Cross contamination meets misclassification: Awakening of CHP‐100 from sleeping beauty sleep—A reviewed model for Ewing's sarcoma

Abstract

A human cell line of neuroblastic tissue, which was believed to have been lost to science due to its unavailability in public repositories, is revived and reclassified. In the 1970s, a triple set of neuroblastoma (NB) cell lines became available for research as MYCN‐amplified vs nonamplified models (CHP‐126/‐134 and CHP‐100, respectively). Confusingly, CHP‐100 was used in subsequent years as a model for NB and, since the 1990s, as a model for neuroepithelioma and later as a model for Ewing's sarcoma (ES), which inevitably led to non‐reproducible results. A deposit at a bioresource center revealed that globally available stocks of CHP‐100 were identical to the prominent NB cell line IMR‐32 and CHP‐100 was included into the list of misidentified cell lines. Now we report on the rediscovery of an authentic CHP‐100 cell line and provide evidence of incorrect classification during establishment. We show that CHP‐100 cells carry a t(11;22)(q24;q12) type II EWSR1‐FLI1 fusion and identify it as a classic ES. Although the question of whether CHP‐100 was a virtual and never existing cell line from the beginning is now clarified, the results of all relevant publications should be considered questionable. Neither the time of the cross‐contamination event with IMR‐32 is known nor was the final classification as a model for Ewing family of tumors available with an associated short tandem repeat profile. After a long road of errors and confusion, authentic CHP‐100 is now characterized as a type II EWSR1‐FLI1 fusion model 44 years after its establishment.

Complete Purging of Ewing Sarcoma Metastases from Human Ovarian Cortex Tissue Fragments by Inhibiting the mTORC1 Signaling Pathway

“…Patient-derived Ewing’s sarcoma cell lines ES2, ES7 [ 37 ], CHP-100 [ 38 ] and EW8 [ 39 ], all express functional transcripts from the EWS-FLI1 fusion gene and have been widely used for Ewing’s sarcoma related research. Cell lines were cultured in Dulbecco’s Modified Eagle’s medium (DMEM, BioWhittaker, Basel, Switzerland) supplemented with 10% Fetal Bovine Serum (FBS, Gibco, Life Technologies, Carlsbad, CA, USA) and 40 µg/mL gentamicin (Centrafarm, Breda, The Netherlands).…”

THP‐1 reference data: Proposal of an in vitro branched evolution model for cancer cell lines

“…G-banding analysis of RCB1189 shows several derivative chromosomes and karyotype differences between cells (Figure S2), indicating that it consists of a heterogeneous cell population. The karyotype of RCB1189 can be described as follows: 86$92,XXYY,-X [8],-Y [6],+1 [8],+1 [4],add(1)(p13) [8],add(1) [3],add(1) (q21) [8],add(1)(q21) [2],del(1)(p?) [2],+2 [4],add(2)(p11) [2],i(2)(p10) [2], i(2)(q10) [7],+3 [6],-5 [3],+6 [10],+6 [8],del(6)(p21)x3 [10],del (6) [8],i(7) (p10) [2],-8 [10],-9 [9],-11 [10],add(11)(q23)x2 [10],add(12)(q24) [8],+13 [4],add(13)(p11) [10],add (13) [3],-17 [3],del(17)(p11)x2 [2],i(17)(q10) [6],+18 [2],-18 [3],-19 [8],-19 [7],add(20)(p11) [10],add (20) [5],add (20) (p11) [3],-21 [10],-22 [6],+mar1x2 [10],+mar2…”

“…These four THP‐1 cell lines have been registered under the same name and are listed in Cellosaurus with a single accession number (Table 1). Although identity of the cellular origin can be confirmed by STR analysis, which excludes misidentified cell lines, 6 the presence or absence of any genomic differences has not been elucidated. MCF7 and HeLa sublines indicate that genomic evolution of cancer cell lines results in a high degree of variation between laboratories, which must be taken into account in experimental reproducibility and data interpretation 7,8 …”