RR-MM therapies while deliberating potential solutions.

Small molecule inhibitors of nuclear export ameliorate lupus by modulating plasma cell generation and survival

OBJECTIVE

To investigate the hypothesis that selective inhibitors of nuclear export (SINE), recently approved for the treatment of refractory plasma cell (PC) malignancy, may have potential in the treatment of lupus.

METHODS

NZB/NZW female mice were treated with SINE or vehicle control. Tissue was harvested and analyzed by flow cytometry using standard markers. Nephritis was monitored by evaluation for proteinuria and by histologic analysis of kidneys. Serum anti- double-stranded DNA (anti-dsDNA) levels were measured by enzyme-linked immunosorbent assay (ELISA) and total IgG and dsDNA antibody-secreting cells (ASC) by enzyme-linked immunospot assay.

RESULTS

SINE abrogated murine lupus nephritis at both early and late stages of the disease and rapidly impaired generation of autoreactive PC in germinal centers (GC). SINE inhibited the production of the NF-κB-driven homeostatic chemokines by stromal cells, altering splenic B and T cell strategic positioning and significantly reducing T follicular helper cells (TFH), GC B cells, and autoreactive PC. SINE also decreased cytokines/chemokines involved in PC survival and recruitment in the kidney of lupus-prone mice. Exportin 1, the SINE target, was detected in GC of human tonsils, splenic B cells of lupus patients, and multiple B cell subsets in the kidney of patients with lupus nephritis.

CONCLUSION

Our collective results support the therapeutic potential of SINE via targeting several molecular and cellular pathways critical in lupus pathogenesis, including autoantibody production by plasma cells.

Bisphenol A replacement chemicals, BPF and BPS, induce protumorigenic changes in human mammary gland organoid morphology and proteome

SignificanceBisphenol A (BPA), found in many plastic products, has weak estrogenic effects that can be harmful to human health. Thus, structurally related replacements-bisphenol S (BPS) and bisphenol F (BPF)-are coming into wider use with very few data about their biological activities. Here, we compared the effects of BPA, BPS, and BPF on human mammary organoids established from normal breast tissue. BPS disrupted organoid architecture and induced supernumerary branching. At a proteomic level, the bisphenols altered the abundance of common targets and those that were unique to each compound. The latter included proteins linked to tumor-promoting processes. These data highlighted the importance of testing the human health effects of replacements that are structurally related to chemicals of concern.

The regulation of Msx1 by BMP4/pSmad1/5 signaling is mediated by importin7 in dental mesenchymal cells

Msx1 is essential for the maintenance of the odontogenic fate of dental mesenchymal cells, and is regulated by BMP/Smad1/5 signaling in a Smad4-independent manner. However, the exact co-factors that assist pSmad1/5 entering the nucleus to regulate Msx1 in dental mesenchymal cells are still unknown. Importin7 (IPO7) is one of the important members of importin β-superfamily, which is mainly responsible for nucleocytoplasmic shuttling of RNAs and proteins, including transcription factors. This study aims to investigate whether IPO7 participates in the nuclear translocation of pSmad1/5 activated by BMP4 to regulate Msx1 expression in mouse dental mesenchymal cells. In the current study, we found that IPO7 was strongly expressed in the mouse dental mesenchymal cells at postnatal day 1 (PN1) both in vitro and in vivo. With BMP4 stimulation, IPO7 showed a translocation from the cytoplasm to the nucleus. Knockdown of IPO7 with siRNA inhibited the nuclear accumulation of pSmad1/5 in response to BMP4 stimulation. Furthermore, the co-immunoprecipitation assay showed pSmad1/5 was a nuclear import cargo of IPO7. Next, knockdown of IPO7 abolished the upregulation of Msx1 induced by BMP4, while overexpression of Smad1 was able to rescue the Msx1 expression. Finally, ChIP and Re-ChIP assay showed IPO7 facilitated the recruitment of pSmad1/5 to the Msx1 promoter. Taken together, our data demonstrated that the regulation of Msx1 by BMP4/pSmad1/5 signaling is mediated by importin7 in mouse dental mesenchymal cells.

Overview of systemic therapy options in liposarcoma, with a focus on the activity of selinexor, a selective inhibitor of nuclear export in dedifferentiated liposarcoma

Liposarcoma (LPS) is a common soft tissue sarcoma that encompasses diverse subtypes of well-differentiated/dedifferentiated, myxoid/round cell, and pleomorphic LPS. There is heterogeneity among the various LPS types with regard to prognosis, molecular pathogenesis, and response to treatment. Well-differentiated (WDLPS) and dedifferentiated liposarcoma (DDLPS) are most common types, which share common genetic alteration of chromosome 12q13-15 amplification resulting in amplification of oncogenes, including MDM2 (Mouse double minute 2), CDK4 (cyclin-dependent kinase 4), and HMGA2 (High mobility group protein AT-hook 2). Despite sharing the same molecular alteration, DDLPS has a worse prognosis, with a higher recurrence rate and higher propensity for metastases compared to WDLPS. Here we provide an overview of the LPS treatment landscape focusing on recent developments in the treatment of DDLPS with a focus on selinexor. Selinexor, a selective inhibitor of XPO1, was recently evaluated in a phase 3 trial, the first prospective randomized trial in DDLPS, and we discuss its efficacy in context of other available agents for DDLPS.

Nuclear Transporting Factor 2 as a Novel Biomarker of Head and Neck Squamous Cell Carcinoma and Associated with T/B Cell Receptor Signaling Pathway

Objective

This study is aimed at exploring the role of nuclear transporting factor 2 (NUTF2) in head and neck squamous cell carcinoma (HNSCC) based on The Cancer Genome Atlas (TCGA) database.

Methods

We obtained 528 HNSCC patients' clinical data from TCGA and performed expression level analysis of NUTF2. Gene Sets Enrichment Analysis (GSEA) was conducted to identify NUTF2-associated regulatory mechanisms in HNSCC. In addition, several other tools were used to enrich the regulatory network.

Results

We found that NUTF2 was significantly upregulated (P < 0.001) in HNSCC. We then observed that higher NUTF2 is associated with poorer overall survival and disease-free survival. Further, by using Cox analyses, we determined high NUTF2 as an independent risk factor of predicting poorer overall survival. Tumor immune infiltration analysis revealed a significantly negative correlation between NUTF2 expression and the level of tumor infiltrated CD8⁺ T cell and B cell, suggesting that NUTF2 may be involved in the immune regulation of HNSCC. Gene sets related to T/B cell receptor signaling pathways were differentially enriched based on the NUTF2 expression phenotype. KEGG pathways were used to show that NUTF2 may affect proliferation, differentiation, and immune response of T/B cell through regulating PI3K/AKT, NFκB, MAPK, and Calcium signaling pathways.

Conclusion

NUTF2 might be a valuable biomarker for HNSCC and correlated with T/B cell receptor signaling pathway.

The interaction between S100A2 and KPNA2 mediates NFYA nuclear import and is a novel therapeutic target for colorectal cancer metastasis

Nucleocytoplasmic transport of proteins is disrupted and dysregulated in cancer cells. Nuclear pore complexes and cargo proteins are two main transportation regulators. However, the mechanism regulating nucleocytoplasmic transport in cancer remains elusive. Here, we identified a S100A2/KPNA2 cotransport complex that transports the tumor-associated transcription factor NFYA in colorectal cancer (CRC). Through the S100A2/KNPA2 complex, depending on its interaction with S100A2, NFYA is transported to the nucleus and inhibits the transcriptional activity of E-cadherin, which in turn promotes CRC metastasis. Targeting the S100A2/KPNA2 binding sites with the specific inhibitor delanzomib is a potential therapeutic approach for CRC.

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.

Fragile X–Related Protein 1 Regulates Nucleoporin Localization in a Cell Cycle–Dependent Manner

Nuclear pore complexes (NPCs) are embedded in the nuclear envelope (NE) where they ensure the transport of macromolecules between the nucleus and the cytoplasm. NPCs are built from nucleoporins (Nups) through a sequential assembly order taking place at two different stages during the cell cycle of mammalian cells: at the end of mitosis and during interphase. In addition, fragile X–related proteins (FXRPs) can interact with several cytoplasmic Nups and facilitate their localization to the NE during interphase likely through a microtubule-dependent mechanism. In the absence of FXRPs or microtubule-based transport, Nups aberrantly localize to the cytoplasm forming the so-called cytoplasmic nucleoporin granules (CNGs), compromising NPCs’ function on protein export. However, it remains unknown if Nup synthesis or degradation mechanisms are linked to the FXRP–Nup pathway and if and how the action of FXRPs on Nups is coordinated with the cell cycle progression. Here, we show that Nup localization defects observed in the absence of FXR1 are independent of active protein translation. CNGs are cleared in an autophagy- and proteasome-independent manner, and their presence is restricted to the early G1 phase of the cell cycle. Our results thus suggest that a pool of cytoplasmic Nups exists that contributes to the NPC assembly specifically during early G1 to ensure NPC homeostasis at a short transition from mitosis to the onset of interphase.

Orthogonal ubiquitin transfer reveals human papillomavirus E6 downregulates nuclear transport to disarm interferon-γ dependent apoptosis of cervical cancer cells

The E6 protein of the human papillomavirus (HPV) underpins important protein interaction networks between the virus and host to promote viral infection. Through its interaction with E6AP, a host E3 ubiquitin (UB) ligase, E6 stirs the protein ubiquitination pathways toward the oncogenic transformation of the infected cells. For a systematic measurement of E6 reprogramming of the substrate pool of E6AP, we performed a proteomic screen based on "orthogonal UB transfer (OUT)" that allowed us to identify the ubiquitination targets of E6AP dependent on the E6 protein of HPV-16, a high-risk viral subtype for the development of cervical cancer. The OUT screen identified more than 200 potential substrates of the E6-E6AP pair based on the transfer of UB from E6AP to the substrate proteins. Among them, we verified that E6 would induce E6AP-catalyzed ubiquitination of importin proteins KPNA1-3, protein phosphatase PGAM5, and arginine methyltransferases CARM1 to trigger their degradation by the proteasome. We further found that E6 could significantly reduce the cellular level of KPNA1 that resulted in the suppression of nuclear transport of phosphorylated STAT1 and the inhibition of interferon-γ-induced apoptosis in cervical cancer cells. Overall, our work demonstrates OUT as a powerful proteomic platform to probe the interaction of E6 and host cells through protein ubiquitination and reveals a new role of E6 in down-regulating nuclear transport proteins to attenuate tumor-suppressive signaling.

RanBP3 Regulates Proliferation, Apoptosis and Chemosensitivity of Chronic Myeloid Leukemia Cells via Mediating SMAD2/3 and ERK1/2 Nuclear Transport

Abnormal subcellular localization of proteins is an important cause of tumorigenesis and drug resistance. Chromosome region maintenance 1 (CRM1), the nuclear export regulator of most proteins, has been confirmed to be over-expressed in various malignancies and is regarded as an efficient target. But the potential role of the CRM1 cofactor RanBP3 (Ran Binding Protein 3) is left unrevealed in chronic myeloid leukemia (CML). Here, we first detected the level of RanBP3 in CML and found an elevated RanBP3 expression in CML compared with control. Then we used shRNA lentivirus to down-regulated RanBP3 in imatinib sensitive K562 cells and resistant K562/G01 cells and found RanBP3 silencing inhibited cell proliferation by up-regulating p21, induced caspase3-related cell apoptosis, and enhanced the drug sensitivity of IM in vitro. Notably, we observed that RanBP3 silencing restored imatinib sensitivity of K562 cells in NOD/SCID mice. Mechanistically, the nuclear aggregation of SMAD2/3 revealed that tumor suppressor axis (TGF-β)-SMAD2/3-p21 was the anti-proliferation program related to RanBP3 knockdown, and the decrease of cytoplasmic ERK1/2 caused by RanBP3 interference leaded to the down-regulation of anti-apoptosis protein p(Ser112)-BAD, which was the mechanism of increased cell apoptosis and enhanced chemosensitivity to imatinib in CML. In summary, this study revealed the expression and potential role of RanBP3 in CML, suggesting that targeting RanBP3 alone or combined with TKIs could improve the clinical response of CML.

Role of Ras-related Nuclear Protein/Polypyrimidine Tract Binding Protein in Facilitating the Replication of Hepatitis C Virus

BACKGROUND AND AIMS

Ras-related nuclear (RAN) protein is a small GTP-binding protein that is indispensable for the translocation of RNA and proteins through the nuclear pore complex. Recent studies have indicated that RAN plays an important role in virus infection. However, the role of RAN in hepatitis C virus (HCV) infection is unclear. The objective of this study was to investigate the role and underlying mechanisms of RAN in HCV infection.

METHODS

Huh7.5.1 cells were infected with the JC1-Luc virus for 24 h and then were incubated with complete medium for an additional 48 h. HCV infection and RAN expression were determined using luciferase assay, quantitative reverse transcription-PCR and western blotting. Small interfering RNA was used to silence RAN. Western blotting and immunofluorescence were used to evaluate the cytoplasmic translocation of polypyrimidine tract-binding (PTB), and coimmunoprecipitation was used to examine the interaction between RAN and PTB.

RESULTS

HCV infection significantly induced RAN expression and cytoplasmic redistribution of PTB. Knockdown of RAN dramatically inhibited HCV infection and the cytoplasmic accumulation of PTB. Colocalization of RAN and PTB was determined by immunofluorescence, and a direct interaction of RAN with PTB was demonstrated by coimmunoprecipitation.

CONCLUSIONS

PTB in the host cytoplasm is directly associated with HCV replication. These findings demonstrate that the involvement of RAN in HCV infection is mediated by influencing the cytoplasmic translocation of PTB.

RAN and YBX1 are required for cell proliferation and IL-4 expression and linked to poor prognosis in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is one of the most common malignancies in the world, with a high mortality rate. RAN is a member of the Ras GTPase family and is overexpressed in a range of cancers, however, the relationship between RAN and OSCC is rarely reported. In this study, we found that RAN is overexpressed in OSCC tissues. RAN inhibition retarded OSCC cell proliferation and led to apoptosis and cell cycle arrest. Knockdown of RAN inhibited tumor growth in vivo. Strikingly, we found that RAN and oncogene Y-box binding protein-1 (YBX1) are positively associated with the immune infiltrates of CD4⁺ Th2 cells in multiple types of cancer, and can promote IL-4 expression. IL-4 treatment can partially rescue RAN knockdown-induced cell apoptosis in OSCC cells. Moreover, overexpression of RAN could rescue cell growth inhibition caused by knockdown of YBX1. Furthermore, patients with low expression of both RAN and YBX1 had better overall survival than others. Collectively, these findings indicate that RAN is a target of YBX1. RAN and YBX1 are required for cell proliferation and IL-4 expression. RAN and YBX1 are co-expressed and can serve as potential co-biomarkers for poor prognosis in OSCC.