FAM96A and FAM96B function as new tumor suppressor genes in breast cancer through regulation of the Wnt/ß-catenin signaling pathway.

AIMS: Family with sequence similarity 96 member A and B (FAM96A and FAM96B) are two highly conserved homologous proteins belonging to MIP18 family. Some studies have shown that FAM96A and FAM96B are significantly down-regulated in human gastrointestinal stromal tumors, colon cancer, and liver cancer. However, the molecular mechanisms of FAM96A/B in breast cancer are unknown. This work aims to explore the roles of FAM96A/B in breast cancer progression. MAIN METHODS: Specific siRNAs were used to down-regulate FAM96A/B expression, and recombinant plasmids were used to up-regulate FAM96A/B expression in breast cancer cells. Cell proliferation was measured using MTT and colony formation. Cell cycle and apoptosis were detected by flow cytometry. Cell migration and invasion were examined by wound healing and transwell assays. The relationships among FAM96A/B, EMT and Wnt/ß-catenin pathway were determined by analyzing expression changes of classical markers. KEY FINDINGS: We found that FAM96A/B expression was down-regulated in breast cancer. FAM96A/B overexpression suppressed breast cancer cell proliferation, invasion and migration, induced cell apoptosis and caused cell cycle arrest. Conversely, FAM96A/B knockdown exhibited the opposite effects. Moreover, our data demonstrated that FAM96A/B overexpression suppressed EMT and Wnt/ß-catenin pathway, while FAM96A/B knockdown showed the promoting effects on EMT and Wnt/ß-catenin pathway. Furthermore, a Wnt pathway inhibitor, XAV-939 reversed the promoting effects of FAM96A/B knockdown on breast cancer progression. SIGNIFICANCE: Our findings suggest that FAM96A/B may function as new tumor suppressor genes and inhibit breast cancer progression via modulating Wnt/ß-catenin pathway, which can provide the potential markers for breast cancer diagnosis and therapy.

Roles of cell fusion between mesenchymal stromal/stem cells and malignant cells in tumor growth and metastasis.

Invasion and metastasis are the basic characteristics and important markers of malignant tumors, which are also the main cause of death in cancer patients. Epithelial-mesenchymal transition (EMT) is recognized as the first step of tumor invasion and metastasis. Many studies have demonstrated that cell fusion is a common phenomenon and plays a critical role in cancer development and progression. At present, cancer stem cell fusion has been considered as a new mechanism of cancer metastasis. Mesenchymal stromal/stem cell (MSC) is a kind of adult stem cells with high self-renewal ability and multidifferentiation potential, which is used as a very promising fusogenic candidate in the tumor microenvironment and has a crucial role in cancer progression. Many research results have shown that MSCs are involved in the regulation of tumor growth and metastasis through cell fusion. However, the role of cell fusion between MSCs and malignant cells in tumor growth and metastasis is still controversial. Several studies have demonstrated that MSCs can enhance malignant characteristics, promoting tumor growth and metastasis by fusing with malignant cells, while other conflicting reports believe that MSCs can reduce tumorigenicity upon fusion with malignant cells. In this review, we summarize the recent research on cell fusion events between MSCs and malignant cells in tumor growth and metastasis. The elucidation of the molecular mechanisms between MSC fusion and tumor metastasis may provide an effective strategy for tumor biotherapy.

Effects of treadmill exercise on the regulation of tight junction proteins in aged mice.

Tight junction protein is representative regulator of gut permeability. Also, it has been noted for controlling inflammatory responses through tight junction. Therefore, in this study, we examined that whether tight junction protein is changed in aged mice, and to further, confirmed the effect of treadmill exercise on the tight junction protein. In in vitro study, doxorubicin that induces cell senescence was treated to Caco2 cells (colon cell) to mimic aging effect. After that, 5-aminoimidazole-4-carboxamide-1-ß-D-ribofuranoside (AICAR), exercise mimic chemical that stimulates AMPK level, was also administered to Caco2 cells. In animal study, 2 months and 21 months C57BL/6 J mouse were treated with treadmill exercise for 4 weeks (YE = 5, OE = 5). Then, the tight junction protein expression level was examined by western blot. Also, serum lipopolysaccharide (LPS) and zonulin level were analyzed to identify gut permeability. In vitro studies showed that doxorubicin downregulates tight junction protein expression levels in Caco2 cell, and also AICAR treatment upregulates tight junction protein expression levels. In animal study, 4 weeks treadmill exercise upregulated claudin-1 (p < 0.05) and occludin (p < 0.01) protein expression level in 21 months old mice. Also, zonula occluden-1 (ZO-1) protein expression level was not significant difference among all mice group. In addition, old mice group had higher level of serum LPS compared to young mice group, but the level was downregulated in both 2 months and 21 months mice group after four weeks of treadmill exercise. Zonulin, which is known as degrading tight junction protein, is not significantly changed by both age and exercise. This study compared that tight junction protein expression level in old mice compared to its level in young mice, and also clarified that the effect of treadmill exercise on tight junction protein in both young and old mice.

Potential role of exercise-induced glucose-6-phosphate isomerase in skeletal muscle function.

PURPOSE: Recent studies have shown that glucose-6-phosphate isomerase (GPI)-which is a glycolysis interconversion enzyme-reduces oxidative stress. However, these studies are limited to tumors such as fibrosarcoma, and there are no studies that have examined the effects of exercise on GPI expression in mice skeletal muscle. Furthermore, GPI acts in an autocrine manner thorough its receptor, autocrine motility factor receptor (AMFR); therefore, we investigated expression level changes of secreted GPI from skeletal muscle in in vitro study to examine the potential role of GPI on skeletal muscle. METHODS: First, we performed an in vitro study, to identify the condition that upregulates GPI levels in skeletal muscle cells; we treated C2C12 muscle cells with an exercise-mimicking chemical, AICAR. AICAR treatment upregulated GPI expression level in C2C12 cell and its secretomes. To confirm the direct effect of GPI on skeletal muscle cells, we treated C2C12 cells with GPI recombinant protein. RESULTS: We found that GPI improved the viability of C2C12 cells. In the in vivo study, the exercise-treated mice group showed upregulated GPI expression in skeletal muscle. Based on the in vitro study results, we speculated that expression level of GPI in skeletal muscle might be associated with muscle function. We analyzed the association between GPI expression level and the grip strength of the all mice group. The mice group's grip strengths were upregulated after 2 weeks of treadmill exercise, and GPI expression level positively correlated with the grip strength. CONCLUSION: These results suggested that the exercise-induced GPI expression in skeletal muscle might have a positive effect on skeletal muscle function.

A prepared anti-MSTN polyclonal antibody reverses insulin resistance of diet-induced obese rats via regulation of PI3K/Akt/mTOR&FoxO1 signal pathways.

Suppression of myostatin (MSTN) is associated with skeletal muscle atrophy and insulin resistance. However, the mechanisms by which MSTN regulates insulin resistance are not well known. We have explored the signaling pathways through which MSTN regulates insulin resistance in diet-induced obese rats using a polyclonal antibody for MSTN. The anti-MSTN polyclonal antibody significantly improved insulin resistance and whole-body insulin sensitivity, decreased MSTN protein expression in muscle samples by 39% in diet-induced obese rats. Furthermore, the anti-MSTN polyclonal antibody significantly enhanced PI3K activity (140%), Akt phosphorylation (86%), GLUT4 protein expression (23%), the phosphorylation of mTOR (21%), and inhibited the phosphorylation of FoxO1 (57%), but did not affect the phosphorylation of GSK-3ß. Thus, suppression of MSTN by the anti-MSTN polyclonal antibody reverses insulin resistance of diet-induced obesity via MSTN/PI3K/Akt/mTOR and MSTN/PI3K/Akt/FoxO1 signaling pathways.