Radiotherapy-Resistant Breast Cancer Cells Enhance Tumor Progression by Enhancing Premetastatic Niche Formation through the HIF-1α-LOX Axis.

Cancer stem cells (CSCs) exist in solid tumors and contribute to therapeutic resistance and disease recurrence. Previously, we reported that radiotherapy-resistant (RT-R)-MDA-MB-231 cells from highly metastatic MDA-MB-231 cells produced more CSCs than any other RT-R-breast cancer cells and showed therapeutic resistance and enhanced invasiveness. Hypoxia inducible factor-1α (HIF-1α) induced in the tumor microenvironment leads to the release of lysyl oxidase (LOX), which mediates collagen crosslinking at distant sites to facilitate environmental changes that allow cancer cells to easily metastasize. Therefore, in this study, we investigated whether RT-R-MDA-MB-231 cells induce greater HIF-1α expression, LOX secretion, and premetastatic niche formation than MDA-MB-231 cells do. RT-R-MDA-MB-231 cells increased HIF-1α expression and LOX secretion compared with MDA-MB-231 cells. Mice harboring RT-R-MDA-MB-231 cell xenografts showed enhanced tumor growth and higher expression of the CSC markers, CD44, Notch-4, and Oct3/4. In addition, mice injected with RT-R-MDA-MB-231 cells exhibited a higher level of HIF-1α in tumor tissue, increased secretion of LOX in plasma, higher induced levels of crosslinked collagen, and a higher population of CD11b+ BMDC recruitment around lung tissue, compared with those injected with MDA-MB-231 cells. These results suggest that RT-R-MDA-MB-231 cells contribute to tumor progression by enhancing premetastatic niche formation through the HIF-1α-LOX axis.

Polyphenols from Artemisia annua L Inhibit Adhesion and EMT of Highly Metastatic Breast Cancer Cells MDA-MB-231.

Recent evidence suggests that polyphenolic compounds from plants have anti-invasion and anti-metastasis capabilities. The Korean annual weed, Artemisia annua L., has been used as a folk medicine for treatment of various diseases. Here, we isolated and characterized polyphenols from Korean A. annua L (pKAL). We investigated anti-metastatic effects of pKAL on the highly metastatic MDA-MB-231 breast cancer cells especially focusing on cancer cell adhesion to the endothelial cell and epithelial-mesenchymal transition (EMT). Firstly, pKAL inhibited cell viability of MDA-MB-231 cells in a dose-dependent manner, but not that of human umbilical vein endothelial cells (ECs). Polyphenols from Korean A. annua L inhibited the adhesion of MDA-MB-231 cells to ECs through reducing vascular cell adhesion molecule-1 expression of MDA-MB-231 and ECs, but not intracellular adhesion molecule-1 at the concentrations where pKAL did not influence the cell viability of either MDA-MB-231 cells nor EC. Further, pKAL inhibited tumor necrosis factor-activated MDA-MB-231 breast cancer cell invasion through inhibition of matrix metalloproteinase-2 and matrix metalloproteinase-9 and EMT. Moreover, pKAL inhibited phosphorylation of Akt, but not that of protein kinase C. These results suggest that pKAL may serve as a therapeutic agent against cancer metastasis at least in part by inhibiting the cancer cell adhesion to ECs through suppression of vascular cell adhesion molecule-1 and invasion through suppression of EMT. Copyright © 2016 John Wiley & Sons, Ltd.

Polyphenol mixtures of Euphorbia supina the inhibit invasion and metastasis of highly metastatic breast cancer MDA-MB-231 cells.

The Korean prostrate spurge Euphorbia supina is abundant in polyphenols and has been used as a folk medicine in Korea against a variety of diseases. Thus, we aimed to investigate the effect of polyphenol mixtures of Korean Euphorbia supina (PES) on the invasion and metastasis of highly metastatic breast cancer MDA-MB-231 cells. Firstly, PES showed no cytotoxicity on cancer cells and endothelial cells (ECs) at the doses of 0.1-10 µg/ml, but showed significant cytotoxicity from 50 µg/ml. Thus, we performed subsequent experiments with PES at doses up to 5 µg/ml. PES dose­dependently suppressed epithelial-mesenchymal transition by downregulating the mesenchymal markers, Snail1 and N-cadherin, showing significant inhibition from 1 and 5 µg/ml, respectively. In addition, PES significantly inhibited MMP-9 activity and LOX release induced by TNF-α at 5 µg/ml. Then, we determined the effect of PES on the expression of adhesion molecules and VE-cadherin phosphorylation. The results showed that PES effectively reduced TNF-α-mediated VCAM-1 expression but not ICAM expression both in the MDA-MB-231 cells and ECs, resulting in the reduced adhesion of MDA-MB-231 to ECs. Finally, PES effectively inhibited MDA-MB-231 cell invasion through ECs, suggesting that PES may serve as a therapeutic agent against cancer metastasis with minimal cytotoxicity to normal cells.

P2Y2R activation by nucleotides released from the highly metastatic breast cancer cell MDA-MB-231 contributes to pre-metastatic niche formation by mediating lysyl oxidase secretion, collagen crosslinking, and monocyte recruitment.

Tumor microenvironmental hypoxia induces hypoxia inducible factor-1α (HIF-1α) overexpression, leading to the release of lysyl oxidase (LOX), which crosslinks collagen at distant sites to facilitate environmental changes that allow cancer cells to easily metastasize. Our previous study showed that activation of the P2Y2 receptor (P2Y2R) by ATP released from MDA-MB-231 cells increased MDA-MB-231 cell invasion through endothelial cells. Therefore, in this study, we investigated the role of P2Y2R in breast cancer cell metastasis to distant sites. ATP or UTP released from hypoxia-treated MDA-MB-231 cells induced HIF-1α expression and LOX secretion by the activation of P2Y2R, and this phenomenon was significantly reduced in P2Y2R-depleted MDA-MB-231 cells. Furthermore, P2Y2R-mediated LOX release induced collagen crosslinking in an in vitro model. Finally, nude mice injected with MDA-MB-231 cells showed high levels of LOX secretion, crosslinked collagen and CD11b+ BMDC recruitment in the lung; however, mice that were injected with P2Y2R-depleted MDA-MB-231 cells did not exhibit these changes. These results demonstrate that P2Y2R plays an important role in activation of the HIF-1α-LOX axis, the induction of collagen crosslinking and the recruitment of CD11b+ BMDCs. Furthermore, P2Y2R activation by nucleotides recruits THP-1 monocytes, resulting in primary tumor progression and pre-metastatic niche formation.

P2Y2 R activation by nucleotides promotes skin wound-healing process.

P2Y2 R has been shown to be upregulated in a variety of tissues in response to stress or injury and to mediate tissue regeneration through its ability to activate multiple signalling pathways. This study aimed to investigate the role of P2Y2 R in the wound-healing process and the mechanisms by which P2Y2 R activation promotes wound healing in fibroblasts. The role of P2Y2 R in skin wound healing was examined using a full-thickness skin wound model in wildtype (WT) and P2Y2 R(-/-) mice and an in vitro scratch wound model in control or P2Y2 R siRNA-transfected fibroblasts. WT mice showed significantly decreased wound size compared with P2Y2 R(-/-) mice at day 14 post-wounding, and immunohistochemical analysis showed that a proliferation marker Ki67 and extracellular matrix (ECM)-related proteins VEGF, collagen I, fibronectin and α-SMA were overexpressed in WT mice, which were reduced in P2Y2 R(-/-) mice. Scratch-wounded fibroblasts increased ATP release, which peaked at 5 min. In addition, scratch wounding increased the level of P2Y2 R mRNA. Activation of P2Y2 R by ATP or UTP enhanced proliferation and migration of fibroblasts in in vitro scratch wound assays and were blocked by P2Y2 R siRNA. Finally, ATP or UTP also increased the levels of ECM-related proteins through the activation of P2Y2 R in fibroblasts. This study suggests that P2Y2 R may be a potential therapeutic target to promote wound healing in chronic wound diseases.

Honokiol inhibits U87MG human glioblastoma cell invasion through endothelial cells by regulating membrane permeability and the epithelial-mesenchymal transition.

Glioblastoma is one of the most lethal and prevalent malignant human brain tumors, with aggressive proliferation and highly invasive properties. There is still no effective cure for patients with glioblastoma. Honokiol, derived from Magnolia officinalis, can cross the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB), making it a strong candidate for an effective drug for the treatment of brain tumors, including glioblastoma. In our previous study, we demonstrated that honokiol effectively induced apoptotic cell death in glioblastoma. Metastasis poses the largest problem to cancer treatment and is the primary cause of death in cancer patients. Thus, in this study, we investigated the effect of honokiol on the cell invasion process of U87MG human glioblastoma cells through brain microvascular endothelial cells (BMECs) and its possible mechanisms. Honokiol dose-dependently inhibited TNF-α-induced VCAM-1 expression in BMECs and adhesion of U87MG to BMECs. Moreover, honokiol effectively blocked U87MG invasion through BMEC-Matrigel-coated transwell membranes. Increased phosphorylation of VE-cadherin and membrane permeability by TNF-α were suppressed by honokiol in BMECs. Furthermore, we investigated the effect of honokiol on the epithelial-mesenchymal transition (EMT) in U87MG cells. Honokiol reduced the expression levels of Snail, N-cadherin and ß-catenin, which are mesenchymal markers, but increased E-cadherin, an epithelial marker. In conclusion, these results suggest that honokiol inhibits metastasis by targeting the interaction between U87MG and BMECs, regulating the adhesion of U87MG to BMECs by inhibiting VCAM-1, and regulating the invasion of U87MG through BMECs by reducing membrane permeability and EMT processes of U87MG cells.