Project description:Genome-wide analyses have identified thousands of long non-coding RNAs (lncRNAs). Malat1 (Metastasis Associated Lung Adenocarcinoma Transcript 1) is among the most abundant lncRNAs whose expression is altered in numerous cancers. Here we report that genomic loss, as well as systemic knockdown of Malat1 using antisense oligonucleotides, in the MMTV-PyMT mouse mammary carcinoma model results in slower tumor growth accompanied by differentiation into highly cystic tumors and a significant reduction in lung metastasis. Further, Malat1 loss results in a reduction of branching morphogenesis in MMTV-PyMT and Her2/neu amplified tumor organoids consistent with the in vivo reduction in lung metastasis. At the molecular level, Malat1 knockdown results in alterations in gene expression and changes in splicing patterns of genes involved in differentiation and pro-tumorigenic signaling pathways. Together, these data indicate that the lncRNA Malat1 regulates critical processes in mammary cancer pathogenesis and represents a promising therapeutic target for inhibiting breast cancer metastasis. Transcriptome profiles of tumors and organoids after Malat1 knockdown using antisense olgonucleotides (ASOs).
Project description:Genome-wide analyses have identified thousands of long non-coding RNAs (lncRNAs). Malat1 (Metastasis Associated Lung Adenocarcinoma Transcript 1) is among the most abundant lncRNAs whose expression is altered in numerous cancers. Here we report that genomic loss, as well as systemic knockdown of Malat1 using antisense oligonucleotides, in the MMTV-PyMT mouse mammary carcinoma model results in slower tumor growth accompanied by differentiation into highly cystic tumors and a significant reduction in lung metastasis. Further, Malat1 loss results in a reduction of branching morphogenesis in MMTV-PyMT and Her2/neu amplified tumor organoids consistent with the in vivo reduction in lung metastasis. At the molecular level, Malat1 knockdown results in alterations in gene expression and changes in splicing patterns of genes involved in differentiation and pro-tumorigenic signaling pathways. Together, these data indicate that the lncRNA Malat1 regulates critical processes in mammary cancer pathogenesis and represents a promising therapeutic target for inhibiting breast cancer metastasis.
Project description:Previously, lncRNA Malat1 knockout mice were generated by insertional inactivation. By crossing this line to MMTV-PyMT mammary tumor mouse model, we produced PyMT;Malat1 wild-type (WT) and PyMT;Malat1 knockout (KO). Furthermore, we generated Malat1 transgenic mice by targeting ROSA26 locus and bred them to PyMT;Malat1 knockout mice to produce Malat1-rescued PyMT;Malat1 knockout;Malat1 transgenic animals (TG). Using mammary tumors from the three groups of animals, we performed RNA-Seq analysis to identify differentially up-regulated genes in KO tumors to find novel target genes of YAP-TEAD pathway.
Project description:Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a long non-coding RNA (lncRNA) that was first discovered as a prognostic marker for lung cancer metastasis. MALAT1 has been implicated in the tumorigenesis of numerous tumor types. To further delineate the underlying molecular mechanism, we established a high-throughput strategy to characterize the interacting proteins of MALAT1 by combining RNA pull down, quantitative proteomics, bioinformatics analysis, and experimental validation.
Project description:Long non-coding RNAs (lncRNAs) are critical regulators of mammalian gene programs. Metastasis Associated Lung Adenocarcinoma Transcript 1 (Malat1) is one of the most abundant lncRNA expressed in the mammalian genome. Here, we report that Malat1 regulates intestinal epithelial cell programs and contributes to tissue homeostasis and tumorigenesis. Global RNA interactions with DNA by deep sequencing (GRID-seq) experiments revealed Malat1 chromatin localization in intestinal epithelial cells from the wildtype small intestine.
Project description:MALAT1, an abundant lncRNA specifically localized to nuclear speckles, regulates alternative-splicing (AS). The molecular basis of its role in AS remains poorly understood. Here, we report three conserved, thermodynamically stable, parallel RNA-G-quadruplexes (rG4s) present in the 3’ region of MALAT1 which regulates this function. Using rG4 domain specific RNA-pull-down followed by mass-spectrometry, RNA-immuno-precipitation and imaging, we demonstrate the rG4 dependent localization of Nucleolin (NCL) and Nucleophosmin (NPM) to nuclear speckles. Specific G-to-A mutations that abolish rG4 structures, results in the localization loss of both the proteins from speckles. Functionally, disruption of rG4 in MALAT1 phenocopies NCL knockdown resulting in altered pre-mRNA splicing of endogenous genes. These results reveal a central role of rG4s within the 3’ region of MALAT1 orchestrating AS.
Project description:Here we show that the 5’ end and 3’ end of Malat1 are dependently and independently expressed. Loss of 5’ Malat1 up-regulates Neat1 in cis, while loss of 3’ Malat1 globally regulated gene expression in trans. Furthermore, loss of 3’ Malat1 accelerates premature aging and shortens the lifespan in mice, but loss of 5’ Malat1 produces no phenotypic changes. Mechanistically, 3’ Malat1 exerts a tight regulation of P21 that is drastically up-regulated in brain and retina upon its deletion in mice. This is very likely mediated at two different levels. One is at the mRNA level since Malat1 interacts with hnRNP A1 and hnRNP A2/B1. This is independently of P53 since it is significantly decreased upon 3’ Malat1 KO, probably due to the down-regulation of hnRNP C which has been shown to maintain P53 mRNA stability in our cell line model. The other is at the protein level through NPM, which is significantly up-regulated in 3’ Malat1 KO and which was known to decrease P21 ubiquitination and hence stabilizing of P21. These observations reveal previously unknown functions of 3’ Malat in the brain and indicates the need for more detailed understanding of highly abundant conserved lncRNAs, such as Malat1, and alarms for detailed understanding before therapeutic targeting in the future.
Project description:Dynamic interaction between prostate cancer and the bone microenvironment is a major contributor to metastasis of prostate cancer to bone. In this study we utilized an in-vitro co-culture model of PC3 prostate cancer cells and osteoblasts followed by microarray based gene expression profiling to identify previously unrecognized prostate cancer-bone microenvironment interactions. Factors secreted by PC3 cells resulted in the up-regulation of many genes in osteoblasts associated with bone metabolism and cancer metastasis, including Mmp13, Il-6 and Tgfb2, and down-regulation of Wnt inhibitor Sost. To determine whether altered Sost expression in the bone microenvironment has an effect on prostate cancer metastasis, we co-cultured PC3 cells with Sost knockout (SostKO) osteoblasts and wildtype (WT) osteoblasts and identified several genes differentially regulated between PC3-SostKO osteoblast co-cultures and PC3-WT osteoblast co-cultures. Co-culturing PC3 cells with WT osteoblasts up-regulated cancer-associated long noncoding RNA (lncRNA) MALAT1 in PC3 cells. MALAT1 expression was further enhanced when PC3 cells were co-cultured with SostKO osteoblasts and treatment with recombinant Sost down-regulated MALAT1 expression in these cells. Our results suggest that reduced Sost expression in the tumor microenvironment may promote bone metastasis by up-regulating MALAT1 in prostate cancer.
Project description:Previous studies reported that NEAT1 and its partner p54nrb are necessary for CARM1 to associate with paraspeckles and H3R26 methylation. There are also reports that CARM1 is essential for LincGET's role in guiding the ICM lineage in mouse embryos. We speculate that there may be a connection between CARM1 and lncRNA. In order to verify our guess, we conducted lncRNA-seq experiments against CARM1 control or siRNA in MDA-MB-231 cells to explore the lncRNA that may be regulated downstream of CARM1. Here, we showed that CARM1 and HIF1A co-upregulates the expression of MALAT1 in hypoxia pathway to promote carcinogenesis and metastasis in triple-negative breast cancer cells. These results indicate that there is a connection among CARM1, HIF1A and MALAT1 in triple-negative breast cancer.
Project description:Cutaneous squamous cell carcinoma (CSCC) is the most common metastatic skin cancer, and its incidence is increasing globally. In this study, metastasis-associated in lung adenocarcinoma transcript 1 (MALAT1), a long non-coding RNA, was identified to be significantly up-regulated in CSCC tumors and cell lines. We conducted RNA sequencing to characterize gene expression changes in MALAT1-silenced cutaneous squamous cell carcinoma cells (A431).