Expression of the β3 subunit of Na+/K+-ATPase is increased in gastric cancer and regulates gastric cancer cell progression and prognosis via the PI3/AKT pathway

The role of metal ions in the occurrence, progression, drug resistance, and biological characteristics of gastric cancer

Metal ions exert pivotal functions within the human body, encompassing essential roles in upholding cell structure, gene expression regulation, and catalytic enzyme activity. Additionally, they significantly influence various pathways implicated in divergent mechanisms of cell death. Among the prevailing malignant tumors of the digestive tract worldwide, gastric cancer stands prominent, exhibiting persistent high mortality rates. A compelling body of evidence reveals conspicuous ion irregularities in tumor tissues, encompassing gastric cancer. Notably, metal ions have been observed to elicit distinct contributions to the progression, drug resistance, and biological attributes of gastric cancer. This review consolidates pertinent literature on the involvement of metal ions in the etiology and advancement of gastric cancer. Particular attention is directed towards metal ions, namely, Na, K, Mg, Ca, Fe, Cu, Zn, and Mn, elucidating their roles in the initiation and progression of gastric cancer, cellular demise processes, drug resistance phenomena, and therapeutic approaches.

Contribution of m5C RNA Modification-Related Genes to Prognosis and Immunotherapy Prediction in Patients with Ovarian Cancer

Background

5-Methylcytosine (m5C) RNA modification is closely implicated in the occurrence of a variety of cancers. Here, we established a novel prognostic signature for ovarian cancer (OC) patients based on m5C RNA modification-related genes and explored the correlation between these genes with the tumor immune microenvironment.

Methods

Methylated-RNA immunoprecipitation sequencing helped us to identify candidate genes related to m5C RNA modification at first. Based on TCGA database, we screened the differentially expressed candidate genes related to the prognosis and constructed a prognostic model using LASSO Cox regression analyses. Notably, the accuracy of the model was evaluated by Kaplan-Meier analysis and receiver operator characteristic curves. Independent prognostic risk factors were investigated by Cox proportional hazard model. Furthermore, we also analyzed the biological functions and pathways involved in the signature. Finally, the immune response of the model was visualized in great detail.

Results

Totally, 2,493 candidate genes proved to be involved in m5C modification of RNA for OC. We developed a signature with prognostic value consisting of six m5C RNA modification-related genes. Specially, samples have been split into two cohorts with low- and high-risk scores according to the model, in which the low-risk OC patients exhibited dramatically better overall survival time than those with high-risk scores. Besides, not only was this model a prognostic factor independent of other clinical characteristics but it predicted the intensity of the immune response in OC. Significantly, the accuracy and availability of the signature were verified by ICGC database.

Conclusions

Our study bridged the gap between m5C RNA modification and the prognosis of OC and was expected to provide an effective breakthrough for immunotherapy in OC patients.

Identification of N1 methyladenosine-related biomarker predicting overall survival outcomes and experimental verification in ovarian cancer

AIM

This study aimed to construct a N1-methyladenosine (m1A)-related biomarker model for predicting the prognosis of ovarian cancer (OVCA).

METHODS

OVCA samples were clustered into two subtypes using the Non-Negative Matrix Factorization (NMF) algorithm, including TCGA (n = 374) as the training set and GSE26712 (n = 185) as the external validation set. Hub genes, which were screened to construct a risk model, and nomogram to predict the overall survival of OVCA were explored and validated through various bioinformatic analysis and quantitative real-time PCR.

RESULTS

Following bootstrap correction, the C-index of nomogram was 0.62515, showing reliable performance. The functions of DEGs in the high- and low-risk groups were mainly enriched in immune response, immune regulation, and immune-related diseases. The immune cells relevant to the expression of hub genes were explored, for example, Natural Killer (NK) cells, T cells, activated dendritic cells (aDC).

CONCLUSIONS

AADAC, CD38, CACNA1C, and ATP1A3 might be used as m1A-related biomarkers for OVCA, and the nomogram labeled with m1A for the first time had excellent performance for predicting overall survival in OVCA.

Exploiting convergent phenotypes to derive a pan-cancer cisplatin response gene expression signature

Precision medicine offers remarkable potential for the treatment of cancer, but is largely focused on tumors that harbor actionable mutations. Gene expression signatures can expand the scope of precision medicine by predicting response to traditional (cytotoxic) chemotherapy agents without relying on changes in mutational status. We present a new signature extraction method, inspired by the principle of convergent phenotypes, which states that tumors with disparate genetic backgrounds may evolve similar phenotypes independently. This evolutionary-informed method can be utilized to produce consensus signatures predictive of response to over 200 chemotherapeutic drugs found in the Genomics of Drug Sensitivity in Cancer (GDSC) Database. Here, we demonstrate its use by extracting the Cisplatin Response Signature (CisSig). We show that this signature can predict cisplatin response within carcinoma-based cell lines from the GDSC database, and expression of the signatures aligns with clinical trends seen in independent datasets of tumor samples from The Cancer Genome Atlas (TCGA) and Total Cancer Care (TCC) database. Finally, we demonstrate preliminary validation of CisSig for use in muscle-invasive bladder cancer, predicting overall survival in a small cohort of patients who undergo cisplatin-containing chemotherapy. This methodology can be used to produce robust signatures that, with further clinical validation, may be used for the prediction of traditional chemotherapeutic response, dramatically increasing the reach of personalized medicine in cancer.

Trimethylamine-N-oxide (TMAO) mediates the crosstalk between the gut microbiota and hepatic vascular niche to alleviate liver fibrosis in nonalcoholic steatohepatitis

Liver fibrosis is one main histological characteristic of nonalcoholic steatohepatitis (NASH), a disease paralleling a worldwide surge in metabolic syndromes with no approved therapies. The role of the gut microbiota in NASH pathogenesis has not been thoroughly illustrated, especially how the gut microbiota derives metabolites to influence the distal liver in NASH. Here, we performed 16S rDNA amplicon sequencing analysis of feces from a mouse NASH model induced by a Western diet and CCl4 injury and found genera under Streptococcaceae, Alcaligenaceae, Oscillibacter, and Pseudochrobactrum, which are related metabolites of TMAO. Injection of the gut microbial metabolite TMAO reduced the progression of liver fibrosis in the mouse NASH model. Further analysis revealed that the anti-fibrotic TMAO normalized gut microbiota diversity and preserved liver sinusoidal endothelial cell integrity by inhibiting endothelial beta 1-subunit of Na (+), K (+)-ATPase (ATP1B1) expression. Collectively, our findings suggest TMAO-mediated crosstalk between microbiota metabolites and hepatic vasculature, and perturbation of this crosstalk disrupts sinusoidal vasculature to promote liver fibrosis in NASH.

Na+/K+ ATPase α1 and β3 subunits are localized to the basolateral membrane of trophectoderm cells in human blastocysts

STUDY QUESTION

Is there a relation between specific Na+/K+ ATPase isoform expression and localization in human blastocysts and the developmental behavior of the embryo?

SUMMARY ANSWER

Na+/K+ ATPase α1, β1 and β3 are the main isoforms expressed in human blastocysts and no association was found between the expression level of their respective mRNAs and the rate of blastocyst expansion.

WHAT IS KNOWN ALREADY

In mouse embryos, Na+/K+ ATPase α1 and β1 are expressed in the basolateral membrane of trophectoderm (TE) cells and are believed to be involved in blastocoel formation (cavitation).

STUDY DESIGN, SIZE, DURATION

A total of 20 surplus embryos from 11 patients who underwent IVF and embryo transfer at a university hospital between 2009 and 2018 were analyzed.

PARTICIPANTS/MATERIALS, SETTING, METHODS

After freezing and thawing Day 5 human blastocysts, their developmental behavior was observed for 24 h using time-lapse imaging, and the expression of Na+/K+ ATPase isoforms was examined using quantitative RT-PCR (RT-qPCR). The expressed isoforms were then localized in blastocysts using fluorescent immunostaining.

MAIN RESULTS AND THE ROLE OF CHANCE

RT-qPCR results demonstrated the expression of Na+/K+ ATPase α1, β1 and β3 isoforms in human blastocysts. Isoforms α1 and β3 were localized to the basolateral membrane of TE cells, and β1 was localized between TE cells. A high level of β3 mRNA expression correlated with easier hatching (P = 0.0261).

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

The expression of mRNA and the localization of proteins of interest were verified, but we have not been able to perform functional analysis.

WIDER IMPLICATIONS OF THE FINDINGS

Of the various Na+/K+ ATPase isoforms, expression levels of the α1, β1 and β3 mRNAs were clearly higher than other isoforms in human blastocysts. Since α1 and β3 were localized to the basolateral membrane via fluorescent immunostaining, we believe that these subunits contribute to the dilation of the blastocoel. The β1 isoform is localized between TE cells and may be involved in tight junction formation, as previously reported in mouse embryos.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the JSPS KAKENHI (https://www.jsps.go.jp/english/index.html), grant number 17K11215. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The authors have no conflicts of interest.

Tumor Tissue Oxidative Stress Changes and Na, K-ATPase Evaluation in Head and Neck Squamous Cell Carcinoma

Changes in metabolism are mechanisms that are largely implicated in the development, progression, and metastasis of head and neck squamous cell carcinoma (HNSCC) and also in resistance to different anticancer therapies. Identification of biomarkers for differentiation between cancerous and normal epithelium, treatment design and prognosis remain a vital issue in the field of head and neck cancer. The present study analyzed the main biochemical changes that occur in HNSCC tumors by through mechanisms involving oxidative stress. The release of substances reactive to thiobarbituric acid was significantly lower in HNSCC tumor tissue as compared to healthy tissue. The assays related to the lipid profile assays showed changes in membrane biophysics of tumor cells due to an increase in total phospholipids and total cholesterol, as well as an increased activity and expression of the α1 subunit of Na, K-ATPase, which is fundamental in the process of carcinogenesis. The modulation of the antioxidant system was also affected, with a decrease in the catalytic activity of the enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx), as well as a reduction of glutathione (GSH) content and an increase in H₂O₂ content. A reduction in catalase (CAT) activity was observed. The data presented here are in accordance with important findings described by us in a previous study, involving the same individuals, but with a focus on the damage generated in red blood cells, resulting from tumor installation. Therefore, it was possible to conclude that the biochemical alterations found in HNSCC cells are fundamental for transformation and maintenance of the tumor cell and once it is installed, it is also capable of generating injuries in the patients' red blood cells. Our data demonstrate that this could be a promising biomarker for HNSCC.

Integrative Transcriptomic, Proteomic and Functional Analysis Reveals ATP1B3 as a Diagnostic and Potential Therapeutic Target in Hepatocellular Carcinoma

The Na+/K+-ATPase (NKA), has been proposed as a signal transducer involving various pathobiological processes, including tumorigenesis. However, the clinical relevance of NKA in hepatocellular carcinoma (HCC) has not been well studied. This study revealed the upregulation of mRNA of ATP1A1, ATP1B1, and ATP1B3 in HCC using TCGA, ICGC, and GEO database. Subsequently, ATP1B3 was demonstrated as an independent prognostic factor of overall survival (OS) of HCC. To investigate the potential mechanisms of ATP1B3 in HCC, we analyzed the co-expression network using LinkedOmics and found that ATP1B3 co-expressed genes were associated with immune-related biological processes. Furthermore, we found that ATP1B3 was correlated immune cell infiltration and immune-related cytokines expression in HCC. The protein level of ATP1B3 was also validated as a prognostic significance and was correlated with immune infiltration in HCC using two proteomics datasets. Finally, functional analysis revealed that ATP1B3 was increased in HCC cells and tissues, silenced ATP1B3 repressed HCC cell proliferation, migration, and promoted HCC cell apoptosis and epithelial to mesenchymal transition (EMT). In conclusion, these findings proved that ATP1B3 could be an oncogene and it was demonstrated as an independent prognostic factor and correlated with immune infiltration in HCC, revealing new insights into the prognostic role and potential immune regulation of ATP1B3 in HCC progression and provide a novel possible therapeutic strategy for HCC.

Guidelines for Regulated Cell Death Assays: A Systematic Summary, A Categorical Comparison, A Prospective

Over the past few years, the field of regulated cell death continues to expand and novel mechanisms that orchestrate multiple regulated cell death pathways are being unveiled. Meanwhile, researchers are focused on targeting these regulated pathways which are closely associated with various diseases for diagnosis, treatment, and prognosis. However, the complexity of the mechanisms and the difficulties of distinguishing among various regulated types of cell death make it harder to carry out the work and delay its progression. Here, we provide a systematic guideline for the fundamental detection and distinction of the major regulated cell death pathways following morphological, biochemical, and functional perspectives. Moreover, a comprehensive evaluation of different assay methods is critically reviewed, helping researchers to make a reliable selection from among the cell death assays. Also, we highlight the recent events that have demonstrated some novel regulated cell death processes, including newly reported biomarkers (e.g., non-coding RNA, exosomes, and proteins) and detection techniques.

Targeting Ion Channels for Cancer Treatment: Current Progress and Future Challenges

Ion channels are key regulators of cancer cell pathophysiology. They contribute to a variety of processes such as maintenance of cellular osmolarity and membrane potential, motility (via interactions with the cytoskeleton), invasion, signal transduction, transcriptional activity and cell cycle progression, leading to tumour progression and metastasis. Ion channels thus represent promising targets for cancer therapy. Ion channels are attractive targets because many of them are expressed at the plasma membrane and a broad range of existing inhibitors are already in clinical use for other indications. However, many of the ion channels identified in cancer cells are also active in healthy normal cells, so there is a risk that certain blockers may have off-target effects on normal physiological function. This review describes recent research advances into ion channel inhibitors as anticancer therapeutics. A growing body of evidence suggests that a range of existing and novel Na⁺, K⁺, Ca²⁺ and Cl^- channel inhibitors may be effective for suppressing cancer cell proliferation, migration and invasion, as well as enhancing apoptosis, leading to suppression of tumour growth and metastasis, either alone or in combination with standard-of-care therapies. The majority of evidence to date is based on preclinical in vitro and in vivo studies, although there are several examples of ion channel-targeting strategies now reaching early phase clinical trials. Given the strong links between ion channel function and regulation of tumour growth, metastasis and chemotherapy resistance, it is likely that further work in this area will facilitate the development of new therapeutic approaches which will reach the clinic in the future.

Comprehensive analysis of the expression of sodium/potassium-ATPase α subunits and prognosis of ovarian serous cystadenocarcinoma

Background

Ovarian serous cystadenocarcinoma (OSC) is the most common and lethal gynecological cancer in women worldwide; however, biomarkers to diagnose and predict prognosis of OSC remain limited. Therefore, the present study aimed to investigate whether sodium/potassium adenosine triphosphate (Na⁺/K⁺-ATP)ase α-subunits (ATP1As) are helpful diagnostic and prognostic markers of OSC.

Methods

Gene expression data (RNA-Seq) of 376 patients with OSC were downloaded from The Cancer Genome Atlas (TCGA) program database. Additional databases used in our analysis included the Gene Expression Omnibus, International Cancer Genome Consortium, Genotype-Tissue Expression, the Human Protein Atlas, cBioPortal for Cancer Genomics, and Cancer Cell Line Encyclopedia.

Results

The expression levels of ATP1A1 and ATP1A3 were higher in OSC tissues than in normal ovarian tissues, whereas the expression levels of ATP1A2 and ATP1A4 were lower in OSC tissues than in normal ovarian tissues. Overexpression of ATP1A2 was significantly associated with a higher Federation of Gynecology and Obstetrics (FIGO) stage and histological grade. Increased mRNA expression of ATP1A3 was significantly associated with shorter overall survival (OS) and disease-specific survival (DSS) in patients with OSC, whereas higher expression of ATP1A4 was associated with favorable OS and DSS. Multivariate analysis showed that primary therapy outcome, residual tumor, and mRNA expressions of ATP1A3 and ATP1A4 were independent prognostic factors for both OS and DSS in patients with OSC. Moreover, ATP1A1 staining was abundant in tumor tissues. A high expression of ATP1A3 was significantly correlated with poor OS and DSS in the subgroup of patients aged ≥ 60 years and with FIGO stage III, histological grade G3, and TP53 mutation. Mutation frequencies of the ATP1As were 3–5%.

Conclusions

These results indicate that the ATP1A gene family could be potential diagnostic or prognostic markers of OSC. In addition, ATP1As may be effective therapeutic targets in the treatment of OSC.

Gene expression dynamic analysis reveals co-activation of Sonic Hedgehog and epidermal growth factor followed by dynamic silencing

Aberrant activation of the Sonic Hedgehog (SHH) gene is observed in various cancers. Previous studies have shown a “cross-talk” effect between the canonical Hedgehog signaling pathway and the Epidermal Growth Factor (EGF) pathway when SHH is active in the presence of EGF. However, the precise mechanism of the cross-talk effect on the entire gene population has not been investigated. Here, we re-analyzed publicly available data to study how SHH and EGF cooperate to affect the dynamic activity of the gene population. We used genome dynamic analysis to explore the expression profiles under different conditions in a human medulloblastoma cell line. Ordinary differential equations, equipped with solid statistical and computational tools, were exploited to extract the information hidden in the dynamic behavior of the gene population. Our results revealed that EGF stimulation plays a dominant role, overshadowing most of the SHH effects. We also identified cross-talk genes that exhibited expression profiles dissimilar to that seen under SHH or EGF stimulation alone. These unique cross-talk patterns were validated in a cell culture model. These cross-talk genes identified here may serve as valuable markers to study or test for EGF co-stimulatory effects in an SHH+ environment. Furthermore, these cross-talk genes may play roles in cancer progression, thus they may be further explored as cancer treatment targets.

Integrative proteomic and functional analyses provide novel insights into the action of the repurposed drug candidate nitroxoline in AsPC-1 cells

We recently identified nitroxoline as a repurposed drug candidate in pancreatic cancer (PC) showing a dose-dependent antiproliferative activity in different PC cell lines. This antibiotic is effective in several in vitro and animal cancer models. To date, the mechanisms of nitroxoline anticancer action are largely unknown. Using shotgun proteomics we identified 363 proteins affected by nitroxoline treatment in AsPC-1 pancreatic cancer cells, including 81 consistently deregulated at both 24- and 48-hour treatment. These proteins previously unknown to be affected by nitroxoline were mostly downregulated and interconnected in a single highly-enriched network of protein-protein interactions. Integrative proteomic and functional analyses revealed nitroxoline-induced downregulation of Na/K-ATPase pump and β-catenin, which associated with drastic impairment in cell growth, migration, invasion, increased ROS production and induction of DNA damage response. Remarkably, nitroxoline induced a previously unknown deregulation of molecules with a critical role in cell bioenergetics, which resulted in mitochondrial depolarization. Our study also suggests that deregulation of cytosolic iron homeostasis and of co-translational targeting to membrane contribute to nitroxoline anticancer action. This study broadens our understanding of the mechanisms of nitroxoline action, showing that the drug modulates multiple proteins crucial in cancer biology and previously unknown to be affected by nitroxoline.

Sodium homeostasis in the tumour microenvironment

The concentration of sodium ions (Na+) is raised in solid tumours and can be measured at the cellular, tissue and patient levels. At the cellular level, the Na+ gradient across the membrane powers the transport of H+ ions and essential nutrients for normal activity. The maintenance of the Na+ gradient requires a large proportion of the cell's ATP. Na+ is a major contributor to the osmolarity of the tumour microenvironment, which affects cell volume and metabolism as well as immune function. Here, we review evidence indicating that Na+ handling is altered in tumours, explore our current understanding of the mechanisms that may underlie these alterations and consider the potential consequences for cancer progression. Dysregulated Na+ balance in tumours may open opportunities for new imaging biomarkers and re-purposing of drugs for treatment.

Targeting β2 subunit of Na+/K+-ATPase induces glioblastoma cell apoptosis through elevation of intracellular Ca2

Glioblastoma (GBM) is the most frequent brain cancer with poor prognosis and few therapies and urgently requires effective treatments. Na+/K+-ATPase is considered as a target for GBM therapy and development of anticancer drugs. Cardiac glycosides bind the Na+/K+-ATPase α subunit to inhibit enzymatic activity and are promising candidates for anticancer drug development including GBM. However, the comparatively higher doses required for effective anticancer actions cause severe cardiotoxicity. Selectively targeting the ATPase Na+/K+ transporting subunit beta 2 (ATP1B2) that is not expressed in the heart might avoid the cardiotoxicity. However, the effect of targeting ATP1B2 in GBM remains unknown. In this study, we found that high ATP1B2 expression is significantly associated with poor prognosis of patients with GBM. ATP1B2 silencing in GBM cells resulted in remarkably cell cycle arrest at the G2/M phase and apoptosis with concomitant increase in intracellular Ca2+ and activation of p38 kinase, similar to Na+/K+-ATPase inhibition by the classic cardiac glycoside digoxin. ATP1B2 is expressed higher in glioblastoma stem-like cells (GSCs) than in GBM cells and its downregulation induces apoptosis of GSCs. Furthermore, inducible ATP1B2 knockdown significantly inhibit tumor growth in vivo. Our data suggest ATP1B2 has potential as a therapeutic target for GBM.

PI3K expression predicts overall survival in lung adenocarcinoma

BACKGROUND

Phosphoinositide 3-kinase (PI3K)/phosphorylated PI3K (p-PI3K) is considered a hallmark in tumor initiation and progression, but its prognostic value in non-small cell lung cancer (NSCLC) remains controversial.

METHODS

In the present study, we included 118 NSCLC tissue samples and 13 adjacent normal lung tissue specimens. Immunohistochemical staining was applied to test PI3K/p-PI3K expression. Pearson Chi-squared test and Kaplan-Meier curve were conducted to analyze its correlation with both clinicopathological features and prognosis in NSCLC patients.

RESULTS

PI3K/p-PI3K expression in lung cancer tissue differed significantly from that of normal lung tissue (P < 0.001). M stage was significantly correlated to PI3K expression (P = 0.037), but no significant association was found between p-PI3K expression and clinical characteristics. Neither PI3K nor p-PI3K were correlated to overall survival of NSCLC patients (P = 0.105 and P = 0.190, respectively). However, it was found in subgroup analysis that lung adenocarcinoma patients with positive PI3K expression had a favorable survival (P = 0.043). Notably, this correlation was determined invalid in subsequent multivariate analysis (P = 0.052).

CONCLUSIONS

PI3K could predict the overall survival of lung adenocarcinoma patients, but failed to be an independent prognostic predictor.

Modeling of inhomogeneous electromagnetic fields in the nervous system: a novel paradigm in understanding cell interactions, disease etiology and therapy

All major processes in the nervous system depend on interactions between cells and nerve fibers. In this work we present a novel model of inhomogeneous electromagnetic fields originating from nerve fibers and delineate their influence on cells. By expanding Hodgkin-Huxley's applied current into axial current, governed by[Formula: see text], we reveal that cell-with-neuron interactions are regulated by the strength of the electromagnetic fields, which are homogeneous up to 2.066 μm or 6.606 μm away from neurilemma and axolemma, respectively. At the nodes of Ranvier, these fields reach strengths of 3.0 × 10^-12T, while at the myelinated segments they only peak at 2.3 × 10^-12T. These are the same fields which are, due to inhomogeneity, detected as 1,000 times weaker by magnetoencephalography. Considering the widespread occurrence of neurodegenerative disorders, our model reveals that a 50% demyelination increases the field strength by 0.35 × 10^-12T, while a complete demyelination increases it by 0.7 × 10^-12T. Since this suggests that the inhomogeneous electromagnetic fields around neurons play a role in physiological and pathological processes, including cell-to-neuron and cell-to-cell communication, their improved understanding opens up new therapeutic strategies based on electromagnetic field modulation or cell's surface charge alteration.

Cardiac glycoside bufalin blocks cancer cell growth by inhibition of Aurora A and Aurora B activation via PI3K-Akt pathway

In our previous study, cardiac glycosides including bufalin, a group of sodium pump (Na+/K+-ATPase) inhibitors widely used to treat heart failure for many years, have been demonstrated to induce a delay of mitotic entry and mitotic arrest in many cancer cells. However, the underlying mechanism remains poorly understood. Here, we reported for the first time that cardiac glycoside bufalin induced mitotic entry delay and prometaphase arrest by inhibition of activation of Aurora A/B. Furthermore, cardiac glycoside bufalin prevented Aurora A recruitment to mitotic centrosomes and Aurora B recruitment to unattached kinetochores. Mechanistically, bufalin and knockdown of sodium pump inhibited PI3K-Akt pathway, which in turn inhibit the activation of Aurora A/B, followed by a delay in mitotic entry and mitotic arrest. These actions were reversed by overexpression of Akt. In addition, ERK, mTOR, and ROS are not involved in bufalin-mediated downregulation of active form of Aurora A/B. Taken together, cardiac glycoside bufalin induces mitotic entry delay and mitotic arrest in cancer cells through inhibition of Aurora A/B activation via PI3K-Akt pathway. Based on this novel finding we could suggest that targeting PI3K-Akt pathway may have therapeutic value for the treatment of cancers associated with sodium pump overexpression.