Sentinel lymph node biopsy after neoadjuvant chemotherapy in breast cancer

The indication of neoadjuvant chemotherapy has been recently extended; it is now applied not only in locally advanced breast cancer but in primarily resecable tumours as well, in order to promote breast conservation. Based on recent clinical results, the reconsideration of traditional lymph node dissection in axillary staging is timely in patients receiving neoadjuvant chemotherapy. Precise axillary staging needs surgical removal of lymph nodes. Based on prospective randomised trials, sentinel lymph node biopsy appears to be appropriate for axillary staging even in tumours requiring neoadjuvant treatment. The extended indication of sentinel lymph node biopsy raises several questions and problems. In the present paper the authors review the results and possible limitations of sentinel lymph node biopsy in relation to neoadjuvant chemotherapy.     

Real-time visualization of cytoplasmic calpain activation and calcium deregulation in acute glutamate excitotoxicity

Although calpain (EC 3.4.22) protease activation was suggested to contribute to excitotoxic delayed calcium deregulation (DCD) via proteolysis of Na⁺/Ca²⁺ exchanger 3 (NCX3), cytoplasmic calpain activation in relation to DCD has never been visualized in real-time. We employed a calpain fluorescence resonance energy transfer substrate to simultaneously image calpain activation and calcium deregulation in live cortical neurons. A calpain inhibitor-sensitive decline in fluorescence resonance energy transfer was observed at 39 ± 5 min after the occurrence of DCD in neurons exposed to continuous glutamate (100 μM). Inhibition of calpain by calpeptin did not delay the onset of DCD, recovery from DCD-like reversible calcium elevations, or cell death despite inhibiting α-spectrin processing by > 90%. NCXs reversed during glutamate exposure, the NCX antagonist KB-R7943 prolonged the time to DCD, and significant NCX3 cleavage following 90 min of glutamate exposure was not observed. Our findings suggest that robust calpain activation associated with acute glutamate toxicity occurs only after a sustained loss in calcium homeostasis. Processing of NCX3 or other calpain substrates is unlikely to be the primary cause of acute excitotoxicity in cortical neurons. However, a role for calpain as a contributing factor or in response to milder glutamate insults is not excluded.     

A biased ligand for OXE-R uncouples Gα and Gβγ signaling within a heterotrimer

Differential targeting of heterotrimeric G protein versus β-arrestin signaling are emerging concepts in G protein-coupled receptor (GPCR) research and drug discovery, and biased engagement by GPCR ligands of either β-arrestin or G protein pathways has been disclosed. Herein we report on a new mechanism of ligand bias to titrate the signaling specificity of a cell-surface GPCR. Using a combination of biomolecular and virtual screening, we identified the small-molecule modulator Gue1654, which inhibits Gβγ but not Gα signaling triggered upon activation of Gα(i)-βγ by the chemoattractant receptor OXE-R in both recombinant and human primary cells. Gue1654 does not interfere nonspecifically with signaling directly at or downstream of Gβγ. This hitherto unappreciated mechanism of ligand bias at a GPCR highlights both a new paradigm for functional selectivity and a potentially new strategy to develop pathway-specific therapeutics.     

Laropiprant Attenuates EP3 and TP Prostanoid Receptor-Mediated Thrombus Formation

The use of the lipid lowering agent niacin is hampered by a frequent flush response which is largely mediated by prostaglandin (PG) D(2). Therefore, concomitant administration of the D-type prostanoid (DP) receptor antagonist laropiprant has been proposed to be a useful approach in preventing niacin-induced flush. However, antagonizing PGD(2), which is a potent inhibitor of platelet aggregation, might pose the risk of atherothrombotic events in cardiovascular disease. In fact, we found that in vitro treatment of platelets with laropiprant prevented the inhibitory effects of PGD(2) on platelet function, i.e. platelet aggregation, Ca(2+) flux, P-selectin expression, activation of glycoprotein IIb/IIIa and thrombus formation. In contrast, laropiprant did not prevent the inhibitory effects of acetylsalicylic acid or niacin on thrombus formation. At higher concentrations, laropiprant by itself attenuated platelet activation induced by thromboxane (TP) and E-type prostanoid (EP)-3 receptor stimulation, as demonstrated in assays of platelet aggregation, Ca(2+) flux, P-selectin expression, and activation of glycoprotein IIb/IIIa. Inhibition of platelet function exerted by EP4 or I-type prostanoid (IP) receptors was not affected by laropiprant. These in vitro data suggest that niacin/laropiprant for the treatment of dyslipidemias might have a beneficial profile with respect to platelet function and thrombotic events in vascular disease.     

Second breast-conserving surgery and reirradiation with interstitial high-dose-rate brachytherapy for the management of intra-breast recurrences -- 5-year results

The purpose of our work was to evaluate the efficacy of second breast-conserving surgery (BCS) and reirradiation with interstitial high-dose-rate (HDR) brachytherapy (BT) for the management of local recurrences. Between 1999 and 2010, fifteen patients initially treated for breast carcinoma by BCS and radiation therapy who had isolated intra-breast recurrence underwent second BCS and perioperative HDR multicatheter BT. Breast cancer related events, late side effects, and cosmetic results were assessed. At a median follow-up of 62 months (range: 11-127) second local recurrence has not occurred, yielding a 100% mastectomy-free survival. Four patients (27%) developed subsequent distant metastasis and died of breast cancer. The 5-year actuarial rate of disease-free and overall survival was 69% and 85%, respectively. Cosmetic results were rated excellent, good, fair, poor, and unknown in 1 (7%), 10 (66%), 2 (13%), 1 (7%), and 1 (7%) patients, respectively. Grade 2 fibrosis and skin toxicity occurred in 1 (7%) and 1 (7%) patients. Asymptomatic fat necrosis was detected in 9 (60%) women. No patient developed grade 3-4 late side effects. Second BCS followed by partial breast reirradiation is a safe and effective option for the management of selected patients developing intra-breast recurrence after previous breast-conserving therapy. Perioperative HDR BT may decrease the risk of second local relapse with acceptable cosmetic results and low rate of late side effects.     

Need for developing a new strategy in the follow-up of colorectal cancer patients; the micro RNAs (miRNAs), as potential new biomarkers of early detection

In the mortality statistics of European countries colorectal cancers are known to assume the 2nd place after lung cancer. The mortality indices are particularly unfavourable in Hungary. Early detection is therefore of vital importance to the patient either the detection of the primary or recurrence after successful surgery is concerned. The latter is only feasible within a proper follow-up strategy. The present review focuses on follow-up due after surgical removal of the tumour with special emphasis on the efficacy of a new biomarker group (miRNAs) and their potential combination with the traditional markers. It is a model in the follow-up strategy that considers the results of risk assessment, as well. Since the methodology and strategy of follow-up are still controversial matters it is obvious that the development of a new follow-up strategy is imperative.     

Differential response of arterial and venous endothelial cells to extracellular matrix is modulated by oxygen

Binding of endothelial cell (EC) integrins to extracellular-matrix (ECM) components is one of the key events to trigger intracellular signaling that will ultimately result in proper vascular development. Even within one tissue, the endothelial phenotype differs between arteries and veins. Here, we tested the hypothesis that anchorage-dependent processes, such as proliferation, viability, survival and actin organization of venous (VEC) and arterial EC (AEC) differently depend on ECM proteins. Moreover, because of different oxygen tension in AEC and VEC, we tested oxygen as a co-modulator of ECM effects. Primary human placental VEC and AEC were grown in collagens I and IV, fibronectin, laminin, gelatin and uncoated plates and exposed to 12 and 21% oxygen. Our main findings revealed that VEC are more sensitive than AEC to changes in the ECM composition. Proliferation and survival of VEC, in contrast to AEC, were profoundly increased by the presence of collagen I and fibronectin when compared with gelatin or uncoated plates. These effects were reversed by inhibition of focal adhesion kinase (Fak) and modulated by oxygen. VEC were more susceptible to the oxygen-dependent ECM effects than AEC. However, no differential ECM effect on actin organization was observed between the two cell types. These data provide first evidence that AEC and VEC from the same vascular loop respond differently to ECM and oxygen in a Fak-dependent manner.