Increasing evidence demonstrates that cancer cells from solid tumors are highly heterogeneous, but it has been challenging to identify and to isolate those extremely tumorigenic tumor-repopulating cells as surface marker methods have been proven to be unreliable and their effectiveness has been controversial. During the last funding cycle, we developed a novel mechanical method of selecting and growing a subpopulation of cancer cells from melanoma cells using a soft fibrin matrix and demonstrated that they are highly tumorigenic in wild-type syngeneic and even nonsyngeneic mice. In this competitive renewal, we propose to elucidate the underlying mechanisms of how forces regulate gene expression, which is crucial in elucidating force-induced differentiation of highly tumorigenic tumor-repopulating cells. Our preliminary results suggest that epigenetic changes of H3K9 methylation levels are a link between force and Sox2 expression in the tumor-repopulating cells. We further show that focal adhesion kinase (FAK) activity is high in self-renewing tumor-repopulating cells but low in invading tumor-repopulating cells in the soft 3D matrix, that FAK activity in the cytoplasm and H3K9 methylation in the nucleus is inversely associated, and that silencing FAK leads to H3K9 methylation and inhibition of self-renewal of tumor-repopulating cells. Importantly, a local force of physiologic magnitudes via integrins on the cell surface is shown to be able to unfold chromatin segments and induce gene expression, suggesting a direct force-propagating pathway for gene expression in a live cell. Built on these preliminary results, we propose 3 specific aims to elucidate mechanotransduction mechanisms in the living cell:
Aim 1 : To elucidate how a surface force regulates methylation of H3K9 and self-renewal gene expression in tumor- repopulating cells;
Aim 2 : To elucidate how FAK activity and H3K9 methylation are regulated in TRC growth;
Aim 3 : To determine how a surface force alters gene expression in the nucleus of a cell. Our preliminary results support the feasibility of all 3 aims. We will employ several bioengineering approaches to apply forces to the living cell, and combine FRET technology, 3D imaging, BAC (bacterial artificial chromosome) transgene techniques to visualize, to quantitate, and to map mechanotransduction processes in the cytoplasm and in the nucleus of the living cell. The long term goal is to understand how forces and mechanical microenvironment in the 3D matrix regulate expression of self-renewing genes and differentiation genes, fundamental in elucidating how highly tumorigenic tumor-repopulating cells sustain self-renewal in soft low-force microenvironment.
Increasing evidence demonstrates that cancer cells from solid tumors are highly heterogeneous, but it has been challenging to identify and to isolate those extremely tumorigenic tumor-repopulating cells as surface marker methods have been proven to be unreliable and their effectiveness has been controversial. This research project aims to understand how forces and mechanical microenvironment in the 3D matrix regulate expression of self-renewing genes and differentiation genes; fundamental in elucidating how highly tumorigenic tumor-repopulating cells sustain self-renewal in soft low-force microenvironment. The long-term goal is to develop novel strategies to inhibit these tumor-repopulating cells in patients.
|Zhang, Yuejin; Wei, Fuxiang; Poh, Yeh-Chuin et al. (2017) Interfacing 3D magnetic twisting cytometry with confocal fluorescence microscopy to image force responses in living cells. Nat Protoc 12:1437-1450|
|Wang, Ning (2017) Review of Cellular Mechanotransduction. J Phys D Appl Phys 50:|
|Tan, Youhua; Wood, Adam Richard; Jia, Qiong et al. (2017) Soft matrices downregulate FAK activity to promote growth of tumor-repopulating cells. Biochem Biophys Res Commun 483:456-462|
|Ma, Jingwei; Zhang, Yi; Tang, Ke et al. (2016) Reversing drug resistance of soft tumor-repopulating cells by tumor cell-derived chemotherapeutic microparticles. Cell Res 26:713-27|
|Jia, Q; Zhou, W; Yao, W et al. (2016) Downregulation of YAP-dependent Nupr1 promotes tumor-repopulating cell growth in soft matrices. Oncogenesis 5:e220|
|Muhamed, Ismaeel; Wu, Jun; Sehgal, Poonam et al. (2016) E-cadherin-mediated force transduction signals regulate global cell mechanics. J Cell Sci 129:1843-54|
|Tajik, Arash; Zhang, Yuejin; Wei, Fuxiang et al. (2016) Transcription upregulation via force-induced direct stretching of chromatin. Nat Mater 15:1287-1296|
|Chen, Junjian; Zhou, Wenwen; Jia, Qiong et al. (2016) Efficient extravasation of tumor-repopulating cells depends on cell deformability. Sci Rep 6:19304|
|Li, Yong; Luo, Shunqun; Ma, Ruihua et al. (2015) Upregulation of cytosolic phosphoenolpyruvate carboxykinase is a critical metabolic event in melanoma cells that repopulate tumors. Cancer Res 75:1191-6|
|Barry, Adrienne K; Wang, Ning; Leckband, Deborah E (2015) Local VE-cadherin mechanotransduction triggers long-ranged remodeling of endothelial monolayers. J Cell Sci 128:1341-51|
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