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MiR-200 overexpression in colorectal cancer lines

ABSTRACT: Unsupervised classification of gene expression profiles has resulted in the identification of biologically and clinically distinct colon cancer subtypes (CCSs). The subtype that associates with poor clinical outcome displays a mesenchymal gene expression profile. No driver mutation has been identified for this category and patients are heterogeneous with regard to commonly used clinical markers. Here we report a regulatory network consisting of the miR-200 family members that tunes the majority of genes differentially expressed in the poor prognosis CCS, including genes involved in the epithelial-mesenchymal transition (EMT) process. Our data indicate that the epigenetic silencing of the miR-200 family by promoter methylation is identifying the mesenchymal CCS and is predictive of disease-free survival in this malignancy. We demonstrate that the molecular features of poor prognosis colon cancer - expression of EMT-associated genes and miR-200 promoter methylation - can already be installed at the premalignant stage, suggesting a highly malignant potential of specific colon cancer precursor lesions.

ORGANISM(S): Homo sapiens

PROVIDER: GSE65551 | GEO | 2015/09/01

SECONDARY ACCESSION(S): PRJNA274343

REPOSITORIES: GEO

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Project description:Metastatic disease is a primary cause of cancer-related death, and factors governing tumor cell metastasis have not been fully elucidated. Here we addressed this question by using tumor cell lines derived from mice that develop metastatic lung adenocarcinoma owing to expression of mutant K-ras and p53. A feature of metastasis-prone tumor cells that distinguished them from metastasis-incompetent tumor cells was plasticity in response to changes in their microenvironment. They transited reversibly between epithelial and mesenchymal states, forming highly polarized epithelial spheres in 3-dimensional culture that underwent epithelial-mesenchymal transition (EMT) following treatment with transforming growth factor-beta or injection into syngeneic mice. This plasticity was entirely dependent upon the microRNA-200 family, which decreased during EMT. Forced expression of miR-200 abrogated the capacity of these tumor cells to undergo EMT, invade, and metastasize and conferred transcriptional features of metastasis-incompetent tumor cells. We conclude that microenvironmental cues direct tumor metastasis by regulating miR-200 expression. Experiment Overall Design: Cell lines from p53R172Hâ??g/+ K-rasLA1/+ mice were derived from tumor tissues removed at autopsy from two different mice (#344 and #393). The tissues were minced, placed in culture, and passed serially in RPMI 1640 supplemented with 10% fetal bovine serum (FBS), which yielded mass populations of tumor cells derived from primary lung tumors (344P and 393P), mediastinal lymph nodes (344LN and 393LN), and a subcutaneous site (344SQ). Stable 344SQ cell lines expressing the miR-200b-200a-429 cluster or control vector were generated by transduction with lentivirus vectors. GFP positive transfectant pools were selected by growth in RPMI 1640 with 10% FBS and puromycin. RNA samples of miR-200b-200a-429 knockup versus control (from triplicate cultures of each) were processed and analyzed on Affymetrix Mouse Expression Array 430A 2.0 chips.

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MiR-200 overexpression in colorectal cancer lines

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