ABSTRACT
Glioblastoma (GBM) is an aggressive and incurable tumor of the brain with limited treatment options. Current first-line standard of care is the DNA alkylating agent temozolomide (TMZ), but this treatment strategy adds only ~4 months to median survival due to the rapid development of resistance. While some mechanisms of TMZ resistance have been identified, they are not fully understood. There are few effective strategies to manage therapy resistant GBM, and we lack diverse preclinical models of acquired TMZ resistance in which to test therapeutic strategies on TMZ resistant GBM. In this study, we create and characterize two new GBM cell lines resistant to TMZ in vitro, based on the 8MGBA and 42MGBA cell lines. Analysis of the TMZ resistant (TMZres) variants in conjunction with their parental, sensitive cell lines shows that acquisition of TMZ resistance is accompanied by broad phenotypic changes, including increased proliferation, migration, chromosomal aberrations, and secretion of cytosolic lipids. Importantly, each TMZ resistant model captures a different facet of the "go" (8MGBA-TMZres) or "grow" (42MGBA-TMZres) hypothesis of GBM behavior. These in vitro model systems will be important additions to the available tools for investigators seeking to define molecular mechanisms of acquired TMZ resistance.
Subject(s)
Actin Cytoskeleton/drug effects , Antineoplastic Agents, Alkylating/pharmacology , Cell Proliferation/drug effects , Drug Resistance, Neoplasm/drug effects , Gene Expression Regulation, Neoplastic , Temozolomide/pharmacology , Actin Cytoskeleton/metabolism , Actin Cytoskeleton/ultrastructure , Apoptosis/drug effects , Brain Neoplasms/drug therapy , Brain Neoplasms/genetics , Brain Neoplasms/metabolism , Brain Neoplasms/pathology , Carmustine/pharmacology , Cell Cycle/drug effects , Cell Cycle/genetics , Cell Line, Tumor , Cell Movement/drug effects , Cell Size , Chromosome Duplication , DNA Modification Methylases/genetics , DNA Modification Methylases/metabolism , DNA Repair Enzymes/genetics , DNA Repair Enzymes/metabolism , Drug Resistance, Neoplasm/genetics , Glioblastoma/drug therapy , Glioblastoma/genetics , Glioblastoma/metabolism , Glioblastoma/pathology , Humans , Metabolic Networks and Pathways/drug effects , Metabolic Networks and Pathways/genetics , Metabolome/drug effects , Models, Biological , Neoplasm Proteins/genetics , Neoplasm Proteins/metabolism , Tumor Suppressor Proteins/genetics , Tumor Suppressor Proteins/metabolismABSTRACT
Since Cas was first identified as a highly phosphorylated 130 kilodalton protein that associated with the v-Src and v-Crk-oncoproteins, considerable effort has been made to determine its function. Its predicted role as a scaffolding molecule based on its domain structure has been largely confirmed. Through its ability to undergo rapid changes in phosphorylation, subcellular localization and association with heterologous proteins, Cas may spatially and temporally regulate the function of its binding partners. Numerous proteins have been identified that bind to Cas in vitro and/or in vivo, but in only a few cases is there an understanding of how Cas may function in these protein complexes. To date, Cas-Crk and Cas-Src complexes have been most frequently implicated in Cas function, particularly in regards to processes involving regulation of the actin cytoskeleton and proliferation. These and other Cas protein complexes contribute to the critical role of Cas in cell adhesion, migration, proliferation and survival of normal cycling cells. However, under conditions in which these processes are deregulated, Cas appears to play a role in oncogenic transformation and perhaps metastasis. Therefore, in its capacity as an adapter protein, Cas serves as a point of convergence for many distinct signaling inputs, ultimately contributing to the generation of specific cellular responses.
