Search

[Display omitted] • Trop2 played a vital role in metastasis by Trop2/β-catenin positive feedback loop. • Bruceine D inhibited cancer cells proliferation and metastasis by targeting Trop2. • Bruceine D suppressed Trop2-driven ECM-remodeling and EMT to reduce lung metastatic colonization in vivo. • Bruceine D blocked Trop2/β-catenin complex, inducing β-catenin degradation though ubiquitin. Tumor-associated calcium signal transducer 2 (Trop2) has been used as a transport gate for cytotoxic agents into cells in antibody–drug conjugate designs because of its expression in a wide range of solid tumors. However, the specific role of Trop2 itself in breast cancer progression remains unclear and small molecules targeting Trop2 have not yet been reported. To screen small molecules targeting Trop2, and to reveal its pharmacological effects and the molecular mechanisms of action. Small molecule targeting Trop2 was identified by cell membrane chromatography, and validated by cellular thermal shift assay and point mutation analyses. We investigated the pharmacological effects of Trop2 inhibitor using RNA-seq, human foreskin fibroblast (HFF)-derived extracellular matrix (ECM), Matrigel drop invasion assays, colony-forming assay, xenograft tumor model, 4T1 orthotopic metastasis model and 4T1 experimental metastasis model. The molecular mechanism was determined using immunoprecipitation, mass spectrometry, immunofluorescence, immunohistochemistry and Western blotting. Here we identified Bruceine D (BD) as the inhibitor of Trop2, and demonstrated anti-metastasis effects of BD in breast cancer. Notably, Lys307 and Glu310 residues of Trop2 acted as critical sites for BD binding. Mechanistically, BD suppressed Trop2-induced cancer metastasis by blocking the formation of Trop2/β-catenin positive loop, in which the Trop2/β-catenin complex prevented β-catenin from being degraded via the ubiquitin-proteosome pathway. Destabilized β-catenin caused by BD reduced nucleus translocation, leading to the reduction of transcription of Trop2, the reversal of epithelial-mesenchymal transition (EMT) process, and the inhibition of ECM remodeling, further inhibiting cancer metastasis. Additionally, the inhibitory effects of BD on lung metastatic colonization and the beneficial effects of BD on prolongation of survival were validated in 4T1 experimental metastasis model. These results support the tumor-promoting role of Trop2 in breast cancer by stabilizing β-catenin in Trop2/β-catenin positive loop, and suggest Bruceine D as a promising candidate for Trop2 inhibition. [ABSTRACT FROM AUTHOR]

Breast cancer is one leading cause of death in females, especially triple‐negative breast cancer (TNBC). Hypoxia is a key feature leading to tumour progression driven by hypoxia‐inducible factor (HIF)‐1α. The aim is to investigate the mechanism of HIF‐1α and signal transducer and activator of transcription‐3 (STAT3) interaction and discover a compound to disrupt the interaction in breast cancer cells. The regulation pattern of HIF‐1α and STAT3 was analysed in hypoxic TNBC cells and patient samples. The effects of a natural alkaloid, sanguinarine, on HIF‐1α and STAT3 colocalization and interaction were evaluated in vitro and mouse xenograft models. We observed strong colocalization of HIF‐1α, p‐STAT3‐Tyr and p‐STAT3‐Ser in TNBC patient samples. Sanguinarine could inhibit the nuclear colocalization and interaction of HIF‐1α with p‐STAT3‐Tyr and p‐STAT3‐Ser in vivo and in vitro. Our results may bring insights to the HIF‐1α/STAT3 interaction in breast cancers and suggest sanguinarine as a promising candidate for HIF‐α/STAT3 inhibition. [ABSTRACT FROM AUTHOR]

Aim of the study. To examine the antiproliferation and anti-invasion of Eupolyphaga sinensis Walker 70% ethanol extract (ESWE) on breast cancer and elucidate the underlying signaling mechanisms. Methods. MTT and colony formation assays were used to investigate the effect of ESWE on proliferation of breast cancer cells in vitro. The xenograft mouse tumor model was used to determine the effect of ESWE on breast cancer in vivo. To investigate the underlying molecular mechanisms, we used western blotting to analyze the expression of ERK1/2, CXCR4, matrix metalloproteinase 2 (MMP2), and MMP9 pretreated with ESWE. The stromal cell–derived factor (SDF)-1α-induced migration and invasion potential of breast cancer cells were examined by wound-healing assays and Matrigel invasion chamber assays. Results. ESWE effectively inhibited the proliferation of MDA-MB-435s and MDA-MB-231 cells and exhibited antitumor effects in an MDA-MB-231 xenograft mice model. Furthermore, ESWE suppressed the activity of ERK1/2, a key molecule of MAPK signaling. We also observed that ESWE treatment led to downregulation of CXCR4 expression as well as greatly reduced MMP2 and MMP9. ESWE affected CXCR4 expression partially through the modulation of autocrine vascular endothelial growth factor. However, suppression of CXCR4 expression was the result of downregulation of mRNA expression. Inhibition of CXCR4 expression by ESWE further correlated with the suppression of SDF-1α-induced migration and invasion in breast cancer cells. Conclusion. ESWE exerted its antiproliferation and antiinvasion by regulating MAPK signaling and related metastasis factorsand thus could be a useful therapeutic candidate for breast cancer intervention. [ABSTRACT FROM AUTHOR]

The increased migration and invasion of breast carcinoma cells are key events in the development of metastasis to the lymph nodes and distant organs. CXCR4, the receptor for stromal-derived factor-1, is reportedly involved in breast carcinogenesis and invasion. In this study, we investigated a novel biphenyl urea derivate, TPD7 for its ability to affect CXCR4 expression as well as function in breast cancer cells. We demonstrated that TPD7 inhibited the breast cancer proliferation and down-regulated the CXCR4 expression on breast cancer cells both over-expressing and low-expressing HER2, an oncogene known to induce the chemokine receptor. Treatments with pharmacological proteasome inhibitors partial suppressed TPD7-induced decrease in CXCR4 expression. Real-time PCR analysis revealed that down-regulation of CXCR4 by TPD7 also occurred at the translational level. Inhibition of CXCR4 expression by TPD7 further correlated with the suppression of SDF-1α-induced migration and invasion in breast tumour cells, knockdown of CXCR4 attenuated TPD7-inhibitory effects. In addition, TPD7 treatment significantly suppressed matrix metalloproteinase ( MMP)-2 and MMP-9 expression, the downstream targets of CXCR4, perhaps via inactivation of the ERK signaling pathway. Overall, our results showed that TPD7 exerted its anti-invasive effect through the down-regulation of CXCR4 expression and thus had the potential for the treatment of breast cancer. [ABSTRACT FROM AUTHOR]