Exosomal Wnt7a from a low metastatic subclone promotes lung metastasis of a highly metastatic subclone in the murine 4t1 breast cancer.

BACKGROUND: Patients with triple-negative breast cancer (TNBC) often have poorer prognosis than those with other subtypes because of its aggressive behaviors. Cancer cells are heterogeneous, and only a few highly metastatic subclones metastasize. Although the majority of subclones may not metastasize, they could contribute by releasing factors that increase the capacity of highly metastatic cells and/or provide a favorable tumor microenvironment (TME). Here, we analyzed the interclonal communication in TNBC which leads to efficient cancer progression, particularly lung metastasis, using the polyclonal murine 4T1 BC model. METHODS: We isolated two 4T1 subclones, LM.4T1 and HM.4T1 cells with a low and a high metastatic potential, respectively, and examined the effects of LM.4T1 cells on the behaviors of HM.4T1 cells using the cell scratch assay, sphere-forming assay, sphere invasion assay, RT-qPCR, and western blotting in vitro. We also examined the contribution of LM.4T1 cells to the lung metastasis of HM.4T1 cells and TME in vivo. To identify a critical factor which may be responsible for the effects by LM.4T1 cells, we analyzed the data obtained from the GEO database. RESULTS: Co-injection of LM.4T1 cells significantly augmented lung metastases by HM.4T1 cells. LM.4T1-derived exosomes promoted the migration and invasion of HM.4T1 cells in vitro, and blocking the secretion of exosome abrogated their effects on HM.4T1 cells. Analyses of data obtained from the GEO database suggested that Wnt7a might be a critical factor responsible for the enhancing effects. In fact, a higher level of Wnt7a was detected in LM.4T1 cells, especially in exosomes, than in HM.4T1 cells, and deletion of Wnt7a in LM.4T1 cells significantly decreased the lung metastasis of HM.4T1 cells. Further, treatment with Wnt7a increased the spheroid formation by HM.4T1 cells via activation of the PI3K/Akt/mTOR signaling pathway. Finally, infiltration of αSMA-positive fibroblasts and angiogenesis was more prominent in tumors of LM.4T1 cells and deletion of Wnt7a in LM.4T1 cells markedly reduced angiogenesis. CONCLUSIONS: We demonstrated, for the first time, that a low metastatic subclone can enhance lung metastasis of highly metastatic subclone via exosomal Wnt7a and propose Wnt7a as a molecular target to treat TNBC patients.

Bite force measurement system using pressure-sensitive sheet and silicone impression material.

This study was conducted to reduce the bias in measured values caused by the thickness of materials used in occlusal examinations. To this end, a silicone impression material for bite force measurement and an experimental model of a simplified stomatognathic system were employed in this study. By means of this experimental model, results showed that the effect of bias toward the posterior arch could be reduced in the anterior-posterior distribution of bite forces and in the occlusal contact areas due to the thickness of the materials used in occlusal examinations.

A study on measuring occlusal contact area using silicone impression materials: an application of this method to the bite force measurement system using the pressure-sensitive sheet.

The aim of this study was to establish an objective and quantitative method of measuring occlusal contact areas. To this end, bite records were taken with a silicone impression material and a light transmission device was used to read the silicone impression material. To examine the effectiveness of this novel method, the occlusal contact area of the silicone impression material and its thickness limit of readable range were measured. Results of this study suggested that easy and highly accurate measurements of occlusal contact area could be obtained by selecting an optimal applied voltage of the light transmission device and an appropriate color of the silicone impression material.

Application of direct laminate veneer for enamel protection during orthodontic treatment: an in vivo evaluation.

The aims of this study were to examine the enamel protective effect of a direct laminate veneer against acidic conditions, measure the amount of fluoride released from the veneer and which was taken up by the enamel, as well as evaluate the usefulness of the veneer for orthodontic treatment. First, a veneer was applied to rabbit incisors. Then, apart from using profile measurement microscope and electron probe microanalyzer to measure the roughness and fluoride concentration in the enamel of veneer-covered tooth surface, those of the uncovered adjacent tooth surface were measured too. It was found that the veneer protected the enamel surface from acidic conditions. Furthermore, fluoride ions were taken up by both the uncovered adjacent enamel area as well as by the covered area. These findings suggested that covering the enamel surface with a direct laminate veneer before bracket bonding might be a valuable means of tooth protection and caries prevention.

Indirect laminate veneers as an indirect bonding method.

Indirect bracket bonding methods that use individual tooth transfer trays offer several benefits compared to direct bonding techniques, as well as to indirect bonding systems that use transfer trays that include all of the teeth. Precise and correct bracket position presents the most significant advantage of all indirect bonding procedures, but this new indirect bracket bonding technique also provides unprecedented enamel protection and caries prevention. In addition, it provides accuracy for the recementation of any loose, broken, or lost brackets at their previous sites. This article presents the rationale and a step-by-step guide for implementing this indirect bracket bonding system.