Increased Expression of CD81 in Breast Cancer Tissue is Associated with Reduced Patient Prognosis and Increased Cell Migration and Proliferation in MDA-MB-231 and MDA-MB-435S Human Breast Cancer Cell Lines In Vitro

The molecular mechanism of CD81 antibody inhibition of metastasis

Metastases are reduced in CD81KO mice. In addition, a unique anti-CD81 antibody, 5A6, inhibits metastasis in vivo and invasion and migration in vitro. Here, we probed the structural components of CD81 required for the antimetastatic activity induced by 5A6. We found that the removal of either cholesterol or the intracellular domains of CD81 did not affect inhibition by the antibody. We show that the uniqueness of 5A6 is due not to increased affinity but rather to its recognition of a specific epitope on the large extracellular loop of CD81. Finally, we present a number of CD81 membrane-associated partners that may play a role in mediating the 5A6 antimetastatic attributes, including integrins and transferrin receptors.

Identifying signatures of EV secretion in metastatic breast cancer through functional single-cell profiling

Extracellular vesicles (EVs) regulate the tumor microenvironment by facilitating transport of biomolecules. Despite extensive investigation, heterogeneity in EV secretion among cancer cells and the mechanisms that support EV secretion are not well characterized. We developed an integrated method to identify individual cells with differences in EV secretion and performed linked single-cell RNA-sequencing on cloned single cells from the metastatic breast cancer cells. Differential gene expression analyses identified a four-gene signature of breast cancer EV secretion: HSP90AA1, HSPH1, EIF5, and DIAPH3. We functionally validated this gene signature by testing it across cell lines with different metastatic potential in vitro. Analysis of the TCGA and METABRIC datasets showed that this signature is associated with poor survival, invasive breast cancer types, and poor CD8⁺ T cell infiltration in human tumors. We anticipate that our method for directly identifying the molecular determinants of EV secretion will have broad applications across cell types and diseases.

Screening of EWI-2-Derived Peptides for Targeting Tetraspanin CD81 and Their Effect on Cancer Cell Migration

CD81, a transmembrane protein belonging to the tetraspanin family, has recently been suggested as a therapeutic target for cancers. Here, we screened peptides that bind to the tetraspanin CD81 protein, and evaluated their inhibitory activity in cancer cell migration. To screen for CD81-binding peptides (CD81-BP), a peptide array membrane was prepared from the amino acid sequence of the EWI-2 protein, a major partner of CD81, before binding to fluorescently labeled CD81. As a result, four candidate CD81-BPs were identified and characterized. In particular, the CFMKRLRK peptide (called P152 in this study) was found to be the best candidate that preferentially binds to the extracellular loop of CD81, with an estimated dissociation constant of 0.91 µM. Since CD81 was reported to promote cancer cell migration, an initial step in metastasis, the Boyden chamber assay, was next performed to assess the effect of CD81-BP candidates on the migration of MDA-MB-231 human breast cancer cells. Interestingly, our result indicated that P152 could suppress MDA-MB-231 cell migration at the level comparable to that of an anti-human CD81 antibody (5A6). Thus, we propose these CD81-BPs with the anti-migration property against cancer cells for the development of novel therapeutic strategies.

Advances in exosome analysis

There is growing demand for novel biomarkers that detect early stage disease as well as monitor clinical management and therapeutic strategies. Exosome analysis could provide the next advance in attaining that goal. Exosomes are membrane encapsulated biologic nanometric-sized particles of endocytic origin which are released by all cell types. Unfortunately, exosomes are exceptionally challenging to characterize with current technologies. Exosomes are between 30 and 200nm in diameter, a size that makes them out of the sensitivity range to most cell-oriented sorting or analysis platforms, i.e., traditional flow cytometers. The most common methods for targeting exosomes to date typically involve purification followed by the characterization and the specific determination of their cargo. The whole procedure is time consuming, requiring thus skilled personnel as well as laboratory facilities and benchtop instrumentation. The most relevant methodology for exosome isolation, characterization and quantification is addressed in this chapter, including the most up-to-date approaches to explore the potential usefulness of exosomes as biomarkers in liquid biopsies and in advanced nanomedicine.

Prolonged Exposure to Simulated Microgravity Changes Release of Small Extracellular Vesicle in Breast Cancer Cells

Breast cancer is the leading cause of cancer incidence worldwide and among the five leading causes of cancer mortality. Despite major improvements in early detection and new treatment approaches, the need for better outcomes and quality of life for patients is still high. Extracellular vesicles play an important role in tumor biology, as they are able to transfer information between cells of different origins and locations. Their potential value as biomarkers or for targeted tumor therapy is apparent. In this study, we analyzed the supernatants of MCF-7 breast cancer cells, which were harvested following 5 or 10 days of simulated microgravity on a Random Positioning Machine (RPM). The primary results showed a substantial increase in released vesicles following incubation under simulated microgravity at both time points. The distribution of subpopulations regarding their surface protein expression is also altered; the minimal changes between the time points hint at an early adaption. This is the first step in gaining further insight into the mechanisms of tumor progression, metastasis, the education of the tumor microenvironments, and preparation of the metastatic niche. Additionally, this may lighten up the processes of the rapid cellular adaptions in the organisms of space travelers during spaceflights.

Identification of active components in Andrographis paniculata targeting on CD81 in esophageal cancer in vitro and in vivo

BACKGROUND

Esophageal cancer (EC) is highly prevalent in Eastern Asia (including China) with high rates of mortality. The metastatic tendency in EC is associated with a poor prognosis. Our previous studies have demonstrated the suppressive effects of Andrographis paniculata water extract (APW) on metastatic esophageal cancer in vitro and in tumor-bearing mice models, as well as illustrated the potential underlying mechanism by transcriptome analysis.

HYPOTHESIS

High expressions of several membrane protein tetraspanins were reported to lead to a high risk of metastasis in esophageal cancer in patients. We hypothesized that APW could downregulate the expression of tetraspanin CD81 in esophageal cancer cells and xenografts.

METHODS

Human esophageal cancer cells EC109 and KYSE520 were incubated with APW for 24 hours in cell culture, while mice bearing EC109 xenograft tumors were treated with APW for 21 days. The expressions of CD81 in cancer cells and in tumors from mice were evaluated. Molecular docking and microscale thermophoresis analyses were applied to identify the components in APW interacting with CD81. The influence of the identified components on CD81 expression was further evaluated in EC109 cells.

RESULTS

APW could significantly suppress the expressions of CD81 in both EC109 and KYSE520 cells in a concentration-dependent manner. Treatment of APW in xenograft-bearing mice reduces the metastasis in lungs, livers, and lymph nodes. The expression of CD81 in xenograft tumors of APW-treated mice was significantly lower than those of untreated control mice. The binding of andrographolide, bisandrographolide A, and bisandrographolide C with CD81 were elucidated by microscale thermophoresis. The suppressive effects of these compounds on the motility of EC109 cells, as well as CD81 protein and mRNA expressions, were further confirmed.

CONCLUSION

This is the first time to demonstrate that andrographolide, bisandrographolide A, and bisandrographolide C, which are present in APW, bind to CD81 and suppress its function. These compounds are likely to be responsible for the anti-metastatic activities of APW in esophageal cancer.

Tetraspanins: Host Factors in Viral Infections

Tetraspanins are transmembrane glycoproteins that have been shown increasing interest as host factors in infectious diseases. In particular, they were implicated in the pathogenesis of both non-enveloped (human papillomavirus (HPV)) and enveloped (human immunodeficiency virus (HIV), Zika, influenza A virus, (IAV), and coronavirus) viruses through multiple stages of infection, from the initial cell membrane attachment to the syncytium formation and viral particle release. However, the mechanisms by which different tetraspanins mediate their effects vary. This review aimed to compare and contrast the role of tetraspanins in the life cycles of HPV, HIV, Zika, IAV, and coronavirus viruses, which cause the most significant health and economic burdens to society. In doing so, a better understanding of the relative contribution of tetraspanins in virus infection will allow for a more targeted approach in the treatment of these diseases.

Single-Cell Cloning of Breast Cancer Cells Secreting Specific Subsets of Extracellular Vesicles

Simple Summary

Extracellular vesicles (EVs) are a pivotal mechanism for long-distance intercellular communication and facilitate the stable transport of biological information. Conventional methods for profiling EVs are focused on the biological cargo obtained from large populations of cells and cannot map the secretion of specific subsets of EVs onto their cell of origin. We developed a high-throughput single-cell cloning method that can identify the kinetics of secretion of specific subsets of EVs. With the aid of this methodology, we illustrate that secretion of specific subsets of EVs can be an inheritable property of cancer cells. Our single-cell methodology enables the direct integration of EV secretion with multiple cellular functions and can enable new insights into cell and disease biology.

Abstract

Extracellular vesicles (EVs) mediate communication in health and disease. Conventional assays are limited in profiling EVs secreted from large populations of cells and cannot map EV secretion onto individual cells and their functional profiles. We developed a high-throughput single-cell technique that enabled the mapping of dynamics of EV secretion. By utilizing breast cancer cell lines, we established that EV secretion is heterogeneous at the single-cell level and that non-metastatic cancer cells can secrete specific subsets of EVs. Single-cell RNA sequencing confirmed that pathways related to EV secretion were enriched in the non-metastatic cells compared with metastatic cells. We established isogenic clonal cell lines from non-metastatic cells with differing propensities for CD81⁺CD63⁺EV secretion and showed for the first time that specificity in EV secretion is an inheritable property preserved during cell division. Combined in vitro and animal studies with these cell lines suggested that CD81⁺CD63⁺EV secretion can impede tumor formation. In human non-metastatic breast tumors, tumors enriched in signatures of CD81⁺CD63⁺EV have a better prognosis, higher immune cytolytic activity, and enrichment of pro-inflammatory macrophages compared with tumors with low CD81⁺CD63⁺EVs signatures. Our single-cell methodology enables the direct integration of EV secretion with multiple cellular functions and enables new insights into cell/disease biology.

Changes in protein expression due to metformin treatment and hyperinsulinemia in a human endometrial cancer cell line

The incidence of endometrial cancer (EC) has increased over the past years and mainly affects women above the age of 45 years. Metabolic diseases such as obesity and type II diabetes mellitus as well as associated conditions like polycystic ovary syndrome (PCOS), insulin resistance and hyperinsulinemia lead to elevated levels of circulating estrogens. Increased estrogen concentrations, in turn, further trigger the proliferation of endometrial cells and thus promote EC development and progression, especially in the absence of progesterone as seen in postmenopausal women. Elevated blood glucose levels in diabetic patients further contribute to the risk of EC development. Metformin is an insulin-sensitizing biguanide drug, commonly used in the treatment of type II diabetes mellitus, especially in obese patients. Besides its effects on glucose metabolism, metformin displayed anti-cancer effects in various cancer types, including EC. Direct anti-cancer effects of metformin target signaling pathways that are involved in cellular growth and proliferation, e.g. the AKT/PKB/mTOR pathway. Further proteins and pathways have been suggested as potential targets, but the underlying mechanism of action of metformin's anti-cancer activity is still not completely understood. In the present study, the effects of metformin on protein expression were investigated in the human EC cell line HEC-1A using an affinity proteomic approach. Cells were treated with 0.5 mmol/L metformin over a period of 7 days and changes in the expression pattern of 1,300 different proteins were compared to the expression in untreated control cells as well as insulin-treated cells. Insulin treatment (100 ng/mL) was incorporated into the study in order to implement a model for insulin resistance and associated hyperinsulinemia, conditions that are often observed in obese and diabetic patients. Furthermore, the culture medium was supplemented with 10 nmol/L ß-estradiol (E2) during treatments to mimic increased estrogen levels, a common risk factor for EC development. Based on the most prominent and significant changes in expression, a set of 80 proteins was selected and subjected to a more detailed analysis. The data revealed that metformin and insulin targeted similar pathways in the present study and mostly acted on proteins related to proliferation, migration and tumor immune response. These pathways may be affected in a tumor-promoting as well as a tumor-suppressing way by either metformin treatment or insulin supplementation. The consequences for the cells resulting from the detected expression changes were discussed in detail for several proteins. The presented data helps identify potential targets affected by metformin treatment in EC and allows for a better understanding of the mechanism of action of the biguanide drug's anti-cancer activity. However, further investigations are necessary to confirm the observations and conclusions drawn from the presented data after metformin administration, especially for proteins that were regulated in a favorable way, i.e. AKT3, CCND2, CD63, CD81, GFAP, IL5, IL17A, IRF4, PI3, and VTCN1. Further proteins might be of interest, where metformin counteracted unfavorable effects that have been induced by hyperinsulinemia.

SHP-2 Interacts with CD81 and Regulates the Malignant Evolution of Colorectal Cancer by Inhibiting Epithelial-Mesenchymal Transition

PURPOSE

Colon cancer is a common malignant tumor of the digestive system. This project verified the negative role of protein tyrosine phosphatase (SHP-2) in the regulation of colon cancer and further clarified the key targets and molecular mechanisms in the regulation process.

PATIENTS AND METHODS

The expression levels of SHP-2 in colon cancer tissues, adjacent tissues, normal colon cell lines, and cancer cell lines were detected via Quantitative Real-time PCR (qRT-PCR). The effect of SHP-2 on colon cancer cell function was verified using cell proliferation, Transwell, scratch, and apoptotic assays. CD81 was identified as the interaction protein of SHP-2 by immunoprecipitation.

RESULTS

The expression of SHP-2 was decreased in colorectal cancer compared with that in adjacent tissues. This expression was also decreased in colon cancer cells compared with that in intestinal epithelial cells. In addition, the tumor tissues of patients with metastatic colon cancer exhibited downregulated expression of SHP-2 compared with those of patients with non-metastatic colon cancer. Cell proliferation, Transwell, scratch, and apoptotic assay showed that the overexpression of SHP-2 inhibited proliferation, adhesion, and metastasis of colon cancer cell lines and promoted apoptosis. CO-IP proved that SHP-2 could interact with CD81 and inhibit the function of CD81. Recovery experiments confirmed that the overexpression of CD81 reversed the anti-cancer effect of SHP-2.

CONCLUSION

Overexpression of SHP-2 inhibited malignant progression of colon cancer. Mechanism experiments showed that the anti-cancer effect of SHP-2 was realized through the interaction with CD81. This study elucidated the molecular mechanism of SHP-2 regulation in colon cancer and provided guidance for the diagnosis and prognosis assessment of colon cancer.

Dysregulation of TLR2 Serves as a Prognostic Biomarker in Breast Cancer and Predicts Resistance to Endocrine Therapy in the Luminal B Subtype

Background: Breast cancer (BCa) is a serious global health burden among females, and the development of resistance represents an important challenge to BCa treatment. Here, we examined the expression of toll-like receptor 2 (TLR2) in BCa patients and the prognostic value of TLR2 for predicting endocrine resistance.

Methods: The study included 150 BCa patients, of which 82 underwent endocrine therapy. TLR2 mRNA expression was measured by quantitative Real-Time PCR, and its prognostic value was determined by Kaplan-Meier survival analysis. Changes in the expression of TLR2 in BCa patients with endocrine resistance were assessed, and the value of TLR2 for predicting endocrine resistance was evaluated using the receiver operating characteristic curve analysis.

Results: TLR2 expression was higher in BCa tissue than in normal tissue and associated with tumor size, HER2 status, tumor subtype, and TNM stage. TLR2 upregulation was associated with poor prognosis in patients with BCa, as well as endocrine resistance, and TLR2 upregulation was more prevalent among HER2-positive BCa cases. The predictive performance of TLR2 for endocrine resistance was higher in HER2-positive BCa than in other hormone receptor-positive BCa cases.

Conclusion: TLR2 upregulation is a promising biomarker for prognosis and predicting resistance to endocrine therapy. The relationship between TLR2 and HER2 indicates that TLR2 may be involved in endocrine resistance through the HER2 signaling pathway in BCa.

TSPAN8 as a Novel Emerging Therapeutic Target in Cancer for Monoclonal Antibody Therapy

Tetraspanin 8 (TSPAN8) is a member of the tetraspanin superfamily that forms TSPAN8-mediated protein complexes by interacting with themselves and other various cellular signaling molecules. These protein complexes help build tetraspanin-enriched microdomains (TEMs) that efficiently mediate intracellular signal transduction. In physiological conditions, TSPAN8 plays a vital role in the regulation of biological functions, including leukocyte trafficking, angiogenesis and wound repair. Recently, reports have increasingly shown the functional role and clinical relevance of TSPAN8 overexpression in the progression and metastasis of several cancers. In this review, we will highlight the physiological and pathophysiological roles of TSPAN8 in normal and cancer cells. Additionally, we will cover the current status of monoclonal antibodies specifically targeting TSPAN8 and the importance of TSPAN8 as an emerging therapeutic target in cancers for monoclonal antibody therapy.

Matrix Effect in the Isolation of Breast Cancer-Derived Nanovesicles by Immunomagnetic Separation and Electrochemical Immunosensing-A Comparative Study

Exosomes are cell-derived nanovesicles released into biological fluids, which are involved in cell-to-cell communication. The analysis of the content and the surface of the exosomes allow conclusions about the cells they are originating from and the underlying condition, pathology or disease. Therefore, the exosomes are currently considered good candidates as biomarkers to improve the current methods for clinical diagnosis, including cancer. However, due to their low concentration, conventional procedures for exosome detection including biosensing usually require relatively large sample volumes and involve preliminary purification and preconcentration steps by ultracentrifugation. In this paper, the immunomagnetic separation is presented as an alternative method for the specific isolation of exosomes in serum. To achieve that, a rational study of the surface proteins in exosomes, which can be recognized by magnetic particles, is presented. The characterization was performed in exosomes obtained from cell culture supernatants of MCF7, MDA-MB-231 and SKBR3 breast cancer cell lines, including TEM and nanoparticle tracking analysis (NTA). For the specific characterization by flow cytometry and confocal microscopy, different commercial antibodies against selected receptors were used, including the general tetraspanins CD9, CD63 and CD81, and cancer-related receptors (CD24, CD44, CD54, CD326 and CD340). The effect of the serum matrix on the immunomagnetic separation was then carefully evaluated by spiking the exosomes in depleted human serum. Based on this study, the exosomes were preconcentrated by immunomagnetic separation on antiCD81-modified magnetic particles in order to achieve further magnetic actuation on the surface of the electrode for the electrochemical readout. The performance of this approach is discussed and compared with classical characterization methods.

Exosome aggregation mediated stop-flow paper-based portable device for rapid exosome quantification

Exosome quantification is important for estimation of informative messengers (e.g., proteins, lipids, RNA, etc.) involving physiological and pathological effects. This work aimed to develop a simple and rapid distance-based paper portable device using exosome-capture vesicles (polydiacetylene conjugated with antiCD81) for exosome quantification in cell cultures. This novel concept relied on distinct aggregation of exosomes and exosome-capture vesicles leading to different solvent migration. Distances of the migration were used as signal readouts, which could be detected by naked eye. PDA-antiCD81 as exosome-capture vesicles were optimized (e.g., size, reaction ratio, and concentration) and the paper designs were investigated (e.g., diameter of sample reservoir and lamination layer) to enhance the solvent stop-flow effects. Finally, exosome screening on three cell culture samples (COLO1, MDA-MB-231, and HuR-KO1 subclone) was demonstrated. The method could linearly measure exosome concentrations in correlation with solvent migration distances in the range of 10⁶ -10¹⁰ particles/mL (R²  > 0.98) from the cell culture samples. The exosome concentration measurements by the developed device were independently assessed by nanoparticle tracking analysis. Results demonstrated no statistically significant difference (p > 0.05) by t-test. This low-cost and rapid device allows a portable platform for exosome quantification without the requirement of expensive equipment and expertise of operation. The developed device could potentially be useful for quantification of other biomarker-related extracellular vesicles.

Increased expression of CD81 is associated with poor prognosis of prostate cancer and increases the progression of prostate cancer cells in vitro

CD81, a member of the tetraspanin family, has been revealed to be upregulated and associated with prognosis in several types of cancer; however, this relationship has not been explored in prostate cancer. The present study aimed to investigate the prognostic significance and functional role of CD81 in prostate cancer. The expression of CD81 in prostate cancer tissues and cell lines was evaluated using qRT-PCR analysis. Kaplan-Meier survival analysis and Cox regression analysis were conducted to explore the prognostic significance of CD81. Cell experiments were used to explore the effects of CD81 on cell proliferation, migration, and invasion in prostate cell lines in vitro. The expression of CD81 was increased in both prostate cancer tissues and cell lines. Upregulation of CD81 was significantly associated with lymph node metastasis and TNM stage. Moreover, patients with high CD81 levels had poorer overall survival than those with lower levels. Additionally, tumor cell proliferation, migration, and invasion were inhibited by knockdown of CD81. The present results indicated that CD81 plays an oncogenic role in prostate cancer. Overexpression of CD81 may serve as a prognostic biomarker and therapeutic target and is involved in the progression of prostate cancer.

Proteomic Comparison of Malignant Human Germ Cell Tumor Cell Lines

Malignant germ cell tumors (GCT) are the most common malignant tumors in young men between 18 and 40 years. The correct identification of histological subtypes, in difficult cases supported by immunohistochemistry, is essential for therapeutic management. Furthermore, biomarkers may help to understand pathophysiological processes in these tumor types. Two GCT cell lines, TCam-2 with seminoma-like characteristics, and NTERA-2, an embryonal carcinoma-like cell line, were compared by a quantitative proteomic approach using high-resolution mass spectrometry (MS) in combination with stable isotope labelling by amino acid in cell culture (SILAC). We were able to identify 4856 proteins and quantify the expression of 3936. 347 were significantly differentially expressed between the two cell lines. For further validation, CD81, CBX-3, PHF6, and ENSA were analyzed by western blot analysis. The results confirmed the MS results. Immunohistochemical analysis on 59 formalin-fixed and paraffin-embedded (FFPE) normal and GCT tissue samples (normal testis, GCNIS, seminomas, and embryonal carcinomas) of these proteins demonstrated the ability to distinguish different GCT subtypes, especially seminomas and embryonal carcinomas. In addition, siRNA-mediated knockdown of these proteins resulted in an antiproliferative effect in TCam-2, NTERA-2, and an additional embryonal carcinoma-like cell line, NCCIT. In summary, this study represents a proteomic resource for the discrimination of malignant germ cell tumor subtypes and the observed antiproliferative effect after knockdown of selected proteins paves the way for the identification of new potential drug targets.

Systems-level Analysis Reveals Multiple Modulators of Epithelial-mesenchymal Transition and Identifies DNAJB4 and CD81 as Novel Metastasis Inducers in Breast Cancer

Epithelial-mesenchymal transition (EMT) is driven by complex signaling events that induce dramatic biochemical and morphological changes whereby epithelial cells are converted into cancer cells. However, the underlying molecular mechanisms remain elusive. Here, we used mass spectrometry based quantitative proteomics approach to systematically analyze the post-translational biochemical changes that drive differentiation of human mammary epithelial (HMLE) cells into mesenchymal. We identified 314 proteins out of more than 6,000 unique proteins and 871 phosphopeptides out of more than 7,000 unique phosphopeptides as differentially regulated. We found that phosphoproteome is more unstable and prone to changes during EMT compared with the proteome and multiple alterations at proteome level are not thoroughly represented by transcriptional data highlighting the necessity of proteome level analysis. We discovered cell state specific signaling pathways, such as Hippo, sphingolipid signaling, and unfolded protein response (UPR) by modeling the networks of regulated proteins and potential kinase-substrate groups. We identified two novel factors for EMT whose expression increased on EMT induction: DnaJ heat shock protein family (Hsp40) member B4 (DNAJB4) and cluster of differentiation 81 (CD81). Suppression of DNAJB4 or CD81 in mesenchymal breast cancer cells resulted in decreased cell migration in vitro and led to reduced primary tumor growth, extravasation, and lung metastasis in vivo Overall, we performed the global proteomic and phosphoproteomic analyses of EMT, identified and validated new mRNA and/or protein level modulators of EMT. This work also provides a unique platform and resource for future studies focusing on metastasis and drug resistance.

Suppression of CD81 promotes bladder cancer cell invasion through increased matrix metalloproteinase expression via extracellular signal-regulated kinase phosphorylation

Purpose

CD81 is a prognostic biomarker for high-grade bladder cancer (BC). In this study, we aimed to determine the functional mechanisms underlying the role of CD81 in BC progression.

Materials and Methods

In two invasive BC cell lines (T24, J82), CD81 expression was suppressed by the transfection of lentiviral vectors including CD81-specific shRNAs, and then the migration and invasion of BC cells was analyzed. Enzymatic activity of matrix metalloproteinases (MMPs) was also analyzed by collagen-zymography. The expression of MMPs was confirmed by western blotting using culture supernatants from each cell line. Signaling pathways related to MMPs were investigated using various antibodies.

Results

CD81 was successfully knocked down by shRNAs in T24 and J82 cell lines. While the migration of BC cells was not affected after the knockdown of CD81, the invasive activity was significantly increased in both cell lines. Zymography produced distinct bands using supernatants from CD81-knockdown cells, whereas only faint bands were observed with empty vector-transfected cells. We also observed an increased expression of MMPs, specifically MMP2 and 9, in the conditioned media from CD81-knockdown cells by western blotting. Mechanistically, the phosphorylation of extracellular signal-regulated kinase (ERK) was associated with the invasive activity of BC cells, while U0126 (an ERK inhibitor) reduced the invasive activity of CD81-knockdown BC cells.

Conclusions

Taken together, CD81 suppression promotes the invasive property of BC cells through MMP signaling via ERK phosphorylation. Our results suggest that the regulation of CD81 expression may have some therapeutic potential in BC.

Actinin-4 as a Diagnostic Biomarker in Serum of Breast Cancer Patients

Background

α-actinin-4 (Actinin-4 or ACTN4), originally identified as an actin-binding protein associated with the biological function of cancer cells, appears to be highly expressed in numerous human epithelial carcinomas, including breast cancer (BC). In the present study we assessed the role of serum ACTN4 as a biomarker for BC diagnosis, as well as the association between ACTN4 levels and clinicopathological features.

Material/Methods

ACTN4 expression level was measured with quantitative real-time PCR (qRT-PCR) analysis in serum specimens of 128 BC patients and 96 healthy volunteers. χ² testing was conducted to explore the association of ACTN4 levels with clinicopathologic factors. Moreover, the diagnostic value of ACTN4 was analyzed using receiver operating characteristic (ROC) curves.

Results

Serum ACTN4 level was obviously upregulated in patients with BC compared with healthy controls (P<0.05). High ACTN4 expression was significantly associated with clinical stage (P=0.000), tumor grade (P=0.004), and lymph node status (P=0.024). However, no association was found between ACTN4 expression and age, tumor size, ER status, PR status, or HER-2 status (all P>0.05). The ROC analysis showed that the area under the curve (AUC) of ACTN4 was 0.887 (95%CI: 0.843–0.931), with sensitivity of 80.5% and specificity of 84.4%, and the cutoff value was 1.050.

Conclusions

ACTN4 in serum can serve as a clinical predictor in the diagnosis or prediction of clinical outcomes of patients with BC.

Distinct Diagnostic and Prognostic Values of Kinesin Family Member Genes Expression in Patients with Breast Cancer

BACKGROUND This study investigated the diagnostic and prognostic values of kinesin superfamily proteins (KIFs) in breast cancer (BC) patients. MATERIAL AND METHODS All data were obtained from the Cancer Genome Atlas. DESeq was run to test for differentially expressed KIF genes. Patients were divided into high- and low-expression groups according to the median expression values of each KIF genes. Survival data were calculated using the Cox proportional hazard model. Comprehensive survival analysis was performed to evaluate the prognostic value of the prognostic signature. Gene set enrichment analysis (GSEA) was conducted to identify associated gene ontology and KEGG pathways. RESULTS Bioinformatics analysis showed that all KIF genes were significantly enriched during DNA replication and the cell cycle, and co-expressed with each other. Thirteen KIF genes were differentially expressed in cancer and adjacent tissues, and high levels of KIF15, KIF20A, KIF23, KIF2C and KIF4A genes were significantly correlated with poor overall survival (OS). GSEA showed that BC patients with high expression of KIF15, KIF20A, KIF23, KIF2C and KIF4A were enriched in the cell cycle process, P53 regulation pathway and mismatch repair. Combinations of low expression of KIF15, KIF20A, KIF23, KIF2C and KIF4A were more highly correlated with favorable OS. Nomograms showed that the KIF4A risk score provided the maximum number of risk points (range 0-100), whereas other genes made a lower contribution. CONCLUSIONS We conclude that 13 KIF genes are differentially expressed in BC tumor tissues, and KIF15, KIF20A, KIF23, KIF2C and KIF4A are associated with prognostic factors in BC.