Gene expression and metastasis of somatic cell hybrids between murine fibroblast cell lines of different malignant potential

1057 Background: Tumors frequently contain cancer stem cells (CSCs) or tumor-initiating subpopulations, with an ability to self-renew and regenerate all cell types within the tumor. Basal-like breast cancers exhibit features of CSCs, including expression of surface markers, even though these cells are rare. Given the role of CSCs in the recurrence and spread of cancer, there is an urgent need to develop new therapeutic agents that target CSCs. Development of CSC-targeted drugs will be greatly facilitated by biomarkers that can identify CSCs to aid in patient selection and determination of drug response. Defining the CSCs in tumors is complicated by the high mesenchymal nature of fibroblasts. Analysis of gene expression and alternative splicing patterns in CSCs that are not observed in fibroblasts may provide valuable new CSC-specific markers. Methods: Alternative splicing and gene expression microarray strategies were used to identify selected exons and differentially expressed genes between 10 Basal human breast cancer cell lines and a combination of 12 Luminal and 3 fibroblast cell lines. Q-PCR analysis was conducted to determine candidate CSC gene differential expression between Basal, Luminal, and Fibroblast cells lines. Results: Expression levels of 11 genes were higher and 24 genes were lower in the Basal cell lines versus Luminal or fibroblastic cell lines. Comparison of Basal cell lines to the Luminal/Fibroblast cell lines identified 36 cassette exons that were included, and 26 that were excluded in Basal cell lines. Also, 19 genes were upregulated in Basal cell lines compared to the other groups as detected by Q-PCR. Interestingly, the 19-multigene model defined the Triple Negative Breast Cancer patients that were Likely to Recur under standard chemotherapy with a p = 1.90e-03 and AUC 0.723. Conclusions: Gene and exon marker sets distinguish CSC versus fibroblasts and may be instructive in identifying patients that recur early in Triple Negative Breast Cancer. The CSC-associated RNA signatures identified here will be further refined to develop new CSC-specific diagnostic markers to stratify breast cancer patients and monitor response to novel CSC-targeted therapies.

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Extinction of gene expression in somatic cell hybrids — a reflection of important regulatory mechanisms?

Trends in Genetics ◽

10.1016/0168-9525(93)90088-y ◽

1993 ◽

Vol 9 (7) ◽

pp. 240-245 ◽

Cited By ~ 29

Author(s):

Michael Boshart ◽

Doris Nitsch ◽

Günther Schütz

Keyword(s):

Gene Expression ◽

Somatic Cell ◽

Regulatory Mechanisms ◽

Somatic Cell Hybrids ◽

Cell Hybrids

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The expression of several T cell-specific and novel genes is repressed by trans-acting factors in immature T lymphoma clones.

Journal of Experimental Medicine ◽

10.1084/jem.174.1.269 ◽

1991 ◽

Vol 174 (1) ◽

pp. 269-280 ◽

Cited By ~ 7

Author(s):

M F Wilkinson ◽

J Doskow ◽

R von Borstel ◽

A M Fong ◽

C L MacLeod

Keyword(s):

T Cell ◽

Somatic Cell ◽

Cell Lines ◽

Hybrid Cells ◽

Somatic Cell Hybrids ◽

Novel Genes ◽

Mrna Accumulation ◽

Cell Hybrids ◽

T Lymphoma ◽

Cell Ontogeny

Cell surface proteins encoded by members of the immunoglobulin supergene family are sequentially expressed during T cell ontogeny. The molecular mechanisms responsible for the regulation of these surface molecules are not well understood. To investigate this issue, we used a series of well characterized T lymphoma cell clones with phenotypes characteristic of distinct stages of early thymocyte maturation. Somatic cell hybrids formed from these cell lines were employed to detect the presence of negative regulatory molecules. The expression of CD4 and CD8 was strongly repressed in hybrids formed between a CD4+ CD8+ lymphoma clone and "immature" CD4- CD8- lymphoma clones. Individual subunits of the T cell receptor (TCR)/CD3 complex displayed independent regulation in unique patterns in hybrid cells. Hybrids formed by fusing CD3+ and CD3- cells completely repressed CD3-delta mRNA expression while CD3-gamma, -epsilon, and -zeta transcripts were moderately inhibited or codominantly regulated. Similar to CD3-delta, interleukin 2R-alpha(IL-2R-alpha), and TCR-beta mRNA accumulation was trans-negatively regulated. Transcription rate measurements demonstrated that the inhibition of CD4, CD8, CD3-gamma, CD3-epsilon, TCR-beta, and IL-2R-alpha mRNA accumulation in hybrid cells was exerted, at least in part, at the transcriptional level. To test whether repressional regulation is a general feature of T cells, we examined the regulation of six novel genes which were selected solely on the basis of their differential expression between two of the cell lines used in this study. Five of the six novel gene transcripts were repressed in the somatic cell hybrids. Thus, inhibitor factors appear to play a general role in controlling T cell gene expression. The model system presented here may be useful for the identification and characterization of repressor molecules responsible for the regulation of genes expressed during T cell ontogeny.

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