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

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

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

HIRA loss transforms FH-deficient cells

Fumarate hydratase (FH) is a mitochondrial enzyme that catalyzes the reversible hydration of fumarate to malate in the tricarboxylic acid (TCA) cycle. Germline mutations of FH lead to hereditary leiomyomatosis and renal cell carcinoma (HLRCC), a cancer syndrome characterized by a highly aggressive form of renal cancer. Although HLRCC tumors metastasize rapidly, FH-deficient mice develop premalignant cysts in the kidneys, rather than carcinomas. How Fh1-deficient cells overcome these tumor-suppressive events during transformation is unknown. Here, we perform a genome-wide CRISPR-Cas9 screen to identify genes that, when ablated, enhance the proliferation of Fh1-deficient cells. We found that the depletion of the histone cell cycle regulator (HIRA) enhances proliferation and invasion of Fh1-deficient cells in vitro and in vivo. Mechanistically, Hira loss activates MYC and its target genes, increasing nucleotide metabolism specifically in Fh1-deficient cells, independent of its histone chaperone activity. These results are instrumental for understanding mechanisms of tumorigenesis in HLRCC and the development of targeted treatments for patients.

MicroRNA-517c Functions as a Tumor Suppressor in Hepatocellular Carcinoma via Downregulation of KPNA2 and Inhibition of PI3K/AKT Pathway

OBJECTIVE

Hepatocellular carcinoma (HCC) is a kind of solid and highly aggressive malignant tumor with poor prognosis. MicroRNA (miRNA/miR) has been confirmed to be involved in HCC development. The current study focused on the functions and mechanisms of miR-517c in HCC.

METHODS

Expressions of miR-517c and Karyopherin α2 (KPNA2) mRNA in HCC cell lines and tissue samples were examined using quantitative real-time polymerase chain reaction (qRT-PCR). Western blot was conducted for detections of epithelial-to-mesenchymal transition (EMT) and PI3K/AKT markers. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and Transwell assays were utilized to investigate the influence of miR-517c on HCC cell proliferation, invasion, and migration. TargetScan and luciferase reporter assay were performed to search for the potential target gene of miR-517c.

RESULTS

We demonstrated that miR-517c expressions were decreased in HCC tissues and cells. Moreover, the clinical analysis showed that decreased miR-517c expressions in HCC tissues correlated with shorter overall survival and malignant clinicopathologic features of HCC patients. MTT assay showed that miR-517c upregulation prominently repressed HCC cell proliferation. In addition, miR-517c restoration could significantly suppress HCC cell invasion and migration as demonstrated by Transwell assays. We also found that miR-517c directly targeted KPNA2 and regulated the PI3K/AKT pathway and EMT, exerting prohibitory functions in HCC.

CONCLUSION

Taken together, this study stated that miR-517c inhibited HCC progression via regulating the PI3K/AKT pathway and EMT and targeting KPNA2 in HCC, providing a novel insight into HCC treatment.

Mitophagy-associated genes PINK1 and PARK2 are independent prognostic markers of survival in papillary renal cell carcinoma and associated with aggressive tumor behavior

The aim of this study was to investigate the mitophagy-related genes PINK1 and PARK2 in papillary renal cell carcinoma and their association with prognosis. In silico data of PINK1 and PARK2 were analyzed in TCGA cohorts of papillary renal cell carcinoma comprising 290 tumors and 33 corresponding non-neoplastic renal tissues. Protein expression data from a cohort of 95 papillary renal cell carcinoma patients were analyzed and associated with clinical-pathological parameters including survival. PINK1 and PARK2 were significantly downregulated in papillary renal cell carcinoma at transcript and protein levels. Reduced transcript levels of PINK1 and PARK2 were negatively associated with overall survival (p < 0.05). At the protein level, PARK2 and PINK1 expression were positively correlated (correlation coefficient 0.286, p = 0.04) and reduced PINK1 protein expression was prognostic for shorter survival. Lower PINK1 protein levels were found in tumors with metastases at presentation and in tumors of higher pT-stages. The multivariate analysis revealed mRNA expression of PINK1 and PARK2 as well as PINK1 protein expression as independent prognostic factors for shorter overall survival. The downregulation of PINK1 is a strong predictor of poor survival in papillary renal cell carcinoma. Immunohistochemical PINK1 expression in resected pRCC should be considered as an additional prognostic marker for routine practice.

KPNA2-Associated Immune Analyses Highlight the Dysregulation and Prognostic Effects of GRB2, NRAS, and Their RNA-Binding Proteins in Hepatocellular Carcinoma

Karyopherin α2 (KPNA2) was reported to be overexpressed and have unfavorable prognostic effects in many malignancies including hepatocellular carcinoma (HCC). Although its contributions to inflammatory response were reported in many studies, its specific associations with immune infiltrations and immune pathways during cancer progression were unclear. Here, we aimed to identify new markers for HCC diagnosis and prognosis through KPNA2-associated immune analyses. RNA-seq expression data of HCC datasets were downloaded from The Cancer Genome Atlas and International Cancer Genome Consortium. The gene expressions were counts per million normalized. The infiltrations of 24 kinds of immune cells in the samples were evaluated with ImmuCellAI (Immune Cell Abundance Identifier). The Spearman correlations of the immune infiltrations with KPNA2 expression were investigated, and the specific positive correlation of B-cell infiltration with KPNA2 expression in HCC tumors was identified. Fifteen genes in KEGG (Kyoto Encyclopedia of Genes and Genomes) B-cell receptor signaling pathway presented significant correlations with KPNA2 expression in HCC. Among them, GRB2 and NRAS were indicated to be independent unfavorable prognostic factors for HCC overall survival. Clinical Proteomic Tumor Analysis Consortium HCC dataset was investigated to validate the results at protein level. The upregulation and unfavorable prognostic effects of KPNA2 and GRB2 were confirmed, whereas, unlike its mRNA form, NRAS protein was presented to be downregulated and have favorable prognostic effects. Through receiver operating characteristic curve analysis, the diagnostic potential of the three proteins was shown. The RNA-binding proteins (RBPs) of KPNA2, NRAS, and GRB2, downloaded via The Encyclopedia of RNA Interactomes, were investigated for their clinical significance in HCC at protein level. An eight-RBP signature with independent prognostic value and dysregulations in HCC was identified. All the RBPs were significantly correlated with MKI67 expression and at least one of KPNA2, GRB2, and NRAS at protein level in HCC, indicating their roles in HCC progression and the regulation of the three proteins. We concluded that KPNA2, GRB2, NRAS, and their RBPs might have coordinating roles in HCC immunoregulation and progression. They might be new markers for HCC diagnosis and prognosis predication and new targets for HCC immunotherapy.

Expression, mutation, and methylation of cereblon-pathway genes at pre- and post-lenalidomide treatment in multiple myeloma

Cereblon (CRBN) is a target for immunomodulatory drugs. This study investigated the prognostic value of the expression of CRBN‐pathway genes on the clinical relevance of lenalidomide (Len) treatment and evaluated the levels of CRBN‐binding proteins and mutations in these genes after Len treatment. Forty‐eight primary multiple myeloma cells were collected prior to treatment with Len and dexamethasone (Ld) and 25 paired samples were obtained post‐Ld therapy. These tumor cells were used to determine the expression and mutated forms of the CRBN‐pathway genes. Following normalization with CRBN levels, there was a significantly reduced IKZF1/CRBN ratio in samples that responded poorly to Ld therapy. Moreover, patients with low ratios of IKZF1/CRBN showed a significantly shorter progression‐free survival (PFS) and overall survival (OS) than those with higher ratios. However, patients with high ratios of KPNA2/CRBN showed a significantly shorter PFS and OS than patients with lower ratios. Of the 25 paired samples analyzed, most samples showed a reduction in the expression of CRBN and an increase in IKZF1 gene expression. No mutations were observed in CRBN, IKZF1, or CUL4A genes in the post‐Ld samples. In conclusion, a decreased expression of IKZF1 and increased expression of KPNA2 compared to that of CRBN mRNA predicts poor outcomes of Ld therapy.

Overexpression of Karyopherin Subunit alpha 2 (KPNA2) Predicts Unfavorable Prognosis and Promotes Bladder Cancer Tumorigenicity via the P53 Pathway

Background

We sought to investigate the expression of KPNA2 in bladder cancer (BC) and its relationship with prognosis, and to analyze the potential mechanism of KPNA2 in promoting BC progression.

Material/Methods

The RNA-seq data on BC from The Cancer Genome Atlas (TCGA) database were imported into R statistical software for differential analysis. The clinical data for patients with BC were screened and analyzed with R software. The survival curve was drawn with the Kaplan-Meier Plotter. The expression of KPNA2 in 4 human BC cell lines and a human bladder epithelial cell line was detected by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting (WB). The proliferation of BC cells was detected with Cell Counting Kit-8 (CCK8), detection of apoptosis, and flow cytometry, and the migration and invasion of BC cells were detected through Transwell assays. WB was used to detect proteins involved in the P53 pathway.

Results

The expression of KPNA2 was higher in BC. The difference in KPNA2 expression was associated with many clinicopathological factors, and high expression of KPNA2 was associated with shorter survival time. After KPNA2 knockout, the proliferation, migration, and invasion ability decreased significantly, the cell cycle was clearly arrested in the G0/G1 phase, and the number of apoptotic cells increased. Moreover, CyclinD1, BCL2, and pro-caspase3 decreased significantly, whereas P53, P21, BAX, and cleaved-caspase3 increased significantly. The results in the overexpression group were the opposite of results in the knockdown group.

Conclusions

KPNA2 is an oncogenic factor that facilitates BC tumorigenicity through the P53 pathway.

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.