Project description:Purpose: The acquisition of cellular invasiveness of breast epithelial cells and subsequent transition from ductal carcinoma in situ (DCIS) to invasive breast cancer is a critical step in breast cancer progression. Very little is known about the molecular dynamics governing this transition. We have previously shown that overexpression of the transcriptional regulator TBX3 in DCIS-like 21NT cells results in increased survival, growth, and invasiveness. In this study we explore the role of TBX3 in breast cancer progression pathways, focusing specifically on its involvement in the induction of EMT and the transition from DCIS to invasive mammary carcinoma. Methods: Total mRNA was isolated from 21NT transfected cell lines. Sequencing was conducted using an Illumina HiSeq 2500 sequencer, comparing the resultant transcriptional profiles with overexpression of either TBX3 isoform (TBX3iso1 or TBX3iso2) as fold changes relative to the empty vector control. RNA-Seq data was integrated with ChIP-array data downstream to assess direct targets of TBX3 isoforms and relate it to the process of EMT. TBX3, SLUG and TWIST1 expression were assessed by immunohistochemistry in two independent early-stage (Stage 0 and Stage 1) breast cancer cohorts. Results: An EMT-related transcriptional profile was observed with overexpression of TBX3iso1 and TBX3iso2. Using genome-wide bioinformatic approaches in conjunction with more conventional in vitro studies, we have identified SLUG and TWIST1 as downstream targets of TBX3 and have assessed their expression by immunohistochemistry in two different patient cohorts. Our findings suggest that TBX3 facilitates the process of early invasion in DCIS lesions by promoting the induction of EMT and tumor progression through the low-grade pathway. Finally, we propose a progression model in which SLUG is an important and necessary effector downstream of TBX3, leading to increased motility, invasiveness, and induction of key invasiveness-associated genes. Conclusions: This is the only existing study which has conducted assessment of transcriptional changes associated with TBX3 isoforms (TBX3iso1 and TBX3iso2). Our published study has identified the transcriptional regulator TBX3 as an enabler of EMT in non-high grade, pre-invasive lesions of the breast, inducing SLUG and promoting the transition from in situ (DCIS) to invasive breast cancer.

Project description:Pathologic and epidemiologic evidence has led to a histologic model of breast cancer progression that involves advancement through specific morphologic stages including atypical ductal hyperplasia (ADH), ductal carcinoma in situ (DCIS) and invasive mammary carcinoma (IMC), although not necessarily always in a linear fashion. Numerous observational studies have examined genetic, epigenetic and gene expression differences in breast tissues representing these different stages of progression, but model systems which would allow for experimental testing of specific factors influencing transition through these stages are scarce. The 21T series cell lines, all originally derived from the same patient with metastatic breast cancer, have been proposed to represent a mammary tumor progression series. We report here that three of the 21T cell lines indeed mimic specific stages of human breast cancer progression (21PT-derived cells, ADH; 21NT-derived cells, DCIS; 21MT-1 cells, IMC) when grown in the mammary fat pad of nude mice, albeit after up to a year post-injection. In order to develop a more rapid, readily manipulatable in vitro assay for examining the biologic differences between these cell lines, we have made use of a 3D Matrigel system. When grown in 3D Matrigel, we have found characteristic morphologies of the three cell lines in which quantifiable aspects of the stage-specific in vivo behaviors (i.e. differences in acinar structure formation, cell polarization, cell cohesiveness, cell proliferation, cell invasion) are re-capitulated in a reproducible fashion. Gene expression profiling has revealed a characteristic pattern for each of the three cell lines. Interestingly, WNT pathway alterations are particularly predominant in the early transition from 21PTci (ADH) to 21NTci (DCIS), whereas alterations in expression of genes associated with control of cell motility and invasiveness phenomena are more prominent in the later transition of 21NTci (DCIS) to 21MT-1 (IMC). This system thus reveals potential therapeutic targets and will provide a means of testing the influences of identified genes on transitions between these stages of pre-malignant to malignant growth. Keywords: DCIS or IDC vs ADH RNA derived from three biological replicates of a cell line representing atypical ductal hyperplasia (ADH), Ductal carcinoma in situ (DCIS), and Invasive ductal carcinoma (IDC)

Project description:Pathologic and epidemiologic evidence has led to a histologic model of breast cancer progression that involves advancement through specific morphologic stages including atypical ductal hyperplasia (ADH), ductal carcinoma in situ (DCIS) and invasive mammary carcinoma (IMC), although not necessarily always in a linear fashion. Numerous observational studies have examined genetic, epigenetic and gene expression differences in breast tissues representing these different stages of progression, but model systems which would allow for experimental testing of specific factors influencing transition through these stages are scarce. The 21T series cell lines, all originally derived from the same patient with metastatic breast cancer, have been proposed to represent a mammary tumor progression series. We report here that three of the 21T cell lines indeed mimic specific stages of human breast cancer progression (21PT-derived cells, ADH; 21NT-derived cells, DCIS; 21MT-1 cells, IMC) when grown in the mammary fat pad of nude mice, albeit after up to a year post-injection. In order to develop a more rapid, readily manipulatable in vitro assay for examining the biologic differences between these cell lines, we have made use of a 3D Matrigel system. When grown in 3D Matrigel, we have found characteristic morphologies of the three cell lines in which quantifiable aspects of the stage-specific in vivo behaviors (i.e. differences in acinar structure formation, cell polarization, cell cohesiveness, cell proliferation, cell invasion) are re-capitulated in a reproducible fashion. Gene expression profiling has revealed a characteristic pattern for each of the three cell lines. Interestingly, WNT pathway alterations are particularly predominant in the early transition from 21PTci (ADH) to 21NTci (DCIS), whereas alterations in expression of genes associated with control of cell motility and invasiveness phenomena are more prominent in the later transition of 21NTci (DCIS) to 21MT-1 (IMC). This system thus reveals potential therapeutic targets and will provide a means of testing the influences of identified genes on transitions between these stages of pre-malignant to malignant growth. Keywords: DCIS or IDC vs ADH

Project description:DCIS is a non-invasive precursor lesion to invasive breast carcinoma. We still have no understanding on why only some DCIS lesions evolve to invasive cancer while others appear not to do so during the life span of the patient. Here, we performed full exome (tumor vs. matching normal), transcriptome and methylome analysis of 30 pure high-grade DCIS (HG-DCIS) and 10 normal breast epithelial samples. Sixty two percent of HG-DCIS cases displayed mutations affecting cancer driver genes or potential drivers. Mutations were observed affecting PIK3CA (21% of cases), TP53 (17%), GATA3 (7%), MLL3 (7%) and single cases of mutations affecting CDH1, MAP2K4, TBX3, NF1, ATM and ARID1A. Significantly, 83% of lesions displayed numerous large chromosomal copy number alterations, suggesting they might precede selection of cancer driver mutations. Integrated pathway-based modeling analysis of RNA-seq data allowed us to identify two DCIS subgroups (DCIS-C1 and DCIS-C2) based on their tumor intrinsic subtypes, proliferative, immune scores and in the activity of specific signaling pathways. The more aggressive DCIS-C1 (highly proliferative, basal-like or ERBB2+) displayed signatures characteristic of activated Treg cells (CD4+/CD25+/FOXP3+) and CTLA4+/CD86+ complexes indicative of a tumor-associated immune suppressive phenotype. Strikingly, all lesions showed evidence of TP53 pathway inactivation. Similarly ncRNA and methylation profiles reproduce changes observed post-invasion. Among the most significant findings we observed upregulation of lncRNA HOTAIR in DCIS-C1 lesions and hypermethylation of HOXA5 and specific SOX genes. We conclude that most HG-DCIS lesions, in spite of representing a pre-invasive stage of tumor progression, displayed molecular profiles indistinguishable from invasive breast cancer. RNAs from 25 out of 30 (83%) pure HG-DCIS and 10 normal breast organoids (total 35 samples) were subjected to RNA-Seq analysis by using Illumina HiSeq2000 platform Please note that description of samples employed for the NGS analyses including age, race, ER/PR immunohistochemistry results, ITIL/STIL scores and PAM50 classification is provided the 'Supplementary Data1_Samples data.xlsx' (available on Superseries record)

Project description:DCIS is a non-invasive precursor lesion to invasive breast carcinoma. We still have no understanding on why only some DCIS lesions evolve to invasive cancer while others appear not to do so during the life span of the patient. Here, we performed full exome (tumor vs. matching normal), transcriptome and methylome analysis of 30 pure high-grade DCIS (HG-DCIS) and 10 normal breast epithelial samples. Sixty two percent of HG-DCIS cases displayed mutations affecting cancer driver genes or potential drivers. Mutations were observed affecting PIK3CA (21% of cases), TP53 (17%), GATA3 (7%), MLL3 (7%) and single cases of mutations affecting CDH1, MAP2K4, TBX3, NF1, ATM and ARID1A. Significantly, 83% of lesions displayed numerous large chromosomal copy number alterations, suggesting they might precede selection of cancer driver mutations. Integrated pathway-based modeling analysis of RNA-seq data allowed us to identify two DCIS subgroups (DCIS-C1 and DCIS-C2) based on their tumor intrinsic subtypes, proliferative, immune scores and in the activity of specific signaling pathways. The more aggressive DCIS-C1 (highly proliferative, basal-like or ERBB2+) displayed signatures characteristic of activated Treg cells (CD4+/CD25+/FOXP3+) and CTLA4+/CD86+ complexes indicative of a tumor-associated immune suppressive phenotype. Strikingly, all lesions showed evidence of TP53 pathway inactivation. Similarly ncRNA and methylation profiles reproduce changes observed post-invasion. Among the most significant findings we observed upregulation of lncRNA HOTAIR in DCIS-C1 lesions and hypermethylation of HOXA5 and specific SOX genes. We conclude that most HG-DCIS lesions, in spite of representing a pre-invasive stage of tumor progression, displayed molecular profiles indistinguishable from invasive breast cancer. DNA from 24 out of 30 (80%) HG-DCIS samples and 5 normal breast organoids (total 29 samples) were subjected to reduced representation bisulfite sequencing analysis (RRBS) by using Illumina HiSeq2000 platform. Please note that description of samples employed for the NGS analyses including age, race, ER/PR immunohistochemistry results, ITIL/STIL scores and PAM50 classification is provided the 'Supplementary Data1_Samples data.xlsx' (available on Superseries record)

Project description:Background: Ductal carcinoma in situ (DCIS) is the most common type of in situ premalignant breast cancers. What drives DCIS to invasive breast cancer is unclear. Basal-like invasive breast cancers are aggressive. We have previously shown that N-Ras is highly expressed selectively in basal-like subtypes of invasive breast cancers and can promote their growth and progression. In this study, we investigated whether NRAS expression at the DCIS stage can control transition from luminal DCIS to basal-like invasive breast cancers. Methods: Wilcoxon rank-sum test was performed to assess expression of NRAS in DCIS compared to invasive breast tumors in patients. NRAS levels were also determined by fluorescence in situ hybridization in patient tumor microarrays (TMAs) with concurrent normal, DCIS, and invasive breast cancer, and association of NRAS mRNA levels with DCIS and invasive breast cancer was assessed by paired Wilcoxon signed-rank test. Pearson’s correlation was calculated between NRAS mRNA levels and basal biomarkers in the TMAs, as well as in patient datasets. RNA-seq data was generated in cell lines and unsupervised hierarchical clustering was performed after combining with RNA-seq data from a previously published patient cohort. Results: Invasive breast cancers showed higher NRAS mRNA levels compared to DCIS samples. These NRAShigh lesions were also enriched with basal-like features, such as basal gene expression signatures, lower ER, and higher p53 protein and Ki67 levels. We have shown previously that N-Ras drives aggressive features in DCIS-like and basal-like SUM102PT cells. Here, we found that NRAS-silencing induced a shift to a luminal gene expression pattern. Conversely, NRAS overexpression in the luminal DCIS SUM225 cells induced a basal-like gene expression pattern, as well as an epithelial-to-mesenchymal transition signature. Furthermore, these cells formed disorganized mammospheres containing cell masses with an apparent reduction in adhesion. Conclusions: These data suggest that elevated NRAS levels in DCIS is not only a marker but can also control the emergence of basal-like features leading to more aggressive tumor activity, thus supporting the therapeutic hypothesis that targeting N-Ras and/or downstream pathways may block disease progression for a subset of DCIS patients with high NRAS.

Dataset Information

Transcriptional changes associated with overexpression of TBX3 isoforms (TBX3iso1 and TBX3iso2) in the DCIS-like 21NT cell line (ChIP)

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