Effects of N-acetyl-l-cysteine on adhesive strength between breast cancer cell and extracellular matrix proteins after ionizing radiation

Aims: To evaluate the effect of N-acetyl-L-cysteine (LNAC), a common ROS scavenger, on the adhesive affinity between MDA-MB-231 breast cancer cells and extracellular matrix (ECM) proteins after IR.     

Pro-metastatic functions of Notch signaling is mediated by CYR61 in breast cells

Metastasis is the main cause of cancer related deaths, and unfolding the molecular mechanisms underlying metastatic progression is critical for the development of novel therapeutic approaches. Notch is one of the key signaling pathways involved in breast tumorigenesis and metastasis. Notch activation induces pro-metastatic processes such as migration, invasion and epithelial to mesenchymal transition (EMT). However, molecular mediators working downstream of Notch in these processes are not fully elucidated. CYR61 is a secreted protein implicated in metastasis, and its inhibition by a monoclonal antibody suppresses metastasis in xenograft breast tumors, indicating the clinical importance of CYR61 targeting. Here, we aimed to investigate whether CYR61 works downstream of Notch in inducing pro-metastatic phenotypes in breast cells. We showed that CYR61 expression is positively regulated by Notch activity in breast cells. Notch1-induced migration, invasion and anchorage independent growth of a normal breast cell line, MCF10A, were abrogated by CYR61 silencing. Furthermore, upregulation of core EMT markers upon Notch1-activation was impaired in the absence of CYR61. However, reduced migration and invasion of highly metastatic cell line, MDA MB 231, cells upon Notch inhibition was not dependent on CYR61 downregulation. In conclusion, we showed that in normal breast cell line MCF10A, CYR61 is a mediator of Notch1-induced pro-metastatic phenotypes partly via induction of EMT. Our results imply CYR61 as a prominent therapeutic candidate for a subpopulation of breast tumors with high Notch activity.     

MiR-489 regulates chemoresistance in breast cancer via epithelial mesenchymal transition pathway

To investigate the role of microRNAs in the development of chemoresistance and related epithelial–mesenchymal transition (EMT), we examined the effect of miR-489 in adriamycin (ADM)-resistant human breast cancer cells (MCF-7/ADM). MiR-489 was significantly suppressed in MCF-7/ADM cells compared with chemosensitive parental control MCF-7/WT cells. Forced-expression of miR-489 reversed chemoresistance. Furthermore, Smad3 was identified as the target of miR-489 and is highly expressed in MCF-7/ADM cells. Forced expression of miR-489 both inhibited Smad3 expression and Smad3 related EMT properties. Finally, the interactions between Smad3, miR-489 and EMT were confirmed in chemoresistant tumor xenografts and clinical samples, indicating their potential implication for treatment of chemoresistance.     

FOXO3a inhibits the EMT and metastasis of breast cancer by regulating TWIST-1 mediated miR-10b/CADM2 axis

BackgroundBreast cancer is the most common malignancy and has been considered as a leading cause of cancer death in women. Exploring the mechanism of breast cancer metastasis is extremely important for seeking novel therapeutic strategies and improving prognosis.MethodsClinical specimens and pathological characteristics were collected for evaluating the expression of forkhead box class O 3a (FOXO3a) and twist-related protein 1 (TWIST-1) in breast cancer tissues. CCK-8 assay was used to analyze cell proliferation. Cell invasion and migration were assessed by transwell assays. The expression of FOXO3a, TWIST-1, miR-10b, CADM2, FAK, phosphor-AKT and the epithelial-mesenchymal transition (EMT)-related protein (N-cadherin, E-cadherin and vimentin) were analyzed by RT-qPCR, immunohistochemical staining, immunofluorescence assay or western blot, respectively. Xenograft mouse models were used to analyze the role of the FOXO3a in breast cancer.ResultsFOXO3a was down-regulated and TWIST-1 was up-regulated in breast cancer tissues. Overexpression of FOXO3a or knockdown of TWIST-1 suppressed the proliferation, invasion, migration and EMT of breast cancer cells. Overexpression of TWIST-1 could reverse the effect of FOXO3a on the proliferation, invasion, migration and EMT of breast cancer. Moreover, FOXO3a suppressed the growth and metastasis of breast cancer by targeting TWIST1 in vivo.ConclusionFOXO3a inhibited the EMT and metastasis of breast cancer via TWIST-1/miR-10b/CADM2 axis.     

miR-375 targets the p53 gene to regulate cellular response to ionizing radiation and etoposide in gastric cancer cells

MicroRNAs (miRNAs) offer a new approach for molecular classification and individual therapy of human cancer due to their regulation of oncogenic pathways. In a previous report, elevated miR-375 was found in recurring gastric cancer, and it was predicted that miR-375 may be a regulator of p53 gene. However, its biological role and mechanism of actions remain unknown. In this study, we characterized the expression level of miR-375 in gastric cancer cell lines – BGC823, MGC803, SGC7901, AGS, N87, MKN45 – using RT-PCR. We found that exogenous expression of miR-375 promoted the growth of AGS cells in both liquid and soft agar media. In agreement with the previous report, overexpression of miR-375 in AGS cells reduced the p53 protein expression level. A luciferase assay demonstrated that miR-375 down-regulated p53 expression through an interaction with the 3′ UTR region of p53. In addition, the expression of miR-375 desensitizes cells to ionizing radiation and etoposide. Flow cytometry analyses showed that miR-375 abrogated the cell cycle arrest and apoptosis after DNA damage. These results demonstrate that miR-375 targets p53 to regulate the response to ionizing radiation and etoposide treatment.     

Subcellular proteomics revealed the epithelial-mesenchymal transition phenotype in lung cancer

Subcellular proteomics was used to compare the protein profiles between human lung adenocarcinoma A549 cells and human bronchial epithelial (HBE) cells. In total, 106 differential proteins were identified and the altered expression levels of partial identified proteins were confirmed by Western blot analysis. Importantly, pathway analysis and biological validation revealed epithelial-mesenchymal transition (EMT) phenotype shift in A549 cells as compared with HBE cells. The EMT phenotype of A549 cells can be increased by self-producing TGF-β1 and significantly decreased by silencing heterogeneous nuclear ribonucleoprotein (hnRNPK) expression. As EMT has been considered as an important event during malignant tumor progression and metastasis, investigating EMT and deciphering the related pathways may lead to more efficient strategies to fight lung cancer progression. By integrating the subcellular proteomic data with EMT-related functional studies, we revealed new insights into the EMT progress of lung carcinogenesis, providing clues for further investigations on the discovery of potential therapeutic targets.     

基质金属蛋白酶在乳腺癌上皮间质转化中的作用

基质金属蛋白酶(matrix metalloproteinase,MMP)能够分解并修饰细胞外基质及细胞连接,促进上皮细胞从周围组织中分离出来。在乳腺癌中MMP表达量升高,刺激肿瘤发生,引起癌症细胞的入侵和转移。上皮细胞-间质细胞转化(epithelial-mesenchymal transition,EMT)的激活与肿瘤的发生也有关。最近的研究表明MMP在乳腺的发育和致病的EMT过程中充当促进因子和介质的角色。本文主要概括最新的关于MMP是如何调节乳腺癌细胞的运动、入侵和EMT所驱动的乳腺癌发育的研究,为更好地理解MMP在乳腺癌发病过程中的作用提供依据。     

Epithelial–mesenchymal transition in cancer metastasis: Mechanisms,markers and strategies to overcome drug resistance in the clinic

Epithelial–mesenchymal transition (EMT) is a key step during embryogenesis. Accumulating evidence suggests a critical role in cancer progression, through which tissue epithelial cancers invade and metastasise. Cell characteristics are highly affected during EMT, resulting in altered cell–cell and cell–matrix interactions, cell motility and invasiveness. Nevertheless, the demonstration of this process in human cancer has been proven difficult and controversial. Besides the fact that the acquisition of mesenchymal characteristics is not a prerequisite for cell migration/invasion, it is a transient event that concerns only few cells in a tumour mass. The induction of EMT depends on the tumour type and its genetic alterations as well as on its interaction with the extracellular matrix. In parallel, trials for EMT identification in clinical samples lack of a widely accepted methodology, nomenclature and reliable markers. This review summarizes the main EMT characteristics and proposes methodologies for better analysis in vitro. It also highlights recent studies identifying cells with EMT characteristics in human cancer and proposes certain markers to identify them in tumour samples. Finally, it cites the recent literature concerning the mechanisms of drug resistance related to EMT in the context of anti-tumour therapies and proposes related new targets for therapy.     

Scutellarin inhibits hypoxia-induced epithelial-mesenchymal transition in bladder cancer cells

Scutellarin, an active component of flavonoid, displays a variety of physiological actions and has been applied for the treatment of diverse diseases including hypertension and cerebral infarction as well as cerebral thrombosis. In recent time, Scutellarin has been demonstrated to possess the anticancer activity. But the biological significance of Scutellarin in bladder cancer (BC) remains to be elucidated. In the current study, we explored the specific effect of Scutellarin on BC progression. We found that Scutellarin inhibited hypoxia-induced BC cell migration and invasion in vitro as well as suppressed hypoxia-induced BC metastasis in vivo. Moreover, Scutellarin significantly reversed hypoxia-promoted epithelial-mesenchymal transition (EMT) in BC cells and the PI3K/Akt and MAPK pathways were implicated in the suppressive effect. Taken together, we suggested the potential value of Scutellarin as a novel anticancer agent for BC treatment.     

Exposure to ionizing radiation and brain cancer incidence: The Life Span Study cohort

BackgroundIonizing radiation is a cause of cancer. This paper examines the effects of radiation dose and age at exposure on the incidence of brain cancer using data from the Life Span Study (LSS) of atomic bomb survivors.MethodsThe Radiation Effects Research Foundation website provides demographic details of the LSS population, estimated radiation doses at time of bomb in 1945, person years of follow-up and incident cancers from 1958 to 1998. We modelled brain cancer incidence using background-stratified Poisson regression, and compared the excess relative risk (ERR) per Gray (Gy) of brain dose with estimates from follow-up studies of children exposed to diagnostic CT scans.ResultsAfter exposure to atomic bomb radiation at 10 years of age the estimated ERR/Gy was 0.91 (90%CI 0.53, 1.40) compared with 0.07 (90%CI −0.27, 0.56) following exposure at age 40. Exposure at 10 years of age led to an estimated excess of 17 brain tumors per 100,000 person year (pyr) Gy by 60 years of age. These LSS estimates are substantially less than estimates based on follow-up of children exposed to CT scans.ConclusionEstimates of ERR/Gy for brain cancers in the LSS and haemangioma cohorts seem much smaller than estimates of risk for young persons in the early years after exposure to CT-scans. This could be due to reverse causation bias in the CT cohorts, diagnostic error, measurement error with radiation doses, loss of early follow-up in the LSS, or non-linearity of the dose-response curve.     

Deglycosylation of epithelial cell adhesion molecule affects epithelial to mesenchymal transition in breast cancer cells

The transmembrane glycoprotein epithelial cell adhesion molecule (EpCAM) is overexpressed in most epithelial cancers including breast cancer, where it plays an important role in cancer progression. Previous study has demonstrated that knockdown of EpCAM inhibits breast cancer cell growth and metastasis via inhibition of the Ras/Raf/ERK signaling pathway and matrix metallopeptidase-9 (MMP-9). Although glycosylation is believed to be associated with the function of EpCAM, the contribution of N-glycosylation to this function remains unclear. We constructed the N-glycosylation mutation plasmid of EpCAM and used it to treat breast cancer cells. Loss of N-glycosylation at all three sites EpCAM had no effect on its level of expression or membrane localization. However, mutation at glycosylation sites significantly reduced the ability of EpCAM to promote epithelial to mesenchymal transition in breast cancer. N-glycosylation mutation of EpCAM led to decrease phosphorylation of Raf, ERK, and Akt, and inhibited the Ras/Raf/ERK and PI3K/Akt signaling pathways. Furthermore, we demonstrated that N-glycosylation mutation of EpCAM-mediated invasion and metastasis of breast carcinoma cells required the downregulation of MMP-9 via inhibition of these two signaling pathways. Our results identified the characteristics and function of EpCAM glycosylation. These data could illuminate molecular regulation of EpCAM by glycosylation and promote our understanding of the application of glycosylated EpCAM as a target for breast cancer therapy.     

Molecular monitoring of epithelial-to-mesenchymal transition in breast cancer cells by means of Raman spectroscopy

In breast cancer the presence of cells undergoing the epithelial-to-mesenchymal transition is indicative of metastasis progression. Since metabolic features of breast tumour cells are critical in cancer progression and drug resistance, we hypothesized that the lipid content of malignant cells might be a useful indirect measure of cancer progression. In this study Multivariate Curve Resolution was applied to cellular Raman spectra to assess the metabolic composition of breast cancer cells undergoing the epithelial to mesenchymal transition. Multivariate Curve Resolution analysis led to the conclusion that this transition affects the lipid profile of cells, increasing tryptophan but maintaining a low fatty acid content in comparison with highly metastatic cells. Supporting those results, a Partial Least Square-Discriminant analysis was performed to test the ability of Raman spectroscopy to discriminate the initial steps of epithelial to mesenchymal transition in breast cancer cells. We achieved a high level of sensitivity and specificity, 94% and 100%, respectively. In conclusion, Raman microspectroscopy coupled with Multivariate Curve Resolution enables deconvolution and tracking of the molecular content of cancer cells during a biochemical process, being a powerful, rapid, reagent-free and non-invasive tool for identifying metabolic features of breast cancer cell aggressiveness at first stages of malignancy.     

Induction of apoptosis by ionizing radiation and CI-1033 in HuCCT-1 cells

CI-1033 is a quinazoline-based HER family tyrosine kinase inhibitor that is currently being evaluated as a potential anticancer agent. The present study examines the molecular mechanism by which CI-1033 induces apoptosis either as a single agent or in combination with radiation. Although CI-1033 alone did not induce apoptosis, the simultaneous exposure of cells to CI-1033 and radiation induced significant levels of apoptosis. The sequential treatment of cells with CI-1033 followed by radiation induced an even greater effect with 62.6% of cells undergoing apoptosis but this enhanced effect was not seen if cells were treated first with radiation and then CI-1033. The combination treatment induces apoptosis of HuCCT-1 via upregulation of FasL and Bid cleavage. These data suggest that modulation of the Fas-FasL pathway and activation of Bid could be useful for increasing the anti-tumor effect of CI-1033 in this type of cancer.     

Down-regulation of PERK enhances resistance to ionizing radiation

Although, ionizing radiation (IR) has been implicated to cause stress in endoplasmic reticulum (ER), how ER stress signaling and major ER stress sensors modulate cellular response to IR is unclear. Protein kinase RNA-like endoplasmic reticulum kinase (PERK) is an ER transmembrane protein which initiates unfolded protein response (UPR) or ER stress signaling when ER homeostasis is disturbed. Here, we report that down-regulation of PERK resulted in increased clonogenic survival, enhanced DNA repair and reduced apoptosis in irradiated cancer cells. Our study demonstrated that PERK has a role in sensitizing cancer cells to IR.