Karyopherin alpha 2 expression is a novel diagnostic and prognostic factor for colorectal cancer

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.

Silencing KPNA2 Promotes Ferroptosis in Laryngeal Cancer by Activating the FoxO Signaling Pathway

We aim to clarify the specific role of Karyopherin α2 (KPNA2) in the progression of laryngeal cancer, a kind of malignant tumor with a poor curative effect. We performed the bioinformatic analysis to obtain the ferroptosis-related differentially expressed genes. KPNA2 was screened out. Then the CCK-8 assay, wound healing assay, and transwell assay were used to clarify the changes in the proliferation, migration, and invasion abilities of laryngeal cancer cells after silencing KPNA2. The concentrations of iron ions, glutathione, superoxide dismutase, and malondialdehyde were evaluated by the corresponding detection kits. The expression levels of cyclooxygenase 2, Acyl-CoA synthetase long-chain family member 4, glutathione peroxidase 4, forkhead box O (FoxO)1a and FoxO3a were determined by Western Blot. A total of 45 ferroptosis-related differentially expressed genes in laryngeal cancer were obtained, and KPNA2 was selected after bioinformatic analysis. In ferroptosis-induced laryngeal cancer cells, the cell viability, migration rate, invasion ability, and the expression of glutathione peroxidase 4, glutathione, and superoxide dismutase were further decreased and the expression of cyclooxygenase 2, Acyl-CoA synthetase long-chain family member 4, iron ions, and malondialdehyde were further increased after silencing KPNA2. The expression levels of FoxO1a and FoxO3a in laryngeal cancer cells were increased by silencing KPNA2. KPNA2 may be a promising therapeutic target for laryngeal cancer. Down-regulation of KPNA2 can promote ferroptosis in laryngeal cancer by stimulating the FoxO signaling pathway.

Identification of Prognostic Genes for Colon Cancer through Gene Co-expression Network Analysis

OBJECTIVE

The present study was aimed to identify novel key genes, prognostic biomarkers and molecular pathways implicated in tumorigenesis of colon cancer.

METHODS

The microarray data GSE41328 containing 10 colon cancer samples and 10 adjacent normal tissues was analyzed to identify 4763 differentially expressed genes. Meanwhile, another microarray data GSE17536 was performed for weighted gene co-expression network analysis (WGCNA).

RESULTS

In present study, 12 co-expressed gene modules associated with tumor progression were identified for further studies. The red module showed the highest association with pathological stage by Pearson's correlation analysis. Functional enrichment analysis revealed that genes in red module focused on cell division, cell proliferation, cell cycle and metabolic related pathway. Then, a total of 26 key hub genes were identified, and GEPIA database was subsequently selected for validation. Holliday junction-recognizing protein (HJURP) and cell division cycle 25 homolog C (CDC25C) were identified as effective prognosis biomarkers, which were all detrimental to prognosis. Gene set enrichment analyses (GSEA) found the two hub genes were enriched in "oocyte meiosis", "oocyte maturation that are progesterone-mediated", "p53 signaling pathway", and "cell cycle". Furthermore, the immunohistochemistry and western blotting showed that HJURP was highly expressed in colon cancer tissue.

CONCLUSION

HJURP was identified as a key gene associated with colon cancer progression and prognosis by WGCNA, which might influence the prognosis by regulating cell cycle pathways.

Centromere Protein A (CENPA) Regulates Metabolic Reprogramming in the Colon Cancer Cells by Transcriptionally Activating Karyopherin Subunit Alpha 2 (KPNA2)

The karyopherin α₂ subunit gene (KPNA2) has been reported as an oncogene and is involved in metabolic reprogramming in cancer. This study aimed to explore the function of KPNα₂ in the growth and glycolysis in colon cancer (CC) cells. Genes from the Oncomine database that were differentially expressed in multiple CC types were screened. Bioinformatics analysis suggested that KPNA2 was highly expressed in CC: High expression of KPNA2 was detected in the CC cell lines. Down-regulation of KPNA2 reduced viability and DNA-replication ability, and it increased apoptosis of HCT116 and LoVo cells. It also reduced glucose consumption, extracellular acidification rate, and the ATP production in cells. Centromere protein A (CENPA) was confirmed as an upstream transcription activator of KPNA2. There was significant H3K27ac modification in the promoter region of KPNA2. CENPA mainly recruited histone acetyltransferase general control of amino acid synthesis (GCN)-5 to the promoter region of KPNA2 to induce transcription activation. Overexpression of either CENPA or GCN-5 blocked the role of short hairpin KPNα₂ and restored growth and glycolysis in CC cells. To conclude, the findings from this study suggest that CENPA recruits GCN-5 to the promoter region of KPNA2 to induce KPNα₂ activation, which strengthens growth and glycolysis in, and augments the development of, CC.

Importins: Diverse roles in male fertility

Regulated nucleocytoplasmic transport is central to the changes in gene expression that underpin cellular development and homeostasis, including in the testis, and proteins in the importin family are the predominant facilitators of cargo transport through the nuclear envelope. Reports documenting cell-specific profiles of importin transcripts and proteins during spermatogenesis led us to hypothesize that importins facilitate developmental switches in the testis. More recently, importins have been shown to serve additional functions, both inside and outside the nucleus; these include acting as subcellular scaffolding, mediating cellular stress responses, and controlling transcription. This paper seeks to provide an overview and update on the functions of importin proteins, with a focus on testis development and spermatogenesis. We present an extended survey of importins by combining published single cell RNAseq data with immunohistochemistry on developing and adult mouse testes. This approach reinforces and broadens knowledge of importins in biological processes, including in spermatogenesis and during testis development, revealing additional avenues for impactful investigations.

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

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

The emerging roles of KPNA2 in cancer

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

Protein Expression Profiling Identifies Key Proteins and Pathways Involved in Growth Inhibitory Effects Exerted by Guggulsterone in Human Colorectal Cancer Cells

Colorectal cancer (CRC) is a leading killer cancer worldwide and one of the most common malignancies with increasing incidences of mortality. Guggulsterone (GS) is a plant sterol used for treatment of various ailments such as obesity, hyperlipidemia, diabetes, and arthritis. In the current study, anti-cancer effects of GS in human colorectal cancer cell line HCT 116 was tested, potential targets identified using mass spectrometry-based label-free shotgun proteomics approach and key pathways validated by proteome profiler antibody arrays. Comprehensive proteomic profiling identified 14 proteins as significantly dysregulated. Proteins involved in cell proliferation/migration, tumorigenesis, cell growth, metabolism, and DNA replication were downregulated while the protein with functional role in exocytosis/tumor suppression was found to be upregulated. Our study evidenced that GS treatment altered expression of Bcl-2 mediated the mitochondrial release of cytochrome c which triggered the formation of apoptosome as well as activation of caspase-3/7 leading to death of HCT 116 cells via intrinsic apoptosis pathway. GS treatment also induced expression of p53 protein while p21 expression was unaltered with no cell cycle arrest. In addition, GS was found to inhibit NF-kB signaling in colon cancer cells by quelling the expression of its regulated gene products Bcl-2, cIAP-1, and survivin.

Karyopherin Alpha 2 Is an Adverse Prognostic Factor in Clear-Cell and Papillary Renal-Cell Carcinoma

BACKGROUND

Karyopherin α2 (KPNA2) is involved in the nucleocytoplasmic transport system and is functionally involved in the pathogenesis of various solid tumors by the translocation of cancer associated cargo proteins. However, the role of KPNA2 in renal-cell carcinoma (RCC) is still unknown. The aim of the present study was to investigate the protein expression of KPNA2 in cancerous and healthy renal tissues to evaluate its prognostic value in RCC.

PATIENTS AND METHODS

We assessed KPNA2 protein expression via immunohistochemistry in a well-characterized cohort of 240 RCC patients by using a quantitative image analysis software. In addition, we analyzed publicly available gene expression data from The Cancer Genome Atlas (TCGA).

RESULTS

A subgroup of clear-cell RCC (ccRCC) showed elevated protein expression levels of KPNA2. Most remarkably, we detected a correlation between high KPNA2 protein expression and shorter overall survival times as well as higher tumor stage and International Society of Urologic Pathology grade in ccRCC. However, the prognostic value of KPNA2 was not confirmed by multivariate Cox regression analysis when tested together with strong prognostic factors like tumor stage, lymph node metastasis, International Society of Urologic Pathology grade, and resection status. The results of the TCGA gene expression data analysis confirmed the prognostic value of KPNA2 in ccRCC. Additionally, KPNA2 expression was identified as an adverse factor in papillary RCC at the transcript level.

CONCLUSION

KPNA2 appears to be involved in the carcinogenesis of RCC and functions as a novel prognostic indicator.

Identifying autophagy gene-associated module biomarkers through construction and analysis of an autophagy-mediated ceRNA‑ceRNA interaction network in colorectal cancer

Autophagy is crucial in cellular homeostasis and has been implicated in the development of malignant tumors. However, the regulatory function of autophagy in cancer remains to be fully elucidated. In the present study, the autophagy-mediated competing endogenous RNA (ceRNA)-ceRNA interaction networks in colorectal cancer (CRC) were constructed by integrating systematically expression profiles of long non-coding RNAs and mRNAs. It was found that a large proportion of autophagy genes were inclined to target hub nodes, including a fraction of autophagy genes, by comparing with other genes within ceRNA networks, and showed preferential interaction with themselves. The present study also revealed that autophagy genes may be used as prognostic markers for cancer therapy. A risk score model based on multivariable Cox regression analysis was then used to capture novel biomarkers in connection with lncRNA for the prognosis of CRC. These biomarkers were confirmed in the test dataset and an additional independent dataset. Furthermore, the prognostic value of biomarkers is independent of conventional clinical factors. These results provide improved understanding of autophagy-mediated ceRNA regulatory mechanisms in CRC and provide novel potential molecular therapeutic targets for the diagnosis and treatment of CRC.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Karyopherins in cancer

Malfunction of nuclear-cytoplasmic transport contributes to many diseases including cancer. Defective nuclear transport leads to changes in both the physiological levels and temporal-spatial location of tumor suppressors, proto-oncogenes and other macromolecules that in turn affect the tumorigenesis process and drug sensitivity of cancer cells. In addition to their nuclear transport functions in interphase, Karyopherin nuclear transport receptors also have important roles in mitosis and chromosomal integrity. Therefore, alterations in the expressions or regular functions of Karyopherins may have substantial effects on the course and outcome of diseases.