Advances in the understanding of nuclear pore complexes in human diseases

BACKGROUND

Nuclear pore complexes (NPCs) are sophisticated and dynamic protein structures that straddle the nuclear envelope and act as gatekeepers for transporting molecules between the nucleus and the cytoplasm. NPCs comprise up to 30 different proteins known as nucleoporins (NUPs). However, a growing body of research has suggested that NPCs play important roles in gene regulation, viral infections, cancer, mitosis, genetic diseases, kidney diseases, immune system diseases, and degenerative neurological and muscular pathologies.

PURPOSE

In this review, we introduce the structure and function of NPCs. Then We described the physiological and pathological effects of each component of NPCs which provide a direction for future clinical applications.

METHODS

The literatures from PubMed have been reviewed for this article.

CONCLUSION

This review summarizes current studies on the implications of NPCs in human physiology and pathology, highlighting the mechanistic underpinnings of NPC-associated diseases.

The 8p11 myeloproliferative syndrome: Genotypic and phenotypic classification and targeted therapy

EMS(8p11 myeloproliferative syndrome, EMS) is an aggressive hematological neoplasm with/without eosinophilia caused by a rearrangement of the FGFR1 gene at 8p11-12. It was found that all cases carry chromosome abnormalities at the molecular level, not only the previously reported chromosome translocation and insertion but also a chromosome inversion. These abnormalities produced 17 FGFR1 fusion genes, of which the most common partner genes are ZNF198 on 13q11-12 and BCR of 22q11.2. The clinical manifestations can develop into AML (acute myeloid leukemia), T-LBL (T-cell lymphoblastic lymphoma), CML (chronic myeloid leukemia), CMML (chronic monomyelocytic leukemia), or mixed phenotype acute leukemia (MPAL). Most patients are resistant to traditional chemotherapy, and a minority of patients achieve long-term clinical remission after stem cell transplantation. Recently, the therapeutic effect of targeted tyrosine kinase inhibitors (such as pemigatinib and infigratinib) in 8p11 has been confirmed in vitro and clinical trials. The TKIs may become an 8p11 treatment option as an alternative to hematopoietic stem cell transplantation, which is worthy of further study.

Identification of a novel HOOK3-FGFR1 fusion gene involved in activation of the NF-kappaB pathway

Background

Rearrangements involving the fibroblast growth factor receptor 1 (FGFR1) gene result in 8p11 myeloproliferative syndrome (EMS), which is a rare and aggressive hematological malignancy that is often initially diagnosed as myelodysplastic syndrome (MDS). Clinical outcomes are typically poor due to relative resistance to tyrosine kinase inhibitors (TKIs) and rapid transformation to acute leukemia. Deciphering the transcriptomic signature of FGFR1 fusions may open new treatment strategies for FGFR1 rearrangement patients.

Methods

DNA sequencing (DNA-seq) was performed for 20 MDS patients and whole exome sequencing (WES) was performed for one HOOK3-FGFR1 fusion positive patient. RNA sequencing (RNA-seq) was performed for 20 MDS patients and 8 healthy donors. Fusion genes were detected using the STAR-Fusion tool. Fluorescence in situ hybridization (FISH), quantitative real-time PCR (qRT-PCR), and Sanger sequencing were used to confirm the HOOK3-FGFR1 fusion gene. The phosphorylation antibody array was performed to validate the activation of nuclear factor-kappaB (NF-kappaB) signaling.

Results

We identified frequently recurrent mutations of ASXL1 and U2AF1 in the MDS cohort, which is consistent with previous reports. We also identified a novel in-frame HOOK3-FGFR1 fusion gene in one MDS case with abnormal monoclonal B-cell lymphocytosis and ring chromosome 8. FISH analysis detected the FGFR1 break-apart signal in myeloid blasts only. qRT-PCR and Sanger sequencing confirmed the HOOK3-FGFR1 fusion transcript with breakpoints located at the 11th exon of HOOK3 and 10th exon of FGFR1, and Western blot detected the chimeric HOOK3-FGFR1 fusion protein that is presumed to retain the entire tyrosine kinase domain of FGFR1. The transcriptional feature of HOOK3-FGFR1 fusion was characterized by the significant enrichment of the NF-kappaB pathway by comparing the expression profiling of FGFR1 fusion positive MDS with 8 healthy donors and FGFR1 fusion negative MDS patients. Further validation by phosphorylation antibody array also showed NF-kappaB activation, as evidenced by increased phosphorylation of p65 (Ser 536) and of IKBalpha (Ser 32).

Conclusions

The HOOK3-FGFR1 fusion gene may contribute to the pathogenesis of MDS and activate the NF-kappaB pathway. These findings highlight a potential novel approach for combination therapy for FGFR1 rearrangement patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-022-02451-y.

[Inhibitory Eefects of the novel tyrosine kinase inhibitor BGJ398 against human leukemic cell line KG-1 cells]

目的

探讨针对FGFR1的酪氨酸激酶抑制剂BGJ398对人急性髓系白血病细胞株KG-1细胞的影响及可能的作用机制。

方法

CCK-8法检测BGJ398对KG-1细胞增殖的影响；流式细胞术Annexin Ⅴ/PI双重染色法检测BGJ398对细胞凋亡的影响；RQ-PCR检测细胞凋亡相关基因的表达；Western blot法检测凋亡相关蛋白、FGFR1OP2-FGFR1融合蛋白及信号通路分子磷酸化水平的表达变化。

结果

BGJ398能有效抑制KG-1细胞增殖，抑制率呈剂量依赖性升高，并能诱导细胞凋亡。BGJ398作用KG-1细胞48 h后，与对照组比较凋亡相关基因Bcl-2表达下降（0.342±0.054对1.026±0.165，t=3.94，P=0.017），caspase-3表达上调（0.456±0.189对1.008±0.091，t=16.44，P<0.001），差异均有统计学意义。与对照组相比，BGJ398作用组caspase-3活化蛋白表达增加，同时Bcl-2蛋白表达下调；FGFR1OP2-FGFR1融合蛋白水平及AKT、S6K1磷酸化水平下调，差异均有统计学意义（P值均<0.01），但ERK磷酸化表达水平无明显改变。

结论

BGJ398能有效抑制KG-1细胞增殖并诱导细胞凋亡，其机制可能与抑制FGFR1表达、下调Bcl-2水平、促进Caspase-3活化及抑制AKT和S6K磷酸化有关。

Recent Studies on Ponatinib in Cancers Other Than Chronic Myeloid Leukemia

Ponatinib is a third line drug for the treatment of chronic myeloid leukemia patients, especially those that develop the gatekeeper mutation T315I, which is resistant to the first and the second line drugs imatinib, nilotinib, dasatinib and bosutinib. The compound was first identified as a pan Bcr-Abl and Src kinase inhibitor. Further studies have indicated that it is a multitargeted inhibitor that is active on FGFRs, RET, AKT, ERK1/2, KIT, MEKK2 and other kinases. For this reason, the compound has been evaluated on several cancers in which these kinases play important roles, including thyroid, breast, ovary and lung cancer, neuroblastoma, rhabdoid tumours and in myeloproliferative disorders. Ponatinib is also being tested in clinical trials to evaluate its activity in FLT3-ITD acute myelogenous leukemia, head and neck cancers, certain type of lung cancer, gastrointestinal stromal tumours and other malignancies. In this review we report the most recent preclinical and clinical studies on ponatinib in cancers other than CML, with the aim of giving a complete overview of this interesting compound.

Structural Basis of TPR-Mediated Oligomerization and Activation of Oncogenic Fusion Kinases

The nuclear pore complex subunit TPR is found in at least five different oncogenic fusion kinases, including TPR-MET, yet how TPR fusions promote activation of kinases and their oncogenic activities remains poorly understood. Here we report the crystal structure of TPR(2-142), the MET fusion partner of oncogenic TPR-MET. TPR(2-142) contains a continuous 124-residue α helix that forms an antiparallel tetramer from two leucine zipper-containing parallel coiled coils. Remarkably, single mutations cause strikingly different conformations of the coiled coil, indicating its highly dynamic nature. We further show that fusion of TPR(2-142) to the MET intracellular domain strongly and selectively stabilizes the αG helix of the MET kinase domain, and mutations of only the TPR leucine zipper residues at the junction to MET, but not other leucine zipper residues, abolish kinase activation. Together, these results provide critical insight into the TPR structure and its ability to induce dimerization and activation of fusion kinases.

Pediatric 8p11 eosinophilic myeloproliferative syndrome (EMS): A case report and review of the literature

The 8p11 eosinophilic myeloproliferative syndrome (EMS) is an aggressive neoplasm driven by translocation of the fibroblast growth factor receptor 1 and often transforms to leukemias and lymphomas that are refractory to treatment. The first case was identified in 1983, and to date over 70 cases have been reported in the literature. Despite those reports, no consensus exists on management of this condition, and inconsistency in treatment regimens is even more pronounced in the pediatric literature. We report a case of a male infant with the 8p11 EMS, review the published pediatric experience with EMS, and discuss treatment strategies for this enigmatic hematological disorder.

Receptor Tyrosine Kinases: Translocation Partners in Hematopoietic Disorders

Receptor tyrosine kinases (RTKs) activate various signaling pathways and regulate cellular proliferation, survival, migration, and angiogenesis. Malignant neoplasms often circumvent or subjugate these pathways by promoting RTK overactivation through mutation or chromosomal translocation. RTK translocations create a fusion protein containing a dimerizing partner fused to an RTK kinase domain, resulting in constitutive kinase domain activation, altered RTK cellular localization, upregulation of downstream signaling, and novel pathway activation. While RTK translocations in hematological malignancies are relatively rare, clinical evidence suggests that patients with these genetic abnormalities benefit from RTK-targeted inhibitors. Here, we present a timely review of an exciting field by examining RTK chromosomal translocations in hematological cancers, such as Anaplastic Lymphoma Kinase (ALK), Fibroblast Growth Factor Receptor (FGFR), Platelet-Derived Growth Factor Receptor (PDGFR), REarranged during Transfection (RET), Colony Stimulating Factor 1 Receptor (CSF1R), and Neurotrophic Tyrosine Kinase Receptor Type 3 (NTRK3) fusions, and discuss current therapeutic options.

[A rare case of myeloproliferative disease with t(8;13)(p11;q12) associated with eosinophilia and lymphadenopathy]

Myeloproliferative disease associated with FGFR1 rearrangement (8p11), which is included in the 2008 WHO Classification of Myeloid Neoplasms, is a rare and extremely aggressive abnormality. The paper describes a clinical case of a 39-year-old female patient who was detected to have leukocytosis (as high as 47.2·109/l), absolute eosinophilia (as high as 3.1·109/l), and enlarged peripheral lymph nodes during her visit to a doctor. The bone marrow (BM) showed the changes typically encountered in myeloproliferative disease with eosinophilia. The patient was found to have t(8;13)(p11;q12) translocation associated with the rearrangement of the FGFR1 gene located at the 8p11 locus. Molecular and cytogenetic examinations failed to reveal BCR-ABL chimeric transcript, Jak2 V617F mutation, and deletions and translocations involving PDGFRA (4q12) and PDGFRB (5q32-33). The similar changes in the karyotype were also found in the lymph node cells. The undertaken treatment with hydroxyurea and the tyrosine kinase inhibitor dasatinib turned out to be ineffective. The patient underwent allogeneic BM transplantation from a HLA-identical sibling. Graft rejection occurred 6 months later. Allogeneic BM transplantation from the same donor (100% donor chimerism; FGFR1/8р11 translocation was not detected), which was complicated by the development of chronic graft-versus-host reaction, was performed again in March 2015. The patient is being followed up and continues to receive immunosuppressive therapy.