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Role of Janus kinases (JAKs) and Signal Transducers and Activators of Transcription (STATs) in mammary gland development as well as cancer initiation and progression
Cancer cell dormancy in novel mouse models for reversible pancreatic cancer

Since its discovery as "just another kinase" more than twenty years ago, the family of JAK tyrosine kinases and their respective Signal Transducers and Activators of Transcription (STATs) has been a center of attention in the areas of signal transduction, development, and cancer. The subsequent designation of JAKs as Janus kinases after the mythical two-faced Roman God of the doorways accurately portrays the analogous and sometimes contrasting molecular and biological characteristics of these tyrosine kinases. The two "faces" of JAKs are their structurally similar kinase and pseudo-kinase domains. As essential parts of various transmembrane receptor complexes, these tyrosine kinases function at cellular gateways and relay signals from growth factors to their respective intracellular targets. The multifaceted nature of JAKs becomes evident from their ability to activate specific STATs during distinct phases of normal mammary gland development. Studies in breast cancer cells and genetically engineered mouse models also show that JAK/STAT signaling possesses a "two-faced" role during breast cancer initiation and progression. With JAK inhibitors currently under development to treat myeloproliferative disorders, determining the essential functions of JAKs at particular stages of disease initiation and progression is of critical importance to predict the efficacy of these agents for targeted therapies against breast cancer.

Significant advances have been made in the identification of key molecular pathways that play pivotal roles in the initiation and progression of pancreatic ductal adenocarcinoma (PDAC). Among the common genetic and epigenetic changes, oncogenic mutations in Kras and upregulation of the c-Myc oncogene are frequent events in PDAC. Using genetically defined in vivo models, several studies have recently demonstrated that expression of mutant Kras and c-Myc is equally important for the initiation and maintenance of pancreatic cancer. The targeted downregulation of a single oncogene resulted in cancer cell death at primary and metastatic sites. These findings are very encouraging and provide a strong rationale for the development of targeted therapies against these oncogenic drivers. Despite what seemed to be a complete response to the ablation of the oncogene, a few dormant cancer cells remained present, and it was demonstrated that they are a cellular reservoir for a swift relapse of pancreatic cancer following oncogene reactivation. Our team has an interest to understand the basic principles of cancer dormancy and the applicability of the novel genetic models for reversible metastatic PDAC to elucidate the role of cancer stem cells as well as biologic and molecular mechanisms that mediate the survival of dormant tumor cells.

Suitable animal models generated by our team for this project: 


Jak2 conditional knockout mice (Wagner et al., 2004)


Ligand-controlled expression of hyperactive Stat5 in the mammary gland and in hematopietic cells (Creamer et al., 2010Sakamoto et al., 2012Lin et al., 2013a, and Schmidt et al., 2014).

Suitable animal models generated by our team for this project: 


Ligand-controlled expression of c-Myc in pancreatic progenitors (Lin et al., 2013b)


Further reading

Conditional knockout of a gene of interest (GOI) in the mammary gland


Ligand-controlled expression of oncogenes in the mammary gland

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