TET2 controls chemoresistant slow-cycling cancer cell survival and tumor recurrence
Isabel Puig, … , Josep Tabernero, Héctor G. Palmer
Isabel Puig, … , Josep Tabernero, Héctor G. Palmer
Published June 26, 2018
Citation Information: J Clin Invest. 2018;128(9):3887-3905. https://doi.org/10.1172/JCI96393.
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TET2 controls chemoresistant slow-cycling cancer cell survival and tumor recurrence

Abstract

Dormant or slow-cycling tumor cells can form a residual chemoresistant reservoir responsible for relapse in patients, years after curative surgery and adjuvant therapy. We have adapted the pulse-chase expression of H2BeGFP for labeling and isolating slow-cycling cancer cells (SCCCs). SCCCs showed cancer initiation potential and enhanced chemoresistance. Cells at this slow-cycling status presented a distinctive nongenetic and cell-autonomous gene expression profile shared across different tumor types. We identified TET2 epigenetic enzyme as a key factor controlling SCCC numbers, survival, and tumor recurrence. 5-Hydroxymethylcytosine (5hmC), generated by TET2 enzymatic activity, labeled the SCCC genome in carcinomas and was a predictive biomarker of relapse and survival in cancer patients. We have shown the enhanced chemoresistance of SCCCs and revealed 5hmC as a biomarker for their clinical identification and TET2 as a potential drug target for SCCC elimination that could extend patients’ survival.

Authors

Isabel Puig, Stephan P. Tenbaum, Irene Chicote, Oriol Arqués, Jordi Martínez-Quintanilla, Estefania Cuesta-Borrás, Lorena Ramírez, Pilar Gonzalo, Atenea Soto, Susana Aguilar, Cristina Eguizabal, Ginevra Caratù, Aleix Prat, Guillem Argilés, Stefania Landolfi, Oriol Casanovas, Violeta Serra, Alberto Villanueva, Alicia G. Arroyo, Luigi Terracciano, Paolo Nuciforo, Joan Seoane, Juan A. Recio, Ana Vivancos, Rodrigo Dienstmann, Josep Tabernero, Héctor G. Palmer

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Figure 8

TET2 determines tumor recurrence.

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TET2 determines tumor recurrence. (A and B) SCCC proportion (n = 4 xenog...
(A and B) SCCC proportion (n = 4 xenografts per condition) (A) and apoptosis (n = 6–16 xenografts per condition) (B) were evaluated by flow cytometry (A) and caspase-3 (CASP3) immunostaining (B) in the indicated cell lines growing as xenografts in mice treated or not treated with oxaliplatin (OX). Percentage of SCCC measurements: shCTRL OX vs. shTET2 VEH (P ≤ 0.0001)/shTET2 OX (P ≤ 0.001). 1-way ANOVA. (C) MT formation capacity was evaluated for RCCCs and SCCCs isolated from the indicated cell lines. Dots indicate the percentage of MTs grown in each single well. Data are represented as mean ± SEM of triplicates from 3 independent experiments. 2-tailed Student’s t test. (D and E) Evaluation of tumor regrowth after chemotherapy treatment. (D) NOD/SCID mice with established subcutaneous TET2-WT and TET2-KO xenografts were treated with OX. The animals received a total of 3 doses and were maintained for post-treatment observation. Each point represents the mean ± SEM of 20 xenografts. (E) The survival curve represents progression-free survival (PFS) percentages showing the impact of OX on the regrowth of TET2-WT or -KO xenografts. A 20% increase in tumor volume after treatment release was considered as regrowth or progression. Significance was calculated using the log-rank (Mantel-Cox) test. HR, hazard ratio; log-rank P value. (F) Representative pictures of SCCC apoptosis evaluated by CASP3 immunostaining in indicated xenografts. (B and F) Scale bars: 100 μm; high-magnification scale bars: 20 μm. Hoechst was used as nuclei counterstain. White arrowheads, SCCCs. (A and C) *P ≤ 0.05; **P ≤ 0.01; ****P ≤ 0.0001.