Dataset Information

Re-expression of miR-200s in claudin-low mammary tumor cells alters cell shape and reduces proliferation and invasion potentially through modulating other miRNAs and SUZ12 regulated genes.

ABSTRACT:

Background

MicroRNAs are a class of non-coding RNAs that regulate gene expression through binding to mRNAs and preventing their translation. One family of microRNAs known as the miR-200 family is an important regulator of epithelial identity. The miR-200 family consists of five members expressed in two distinct clusters; the miR-200c/141 cluster and the miR-200b/200a/429 cluster. We have found that murine and human mammary tumor cells with claudin-low characteristics are associated with very low levels of all five miR-200s.

Methods

To determine the impact of miR-200s on claudin-low mammary tumor cells, the miR-200c/141 cluster and the miR-200b/200a/429 cluster were stably re-expressed in murine (RJ423) and human (MDA-MB-231) claudin-low mammary tumor cells. Cell proliferation and migration were assessed using BrdU incorporation and transwell migration across Matrigel coated inserts, respectively. miRNA sequencing and RNA sequencing were performed to explore miRNAs and mRNAs regulated by miR-200 re-expression while Enrichr-based pathway analysis was utilized to identify cellular functions modified by miR-200s.

Results

Re-expression of the miR-200s in murine and human claudin-low mammary tumor cells partially restored an epithelial cell morphology and significantly inhibited proliferation and cell invasion in vitro. miRNA sequencing and mRNA sequencing revealed that re-expression of miR-200s altered the expression of other microRNAs and genes regulated by SUZ12 providing insight into the complexity of miR-200 function. SUZ12 is a member of the polycomb repressor complex 2 that suppresses gene expression through methylating histone H3 at lysine 27. Flow cytometry confirmed that re-expression of miR-200s increased histone H3 methylation at lysine 27.

Conclusions

Re-expression of miR-200s in claudin-low mammary tumor cells alters cell morphology and reduces proliferation and invasion, an effect potentially mediated by SUZ12-regulated genes and other microRNAs.

SUBMITTER: Simpson K

PROVIDER: S-EPMC7863273 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Publications

Re-expression of miR-200s in claudin-low mammary tumor cells alters cell shape and reduces proliferation and invasion potentially through modulating other miRNAs and SUZ12 regulated genes.

Simpson K K Conquer-van Heumen G G Watson K L KL Roth M M Martin C J CJ Moorehead R A RA

Cancer cell international 20210204 1

<h4>Background</h4>MicroRNAs are a class of non-coding RNAs that regulate gene expression through binding to mRNAs and preventing their translation. One family of microRNAs known as the miR-200 family is an important regulator of epithelial identity. The miR-200 family consists of five members expressed in two distinct clusters; the miR-200c/141 cluster and the miR-200b/200a/429 cluster. We have found that murine and human mammary tumor cells with claudin-low characteristics are associated with ...[more]

PMID: 33541373

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Project description:BackgroundOsteopontin is a secreted phosphoglycoprotein that is expressed by a number of normal cells as well as a variety of tumor cells. With respect to breast cancer, osteopontin has been implicated in regulating tumor cell proliferation and migration/metastasis and may serve as a prognostic indicator. However it remains unclear whether osteopontin has the same impact in all breast cancer subtypes and in particular, osteopontin's effects in claudin-low breast cancer are poorly understood.MethodscDNA microarrays and qRT-PCR were used to evaluate osteopontin expression in mammary tumors from MTB-IGFIR transgenic mice and cell lines derived from these tumors. siRNA was then used to determine the impact of osteopontin knockdown on proliferation, apoptosis and migration in vitro in two murine claudin-low cell lines as well as identify the receptor mediating osteopontin's physiologic effects.ResultsOsteopontin was expressed at high levels in mammary tumors derived from MTB-IGFIR transgenic mice compared to normal mammary tissue. Evaluation of cell lines derived from different mammary tumors revealed that mammary tumor cells with claudin-low characteristic expressed high levels of osteopontin whereas mammary tumor cells with mixed luminal and basal-like features expressed lower levels of osteopontin. Reduction of osteopontin levels using siRNA significantly reduced proliferation and migration while increasing apoptosis in the claudin-low cell lines. Osteopontin's effect appear to be mediated through a receptor containing ITGAV and not through CD44.ConclusionsOur data suggests that mammary tumors with a mixed luminal/basal-like phenotype express high levels of osteopontin however this osteopontin appears to be largely produced by non-tumor cells in the tumor microenvironment. In contrast tumor cells with claudin-low characteristics express high levels of osteopontin and a reduction of osteopontin in these cells impaired proliferation, survival and migration.

Project description:BackgroundClaudin-low breast cancer is a molecular subtype associated with poor prognosis and without targeted treatment options. The claudin-low subtype is defined by certain biological characteristics, some of which may be clinically actionable, such as high immunogenicity. In mice, the medroxyprogesterone acetate (MPA) and 7,12-dimethylbenzanthracene (DMBA)-induced mammary tumor model yields a heterogeneous set of tumors, a subset of which display claudin-low features. Neither the genomic characteristics of MPA/DMBA-induced claudin-low tumors nor those of human claudin-low breast tumors have been thoroughly explored.MethodsThe transcriptomic characteristics and subtypes of MPA/DMBA-induced mouse mammary tumors were determined using gene expression microarrays. Somatic mutations and copy number aberrations in MPA/DMBA-induced tumors were identified from whole exome sequencing data. A publicly available dataset was queried to explore the genomic characteristics of human claudin-low breast cancer and to validate findings in the murine tumors.ResultsHalf of MPA/DMBA-induced tumors showed a claudin-low-like subtype. All tumors carried mutations in known driver genes. While the specific genes carrying mutations varied between tumors, there was a consistent mutational signature with an overweight of T>A transversions in TG dinucleotides. Most tumors carried copy number aberrations with a potential oncogenic driver effect. Overall, several genomic events were observed recurrently; however, none accurately delineated claudin-low-like tumors. Human claudin-low breast cancers carried a distinct set of genomic characteristics, in particular a relatively low burden of mutations and copy number aberrations. The gene expression characteristics of claudin-low-like MPA/DMBA-induced tumors accurately reflected those of human claudin-low tumors, including epithelial-mesenchymal transition phenotype, high level of immune activation, and low degree of differentiation. There was an elevated expression of the immunosuppressive genes PTGS2 (encoding COX-2) and CD274 (encoding PD-L1) in human and murine claudin-low tumors.ConclusionsOur findings show that the claudin-low breast cancer subtype is not demarcated by specific genomic aberrations, but carries potentially targetable characteristics warranting further research.

Dataset Information

Re-expression of miR-200s in claudin-low mammary tumor cells alters cell shape and reduces proliferation and invasion potentially through modulating other miRNAs and SUZ12 regulated genes.

Background

Methods

Results

Conclusions

Publications

Re-expression of miR-200s in claudin-low mammary tumor cells alters cell shape and reduces proliferation and invasion potentially through modulating other miRNAs and SUZ12 regulated genes.

Similar Datasets

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