The long term goal of the proposed studies is to understand the signal transduction mechanisms in cancer development and progression. The previous funding period focused on the role of focal adhesion kinase (FAK) and several other proteins in the regulation of cell migration and breast cancer development and metastasis. We have illustrated the mechanisms by which FAK-mediated Src phosphorylation of endophilin A2 inhibits endocytosis of MT1-MMP to stimulate cancer cell invasion. Using a conditional KO approach, we showed that mammary epithelial-specific deletion of FAK leads to severe lobulo-alveolar hypoplasia and secretory immaturity of the murine mammary gland. Furthermore, we demonstrated that inactivation of FAK in mammary epithelial cells suppresses mammary tumorigenesis and progression by affecting mammary cancer stem/progenitor cells using the well-characterized MMTV-PyMT mouse model of human breast cancer. We also created the defined fibronectin gradients using microfluidics approaches and analyzed the role of FAK and a number of other signaling molecules in the regulation of directional cell migration. Additional studies identified a novel interaction between N-WASP and hnRNPK and showed that hnRNPK may function as a negative regulator of N-WASP to inhibit filopodia formation and cell spreading. This grant also supported our work on the role of nuclear localized actin regulatory proteins N-WASP and Arp2/3 complex in the regulation of RNA polymerase II- dependent transcription. In preliminary studies, we made the unexpected finding that inactivation of FIP200, a putative breast tumor suppressor based on initial studies in cancer cell lines, inhibits (rather than promotes) mammary tumorigenesis and progression in the MMTV-PyMT mouse model of breast cancer in vivo. We further showed that both intrinsic proliferative defects of FIP200-null mammary tumor cells as well as increased infiltration of immune cells in the tumor microenvironment may contribute to the suppression of mammary tumorigenesis and progression in MMTV- PyMT mice with conditional KO of FIP200. Based on these preliminary studies, we propose to determine the mechanisms by which FIP200 and its associated signaling pathways regulate breast cancer development and progression using a combination of molecular, cellular, immunological and mouse genetic approaches. We will 1). analyze molecular mechanisms of FIP200 regulation of mammary tumor cell proliferation using primary culture of isolated tumor cells, 2). examine the role and mechanisms of elevated immune cell infiltration in the suppression of mammary tumor development upon FIP200 ablation, and 3). investigate the potential role of FIP200 in mammary tumor maintenance.
Breast cancer is the most common malignancy among US women and a major health threat due to its high incidents and death rate. Analysis of molecular and cellular mechanisms by which key signaling molecules and their associated pathways and cellular processes regulate breast cancer development and progression using mouse models in vivo will significantly advance our understanding of the basic mechanisms of breast cancer that may contribute to novel therapies for the devastating disease.
|Wei, Huijun; Wang, Chenran; Croce, Carlo M et al. (2014) p62/SQSTM1 synergizes with autophagy for tumor growth in vivo. Genes Dev 28:1204-16|
|Chen, Yongqiang; Wei, Huijun; Liu, Fei et al. (2014) Hyperactivation of mammalian target of rapamycin complex 1 (mTORC1) promotes breast cancer progression through enhancing glucose starvation-induced autophagy and Akt signaling. J Biol Chem 289:1164-73|
|Fan, Huaping; Zhao, Xiaofeng; Sun, Shaogang et al. (2013) Function of focal adhesion kinase scaffolding to mediate endophilin A2 phosphorylation promotes epithelial-mesenchymal transition and mammary cancer stem cell activities in vivo. J Biol Chem 288:3322-33|
|Luo, Ming; Zhao, Xiaofeng; Chen, Song et al. (2013) Distinct FAK activities determine progenitor and mammary stem cell characteristics. Cancer Res 73:5591-602|
|Chen, Song; Guan, Jun-Lin (2013) Tumor-promoting and -suppressive roles of autophagy in the same mouse model of BrafV600E-driven lung cancer. Cancer Discov 3:1225-7|
|Zhao, Xiaofeng; Guan, Jun-Lin (2011) Focal adhesion kinase and its signaling pathways in cell migration and angiogenesis. Adv Drug Deliv Rev 63:610-5|
|Bae, Heekyong; Guan, Jun-Lin (2011) Suppression of autophagy by FIP200 deletion impairs DNA damage repair and increases cell death upon treatments with anticancer agents. Mol Cancer Res 9:1232-41|
|Fan, Huaping; Guan, Jun-Lin (2011) Compensatory function of Pyk2 protein in the promotion of focal adhesion kinase (FAK)-null mammary cancer stem cell tumorigenicity and metastatic activity. J Biol Chem 286:18573-82|