Metastasis suppressor 1 acts as a tumor suppressor by inhibiting epithelial-to-mesenchymal transition in triple-negative breast cancer

(-)-Epicatechin Inhibits Metastatic-Associated Proliferation, Migration, and Invasion of Murine Breast Cancer Cells In Vitro

Breast cancer, due to its high incidence and mortality, is a public health problem worldwide. Current chemotherapy uses non-specific cytotoxic drugs, which inhibit tumor growth but cause significant adverse effects. (-)-Epicatechin (EC) is part of a large family of biomolecules called flavonoids. It is widely distributed in the plant kingdom; it can be found in green tea, grapes, and cocoa. Several studies in animals and humans have shown that EC induces beneficial effects in the skeletal muscle and the cardiovascular system, reducing risk factors such as arterial hypertension, endothelial dysfunction, damage to skeletal muscle structure, and mitochondrial malfunction by promoting mitochondrial biogenesis, with no adverse effects reported. Recently, we reported that EC had an antitumor effect in a murine triple-negative mammary gland tumor model, decreasing tumoral size and volume and increasing survival by 44%. This work aimed to characterize the effects of flavanol EC on proliferation, migration, and metastasis markers of triple-negative murine breast (4T1) cancer cells in culture. We found proliferation diminished and Bax/Bcl2 ratio increased. When the migration of culture cells was evaluated, we observed a significant reduction in migration. Also, the relative expression of the genes associated with metastasis, Cdh1, Mtss1, Pten, Bmrs, Fat1, and Smad4, was increased. In conclusion, these results contribute to understanding molecular mechanisms activated by EC that can inhibit metastatic-associated proliferation, migration, and invasion of murine breast cancer cells.

Metastasis suppressor 1 interacts with protein tyrosine phosphatase receptor-δ to regulate adipogenesis

Adipogenesis is a finely controlled process and its dysfunction may contribute to metabolic disorders such as obesity. Metastasis suppressor 1 (MTSS1) is a player in tumorigenesis and metastasis of various types of cancers. To date, it is not known whether and how MTSS1 plays a role in adipocyte differentiation. In the current study, we found that MTSS1 was upregulated during adipogenic differentiation of established mesenchymal cell lines and primary cultured bone marrow stromal cells. Gain-of-function and loss-of-function experiments uncovered that MTSS1 facilitated adipocyte differentiation from mesenchymal progenitor cells. Mechanistic explorations revealed that MTSS1 bound and interacted with FYN, a member of Src family of tyrosine kinases (SFKs), and protein tyrosine phosphatase receptor-δ (PTPRD). We demonstrated that PTPRD was capable of inducing the differentiation of adipocytes. Overexpression of PTPRD attenuated the impaired adipogenesis induced by the siRNA targeting MTSS1. Both MTSS1 and PTPRD activated SFKs by suppressing the phosphorylation of SFKs at Tyr530 and inducing the phosphorylation of FYN at Tyr419. Further investigation showed that MTSS1 and PTPRD were able to activate FYN. Collectively, our study has for the first time unraveled that MTSS1 plays a role in adipocyte differentiation in vitro through interacting with PTPRD and thereby activating SFKs such as FYN tyrosine kinase.

Algorithmic reconstruction of glioblastoma network complexity

Glioblastoma is a complex disease that is difficult to treat. Network and data science offer alternative approaches to classical bioinformatics pipelines to study gene expression patterns from single-cell datasets, helping to distinguish genes associated with the control of differentiation and aggression. To identify the key molecular regulators of the networks driving glioblastoma/GSC and predict their cell fate dynamics, we applied a host of data theoretic techniques to gene expression patterns from pediatric and adult glioblastoma, and adult glioma-derived stem cells (GSCs). We identified eight transcription factors (OLIG1/2, TAZ, GATA2, FOXG1, SOX6, SATB2, and YY1) and four signaling genes (ATL3, MTSS1, EMP1, and TPT1) as coordinators of cell state transitions and, thus, clinically targetable putative factors differentiating pediatric and adult glioblastomas from adult GSCs. Our study provides strong evidence of complex systems approaches for inferring complex dynamics from reverse-engineering gene networks, bolstering the search for new clinically relevant targets in glioblastoma.

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Complex cell fate attractors capture glioblastoma differentiation dynamics

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Graph theoretic approaches decode master regulators of GBM glioblastoma cell fate decisions

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Network dynamics of pediatric glioblastoma resemble adult GSCs

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Transcriptional networks may help reprogram glioblastoma behavioral patterns

Metastasis suppressor 1 controls osteoblast differentiation and bone homeostasis through regulating Src-Wnt/β-catenin signaling

Metastasis suppressor 1 (MTSS1) plays an inhibitory role in tumorigenesis and metastasis of a variety of cancers. To date, the function of MTSS1 in the differentiation of marrow stromal progenitor cells remains to be explored. In the current study, we investigated whether and how MTSS1 has a role in osteoblast differentiation and bone homeostasis. Our data showed that MTSS1 mRNA was upregulated during osteoblast differentiation and downregulated in the osteoblastic lineage cells of ovariectomized and aged mice. Functional studies revealed that MTSS1 promoted the osteogenic differentiation from marrow stromal progenitor cells. Mechanistic explorations uncovered that the inactivation of Src and afterward activation of canonical Wnt signaling were involved in osteoblast differentiation induced by MTSS1. The enhanced osteogenic differentiation induced by MTSS1 overexpression was attenuated when Src was simultaneously overexpressed, and conversely, the inhibition of osteogenic differentiation by MTSS1 siRNA was rescued when the Src inhibitor was supplemented to the culture. Finally, the in vivo transfection of MTSS1 siRNA to the marrow of mice significantly reduced the trabecular bone mass, along with the reduction of trabecular osteoblasts, the accumulation of marrow adipocytes, and the increase of phospho-Src-positive cells on the trabeculae. No change in the number of osteoclasts was observed. This study has unraveled that MTSS1 contributes to osteoblast differentiation and bone homeostasis through regulating Src-Wnt/β-catenin signaling. It also suggests the potential of MTSS1 as a new target for the treatment of osteoporosis.

GSDMB is increased in IBD and regulates epithelial restitution/repair independent of pyroptosis

Gasdermins are a family of structurally related proteins originally described for their role in pyroptosis. Gasdermin B (GSDMB) is currently the least studied, and while its association with genetic susceptibility to chronic mucosal inflammatory disorders is well established, little is known about its functional relevance during active disease states. Herein, we report increased GSDMB in inflammatory bowel disease, with single-cell analysis identifying epithelial specificity to inflamed colonocytes/crypt top colonocytes. Surprisingly, mechanistic experiments and transcriptome profiling reveal lack of inherent GSDMB-dependent pyroptosis in activated epithelial cells and organoids but instead point to increased proliferation and migration during in vitro wound closure, which arrests in GSDMB-deficient cells that display hyper-adhesiveness and enhanced formation of vinculin-based focal adhesions dependent on PDGF-A-mediated FAK phosphorylation. Importantly, carriage of disease-associated GSDMB SNPs confers functional defects, disrupting epithelial restitution/repair, which, altogether, establishes GSDMB as a critical factor for restoration of epithelial barrier function and the resolution of inflammation.

Metastasis suppressor 1 interacts with α-actinin 4 to affect its localization and regulate formation of membrane ruffling

Membrane ruffling plays an important role in the directed cell migration and escape of tumor cells from the monolayer. Metastasis suppressor 1 (MTSS1), also known as missing in metastasis, has been implicated in cell morphology, motility, metastasis, and development. Here, the dynamic interaction proteins associated with MTSS1 and involved in membrane ruffling were determined by cross-linking and mass spectrometry analysis. We identified α-actinin 4 (ACTN4) as an interacting protein and confirmed a direct interaction between MTSS1 and ACTN4. Moreover, co-expression of MTSS1 in fibroblasts recruited cytoplasmic ACTN4 to the cell periphery, at which point ruffling became thick and rigid. In MCF-7 cells, MTSS1 knockdown did not show an obvious effect on the cell shape or the distribution of endogenous ACTN4; however, ACTN4 overexpression transformed cell morphology from an epidermal- to a fibroblast-like shape, and further MTSS1 depletion significantly increased the ratio of fibroblast cells exhibiting prominent ruffling. Furthermore, biochemical data suggested that MTSS1 cross-linking with ACTN4 induced the formation of actin fiber bundles into more organized structures in vitro. These data indicated that MTSS1 might recruit cytoplasmic ACTN4 to the cell periphery and regulate cytoskeleton dynamics to restrict its performance in membrane ruffling.

Epigenetics of Triple-negative breast cancer via natural compounds

Triple-negative breast cancer (TNBC) is a highly resistant, lethal, and metastatic sub-division of breast carcinoma, characterized by the deficiency of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). In women, TNBC shows a higher aggressive behavior with poor patient prognosis and a higher recurrence rate during reproductive age. TNBC is defined by the presence of epithelial-to-mesenchymal-transition (EMT), which shows a significant role in cancer progression. At the epigenetic level, TNBC is characterized by epigenetic signatures, such as DNA methylation, histone remodeling, and a host of miRNA, MiR-193, LncRNA, HIF-2α, eEF2K, LIN9/NEK2, IMP3, LISCH7/TGF-β1, GD3s and KLK12 mediated regulation. These modifications either are silenced or activate the necessary genes that are prevalent in TNBC. The review is based on epigenetic mediated mechanistic changes in TNBC. Furthermore, Thymoquinone (TQ), Regorafenib, Fangjihuangqi decoction, Saikosaponin A, and Huaier, etc., are potent antitumor natural compounds extensively reported in the literature. Further, the review emphasizes the role of these natural compounds in TNBC and their possible epigenetic targets, which can be utilized as a potential therapeutic strategy in treatment of TNBC.