title: Inhibitors of Rho kinase (ROCK) signaling revert the malignant phenotype of breast cancer cells in 3D context.
abstract: Loss of polarity and quiescence along with increased cellular invasiveness are associated with breast tumor progression. ROCK plays a central role in actin-cytoskeletal rearrangement. We used physiologically relevant 3D cultures of nonmalignant and cancer cells in gels made of laminin-rich extracellular matrix, to investigate ROCK function. Whereas expression levels of ROCK1 and ROCK2 were elevated in cancer cells compared to nonmalignant cells, this was not observed in 2D cultures. Malignant cells showed increased phosphorylation of MLC, corresponding to disorganized F-actin. Inhibition of ROCK signaling restored polarity, decreased disorganization of F-actin, and led to reduction of proliferation. Inhibition of ROCK also decreased EGFR and Integrinβ1 levels, and consequently suppressed activation of Akt, MAPK and FAK as well as GLUT3 and LDHA levels. Again, ROCK inhibition did not inhibit these molecules in 2D. A triple negative breast cancer cell line, which lacks E-cadherin, had high levels of ROCK but was less sensitive to ROCK inhibitors. Exogenous overexpression of E-cadherin, however, rendered these cells strikingly sensitive to ROCK inhibition. Our results add to the growing literature that demonstrate the importance of context and tissue architecture in determining not only regulation of normal and malignant phenotypes but also drug response.
authors.affiliation: Life Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, Berkeley, CA, USA.|Present address: Oncology Research Laboratories, Kyowa Hakko Kirin Co., Ltd., Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Matsubara
authors.affiliation: Life Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, Berkeley, CA, USA.
authors.forename: Mina J
authors.initials: MJ
authors.lastname: Bissell
mesh_terms: D008841:Actin Cytoskeleton / Q000187:drug effects / Q000201:enzymology; D015703:Antigens, CD; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D015820:Cadherins / Q000235:genetics / Q000378:metabolism; D000072645:Cancer-Associated Fibroblasts / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D045744:Cell Line, Tumor; D016764:Cell Polarity / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects; D018920:Coculture Techniques; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm; D005260:Female; D006801:Humans; D058990:Molecular Targeted Therapy; D010641:Phenotype; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects*; D014162:Transfection; D064726:Triple Negative Breast Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000473:pathology; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
chemical_list: D015703:Antigens, CD; D000970:Antineoplastic Agents; C513384:CDH1 protein, human; D015820:Cadherins; D047428:Protein Kinase Inhibitors; C066737:RHOA protein, human; C515851:ROCK1 protein, human; C515852:ROCK2 protein, human; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein
keywords: ROCK; breast cancer; invasiveness; polarity; three-dimensional culture