Reduced tumorigenesis in mouse mammary cancer cells following inhibition of Pea3- or Erm-dependent transcription

Abstract

Pea3 and Erm are transcription factors expressed in normal developing branching organs such as the mammary gland. Deregulation of their expression is generally associated with tumorigenesis and particularly breast cancer. By using RNA interference (RNAi) to downregulate the expression of Pea3 and/or Erm in a mammary cancer cell line, we present evidence for a role of these factors in proliferation, migration and invasion capacity of cancer cells. We have used different small interfering RNAs (siRNAs) targeting pea3 and erm transcripts in transiently or stably transfected cells, and assessed the physiological behavior of these cells in in vitro assays. We also identified an in vivo alteration of tumor progression after injection of cells that overexpress pea3 and/or erm short hairpin RNAs (shRNAs) in immunodeficient mice. Using transcriptome profiling in Pea3- or Erm-targeted cells, two largely independent gene expression programs were identified on the basis of their shared phenotypic modifications. A statistically highly significant part of both sets of target genes had previously been already associated with the cellular signaling pathways of the `proliferation, migration, invasion' class. These data provide the first evidence, by using endogenous knockdown, for pivotal and complementary roles of Pea3 and Erm transcription factors in events crucial to mammary tumorigenesis, and identify sets of downstream target genes whose expression during tumorigenesis is regulated by these transcription factors.

The Role of Pea3 Group Transcription Factors in Esophageal Squamous Cell Carcinoma

“…59,60 The importance of Pea3 group transcription factors in tumorigenesis is further strengthened by a recent study demonstrating that Pea3 and Erm are required for the tumorigenesis of mammary cancer cells. In that study, 30 the regulatomes of the two transcription factors were different, suggesting that Pea3 and Erm regulate distinct, but complementary, molecular networks. In the present study, we found that both Erm and Pea3 were overexpressed in human ESCC compared with their nontumor epithelia.…”

“…21 Erm knockdown reduces the tumorigenicity of mouse mammary cancer cells, and a high Erm expression level also acts as an independent adverse prognostic factor in patients with breast cancer. 30,31 Moreover, Erm overexpression enhances the aggressiveness of cancer cells in vitro and correlates with disease progression in endometrial carcinoma. [32][33][34] To the best of our knowledge, the roles of Pea3 group transcription factors in ESCC have not been studied.…”

Loss of a Negative Feedback Loop Involving Pea3 and Cyclin D2 Is Required for Pea3-Induced Migration in Transformed Mammary Epithelial Cells

“…TAC and MMT cells were obtained and cultured as described (16,22,30). Briefly, cells were maintained in DMEM supplemented with 10% FBS (Life Technologies).…”

“…A total of 3 Â 10 6 HEK 293 GP cells were transfected with pLPCX, pLPCX-Pea3-V5, pMX, or pMX-CylinD2 and 1.2 Â 10 6 MMT cells or 1 Â 10 6 TAC cells per 100-mm dish were incubated with supernatant as previously described (22). The selection procedure started the next day using 1 mg/mL (TAC) or 2 mg/mL (MMT) of Puromycin (Life Technologies).…”

“…Ultimately, the identification and characterization of new PEA3 target genes in the context of mammary tumorigenesis will shed light on new molecular mechanisms involved in this pathology. We previously identified, by DNA array, several new potential Pea3 target genes in the Pea3-dependent mammary tumorigenic cells (MMT) mammary tumorigenic line (22). Nonetheless, whether these genes are direct Pea3 targets and if they actively take part into the tumorigenic potential of Pea3 remains an open question.…”