Cytoskeletal alterations are known to influence the metastatic success of circulating tumor cells (CTCs). However, studies of the tumor cell cytoskeleton are almost exclusively focused on cells attached to surfaces or extracellular matrix leaving a significant knowledge gap relevant to metastasis. Recent work from the PI's research group has demonstrated that the cytoskeleton of circulating tumor cells responds very differently from cells attached to extracellular matrix. Specifically, free-floating tumor cells produce unique tubulin-based microtentacles (McTNs) that promote the reattachment of CTCs to endothelial cell layers. Imaging in live animals has shown that CTCs reattach to blood vessel walls via a cytoskeletal mechanism that matches McTNs. New data from the PI's lab now demonstrate that McTNs are detectable in tumor cells within hours of their isolation from breast cancer patients during surgery. Moreover, patient tumor cell drug responses can be gauged within minutes. Since McTNs are supported by tubulin, the common breast cancer drug, Paclitaxel (Taxol), actually strengthens McTNs and speeds tumor cell reattachment. Developing cancer drugs aimed at inhibiting attached tumor cell motility by targeting the actin cytoskeleton also enhance McTNs. These results emphasize the importance of determining whether cancer drugs aimed at cell division or the motility of attached tumor cells could inadvertently increase metastasis. Sinc both surgery and neoadjuvant chemotherapy can strongly increase the levels of CTCs, it is important to understand which molecular targets will reduce the metastatic efficiency of CTCs and which may increase metastatic risk. Nearly 90% of human solid tumors arise as carcinomas from epithelial cells, whose large size and rigidity often lead to their fragmentation in narrow capillaries. This restraint on metastatic efficiency could impose a selective pressure for circulating carcinoma cells to develop mechanisms to reattach to blood vessel walls and escape fragmentation. Recent work in the PI's lab has identified that McTNs are increased when the actin cortex beneath the plasma membrane is disrupted via either genetic alterations or chemical treatments. This study will test the hypothesis that genetic or therapeutic dysregulation of the actin cortex induces tubulin McTNs that promote the metastatic reattachment of circulating tumor cells. Predictions of this hypothesis will be tested in the following specific ais: 1) Define the molecular mechanism by which PTEN loss promotes McTNs. 2) Identify the role of Src signaling in McTN extension and tumor metastasis. 3) Examine the role of targeting Rho/ROCK mediated actin contractility on McTN generation. The long-term goals of this project are to define the molecular mechanisms that govern actin disruption to promote McTNs in circulating tumor cells. Extending our understanding of McTN structure and molecular regulation as well as examining McTN incidence and function in tumor cells derived from human breast cancer patients will both identify novel therapeutic targets and reveal potential metastatic risks of current cancer drugs.

Public Health Relevance

This project focuses on how circulating tumor cells produce unique extensions of their surface, known as microtentacles that were discovered in the PI's lab. These microtentacles improve the ability of circulating tumor cells to reattach in distant tissues. Microtentacles can actually be increased by cancer drugs that are aimed at cell growth, so it will be important to better understand the cytoskeleton of circulating tumor cells so that metastasis is not accidentally increased by current chemotherapies.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
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Tumor Progression and Metastasis Study Section (TPM)
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Ault, Grace S
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University of Maryland Baltimore
Schools of Medicine
United States
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Pratt, Stephen J P; Hernández-Ochoa, Erick O; Lee, Rachel M et al. (2018) Real-time scratch assay reveals mechanisms of early calcium signaling in breast cancer cells in response to wounding. Oncotarget 9:25008-25024
Bailey, Patrick C; Lee, Rachel M; Vitolo, Michele I et al. (2018) Single-Cell Tracking of Breast Cancer Cells Enables Prediction of Sphere Formation from Early Cell Divisions. iScience 8:29-39
Kallergi, G; Aggouraki, D; Zacharopoulou, N et al. (2018) Evaluation of ?-tubulin, detyrosinated ?-tubulin, and vimentin in CTCs: identification of the interaction between CTCs and blood cells through cytoskeletal elements. Breast Cancer Res 20:67
Ory, Eleanor C; Chen, Desu; Chakrabarti, Kristi R et al. (2017) Extracting microtentacle dynamics of tumor cells in a non-adherent environment. Oncotarget 8:111567-111580
Ory, Eleanor C; Bhandary, Lekhana; Boggs, Amanda E et al. (2017) Analysis of microtubule growth dynamics arising from altered actin network structure and contractility in breast tumor cells. Phys Biol 14:026005
Chakrabarti, Kristi R; Andorko, James I; Whipple, Rebecca A et al. (2016) Lipid tethering of breast tumor cells enables real-time imaging of free-floating cell dynamics and drug response. Oncotarget 7:10486-97
Boggs, Amanda E; Vitolo, Michele I; Whipple, Rebecca A et al. (2015) ?-Tubulin acetylation elevated in metastatic and basal-like breast cancer cells promotes microtentacle formation, adhesion, and invasive migration. Cancer Res 75:203-15
Chakrabarti, Kristi R; Hessler, Lindsay; Bhandary, Lekhana et al. (2015) Molecular Pathways: New Signaling Considerations When Targeting Cytoskeletal Balance to Reduce Tumor Growth. Clin Cancer Res 21:5209-5214
Thompson, Keyata N; Whipple, Rebecca A; Yoon, Jennifer R et al. (2015) The combinatorial activation of the PI3K and Ras/MAPK pathways is sufficient for aggressive tumor formation, while individual pathway activation supports cell persistence. Oncotarget 6:35231-46
Chakrabarti, Kristi R; Whipple, Rebecca A; Boggs, Amanda E et al. (2015) Pharmacologic regulation of AMPK in breast cancer affects cytoskeletal properties involved with microtentacle formation and re-attachment. Oncotarget 6:36292-307

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