mTOR regulates proteasomal degradation and Dp1/E2F1- mediated transcription of KPNA2 in lung cancer cells

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.

Association between Breast Cancer and Second Primary Lung Cancer among the Female Population in Taiwan: A Nationwide Population-Based Cohort Study

PURPOSE

A special association between breast cancer and second primary lung cancer in Taiwanese women has been discovered not only in clinical practice, but also in a large population-based study. We hereby investigate the association between breast cancer and second primary lung cancer in Taiwanese women.

METHODS

This study was conducted from the National Health Insurance Research Database (NHIRD) from Taiwan National Health Insurance (NHI). Patients older than 18 years old and hospitalized with a first diagnosis of breast cancer during 2000 to 2012 were enrolled in the breast cancer group. Patients who were cancer free were frequency-matched with the breast cancer group by age (every five-year span) and index year. The ratio of breast cancer group to non-breast cancer group was 1:4. The event as the outcome in this study was lung cancer. The comorbidities viewed as important confounding factors included coronary artery disease, stroke, hypertension, diabetes, chronic obstructive pulmonary disease, hyperlipidemia, tuberculosis, chronic kidney disease, and chronic liver disease and cirrhosis. We estimated the hazard ratios (HRs), adjusted hazard ratios (aHRs), and 95% confidence intervals (CIs) for risk of lung cancer in the breast cancer group and non-breast cancer group using Cox proportional hazard models. Sensitivity analysis was also done using propensity score matching. All of the statistical analyses were performed using SAS statistical software, version 9.4 (SAS Institute Inc., Cary, NC).

RESULTS

There were 94,451 breast cancer patients in the breast cancer group and 377,804 patients in the non-breast cancer group in this study. After being stratified by age, urbanization level, and comorbidities, the patients with breast cancer had a significantly higher risk of lung cancer compared with the patients without breast cancer, particularly for those who aged between 20 and 49 years (aHR = 2.10, 95% CI = 1.71-2.58), 50 and 64 years (aHR = 1.35, 95% CI = 1.15-1.58), and those without any comorbidities (aHR = 1.92, 95% CI = 1.64-2.23).

CONCLUSION

Patients with breast cancer had a significantly higher risk of developing second primary lung cancer compared with patients without breast cancer, particularly in younger groups and in those without any comorbidities. The special association may be attributed to some potential risk factors such as genetic susceptibility and long-term exposure to PM2.5, and is supposed to increase public awareness. Further studies are necessary given the fact that inherited genotypes, different subtypes of breast cancer and lung cancer, and other unrecognized etiologies may play vital roles in both cancers' development.

U2 small nuclear RNA auxiliary factor 2, transcriptionally activated by the transcription factor Dp-1/E2F transcription factor 1 complex, enhances the growth and aerobic glycolysis of leiomyosarcoma cells

The dysregulation of U2 Small Nuclear RNA Auxiliary Factor 2 (U2AF2) is associated with malignant behaviors of multiple types of tumors. In this study, we explored the association between U2AF2 dysregulation and the survival of patients with primary leiomyosarcoma, the regulatory effect of U2AF2 on cell growth/aerobic glycolysis, and the mechanisms of U2AF2 dysregulation at the transcriptional level. Gene expression and survival time of patients with primary leiomyosarcoma were extracted from TCGA-Sarcoma (SARC). Leiomyosarcoma cell lines SK-LMS-1 and SK-UT-1 were utilized to construct in vitro and in vivo models. Results showed that the higher U2AF2 expression group had significantly shorter progression-free survival (HR: 2.049, 95%CI: 1.136-3.697, p = 0.011) and disease-specific survival (4.656, 95%CI: 2.141-10.13, p < 0.001) compared to the lower U2AF2 expression group. U2AF2 knockdown suppressed leiomyosarcoma cell growth and aerobic glycolysis (decreased glucose uptake, lactate production, and extracellular acidification rate) in vitro. Tumors derived from SK-LMS-1 cells with U2AF2 knockdown grew significantly slower, with lower GLUT1, PGK1, and PGAM1 protein expression than the control groups. TFDP1 and E2F1 could interact with each other in leiomyosarcoma cells. Both TFDP1 and E2F1 could bind to the promoter of U2AF2 and exert a synergistic activating effect on U2AF2 transcription. In conclusion, this study revealed that U2AF2 upregulation is associated with poor survival of leiomyosarcoma. Its upregulation enhances proliferation and aerobic glycolysis of leiomyosarcoma cells in vitro and in vivo. TFDP1 and E2F1 can form a complex, which binds to the U2AF2 gene promoter and synergistically activates its transcription.

Nuclear accumulation of KPNA2 impacts radioresistance through positive regulation of the PLSCR1-STAT1 loop in lung adenocarcinoma

Lung adenocarcinoma (ADC) is the predominant histological type of lung cancer, and radiotherapy is one of the current therapeutic strategies for lung cancer treatment. Unfortunately, biological complexity and cancer heterogeneity contribute to radioresistance development. Karyopherin α2 (KPNA2) is a member of the importin α family that mediates the nucleocytoplasmic transport of cargo proteins. KPNA2 overexpression is observed across cancer tissues of diverse origins. However, the role of KPNA2 in lung cancer radioresistance is unclear. Herein, we demonstrated that high expression of KPNA2 is positively correlated with radioresistance and cancer stem cell (CSC) properties in lung ADC cells. Radioresistant cells exhibited nuclear accumulation of KPNA2 and its cargos (OCT4 and c‐MYC). Additionally, KPNA2 knockdown regulated CSC‐related gene expression in radioresistant cells. Next‐generation sequencing and bioinformatic analysis revealed that STAT1 activation and nuclear phospholipid scramblase 1 (PLSCR1) are involved in KPNA2‐mediated radioresistance. Endogenous PLSCR1 interacting with KPNA2 and PLSCR1 knockdown suppressed the radioresistance induced by KPNA2 expression. Both STAT1 and PLSCR1 were found to be positively correlated with dysregulated KPNA2 in radioresistant cells and ADC tissues. We further demonstrated a potential positive feedback loop between PLSCR1 and STAT1 in radioresistant cells, and this PLSCR1‐STAT1 loop modulates CSC characteristics. In addition, AKT1 knockdown attenuated the nuclear accumulation of KPNA2 in radioresistant lung cancer cells. Our results collectively support a mechanistic understanding of a novel role for KPNA2 in promoting radioresistance in lung ADC cells.

Oncogenic role of karyopherin α2 (KPNA2) in human tumors: A pan-cancer analysis

BACKGROUND

KPNA2, a nuclear export protein that plays an important role in tumorigenesis, is an emerging hotspot target in oncology. Despite increasing supporting evidence of its importance, no pan-cancer analysis, across multiple databases, is available for in-depth data mining of the gene.

METHODS

Tumor data from both The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) were explored to investigate the potential oncogenic roles of KPNA2. Diverse analytical methods were used to gain a full-scale understanding of KPNA2: gene expression, survival situations, genetic mutations, DNA methylation, sites of protein phosphorylation, immunocyte infiltration, and correlative cellular pathways.

RESULTS

KPNA2 is highly expressed in many cancers, and different correlations exist between KPNA2 expression and prognosis of cancer patients. cBioPortal reported that a nonsense mutation of R285* was considered to be the primary tumorigenic genetic alteration to KPNA2 and was found in cases of LUSC, STAD, and CESC. Enhanced phosphorylation of S62 was found in several cancers and the level of infiltration of cancer-associated fibroblasts was found to be linearly correlated with KPNA2 expression levels in ACC, BRCA, MESO, TGCT, THCA, and THYM. Correlations between KPNA2 DNA methylation and the pathogenesis of various tumors in TCGA were further identified. KEGG and GO enrichment analysis identified cell cycle, microtubule binding, and tubulin binding functions for KPNA2.

CONCLUSION

This is the first pan-cancer analysis focusing on KPNA2. It provides a comprehensive understanding about the role of KPNA2 in tumorigenesis and highlights the potential targeted role of KPNA2 for cancer study.

Curcumin-Alleviated Osteoarthritic Progression in Rats Fed a High-Fat Diet by Inhibiting Apoptosis and Activating Autophagy via Modulation of MicroRNA-34a

Purpose

The mechanism underlying curcumin’s protective effect on osteoarthritis (OA) has not been clarified. This study aimed to determine whether curcumin exerts a chondroprotective effect by inhibiting apoptosis via upregulation of E2F1/PITX1 and activation of autophagy via the Akt/mTOR pathway by targeting microRNA-34a (miR-34a).

Methods

Male Sprague–Dawley rats were fed a normal diet (ND) or high-fat diet (HFD) for 28 weeks. Five rats from each diet group were selected randomly for histological analysis of OA characteristics. Rats fed a HFD were given a single intra-stifle joint injection of the miR-34a mimic agomir-34a or negative control agomir (NC), followed by weekly low-dose (200 μg/kg body weight) or high-dose (400 μg/kg body weight) curcumin intra-joint injections from weeks 29 to 32. The rats’ stifle joints were submitted to histological analysis and to an apoptotic assay. Expression of miR-34a was detected using a real-time RT-PCR. E2F1 and PITX1 protein levels were determined by Western blot analysis, and the expressions of Beclin1, LC3B, p62, phosphorylated (p)-Akt, and p-mTOR were measured using immunofluorescence analysis.

Results

We found that rats fed a HFD had OA-like lesions in their articular cartilage and had increased apoptosis of chondrocytes and decreased autophagy compared to rats fed a ND. Curcumin treatment alleviated OA changes, inhibited apoptosis, and upregulated autophagy. Agomir-34a treatment reduced E2F1, PITX1, Beclin1, and LC3B expression and increased p62, p-Akt, and p-mTOR expression in HFD-fed rats given low- or high-dose curcumin. Greater numbers of apoptotic cells, lesser expression of p62, p-Akt, and p-mTOR, and greater expression of E2F1, PITX1, and LC3B were observed in the agomir-34a and high-dose curcumin-treated group than in agomir-34a and low-dose curcumin-treated group.

Conclusion

Curcumin’s chondroprotective effect was mediated by its suppression of miR-34a, apparently by reducing apoptosis, via upregulation of E2F1/PITX1, and by augmenting autophagy, likely via the Akt/mTOR pathway.

Analyses of DNA Methylation Involved in the Activation of Nuclear Karyopherin Alpha 2 Leading to Identify the Progression and Prognostic Significance Across Human Breast Cancer

Background

Karyopherin alpha 2 (KPNA2) is a nuclear import factor that plays a crucial role in nucleocytoplasmic transport, as well as cell proliferation, migration, and invasion in several cancers. However, the roles of KPNA2 in breast cancer as well as the underlying molecular mechanisms have not been elucidated.

Materials and Methods

To evaluate gene expression alterations during breast carcinogenesis, KPNA2 expression was analyzed using the Gene Expression Profiling Interactive Analysis and Oncomine analyses. The correlation between methylation and expression was analyzed using the MEXPRESS tool, UALCAN cancer database, and cBioPortal browser. Then, the expression and prognostic value of KPNA2 were investigated by our own breast cancer samples using RT-PCR. KPNA2 methylation level was detected by methylation-specific PCR.

Results

We obtained the following important results. (1) KPNA2 expression was significantly higher in breast cancer than normal samples and regulated by aberrant DNA hypomethylation of promoter region. (2) Among patients with breast cancer, those with higher KPNA2 expression had a lower survival rate. (3) The major mutation type of KPNA2 in breast cancer samples was missense mutation. (4) Homer1 was able to promote breast cancer progression may be through upregulating TPX2 expression.

Conclusion

Our findings suggest that aberrant DNA hypomethylation of promoter regions contributes to the aberrant expression of KPNA2 in breast cancer, which might be a potential indicator of poor prognosis.

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.

IRF1 Negatively Regulates Oncogenic KPNA2 Expression Under Growth Stimulation and Hypoxia in Lung Cancer Cells

Purpose

Karyopherin alpha 2 (KPNA2) has been reported as an oncogenic protein in numerous human cancers and is currently considered a potential therapeutic target. However, the transcriptional regulation and physiological conditions underlying KPNA2 expression remain unclear. The aim of the present study was to investigate the role and regulation of interferon regulatory factor-1 (IRF1) in modulating KPNA2 expression in lung adenocarcinoma (ADC).

Materials and methods

Bioinformatics tools and chromatin immunoprecipitation were used to analyze the transcription factor (TF) binding sites in the KPNA2 promoter region. We searched for a potential role of IRF1 in non-small-cell lung cancer (NSCLC) using Oncomine and Kaplan-Meier Plotter datasets. qRT-PCR was applied to examine the role of IRF1 and signaling involved in regulating KPNA2 transcription. Western blotting was used to determine the effects of extracellular stimulation and intracellular signaling on the modulation of KPNA2-related TF expression.

Results

IRF1 was identified as a novel TF that suppresses KPNA2 gene expression. We observed that IRF1 expression was lower in cancerous tissues than in normal lung tissues and that its low expression was correlated with poor prognosis in NSCLC. Notably, both ataxia telangiectasia mutated (ATM) and mechanistic target of rapamycin (mTOR) inhibitors reduced KPNA2 expression, which was accompanied by increased expression of IRF1 but decreased expression of E2F1, a TF that promotes KPNA2 expression in lung ADC cells. IRF1 knockdown restored the reduced levels of KPNA2 in ATM inhibitor-treated cells. We further demonstrated that epidermal growth factor (EGF)-activated mTOR and hypoxia-induced ATM suppressed IRF1 expression but promoted E2F1 expression, which in turn upregulated KPNA2 expression in lung ADC cells.

Conclusion

IRF1 acts as a potential tumor suppressor in NSCLC. EGF and hypoxia promote KPNA2 expression by simultaneously suppressing IRF1 expression and enhancing E2F1 expression in lung ADC cells. Our study provides new insights into targeted therapy for lung cancer.

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.

Amino Acid Deprivation-Induced Autophagy Requires Upregulation of DIRAS3 through Reduction of E2F1 and E2F4 Transcriptional Repression

Failure to cure ovarian cancer relates to the persistence of dormant, drug-resistant cancer cells following surgery and chemotherapy. “Second look” surgery can detect small, poorly vascularized nodules of persistent ovarian cancer in ~50% of patients, where >80% are undergoing autophagy and express DIRAS3. Autophagy is one mechanism by which dormant cancer cells survive in nutrient poor environments. DIRAS3 is a tumor suppressor gene downregulated in >60% of primary ovarian cancers by genetic, epigenetic, transcriptional and post-transcriptional mechanisms, that upon re-expression can induce autophagy and dormancy in a xenograft model of ovarian cancer. We examined the expression of DIRAS3 and autophagy in ovarian cancer cells following nutrient deprivation and the mechanism by which they are upregulated. We have found that DIRAS3 mediates autophagy induced by amino acid starvation, where nutrient sensing by mTOR plays a central role. Withdrawal of amino acids downregulates mTOR, decreases binding of E2F1/4 to the DIRAS3 promoter, upregulates DIRAS3 and induces autophagy. By contrast, acute amino acid deprivation did not affect epigenetic regulation of DIRAS3 or expression of miRNAs that regulate DIRAS3. Under nutrient poor conditions DIRAS3 can be transcriptionally upregulated, inducing autophagy that could sustain dormant ovarian cancer cells.

MicroRNA-100 suppresses human osteosarcoma cell proliferation and chemo-resistance via ZNRF2

Osteosarcoma (OS) is a prevalent cancer worldwide. MicroRNAs (miRNAs) play critical roles in the growth, invasion and carcinogenesis of OS, whereas the underlying mechanisms remain ill-defined. Here, we addressed these questions. We detected significantly higher levels of ZNRF2, a ubiquitin ligase of the RING superfamily, and significantly lower levels of miR-100 in the OS specimens, compared to the paired normal bone tissues. The levels of ZNRF2 and miR-100 inversely correlated in the OS specimens. In addition, low miR-100 levels are associated with poor prognosis of the OS patients. Either ZNRF2 overexpression or miR-100 depletion increased in vitro OS cell growth and improved cell survival at the presence of Doxorubicin. Mechanistically, with the help of bioinformatics analysis and luciferase-reporter assay, we found that miR-100 might bind to the 3’-UTR of ZNRF2 mRNA to prevent its protein translation. Thus, our data suggest that re-expression of miR-100 may inhibit OS cell growth and decrease OS cell chemo-resistance.

Aberrant expression of KPNA2 is associated with a poor prognosis and contributes to OCT4 nuclear transportation in bladder cancer

Recent studies show that Karyopherin alpha 2 (KPNA2) is up-regulated in quite a number of cancers and associated with poor prognosis. Here, we found that expression levels of KPNA2 and OCT4 are up-regulated in bladder cancer tissues and significantly associated with primary tumor stage and bladder cancer patients' poorer prognosis. Our data also showed decreased cell proliferation and migration rates of bladder cancer cell lines when the expression of KPNA2 and OCT4 was silenced. Meanwhile, cell apoptosis rate was increased. Furthermore, Co-IP and immunofluorescence assay showed the KPNA2 interacts with OCT4 and inhibits OCT4 nuclear transportation when KPNA2 was silenced. Thus, we confirmed that up-regulated KPNA2 and OCT4 expression is a common feature of bladder cancer that is correlated with increased aggressive tumor behavior. Also, we propose that KPNA2 regulates the process of OCT4 nuclear transportation in bladder cancer.

High Kpnβ1 expression promotes non-small cell lung cancer proliferation and chemoresistance via the PI3-kinase/AKT pathway

Karyopherin β1 (Kpnβ1), also known as importin-β, is part of the karyopherin superfamily of nuclear transport proteins. Kpnβ1 is an oncogene that is overexpressed in various human cancers. Recent studies have showed that Kpnβ1 is one of the leading causes of cancer-related deaths in the world. However, the role of Kpnβ1 in non-small cell lung cancer (NSCLC) remains uncertain. In this study, we used western blotting to show that Kpnβ1 expression is higher in lung-cancer tissues and cells, and immunohistochemistry analysis revealed that Kpnβ1 was significantly associated with the clinicopathological features of NSCLC. Kaplan-Meier analysis showed that elevated Kpnβ1 expression correlated with a poor prognosis in NSCLC patients. Serum starvation-refeeding experiments and Kpnβ1-shRNA transfection assays revealed that elevated Kpnβ1 expression promoted cell proliferation and reduced sensitivity to cis-diamminedichloroplatinum. Immunoprecipitation assays showed that Kpnβ1 interacts with PI3 K to activate the PI3-kinase/AKT pathway, leading to enhanced cell survival and drug resistance in NSCLC cells. Collectively, our findings suggest that Kpnβ1 plays a significant role in NSCLC progression and chemoresistance. Our study provides new insights for targeted therapy to treat NSCLC.