Inhibition of breast cancer cell adhesion and bone metastasis by the extracellular adherence protein of Staphylococcus aureus

Intra-tumoral bacteria in breast cancer and intervention strategies

The microbiome, consisting of a wide range of both beneficial and harmful microorganisms, is vital to various physiological and pathological processes in the human body, including cancer pathogenesis. Tumor progression is often accompanied by the destruction of the vascular system, allowing bacteria to circulate into the tumor area and flourish in an immunosuppressive environment. Microbes are recognized as significant components of the tumor microenvironment. Recent research has increasingly focused on the role of intra-tumoral bacteria in the onset, progression, and treatment of breast cancer-the most prevalent cancer among women. This review elucidates the potential mechanisms by which intra-tumoral bacteria impact breast cancer and discusses different therapeutic approaches aimed at targeting these bacteria. It provides essential insights for enhancing existing treatment paradigms while paving the way for novel anticancer interventions. As our understanding of the microbiome's intricate relationship with cancer deepens, it opens avenues for groundbreaking strategies that could redefine oncology.

Bidirectional Functional Effects of Staphylococcus on Carcinogenesis

As a Gram-positive cocci existing in nature, Staphylococcus has a variety of species, such as Staphylococcus aureus and Staphylococcus epidermidis, etc. Growing evidence reveals that Staphylococcus is closely related to the occurrence and development of various cancers. On the one hand, cancer patients are more likely to suffer from bacterial infection and antibiotic-resistant strain infection compared to healthy controls. On the other hand, there exists an association between staphylococcal infection and carcinogenesis. Staphylococcus often plays a pathogenic role and evades the host immune system through surface adhesion molecules, α-hemolysin, PVL (Panton-Valentine leukocidin), SEs (staphylococcal enterotoxins), SpA (staphylococcal protein A), TSST-1 (Toxic shock syndrom toxin-1) and other factors. Staphylococcal nucleases (SNases) are extracellular nucleases that serve as genomic markers for Staphylococcus aureus. Interestingly, a human homologue of SNases, SND1 (staphylococcal nuclease and Tudor domain-containing 1), has been recognized as an oncoprotein. This review is the first to summarize the reported basic and clinical evidence on staphylococci and neoplasms. Investigations on the correlation between Staphylococcus and the occurrence, development, diagnosis and treatment of breast, skin, oral, colon and other cancers, are made from the perspectives of various virulence factors and SND1.

Staphylococcus aureus-Derived Extracellular Vesicles Enhance the Efficacy of Endocrine Therapy in Breast Cancer Cells

The microbiome involved in the human estrogen metabolism is known as the estrobolome. This study aimed to show that the estrobolome can be used in breast cancer treatment. We first analyzed the blood microbiome composition of healthy controls and patients with breast cancer. In particular, we investigated the bacteria producing β-glucuronidase and/or β-galactosidase, which are involved in estrogen metabolism in the human body. Staphylococcus species were more abundant in healthy controls than in breast cancer patients and therefore were selected for further analyses. The effect of Staphylococcus aureus on endocrine therapy was analyzed by a combination treatment with tamoxifen. Analysis of the microbiome of blood samples showed that species producing β-glucuronidase were more abundant in breast cancer patients than in healthy controls. Further experiments confirmed that the efficacy of tamoxifen increased when administered in conjugation with the extracellular vesicles (EVs) of S. aureus. Based on our results, we deduced that S. aureus EVs could potentially be used as adjuvants for breast cancer treatment in the future.

Carcinogenic Activities and Sperm Abnormalities of Methicillin Resistance Staphylococcus aureus and Inhibition of Their Virulence Potentials by Ayamycin

This investigation aimed to study the in vivo harmful effects of the subcutaneous injection of different methicillin resistance Staphylococcus aureus extracts (MRSA2, MRSA4, MRSA10, MRSA69, MRSA70, MRSA76, and MRSA78). Such strains represented the highest minimum inhibition concentration toward methicillin with various multidrug-resistant patterns. The obtained results revealed that rats injected with the MRSA4 extract died immediately after the last dose indicating the high cytotoxicity of MRSA4 strain (100% mortality). While the mortalities in other groups injected by the other MRSA extracts ranged from 50 to 75%. In comparison with the normal animal group, all MRSA extracts induced a hepatotoxic effect which was indicated from the significant (p < 0.01) increases in the activities of the serum alanine aminotransferase (ALAT) and aspartate aminotransferase (ASAT) enzymes. Moreover, alkaline phosphatase (ALP) combined with a partial nephrotoxicity that was monitored from the significant elevation of serum urea concentration. While serum creatinine levels did not affect. Similarly, a significant elevation was recorded in serum levels of tumor biomarkers (alpha fetoprotein; AFP, carcinoembryonic antigen; CEA, and lactate dehydrogenase; LDH) reflecting their carcinogenic potential. On the other hand, the percentage of micronuclei (MN) in polychromatic erythrocytes from bone marrow cells was statistically significant in all groups as compared to the control group. The percentage of sperm abnormalities was statistically significant compared to the control. Different types of head abnormalities and coiled tail were recorded. Consequently, the current study focused on fighting MRSA virulence factors by the new compound ayamycin, which proved to be potent anti-virulence factor against all MRSA strains under study by significant decreasing of their streptokinase activities, hemolysin synthesis, biofilm formation, and their cell surface hydrophobicity.

Osteopontin Regulates VEGFA and ICAM-1 mRNA Expression in Breast Carcinoma

OBJECTIVES

To analyze the regulatory role of osteopontin on biomarkers associated with cell survival, invasiveness, and angiogenesis mechanisms in a clinical series and breast cancer cell lines.

METHODS

We analyzed by quantitative real-time polymerase chain reaction the messenger RNA (mRNA) expression of osteopontin, Bcl2, intercellular adhesion molecule 1 (ICAM-1), and vascular endothelial growth factor A (VEGFA) in several breast cancer cell lines and in 148 breast carcinomas classified into intrinsic subtypes.

RESULTS

We found coexpression of osteopontin, Bcl2, ICAM-1, and VEGFA in triple-negative MDA-MB-468 and MDA-MB-231 cell lines. Furthermore, osteopontin silencing by small interfering RNA inhibited ICAM-1 and VEGFA expression and cell proliferation in MDA-MB-468 cells. In breast cancer specimens, we found a positive correlation between osteopontin, ICAM-1, and VEGFA mRNA expression, especially in triple-negative/basal-like tumors. Among patients with osteopontin-overexpressing tumors, VEGFA remained an independent prognostic indicator for recurrence (hazard ratio, 2.95; 95% confidence interval [CI], 1.48-5.87; P = .002) and death (hazard ratio, 3.25; 95% CI, 1.48-7.11; P = .003) (multivariate analysis, Cox regression).

CONCLUSIONS

Our results support that osteopontin regulates ICAM-1 and VEGFA expression mainly in triple-negative/basal-like breast carcinomas, suggesting a relevant role in the pathogenesis and tumor progression of this molecular subtype. Moreover, VEGFA mRNA levels showed an independent prognostic value in patients with breast cancer.

Antibody response to the extracellular adherence protein (Eap) of Staphylococcus aureus in healthy and infected individuals

The extracellular adherence protein (Eap) from Staphylococcus aureus has been suggested as a vaccine candidate and for therapeutic use due to its immunomodulating and antiangiogenic properties; however, little is known about anti-Eap antibodies in humans. We determined anti-Eap antibody titers by enzyme-linked immunosorbent assay and Western blot and measured serum samples from 92 patients with proven S. aureus infections and 93 healthy controls. The functionality of antibodies was assessed by a phagocytosis assay using Eap-coated fluorescent microspheres. Antibodies were detected in all human samples, but not in mice. Patients showed significantly higher titers than controls [immunoglobulin M (IgM), P=0.007; IgG, P<0.0001]. Patients with deep or severe infections showed higher titers than those with superficial or mild disease. Eap alone was sufficient to promote phagocytosis by peripheral blood mononuclear cell and granulocytes that was moderately enhanced in the presence of human serum, but no correlation was found with the levels of anti-Eap antibodies. Anti-Eap antibodies are prevalent in all tested humans and correlate with the severity of S. aureus infection; however, they do not seem to provide protection against invasive infections. Before considering Eap for therapy or as a vaccine candidate, further studies are warranted to assess the impact of the interference between Eap and its specific antibodies.

Osteopontin: an effector and an effect of tumor metastasis

Osteopontin (OPN) is a matricellular protein that is produced by multiple tissues in our body and is most abundant in bone. It is also produced by cancer cells and plays a determinative role in the growth, progression and metastasis of cancer. Clinically, OPN has been reported to be upregulated in tumor cells per se; this is also reflected by increased levels of OPN in the circulation. Thus, increased OPN levels the plasma are an effect of tumor growth and progression. Functionally, high OPN levels are determinative of higher incidence of bone metastases in mouse models and are clinically correlated with metastatic bone disease and bone resorption in advanced breast cancer patients. Several research efforts have been made to therapeutically target and inhibit the activities of OPN. In this article we have reviewed OPN in its role as an effector of critical steps in tumor progression and metastasis, with a particular emphasis on its role in facilitating bone metastasis of breast cancer. We have also addressed the role of the host-derived OPN in influencing the malignant behavior of the tumor cells.

More than one tandem repeat domain of the extracellular adherence protein of Staphylococcus aureus is required for aggregation, adherence, and host cell invasion but not for leukocyte activation

The extracellular adherence protein (Eap) is a multifunctional Staphylococcus aureus protein and broad-spectrum adhesin for several host matrix and plasma proteins. We investigated the interactions of full-length Eap and five recombinant tandem repeat domains with host proteins by use of surface plasmon resonance (BIAcore) and ligand overlay assays. In addition, agglutination and host cell interaction, namely, adherence, invasion, and stimulation of proliferation, were determined. With plasmon resonance, the interaction of full-length Eap isoforms (from strains Newman and Wood 46) with fibrinogen, fibronectin, vitronectin, and thrombospondin-1 was found to be specific but with different affinities for the ligands tested. In the ligand overlay assay, the interactions of five single tandem repeat domains (D1 to D5) of Eap-7 (from strain CI-7) with fibronectin, fibrinogen, vitronectin, thrombospondin-1, and collagen I differed substantially. Most prominently, D3 bound most strongly to fibronectin and fibrinogen. Full-length Eap, but none of the single tandem repeat domains, agglutinated S. aureus and enhanced adherence to and invasion of host cells by S. aureus. Constructs D3-4 and D1-3 (in cis) increased adherence and invasiveness compared to what was seen for single Eap tandem repeat domains. By contrast, single Eap tandem repeat domains and full-length Eap similarly modulated the proliferation of peripheral blood mononuclear cells (PBMCs): low concentrations stimulated, whereas high concentrations inhibited, proliferation. Taken together, the data indicate that Eap tandem repeat domains appear to have distinct characteristics for the binding of soluble ligands, despite a high degree of sequence similarity. In addition, more than one Eap tandem repeat domain is required for S. aureus agglutination, adherence, and cellular invasion but not for the stimulation of PBMC proliferation.