Nuclear beta-catenin and CD44 upregulation characterize invasive cell populations in non-aggressive MCF-7 breast cancer cells.

BACKGROUND: In breast cancer cells, the metastatic cell state is strongly correlated to epithelial-to-mesenchymal transition (EMT) and the CD44+/CD24- stem cell phenotype. However, the MCF-7 cell line, which has a luminal epithelial-like phenotype and lacks a CD44+/CD24- subpopulation, has rare cell populations with higher Matrigel invasive ability. Thus, what are the potentially important differences between invasive and non-invasive breast cancer cells, and are the differences related to EMT or CD44/CD24 expression? METHODS: Throughout the sequential selection process using Matrigel, we obtained MCF-7-14 cells of opposite migratory and invasive capabilities from MCF-7 cells. Comparative analysis of epithelial and mesenchymal marker expression was performed between parental MCF-7, selected MCF-7-14, and aggressive mesenchymal MDA-MB-231 cells. Furthermore, using microarray expression profiles of these cells, we selected differentially expressed genes for their invasive potential, and performed pathway and network analysis to identify a set of interesting genes, which were evaluated by RT-PCR, flow cytometry or function-blocking antibody treatment. RESULTS: MCF-7-14 cells had enhanced migratory and invasive ability compared with MCF-7 cells. Although MCF-7-14 cells, similar to MCF-7 cells, expressed E-cadherin but neither vimentin nor fibronectin, beta-catenin was expressed not only on the cell membrane but also in the nucleus. Furthermore, using gene expression profiles of MCF-7, MCF-7-14 and MDA-MB-231 cells, we demonstrated that MCF-7-14 cells have alterations in signaling pathways regulating cell migration and identified a set of genes (PIK3R1, SOCS2, BMP7, CD44 and CD24). Interestingly, MCF-7-14 and its invasive clone CL6 cells displayed increased CD44 expression and downregulated CD24 expression compared with MCF-7 cells. Anti-CD44 antibody treatment significantly decreased cell migration and invasion in both MCF-7-14 and MCF-7-14 CL6 cells as well as MDA-MB-231 cells. CONCLUSIONS: MCF-7-14 cells are a novel model for breast cancer metastasis without requiring constitutive EMT and are categorized as a "metastable phenotype", which can be distinguished from both epithelial and mesenchymal cells. The alterations and characteristics of MCF-7-14 cells, especially nuclear beta-catenin and CD44 upregulation, may characterize invasive cell populations in breast cancer.

Interactions of carotid sinus or aortic input with emetic signals from gastric afferents and vestibular system.

This study investigated how baro- and chemoreceptor afferents interact with emetic signals from gastric afferents and the vestibular system, and how these interactions modulate emetic and prodromal responses. We performed splanchnic denervation and abdominal vagotomy in anesthetized shrews (Suncus murinus), and then induced emetic responses by gastric distension. Next, we investigated the effects of these gastric afferent sections on cardiovascular and emetic responses induced by electrical stimulation of the aortic depressor nerve (ADN) and the carotid sinus nerve (CSN) with or without gastric distension. Splanchnic denervation abolished the prodromal response before retching and aortic baroreflex inhibition caused by gastric distension, but had no effects on the emetic response. In contrast, abdominal vagotomy abolished the emetic response induced by gastric distension with or without CSN stimulation, but without affecting gastric distension-induced or CSN stimulation-induced vascular and respiratory responses. In conscious animals, CSN denervation significantly suppressed veratrine- and motion-induced emetic responses, whereas ADN denervation had no significant effects. These results suggest that aortic baroreflex inhibition via the activation of splanchnic afferents contributes to the prodromal response before retching and circulatory homeostasis. In contrast, carotid sinus inputs, which are usually non-emetic signals, interact with vagal and vestibular inputs, and modulate the development of retching and vomiting.

Modulation of emetic response by carotid baro- and chemoreceptor activations.

We hypothesized that baroreceptor or chemoreceptor activation might be involved in the emetic, and prodromal cardiovascular and respiratory responses. To test this hypothesis, we induced the emetic responses by gastric distension in anesthetized Suncus murinus (house musk shrew), that had intact and absent baroreceptor and chemoreceptor afferents. Secondly, we stimulated the aortic depressor nerve (ADN) and the carotid sinus nerve (CSN) with or without gastric distension. Internal carotid artery ligation in the bifurcation area, which abolished reflex bradycardia by baroreceptor activation, and abolition of chemoreceptor reflex bradycardia and hyperventilation, by carotid body denervation, suppressed the emetic response but did not abolish it. ADN denervation, which produced no significant effects on the baroreceptor or chemoreceptor reflex bradycardia, had no effect on the emetic response, including the prodromal phase. CSN stimulation with gastric distension elicited retching accompanied by reflex bradycardia and hypotension during or just after stimulation, whereas ADN stimulation with gastric distension did not induce the cardiovascular reflex, and had no effects on the emetic response. These results indicate that carotid, rather than aortic, baroreceptor or chemoreceptor activation plays an important role in the augmentation of cardiac parasympathetic activity and the development of emetic response. In conclusion, carotid baroreceptor or chemoreceptor activation, which is non-emetic stimulation, acts as a modulator in the central mechanisms of emesis.

Role of the autonomic nervous system in emetic and cardiovascular responses in Suncus murinus.

To clarify the role of the autonomic nervous system in cardiovascular and emetic responses, we studied the influence of drugs that act on autonomic nervous function on emetic and cardiovascular responses induced by chemical or mechanical stimulation to the stomach in two strains of Suncus murinus, Jic:SUN-Her and Jic:SUN-Ler. Latency to the first retching in Jic:SUN-Her was significantly shorter than that in Jic:SUN-Ler to both mechanical and chemical stimulation. This result indicated that there are different sensitivities to mechanical and chemical stimulation to the stomach in these two strains of suncus. However, the numbers of emetic episodes were almost the same in these two strains. Mean blood pressure significantly increased from baseline prior to retching in both strains. Heart rate decreased in Jic:SUN-Her and increased in Jic:SUN-Ler prior to retching, suggesting that a different baroreflex responsiveness might exist in these two strains of suncus. Administration of acetylcholine and phenylephrine affected emetic response induced by mechanical and chemical stimulation. Although the baseline values of mean blood pressure and heart rate after administration of these drugs were different, changes in mean blood pressure and heart rate prior to retching were unaffected. This result suggested that the state of autonomic activity before the emetic response might be important in the development of the emetic response. Pretreatment with hexamethonium suppressed the cardiovascular response prior to retching and prolonged the latency to the first retching. This result indicated that there was an interaction between the mechanisms involved in cardiovascular and emetic responses. The change in autonomic function during the emetic response, especially enhancement of sympathetic activity prior to retching, may be relevant to emetic and cardiovascular responses. Moreover, these results suggest that different autonomic function or different baroreflex responsiveness in Jic:SUN-Her and Jic:SUN-Ler may be involved in emetic responses.

Diurnal fluctuations of heart rate, body temperature and locomotor activity in the house musk shrew (Suncus murinus).

Diurnal fluctuations of heart rate (HR), body temperature (BT) and locomotor activity (LA) in the unanaesthetized and unrestrained house musk shrew (Suncus murinus) were studied using a telemetry system. Six adult male shrews (Jic:SUN) weighing 60-70 g were used in the present study. They were housed under conditions of 24 C and a 12/12-hr light-dark cycle. HR, BT and LA were recorded over 10 days, following the post-implantation period (10 days or more) of the telemetric transmitter. A clear nocturnal rhythm of LA was shown, while intermittent and short-term LA were shown during the light period. The mean HR was 323.5 +/- 8.8 bpm in the light period and 354.3 +/- 5.2 bpm in the dark period, and the fluctuation of HR showed a nocturnal pattern. A nocturnal pattern was also observed in BT fluctuation, and all animals lowered their body temperature from 35-37 C to approximately 30 C or below, mostly during the light period. The fall of body temperature progressed over 2-3 hr, and then rose to the baseline temperature rapidly within approximately 30 min. While the body temperature fell, HR markedly decreased to approximately 100 bpm. These results suggest that the shrew has unique physiological properties in maintaining metabolic balance which are anticipated to be caused by the dramatic alteration of the autonomic nervous function.