Asymmetric cell division promotes therapeutic resistance in glioblastoma stem cells
Masahiro Hitomi, Anastasia P. Chumakova, Daniel J. Silver, Arnon M. Knudsen, W. Dean Pontius, Stephanie Murphy, Neha Anand, Bjarne W. Kristensen, Justin D. Lathia
Masahiro Hitomi, Anastasia P. Chumakova, Daniel J. Silver, Arnon M. Knudsen, W. Dean Pontius, Stephanie Murphy, Neha Anand, Bjarne W. Kristensen, Justin D. Lathia
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Research Article Cell biology Stem cells

Asymmetric cell division promotes therapeutic resistance in glioblastoma stem cells

Abstract

Asymmetric cell division (ACD) enables the maintenance of a stem cell population while simultaneously generating differentiated progeny. Cancer stem cells (CSCs) undergo multiple modes of cell division during tumor expansion and in response to therapy, yet the functional consequences of these division modes remain to be determined. Using a fluorescent reporter for cell surface receptor distribution during mitosis, we found that ACD generated a daughter cell with enhanced therapeutic resistance and increased coenrichment of EGFR and neurotrophin receptor (p75NTR) from a glioblastoma CSC. Stimulation of both receptors antagonized differentiation induction and promoted self-renewal capacity. p75NTR knockdown enhanced the therapeutic efficacy of EGFR inhibition, indicating that coinheritance of p75NTR and EGFR promotes resistance to EGFR inhibition through a redundant mechanism. These data demonstrate that ACD produces progeny with coenriched growth factor receptors, which contributes to the generation of a more therapeutically resistant CSC population.

Authors

Masahiro Hitomi, Anastasia P. Chumakova, Daniel J. Silver, Arnon M. Knudsen, W. Dean Pontius, Stephanie Murphy, Neha Anand, Bjarne W. Kristensen, Justin D. Lathia

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Figure 4

p75NTR signaling modifies response to EGFR inhibition.

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p75NTR signaling modifies response to EGFR inhibition. (A) Immunoblottin...
(A) Immunoblotting detected SOX2 expression and EGFR receptor activation in T4121-PM-GFP CSCs after a 3-day treatment with stem cell medium (NB), FBS containing differentiation-inducing medium (FBS), differentiation medium with EGF (FBS + EGF; 20 ng/mL), NB with the EGFR inhibitor erlotinib (Erlo; 3 μM), or a combination of erlotinib and NGF (Erlo + NGF; 100 ng/mL) to stimulate p75NTR. (B) Immunoblotting detected STAT3, AKT, and ERK activation in T4121-PM-GFP CSCs after a 3-day treatment with stem cell medium (NB), the EGFR inhibitor erlotinib (NB + Erlo; 3 μM), or a combination of erlotinib and NGF (NB + Erlo + NGF; 100 ng/mL), BDNF (NB + Erlo + BDNF; 100 ng/mL), or the p75NTR ligand LM11A-31 (NB + Erlo + LM; 100 nM) to stimulate the p75NTR. (C) Immunoblotting for EGFR receptor activation and SOX2 expression in nontargeting (NT) and knockdown (KD1 and KD2) T4121-PM-GFP CSCs. Cells were treated for 3 days with CSC medium (NB) alone, CSC medium with the addition of the EGFR inhibitor erlotinib (Erlo; 3 μM), or 3 μM erlotinib and the p75NTR ligand, 100 nM LM11A-31 (Erlo+LM). (D) Kaplan-Meier plots indicate the survival of the mice that were intracranially implanted with T4121-PM-GFP CSCs that were transduced with nontargeting (NT) shRNA or p75NTR knockdown (KD1) shRNA. The erlotinib treatment group received 75 mg/kg per day (blue and red lines). Animals in the vehicle group were treated with 0.05% methylcellulose solution (black lines). Median survival and P value as determined by log rank test comparing the vehicle and erlotinib groups are shown. (E) Schematic depiction of the proposed model of signaling that occurs in GBM CSCs upon EGFR and p75NTR cosegregation during ACD. The 2 receptors signal through similar signaling pathways that promote the stem cell phenotype. Upon inhibition of EGFR by erlotinib, ligand-activated p75NTR takes over the downstream stimulation to maintain the stem cell program.