Calcium-sensing stromal interaction molecule 2 upregulates nuclear factor of activated T cells 1 and transforming growth factor-ß signaling to promote breast cancer metastasis.

BACKGROUND: Stromal interaction molecule (STIM) 2 is a key calcium-sensing molecule that regulates the stabilization of calcium ions (Ca2+) and therefore regulates downstream Ca2+-associated signaling and cellular events. We hypothesized that STIM2 regulates epithelial-mesenchymal transition (EMT) to promote breast cancer metastasis. METHODS: We determined the effects of gain, loss, and rescue of STIM2 on cellular motility, levels of EMT-related proteins, and secretion of transforming growth factor-ß (TGF-ß). We also conducted bioinformatics analyses and in vivo assessments of breast cancer growth and metastasis using xenograft models. RESULTS: We found a significant association between STIM2 overexpression and metastatic breast cancer. STIM2 overexpression activated the nuclear factor of activated T cells 1 (NFAT1) and TGF-ß signaling. Knockdown of STIM2 inhibited the motility of breast cancer cells by inhibiting EMT via specific suppression of NFAT1 and inhibited mammary tumor metastasis in mice. In contrast, STIM2 overexpression promoted metastasis. These findings were validated in human tissue arrays of 340 breast cancer samples for STIM2. CONCLUSION: Taken together, our results demonstrated that STIM2 specifically regulates NFAT1, which in turn regulates the expression and secretion of TGF-ß1 to promote EMT in vitro and in vivo, leading to metastasis of breast cancer.

Exosomes derived from breast cancer lung metastasis subpopulations promote tumor self-seeding.

Lung metastasis is a primary obstacle in the clinical treatment of metastatic breast cancer. Most patients with lung metastasis eventually die of recurrence. Recurrence may be related to self-seeding, which occurs when circulating tumor cells re-seed into the tumors they originated from (metastasis or carcinoma in situ). Tumor-derived exosomes have been intensively revealed to promote the progression of various cancers. However, whether tumor-derived exosomes play roles in tumor self-seeding has not yet been identified. By establishing a self-seeding nude mouse model, we found that exosomes derived from MDA231-LM2 cells (subpopulations of breast cancer lung metastasis) potentiate the growth of MDA-MB-231 xenografts. More importantly, laser confocal microscopy and flow cytometry results identified that MDA231-LM2-secreted exosomes promote the seeding of MDA231-LM2 cells into MDA-MB-231 xenografts. These findings suggest MDA231-LM2-secreted exosomes as a promising target to treat breast cancer lung metastasis.

Dioscorea composita WRKY12 is involved in the regulation of salt tolerance by directly activating the promoter of AtRCI2A.

Dioscorea composita (D. composita) is an important medicinal plant worldwide with high economic value. However, its large-scale cultivation was limited by soil salinization. Identification of genes and their mechanisms of action in response to salt stress are critically important. In the present study, we isolated a classical WRKY transcription factor from D. composita, namely DcWRKY12, and analyzed its function in salt tolerance. Expression pattern analysis showed DcWRKY12 is mainly expressed in roots and significantly induced by NaCl, polyethylene glycol-6000 (PEG-6000), and abscisic acid (ABA). Phenotypic and physiological analyses revealed that heterologous expression of DcWRKY12 enhanced salt and osmotic stress tolerance by increasing antioxidant enzyme activity, osmoregulatory substance content, maintaining relative water content and ion homeostasis, decreasing reactive oxygen species and malondialdehyde content. Correspondingly, the overexpression of DcWRKY12 modulated the expression of salt stress-responsive and ion transport-related genes. Dual luciferase assay and Y1H were further confirmed that DcWRKY12 activates the promoter of AtRCI2A through directly binding to the specific W-box cis-acting elements. These results suggest that DcWRKY12 is a positive regulator of salt tolerance in D. composita and has potential applications in salt stress.

MCU-dependent negative sorting of miR-4488 to extracellular vesicles enhances angiogenesis and promotes breast cancer metastatic colonization.

Based on Stephen Paget's well-established theory, both cell-autonomous and non-cell-autonomous mechanisms are crucial for metastasis. Although the mitochondrial calcium uniporter (MCU) has been suggested to be involved in breast cancer (BC) progression via cell-autonomous mechanisms, whether it assists the metastasis of BC cells through non-cell-autonomous mechanisms remains unclear. This study aimed to demonstrate that the MCU regulates BC metastatic colonization via non-cell-autonomous mechanisms. The results suggested that extracellular vesicles (EVs) derived from MCU-downregulated MDA-MB-231 cells suppressed angiogenesis in the metastatic niche in a nude mouse model, thereby hindering the colonization of BC cells. Mechanistically, we revealed that the MCU negatively correlated with miR-4488 in EVs derived from BC cells. Significantly, miR-4488 was determined to suppress angiogenesis of vascular endothelial cells by directly targeting angiogenic CX3CL1. Furthermore, we identified miR-4488 as being significantly downregulated in serum EVs from patients with triple-negative BC. Hence, this study suggests that MCU-dependent negative sorting of miR-4488 to EVs enhances angiogenesis in the metastatic niche and, thus, favors the metastatic colonization of BC cells.

Knockdown of FAM64A suppresses proliferation and migration of breast cancer cells.

BACKGROUND: FAM64A is a mitotic regulator promoting cell metaphase-anaphase transition, and it is frequently reported to be highly expressed in cancer cells. However, the role of FAM64A in human breast cancer (BrC) is poorly studied. METHODS: The expression of FAM64A mRNA in BrC samples was determined by RT-qPCR assay and TCGA database mining. Kaplan-Meier plotter was used to analyze whether FAM64A expression impacted prognosis. Then, the expression of FAM64A was silenced using RNA interference. Cell-counting assay, colony formation assay and flow cytometry assay were conducted to detect proliferation; transwell migration assay, EMT-related proteins expression (E-cadherin, N-cadherin and vimentin), and EMT-related transcription factors mRNA expression (Snail, Twist, Slug) were conducted to evaluate the migration ability. RESULTS: FAM64A was highly expressed in human BrC samples, which was negatively associated with poor survival time. Analysis of FAM64A expression in BrC cell lines demonstrated that the expression of FAM64A was significantly correlated with the proliferation rate and migration ability of BrC cells. Indeed, knockdown of FAM64A suppressed the proliferation of MDA-MB-231 and MCF-7 cells. Importantly, we also found that silencing of FAM64A inhibited the migration of BrC cells via impeding epithelial-mesenchymal transition. CONCLUSIONS: Our findings suggest that FAM64A plays an important role in the proliferation and migration of BrC cells, which might serve as a potential target for BrC treatment.