title: Extracellular Proton Concentrations Impacts LN229 Glioblastoma Tumor Cell FateviaDifferential Modulation of Surface Lipids.
abstract: BACKGROUND
  Glioblastoma multiforme (GBM) is a highly aggressive form of brain cancer with marginal survival rates. GBM extracellular acidosis can profoundly impact its cell fate heterogeneities and progression. However, the molecules and mechanisms that enable GBM tumor cells acid adaptation and consequent cell fate competencies are weakly understood. Since extracellular proton concentrations (pHe) directly intercept the tumor cell plasma membrane, surface lipids must play a crucial role in pHe-dependent tumor cell fate dynamics. Hence, a more detailed insight into the finely tuned pH-dependent modulation of surface lipids is required to generate strategies that can inhibit or surpass tumor cell acid adaptation, thereby forcing the eradication of heterogeneous oncogenic niches, without affecting the normal cells.
  
  
  RESULTS
  By using image-based single cell analysis and physicochemical techniques, we made a small-scale survey of the effects of pH ranges (physiological: pHe 7.4,low: 6.2, andvery low: 3.4) on LN229 glioblastoma cell line surface remodeling and analyzed the consequent cell fate heterogeneities with relevant molecular targets and behavioral assays. Through this basic study, we uncovered that the extracellular proton concentration (1) modulates surface cholesterol-driven cell fate dynamics and (2) induces 'differential clustering' of surface resident GM3 glycosphingolipid which together coordinates the proliferation, migration, survival, and death reprogrammingviadistinct effects on the tumor cell biomechanical homeostasis. A novel synergy of anti-GM3 antibody and cyclophilin A inhibitor was found to mimic the very low pHe-mediated GM3 supraclustered conformation that elevated the surface rigidity and mechano-remodeled the tumor cell into a differentiated phenotype which eventually succumbed to the anoikis type of cell death, thereby eradicating the tumorigenic niches.
  
  
  CONCLUSIONS
  This work presents an initial insight into the physicochemical capacities of extracellular protons in the generation of glioblastoma tumor cell heterogeneities and cell deathviathe crucial interplay of surface lipids and their conformational changes. Hence, monitoring of proton-cholesterol-GM3 correlationsin vivothrough diagnostic imaging andin vitroin clinical samples may assist better tumor staging and prognosis. The emerged insights have further led to the translation of a 'pH-dependent mechanisms of oncogenesis control' into the surface targeted anti-GBM therapeutics.
authors.affiliation: Disease Biology Program, Department of Neurobiology and Genetics, Rajiv Gandhi Centre for Biotechnology , Thiruvananthapuram , India.
authors.forename: Sebastian
authors.initials: S
authors.lastname: John
authors.affiliation: Distributed Information Sub-Centre, Rajiv Gandhi Centre for Biotechnology , Thiruvananthapuram , India.
authors.forename: K C
authors.initials: KC
authors.lastname: Sivakumar
authors.affiliation: Disease Biology Program, Department of Neurobiology and Genetics, Rajiv Gandhi Centre for Biotechnology , Thiruvananthapuram , India.
authors.forename: Rashmi
authors.initials: R
authors.lastname: Mishra
keywords: GM3; antitumor therapy; cholesterol; cyclophilin A; extracellular pH dynamics; glioblastoma; glycosphingolipid conformational heterogeneity; surface clustering