Supplementary Figure 3. (A) Relative initial telomere length of 17 glioma cell lines and NHA. (B) Correlation of IC50s of THIO and initial telomere length in 17 glioma cell lines. (C) Baseline relative expression of hTERT in 17 glioma cell lines and NHA. (D) RNAseq data of hTERT expression in 11 glioma cell lines obtained from CCLE. (E) Correlation of IC50s of THIO and baseline expression of hTERT in 17 glioma cell lines. (F) Correlation of IC50s of THIO and baseline expression of hTERT in 11 glioma cell lines from CCLE. (G) The heatmap of the enrichment scores of 5 telomere/telomerase-related gene signatures for 65 glioma cell lines from CCLE. (H-I) Relative telomere length of M059K and DBTRG-05MG cells following THIO treatment at 2.5 µM for 5 days. (J-K) Telomerase activity of M059K and DBTRG-05MG cells following THIO treatment at 5 µM for 72 hours. (L) Baseline telomerase activity of 10 glioma cell lines, including 5 cell lines that more sensitive to THIO and 5 cell lines that more resistant to THIO. (M) Correlation of baseline telomerase activity and cell viability (%) following THIO treatment. (N) Quantification of western blot of γH2AX expression in 8 glioma cell lines treated with THIO for 72 hours.
ARTICLE ABSTRACT
To investigate the therapeutic role of a novel telomere-directed inhibitor, 6-thio-2′-deoxyguanosine (THIO) in gliomas both in vitro and in vivo.
A panel of human and mouse glioma cell lines was used to test therapeutic efficacy of THIO using cell viability assays, flow cytometric analyses, and immunofluorescence. Integrated analyses of RNA sequencing and reverse-phase protein array data revealed the potential antitumor mechanisms of THIO. Four patient-derived xenografts (PDX), two patient-derived organoids (PDO), and two xenografts of human glioma cell lines were used to further investigate the therapeutic efficacy of THIO.
THIO was effective in the majority of human and mouse glioma cell lines with no obvious toxicity against normal astrocytes. THIO as a monotherapy demonstrated efficacy in three glioma cell lines that had acquired resistance to temozolomide. In addition, THIO showed efficacy in four human glioma cell lines grown as neurospheres by inducing apoptotic cell death. Mechanistically, THIO induced telomeric DNA damage not only in glioma cell lines but also in PDX tumor specimens. Integrated computational analyses of transcriptomic and proteomic data indicated that THIO significantly inhibited cell invasion, stem cell, and proliferation pathways while triggering DNA damage and apoptosis. Importantly, THIO significantly decreased tumor proliferation in two PDO models and reduced the tumor size of a glioblastoma xenograft and a PDX model.
The current study established the therapeutic role of THIO in primary and recurrent gliomas and revealed the acute induction of telomeric DNA damage as a primary antitumor mechanism of THIO in gliomas.
