Project description:Purpose Triple negative breast cancer (TNBC) is the most aggressive breast cancer subtype with no targeted treatment available. Our previous study identified 38 TNBC-specific genes with altered expression in tumour samples compared to normal samples. This study aimed to identify whether DNA methylation contributed to these gene expression changes in the same breast cancer cohort. Additionally, we aimed to identify a whole genome methylation profile that contributes to the progression from primary breast tumour to lymph node metastasis. Methods We used the DNA of 23 primary TNBC samples, 12 matched lymph node metastases, and 11 matched normal adjacent tissues to perform 450K Illumina methylation arrays. The results were validated in an independent cohort of 70 primary TNBC samples. Results The gene expression of 16/38 TNBC-specific genes was associated with significantly altered methylation. Furthermore, altered methylation of 18 genes associated with lymph node metastasis was identified and validated in an independent cohort. Additionally, novel methylation changes between primary tumours and lymph node metastases, as well as those associated with survival were identified. Conclusion This study has shown that DNA methylation plays an important role in altered gene expression patterns of TNBC-specific genes and is the first study to perform whole genome DNA methylation analysis that includes matched lymph node metastases in this breast cancer subtype. This novel insight into the progression of TNBC to secondary cancers may provide potential prognostic indicators for this hard-to-treat breast cancer subtype. study cohort
Project description:Purpose Triple negative breast cancer (TNBC) is the most aggressive breast cancer subtype with no targeted treatment available. Our previous study identified 38 TNBC-specific genes with altered expression in tumour samples compared to normal samples. This study aimed to identify whether DNA methylation contributed to these gene expression changes in the same breast cancer cohort. Additionally, we aimed to identify a whole genome methylation profile that contributes to the progression from primary breast tumour to lymph node metastasis. Methods We used the DNA of 23 primary TNBC samples, 12 matched lymph node metastases, and 11 matched normal adjacent tissues to perform 450K Illumina methylation arrays. The results were validated in an independent cohort of 70 primary TNBC samples. Results The gene expression of 16/38 TNBC-specific genes was associated with significantly altered methylation. Furthermore, altered methylation of 18 genes associated with lymph node metastasis was identified and validated in an independent cohort. Additionally, novel methylation changes between primary tumours and lymph node metastases, as well as those associated with survival were identified. Conclusion This study has shown that DNA methylation plays an important role in altered gene expression patterns of TNBC-specific genes and is the first study to perform whole genome DNA methylation analysis that includes matched lymph node metastases in this breast cancer subtype. This novel insight into the progression of TNBC to secondary cancers may provide potential prognostic indicators for this hard-to-treat breast cancer subtype. Validation cohort (70 IDC TNBC samples)
Project description:Genome-wide DNA methylation profiles for 82 triple negative breast cancer (TNBC) samples from the Swedsh Cancerome Analysis Network - Breast (SCAN-B) cohort.
Project description:All-trans retinoic acid (atRA) regulates gene expression and is used to treat acute promyelocytic leukemia. Attempts to use atRA for breast cancer treatment without a stratification strategy have resulted in limited overall effectiveness. To identify biomarkers for the treatment of triple-negative breast cancer (TNBC) with atRA, we characterized the effects of atRA on the tumor growth of 13 TNBC cell lines. This resulted in a range of tumor growth effects that was not predictable based on the levels of retinoid signaling molecules and transcriptional responses that were mostly independent of retinoic acid response elements. Given the importance of DNA methylation in regulating gene expression, we hypothesized that differential DNA methylation could predict the response of TNBCs to atRA. We identified over 1400 CpG sites that were differentially methylated between atRA resistant and sensitive cell lines. These CpG sites predicted the response of four TNBC patient-derived xenografts to atRA treatment and we utilized these xenografts to refine the profile to 6 CpGs. We identify as many as 17% of TNBC patients who could benefit from atRA treatment. These data illustrate that differential DNA methylation of specific sites may predict the response of patient tumors to atRA treatment. This study characterizes the gene expression of 2 triple-negative patient-derived breast cancer xenografts
Project description:Background Breast cancer is the leading cause of cancer related deaths in women. Triple negative breast cancers are highly aggressive, have an overall poor prognosis and has limited therapeutic options. Previously, we have identified an environmental induced gene mdig that predicted the overall survival in breast cancer patients and regulated breast cancer cell growth, motility and invasion partially through DNA and histone methylation. Mdig’s role in breast cancer growth and motility has been revealed however a comprehensive analysis of the proteomic profile of mdig affected cells in triple negative breast cancer has not been attempted yet. Methods We applied mass spectrometry technology featuring global proteomics and post translational modifications in triple negative breast cancer cells MDA-MB-231 that were deleted for mdig via CRISPR Cas 9 gene editing. Using label-free bottom up quantitative proteomics, we compared the proteomes of wildtype control (WT) and mdig knockout (KO) MDA-MB-231 cells and identified the proteins and pathways that are significantly altered with mdig deletion. Ingenuity Pathway Analysis (IPA) platform was further used to explore the signaling pathway networks with differentially expressed proteins and identified top canonical pathways, upstream regulators, and causal disease networks. Results 904 differentially expressed (p < 0.005) proteins were identified in MDA-MB-231 cells knocked out for mdig. Post-translational modification (PTM) analysis indicated that mdig loss reduced the abundance of oxidized histidine 39 of 60S ribosomal protein L27a (q = 0.00030) whereas global abundance of di-methylated lysine containing peptides was increased (p = 0.02). Relevance Our data provides the first insight towards the protein expression pattern in breast cancer associated with a complete disruption of the mdig gene. Differentially expressed proteins between WT and KO MDA-MB-231 triple negative breast cancer cells provided substantial information regarding the key proteins, biological process and pathways that are specifically upregulated in breast cancer tumorigenicity and invasiveness. Mdig affected signaling pathways and hub molecules will benefit for the development of novel treatment strategies for the development of breast cancer therapies.
Project description:Analysis of DNA methylation changes after prolonged exposure of triple-negative breast cancer cell lines to low doses of Panobinostat (LBH589), a pan-histone deacetylase inhibitor.