Project description:MiR-544 was inhibited by either a miR-544 antagomir or compound 1 under hypoxic conditions in MDA-MB-231 cells MiRNA microarray was utilized to examine the specificity of 1 for miR-544. 3 MDA-MB-231 samples treated with a miR-544 antagomir or compound 1 were subjected to hypoxia for a period of 5 days. After 5 days, samples were pooled and subjected to miRNA microarray analysis.
Project description:"We have reported that the nuclear protein high mobility group A2 (HMGA2), is required for the induction of EMT by TGF-beta (Thuault et al. J. Cell Biol. 2006). HMGA2 regulates a cohort of transcriptional regulators of the EMT process, such as Snail1 and Twist1 (Thuault et al. J. Biol. Chem. 2008, E-Jean Tan et al. J. Biol. Chem. 2012). Since HMGA2 is a chromatin-associated protein, we expect that it should regulate many genes in addition to the EMT-related factors. The aim of our study is to decipher novel molecular mechanisms that explain how EMT links to the process of tumor-initiating cell self-renewal via the chromatin factor HMGA2. In this experiment, we stably transfected human breast cancer MDA-MB-231 cells with shRNA against HMGA2 and investigated effects of the knock-down on global gene expression using Affymetrix arrays, in order to identify novel downstream players involved in this network. In parallel experiments we also analyzed the phenotypic effects of the HMGA2 knock-down on MDA-MB-231 cell proliferation, survival and inavasiveness."
Project description:Glycerol-3-phosphate acyltransferase-2 is a member of "cancer-testis gene" family. Initially linked to lipid metabolism, this gene has been recently found involved also in PIWI-interacting RNAs biogenesis in germline stem cells. To investigate its role in piRNA metabolism in cancer, the gene was silenced in MDA-MB-231 breast cancer cells and small RNA sequencing was applied. PIWI-interacting RNAs and tRNA-derived fragments expression profiles showed changes following GPAT2 silencing. Interestingly, a marked shift in length distribution for both small RNAs was detected in GPAT2-silenced cells. Most downregulated PIWI-interacting RNAs are single copy in the genome, intragenic, hosted in snoRNAs and previously found to be upregulated in cancer cells. Putative targets of these PIWI-interacting RNAs are linked to lipid metabolism. Downregulated tRNA derived fragments derived from, so-called 'differentiation tRNAs', whereas upregulated ones derived from proliferation-linked tRNAs. miRNA amounts decrease after Glycerol-3-phosphate acyltransferase-2 silencing and functional enrichment analysis of deregulated miRNA putative targets point to mitochondrial biogenesis, IGF1R signaling and oxidative metabolism of lipids and lipoproteins. In addition, miRNAs known to be overexpressed in breast cancer tumors with poor prognosis where found downregulated in GPAT2-silenced cells. In conclusion, GPAT2 silencing quantitatively and qualitatively affects the population of PIWI-interacting RNAs, tRNA derived fragments and miRNAs which, in combination, result in a more differentiated cancer cell phenotype.
Project description:Analysis of the effect of FoxA1 on gene expression in molecular apocrine breast tumours, by silencing FoxA1 and measuring expression change against a control sample.
Project description:MiR-544 was inhibited by either a miR-544 antagomir or compound 1 under hypoxic conditions in MDA-MB-231 cells U133 Plus 2.0 microarray was utilized to examine the specificity of 1 for miR-544. 3 MDA-MB-231 samples treated with a miR-544 antagomir or compound 1 were subjected to hypoxia for a period of 5 days. After 5 days, samples were pooled and subjected to gene level microarray analysis.
Project description:Breast cancer remains a leading cause of death in women worldwide. Although breast cancer therapies have greatly advanced in recent years, many patients still develop tumour recurrence and metastasis, and eventually succumb to the disease due to chemoresistance. Citral has been reported to show cytotoxic effect on various cancer cell lines. However, the potential of citral to specifically target the drug resistant breast cancer cells has not yet been tested, which was the focus of our current study.The cytotoxic activity of citral was first tested on MDA-MB-231 cells in vitro by MTT assay. Subsequently, spheroids of MDA-MB-231 breast cancer cells were developed and treated with citral at different concentrations. Doxorubicin, cisplatin and tamoxifen were used as positive controls to evaluate the drug resistance phenotype of MDA-MB-231 spheroids. In addition, apoptosis study was performed using AnnexinV/7AAD flowcytometry. Aldefluor assay was also carried out to examine whether citral could inhibit the ALDH-positive population, while the potential mechanism of the effect of citral was carried out by using quantitative real time- PCR followed by western blotting analysis.Citral was able to inhibit the growth of the MDA-MB-231 spheroids when compared to a monolayer culture of MDA-MB-231 cells at a lower IC50 value. To confirm the inhibition of spheroid self-renewal capacity, the primary spheroids were then cultured to additional passages in the absence of citral. A significant reduction in the number of secondary spheroids were formed, suggesting the reduction of self-renewal capacity of these aldehyde dehydrogenase positive (ALDH+) drug resistant spheroids. Moreover, the AnnexinV/7AAD results demonstrated that citral induced both early and late apoptotic changes in a dose-dependent manner compared to the vehicle control. Furthermore, citral treated spheroids showed lower cell renewal capacity compared to the vehicle control spheroids in the mammosphere formation assay. Gene expression studies using quantitative real time PCR and Western blotting assays showed that citral was able to suppress the self-renewal capacity of spheroids and downregulate the Wnt/?-catenin pathway.The results suggest that citral could be a potential new agent which can eliminate drug-resistant breast cancer cells in a spheroid model via inducing apoptosis.
Project description:Breast cancer is the most common cancer and the second leading cause of cancer death in industrialized countries. Systemic treatment of breast cancer is effective at the beginning of therapy. However, after a variable period of time, progression occurs due to therapy resistance. Artesunate, clinically used as anti-malarial agent, has recently revealed remarkable anti-tumor activity offering a role as novel candidate for cancer chemotherapy. We analyzed the anti-tumor effects of artesunate in metastasizing breast carcinoma in vitro and in vivo. Unlike as expected, artesunate induced resistance in highly metastatic human breast cancer cells MDA-MB-231. Likewise acquired resistance led to abolishment of apoptosis and cytotoxicity in pre-treated MDA-MB-231 cells. In contrast, artesunate was more cytotoxic towards the less tumorigenic MDA-MB-468 cells without showing resistance. Unraveling the underlying molecular mechanisms, we found that resistance was induced due to activation of the tumor progression related transcription factors NFκB and AP-1. Thereby transcription, expression and activity of the matrix-degrading enzyme MMP-1, whose function is correlated with increased invasion and metastasis, was up-regulated upon acquisition of resistance. Additionally, activation of the apoptosis-related factor NFκB lead to increased expression of ant-apoptotic bcl2 and reduced expression of pro-apoptotic bax. Application of artesunate in vivo in a model of xenografted breast cancer showed, that tumors growth was not efficiently abolished as compared to the control drug doxorubicin. Taken together our in vitro and in vivo results correlate well showing for the first time that artesunate induces resistance in highly metastatic breast tumors.
Project description:Since bone metastatic breast cancer is an incurable disease, causing significant morbidity and mortality, understanding of the underlying molecular mechanisms would be highly valuable. Here, we describe in vitro and in vivo evidence for the importance of serine biosynthesis in the metastasis of breast cancer to bone. We first characterized the bone metastatic propensity of the MDA-MB-231(SA) cell line variant as compared to the parental MDA-MB-231 cells by radiographic and histological observations in the inoculated mice. Genome-wide gene expression profiling of this isogenic cell line pair revealed that all the three genes involved in the L-serine biosynthesis pathway, phosphoglycerate dehydrogenase (PHGDH), phosphoserine aminotransferase 1 (PSAT1), and phosphoserine phosphatase (PSPH) were upregulated in the highly metastatic variant. This pathway is the primary endogenous source for L-serine in mammalian tissues. Consistently, we observed that the proliferation of MDA-MB-231(SA) cells in serine-free conditions was dependent on PSAT1 expression. In addition, we observed that L-serine is essential for the formation of bone resorbing human osteoclasts and may thus contribute to the vicious cycle of osteolytic bone metastasis. High expression of PHGDH and PSAT1 in primary breast cancer was significantly associated with decreased relapse-free and overall survival of patients and malignant phenotypic features of breast cancer. In conclusion, high expression of serine biosynthesis genes in metastatic breast cancer cells and the stimulating effect of L-serine on osteoclastogenesis and cancer cell proliferation indicate a functionally critical role for serine biosynthesis in bone metastatic breast cancer and thereby an opportunity for targeted therapeutic interventions. Parental MDA-MB-231 cells and MDA-MB-231(SA) cells were cultured in cell culture flasks. RNA was isolated in order to compare the gene expression profiles of these cell variants. Total of two samples. No replicates.
Project description:Molecular responses to MEK inhibition in cancer cells are complex and dynamic. We performed a time-series experiment to measure global RNA expression changes following treatment with the MEK inihibor U0126 MDA-MB-231 human breast cancer cells were grown in low-serum conditions. Treatment with U0126 was initiated in the presence of EGF. RNA was harvested at multiple time points during the course of 48 hours.
Project description:From our previous data, we found that loss of ATAD3A gene expression in breast cancer cells results in loss of cell motility in vitro and metastasis in vivo. To obtain a better understanding of oncogenic pathway of ATAD3A, we have established the stable ATAD3A knockdown MDA-MB-231 cells using lentiviral strategy. We used the whole genome microarrays to detail the global programme of gene expression after depleting of ATAD3A and identified distinct classes of up or down-regulated metastmir associated with breast cancer cells migration Total RNA was extracted from ATAD3A stable knockdown cells (shATAD3A) and the control cells (shGFP). The labeled RNA was hybridized on U133 plus 2.0 Array. To identify altered gene expression patterns with or without ATAD3A expression, we compared average mRNA expression levels between the ATAD3A knockdown and control MDA-MB-231 cells.