Cardiotoxicity monitoring guidelines in patients on anti-HER2 therapy

Introduction  Anti-HER2 therapies such as Trastuzumab carry warnings for cardiotoxicity, though cardiac assessment and monitoring remains an area of clinical debate. Utility of cardiotoxicity monitoring protocols in light of refined treatment regimens is unknown. The degree to which day-to-day clinical practice is informed by current guidelines is unclear.  Methods  A brief survey was designed to audit guideline awareness relating to cardiotoxicity prevalence and monitoring in breast cancer patients treated with HER2-targeted therapy amongst a representative cohort (n=10) of non-consultant hospital doctors (NCHDs) on the breast cancer surgical service in a large tertiary referral centre.  Results  Some lack of awareness of current guidelines across grades was evident, which likely reflects a disconnect between the theoretical guidelines and their clinical usefulness, as well as the relatively infrequent prevalence of cardiotoxicity. Although understanding of normal parameters was generally good (80% of NCHDs correctly recognising normal baseline LVEF as >55%), appropriate frequency of monitoring (12 weekly) was underestimated by 90% of this cohort (n=10). All respondents also underestimated the recommended frequency of monitoring in patients with cardiac impairment. Prevalence of cardiotoxicity was overestimated by all respondents. Although 90% of clinicians surveyed could suggest several assessment modalities, MUGA scans were not mentioned, despite being the method suggested in the Irish guidelines.  Conclusion  Cardiotoxicity is an infrequent but clinically important adverse event in the treatment of HER2-positive breast cancer patients. This small study suggests the timeliness of reviewing and potentially updating current guidelines to reflect imaging advances, as well as re-examining the criteria for scanning frequency in light of refined treatment protocols.</p

Cleaved JAM-A - connecting cancer and vascular disease?

Breast cancers that overexpress the human epidermal growth factor receptor-2 (HER2) are associated with aggressive disease and poor patient prognosis. Although several highly-effective HER2 targeted therapies have been developed, they are associated with a high incidence of de novo and acquired drug resistance in patients. Therefore there remains an ongoing need to elucidate mechanisms of resistance in order to establish effective treatments in drug-resistant patients. Proteins which operate upstream of, and regulate, HER2 expression are valid pharmacological targets in this setting. In recent years a correlation between the expression of Junctional Adhesion Molecule-A (JAM-A) and HER2 in breast cancers has been reported, in addition to expressional regulation of HER2 by JAM-A. JAM-A is a tight junction protein with important adhesive functions in multiple physiological barriers, but whose overexpression has also been linked with tumor progression in glioblastoma, gastric, lung and nasopharyngeal cancers, as well as an emerging role in cancer stem cell maintenance</p

Dynamic interplay between adhesion surfaces in carcinomas: Cell-cell and cell-matrix crosstalk.

Cell-cell and cell-matrix signaling and communication between adhesion sites involve mechanisms which are required for cellular functions during normal development and homeostasis; however these cellular functions and mechanisms are often deregulated in cancer. Aberrant signaling at cell-cell and cell-matrix adhesion sites often involves downstream mediators including Rho GTPases and tyrosine kinases. This review discusses these molecules as putative mediators of cellular crosstalk between cell-cell and cell-matrix adhesion sites, in addition to their attractiveness as therapeutic targets in cancer. Interestingly, inter-junctional crosstalk mechanisms are frequently typified by the way in which bacterial and viral pathogens opportunistically infect or intoxicate mammalian cells. This review therefore also discusses the concept of learning from pathogen-host interaction studies to better understand coordinated communication between cell-cell and cell-matrix adhesion sites, in addition to highlighting the potential therapeutic usefulness of exploiting pathogens or their products to tap into inter-junctional crosstalk. Taken together, we feel that increased knowledge around mechanisms of cell-cell and cell-matrix adhesion site crosstalk and consequently a greater understanding of their therapeutic targeting offers a unique opportunity to contribute to the emerging molecular revolution in cancer biology.</p

Tight junction protein Junctional Adhesion Molecule-A regulates the expression of receptor tyrosine kinase EPHA2 in triple-negative breast cancer cells

Breast tumors lacking expression of the human epidermal growth factor receptor-2 (HER2), progesterone receptor (PR) and estrogen receptor (ERα) are defined as triple negative breast cancers (TNBC). A lack of targeted therapies has impaired TNBC patient prognosis. It has previously been shown that high expression of Junctional Adhesion Molecule-A (JAM-A) correlates with aggressive breast cancer patient phenotypes, and that JAM-A regulates the expression of HER2 in breast cancer cells. Accordingly, we hypothesized that JAM-A might regulate the expression of other receptor tyrosine kinases. We show for the first time that JAM-A may regulate the expression of the EPHA2 receptor in TNBC cells and propose that this pathway merits deeper investigation for its therapeutic value in TNBC settings. </p

A transcriptional link between HER2, JAM-A and FOXA1 in breast cancer

Overexpression of the human epidermal growth factor receptor-2 (HER2) is associated with aggressive disease in breast and certain other cancers. At a cellular level, the adhesion protein Junctional Adhesion Molecule-A (JAM-A) has been reported to regulate the expression of HER3 via a transcriptional pathway involving FOXA1. Since FOXA1 is also a suggested transcription factor for HER2, this study set out to determine if JAM-A regulates HER2 expression via a similar mechanism. An integrated tripartite approach was taken, involving cellular expression studies after targeted disruption of individual players in the putative pathway, in silico identification of relevant HER2 promoter regions and, finally, interrogation of cancer patient survival databases to deconstruct functionally important links between HER2, JAM-A and FOXA1 gene expression. The outcome of these investigations revealed a unidirectional pathway in which JAM-A expression transcriptionally regulates that of HER2 by influencing the binding of FOXA1 to a specific site in the HER2 gene promoter. Moreover, a correlation between JAM-A and HER2 gene expression was identified in 75% of a sample of 40 cancer types from The Cancer Genome Atlas, and coincident high mean mRNA expression of JAM-A, HER2 and FOXA1 was associated with poorer survival outcomes in HER2-positive (but not HER2-negative) patients with either breast or gastric tumors. These investigations provide the first evidence of a transcriptional pathway linking JAM-A, HER2 and FOXA1 in cancer settings, and support potential future pharmacological targeting of JAM-A as an upstream regulator of HER2

The Contribution of Ig-Superfamily and MARVEL D Tight Junction Proteins to Cancer Pathobiology.

The epithelial linings of eukaryotic organs form dynamically-regulated selectively-permeable barriers that control the movement of substances into (and out of) mucosal tissues. The principal structural determinants of epithelial barrier function are intercellular tight junctions (TJs), multi-protein complexes composed of claudin and non-claudin transmembrane proteins in addition to cytosolic linker proteins. As well as their crucial roles in barrier function, it is now well recognized that TJ proteins coordinate a variety of signaling and trafficking functions regulating physiological events such as cell differentiation, proliferation, migration and polarity. Accordingly, dysregulations in TJ protein expression or function are increasingly being linked to several pathophysiologies including cancer. To date, claudins have received the most attention as putative contributors to cancer initiation or progression. However the contribution of non-claudin transmembrane TJ proteins (including select immunoglobulin superfamily members, nectins, occludin and Marvel D family members) to the pathophysiology of cancer remains incompletely understood. Therefore the focus of this review is to collate recently-published evidence that supports or discounts a role for non-claudin transmembrane TJ proteins in cancer, and to speculate upon the feasibility of these molecules as prognostic biomarkers or therapeutic targets in cancer.</p

Diterpenoid natural compound C4 (Crassin) exerts cytostatic effects on triple-negative breast cancer cells via a pathway involving reactive oxygen species.

PURPOSE: Triple-negative breast cancers (TNBC) lack expression of three common cell surface receptors, i.e., estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor-2 (HER2). Accordingly, TNBCs are associated with fewer treatment options and a relatively poor prognosis. Having screened a National Cancer Institute natural compound library, the purpose of this study was to investigate the bioactivity of compound C4 (Crassin) in TNBC cells. METHODS: Cell viability assays were performed in two TNBC cell lines, MDA-MB-231 and 4T1, following C4 treatment in the presence or absence of the antioxidant N-acetyl-L-cysteine (NAC). Phosphorylation of Akt and ERK was assessed by Western blotting. Apoptosis, necrosis, autophagy, necroptosis, ferroptosis and cytostasis assays were performed to explain viability deficits resulting from C4 exposure. RESULTS: We found that the viability of the TNBC cells tested decreased in a concentration- and time-dependent fashion following C4 treatment. This decrease coincided with an unexpected increase in the expression of the cell survival effectors pAkt and pERK. In addition, we found that both the decreased cell viability and the increased pAkt/pERK levels could be rescued by the antioxidant NAC, suggesting a central role for reactive oxygen species (ROS) in the mechanism of action of C4. Necrosis, apoptosis, necroptosis and ferroptosis could be ruled out as cell death mechanisms. Instead, we found that C4 induced cytostasis downstream of ROS activation. Finally, we observed a synergistic effect between C4 and the chemotherapeutic drug doxorubicin in TNBC cells. CONCLUSIONS: From our in vitro data we conclude that C4 exerts cytostatic effects on triple-negative breast cancer cells via a pathway involving reactive oxygen species. Its potential value in combination with cytotoxic therapies merits deeper investigation in pre-clinical models.</p

Junctional adhesion molecule-A is co-expressed with HER2 in breast tumors and acts as a novel regulator of HER2 protein degradation and signaling.

Junctional adhesion molecule-A (JAM-A) is a membranous cell-cell adhesion protein involved in tight-junction formation in epithelial and endothelial cells. Its overexpression in breast tumors has recently been linked with increased risk of metastasis. We sought to identify if JAM-A overexpression was associated with specific subtypes of breast cancer as defined by the expression of human epidermal growth factor receptor-2 (HER2), estrogen receptor (ER) and progesterone receptor. To this end, JAM-A immunohistochemistry was performed in two breast cancer tissue microarrays. In parallel, cross-talk between JAM-A, HER2 and ER was examined in several breast cell lines, using complementary genetic and pharmacological approaches. High JAM-A expression correlated significantly with HER2 protein expression, ER negativity, lower patient age, high-grade breast cancers, and aggressive luminal B, HER2 and basal subtypes of breast cancer. JAM-A and HER2 were co-expressed at high levels in vitro in SKBR3, UACC-812, UACC-893 and MCF7-HER2 cells. Knockdown or functional antagonism of HER2 did not alter JAM-A expression in any cell line tested. Interestingly, however, JAM-A knockdown decreased HER2 and ER-α expression, resulting in reduced levels of phospho-(active) AKT without an effect on the extracellular signal-related kinase phosphorylation. The downstream effects of JAM-A knockdown on HER2 and phospho-AKT were partially reversed upon treatment with the proteasomal inhibitor MG132. We conclude that JAM-A is co-expressed with HER2 and associates with aggressive breast cancer phenotypes. Furthermore, we speculate that JAM-A may regulate HER2 proteasomal degradation and activity, potentially offering a promise as a therapeutic target in HER2-positive breast cancers.</p

Development of a novel weighted ranking method for immunohistochemical quantification of a heterogeneously expressed protein in gastro-esophageal cancers

High expression of Junctional Adhesion Molecule-A (JAM-A) has been linked with poor prognosis in several cancers, including breast cancers overexpressing the human epidermal growth factor receptor-2 (HER2). Furthermore, JAM-A expression has been linked with regulating that of HER2, and associated with the development of resistance to HER2-targeted therapies in breast cancer patients. The purpose of this study was to establish a potential relationship between JAM-A and HER2 in HER2-overexpressing gastro-esophageal (GE) cancers. Interrogation of gene expression datasets revealed that high JAM-A mRNA expression was associated with poorer survival in HER2-positive gastric cancer patients. However, high intra-tumoral heterogeneity of JAM-A protein expression was noted upon immunohistochemical scoring of a GE cancer tissue microarray (TMA), precluding a simple confirmation of any relationship between JAM-A and HER2 at protein level. However, in a test-set of 25 full-face GE cancer tissue sections, a novel weighted ranking system proved effective in capturing JAM-A intra-tumoral heterogeneity and confirming statistically sig-nificant correlations between JAM-A/HER2 expression. Given the growing importance of immuno-histochemistry in stratifying cancer patients for the receipt of new targeted therapies, this may sound a cautionary note against over-relying on cancer TMAs in biomarker discovery studies of heterogeneously expressed proteins. It also highlights a timely need to develop validated mechanisms of capturing intra-tumoral heterogeneity to aid in future biomarker/therapeutic target development for the benefit of cancer patients

C3d elicits neutrophil degranulation and decreases endothelial cell migration, with implications for patients with alpha-1 antitrypsin deficiency

Alpha-1 antitrypsin (AAT) deficiency (AATD) is characterized by increased risk for emphysema, chronic obstructive pulmonary disease (COPD), vasculitis, and wound-healing impairment. Neutrophils play a central role in the pathogenesis of AATD. Dysregulated complement activation in AATD results in increased plasma levels of C3d. The current study investigated the impact of C3d on circulating neutrophils. Blood was collected from AATD (n = 88) or non-AATD COPD patients (n = 10) and healthy controls (HC) (n = 40). Neutrophils were challenged with C3d, and degranulation was assessed by Western blotting, ELISA, or fluorescence resonance energy transfer (FRET) substrate assays. Ex vivo, C3d levels were increased in plasma (p p = 0.038) in AATD compared to HC. C3d binding to CR3 receptors triggered primary (p = 0.01), secondary (p = 0.004), and tertiary (p = 0.018) granule release and increased CXCL8 secretion (p = 0.02). Ex vivo plasma levels of bactericidal-permeability-increasing-protein (p = 0.02), myeloperoxidase (p p p p < 0.0001). In summary, AATD patients had increased C3d in plasma and on neutrophil membranes and, together with neutrophil-released granule enzymes, reduced endothelial cell migration and wound healing, with potential implications for AATD-related vasculitis. </p