Role of Jak/Stat Signaling in Mammary Gland Development and the Initiation and Progression of Mammary Cancer
Advisor: Prof. Kay-Uwe Wagner Wayne State University 2018-2024
Overview
The project focuses on the critical role of Janus Kinase 1 (JAK1) in the progression of mammary cancer, particularly in the context of ERBB2-driven mammary tumors. JAK1 is a protein tyrosine kinase involved in the cytokine-mediated activation of the STAT signaling pathway, which is pivotal in various biological processes including cell growth, survival, and differentiation. This study utilizes genetically engineered mouse models, specifically mammary-specific JAK1 conditional knockout mice, to dissect the role of JAK1 in mammary gland biology and tumorigenesis. By employing a combination of molecular biology techniques, including gene knockout, RNA sequencing, and protein analysis, the research aims to elucidate the mechanistic pathways through which JAK1 influences cancer cell behavior and tumor progression.
The research methodology integrates both in vitro and in vivo approaches to provide a comprehensive analysis of JAK1 function. This includes the generation of JAK1-deficient mammary cancer cell lines and their orthotopic transplantation into mice to study the effects on tumor growth and metastatic spread. Additionally, the project employs advanced imaging techniques to monitor tumor progression and metastasis in live animals. The overarching goal of this research is to validate JAK1 as a potential therapeutic target in breast cancer, offering insights into its role in cancer biology and the possibility of developing targeted therapies that could inhibit JAK1-mediated signaling pathways in cancer cells.
Key Findings
Loss of JAK1 prevents metastasis in an ERBB2-induced mammary cancer model.
JAK1 is the pivotal kinase mediating oncogenic STAT activation in ERBB2-transformed cells.
JAK1 signaling has pleiotropic effects on pathways associated with cancer progression.
STAT3, FOS, and MAP3K8 are JAK1 targets that promote migration and tumorsphere formation.
References
2021
Scientific Reports
Dual recombinase action in the normal and neoplastic mammary gland epithelium
Patrick D Rädler, Kerry Vistisen, Aleata A Triplett, and 7 more authors
We developed a transgenic mouse line that expresses the codon-optimized Flp recombinase under the control of the MMTV promoter in luminal epithelial cells of the mammary gland. In this report, we demonstrate the versatile applicability of the new MMTV-Flp strain to manipulate genes in a temporally and spatially controlled manner in the normal mammary gland, in luminal-type mammary tumors that overexpress ERBB2, and in a new KRAS-associated mammary cancer model. Although the MMTV-Flp is expressed in a mosaic pattern in the luminal epithelium, the Flp-mediated activation of a mutant KrasG12D allele resulted in basal-like mammary tumors that progressively acquired mesenchymal features. Besides its applicability as a tool for gene activation and cell lineage tracing to validate the cellular origin of primary and metastatic tumor cells, we employed the MMTV-Flp transgene together with the tamoxifen-inducible Cre recombinase to demonstrate that the combinatorial action of both recombinases can be used to delete or to activate genes in established tumors. In a proof-of-principle experiment, we conditionally deleted the JAK1 tyrosine kinase in KRAS-transformed mammary cancer cells using the dual recombinase approach and found that lack of JAK1 was sufficient to block the constitutive activation of STAT3. The collective results from the various lines of investigation showed that it is, in principle, feasible to manipulate genes in a ligand-controlled manner in neoplastic mammary epithelial cells, even when cancer cells acquire a state of cellular plasticity that may no longer support the expression of the MMTV-Flp transgene.
2020
Scientific Reports
Efficient tissue-type specific expression of target genes in a tetracycline-controlled manner from the ubiquitously active Eef1a1 locus
Kazuhito Sakamoto, Patrick D Rädler, Barbara L Wehde, and 8 more authors
Using an efficient gene targeting approach, we developed a novel mouse line that expresses the tetracycline-controlled transactivator (tTA) from the constitutively active Eef1a1 locus in a Cre recombinase-inducible manner. The temporally and spatially controlled expression of the EF1-LSL-tTA knockin and activation of tTA-driven responder transgenes was tested using four transgenic lines that express Cre under tissue-specific promoters of the pancreas, mammary gland and other secretory tissues, as well as an interferon-inducible promoter. In all models, the endogenous Eef1a1 promoter facilitated a cell-type-specific activation of target genes at high levels without exogenous enhancer elements. The applicability of the EF1-LSL-tTA strain for biological experiments was tested in two studies related to mammary gland development and tumorigenesis. First, we validated the crucial role of active STAT5 as a survival factor for functionally differentiated epithelial cells by expressing a hyperactive STAT5 mutant in the mammary gland during postlactational remodeling. In a second experiment, we assessed the ability of the EF1-tTA to initiate tumor formation through upregulation of mutant KRAS. The collective results show that the EF1-LSL-tTA knockin line is a versatile genetic tool that can be applied to constitutively express transgenes in specific cell types to examine their biological functions at defined developmental stages.
2018
Janus Kinase 1 Plays a Critical Role in Mammary Cancer Progression
Barbara L Wehde, Patrick D Rädler, Hridaya Shrestha, and 3 more authors
Janus kinases (JAKs) and their downstream STAT proteins play key roles in cytokine signaling, tissue homeostasis, and cancer development. Using a breast cancer model that conditionally lacks Janus kinase 1, we show here that JAK1 is essential for IL-6-class inflammatory cytokine signaling and plays a critical role in metastatic cancer progression. JAK1 is indispensable for the oncogenic activation of STAT1, STAT3, and STAT6 in ERBB2-expressing cancer cells, suggesting that ERBB2 receptor tyrosine kinase complexes do not directly activate these STAT proteins in vivo. A genome-wide gene expression analysis revealed that JAK1 signaling has pleiotropic effects on several pathways associated with cancer progression. We established that FOS and MAP3K8 are targets of JAK1/STAT3 signaling, which promotes tumorsphere formation and cell migration. The results highlight the significance of JAK1 as a rational therapeutic target to block IL-6-class cytokines, which are master regulators of cancer-associated inflammation.
