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Inhibitory activity of YKL-40 in mammary epithelial cell differentiation and polarization induced by lactogenic hormones: a role in mammary tissue involution.

ABSTRACT: We previously reported that a secreted glycoprotein YKL-40 acts as an angiogenic factor to promote breast cancer angiogenesis. However, its functional role in normal mammary gland development is poorly understood. Here we investigated its biophysiological activity in mammary epithelial development and mammary tissue morphogenesis. YKL-40 was expressed exclusively by ductal epithelial cells of parous and non-parous mammary tissue, but was dramatically up-regulated at the beginning of involution. To mimic ductal development and explore activity of elevated YKL-40 during mammary tissue regression in vivo, we grew a mammary epithelial cell line 76N MECs in a 3-D Matrigel system in the presence of lactogenic hormones including prolactin, hydrocortisone, and insulin. Treatment of 76N MECs with recombinant YKL-40 significantly inhibited acinar formation, luminal polarization, and secretion. YKL-40 also suppressed expression of E-cadherin but increased MMP-9 and cell motility, the crucial mechanisms that mediate mammary tissue remodeling during involution. In addition, engineering of 76N MECs with YKL-40 gene to express ectopic YKL-40 recapitulated the same activities as recombinant YKL-40 in the inhibition of cell differentiation. These results suggest that YKL-40-mediated inhibition of cell differentiation and polarization in the presence of lactogenic hormones may represent its important function during mammary tissue involution. Identification of this biophysiological property will enhance our understanding of its pathologic role in the later stage of breast cancer that is developed from poorly differentiated and highly invasive cells.

SUBMITTER: Scully S

PROVIDER: S-EPMC3185048 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature

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Inhibitory activity of YKL-40 in mammary epithelial cell differentiation and polarization induced by lactogenic hormones: a role in mammary tissue involution.

Scully Steve S Yan Wei W Bentley Brooke B Cao Qing Jackie QJ Shao Rong R

PloS one 20111003 10

We previously reported that a secreted glycoprotein YKL-40 acts as an angiogenic factor to promote breast cancer angiogenesis. However, its functional role in normal mammary gland development is poorly understood. Here we investigated its biophysiological activity in mammary epithelial development and mammary tissue morphogenesis. YKL-40 was expressed exclusively by ductal epithelial cells of parous and non-parous mammary tissue, but was dramatically up-regulated at the beginning of involution. ...[more]

PMID: 21991364

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Project description:The development of mammary gland as a lactogenic tissue is a highly coordinated multistep process. The epithelial cells of lactiferous tubules undergo profound changes during the developmental window of puberty, pregnancy, and lactation. Several hormones including estrogen, progesterone, glucocorticoids and prolactin act in concert, and orchestrate the development of mammary gland. Understanding the gene regulatory networks that coordinate proliferation and differentiation of HC11 Mammary Epithelial stem-like Cells (MEC) under the influence of lactogenic hormones is critical for elucidating the mechanism of lactogenesis in detail. In this study, we analyzed transcriptome profiles of undifferentiated MEC (normal) and compared them with Murine Embryonic Stem Cells (ESC) using next-generation mRNA sequencing. Further, we analyzed the transcriptome output during lactogenic differentiation of MEC following treatment with glucocorticoids (primed state) and both glucocorticoids and prolactin together (prolactin state). We established stage-specific gene regulatory networks in ESC and MEC (normal, priming and prolactin states). We validated the top up-and downregulated genes in each stage of differentiation of MEC by RT-PCR and found that they are comparable with that of RNA-seq data. HC11 MEC display decreased expression of Pou5f1 and Sox2, which is crucial for the differentiation of MEC, which otherwise ensure pluripotency to ESC. Cited4 is induced during priming and is involved in milk secretion. MEC upon exposure to both glucocorticoids and prolactin undergo terminal differentiation, which is associated with the expression of several genes, including Xbp1 and Cbp that are required for cell growth and differentiation. Our study also identified differential expression of transcription factors and epigenetic regulators in each stage of lactogenic differentiation. We also analyzed the transcriptome data for the pathways that are selectively activated during lactogenic differentiation. Further, we found that selective expression of chromatin modulators (Dnmt3l, Chd9) in response to glucocorticoids suggests a highly coordinated stage-specific lactogenic differentiation of MEC.

Project description:Purpose: Understanding of gene transcriptional networks specifying murine mammary epithelial cells (HC11) during lactogenic differentiation and its comparision with murine embryonic stem cells Methods: RNA-sequencing after ribosomal RNA depletion followed by cDNA synthesis, adaptor ligation and sequencing in duplicate of each sample using Illumina Hi-seq 2500 paired end sequencing. Sequence reads with adapters, over-represented and low-quality reads were discarded. High quality reads were mapped to reference mouse genome (mm10) using Bowtie followed derivation of FPKM values using cufflinks and DE-seq to observe differentially expressed genes. Results: Using standard analysis methods which were published recently we uniquely mapped more than 50 million sequence reads out of which total 11961 transcripts were from ESC, 11045 from Normal, 11243 from Primed and 10719 from prolactin stage. When we did DE-seq differential gene expression analysis we observed that for Normal to primed transition 1141 and 1026 transcripts were Up and Down regulated respectively where as upon transition from Primed to Prolactin stage 385 and 655 transcripts were Up and Down regulated respectively. We also did pathway analysis to interpret the transcript activation and its function during lactogeinc differentiation; we found that the pathways which are highly up regulated are related to carbohydrate, lipids, nucleic acid and protein metabolism. We also observed that most of the up regulated pathways were related to maintenance of mammary cells differentiated state and nutrition of the infants. Our study concludes that overall differentiation requires priming with glucocorticoids followed by prolactin stimulation of HC11 cells, which tunes the cells for the secretion of milk and its maintenance of the differentiated state till the lactation period. Conclusions: Transcriptome analysis by next generation sequencing allowed us to explore global gene expression during lactogenic differentiation of HC11 cells in presence of glucocortiocids in primed state. Glucocorticoids are activating genes, transcription factors, epigenetic modifiers and metabolic pathways which are required for later stages of lactation. On other hand gene expression analysis of prolactin stage revealed that there is a focused gene expression exclusively related to lactation process. We also observed that HC11 stem like marker are highly expressed in undifferentiated state whose expression was down regulated in primed and prolactin state indicating that HC11 are partially bipotent cells; when these cells receive differentiation signals they loose their stem cell like characteristics and are differentiated.

Dataset Information

Inhibitory activity of YKL-40 in mammary epithelial cell differentiation and polarization induced by lactogenic hormones: a role in mammary tissue involution.

Publications

Inhibitory activity of YKL-40 in mammary epithelial cell differentiation and polarization induced by lactogenic hormones: a role in mammary tissue involution.

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