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 August 31, 2018; First published June 26, 2018
Citation Information: J Clin Invest. 2018;128(9):3887-3905. https://doi.org/10.1172/JCI96393.
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Research Article Oncology

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 7

TET2 is essential for SCCC numbers and survival.

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TET2 is essential for SCCC numbers and survival. (A) Expression of TET2...
(A) Expression of TET2 was evaluated by Western blot in the indicated cell lines. Transient transfection of TET2 in HEK293T cells was used as positive control. Tubulin was used as loading control. The lanes were run on the same gel but were noncontiguous. Arrowhead, TET2 protein. CTRL, control; CMV, cytomegalovirus promoter. (B–G) Analysis of SCCC and RCCC viability was evaluated in the indicated cell lines growing as MTs. (B and C) Analysis of apoptosis (B) and proportion of SCCCs (C) by flow cytometry. Data are represented as mean ± SEM of triplicates from 3 independent experiments. Blue bars, RCCCs; green bars, SCCCs. (D) Representative pictures of immunofluorescence analysis of caspase-3 (CASP3). White arrowheads, SCCCs. (E) Histological quantification of 5hmC content in RCCCs and SCCCs per picture of paraffin-embedded MTs generated from the indicated cell lines. r.u., relative units. (F) Representative pictures of double 5hmC and H2BeGFP immunostaining of paraffin-embedded TET2-WT MTs. Red arrowheads, SCCCs containing 5hmC; white arrowheads, RCCCs. (G) Representative pictures of immunofluorescence staining to detect CASP3, H2BeGFP, and 5hmC colocalization in consecutive histological sections from paraffin-embedded TET2-KO MTs. White arrowheads, apoptotic SCCCs without 5hmC content. (D, F, and G) Scale bars: 100 μm; high-magnification scale bar: 20 μm. Hoescht was used as counterstain. (B, C, and E) *P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001; ****P ≤ 0.0001, 2-tailed Student’s t test.