Additional file 5 of Reliable assessment of telomere maintenance mechanisms in neuroblastoma

Additional file 5: Figure S2. Dependency of C-circle assay on threshold and reference cell line. (A) Southern blot of C-circle assay of different cell lines (CHLA-90: ALT[+], SK-N-BE(2): TEL[+], SK-N-FI: ALT[+], LM-216-J: ALT[+]), normal human tissue and neuroblastoma samples with high telomerase activity (all ALT-negative). Left columns: sample without polymerase, right columns: samples with polymerase. (B) Neuroblastoma samples for which APB and C-circle assay was available (n=67). Different thresholds applied to the same samples reveal different results. (th1) C-circle signal intensity ≥5% relative to the signal of CHLA-90. (th2) C-circle signal intensity ≥20% relative to the signal of CHLA-90 and at least fourfold the area under the curve of polymerase-free dot-blot. Number of cases (n) classified as ALT-positive according to the respective threshold are indicated. (C) Representative image of southern blot of C-Circle assay of different cell lines and neuroblastoma samples. Left columns: sample without polymerase, right columns: samples with polymerase. ALT-positive cell line CHLA-90 and ALT-negative cell line SK-N-BE are depicted at the top, ALT status according to threshold th1 as indicated.